Johanna N Bradie
email: johannabradie@hotmail.com

Sarah A Bailey
email: sarah.bailey@dfo.mpo.gc.ca

Gerard Van Der Velde
email: g.vandervelde@science.ru.nl

Hugh J Macisaac
email: hughm@uwindsor.ca

Brine-induced mortality of non-indigenous invertebrates in residual ballast

Keywords: ballast water treatment, Great Lakes, non-indigenous species, sodium chloride brine, acute toxicity, zooplankton, salinity, introduced species

All transoceanic vessels entering the Great Lakes are required to manage ballast water and ballast tank residuals with ballast water exchange and tank flushing, respectively. While these management procedures effectively reduce the density and richness of biota in ballast waters and thereby reduce the risk of transferring nonindigenous species, some ships are unable to uniformly manage all tanks. Laboratory experiments were conducted to evaluate sodium chloride brine as an emergency treatment for ballast tanks with non-compliant residuals. Invertebrate communities collected from i) Detroit River, ii) exchanged ballast tanks arriving in the Great Lakes, and iii) North Sea ports, were exposed to a range of brine concentrations (15‰-115‰) until complete mortality was reached. Results indicate that a one-hour exposure to 115‰ brine is a broadly effective treatment (>99.9% mortality) regardless of treatment temperature, taxonomic group, or species' source habitat salinity. A median of 0.00% (range 0.00-5.33) of individuals are expected to survive treatment and the expected number of viable individuals released after treatment is within Canadian and proposed international discharge standards. Before implementation, validation with ship-scale trials is recommended.

Introduction

Ballast water is utilized to control the trim, stability and stresses on operational ships that lack cargo. Worldwide, shipping operations move 10 billion m 3 of ballast water and the biota contained therein annually [START_REF] Rigby | Novel ballast water heating technique offers cost-effective treatment to reduce the risk of global transport of harmful marine organisms[END_REF]. Ballast water transfer provides a potent mechanism for dispersal of aquatic biota to locations far more distant than natural mechanisms alone could effect [START_REF] Locke | Ballast water exchange as a means of controlling dispersal of freshwater organisms by ships[END_REF][START_REF] Minton | Reducing propagule supply and coastal invasions via ships: Effects of emerging strategies[END_REF] and contributes significantly to non-indigenous species (NIS) introductions to aquatic systems globally [START_REF] Carlton | Trans-oceanic and interoceanic dispersal of coastal marine organisms -the biology of ballast water[END_REF][START_REF] Macisaac | Modelling ships' ballast water as invasion threats to the Great Lakes[END_REF].

Ships entering the Laurentian Great Lakes are effectively required to replace ballast water with mid-ocean seawater by exchanging full tanks or flushing residuals. Ballast water exchange and flushing reduce the risk of spreading NIS, particularly between freshwater regions, through a combination of purging and osmotic stress (see [START_REF] Gray | Efficacy of open-ocean ballast water exchange as a means of preventing invertebrate invasions between freshwater ports[END_REF][START_REF] Santagata | Effect of osmotic shock as a management strategy to reduce transfers of non-indigenous species among ports by ships[END_REF]. However, at least 4% of ballast tanks in transoceanic vessels arriving to the Great Lakes in 2007 were non-compliant with ballast management regulations (120 tanks of 2867 inspected; M.G. Deneau, Fisheries and Oceans Canada, unpubl. results). Although ships with non-compliant ballast water have the choice to retain non-compliant ballast water on board for the duration of their Great Lakes' operations, or to return to sea to complete ballast exchange and/or tank flushing, a rapid and effective back-up treatment is highly desirable to minimize ship delays. As the majority of ships' ballast tanks contain only residual ballast water at entry to the Great Lakes, adequate treatment of tank residuals is a high priority.

The addition of sodium chloride (NaCl) brine, herein referred to as brine, has been proposed as a cost-effective, readily-available treatment for management of non-compliant residual ballast water [START_REF] Jenkins | Brine as a treatment solution for the control of aquatic nuisance species introductions into the great lakes by NOBOB vessels[END_REF]. A feasibility study indicated that brine could be easily applied to ballast tanks at port through the ship's sounding tube and that short-term exposure of ballast tanks to high salinity brine should not cause undue corrosion [START_REF] Jenkins | Brine as a treatment solution for the control of aquatic nuisance species introductions into the great lakes by NOBOB vessels[END_REF]. In practice, because most ships will load ballast water into tanks at their first port-of-call in the Great Lakes, brine treatment of residual ballast could only be applied for a short time interval in some cases. As a result, an examination of the acute toxicity of brine exposure to aquatic invertebrates that are, or may be, transported by ship's ballast water is warranted.

As seawater (≥30‰ salinity) used in current ballast management practices is effective in reducing the viability of fresh-and brackish-water taxa through osmotic stress, brine (>230‰) is expected to be at least as effective as current ballast management if the final salinity concentration is optimized for the duration of exposure.

Altering the salinity of the surrounding environment can induce changes in the activity rate, internal volume, volume regulation, internal osmotic concentration, internal ionic content, ionic regulation, respiration rate, and oxygen requirements of aquatic organisms [START_REF] Schlieper | Part II: Physiology of brackish water[END_REF][START_REF] Hart | A review of the salt sensitivity of the Australian freshwater biota[END_REF]. A large and rapid increase in salinity is expected to disrupt the aforementioned processes resulting in mortality of ballastdwelling invertebrates. Furthermore, brine, which is manufactured from rock salt, differs substantially in ionic composition from natural ocean water, having 250% more sodium, chloride, calcium and strontium and <20% of the potassium and magnesium found in natural ocean water [START_REF] Turekian | Oceans[END_REF][START_REF] Hovanec | A chemical analysis of select trace elements in synthetic sea salts and natural seawater[END_REF]J.N. Bradie, unpubl. results). A high concentration of salts in an "unnatural" balance should cause mortality in aquatic taxa, and in fact, studies have shown that acute tolerance to NaCl is usually lower than acute tolerance to natural or artificial seawater [START_REF] Kefford | Comparing test systems to measure the salinity tolerance of freshwater invertebrates[END_REF].

Here the acute toxicity of NaCl brine exposure to aquatic invertebrates is examined in vitro. Addition of brine at high concentrations, for short time periods (i.e., hours), is expected to be the most feasible treatment application under typical operational schedules [START_REF] Jenkins | Brine as a treatment solution for the control of aquatic nuisance species introductions into the great lakes by NOBOB vessels[END_REF]. As the regulatory standard for treatment using ballast water exchange is at least 95% volumetric exchange of ballast with a final salinity of 30‰, we aim to determine the brine concentration required to exterminate at least 95% of aquatic invertebrates contained in ballast water, given a short duration of exposure. While [START_REF] Santagata | Concentrated sodium chloride brine solutions as an additional treatment for preventing the introduction of nonindigenous species in the ballast tanks of ships declaring no ballast on board[END_REF] determined that a one hour exposure to 110‰ brine was sufficient to cause 95% mortality, they conducted species-specific trials with only 25 species. In order to understand the efficacy of brine treatment more comprehensively, trials are conducted with diverse invertebrate communities collected from marine, freshwater and brackish-water habitats. We examine the effect of brine concentration, exposure time, treatment temperature, habitat salinity, and taxonomic affiliation on treatment efficacy to ensure that results are sufficiently robust to be applicable to all incoming vessels to the Great Lakes.

Materials and methods

Collection of samples

Invertebrates were collected in the field using vertical plankton net tows (53µm) and rinsed from the plankton net cod end into 25L unfiltered site water for transport to the laboratory. Ambient salinity and temperature of site water were measured at the time of collection using a YSI 556 multi-parameter instrument (YSI Incorporated, Yellow Springs, OH, USA) or digital thermometer and digital refractometer. Ambient site salinities ranged from 0-39‰ and temperatures ranged from 5.0-24.2°C. An extra 25L of ambient site water was collected for each trial and filtered (GF/F Whatman filter, 0.7 µm pore size) to remove organisms and other organic matter for later dilution of brine to pre-determined test concentrations.

Collection sites were: i) exchanged ballast tanks of five ships arriving in the Great Lakes between July and November 2007; ii) the Detroit River, collected between August 2007 and May 2008; and iii) the North Sea ports of Rotterdam, Antwerp and Bremen, with collections made between July and August 2008. One additional sample collected from the Waal River, the main distributary in the Rhine delta, at Nijmegen, The Netherlands, is treated herein as a North Sea sample. North Sea taxa were of significant interest because there is high shipping traffic between this region and the Great Lakes [START_REF] Ricciardi | Recent mass invasion of the North American Great Lakes by Ponto-Caspian species[END_REF][START_REF] Colautti | Spatial and temporal analysis of shipping vectors to the Great Lakes[END_REF] and because similar climatic conditions make it probable that individuals from North Sea ports will tolerate the abiotic conditions of Great Lakes' ports [START_REF] Reid | Geological and evolutionary underpinnings for the success of Ponto-Caspian species invasions in the Baltic Sea and North American Great Lakes[END_REF]. In addition, tidal salinity fluctuations in North Sea ports result in invertebrate assemblages that are at least moderately tolerant of salinity changes [START_REF] Barnes | The brackish-water fauna of northwestern Europe: An identification guide to brackish-water habitats, ecology and macrofauna for field workers, naturalists and students[END_REF], so they should be a conservative indicator of brine treatment efficacy. Slight variations in methodology occurred during trials for each site, and are described below as ballast tank, Detroit River, and North Sea experiments, respectively.

NaCl brine exposure experiments

Since most aquatic invertebrates are essentially thermo-conformers, temperature changes directly alter their metabolic rate, thereby affecting their ability to osmoregulate in hyperosmotic salinities [START_REF] Kinne | The effects of temperature and salinity on marine and brackish water animals[END_REF][START_REF] Schlieper | Part II: Physiology of brackish water[END_REF]. Brine treatment efficacy was examined at exposure temperatures of 11°C and 22°C to investigate efficacy throughout the shipping season. These temperatures were chosen based on ballast tank temperatures measured during sample collection in August and December for vessels entering the Great Lakes. North Sea experiments were conducted only at 22°C since there was no significant difference attributed to temperature after analyzing results from ballast tank and Detroit River trials (see 3.3). Brine treatment concentrations were chosen based on preliminary trials and findings of a brine treatment feasibility study [START_REF] Jenkins | Brine as a treatment solution for the control of aquatic nuisance species introductions into the great lakes by NOBOB vessels[END_REF]. Ballast tank taxa were exposed to brine concentrations of 60‰, 77‰, and 115‰ as recommended by [START_REF] Jenkins | Brine as a treatment solution for the control of aquatic nuisance species introductions into the great lakes by NOBOB vessels[END_REF]. In preliminary trials, Detroit River invertebrates displayed high mortality after exposure to 60‰ brine, so Detroit River samples were subsequently tested at 15‰, 30‰, and 60‰.

In contrast, North Sea taxa were exposed to brine concentrations of 77‰ and 115‰, since high variability in efficacy was observed after one hour exposure to 60‰ brine during ballast tank trials (see 3.2). The number of trials for each brine concentration and temperature is summarized in Table 1. A total of 17 replicated experiments were conducted.

Samples collected from sites with water temperatures of 17.3 to 24.2°C were stored at room temperature (22±1°C) until trials began, whereas samples collected from cold water sites (5.0 to 15.0°C) were placed in an environmental chamber at 11°C. Experiments began no more than 24 hours after sample collection and invertebrates were not fed during this interval. Treatment brine concentrations were produced by diluting stock brine (300‰; Pollard Highway Products, Harrow, ON, Canada) with filtered site water; final concentrations were checked using an optical or digital refractometer. Experiments were initiated by filtering a randomly drawn subsample through a 40µm sieve and rinsing retained invertebrates into a counting tray with ~80mL of diluted brine at a pre-determined treatment concentration or filtered site water (control). The volume of filtrate was dependent on animal density, with a target of ≥50 individuals per replicate for ballast tank and Detroit River experiments and ≥100 individuals per replicate for North Sea experiments. The number of individuals and taxonomic composition of each replicate was subject to random variation. Four replicates were set up for each treatment and control, with the exception of ballast tank trials and the Detroit River trial at 22°C, for which five replicates were used.

Invertebrate survival was assessed hourly in each replicate by viewing individuals under a Leica dissecting microscope at 10-80x magnification. Invertebrates that did not exhibit any movement, even in reaction to stimulation with a dissection probe, were considered dead. When all individuals in all replicates of a treatment appeared dead, brine exposure was ended. Individuals were then transferred to filtered site water for one hour to allow possible recovery, and then reassessed. If living individuals were found after the recovery period, survival rates for earlier time periods were adjusted to correct for later, higher, survival rates. Due to time constraints, at each observation time point, control groups were counted to determine the number of dead individuals in each tray whereas treatment groups were counted to determine the number of live individuals in each tray; at the termination of each trial, samples were preserved in 95% ethanol and counted in entirety to enable the calculation of percent mortality. Exposure times varied between one hour and six days due to variation in brine tolerance of taxa. Water samples from each replicate were tested to ensure that treatment concentration and temperature were maintained until the experiment was ended. Taxonomic identification was conducted for all individuals from ballast water experiments. Additionally, fixedcount sampling techniques were employed to subsample 100 individuals from each North Sea and Detroit River trial to identify to genus level [START_REF] Barbour | Subsampling of benthic samples: A defense of the fixed-count method[END_REF]. For North Sea trials, individuals surviving brine treatment were preserved separately, allowing for identification of resistant taxa. Invertebrates were identified using [START_REF] Koste | Rotatoria. Gebrüder Bortraeger[END_REF], [START_REF] Balcer | Zooplankton of the Great Lakes: A guide to the identification and ecology of the common crustacean species[END_REF], [START_REF] Barnes | The brackish-water fauna of northwestern Europe: An identification guide to brackish-water habitats, ecology and macrofauna for field workers, naturalists and students[END_REF], Hayward and Ryland (1995), [START_REF] Johnson | Zooplankton of the Atlantic and Gulf Coasts: A guide to their identification and ecology[END_REF], [START_REF] Bartsch | Halacaroidea Acari.: a guide to marine genera[END_REF], and [START_REF] Newell | Marine plankton[END_REF]; taxa from at least 37 genera were included in trials.

Data Analysis

Survival rates from brine exposure experiments were calculated as the proportion of individuals alive when brine exposure was ended. The number of dead individuals found in treatment groups may be attributed to individuals dead at the beginning of testing, individuals that died naturally during the test, or individuals that died as a result of brine exposure. To accurately report the mortality caused by brine treatment alone, it was necessary to exclude from analysis individuals that died from the former two sources.

Survival rate to brine treatment was calculated as: Survival rate (%) = TS / CS x 100% Equation 1where TS is the number of viable individuals / total number of individuals in the treatment (15‰, 30‰, 60‰, 77‰, 115‰) and CS is the number of viable individuals / total number of individuals in the control (filtered site water) at a given point in time [START_REF] Abbott | A method for computing the effectiveness of an insecticide[END_REF]. In cases where this equation yielded a survival rate greater than 100, this value was reduced to 100 for further analysis.

For statistical analysis, any replicate, or taxonomic group within a replicate, that had less than 10 individuals was excluded. Kruskal-Wallis tests were performed to determine if survival rates for different brine treatments or different treatment temperatures varied significantly [START_REF] Zar | Biostatistical Analysis[END_REF]. Kruskal-Wallis tests were also used to determine if there was a difference in survival to brine treatment based on an individual's life history (collection salinity, taxonomic affiliation). Wilcoxon rank sum tests were used to perform pair-wise comparisons of variables found to be significantly different using a Kruskal-Wallis test. A significance level of 95% was used for all analyses, except in cases where multiple tests were conducted on the same dataset, in which case a Bonferroni correction was applied. All tests, with the exception of one, compared experiments with an equal number of replicates; for the exception, one replicate was randomly excluded from analysis. It was not possible to test for a difference in survival due to temperature after exposure to 60‰ brine, because there were differences amongst experiments within treatments (see 3.4).

Results

Taxonomic Affiliation

Invertebrates tested were grouped as copepods, copepod nauplii, rotifers, and "other" taxa. Taxa in the "other" group included Cladocera (including, but not limited to, Bosmina spp., Leptodora spp., and Diaphanosoma spp.), Gastropoda and their larvae, Halacaridae, Insecta, Mysida, Nanorchestidae, Noctilucaceae, Polychaeta, and Protista.

Nauplii of Cirripedia were present in three trials at high abundance, and were considered a separate group in these trials. There was a significant difference in survival amongst taxonomic groups at 77‰ and 115‰ brine treatments (Fig. 1; Kruskal-Wallis, p<0.001), but not at the 60‰ concentration (p>0.05). For both 77‰ and 115‰ treatments, significantly more Cirripedia larvae survived than copepods, copepod nauplii, or rotifers (Wilcoxon rank sum test with Bonferroni correction, p<0.015), and survival of "other" species did not differ from that of other groups (Wilcoxon rank sum test with Bonferroni correction, p>0.04).

NaCl brine toxicity

Survival decreased with increasing brine concentration. The median survival rate for Detroit River invertebrates exposed to three hours of 15‰ brine treatment was 0.00% (range 0.00-29.82) (Fig. 2), whereas all Detroit River invertebrates died after one hour of exposure to 30‰ or 60‰ brine treatment (322 individuals) (Fig. 2a). For all invertebrates tested, the median survival rate after one hour of treatment with 60‰ brine, 77‰ brine, or 115‰ brine was 0.00%. However, there were important differences in the range of survival rates observed, which reflects variability in the consistency of treatment efficacy. One hour of 60‰ brine treatment resulted in survival rates between 0% and 100% (Fig. 2), whereas after two hours of exposure, survival rates were between 0.00% and 4.36% (Fig. 2). Survival rates between 0.00% and 12.09% were seen for 77‰ brine treatment, and survival rates between 0.00% and 5.33% were seen for 115% brine treatment. Survival rates for 60‰ are not directly comparable to results from 77‰ and 115‰ treatments, since they were not generated from the same experiments (see Table 1). A total of 126 of 13188 individuals tested (<0.01%) survived exposure to 77‰ brine, whereas only five of 13183 individuals tested (3.79%) survived exposure to 115‰ brine. Significantly greater mortality occurred with exposure to 115‰ than in 77‰ brine in four experiments (Fig. 3; Kruskal-Wallis, p<0.05). There was no significant difference in survival for ballast tank invertebrates exposed to 60‰ or 77‰ brine (Fig. 2c; Kruskal-Wallis, p>0.15).

Temperature

The effect of brine exposure was examined at 22°C and 11°C for all ballast tank and Detroit River trials. Although two copepod nauplii survived 115‰ brine treatment at 11°C and zero individuals survived the treatment at 22°C, the difference was not statistically significant. In fact, there was no significant difference in survival rates between the two temperatures for any of the treatment concentrations tested (Fig. 4; Kruskal-Wallis, p≥0.05).

Source Habitat Salinity

Taxa collected from freshwater habitats were much more susceptible to brine treatment than those from either brackish or marine habitats. No freshwater taxa survived one hour of 30‰ brine treatment (Fig. 2a), whereas some individuals of brackish and marine taxa survived treatment with 60‰, 77‰ and 115‰ brine (Figs. 2b,2c). Furthermore, survival after one hour of 77‰ brine treatment was significantly greater for individuals from 20 to 22‰ habitats than for those from 1 to 9‰ habitats (Fig. 3; Kruskal-Wallis, p<0.001; Wilcoxon rank sum test with Bonferroni correction, p<0.005). There was no difference in survival of taxa from different habitats after one hour of 115‰ brine treatment (Kruskal-Wallis, p>0.05).

Identification of

Discussion

This study indicates that treatment with 115‰ NaCl brine for one hour can be a rapid and effective strategy for emergency management of residual ballast water to prevent the introduction of nonindigenous invertebrate species to the Great Lakes.

While one hour treatment with 77‰ and 115‰ brine were both very effective (>99% mortality) against all taxa examined, 115‰ treatment was statistically more effective in several trials and yielded complete mortality more frequently, making this management option more preferable.

The effect of temperature on treatment efficacy was explored to ensure meaningful results irrespective of season, because the effects of salinity changes on aquatic taxa can be modulated by temperature [START_REF] Kinne | The effects of temperature and salinity on marine and brackish water animals[END_REF][START_REF] Browne | Combined effects of salinity and temperature on survival and reproduction of five species of Artemia[END_REF] and surface water temperature may vary between 0° and 27°C

when international ships are active on the Great Lakes [START_REF] Reid | Geological and evolutionary underpinnings for the success of Ponto-Caspian species invasions in the Baltic Sea and North American Great Lakes[END_REF]. At the brine concentrations examined here, survival was not significantly affected by temperature and thus brine treatment is expected to be effective throughout the shipping season. Since a species' salinity tolerance is influenced by the salinity of its natural habitat [START_REF] Costlow | Studies on the larval development of the crab, Rhithropanopeus harrisii Gould. I. The effect of salinity and temperature on larval development[END_REF][START_REF] Laughlin | Ontogeny of respiratory and growth responses of larval mud crabs Rhithropanopeus harrisii exposed to different temperatures, salinities and naphthalene concentrations[END_REF][START_REF] Fockedey | Temperature and salinity effects on post-marsupial growth of Neomysis integer Crustacea: Mysidacea[END_REF], our experiments included invertebrates collected from salinities between 0‰ and 34‰

to determine if all taxa arriving to the Great Lakes via ballast water would be susceptible to brine treatment. Mortality was not influenced by habitat salinity when taxa were treated with 115‰ brine, providing further evidence for the broad efficacy of this treatment. 77‰ brine treatment is not as broadly effective since taxa collected from 20 to 22‰ habitats survived this treatment significantly better than did those collected from 1 to 9‰ environments. However, these results show that taxa in ballast tanks that originate from habitats with low salinity -which would pose the greatest establishment threat to the Great Lakes -are the least likely to survive exposure to brine treatment.

The most resistant taxon to brine treatment was Cirripedia nauplii. Cirripedia nauplii are only infrequently observed and at very low density in residual ballast samples and therefore pose a relatively low risk for introduction to the Great Lakes [START_REF] Duggan | Invertebrates associated with residual ballast water and sediments of cargo-carrying ships entering the Great Lakes[END_REF]. Additionally, even if Cirripedia was introduced to the Great Lakes, it is a marine taxon that is not expected to survive in freshwater habitats. In fact, a comprehensive study on hull fouling found that Cirripedia were always dead or in poor condition when attached to ship hulls in the Great Lakes, presumably due to exposure to freshwater [START_REF] Sylvester | Is vessel hull fouling an invasion threat to the Great Lakes?[END_REF].

We estimate that treatment using 115‰ brine for one hour of exposure will be at least as effective as ballast water exchange, exterminating >99% of marine, brackish and freshwater organisms from residual ballast water. However, Canadian regulations require that any ballast water treatment other than ballast water exchange or tank flushing must reduce concentrations of viable organisms and indicator microbes below a specified discharge standard. For aquatic invertebrates with a minimum dimension greater than or equal to 50µm (i.e., the invertebrates examined in this study), the relevant discharge standard is less than 10 viable individuals m -3 (Government of Canada, 2006; see also USCG (2009) and IMO (2004) for proposed equivalent American and International standards). Given a median survival rate of 0.00% (range 0.00-5.33) and assuming a median density of 280 individuals m -3 in untreated residual ballast water [START_REF] Duggan | Invertebrates associated with residual ballast water and sediments of cargo-carrying ships entering the Great Lakes[END_REF], treatment with 115‰ brine for one hour is expected to result in a median density of 0 (range 0-15) individuals m -3 . Therefore, our recommended treatment application is expected to achieve results that are largely compliant with the relevant discharge standard. Furthermore, taxa arriving in ballast water are likely in poor condition from transit, and may be more susceptible to unfavourable conditions than would the healthy port taxa tested here [START_REF] Wonham | Going to the source: role of the invasion pathway in determining potential invaders[END_REF].

While brine treatment at our recommended dosage appears highly effective, we acknowledge two limitations to our study. First, although ballast water may contain many different taxa, mainly zooplankton were tested in these experiments. Zooplankton were used as model organisms because they are abundant in ballast tanks, because their viability can be assessed easily using light microscopy, and because the Great

Lakes have sustained many invasions by this group (e.g. Bythotrephes longimanus, Cercopagis pengoi, Daphnia lumholtzi). However, discharge standards for ballast water regulate all aquatic taxa greater than 10 µm in minimum dimension, as well as indicator microbes. Thus, it is necessary to consider a broader range of taxa when assessing brine treatment as results from zooplankton alone may not reflect efficacy against all biotic groups. It is known that NaCl concentrations >10‰ will eliminate most bacteria and NaCl concentrations >30‰ will be toxic to many fungi (Dr. Carol Litchfield, George

Mason University, personal communication). Additionally, preliminary tests have shown that the round goby (Neogobius melanostomus), a previously introduced fish known to be susceptible to ballast water exchange [START_REF] Ellis | Salinity tolerance of Great Lakes invaders[END_REF], is killed by brine exposure of 45‰ to 60‰ [START_REF] Santagata | Effect of osmotic shock as a management strategy to reduce transfers of non-indigenous species among ports by ships[END_REF]. Therefore, although it requires empirical examination, we expect that non-halophilic taxa that are transported in ballast water will be negatively affected by brine treatment.

Second, our recommendations are based on laboratory, rather than ship-scale, trials. Laboratory studies were used to establish a 'proof of principle' and because they allowed us to manipulate variables that would not have been feasible in shipboard studies. Our recommendation of 115‰ treatment for one hour assumes complete mixing in tanks to achieve a uniform salinity. However, ballast tank structure is complex, with multiple longitudinal and transverse members that could restrict uniform application of brine to ballast residuals; higher survival rates would be expected if brine application is spatially heterogeneous. Ship-scale studies are required to determine if brine treatment will be equally effective under operational conditions.

Before implementation of this treatment, the environmental impact of releasing brine into the Great Lakes must be considered. Concern exists about the environmental consequences of road salt run-off entering waterways (d'Itri, 1992;[START_REF] Jones | Environmental impact of road salting[END_REF][START_REF] Forman | Roads and their major ecological effects[END_REF] and because brine would be released into the Great Lakes post-treatment, it could contribute to the problem. Residual ballast typically amounts to less than 0.5% of tank capacity (~10 tonnes), so only small volumes of brine (~10 tonnes) would be required to conduct 115‰ treatment. As a result, the treated tank could (and should) be filled with Great Lakes water before discharge to dilute the brine to concentrations ≤10‰. The brine is expected to be further diluted by at least a factor of 10 with discharge, so the impact of brine treatment should be minimal and spatially localized.

Conclusions

One-hour treatment of 115‰ brine exterminated nearly all invertebrate ballast water taxa (>99.99%) in laboratory trials. Survival is not affected by temperature, species' habitat salinity, or by taxonomic affiliation. Post-treatment densities of viable invertebrates comply with relevant Canadian and proposed international discharge standards and should be at least as effective as current ballast water management practices of vessels entering the Great Lakes. Survival rates have been corrected to account for mortality in controls (see 2.3). (3 hours). Survival rates have been corrected to account for mortality in controls (see 2.3). The effect of temperature on survival rate was found to be statistically insignificant.

Figure 1 .

 1 Figure 1. Mean (+SD) survival rate for copepods (black bars), copepod nauplii

Figure 2 .

 2 Figure 2. Mean (+SD) survival rate for (A) freshwater, (B) North Sea, and (C)

Figure 3 .

 3 Figure 3. Mean (+SD) survival rate for organisms exposed to one hour of 77‰

Figure 4 .

 4 Figure 4. Mean (+SD) survival rate for (A) freshwater, and (B) ballast water

  Survivors 98 individuals in North Sea trials and 17 individuals in ballast tank trials survived one hour of 77‰ brine treatment. These survivors were 93 Cirripedia nauplii, four copepod nauplii, one Nanorchestes sp., one Rhombognathides sp., one Nereis sp., and 15 unidentified individuals. The median survival rate for Cirripedia nauplii was 2.06% (range 0.00-12.21) for this treatment. Five individuals, including two Cirripedia nauplii, two copepod nauplii, and one Nanorchestes sp., survived one hour of 115‰ brine treatment. The median survival rate for Cirripedia nauplii was 0.00% (range 0.00-0.09) in this treatment.

Table 1 .

 1 Number of trials conducted for each temperature x brine concentration combination, by sample source location. Sample source locations: T-ballast tank that has undergone ballast water exchange; D-Detroit River; A= Port of Antwerp; R-Port of Rotterdam; B=Port of Bremen; N-Waal River, Nijmegen.

				11°C					22°C
	Sample	15	30	60	77	115	15	30	60	77	115
	Source
	T			3	3	3			2	2	2
	D	1	1	1			1	1	1
	A									3	3
	R									5	5
	B									1	1
	N									1	1

Acknowledgements

This project was funded by Transport Canada, Fisheries and Oceans Canada, and the NSERC Canadian Aquatic Invasive Species Network (CAISN). We thank M. Deneau, C. Simpkins, F. Sylvester, M. Whitehead, C. van Overdijk, S. Ellis, and O. Raza for assistance in the field and laboratory. We also thank M. Orbons and M. Versteeg for help with North Sea sampling and trials. H. Proctor and I. Bartsch provided assistance with taxonomic identifications, and J.C. Barrette and B. Middleton assisted with metals analysis.


James Matthew

Lloyd Williamson

Charlotte I Skinner

David B Hocken

Jml Williamson
email: jmlw@doctors.org.uk

come

Introduction

The media may affect how illness is perceived, in terms of its prevalence, severity and outcomes. The media also influences our perception of death and leads to an over-estimation of incidence of some causes of mortality. Articles depicting medical subjects may not be in-depth and are often influenced by non-medical issues. The media has both a positive impact on the population, in providing opportunistic health information, and a negative impact, causing an over-estimation of severity and incidence of certain diseases. This article aims to assess if media reporting of illness and death represents national statistics.

Method

The 10 most common daily read UK newspapers were assessed for articles relating to the most common causes of UK mortality. The searches were performed via each newspaper's online search facility over a 12-month period. Where appropriate, media friendly terms were used as search terms.

Results

18,482 pertinent articles were found relating to the most common causes of death in the UK. When the reportage of illness was compared to the actual incidence Cerebrovascular accidents and Chronic obstructive pulmonary disease were underrepresented in the media, with ratios 0.31 and 0.01 to 1 respectively. Flu/pneumonia, prostate cancer, dementia and breast cancer all have a large media profile, with ratios of 5.52, 3.06, 4.09 and 4.9 to 1 respectively.

Conclusion

The media has a significant impact on our perceptions of illness and death. This may influence how patients seek medical attention and their concerns at consultation. Strategies to improve the educational content of the media may enhance the dissemination of health information via this resource.

What's already known about this topic?

The media is known to greatly impact on the public's understanding and perception of death and illness. Estimations of causes of death by the public often bear little relation to official statistics, but do correlate with the frequency of print media reporting. Previous research has shown that certain cancers are under-or overrepresented in the press and on the internet, but little is known about the representation of common causes of mortality.

What does this article add?

This article highlights the discrepancy between actual incidence and media coverage of certain causes of death. Over-represented diseases may be considered to be more serious and pose more of a threat than equally serious under-represented infectious diseases. This disproportionate media exposure may affect patients' concerns when seeking consultation.

Introduction

The media is considered to be the most important source of health information for the general public [START_REF] Plos | False hopes, unwarranted fears: The trouble with medical news stories[END_REF][START_REF] Williamson | How does the media profile of cancer compare with prevalence?[END_REF]. The media decides on what issues to present to the population and the level of importance attached to them, influencing public understanding and awareness of disease [START_REF] Schwitzer | What are the roles and responsibilites of the media in disseminating health information[END_REF]. Therefore, the media may affect how illness is perceived, in terms of its prevalence, severity and outcomes [START_REF] Plos | False hopes, unwarranted fears: The trouble with medical news stories[END_REF][START_REF] Williamson | How does the media profile of cancer compare with prevalence?[END_REF][START_REF] Mazur | Sounding the global alarm: Environmental issues in the US National News[END_REF][START_REF] Holder | Media advocacy in community prevention: news as a means to advance policy change[END_REF][START_REF] Young | Medicine in the popular press: the influence of media on perceptions of disease[END_REF][START_REF] Frewer | The media and genetically modified foods: evidence in support of social amplification of risk[END_REF]. In terms of what is reported by the print media, articles tend to be on subjects that are prevalent, relevant and of interest to the public [START_REF] Holder | Media advocacy in community prevention: news as a means to advance policy change[END_REF]. Articles depicting medical subjects may not be in-depth and are often influenced by non-medical issues, such as celebrity status or significant public events [START_REF] Williamson | How does the media profile of cancer compare with prevalence?[END_REF][START_REF] Schwitzer | What are the roles and responsibilites of the media in disseminating health information[END_REF][START_REF] Holder | Media advocacy in community prevention: news as a means to advance policy change[END_REF][START_REF] Chapman | Impact of celebrity illness on breast cancer screening: Kylie Minogue's breast cancer diagnosis[END_REF][START_REF] Williamson | Pancreatic cancer in the media: the Swayze shift[END_REF]. Thus there may be a discrepancy in the reportage of illness compared to prevalence of actual disease [START_REF] Plos | False hopes, unwarranted fears: The trouble with medical news stories[END_REF][START_REF] Williamson | How does the media profile of cancer compare with prevalence?[END_REF]. The media also influences our perception of death and, in particular, leads to an over-estimation of incidence of some causes of mortality [START_REF] Plos | False hopes, unwarranted fears: The trouble with medical news stories[END_REF][START_REF] Frewer | The media and genetically modified foods: evidence in support of social amplification of risk[END_REF]. Estimations of causes of death by the public often bear little relation to official statistics, but do correlate with the frequency of print media reporting [START_REF] Coombs | Newspaper coverage of causes of death[END_REF][START_REF] Frost | Relative risk in the news media: a quantification of misrepresentation[END_REF]. This observation manifests itself as an underestimation of the incidence of common causes of death and an overestimation or rarer causes [START_REF] Frost | Relative risk in the news media: a quantification of misrepresentation[END_REF]. Previous work into the investigation of print media reporting has noted both a poor relationship between the frequency of reporting deaths and mortality rates [START_REF] Frost | Relative risk in the news media: a quantification of misrepresentation[END_REF][START_REF] Kristiansen | Newspaper coverage of diseases and actual mortality statistics[END_REF].

The passive nature of information dissemination coupled with easily understandable articles (unlike many patient information leaflets) may be a key factor in raising the overall awareness of disease by the media [START_REF] Plos | False hopes, unwarranted fears: The trouble with medical news stories[END_REF][START_REF] Williamson | How does the media profile of cancer compare with prevalence?[END_REF][START_REF] Schwitzer | What are the roles and responsibilites of the media in disseminating health information[END_REF][START_REF] Holder | Media advocacy in community prevention: news as a means to advance policy change[END_REF][START_REF] Chapman | Impact of celebrity illness on breast cancer screening: Kylie Minogue's breast cancer diagnosis[END_REF][START_REF] Williamson | Analysis of patient information leaflets provided by a district general hospital by the Flesch and Flesch-Kincaid method[END_REF][START_REF] Durrant | Tobacco in the news: an analysis of newspaper coverage of tobacco issues in Australia, 2001[END_REF]. This opportunistic provision of health information is in addition to advertisements from both government funded institutions and charitable organisations. Moreover, policies of media advocacy, which entail the deliberate use by groups to advance specific causes or concerns, may influence disease coverage [START_REF] Holder | Media advocacy in community prevention: news as a means to advance policy change[END_REF][START_REF] Durrant | Tobacco in the news: an analysis of newspaper coverage of tobacco issues in Australia, 2001[END_REF]. Focused media advertising strategies on a particular disease have been shown to increase public awareness of that disease and improve patient knowledge [START_REF] Durrant | Tobacco in the news: an analysis of newspaper coverage of tobacco issues in Australia, 2001[END_REF]. However, the media reportage of illness can induce negative health consequences [START_REF] Young | Medicine in the popular press: the influence of media on perceptions of disease[END_REF]15]. Media exposure is a strong predictor of posttraumatic stress syndrome and stress reactions after significant events, even in populations not directly affected (e.g. after the September 11 th attack in New York) [START_REF] Vasterman | The role of the media and media hypes in the aftermath of disasters[END_REF][START_REF] Galea | Posttraumatic stress disorder in the general population after mass terrorist incidents: Considerations about the nature of exposure[END_REF][START_REF] Schuster | A national survey of stress reactions after the September 11, 2001, terrorist attacks[END_REF]. Moreover, certain events trigger amplification in perceived risk which is not ultimately accompanied by a commensurate risk increase (e.g.

Chernobyl Disaster [START_REF] Valeska | Chernobyl: poverty and stress pose bigger threat than radiation[END_REF], cancer risk from cell phones [START_REF] Moulder | Cell phones and cancer: what is the evidence for a connection?[END_REF], and anthrax outbreaks [START_REF] Dougall | Media exposure to bioterrorism: Stress and the anthrax attacks[END_REF]).

The aims of this paper are to assess the reportage of the 10 most common causes of death in the UK by the 10 most read daily newspapers and to compare the frequency of mortality in the print media compared to incidence of disease. [START_REF] Griffiths | Leading causes of death in England and Waleshow should we group causes[END_REF].

The searches were performed via each newspaper's online search facility and 'media friendly' terms were used. Where the cause of death was well known to the population, e.g. "breast cancer", the search term was the same as the cause of death. When the cause of death was unfamiliar, e.g. "ischaemic heart disease", then several terms were used (e.g. heart disease, heart attack, cardiac arrest). Only the term yielding the most number of relevant articles was recorded, so as not to duplicate any searches. Table 2 shows the mesh terms used for the searches.

Analysis of the exact content of each article was not possible given the scope of the search.

Cause of Death % of all Deaths

Ischaemic Heart Disease 3 along with the ratio of articles:

deaths (the prevalence of disease in the media). When the numbers of articles are compared to the number of deaths, the media profile of each illness can be seen (figure 1). This media profile shows a ratio of number of articles to the incidence of disease, and represents the over-or under-representation of each illness. A ratio of

Discussion

The media does not exist as a health promotion platform, but it can influence how illness is perceived, in terms of its prevalence, severity and outcomes [START_REF] Plos | False hopes, unwarranted fears: The trouble with medical news stories[END_REF][START_REF] Williamson | How does the media profile of cancer compare with prevalence?[END_REF][START_REF] Schwitzer | What are the roles and responsibilites of the media in disseminating health information[END_REF][START_REF] Mazur | Sounding the global alarm: Environmental issues in the US National News[END_REF][START_REF] Holder | Media advocacy in community prevention: news as a means to advance policy change[END_REF][START_REF] Young | Medicine in the popular press: the influence of media on perceptions of disease[END_REF][START_REF] Frewer | The media and genetically modified foods: evidence in support of social amplification of risk[END_REF]. The media play a critical role in shaping public opinion regarding issues, including infectious disease, illness and death [START_REF] Young | Medicine in the popular press: the influence of media on perceptions of disease[END_REF]. The media is regarded as one of the most important sources of patient information, potentially because it is easily accessible and the public is exposed to it passively [START_REF] Williamson | How does the media profile of cancer compare with prevalence?[END_REF][START_REF] Schwitzer | What are the roles and responsibilites of the media in disseminating health information[END_REF][START_REF] Durrant | Tobacco in the news: an analysis of newspaper coverage of tobacco issues in Australia, 2001[END_REF][START_REF] Williamson | How much vascular disease is reported by the UK media?[END_REF]. The media functions as an interface between the scientific community, government, and the public [START_REF] Cooper | If It Bleeds It Leads"? Attributes of TV health news stories that drive viewer attention[END_REF][START_REF] Sun | The effectiveness in utilizing Chinese media to promote breast health among Chinese women[END_REF]; it therefore has a responsibility to strike a careful balance between raising awareness of issues of public concern and irrationally alarming the public at large [START_REF] Plos | False hopes, unwarranted fears: The trouble with medical news stories[END_REF][START_REF] Cooper | If It Bleeds It Leads"? Attributes of TV health news stories that drive viewer attention[END_REF]. The reportage on health issues is not regulated by any medical representatives, but rather on what is deemed 'newsworthy' -issues that are rare, novel and dramatic rather than those of higher relative risk [START_REF] Plos | False hopes, unwarranted fears: The trouble with medical news stories[END_REF][START_REF] Sun | The effectiveness in utilizing Chinese media to promote breast health among Chinese women[END_REF]. Since alarming content is more common in newscasts than reassuring or neutral content [START_REF] Fischhoff | Risk perception and communication[END_REF], and an estimated 11% of news articles include exaggerated claims [START_REF] Frick | Risk perception, somatization, and self report of complaints related to electromagnetic fields-a randomized survey study[END_REF], the possible impacts of disease being frequently presented in the media deserves attention.

Our results have shown that there is a discrepancy between the number of articles on certain diseases and their associated prevalence. Flu/pneumonia, prostate cancer, Dementia and Breast Cancer are all over-expressed by the print media.

Potential reasons for this include the 'Swine flu' outbreak and coverage of the Libyan Lockerbie bomber, Mr Al-Meghari (accounting for flu/pneumonia and prostate cancer respectively). Despite this topical rise in coverage, there seems to be a genuine over-expression of dementia and breast cancer articles. This increased reporting Terry Pratchett for Alzheimer's disease). For under-reported diseases, there seems to be a genuine lack of articles on CVAs and COPD (the second and fourth largest causes of mortality in the UK). Some medical phrases may be edited out by newspapers to improve the comprehension of any article to the lay public [START_REF] Williamson | Pancreatic cancer in the media: the Swayze shift[END_REF]. This could prove an issue in monitoring how some diseases are recorded by the print media, but our study has tried to minimise this effect by using lay terms where appropriate.

Given the vast number of search results, it was not possible to record the actual content of the newspaper articles. As these search terms could appear anywhere in each article we cannot comment on the accuracy or information content within them.

This study primarily aims to assess the number of articles on each condition and to assess if this accurately reflects incidence of disease. We accept that while the media has some discrepancy on what news issues it reports, coverage is greatly influenced by what 'newsworthy' events are occurring. Despite these limitations, we feel that these results are accurate and are worthy of comment.

Our results suggest two main areas of concern. Firstly, diseases with a high media profile may be considered to be more serious and pose more of a threat than equally serious under-represented infectious diseases. Diseases that are frequently covered by the media are not, however, considered to be 'worse' than those not covered in the media [START_REF] Young | Medicine in the popular press: the influence of media on perceptions of disease[END_REF]. Disproportionate media exposure may have effects on perceptions of disease other than estimates of prevalence, such as disease severity, and whether something is a disease at all [START_REF] Young | Medicine in the popular press: the influence of media on perceptions of disease[END_REF][START_REF] Coombs | Newspaper coverage of causes of death[END_REF][START_REF] Frost | Relative risk in the news media: a quantification of misrepresentation[END_REF]. If increased media frequency can in fact alter perceptions of disease, then this has implications for many aspects of health decision making and, potentially, government funding. Secondly, patients with low media profile diseases may feel stigmatised or isolated as a result of their condition [START_REF] Williamson | How does the media profile of cancer compare with prevalence?[END_REF][START_REF] Frick | Risk perception, somatization, and self report of complaints related to electromagnetic fields-a randomized survey study[END_REF]. The media should be an ideal modality to break down taboos and stigma, potentially by focusing on the 'human element' of disease [START_REF] Williamson | How does the media profile of cancer compare with prevalence?[END_REF][START_REF] Frick | Risk perception, somatization, and self report of complaints related to electromagnetic fields-a randomized survey study[END_REF].

The scope for utilising the media to improve patient education should not be underestimated. Highlighting symptoms of the disease may encourage patients to seek medical consultation at an earlier stage, which could improve outcomes and survival. This is particularly pertinent in cancers as patients are known to be symptomatic for some time prior to presentation [START_REF] Williamson | How does the media profile of cancer compare with prevalence?[END_REF][START_REF] Macleod | Risk factors for delayed presentation and referral of symptomatic cancer: evidence for common cancers[END_REF]. An active policy of media advocacy (collaboration between health care professionals and journalists) could result in articles that are relevant to the population, informative and in a style and format that is easily comprehendible to the lay public [START_REF] Williamson | How does the media profile of cancer compare with prevalence?[END_REF][START_REF] Williamson | How much vascular disease is reported by the UK media?[END_REF]. Professional bodies, such as the Department of Health, the NHS, the Royal Colleges or the Royal Society of Medicine could release articles or information directly to newspapers. This may improve the quality of relevant medical information provided in newspaper articles.

An additional method to enhance the educational content of these articles could focus on targeted advertising -information about the disease in the article could be provided separately and give links to further information sources. This advertising box could be funded by relevant charities. The media has a significant impact on our perceptions of illness and death. Articles can have a positive impact, by acting as a source of health information and breaking down the stigma of disease. However, media coverage may also have a negative impact, with diseases with a high media profile being considered more prevalent and more serious than they are.

As clinicians we need to be aware of the impact that media coverage has on illness for the general population. This may influence how patients seek medical attention and their concerns at consultation. Patients may have a background understanding of their disease (or perceived illness) from the health information provided by the media. In this age of television and internet media it is important to consider the impact of media reporting on public perception of disease, and public health in general. Strategies to improve the educational content of the media may enhance the dissemination of health information via this resource.

  most read daily UK newspapers (The Sun, Daily Mail, The Mirror, The Telegraph, The Times, Daily Express, Daily Star, The Guardian, The Independent and the Financial Times) were assessed for articles relating to the 10 most common causes of death in the UK over a 12-month period (1 st January 2009 -31 st December 2009) [22]. The combined estimated daily circulation of these newspapers is 25.3 million, i.e. 41% UK population [22-23]. The most common causes of death were obtained from the Office for National Statistics and are shown in table 1

  to charity works to promote their respective illnesses (e.g. breast cancer fun runs) and celebrity coverage (e.g. Kylie Minogue for breast cancer and

  The relevant prevalence of disease in the media compared with actual incidence 78x60mm (300 x 300 DPI)

Table 1 :

 1 The incidence of the most common causes of death in the UK[START_REF] Griffiths | Leading causes of death in England and Waleshow should we group causes[END_REF]

	Cause of Death	Search terms used
	Ischaemic Heart Disease	Heart Attack
		Coronary Heart Disease
		Cardiac Arrest
	Cerebrovascular Disease	Stroke
	Flu/Pneumonia	Influenza
		Flu
		Pneumonia
	Respiratory cancer	Throat cancer
	(trachea, bronchus, lung)	Lung cancer
	Chronic obstructive pulmonary disease	COPD
	(COPD)	Chronic obstructive pulmonary disease
		Chronic emphysema
		Chronic bronchitis
	Dementia and Alzheimer's	Dementia
		Alzheimer's Disease
	Colorectal cancer	Bowel cancer
		Colon cancer
		Sigmoid cancer
		Rectal cancer
		Anal cancer
		Colorectal cancer
	Breast cancer	Breast cancer
	Prostate cancer	Prostate cancer
	Heart failure	Heart failure

Table 2 :

 2 Mesh terms used for online newspaper searches

	Results
	Of the 21,561 articles identified over 12 months, refining of the search terms yielded
	18,482 pertinent articles covering the most common causes of death in the UK (table
	1). The most commonly reported conditions were Flu/pneumonia (6525 articles,
	35.2% of total), ischaemic heart disease (3849 articles, 20.8%) and dementia (2577
	articles, 13.9%). The least number of articles related to Chronic Obstructive F Pulmonary Disease (COPD) (95 articles, 0.5% of total) and heart failure (547 o r articles, 3%). The full results are displayed in table
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	8

International Journal of Clinical Practice

International Journal of Clinical Practice


John S Oxford
email: j.oxford@retroscreen.com

Martin Leuwer

Acute sore throat revisited: clinical and experimental evidence for the efficacy of over-the-counter AMC/DCBA throat lozenges

Acute sore throat revisited: clinical and experimental evidence for the efficacy of over-the-counter AMC/DCBA throat lozenges.

Introduction

Recent events of the human influenza (H1N1 virus) pandemic have exposed a central role for sore throat in the basic clinical presentation of the disease [START_REF] Bautista | Writing Committee of the WHO Consultation on Clinical Aspects of Pandemic (H1N1) 2009 Influenza[END_REF]. 'Acute sore throat' is a term often used to describe pharyngitis, tonsillitis and laryngitis that occur for a short period of time. On average, regardless of a pandemic influenza year, an adult may experience 2-3 sore throats over a period of 12 months, whereas children are more susceptible and are likely to experience more sore throat episodes [START_REF] Marshall | Giving advice on sore throats[END_REF], because of their immune naivety. With the imminent re-emergence of flu season in the UK, it would appear an opportune moment to revisit the role of self-prescribed sore throat remedies that, alongside NHS Direct in the United Kingdom (UK), can alleviate pressures on general practitioners. The symptoms of sore throat vary between individuals and include a local mild discomfort with a scratchy-like sensation, swelling, pain with a 'raw' sensation and difficulty in swallowing [START_REF] Kelly | Something for a sore throat please[END_REF]. Most cases of acute sore throat due to upper respiratory tract infections (URTIs), caused by a range of viruses, are generally not serious and are self-limiting, usually improving within 1 week [START_REF] Kelly | Something for a sore throat please[END_REF][START_REF] Campbell | SIGN guidelines and the management of sore throat in community pharmacy[END_REF][START_REF] Parmet | JAMA patient page. Sore throat[END_REF].

A recent report by the Royal College of General Practitioners in the UK documented an agestandardised person prevalence rate of 182 per 10,000 for acute pharyngitis in the year 2007. Furthermore, they reported a patient consultation rate of 182 per 10,000 persons for all ages [START_REF]Weekly Returns Service Annual Prevalence Report[END_REF]. Current recommendations are to avoid unnecessary prescribing of antibiotics [START_REF] Avorn | Antibiotic resistance: synthesis of recommendations by expert policy groups[END_REF][START_REF] Nice | NICE guidelines: Respiratory tract infections -antibiotic prescribing: prescribing antibiotics for self-limiting respiratory tract infections in adults and children in primary care. NICE clinical guideline 69[END_REF][START_REF] Sign | Management of sore throat and indications for tonsillectomy[END_REF][START_REF]Guideline synthesis: Pharyngitis/sore throat[END_REF]. Therefore, an understanding of the leading causes of sore throat and the availability of effective over-the-counter (OTC) treatment options as a recommendation for patients who present at surgeries, are becoming increasingly important.

Causes of acute sore throat

Viruses have been associated with 50-95% of sore throats in adults [START_REF] Summers | Sore throats[END_REF][START_REF] Worrall | Acute sore throat[END_REF], and linked to 70% of sore throats in children between the ages of 5-16 years, and 95% in under 5s [START_REF] Worrall | Acute sore throat[END_REF].

The viral causes of sore throat are numerous and include respiratory viruses such as respiratory syncytial viruses, rhinoviruses and influenza A [START_REF] Oxford | A throat lozenge containing amylmetacresol and dichlorobenzyl alcohol has a direct virucidal effect on respiratory syncytial virus, influenza A and SARS-CoV[END_REF][START_REF] Collier | Human Virology[END_REF]. A global analysis of the prevalence of patients with human influenza (H1N1 virus) reporting sore throat as a symptom ranged from 26% (in the UK) to 39% (in Japan) [START_REF] Bautista | Writing Committee of the WHO Consultation on Clinical Aspects of Pandemic (H1N1) 2009 Influenza[END_REF].

It is possible that bacterial causes may be underestimated and may contribute up to 20% of all sore throat aetiologies [START_REF] Centor | Expand the pharyngitis paradigm for adolescents and young adults[END_REF]. Therefore, it is important that cases of sore throat due to streptococcal infections are correctly identified with appropriate antibiotics prescribed. Other

Pro-inflammatory cytokines and acute sore throat

Irrespective of the cause, a sore throat manifests as irritating symptoms such as pain and irritation, and is most likely to be caused by inflammatory mediators, e.g. bradykinin and prostaglandins, which are released following local responses to cell damage and exert their effect on sensory nerves in the airways [START_REF] Eccles | Mechanisms of symptoms of the common cold and influenza[END_REF]. In addition, pro-inflammatory cytokines have been associated with sickness behaviour [START_REF] Capuron | Cytokines and psychopathology: lessons from interferon-alpha[END_REF], which, in turn, is associated with increased pain sensitivity in cases of microbial infection [START_REF] Capuron | Cytokines and psychopathology: lessons from interferon-alpha[END_REF]. Because most sore throats are infective in nature and sore throat-induced pro-inflammatory cytokines are linked with sickness behaviour, there may be potential implications to the quality of life of sufferers where there is associated viral or bacterial infection. A study in young adults with suspected viral sore throat has demonstrated a high correlation between sore throat and 'sickness' [START_REF] Lindbaek | Clinical course of suspected viral sore throat in young adults: cohort study[END_REF]. Furthermore, it has been found that sore throats have a significant impact on normal daily activities/functions of a patient, including swallowing, talking, eating a meal, sleeping and concentration [START_REF] Mcnally | Rapid relief of acute sore throat with AMC/DCBA throat lozenges: randomised controlled trial[END_REF].

Associated cost burden

Despite the high predominance of viral sore throats over any other causes in adults [START_REF] Summers | Sore throats[END_REF][START_REF] Worrall | Acute sore throat[END_REF], antibiotics are commonly prescribed by physicians for the treatment of acute sore throats [START_REF] Ashworth | Why has antibiotic prescribing for respiratory illness declined in primary care? A longitudinal study using the General Practice Research Database[END_REF][START_REF] Mar | Antibiotics for sore throat[END_REF]. Throughout the 1980s, there was a progressive increase in the overall consumption of antibiotics in the UK [START_REF] Ashworth | Why has antibiotic prescribing for respiratory illness declined in primary care? A longitudinal study using the General Practice Research Database[END_REF][START_REF] Sharland | Antibiotic prescribing in general practice and hospital admissions for peritonsillar abscess, mastoiditis, and rheumatic fever in children: time trend analysis[END_REF]. Although this number fell by 45% in the mid-1990s, in the year 2000, antibiotics were still prescribed to over two-thirds of patients presenting to general practice with respiratory tract infections; 60% of whom had sore throat [START_REF] Ashworth | Why has antibiotic prescribing for respiratory illness declined in primary care? A longitudinal study using the General Practice Research Database[END_REF].

It is now generally recognised that antibiotics have limited efficacy in the majority of patients with acute sore throats [START_REF] Avorn | Antibiotic resistance: synthesis of recommendations by expert policy groups[END_REF][START_REF] Mar | Antibiotics for sore throat[END_REF], and may encourage repeated attendance for future sore throat episodes [START_REF] Little | Reattendance and complications in a randomised trial of prescribing strategies for sore throat: the medicalising effect of prescribing antibiotics[END_REF]. The World Health Organisation guidelines have discouraged the prescribing of antibiotics for the treatment of viral sore throat [START_REF] Avorn | Antibiotic resistance: synthesis of recommendations by expert policy groups[END_REF]. The National Institute for Health and Clinical Excellence (NICE) guidelines in the UK have recommended no or delayed prescribing of antibiotics for minor acute illnesses, including sore throat [START_REF] Nice | NICE guidelines: Respiratory tract infections -antibiotic prescribing: prescribing antibiotics for self-limiting respiratory tract infections in adults and children in primary care. NICE clinical guideline 69[END_REF].

Furthermore, reduced antibiotic prescribing may curb the development of antibioticresistance in the community [START_REF] Summers | Sore throats[END_REF] and reduce the overall cost burden on the healthcare system. Delaying the prescribing of antibiotics (i.e. using antibiotics only if symptoms worsen) in cases of acute sore throat was deemed cost-effective, thereby offering cost savings to the healthcare system [START_REF] Nice | NICE guidelines: Respiratory tract infections -antibiotic prescribing: prescribing antibiotics for self-limiting respiratory tract infections in adults and children in primary care. NICE clinical guideline 69[END_REF]. For example, by adopting the recommended prescribing strategies of delayed or no prescribing, more than £30 can be saved per patient compared with the cost of immediate antibiotic prescribing [START_REF] Nice | NICE guidelines: Respiratory tract infections -antibiotic prescribing: prescribing antibiotics for self-limiting respiratory tract infections in adults and children in primary care. NICE clinical guideline 69[END_REF].

Self-management of acute sore throat

Most cases of acute sore throat can be managed effectively by the patient who does not present with signs of complications such as fever and difficulty in breathing (with the exception of children). The management of acute sore throat revolves around providing relief from existing symptoms (e.g. local pain and inflammation), removal of the underlying causes and the prevention of secondary complications (3). Self-management of non-complicated, simple cases of acute sore throat is possible through the use of analgesic, local anaesthetic, antiseptic and anti-inflammatory agents.

Available OTC sore throat remedies and the different formulations

Compared with oral analgesic treatments, topical remedies such as throat lozenges, gargles and throat sprays [START_REF] Kelly | Something for a sore throat please[END_REF], which are applied directly to the mucous membranes of the mouth or throat, can provide more rapid symptomatic relief in patients with acute sore throat. There are clear differences between the three topical delivery systems in the onset of action and the amount of active ingredients present in the mouth and throat. Throat sprays should ideally produce relatively coarse droplets so that they reach the desired target site. However, a proportion of the spray is immediately swallowed after application [START_REF] Limb | Scintigraphy can be used to compare efficacy of sore throat formulations[END_REF], thus reducing the concentration of active ingredients present in the mouth and throat. In addition, evidence suggests that owing to the gag reflex, gargles are not able to deliver the active ingredients to all areas of the throat and only deliver to the anterior oral cavity [START_REF] Becker | Ear, nose and throat diseases: A pocket reference (Authorised translation) 3rd Ed[END_REF].

Lozenges are placed in the oral cavity where they slowly dissolve to release the active ingredients directly onto the irritated mucosal tissues. As the lozenge dissolves in the mouth, the mouth adopts a reservoir-like role for the distribution of the lozenge contents to the throat [START_REF] Limb | Scintigraphy can be used to compare efficacy of sore throat formulations[END_REF]. Therefore, medicated throat lozenges have the added advantage of being slowreleasing. Furthermore, the portability and convenience of taking lozenges may help to facilitate good adherence/compliance to medication.

A range of active ingredients are used in topical OTC sore throat remedies (Table 1). It is not our intention to present clinical evidence for each of the sore throat treatments available

Important features of some topical OTC sore throat remedies

We propose that an ideal sore throat treatment, or a range of treatment products, should possess the following properties:

• Targets the causes of throat soreness, especially the viral causes and inflammation

• Provides local pain relief, eliminating the associated discomfort in the throat region

• Provides a rapid onset of action from the time that the remedy is taken or administered

• Has a prolonged duration of action, given the actual and patient-perceived prolonged nature of sore throat symptoms

• Be shown to be effective over a range of different types of sore throat (e.g. from the scratchy-like sensation causing local discomfort to the painful sore throats with a 'raw' feeling and to the inflamed, swollen throat types of sore throat)

• Should address the emotional aspects of having a sore throat by helping patients to feel better • Should have a good safety profile

We will now consider these seven characteristics in greater detail.

Targeting the causes of sore throat

Several antiviral drugs of the neuraminidase inhibitor class have been shown to block the replication of influenza in the upper airways [START_REF] Collier | Human Virology[END_REF][START_REF] Gubareva | Influenza virus neuraminidase inhibitors[END_REF], and thereby reduce the symptoms, including those of sore throat. However, although antiviral treatments may have a pivotal place in the treatment of URTIs [START_REF] Roxas | Colds and influenza: a review of diagnosis and conventional, botanical, and nutritional considerations[END_REF], they are bound by several limitations. For example, they are limited by the specific nature of antiviral drugs, the fact that new strains are constantly emerging, the length of time an anti-infective takes to work and the subsequent level of reduction in inflammation that is required before clinical benefits prevail. Moreover, from the viewpoint of a patient, being able to feel well quickly is of primary importance, and so the availability of treatment (i.e. OTC, for easy access and self-management) that targets the underlying causes of sore throat to provide rapid symptomatic relief is key. Ideally, such treatments would target both the viral and inflammatory causes because evidence suggests that antiviral without anti-inflammatory effects have little symptomatic benefit for patients with a cold [START_REF] Johnston | Problems and prospects of developing effective therapy for common cold viruses[END_REF].

Pain relief

Local symptomatic pain relief plays an important role in the management of acute sore throat [START_REF] Roxas | Colds and influenza: a review of diagnosis and conventional, botanical, and nutritional considerations[END_REF]. The influence of pro-inflammatory mediators on the pain sensation of all sore throats regardless of the cause need to be taken into consideration when making treatment choices, and should also be a target for providing symptomatic relief of symptoms, thereby reducing associated inflammation and pain.

The analgesic effect experienced with antiseptic lozenges such as AMC/DCBA throat lozenges was thought to be produced by means of its antiseptic action on bacteria and viruses (Figure 1) [START_REF] Oxford | A throat lozenge containing amylmetacresol and dichlorobenzyl alcohol has a direct virucidal effect on respiratory syncytial virus, influenza A and SARS-CoV[END_REF][START_REF] Richards | Inhibitory activity of lozenges on oral bacteria[END_REF][START_REF] Richards | In vitro evaluation of the antimicrobial activities of selected lozenges[END_REF]. In vitro evidence demonstrated the virucidal effect of AMC and DCBA on a number of viruses associated with common cold/flu [START_REF] Oxford | A throat lozenge containing amylmetacresol and dichlorobenzyl alcohol has a direct virucidal effect on respiratory syncytial virus, influenza A and SARS-CoV[END_REF], and it could be anticipated that reduction of virus infectivity in saliva would reduce virus transmission to others in addition to the immediate clinical benefits of reducing soreness. However, clinical trials and human quarantine experiments would be needed to precisely quantify the antiviral effects of any lozenge in vivo.

However, recent evidence has led to the theory that such pain relief was not merely as a result of antiseptic and demulcent/moisturising action -a possible sodium channel-blocking effect was deemed to be a contributory factor and a viable mechanistic pathway [START_REF] Buchholz | Topical antiseptics for the treatment of sore throat block voltage-gated neuronal sodium channels in a local anaesthetic-like manner[END_REF]. Sodium channels, as mediators of membrane excitability, regulate the sodium permeability of cells during the rapid rising phase of the action potential. These channels play a key role in initiation and transmission of electrical activity throughout the nervous system, with implications for sensory neuron physiology and pathophysiology, and localised inhibition of their function can prevent the perception of pain [START_REF] Priestley | Voltage-gated sodium channels and pain[END_REF][START_REF] Wood | Voltage-gated sodium channels and pain pathways[END_REF]. Therefore, sodium channels are thought to represent key target sites for local anaesthetic agents, such as lidocaine, to exert their analgesic effects.

Based on previous work on sodium channel-blocking properties of phenol derivatives (57-59), we hypothesised that the analgesic effect of antiseptics which carry the aromatic alcohol phenol as the core element (see Figure 2) might actually -at least partly -be due to sodium channel blocking, i.e. direct local anaesthetic-like effects.

In particular, the proposition was examined that the active ingredients AMC, DCBA and hexylresorcinol present in some antiseptic lozenges act in this manner. When the in vitro effect of AMC, DCBA and hexylresorcinol in blocking voltage-operated neuronal sodium channels heterogeneously expressed in human embryonic kidney 293 cells was investigated [START_REF] Buchholz | Topical antiseptics for the treatment of sore throat block voltage-gated neuronal sodium channels in a local anaesthetic-like manner[END_REF], all three agents were found to block voltage-gated sodium channels in a local anaesthetic-like fashion. When AMC and DCBA were investigated separately and in combination, AMC inhibited sodium inward current with a high potency; DCBA, although lower in potency than AMC, exhibited similar blocking potency to the local anaesthetic, lidocaine [START_REF] Buchholz | Topical antiseptics for the treatment of sore throat block voltage-gated neuronal sodium channels in a local anaesthetic-like manner[END_REF]. A combination of the potent channel blocker, AMC, and the reduced potency for sodium channel blockade of DCBA attenuated the effects of AMC, possibly as a result of competitive binding. This may have in vivo benefits of limiting the overall local anaesthetic effect known as a 'ceiling' effect, so as to avoid over-numbing without compromising pain relief [START_REF] Buchholz | Topical antiseptics for the treatment of sore throat block voltage-gated neuronal sodium channels in a local anaesthetic-like manner[END_REF].

In addition, real-life patient experiences reported during clinical trials have demonstrated that AMC/DCBA-containing lozenges exert significantly greater reductions in mean throat discomfort levels [START_REF] Berry | Developments in acute sore throat relief -efficacy and sensorial benefits of medicated lozenges[END_REF], severity of throat soreness [START_REF] Mcnally | Rapid relief of acute sore throat with AMC/DCBA throat lozenges: randomised controlled trial[END_REF][START_REF] Berry | Developments in acute sore throat relief -efficacy and sensorial benefits of medicated lozenges[END_REF][START_REF] Marazzi | Strepsils anaesthetic lozenges versus control Strepsils lozenges in the relief of moderate-to-severe sore throat: a double-blind, cross-over, multiple-dose, randomized study[END_REF][START_REF] Wade | A randomized, double-blind, parallel-group, placebo-controlled, multipledose study of the efficacy of Strepsils lozenges in the relief of acute sore throat[END_REF], offering greater pain relief [START_REF] Mcnally | Rapid relief of acute sore throat with AMC/DCBA throat lozenges: randomised controlled trial[END_REF][START_REF] Berry | Developments in acute sore throat relief -efficacy and sensorial benefits of medicated lozenges[END_REF][START_REF] Marazzi | Strepsils anaesthetic lozenges versus control Strepsils lozenges in the relief of moderate-to-severe sore throat: a double-blind, cross-over, multiple-dose, randomized study[END_REF][START_REF] Wade | A randomized, double-blind, parallel-group, placebo-controlled, multipledose study of the efficacy of Strepsils lozenges in the relief of acute sore throat[END_REF] and easing of difficulty in swallowing [START_REF] Mcnally | Rapid relief of acute sore throat with AMC/DCBA throat lozenges: randomised controlled trial[END_REF] to sore throat sufferers compared with non-medicated placebo lozenges. Furthermore, the analgesic effects of AMC/DCBA throat lozenges were clinically meaningful compared with non-medicated lozenges [START_REF] Mcnally | Rapid relief of acute sore throat with AMC/DCBA throat lozenges: randomised controlled trial[END_REF], and significant improvements in functional impairment scores were observed for swallowing, talking and eating a meal [START_REF] Mcnally | Rapid relief of acute sore throat with AMC/DCBA throat lozenges: randomised controlled trial[END_REF]. Importantly, this evidence suggests that effective OTC treatments are available that not only provide effective relief of the physical symptoms, but also improve functional impairment, thus allowing patients to re-engage in their daily activities and return to their everyday lives [START_REF] Mcnally | Rapid relief of acute sore throat with AMC/DCBA throat lozenges: randomised controlled trial[END_REF].

Speed of action

When evaluating the suitability of sore throat remedies, the simple demulcent benefits should not be overlooked because demulcents, such as glycerin, honey and sugar (which form the base of throat lozenges), act to soothe the throat and reduce the irritation (2). In addition, the increased production of saliva induced by the sucking action required with lozenges that becomes evident after 1 minute (63) provides lubrication to the throat to soothe inflammation [START_REF] Marshall | Giving advice on sore throats[END_REF]. Saliva production may also flush the offending microbes from the throat surface [START_REF] Marshall | Giving advice on sore throats[END_REF]. Furthermore, the antiviral and antifungal constituents of saliva may protect tissues by targeting microbes, encouraging soft tissue repair, maintaining an ecological balance in the oral region and maintaining an adequate pH [START_REF] Mandel | The functions of saliva[END_REF]. Previous research has shown that AMC/DCBA-containing throat lozenges administered to healthy volunteers promote saliva production [START_REF] Wade | Bioavailability and efficacy of active lozenges in the relief of sore throat pain[END_REF].

Scintigraphy studies have highlighted transit and deposition sites in the throat and have shown that the lozenge formulation can facilitate the delivery of active ingredients to the throat at a similar rate to a spray and at a greater rate than a gargle, and at a concentration that was maintained for longer than the spray or gargle [START_REF] Limb | Scintigraphy can be used to compare efficacy of sore throat formulations[END_REF].

In general, rapid sensorial effects (i.e. relief that is soothing and comforting) can impact the overall speed of treatment benefit, and is thus key to the perceived efficacy of a sore throat remedy. However, the sensorial effects will also need to be supported by rapid analgesic relief provided by the active ingredients -this separation of effect can be seen with AMC/DCBA throat lozenges [START_REF] Mcnally | Rapid relief of acute sore throat with AMC/DCBA throat lozenges: randomised controlled trial[END_REF]. Furthermore, because the natural clinical course of sore throats is often 6-8 days [START_REF] Lindbaek | Clinical course of suspected viral sore throat in young adults: cohort study[END_REF], untreated patients often endure persistent pain, irritation or other unpleasant sensory experiences over a prolonged period of time.

The duration of action

Therefore, having a long duration of action is an essential prerequisite of any remedy used.

Limb et al. have demonstrated that lozenges offer a relatively prolonged activity [START_REF] Little | Reattendance and complications in a randomised trial of prescribing strategies for sore throat: the medicalising effect of prescribing antibiotics[END_REF].

Gargles are usually gargled in the mouth for approximately 30 seconds and then are expelled whereas sprays are swallowed soon after application, but lozenges take approximately 6-9 minutes to dissolve in the mouth upon sucking [START_REF] Wade | Bioavailability and efficacy of active lozenges in the relief of sore throat pain[END_REF]. Scintigraphy research has shown that lozenges are an ideal vehicle for sore throat treatment owing to their reservoir-like action, offering rapid and prolonged delivery of active ingredients [START_REF] Limb | Scintigraphy can be used to compare efficacy of sore throat formulations[END_REF]. Furthermore, studies have demonstrated that continued use of AMC/DCBA throat lozenges over a 3-day period provides significantly greater improvements in throat soreness, faster pain relief and greater easing of difficulty in swallowing compared with non-medicated lozenges [START_REF] Mcnally | Rapid relief of acute sore throat with AMC/DCBA throat lozenges: randomised controlled trial[END_REF].

Effectiveness over a range of different types of sore throat

Sore throats exhibit themselves in different ways depending on the individual and the causative factors. A combination of antiseptic, analgesic and anti-inflammatory properties of medicated lozenges, and stimulation saliva production are important attributes for a sore throat lozenge.

Helping patients to feel better

McNally et al. have recently documented the beneficial effects of a lozenge and noted that a significantly greater number of patients who took the medicated throat lozenges felt better compared with those who took the non-medicated lozenge (65% vs 26%, respectively; [START_REF] Mcnally | Rapid relief of acute sore throat with AMC/DCBA throat lozenges: randomised controlled trial[END_REF]. This begins to address the emotional aspects of having a sore throat. When patients feel better, they can get back to and carry on with their everyday lives.

Safety profile

The literature available on topical OTC sore throat treatments demonstrates a good safety profile, with only very minor self-limiting adverse effects, such as headaches and coughing being reported. However, a systematic review is warranted to further evaluate this.

Additionally, it is important to note that patients should take care when drinking hot beverages if using strong anaesthetics, because the local numbing effect may result in patients underestimating the exact temperatures.

Conclusions

Sore throat is considered a minor ailment but results in considerable suffering for the patient who then seeks remedial action, often at the expense of the healthcare system. A reduction in antibiotic prescribing, especially for respiratory conditions such as sore throat, is currently on the agenda of many global healthcare services to minimise bacterial resistance and unnecessary exposure of patients to potential side effects [START_REF] Avorn | Antibiotic resistance: synthesis of recommendations by expert policy groups[END_REF][START_REF] Nice | NICE guidelines: Respiratory tract infections -antibiotic prescribing: prescribing antibiotics for self-limiting respiratory tract infections in adults and children in primary care. NICE clinical guideline 69[END_REF][START_REF] Sign | Management of sore throat and indications for tonsillectomy[END_REF][START_REF] Ashworth | Why has antibiotic prescribing for respiratory illness declined in primary care? A longitudinal study using the General Practice Research Database[END_REF], which in turn reduces costs. In the UK, NHS Direct has encouraged self-diagnosis and along with the mild symptoms (including sore throat) experienced by most, the extensive OTC range of medicines, such as analgesics and sore throat lozenges has played an important clinical role in communities around the world.

An 'ideal' OTC treatment for sore throat should have a minimum set of features that would render it clinically effective in providing pain relief and have additional benefits, such as those of sensorial stimulation. These 'ideal' characteristics -targeting the underlying causes, providing pain relief, having a rapid onset of action or prolonged duration and being effective over a range of different sore throat types such that the patient feels better after treatmentshould be borne in mind when making a treatment recommendation to patients, given the evidence available.

  throat include environmental influences, such as temperature changes, low humidity, smoking, air pollution and a reaction to allergens, among other factors[START_REF] Avorn | Antibiotic resistance: synthesis of recommendations by expert policy groups[END_REF].

  , we will use amylmetacresol and 2,4-dichlorobenzyl alcohol (AMC/DCBA)containing throat lozenges as a case example because of the availability of recently published data/evidence.

  received research contract funding from the former Boots Healthcare International, now known as Reckitt Benckiser Healthcare International, to investigate virucidal properties of lozenges. Professor J.S. Oxford has received lecture fees and travel grants from Reckitt Benckiser Healthcare International, but not related to the writing of this review article. Professor M. Leuwer has received research contract funding from Reckitt Benckiser Healthcare International to investigate the effects of active ingredients in lozenges on voltage-operated sodium channels; no personal funding was received for the preparation of this article. Reckitt Benckiser Healthcare International is the manufacturer of Strepsils.

Figure 1 : 19 Figure 2 :

 1192 Figure 1: The mechanism of action of AMC/DCBA-induced destruction of viruses (13)

Table 1 : Main active ingredients present in some typical OTC sore throat treatments and their mode of action

 1

			Products
			containing
		Formulation	these
	Active ingredient	type(s)	ingredients*	Mechanism of action	References
				Local anaesthetic; acts on	Weiser and Wilson, 2002
				the neuronal voltage-gated	(26); Schutz et al, 2002
	Ambroxol			Na channels in sensory	(27); Fischer et al, 2002
	hydrochloride	Lozenges	Mucoangin™	neurones (29)	(28)
				Antibacterial; antiviral; local
				anaesthetic; blocks voltage-
				gated Na channels in a
	Amylmetacresol	Spray, lozenges	Strepsils ®	local anaesthetic-like manner	Buchholz et al, 2009 (29)
		Cream, gel,	Merocaine ® ; Tyrozet ® ,
	Benzocaine (ethylaminobenzoate)	spray, lozenges	Chloraseptic, Dequacaine ®	Local anaesthetic (ester-type)	Dempster, 1988 (30); Kagan et al, 1982 (31)
					Froom and Boisseau,
					1979 (32); Wethington,
		Throat		Non-steroidal anti-	1985 (33); Young, 1987
		spray,		inflammatory drug (NSAID);	(34); Chudoba, 1983 (35);
		gargles,	Tantum Verde,	some local anaesthetic	Whiteside, 1982 (36);
	Benzydamine HCl	lozenges	Difflam	activity	Agarwal et al, 2006 (37)
	Cetylpyridinium chloride	Lozenges, throat sprays	Merocets ® , Merocaine ® ,	Antibacterial	Richards et al, 1996 (38); Zejdl et al, 1990 (39)
				Antibacterial; antiviral; local
				anaesthetic; blocks voltage-
				gated Na channels in a
	2,4-dichlorobenzyl alcohol	Spray, lozenges	Strepsils ®	local anaesthetic-like manner	Buchholz et al, 2009 (29)
		Sprays,			Benrimoj et al, 2001 (40);
	Flurbiprofen	gargle, lozenges	Strefen ®	Anti-inflammatory; NSAID	Watson et al, 2000 (41); Blagden, 2002 (42)
		Throat
		spray, mouth
		spray,			Bokor, 1996 (43);
	Hexetidine	lozenges	Hexoral	Antiseptic effects	Klingbeil, 1982 (44)
				Antiseptic; local
				anaesthetic; blocks voltage-gated Na channels in a	Martindale 35 th Ed, 2007
	Hexylresorcinol	Lozenges	Strepsils Extra ®	local anaesthetic-like manner	(45); Buchholz et al, 2009 (29)
					Martindale 35th Ed, 2007
		Spray, gel,	Strepsils Plus ® ,	Local anaesthetic (amide-type): blocks voltage-gated	(45); Leuwer et al, 2004 (46); Buchholz et al, 2009
	Lidocaine HCl	lozenges	Dequaspray	Na channels	(29)
				Antibacterial; hydrolysis of
				glycosidic linkage of
	Muramidase HCl	Lozenges,		peptoglycan in bacterial cell	Bienen and Raus, 1981
	(lysozyme)	mouth rinses Lysopaine	walls	(47)
				Antibacterial, local	Al-Bayati, 2009 (48); Martindale 35 th Ed, 2007
	Volatile oils (i.e.			anaesthetic; blocks voltage-	(45); Haeseler et al, 2002
	menthol)	Lozenges	Halls, Lockets	gated Na channels

Acknowledgments

The authors would like to thank Quyen Chu, PhD (a member of the European Medical Writer's Association), who was funded by Reckitt Benckiser Healthcare International for editorial support during the preparation of this manuscript.