R Naslain

J Lamon

A Guette

X Bourrat

F Langlais

R Pailler

F Rebillat

S Jacques

C Robin-Brosse

S Goujard

J M Jouin

THE MICROCOMPOSITE CONCEPT IN THE FIELD OF CERAMIC MATRIX COMPOSITES: ADVANTAGES AND LIMITS

Keywords: Microcomposite, Nicalon, SiC/SiC, Interphase, Pyrocarbon, BN, Mechanical behavior, Oxidation

The microcomposite is the elementary cell of a ceramic matrix composite. It consists of one single straight filament coated with a layer of interphase and embedded in the matrix. SiC/SiC microcomposites are prepared by chemical vapor deposition from Nicalon fibers and gaseous precursors. They have two advantages: they can be processed in a very short time and the modelling of their physicochemical and mechanical behavior is relatively straightforward. SiC/SiC microcomposites display a non-linear mechanical behavior under tensile loading conditions similar to that of practical composites. The interfacial parameters have been derived from the tensile stress-strain curves or from push-in/ out data. The matrix crack deflection modes have been directly identified by transmission electron microscopy. Thermal residual stresses have been calculated either analytically or by the finite element method and tentatively measured by X-ray diffraction. The oxidation of SiC/C/SiC microcomposites has been modelled analytically. The oxidation resistance is improved when the PyCinterphase is replaced by (PyC-SiC) n multilayers or by layered materials containing boron (such as B(C) or BN). The limits of the microcomposite concept are discussed.

INTRODUCTION

SiC/SiC composites have been designed for applications at high temperatures in oxidizing atmospheres, e.g. in the aeronautic field. They usually consist of a complex multidimensional fiber architecture which is infiltrated via liquid or gas phase routes, with a precursor of the SiC-matrix. In the so-called CVI-process, this precursor is a gaseous CH3SiCl3 (MTS)/H2 mixture [START_REF] Naslain | CVI composites[END_REF]. SiC/SiC composites display a non-brittle mechanical behavior when the bonding between the SiC-based fibers and the SiC-matrix has been properly optimized [START_REF] Lamicq | SiC/SiC composite ceramics[END_REF]. The control of the fiber-matrix bonding is usually achieved through the use of a thin interphase, such as a layer of pyrocarbon (PyC) or hex-BN [START_REF] Naslain | Fiber-matrix interphases and interfaces in ceramic matrix composites processed by CVL Composites Interfaces[END_REF]. When exposed to oxidizing atmospheres, SiC/SiC composites experience complex phenomena which may limit their lifetime [START_REF] Naslain | SiC-matrix composites for thermostructural applications: effect of the environment[END_REF][START_REF] Heurtevent | Matériaux multicouches nanoséquencés (PyC/SiC) n : Application en tant qu'interphases dans les composites thermostructuraux[END_REF][START_REF] Jacques | High temperature lifetime in air of SiC/C(B)/SiC microcomposites prepared by LPCVD[END_REF].

The study of the processing conditions, of the mechanical behavior and of the effect of the environment for these rather complex materials requires numerous experiments and samples, and can be time consuming. Part of these issues can be treated by cons ide ring model composites, such as the so-called microcomposites. A microcomposite is the unit cell of any ceramic matrix composite (CMC). It consists of one single straight fiber, e.g. a Si-C-O Nicalon fiber (NLM 202 fibers from Nippon Carbon, Japan), coated with a sub-µm layer of the interphase material such as PyC, and finally embedded in the ceramic matrix (here, SiC). SiC/SiC microcomposites are processed by chemical vapor deposition according to a procedure similar to that used for real composites but in a shorter time.

The aim of the present contribution is to show that the basic phenomena controlling the mechanical behavior of CMCs, such as matrix microcracking, crack deflection at the fibermatrix interfaces, thermal residual stresses and oxidation can be studied on microcomposites, with considerable time saving. Another objective is to show that conversely, the microcomposite approach has also some drawbacks and limits, since it does not take into account the effect of the surrounding fibers.

II. PROCESSING

SiC/SiC microcomposites are processed by chemical vapor deposition (CVD) according to a procedure closely related to that used in the CVI-processing of real nD-SiC/SiC composites (with n ≥ 2), the reactants and the furnace being the same [START_REF] Naslain | CVI composites[END_REF]. First, in the preparation of a microcomposite, the substrate on which deposition occurs is a straight single filament (≈ 14 µm in diameter, for Nicalon fibers) extracted from a fiber tow. As such a substrate is extremely fragile, it is mounted on a ceramic holder with high temperature cement, to be easily handled (Fig. la). Secondly, during the processing of microcomposites, the single filament substrates are directly in the reactant gas flow (CVD-mode) whereas in that of real composites, deposition occurs in the porosity of a fiber preform (CVI-mode). As a result, the reactant mass transfer to the substrate, the composition of the gas phase near the substrate and hence the deposition rate, are very different. When prepared under optimized conditions, SiC/SiC microcomposites consist of uniaxial concentric shells with a relatively smooth external surface, volume fractions similar to those of real composites and an overall outer diameter of ≈ 20 µm for Vf ≈ 50% (Fig. lb). They can be assimilated to pure 1D-composites with a circular cross-section, in a first approximation.

III. MECHANICAL CHARACTERIZATION

With an overall diameter of ≈ 20 µm, a Nicalon/SiC microcomposite (Vf ≈ 50%) can be tensile tested according to the procedure developed for single filament fibers [START_REF] Villeneuve | Tensile testing at high temperatures of ex-PCS Si-C-O and ex-PCSZ Si-C-N single filaments[END_REF]. For room temperature tensile tests, the microcomposite is first mounted on a window paper (or PVC) frame (gauge length L = 10 or 25 mm) (Fig. 2a). After gripping, the sides of the window frame are cut and the microcomposite is tensile loaded at a constant strain rate (0.1% per min), with a table-model testing machine equipped with a high precision load cell (2N maximum), the grip displacement being measured with a LVDT high resolution transducer (10 mV for 1 µm). An example of tensile curve recorded with unloading-reloading cycles is shown in Fig. 2b for a 1D-Nicalon/BN/SiC microcomposite.

The tensile stress-strain curve of a Nicalon/SiC microcomposite [START_REF] Lamon | Determination of interfacial properties in ceramic matrix composites using microcomposite specimens[END_REF][START_REF] Lamon | Micromechanical and statistical approach to the behavior of CMCs[END_REF][START_REF] Jacques | C(B) materials as interphases in SiC/SiC model microcomposites[END_REF][START_REF] Rebillat | Interfacial characterization of SiC/BN/SiC composites through tensile tests on microcomposites and on 2D composites and through single fiber push-out tests[END_REF] exhibits the same general features as those observed for the corresponding 2D-Nicalon/SiC practical composites [START_REF] Naslain | SiC/SiC composites: thermostructural materials for applications in severe environments[END_REF], namely: (i) a linear elastic domain, (ii) a non-linear domain induced by damage phenomena, including matrix micro-cracking and fiber-matrix debonding, and (iii) ultimate failure that occurs with more or less significant fiber pull-out length (Fig. 2b). Furthermore and as shown by various experimental data [START_REF] Rebillat | Interfacial characterization of SiC/BN/SiC composites through tensile tests on microcomposites and on 2D composites and through single fiber push-out tests[END_REF] for a series of Nicalon/BN/SiC microcomposites with BN-interphases deposited in different conditions (Fig. 3) and also by a model of the stressstrain behavior [START_REF] Lamon | Influence of interfacial characteristics on the nonlinear deformations of ceramic matrix composites[END_REF], the shape of the tensile curve in the non-linear domain, the number of matrix microcracks, N, the debond length, Id and the fiber pull-out at failure, also depend on the fiber-matrix bonding. However, there are also some noticeable differences with respect to real 2D-composites. In a microcomposite, there is no averaging effect (since it contains only one fiber) as opposed to 2D-real composites where a very large number of fibers contribute to the overall mechanical behavior. As a result, there is a certain scatter in the experimental data, and fiber interactions are discarded.

An important advantage of the microcomposite lies in the fact that its mechanical behavior can be modelled relatively easily (it is a pure 1D-composite consisting of uniaxial concentric shells of fiber, interphase and dense SiC-matrix). Thus, the multiple cracking of the matrix and the fiber failure have been modelled in 1D-Nicalon/PyC/SiC microcomposites according to a statistic/probabilistic approach taking into account the fiber matrix bonding (the interfacial parameters being the debond length, Id and interfacial shear stress ) [START_REF] Lamon | Influence of interfacial characteristics on the nonlinear deformations of ceramic matrix composites[END_REF]. Weak interfaces (i.e. large Id and small ) limit the matrix microcracking process and decrease the stress at saturation whereas for stronger interfaces (small Id and large ) the matrix microcracking is limited by fiber failure (with a large number of cracks and a higher stress at saturation). The Weibull statistieal parameters pertinent to the SiC CVI matrix (mM = 4.9 and σoM = 2.9 MPa m 1.03 ) are derived from the distribution of the matrix microcracking stresses assessed through a microcomposite tensile test [START_REF] Lamon | Micromechanical and statistical approach to the behavior of CMCs[END_REF]. In a similar manner the fiber-matrix interfacial parameters (which are key parameters for optimizing the processing conditions), namely the interfacial shear stress, , the debond energy, Gic, and the debond length, Id, can be derived from the analysis of the stress-strain curve and unloading-reloading cycles [START_REF] Lamon | Microcomposite test procedure for evaluating the interface properties of ceramic matrix composites[END_REF]. For the 1D-Nicalon/BN /SiC microcomposite specimens prepared from as-received fibers and whose tensile curves are shown in Fig. 3a, the number of matrix microcracks and the interfacial parameters fall in the following ranges: 9 < N < 55; 3 <  < 10 MPa; 0 < Gic < 14 J/m 2 and 150 < Id < 600 µm [START_REF] Lamon | Microcomposite test procedure for evaluating the interface properties of ceramic matrix composites[END_REF]. Finally, the stress fields in the fiber, the interphase and the SiC-matrix, along the fiber axis can be derived from SEM measurements of the in-situ fiber failure stress (mirror radius) and fiber pull-out length. As shown in Fig. 3b for 1D-Nicalon/BN/SiC microcomposites,  displays a very high value near the matrix microcrack plane then it decreases exponentially to become very low beyond a 30 µm distance (the mean value derived from integration being ≈ 10 MPa). These results suggest a very short debond [START_REF] Rebillat | Experimental determination of the stress field in fiber-matrix interphases of microcomposites[END_REF].

Push-in and even push-out tests can also be performed on microcomposites. However, such tests are difficult to conduct and require a specific specimen preparation [START_REF] Rebillat | Interfacial characterization of SiC/BN/SiC composites through tensile tests on microcomposites and on 2D composites and through single fiber push-out tests[END_REF]. First, the microcomposite is embedded in a stiff enough medium which can be a glass or a ceramic cement. Then, a slab is cut with a diamond saw in a direction perpendicular to the microcomposite axis and polished, the final thickness of the slab being of the order of 200 µm. In a last step, the fiber is pushed-in or pushed-out (depending on the fiber/matrix bonding and slab thickness) with a diamond cone and the interfacial parameters are extracted from the stressdisplacement curve according to the models which have been developed for real composites (Fig. 4). Although there is a certain scatter in the data and some difference in the interfacial parameters values (depending on the model used), a relatively good agreement is generally observed between the interfacial parameters extracted from tensile test data and push-in/ out data for the microcomposites, on the one hand, and between those derived from the microcomposites and the real composites, on the other hand [START_REF] Rebillat | Interfacial characterization of SiC/BN/SiC composites through tensile tests on microcomposites and on 2D composites and through single fiber push-out tests[END_REF][START_REF] Kerans | Fiber-matrix interface properties of single-fiber microcomposites as measured by fiber pushin tests[END_REF].

Thermal residual stresses (TRS), which arise during processing from thermal expansion mismatch, can be calculated analytically or according to a finite element approach [START_REF] Lamon | Micromechanical and statistical approach to the behavior of CMCs[END_REF][START_REF] Bobet | Thermal residual stresses in ceramic-matrix composites, Part 1axisymmetrical model and finite element analysis[END_REF]. Although there is some uncertainty about the thermomechanical properties of pyrocarbon interphase, the calculations suggest that the interphase in SiC/PyC/SiC microcomposite is subject to tensile radial TRS, a feature which is consistent with its function of mechanical fuse (Fig. 5). Preliminary experiments aiming at measuring the TRS in microcomposite by X-ray diffraction have been reported [START_REF] Bobet | Thermal residual stresses in ceramic-matrix composites, Part 2-experimental results for model materials[END_REF].

The characterization of the matrix crack deflection process in microcomposites, by transmission electron microscopy (TEM) is possible. Since the cracks are deflected parallel to the fiber surface, the observation must be conducted on longitudinal thin foils. The preparation of such thin foils is difficult and it requires a specific procedure which has been depicted elsewhere [START_REF] Jacques | Characterization of SiC/C(B)/SiC microcomposites by transmission electron microscopy[END_REF]. An example of deflected matrix crack in a Nicalon/C(B)/SiC microcomposite is shown in Fig. 6. In this specimen, the interphase exhibited a composition gradient, the B atomic concentration in the pyrocarbon increasing from 0 (sublayer 1) to 33% (sublayer 5). The matrix crack has been deflected between sublayers 2 and 3 as the result of a change in the texture of the C(B) sublayers [START_REF] Jacques | Characterization of SiC/C(B)/SiC microcomposites by transmission electron microscopy[END_REF].

IV. EFFECT OF THE ENVIRONMENT

Below 1100-1200°C (the limit of stability of the Nicalon fiber), the lifetime of SiC/SiC composites in air is controlled by oxidation phenomena [START_REF] Naslain | SiC-matrix composites for thermostructural applications: effect of the environment[END_REF]. The oxidation of a 1D-SiC/PyC/SiC microcomposite can be modelled analytically (owing to its simple geometry). Two phenomena are in competition: (i) the heterogeneous chemical reactions (the oxidation of the PyC interphase occurs with an evolution of CO/CO2 gaseous species and the formation of an annular pore around the fiber whereas the oxidation of the fiber and the matrix takes place with formation of silica layers on the pore wall) and (ii) the mass transfer of oxygen and CO/CO2 along the pore, by diffusion [START_REF] Filipuzzi | Oxidation mechanisms and kinetics of 1D-SiC/C/SiC composite materials: 2-Modelling[END_REF]. At high temperatures (1100-1200°C), silica (whose formation rate is fast) seals pore entrance and impedes the in-depth gasification of the PyC-interphase and oxygen diffusion (Fig. 7). Under such conditions, the material is self-healing. Conversely, at low temperatures (500-700°C), the oxidation rate of carbon is already fast whereas the formation rate of silica is negligible. As a result, the oxidation of the PyC-interphase proceeds in-depth. Hence, the degradation of the material is more significant at low temperatures. Furthermore, it is enhanced when the SiC-matrix is microcracked (the micro cracks forming new pathways for oxygen diffusion), i.e. when the composite is loaded beyond the limit of linearity.

The effect of an oxidizing atmosphere on the lifetime under load of SiC/SiC composite, can be easily studied through experiments conducted on microcomposites, as shown in Fig. 8a. A constant load is applied to each microcomposite and an electronic device measures the time at failure. The lifetime within the temperature range 500-700°C is improved when the PyC homogeneous interphase is replaced by a (PyC-SiC)n multilayer in which the thickness of the PyC sublayers is lowered [START_REF] Heurtevent | Matériaux multicouches nanoséquencés (PyC/SiC) n : Application en tant qu'interphases dans les composites thermostructuraux[END_REF]. Under such conditions, the in-depth diffusion of oxygen becomes more difficult and the protection by silica more effective. It can also be increased by introducing boron in the interphase (by simple doping or as a layered compound such as BN). The oxidation of boron yields an oxide, B2O3, which remains in condensed state up to at least 1100°C and is known for its healing properties (it fills the microcracks as the y are formed). An example of lifetime curves is shown in Fig. 8b for three kinds of microcomposites with different interphases, which have been exposed in air at a stress higher than the limit of linearity. The lifetimes (corresponding to 50% of the microcomposites broken) are: 24 h for the 1D-Nicalon/PyC/SiC microcomposite (with a PyC thickness of 0.4 µm), 72 h and 120 h for those with interphases of same overall thickness but containing boron (with different concentration gradients for A and A') [START_REF] Jacques | High temperature lifetime in air of SiC/C(B)/SiC microcomposites prepared by LPCVD[END_REF][START_REF] Jacques | C(B) materials as interphases in SiC/SiC model microcomposites[END_REF].

CONCLUSION

From the data which have been presented and discussed in sections 2 to 5, the following conclusions can be drawn: (i)-the microcomposite is the elementary unit cell of a CMC, say a SiC/SiC composite. It contains the three constituents of the composite, i.e. the fiber and the matrix bonded via the interphase as in a real composite. Hence it can be used as a model composite to study the basic phenomena which control the behavior of a CMC from a physico-chemical and mechanical standpoint.

(ii)-the microcomposite has two important advantages versus real composites. First, it can be prepared in a very short time according to the same processing route as that used for real composite (e.g. CVD/CVI). Second, its very simple geometry renders rather straightforward the modelling of the behavior of the material. Hence, the search for correlation between processing, microstructure and properties is much easier. (iii)-conversely, the use of micro composite has also some limitation. First, the same processing conditions when used to prepare microcomposites and real composites may yield materials with different microstructures, since in the gas phase route the former are processed under CVDconditions and the latter under CVI-conditions. As a result, some adjustment of the processing parameters is necessary when moving from the microcomposites to the real composites and vice versa. Second, the microcomposite does not take into account the effect of the surrounding fibers on the elementary cell. For this reason, complementary experiments on minicomposites (infiltrated fiber tows) are useful. (iv)-taking into account the advantages and limits mentioned above, the microcomposite approach is very appropriate to study the basic phenomena involved in CMCs such as: the fiberinterphase-matrix reactions, the load transfer function, the mechanical fuse function, the relief of TRS by the interphase, the chemical reactions with the atmosphere and its effect on the mechanical behavior. Conversely, in specific domains such as the mechanical properties, the microcomposite is not always representative of real composites and complementary experiments at a larger scale are often necessary.

FIGURESFig. 1 .

 1 FIGURES

Fig. 2 .

 2 Fig. 2. Tensile test on 1D-Nicalon/BN/SiC microcomposite: (a) specimen holder, (b) tensile curve.

Fig. 3 .

 3 Fig. 3. Tensile tests at room temperature on 1D-Nicalon/BN/SiC microcomposites: (a) for specimens prepared from as-received fibers and BN -interphases deposited under different conditions and (b) stress fields along the fiber-axis (Lg/2N: mean half length of the matrix blocks associated with matrix microcracks) [15].

Fig. 4 .

 4 Fig.4. Push-out curves for Nicalon/BN/SiC micro-and real-composites according to[START_REF] Rebillat | Interfacial characterization of SiC/BN/SiC composites through tensile tests on microcomposites and on 2D composites and through single fiber push-out tests[END_REF]

Fig. 6 .

 6 Fig.6. TEM-image of matrix crack deflection (arrows) in a Nicalon/C(B)/SiC microcomposite[START_REF] Jacques | Characterization of SiC/C(B)/SiC microcomposites by transmission electron microscopy[END_REF]

Fig. 7 .Fig. 8 .

 78 Fig. 7. Simulation of the oxidation of the PyC-interphase in a 1D-Nicalon/PyC/SiC microcomposite (PO 2 = 100 kPa; T = 1200°C; e PyC = 0.l µm)[START_REF] Filipuzzi | Oxidation mechanisms and kinetics of 1D-SiC/C/SiC composite materials: 2-Modelling[END_REF]

ACKNOWLEDGEMENTS

This work has been supported by the Ministry of National Education and Research, CNRS and SEP. The authors acknowledge the contribution of different PhD students including J.L. Bobet, L. Filipuzzi, L. Guillaumat, F. Heurtevent and N. Lissart. They are also indebted to F. Lamouroux, J. Forget and C. Dupouy for their assistance in the preparation of the manuscript.


Eve Bureau-Point
email: eve.bureau-point@univ-amu.fr

Carine Baxerres
email: carine.baxerres@ird.fr

Sena Chheang
email: sena_chheang@uhs.edu.kh

SELF-MEDICATION AND THE PHARMACEUTICAL SYSTEM IN CAMBODIA

Keywords: Cambodia, autonomy, pharmaceutical system, self-medication. Media teaser: How does the Cambodian pharmaceutical system shape practices of selfmedication? Bionotes

Based on an ethnographic study of the Cambodian pharmaceutical system conducted in an urban and a rural setting between January 2015 and June 2016, we report on the complex dynamics surrounding the issue of self-medication in that country. We describe the history of the circulation of pharmaceuticals in Cambodia, and we discuss the contemporary relationship individuals have with these medicines and with those who distribute them. We illustrate the specific dynamics of the pharmaceuticalization of Cambodian society, where private drug vendors are playing a key role.

Self-medication refers to an individual's behavior regarding the act of taking a remedy, whether pharmaceutical or not, on one's own volition. For the World Health Organization (WHO), self-medication-along with hygiene, nutrition, and lifestyle-is part of self-care; in other words, it is "what people do for themselves to establish and maintain health, prevent and deal with illness" [START_REF] Who | The role of the pharmacist in self-care and self-medication[END_REF]. Self-medication does not necessarily imply pharmaceuticals, but, in the context of most contemporary health systems where the biomedical model has established itself over other popular and traditional medicines, the meaning of self-medication is usually more limited and refers to pharmaceutical drugs and to the absence of control by certified biomedical professionals on their use. Thus, self-medication is based on the principle that some pharmaceuticals can be sold without a prescription, when consumers can use them safely and effectively by following the medicine's instructions and/or seeking advice from a pharmacist. Self-medication with pharmaceuticals is a growing phenomenon on an international scale [START_REF] Baxerres | Du médicament informel au médicament libéralisé : une anthropologie du médicament pharmaceutique au Bénin[END_REF]. While in some legal contexts, self-medication can only be practiced using medicines purchased in the presence of a pharmacist (Cambodia, France), in others, the role of the pharmacist has been eroded and OTC (over-the-counter) medicines are freely accessible (Ghana, United Kingdom, United States). Public health actors increasingly cite the ideology of democracy in health [START_REF] Bureau | Les patients contemporains face à la démocratie sanitaire, Introduction au numéro thématique sur le « patient contemporain[END_REF] to justify policies that incentivize self-medication, by promoting individuals' responsibility in managing their health including through the use of pharmaceuticals. Moreover, policies to incentivize self-medication are also economically pragmatic, limiting clinical consultations and so reducing costs to states in covering medical expenses [START_REF] Ruiz | Risks of self-medication practices[END_REF].

Social science researchers have highlighted the limitations of these normative definitions by emphasizing the complexity of self-medication practices. Sylvie Fainzang shows that the inherent autonomy of these definitions is not limited to accepting or refusing to submit to biomedical professionals: "It implies that individuals must decide for themselves on a treatment based on their personal history, the information they have about their condition and what they identify as symptoms, and their perceptions about how health professionals treated their conditions in the past" (2012: 9). Furthermore, patients practice "disguised selfmedication" when they suggest that their doctors prescribe them certain products during a consultation that they will consume themselves or give to a family member (2012:3). For others, "there is only a thin line between self-medication and prescribed medication, and a doctor or nurse can never be sure a patient will take medicines exactly as they were instructed" (Van der Geest, Whyte and Hardon 1996: 165). Conversely, individuals may follow the advice of informal actors who are not authorized to prescribe and who may or may not be biomedical professionals [START_REF] Jaffré | La construction sociale des maladies, les entités nosologiques populaires en Afrique de l'Ouest[END_REF], but this may also be considered as adhering to a prescription. Self-medication and adherence to prescribed medication are not always mutually exclusive in practice.

Here, we have limited our investigation of self-medication to the use of pharmaceuticals. We consider these practices to be a product of a specific pharmaceutical system rooted in the specific history of pharmaceutical circulation in Cambodia. In our analysis, we consider this interconnection between self-medication, the social history of medicine, and the pharmaceutical system. By "pharmaceutical system," we allude to the modes of pharmaceutical procurement and distribution established by a state to ensure the availability of necessary medicines for population health in the country (Desclaux cited in Baxerres 2013: 31) and other less formal regulatory modes [START_REF] Quet | Regulation multiple: Pharmaceutical trajectories and modes of control in the ASEAN[END_REF] of procurement and distribution. The Cambodian health system, weakened by many years of political instability (particularly 1970-1991), has been slowly rebuilding. Despite economic growth and rising health indicators, improving health services remains a major objective. Social protection schemes, such as the Health Equity Fund, allow for free medical access to the poor in the public sector, but coverage remains relatively low [START_REF] Jacobs | Community participation in externally funded health projects: lessons from Cambodia[END_REF]. Although overthe-counter drugs have been covered by legislation since 2009, the practice of self-medication with pharmaceuticals is widespread, resulting in drug resistance to antibiotics and antimalarials [START_REF] Om | Cambodia: the first national study of antibiotic prescribing and resistance using mixed methods approach[END_REF]. Further, contrary to the law, people can buy virtually any type of medicine without a prescription from retailers, making self-medication a major concern for public officials and research scientists. The principles of democracy in health are neither a priority nor the watchwords of national public health policies, except for certain global health issues (AIDS, tuberculosis) where patient autonomy is emphasized in confined spaces of care [START_REF] Bureau-Point | The structural violence of patient participation in Cambodian HIV services[END_REF].

Based on ethnographic research of the pharmaceutical system in Cambodia, conducted in one urban and one rural area between January 2015 and June 2016, we analyse the complex dynamics surrounding self-medication, highlighting the legacy of history and the logics of distribution and consumption where individuals bear the burden of covering their health expenses.

METHODS

The study on which we draw is part of the Globalmed program 1 that is investigating pharmaceutical systems in three countries of the global South (Benin, Cambodia, and Ghana).

This study was conducted in Phnom Penh, Cambodia's center of business and government and a transit hub for most medicines used in the country, and in a district in Battambang province, northwestern Cambodia. We spent one and a half years in the field to familiarize ourselves with key actors, gain the trust of some distributors, and gradually obtain the relevant information, using several qualitative and quantitative methods. Semi-directed interviews were conducted with 24 mothers from a broad range of socioeconomic backgrounds (three living on <US $100 per month, ten on US $100-400 per month, eight on US $400-2000 per month, and three on >US $2000 per month) to obtain information about them and other family members (spouse, children, others). Among the 24 mothers, 13 were from Phnom Penh and 11 from Battambang. The study targeted mothers because of the gendered role of women as caregivers.

In Phnom Penh, the mothers' average age was 33 years, in Battambang 26 years. In Phnom Penh, their professional status was wide-ranging (teacher, actor, daycare worker, caretaker, job seeker, non-governmental organization employee, stay-at-home mother, market-stall vendor), while in Battambang, women were primarily farmers, with a few civil servants and merchants. All families were Buddhist, except for two in Phnom Penh (one Muslim and one Protestant). Interviews with the mothers addressed the following topics: usual place for purchasing medicines, types of care sought (traditional, neo-traditional, popular and biomedical medicine), 2 commonly used medicines in the family, and perceptions of diseases and health. We monitored these families' medicine consumption every two weeks for an average period of three and a half months. "Medicine" was defined broadly to mean any product consumed or used for health. We asked mothers to carefully memorize the various medicines used by family members and, when possible, to keep the labels. For each medicine consumed, we filled out a "medicine sheet" including the name of the medicine, its packaging, price, and source, where it was purchased, the person who recommended or prescribed the medicine, the person who used it, and the duration and reasons for treatment.

Interviews were also conducted with 57 people involved in the regulation and distribution of drugs: retailers in pharmacies and pharmacy depots, proprietors of medical practices (doctor, nurse, midwife), semi-wholesalers, 3 health center staff, informal vendors working in unregistered pharmacies, small grocery shops, or directly in the street, medical sales representatives, representatives from state agencies, and representatives from "pharmaceutical companies." 4 These interviews addressed: professional training, medicine distribution, source of medicines, laws governing the pharmaceutical system, and inconsistencies between laws and practices. We collected information about the sites where medicines are sold including their history, organization, operations, and the type of medicines distributed. We also observed onsite interactions between vendors and buyers in private outlets such as pharmacies, depots, and "houses that sell medicines," as explained below); this included 270 purchases in Phnom Penh and 121 in Battambang. We noted how patients access medicines (asking directly using the product's scientific, trade, or popular name; specifying symptoms/illness/organ; or presenting a prescription), and collected information about the products and the vendor (quantity/price/vendor profile). In general, accessing information about medicine distributors and vendors was challenging, given the sensitive nature of medical supply and distribution in Cambodia (Bourdier, Man and Res 2014). 5

HISTORY OF PHARMACEUTICALS IN CAMBODIA

The pharmaceuticalization 6 of Cambodian society started when the first pharmaceuticals were introduced during the French protectorate , supplementing other medicines in circulation particular to various medical paradigms (Theravada Buddhism, Ayurveda, Chinese medicine, and animist theories). Beginning in 1923, pharmacy health officials, also referred to as "pharmacists from Indochina," were trained at the Hanoi Faculty of Medicine in a fouryear program, and in Phnom Penh, four pharmacies were run by French pharmacists [START_REF] Neou | Contribution à l'étude de l'évolution du système pharmaceutique au Cambodge[END_REF]. This era saw dynamic pharmaceutical manufacturing, with over 400 trademark drugs produced in Cambodia between 1940and 1945(Bonnemain 2008). After independence (1955), under King Norodom Sihanouk, health officers in pharmacy were trained at the Royal College of Medicine of Cambodia, and the first graduates became pharmacists after completing a five-year program in 1962. Since this period, pharmacists have mainly worked in Phnom Penh in pharmacies, while health officers have run depots in the provinces.

Cambodians only purchased medicines after consulting their doctors, who had issued a prescription [START_REF] Neou | Contribution à l'étude de l'évolution du système pharmaceutique au Cambodge[END_REF]). In the 1970s, the political situation began to deteriorate, and the collateral effects of the Vietnam War and the Lon Nol coup d'état weakened the country.

Medicine prices rose [START_REF] Ovesen | Pharmacists and other drug-providers in Cambodia: identities and experiences[END_REF]. Next, the country fell under the Khmer Rouge (1975)(1976)(1977)(1978)(1979), a radical Maoist communist regime based on an ideology promoting the purification of the Khmer people and an agrarian utopia aimed at self-sufficiency.

Intellectuals and professionals, considered to be impure, were targeted first, and of the approximately 150 pharmacists trained from 1962, no more than 26 were alive in 1979 [START_REF] Neou | Contribution à l'étude de l'évolution du système pharmaceutique au Cambodge[END_REF]. The Khmer Rouge did not reject Western medicine on the whole; the priority was to limit dependence on the outside world and to produce drugs within the country [START_REF] Guillou | Cambodge: soigner dans les fracas de l'histoire[END_REF]. In this context, the Khmer Rouge appropriated inventories from pharmaceutical companies and pharmacies, imported a few drugs, and implemented small-scale local production of vaccines and penicillin. However, pharmaceuticals were reserved for cadres and armed combatants. The remaining population consumed "neo-traditional" medicines, produced locally in cooperatives located across the country [START_REF] Guillou | Cambodge: soigner dans les fracas de l'histoire[END_REF]). These medicines were called aarj tunsaï by the people who consumed them, Khmer for "rabbit droppings" because of their resemblance. The Vietnamese intervention in 1979, marking the beginning of the Republic of Kampuchea, put an end to the Khmer Rouge regime. The priority was to remedy the lack of human resources by implementing a rapid training system: four years of training for pharmacy assistants, as occurred in Vietnam for health officers during the colonial period. Access to care and medicines was officially limited to the public sector within this state socialism. However, the scarcity of medicines following the reign of the Khmer Rouge fostered an environment in which the informal sector 7 thrived, especially involving untrained vendors in and around urban and rural markets [START_REF] Ovesen | Pharmacists and other drug-providers in Cambodia: identities and experiences[END_REF]. This was the start of what Laragh Gollogly has called "pharmaceutical anarchy" (2002).

After the United Nations intervention in 1991 and a return to stability under the constitutional monarchy of the new Kingdom of Cambodia, hundreds of international organizations arrived. The country entered the market economy, and with this, the start of a long process of liberalization of the pharmaceutical system, characterized by an increase in the number of pharmaceutical companies (174 in 2010 to 308 in 2015 according to DDF), an increase in the number of local production compagnies (10 in 2010 to 14 in 2015 according to DDF), an increase in the volume of medicines in circulation (10 000 in 2010 to 12 000 in 2015 according to DDF), and the development of a public and private distribution system dominated by the private sector [START_REF] Neou | Contribution à l'étude de l'évolution du système pharmaceutique au Cambodge[END_REF]. In 2013, 80 percent of medicines circulated in the private sector [START_REF] Men | Safety of medicinal products in Cambodia: Assessment of the pharmacovigilance system and its performance[END_REF], this pattern continues to the present. The current pharmaceutical system bears traces of the French protectorate. The retail distribution system is based on French law; it grants a monopoly to the pharmacist, who must oversee drug importation, distribution and sales. The words "pharmacy" (pharmacie) or "depot" (dépôt), the official places for retail distribution discussed below, are still written in French on pharmacy storefronts (see Figure 1).

Insert Figure 1 about here Academic programs in pharmacy and medicine are based on the French system. Many students complete internships in France where they become familiar with the medicines used there that they will later prescribe or distribute in their day-to-day practice in Cambodia. For a long time most imported medicines came from France [START_REF] Ovesen | Pharmacists and other drug-providers in Cambodia: identities and experiences[END_REF]: 50 percent of distributed medicines came from France in 1994. In 2015, however, according to the Department of Drugs and Food (DDF), medicines now come from Asian countries: India (31%), Thailand (7%), Korea (6%), Vietnam (5%), other countries (35%), as well as France (7%) and produced in Cambodia (9%).

"French medicines" (thnam barang, thnam: medicine, barang: French) still appear to have the best reputation, and this category continues to carry weight in discourses. 8 However while its French characteristics are significant, the current pharmaceutical system has been shaped by a range of influences. Wholesale distribution in particular does not fulfill the standards in force in France nor other former French colonies, such as Francophone West Africa where pharmaceutical legislation aligns closely with that of France [START_REF] Baxerres | Du médicament informel au médicament libéralisé : une anthropologie du médicament pharmaceutique au Bénin[END_REF].

Wholesale distribution seems more liberalized in Cambodia, involving numerous pharmaceutical companies: 308 in 2015, versus seven in France and five in Benin [START_REF] Baxerres | Du médicament informel au médicament libéralisé : une anthropologie du médicament pharmaceutique au Bénin[END_REF]. Wholesale distribution in Cambodia most resembles the system in the Englishspeaking world, such as the United Kingdom, United States, and Anglophone West Africa, and the companies are not legally bound, as in France, to distribute all of the country's authorized medicines (interview, pharmacist, Phnom Penh, July 2015). Drug prices are regulated by the free market.

In the 1990s, the state began to regulate the drug market. Three specific licenses were established for resale distribution: the first to pharmacists; to compensate for the country's shortage of pharmacists, the second and third licenses are, respectively, issued to assistant pharmacists to open type-A depots and retired health professionals to open type-B depots.

Officially, the depots are authorized to sell a limited list of medicines; in practice, these limits are not taken into account. The national agency for pharmaceutical regulation-the current DDF-was created in 1994 and began to register medicines that same year. The first pharmaceutical law, still in force today, was introduced in 1996 and sets the general rules for manufacturing and distribution. Although law enforcement is a major challenge, since 2010, the government has intensified pressure on retailers to register with the Ministry of Health and apply for a license. With this, the number of places where informal sales take place has decreased considerably [START_REF] Men | Safety of medicinal products in Cambodia: Assessment of the pharmacovigilance system and its performance[END_REF]).

In the following section, we present the places people actually turn to when they want to purchase medicines. We will use self-medication in its public health meaning here to refer to the absence of any prescription from a health professional. In the last two sections, we focus more broadly on people's autonomy in medicine use, by discussing the interactions that develop between vendors and buyers in the various sites described.

SELF-MEDICATION IN DESIGNATED SITES FOR PHARMACEUTICAL DISTRIBUTION

Pharmacies and Depots

The majority of medicines taken by family members in the study were obtained in a pharmacy or pharmacy depot. This trend, already highlighted in the literature (CDHS 2015), may be for several reasons. Firstly, as noted above, the client 9 is able to obtain any medicine there without a prescription. Secondly, these sale points are widespread and so provide quick access. Vendors, including some health profesionals working in these sale points, are not familiar with the official list of OTC drugs and generally do not include them in their practices, with the exception of a small number of pharmacies in cities and tourist areas (Phnom Penh, Siem Reap, Sihanoukville and Kep) whose managers want to be known for applying best practice in pharmacy standards (presence of a pharmacist, air-conditioning, prescription medicines only sold with a prescription). At the time of this study, Phnom Penh had about 20 such pharmacies.

Many purchases in these sites fall under the narrow definition of self-medication.

Based on the Cambodian list of OTCs, most medicines purchased without a prescription in pharmacies and depots that we counted during our bi-monthly monitoring of families were prescription medicines (84% in Phnom Penh; 58% in Battambang). Beyond prescription medicines sold without a prescription, nearly all sales could be considered self-medication since according to the law, a pharmacist, assistant pharmacist or retired health professional must supervise OTC sales in pharmacies and depots. However, as elaborated below, we found numerous non professional drug vendors working in these outlets. 10 Further, in these sale points health profesionals often distributed medicines without consultation. In the rural study area, official drug distribution sites were temporarily given special status. These were neither pharmacies nor depots but "houses that sell medicines" (pteah louk osot 11 in Khmer).

According to a DDF representative and a provincial health representative (interviews, September 2015), this status was granted by the Provincial Health Department, at the time of regulatory efforts in 2010, to allow official private structures to open despite the lack of trained health professionals able to take responsibility in remote areas. The owners of these sites were mostly nurses from the community health center; in parallel to their roles in the public sector, these nurses dispensed medicines privately outside of their work hours, although they sometimes did this also during their public sector shift. During their absence, we noted that these private structures remained open, and that an unqualified person from their family network continued to conduct sales. This phenomenon, known as "double practice," has developed in the 1980s, and includes most health professionals in the public sector both in Phnom Penh and Battambang. In cities, the lack of pharmacists in pharmacies is due less to lack of human resources and instead to the lack appeal to pharmacists to work in pharmacies. Most pharmacists, according to our interviewees, seek jobs with international organizations or pharmaceutical companies that are much more rewarding financially and professionally. The pharmacists we met in Phnom Penh explained that they "lend" their licenses to representatives of pharmacies or pharmaceutical companies in exchange for US$100-150 per month. With certain discomfort, they explained that they rarely set foot on the premises for which they are officially responsible. "What use are all those years of pharmaceutical studies if it's just for a job earning between 150 and 300 US dollars per month that's usually performed by unqualified people?" remarked Sopheap, 12 a pharmacist, aged 32, in Phnom Penh. These "pharmacies without pharmacists" has been described by [START_REF] Ovesen | Pharmacists and other drug-providers in Cambodia: identities and experiences[END_REF].

Health Centers and Hospitals in the Public Sector

Most of our interviewees in were critical of referral hospital and health centers.

Waiting time to be seen is lengthy, and drug distribution in the public sector does not seem to meet patients' expectations. Various interviewees, from both urban and rural areas, claimed that "there's only para (paracetamol) at the health center," and "they don't have everything you need; there are frequent stockouts, and then we have to go buy medicines in the private sector." People with financial means generally avoid this sector or use it for specific reasons only: access to expensive medicines distributed for free (triple therapies for HIV or tuberculosis), reproductive health follow-up visits (contraceptives, vaccines for pregnant women or neonates), access to free treatment (for poor people with a fee-waiver card), or use of the ambulance transport system in an emergency. In these facilities, patients see a health professional before being sent to the in-house pharmacy with a prescription, and so access to medicines in this sector does not fall into the category of self-medication.

Private Clinics and Consultation Rooms

Private clinics are the responsibility of the Ministry of Health and are identified as having more than five hospital beds. According to our observations and interviews, medicines obtained in these facilities were prescribed by certified prescribers. Most clinics have either an in-house or an adjoining pharmacy, usually run by a family member of the owner, and there is a strong incentive for patients to buy their medicines from these facilities. Generally, our interviewees consider these places expensive because both the consultation with a professional and the medicines are subject to fees. Also, because they are located in urban areas, rural patients must cover transportation costs. Patients only consult them for serious problems, when they think access to a specialist and medical equipment is required.

Private consultation rooms are smaller than clinics and are the responsibility of municipal health departments. Many people use them, both in the city and countryside.

Medicine distribution practices are similar to those in pharmacies and depots, and at first glance, many sales seem to fall under self-medication. The doctors, nurses, midwives and dentists who work there, along with other non-qualified vendors who replace them during their absences or assist them during peak times, take on the role officially reserved for pharmacists and gear their activities toward selling medicines. Health officials maintain that private consultation rooms may carry outpatient drugs for patient care; however, in practice, they have an arsenal of medicines sometimes equal to those of pharmacies and depots.

Moreover, although they are not authorized to sell them, the opposite occurs: the staff at these facilities consider that while the consultation, which rarely takes place, is free, the medicine must be purchased. 13 This is a prime example of the commodification of medicines (Whyte, Van der Geest, and Hardon 2002). These professionals and laypersons distribute medicines as quickly as pharmacies and depots, with limited conversations with the patient, as the following excerpts illustrate (Table 1).

Insert Table 1 about here

Can it be said that these distribution methods are "prescriptions" even though, strictly speaking, the professionals do not consult with their patients? In situations where health professionals respond to a patient's spontaneous request without taking the time to check their health status or properly performing a clinical diagnostic exam, the distribution fits our definition of self-medication. Our definition also applies when medicine is distributed by a non-qualified member of the health professional's social/familial network.

Non-Governmental Organizations (NGOs)

People in poor areas of Phnom Penh sometimes have access to pharmaceuticals when doctors employed by NGOs visit and consult in these neighborhoods. The drugs are usually distributed free of charge. after a consultation with a doctor working for the organization.

Sometimes the doctor writes a prescription when the medicine is out of stock. Spontaneous requests for medicines also occur within this distribution method, resulting in self-medication practices. However, in the slum area of Phnom Penh where we conducted our study, the NGO medical staff came only once a week, creating a perception among residents that this point of care only provided limited assistance.

The Informal Sector

In both Phnom Penh and rural areas, the families that we monitored mainly purchased their medicines in registered locations. In our follow-up, the use of medicines in the informal sector was minimal (one percent of medicine purchases). Only a few purchases of paracetamol were made in small grocery shops (Figure 2).

Insert Figure 2 about here These purchases are another form of self-medication, in the narrow meaning of the term. Bypassing formal procedures, families may ask health professionals living nearby to make house calls, less for emergency reasons than for ease of access and confidentiality.

Generally, professionals sell drugs during these visits, as they do when approached with spontaneous requests for these medicines.

Practices at the various distribution sites in Cambodia illustrate the limitations of the normative definition of self-medication. Self-medication, though prevalent in pharmacies and depots, is also found at the prescriber level in private medical practices and through distribution by NGOs and in the informal sector. Therefore, it appears inappropriate to consider self-medication in Cambodia solely in official sitespharmacies and depotsthat are authorized to supervise this practice.

CLIENT PRACTICES: SELF-MEDICATION OR FOLLOWING A PRESCRIPTION

We now turn to observe practices from a less restrictive perspective, in which self-medication is considered an expression of individual autonomy. Generally, autonomy is ubiquitous in seeking care and manifests outside medical recommendations in response to a specific health system, history, and representations of health.

Drug Vendors

Drawing on interviews and observations, in private medical practices, pharmacies, and depots, clients believe they are dealing with qualified health professionals who possess the medical expertise and proper pharmaceutical knowledge to meet their needs. Clients rarely know the professional status of those who treat them and frequently call the people they meet at these various health care points pet (a diminutive of kru pet: kru, master; pet, hospital, translated in English by "doctor" but used to designate all health professionals). Health professionals often own depots or pharmacies, and the vendors working alongside them who sell medicines are generally from their social and familial environment (a spouse, niece or nephew, cousins, son or daughter, or family friend). Regardless of their family status, they are perceived as pet, based on their somewhat remote relationship to biomedical knowledge, as health professionals acknowledged: "When one family member is pet, the others become pet also." Consequently, in popular perceptions, retailers provide both professional health consultations and medicines, and a consultation that does not result in dispensing medicine is generally perceived as useless. People usually have one or two preferred locations where they purchase medicines, based on prior experiences. A trusting relationship is established with the people who work there, built less on the status of the location and professionals than on interpersonal relationships and the perceived efficacy of the treatment received.

Several factors explain why the status of the sites and professionals ultimately plays a minimal role in building trust. Firstly, we mentioned that people hardly distinguish between private medical practices, pharmacies and depots. The law has designated pharmacies and depots by green crosses and private clinics and consultation rooms by blue ones. However, in practice the colors do not always comply with these standards (Figure 3), and seldom serve as a reference point for individuals to distinguish between these distribution points. More generally, the coexistence of two color codes in popular perceptions in Cambodia-until recently, no distinction was made between green and blue-partially explains why these color-coded crosses are inefficient. 15 But patients in private consultation rooms and pharmacies feel that they are speaking to health professionals, and so this does not reflect a self-medication approach.

Insert Figure 3 about here

Interactions between buyers and vendors

While observing interactions between buyers and vendors (professional or not) in the various private sites, we noted that most purchases were made on the basis of explaining the symptoms, the name of the malady, or even mentioning an organ to the vendor, which they often associate with the term thnam. 16 Buyers also asked for a special type of formulation, as we will explain below. In Table 2 we provide a few "semiological descriptions" (Jaffré and Olivier de Sardan 1999) used for medicines in Cambodia, corresponding to the main ailments that individuals face day to day, indicate the type of formulations that clients value, and provide some examples of pharmaceutical content commonly used for these ailments.

Insert Table 2 about here

Except for a few widespread names such as para (paracetamol), amo (amoxicillin), ampi (ampicillin), P (Phosphalugel®) and calcium, most of ways that buyers asked for medicines help compensate for a lack of knowledge of drugs' scientific and trade names.

While monitoring medicine consumption by families, we found that spontaneously asking vendors for a medicine by its specific scientific or trade name occurred 44 percent of the time in Phnom Penh and 35 percent in Battambang. If self-medication is understood as a spontaneous request for a medicine from a vendor, then the rates appear to be lower than when using the normative definition of self-medication (purchase of a prescription medicine without a prescription). As noted, 84 percent of depot and pharmacy purchases in Phnom Penh and 58 percent in Battambang can be classified as cases of self-medication, but depending on how self-medication is defined, the rates can vary significantly. The Globalmed study conducted in Benin and Ghana using the same methodology shows the opposite: the vast majority of clients spontaneously request a medicine that they want to purchase (65-80 percent in numerous sites that conduct retail distribution of pharmaceuticals in the two countries). For various reasons explained below, vendors in Cambodia maintain control of medicine sales.

Layperson Influence in Using Medicines

The consumer has influence on some aspects, such as treatment duration. One trend, not specific to Cambodia, is stopping treatment as soon as the patient feels better. Thus, the consumer frequently determines the treatment duration. At time of purchase, if clients do not specify the duration, many vendors (professional or not) ask them how long they want to take the medicine. Perceptions about health and the efficacy of medicines may explain this lay influence. Clients usually want to test the medicine on themselves before buying the full treatment. They buy enough for one or two days, explaining that they will return to get the remaining treatment if they feel an improvement. As illustrated by the concept of hiyang (compatible) in the Philippines (see Whyte, Van der Geest and Hardon 2002), emic perceptions suggest an interpretation of efficacy that differs from that of biomedicine.

Although biomedicine widely assumes the universality of treatments, recurring emic perceptions worldwide suggest a different interpretation of efficacy. In Cambodia, according to [START_REF] Res | Social and cultural complexitiesof anti-malarial drug circulation: an ethnographic investigation in three rural remote communes of Cambodia[END_REF], the concept of korp (fit) illustrates these same emic perceptions. Economic reasons further explain why treatment duration is set by laypersons. Clients frequently show a specific amount of money in their hand, and vendors suggest a treatment based on this amount. In this case, the context is one of forced autonomy, whereby patients make decisions based on their capacity to pay. Moreover, most individual vendors respect clients' wishes to win their loyalty and not risk losing them to a competitor. However, vendors can and do influence consumer autonomy in other ways, as we explore below.

Sales Strategies and Knowledge Acquisition

Medicines as tablets or blister packs are rarely sold in their original packaging, but more often are sold in bulk in clear plastic bags sealed with a rubber band and containing several doses. This mode of formulation is not specific to non-professional vendors but is also practiced by health profesionals. In Khmer, these bags are called thnam psoam, literally "mixed medicines" and nicknamed "cocktails" in Cambodia both by researchers [START_REF] Gryseels | Injections, cocktails and diviners: therapeutic flexibility in the context of malaria elimination and drug resistance in Northeast Cambodia[END_REF][START_REF] Yeung | Quality of antimalarials at the epicenter of antimalarial drug resistance[END_REF] and in the media [START_REF] Sassoon | Cautious optimism as malaria drug cocktail makes a comeback[END_REF]). During our study, a few interlocutors told us that this practice directly derived from the practice of kru khmaer, which generally mixes different phytotherapeutic products. Public health officers criticize this because of the risks of overdosing and drug resistance. Frequently, vendors put two types of antibiotics, analgesics or anti-inflammatories in one bag. This phenomenon is also widespread in Laos (Newton et al. 2008); in Thailand, it has gradually diminished and disappeared (pers.comm., Supang Chantanavich, 2015). In Ghana, some "mixtures" appear similar to thnam psoam and were more common before.

In Cambodia, one bag usually corresponds to one dose (Figure 4). Rarely do vendors provide a single type of medicine per bag; rather the bags usually include three to eight different medicines, combining bulk tablets with blister tablets, whose quantity, price and colors vary depending on the vendor, client, urban or rural context, and health issue. Some vendors are reputed to compose thnam psoam with many medicines; others limit them to three or four. The thnam psoam have the distinction of being multi-colored, and retailers suggested that "adding some color" was important when preparing an "appealing thnam psoam." For example, red vitamin tablets had the double advantage of adding color and increasing the number of medicines without causing undue harm.

Insert Figure 4 about here For vendors, the preparation of the thnam psoam allows them to unload the least expensive medicines (usually from Cambodia and India), although at times, especially in cities, clients request thnam psoam with "French medicines," which may increase the price eightfold. It also allows vendors to meet their clients' demands, a key point in any business activity. Generally, vendors have repeat customers and know their preferences, and try to guess the preferences of passing clients based on their appearance (deducing purchasing power through clothing) and their comments. Interactions between vendors and buyers are brief, and vendors manage with little direction from the patient to guide the treatment. From the vendor's viewpoint, one advantage of the thnam psoam is reducing the number of explanations; if the components were given separately, the vendor would have to explain each one to the consumer.

The thnam psoam are requested and/or sold for certain categories of health problems, such as pdassaï, 14 toothache, stomach ache and diarrhea. Some retailers prepare bags in advance for these different pathologies, but arrange their displays so that they are not very visible from outside the point of sale. They fear inspectors' visits or being reported by potential competitors, regulators of best pharmacy practices, even researchers. Those who prepare the thnam psoam in advance usually sell in large quantities, for example, they make bulk sales to small dealers who redistribute them informally in the dynamic working-class neighborhoods of Phnom Penh where textile factories are located, for example, or in small shops in rural areas. The bags are usually prepared "on demand" in pharmacies, depots and private medical practices. Except for the very few retailers who distance themselves from these practices, denouncing them and explaining the disadvantages of thnam psoam to their clients, all retailers we met prepare them. Some argue that if they stopped, they would lose their clientele due to patients' high demand, explained below.

The thnam psoam are mainly composed of bulk medicines from boxes of 50 to 100 tablets with fairly uniform packaging (usually generics) placed under the counter (Figure 5).

According to vendors, this prevents clients from identifying the packaging, therefore gaining their loyalty by guaranteeing that they will return if they like the treatment provided. Further, vendors frequently swap boxed medicines into other boxes or containers so that clients cannot identify them by name or appearance. One vendor, for example, explained to us how she arranges her drugs: "All of the most commonly used medicines are in bulk. I take them out and put them in the other boxes. It's a question of keeping clients, and beyond that, it's more convenient for making the thnam psoam" (Phnom Penh, April 2015).

Insert Figure 5 about here For many consumers, the thnam psoam guarantees an effective treatment. Different explanations emerged from our study. "It's more effective to take the thnam psoam than one single medicine because when you're sick, there's always several health problems. So, there must be one medicine for each problem" (mother, Phnom Penh, February 2015). Local perceptions of efficacy sometimes dictate that the number of medicines should be proportional to the number of symptoms. For example, someone who has a headache, sore throat and fatigue will expect three different kinds of medicines. For others, consuming several medicines at the same time "helps you get better faster" (father, Battambang, March 2016). Moreover, although the price of thnam psoam can vary widely (US $0.25-$3.00), on the whole, it allows people to get several pills at an affordable price. In addition, consumer does not need to remember the dosage for each medicine, just the daily number of bags recommended by the vendor.

Although this distribution method may facilitate adherence, the consumer has no idea of the products being consumed. Furthermore, once the bags of thnam psoam are prepared, the patient has no way of knowing the contraindications or checking expiration dates. The speed of the exchanges also limits access to information. From our point of view, the distinction lies in the potential for individual empowerment, in the sense of access to knowledge about medicines, i.e., their names and their indications (expected effects). Thus, selling medicines through thnam psoam prevents individual empowerment and keeps consumers dependent on their vendor.

CONCLUSION

In this study, we revisit the definition of self-medication put forward by public health policies.

From our point of view, self-medicationmedicines purchased and used without a prior medical consultationdoes not encompass the boundaries of the phenomenon where the biomedical standards of drug prescription and distribution are not applied. The public health definition places disproportionate responsibility on patients for their health, and minimizes the role of health professionals, institutional representatives and structural context.

In this article, we took an approach based on individual autonomy, and considered the history and the current dynamics of drug circulation in a specific pharmaceutical system, so revealing the many meanings of self-medication. We consider that self-medication should be understood as both relational (i.e., undertaken in interactions with others who are seen as having medical knowledge and are in a position to provide medicines) and as pragmatic, in weak health systems where insurance coverage is low and people are poor. Clients and vendors find a "match" in which the autonomy of both the client and the seller are negotiated.

The consequence of the pharmaceuticalization of Cambodian society and the weight of history is that at the time of our study, many medicines are purchased without a prior medical consultation. The biomedical health system faces various challenges and where individuals bear the burden of covering their health expenses, and in this context drug distribution and specifically self-medication primarily take place in the private sector. Consumers are largely unfamiliar with the scientific and trade names of drugs, and drug vendors (professional or not) play a key role in controlling distribution through strategies that limit clients' ability to gain knowledge about medicines. Certain uses linked to popular perceptions about health and drugs certainly generate health risks (for example, deciding on the treatment duration).

As elsewhere [START_REF] Baxerres | Du médicament informel au médicament libéralisé : une anthropologie du médicament pharmaceutique au Bénin[END_REF][START_REF] Craig | Familiar Medicine: Everyday Health Knowledge and Practice in Today's Vietnam[END_REF][START_REF] Granado | The moment of sale: Treating malaria in Abidjan, Côte d'Ivoire[END_REF], this popular knowledge is constructed in a syncretic way based on the transmission of traditional knowledge, experiences in health care facilities and exchanges with health professionals, and actors involved in pharmaceutical distribution. In Cambodia, the harsh political regimes that held power, particularly the Khmer Rouge, influenced the process for acquiring popular knowledge about pharmaceuticals and during this period, few people had access to pharmaceuticals. In 1979, there were only 26 pharmacists left, official production and distribution sites were destroyed. The disruptive effects on people's personal relationship to medicines has endured a "depharmaceuticalization" of Cambodian society during this period.

In Cambodia, medicines remain primarily under the control of health professionals, but professional distributors are increasingly taking over that control. This has not resulted in a more rational use of products since most professional distributors, as we have seen, use pharmaceuticals as a lucrative "object" to revive economic activity, even if straying from the rules of medical practice. Thus, in contrast to the pharmaceuticalization process reflecting the increasing autonomous use of medicines [START_REF] Egrot | Anthropologie du médicament au Sud: la pharmaceuticalisation à ses marges[END_REF], in Cambodia the marketorientation of the provision of pharmaceuticals has left individuals with minimal control of their own health. Notes 1. For further information see http://globalmed.ird.fr/la-recherche/contexte-et-objectifs 2. Although we focus on pharmaceuticals in this article, in the study we examined the range of health practices people use: traditional medicine (Khmer medicine founded in the scholarly tradition transmitted through texts, primarily based on using medicinal plants and officially recognized by the Ministry of Health); popular medicine, meaning syncretic home remedies based on a combination of lay knowledge, knowledge of Khmer medicine and/or biomedicine; and "neo-traditional medicine," which uses products, often phytotherapy, from a variety of therapeutic traditions, with standardized, specific contents and packaging.

3. Semi-wholesalers purchase their supplies from "pharmaceutical companies," sell wholesale or retail, and have a pharmacy license. They are not authorized to import, yet our interviews indicate they do so illegally, mostly from neighboring countries such as Vietnam and Thailand. Sometimes these semi-wholesalers run an import company alongside their pharmacy.

4. In local use, the term "pharmaceutical company" refers both to local medicine manufacturing firms and medicine import-export and distribution companies. They have a special license from the Ministry of Health to import and export medicines.

5. The drug market is related to health but is also a lucrative market. Different actors along the biomedical medicine circulation chain use them as a resource to enhance their personal income. Biomedical standards are not always respected, and actors try to keep their practices secret so that ordinary citizens are unable to discern that they are evading the law.

6. This concept, analysed by [START_REF] Egrot | Anthropologie du médicament au Sud: la pharmaceuticalisation à ses marges[END_REF], refers to the increase in the volume of pharmaceuticals in circulation and their increasingly predominant place in society.

7. Pharmaceutical practices outside of frameworks are defined by the state and the country's health officials.

8. This category is subjective and is not strictly related to the source of medicines. Drugs considered to be in this category by both clients and vendors may come from France but also from Korea or Germany. Generally, these are expensive drugs, similar to the category "French drugs" or "pharmacy drugs" described for Benin [START_REF] Baxerres | Du médicament informel au médicament libéralisé : une anthropologie du médicament pharmaceutique au Bénin[END_REF]. 9. In private pharmacies and depots, most drug vendors called consumers neak ting (buyers) or client pniou. In this article we use the term "client" to refer to the consumers of these private outlets. In hospitals and health centers, health professionals called them neak tchum ngeu (patient). 11. There is no universally recognized phonetic transcription system in Cambodia; in this article, we used a liberal transcription system to facilitate the pronunciation of Khmer words for an English speaker. 12. To protect the subjects' privacy and confidentiality, pseudonyms are used throughout.

13. As explained by a member of DDF (Phnom Penh, August 2018), the Ministry of Health is in the process of solving this problem.

14. Pdassaï refers to a "nosologic popular entity" [START_REF] Jaffré | La construction sociale des maladies, les entités nosologiques populaires en Afrique de l'Ouest[END_REF] generally translated as "flu" and "common cold;" Cambodians use the word pdassaï for different disorders such as runny nose, headache, sore throat, cough, fever and sneezing.

15. According to several local sources, the color green did not exist for a long time. One health professional remarked that "traditionally, we say that the rice fields or the trees' leaves are blue" (Interview, Phnom Penh, March 2015).

16. Although the word thnam is commonly translated by "medicine," it is a generic term that covers a vast lexical field. "Hair dyes," "nail polish," "wax," "tobacco," "pesticides," "paint" and "poison," for example, are also referred to as thnam. According to Michel Antelme and Gerard Diffloth (linguists specializing in Mon-Khmer languages), the word thnam is derived from the Khmer word dam, from the verb "to boil." This term refers to a combination of various products that have been processed using various methods (boiling, drying, cooking, crushing and grinding) to produce a final product that may not only be used to heal or embellish, but also to kill or destroy.

ACKNOWLEDGMENTS

The project was approved by the National Ethics Committee for Research in Health of Cambodia (466,NECHR). We thank all those interviewed during this research project for the time they generously gave us. We also thank Maurice Cassier who led us to the

  10. Generally, one of the vendors in these retail places has completed three months of training, organized by the Provincial or Municipal Health Department of the Ministry of Health, but this does not replace the training received by health professionals authorized to distribute medicines.

EVE BUREAU-POINT is an anthropologist at the French National Center for Scientific Research (CNRS) in Marseille. She undertook her PhD and two periods as a post-

FUNDING This project received funding from the European Research Council under the European Union's Seventh Framework Programme (FP7/2007-2013)/ERC grant agreement no. 337372.

conceptualization of "depharmaceuticalisation" for the situation of Cambodia during discussions at an internal Globalmed project meeting in September 2016, held in Paris.