A method to prioritize the surveillance of chemicals in food commodities to access international market and its application to four countries in Sub-Saharan Africa.

The purpose of this study was to propose an approach to predict the distribution of chemicals in food in developing countries to assess consumer risk and access to the international market with a limited number of laboratory analyses. The first step consists of identifying the GEMS/Food Contaminants database and the chemical/food combination relevant for a particular country. The identification of critical chemical/food combination should be used to prioritize the analysis to be performed in a total diet study (TDS). The second step consists of modelling a distribution model based on the mean concentration generated from TDS associated with the variability observed in a larger dataset consisting of individual food contamination data from the GEMS food database. The simulated distributions may provide information regarding how to establish food safety standards and to assess the potential for accessing international market in the context of a value chain. This method is illustrated by case studies from the recent Regional TDS (RTDS) conducted in Sub Saharan Africa. We concluded that further work is needed to gain experience and to fully validate this approach. However, organized data sharing and developing harmonized methods for data analysis are key roles for international organizations, such as FAO, WHO, and WTO. Finally, it is important to remember that such a data-driven approach still requires significant investments in terms of human resources and analytical capacity.

Identification of the main pesticide residue mixtures to which the French population is exposed.

Owing to the intensive use of pesticides and their potential persistence in the environment, various pesticide residues can be found in the diet. Consumers are therefore exposed to complex pesticide mixtures which may have combined adverse effects on human health. By modelling food exposure to multiple pesticides, this paper aims to determine the main mixtures to which the general population is exposed in France. Dietary exposure of 3337 individuals from the INCA2 French national consumption survey was assessed for 79 pesticide residues, based on results of the 2006 French food monitoring programmes. Individuals were divided into groups with similar patterns of co-exposure using the clustering ability of a Bayesian nonparametric model. In the 5 groups of individuals with the highest exposure, mixtures are formed by pairs of pesticides with correlations above 0.7. Seven mixtures of 2-6 pesticides each were characterised. We identified the commodities that contributed the most to exposure. Pesticide mixtures can either be components of a single plant protection product applied together on the same crop or be from separate products that are consumed together during a meal. Of the 25 pesticides forming the mixtures, two--DDT and Dieldrin--are known persistent organic pollutants. The approach developed is generic and can be applied to all types of substances found in the diet in order to characterise the mixtures that should be studied first because of their adverse effects on health.

The PERICLES research program: an integrated approach to characterize the combined effects of mixtures of pesticide residues to which the French population is exposed.

Due to the broad spectrum of pesticide usages, consumers are exposed to mixtures of residues, which may have combined effects on human health. The PERICLES research program aims to test the potential combined effects of pesticide mixtures, which are likely to occur through dietary exposure. The co-exposure of the French general population to 79 pesticide residues present in the diet was first assessed. A Bayesian nonparametric model was then applied to define the main mixtures to which the French general population is simultaneously and most heavily exposed. Seven mixtures made of two to six pesticides were identified from the exposure assessment. An in vitro approach was used for investigating the toxicological effects of these mixtures and their corresponding individual compounds, using a panel of cellular models, i.e. primary rat and human hepatocytes, liver, intestine, kidney, colon and brain human cell lines. A set of cell functions and corresponding end-points were monitored such as cytotoxicity, real-time cell impedance, genotoxicity, oxidative stress, apoptosis and PXR nuclear receptor transactivation. The mixtures were tested in equimolar concentrations. Among the seven mixtures, two appeared highly cytotoxic, five activated PXR and depending on the assay one or two were genotoxic. In some experiments, the mixture effect was quantitatively different from the effect expected from the addition concept. The PERICLES program shows that, for the most pesticides mixtures to which the French general population is exposed, the toxic effects observed on human cells cannot be easily predicted based on the toxic potential of each compound. Consequently, additional studies should be carried on in order to more accurately define the mixtures of chemicals to which the consumers are exposed, as well as to improve the investigation, prediction and monitoring of their potential human health effects.

Management options to reduce exposure to methyl mercury through the consumption of fish and fishery products by the French population.

This paper presents an updated assessment of exposure in France to methyl mercury through the consumption of fish and fishery products, and proposes several management scenarios which could reduce this exposure through changes to fish contamination levels or fish consumption patterns. The exposure model was applied in line with previous methodological results [Tressou, J., Crépet, A., Bertail, P., Feinberg, M.H., Leblanc J.Ch., 2004a. Probabilistic exposure assessment to food chemicals based on extreme value theory: application to heavy metals from fish and sea products. Food Chem. Toxicol. 42, 1349-1358; Tressou, J., Leblanc, J.Ch., Feinberg, M., Bertail, P., 2004b. Statistical methodology to evaluate food exposure to a contaminant and influence of sanitary limits: application to ochratoxin A. Regul. Toxicol. Pharmacol. 40, 252-263] so as to obtain a realistic estimate of probability and confidence intervals (95% CI) concerning French consumers exposed to levels exceeding the revised fixed provisional tolerable weekly intake (PTWI) for methyl mercury of 1.6 microg/week/kg of body weight, established by the Joint FAO/WHO Expert Committee on Food Additives in 2003. The results showed that young children aged between 3 and 6 years old or 7 and 10 years old, and women of childbearing age were at the risk groups. With respect to these groups and according to the fish consumers patterns (consumers of predatory fish only or consumers of predatory and nonpredatory fish), the results suggested that strategies to diminish MeHg exposure by reducing the amount of predatory fish consumed would be more efficient in significantly decreasing the probability of exceeding the PTWI than the implementation of international standards.

Statistical methodology to evaluate food exposure to a contaminant and influence of sanitary limits: application to Ochratoxin A.

This paper presents some statistical methodologies to evaluate the food exposure to a contaminant and quantify the outcome of a new maximum limit on a food item. Our application deals with Ochratoxin A (OTA). We focus on the quantitative evaluation of the distribution of exposure based on both consumption data and contamination data. One specific aspect of contamination data is left censorship due to the limits of detection. Three calculation procedures are proposed: [P1] a deterministic method using means of contamination; [P2] a probabilistic method using a parametric adjustment of the distributions of contamination taking into account the left censorship; and [P3] a non-parametric method which consists in randomly selecting the consumption data and the contamination values. Our main result shows that a non-parametric probabilistic approach is well adapted for the purpose of exposure assessment, when large samples are available. In the application to OTA, the probability to exceed a safe level is high, particularly for children. Simulations show that the impact of the existing standards on cereals and the currently proposed standards on wine generally do not significantly reduce the risk to be overexposed to OTA.

Probabilistic exposure assessment to food chemicals based on extreme value theory. Application to heavy metals from fish and sea products.

This paper presents new statistical methods in the field of exposure assessment. We focus on the estimation of the probability for the exposure to exceed a fixed safe level such as the provisional tolerable weekly intake (PTWI), when both consumption data and contamination data are independently available. Various calculations of exposure are proposed and compared. For many contaminants, PTWI belongs to the exposure tail distribution, which suggests the use of extreme value theory (EVT) to evaluate the risk. Our approach consists in modelling the exposure tail by a Pareto type distribution characterized by a Pareto index which may be seen as a measure of the risk of exceeding the PTWI. Using propositions by EVT specialists, we correct the bias of the usual Hill estimator to accurately estimate this risk index. We compare the results with an empirical plug-in method and show that the Pareto adjustment is relevant and efficient when exposure is low compared to the PTWI while the plug-in method should be used when exposure is higher. To illustrate our approach, we present some exposure assessment for heavy metals (lead, cadmium, mercury) via sea product consumption.

Nutritional intake of French soccer players at the clairefontaine training center.

Young, French male athletes undergoing intensive elite sports training at the National Training Centre in Clairefontaine served as the subjects (N = 180; age range: 13 to 16 years) in a 3-year dietary survey aimed at characterizing their nutritional intake in terms of energy, macronutrients, calcium, and iron. Each year, the subjects were grouped by level into 3 promotions so that 9 groups could be studied. Dietary intake data were collected each year for each subject in the 9 groups, using a 5-day food record. The results showed that their total energy intake (TEI) was insufficient for athletes (ranging from 2352 454 to 3395 396 kcal/d as opposed to the recommended range of between 3819 and 5185 kcal/d). Furthermore, their diet was unbalanced, with too great an emphasis upon fatty foods (29.1 2.8 to 34.1 3.1% TEI vs. the 20% recommended), to the detriment of carbohydrates (48.5 4.3 to 56.6 3.1% TEI vs. the 55 to 60% recommended). The calcium intake was too low in 5 of the 9 groups while, in contrast, the iron intake was satisfactory in all groups. Furthermore, during this 3-year period at the Clairefontaine Centre, the subjects significantly (p <.05) improved their calcium and iron intakes (1021 197 and 12 2 mg/d in 1996, 1299 155 and 16 2 mg/d in 1997, and 1252 184 and 17 2 mg/d in 1998). This rise in micronutrient intakes may have been due to a physiological adaptation to growth or to the positive effects of courses on nutrition given during their stay at the Centre.