Dataset of chemical concentration levels in food from the second French total diet study

Information about the TDS2 data set

1. Description of the study

The TDSs are based on a standardized method and have been recommended by the World Health Organization (WHO) and the European Food Safety Authority (EFSA) for many years. They consist in collecting food products representative of the population's consumption, preparing these foods "as consumed" taking into account population’s common practices, combining them as composite/pooled samples, analyzing these samples, assessing the population's exposure to the targeted substances and finally assessing the risk for substances for which reference values exist. Within the framework of the 2nd French TDS (TDS2), nearly 20,000 food products were collected in about 30 cities throughout the French metropolitan territory and prepared to form 1,319 samples. These products corresponded to 212 types of food representing nearly 90% of the diet of adults and children in France.

Each sample was composed of 15 sub-samples of the same food (same label) and mass, allowing for the representation of different brands and taking into account consumer food preferences (product origin, varieties, brands, preparation methods, places of purchase, etc.). The sub-samples prepared "as consumed" were thus representative of the consumption of the food. With a few exceptions, all samples were replicated twice during the study to cover potential seasonal variability in composition or contamination. Different foods were also collected in different regions of France, to take account of potential regional differences in contamination. The More details about the study methodology are provided in the TDS2 reports:

• https://www.anses.fr/en/system/files/PASER2006sa0361Ra1EN.pdf
• https://www.anses.fr/en/system/files/PASER2006sa0361Ra2EN.pdf

2. Description of the data set

The dataset presents data at the food item level, i.e. seasonal sample values were averaged at the regional level, then regional sample values were averaged to represent the national level. The original regional dataset is available in French at the following URL https://www.data.gouv.fr/fr/datasets/r/06797551-c1ad-40c5-8527-b3515d28fecd.

The TDS2 data set includes 173 substances: trace elements, minerals, environmental pollutants, mycotoxins, neoformed compounds, additives and phytoestrogens. The analytical methods used for each family of substances and the analytical limits (LOD and LOQ ) are described in the study reports.

2.1. Pre-processing of concentration data

Three hypotheses for the management of left censored data (concentration value below the analytical limits) were applied for all substances:

• The lowerbound (LB) hypothesis: Concentrations below the LOD (undetected substances) were replaced by 0, and concentrations below the LOQ but above the LOD (known as "traces") were replaced by the LOD value;
• The middlebound (MB) hypothesis: Concentrations below the LOD were replaced by ½ LOD, and concentrations below the LOQ but above the LOD were replaced by ½ (LOD+LOQ) ;
• Upperbound (UB) hypothesis: Concentrations below the LOD have been replaced by the LOD value, and concentrations below the LOQ but above the LOD have been replaced by the LOQ.

In order to use the concentration value to assess exposures in relation to the available toxicological reference values, some data were processed. Thus, for mercury and arsenic, substances analysed in their total form, speciation assumptions were applied to the concentrations in order to estimate the organic and inorganic part in each sample (cf. study report, volume 1, p35). Similarly, for some compounds, sums were calculated. These are for example the sums of dioxins and furans, weighted by the toxic equivalency factors of 2005, or the sums of the 3 congeners of polybrominated biphenyls (PBBs). For these groups, data are available both for the substance details and for the sums of the three PBB congeners.

2.2. Thesaurus

he list below presents the variables in the data set and their definitions:

• family: name of the chemical group of the substance;
• subst: abbreviated name of the substance;
• subst_sn: short name of the substance;
• subst_cn: complete name of the substance;
• unit: unit of the mean concentration value of the substance;
• mean_CONTA_LB: mean of the concentration values of sub-samples of the analyzed food calculated under the lower bound hypothesis;
• mean_CONTA_MB: mean of the concentration values of sub-samples of the analyzed food calculated under the middle bound hypothesis;
• mean_CONTA_UB: mean of the concentration values of sub-samples of the analyzed food calculated under the upper bound hypothesis;
• Food_code: identification number of the analyzed food;
• Food_group: food category of the analyzed food;
• Type_foods: analyzed food.