Daily food consumption values

Probabilistic approaches take advantage of current computational capabilities to combine all of the data in a pesticide residue distribution (rather than a single expected value) with food consumption data to develop a distribution of daily exposure. This approach is called a Monte Carlo simulation, although there are many ways to conduct this type of analysis. 

In the case of a single pesticide found on a single commodity, a Monte Carlo analysis would randomly select a residue data point and a food consumption level value and multiply them together to yield an exposure level. By repeating this process, often thousands or tens of thousands of times, it is possible to develop a distribution of daily exposures that would allow a determination of which levels represent, for example, the 50th, 99th, and 99.9th percentiles of consumption. 

The daily consumption figures used by tlie European Union, although similar to those proposed by JECFA, differ from the food factors employed in the United States. There is currently much debate over whether these daily consumption values represent a realistic food intake for the commodities involved. One could say that they neither take into account the so-called extreme consumer who... 

Toxic and essential trace elements intakes were computed from food consumption data of the population in northern Italy and element concentration measurements. The results (Table 10.6) were compared with the Italian Recommended Dietary Allowance (RDA) for essential trace elements and with the Provisional Tolerable Daily/Weekly Intake (PTDI/PTWI) for toxic elements. Finally, an assessment was made of the extent to which each food contributes to the total intake of trace elements by the population under study and the most contaminated foods were also detected. On the whole, mean intake values satisfied the Italian RDA for all the essential trace elements [31], while the potentially toxic trace elements were below the relevant threshold limits. 

Fig. 19. Effects of drug withdrawal after 10 days twice daily treatment with chlordiazepoxide (p.o.) on food consumption, body weight gain and rectal temperature in the rat. Note a decrease in food consumption and an increase in rectal temperature during the first 2 days after drug withdrawal with recovery towards vehicle control values thereafter. Similar but less marked effects are observed on body weight.

When calculating chronic dietary exposure, the deterministic models use point values for both food consumption and residue concentration, thereby yielding a point estimate of dietary exposure. In the US, the initial chronic dietary exposure estimate is the Theoretical Maximum Residue Contribution (TMRC) and is analogous to the Theoretical Maximum Daily Intake (TMDI) used to estimate chronic dietary exposure in the EU. Both the TMRC and the TMDI are relatively conservative estimates of dietary expostire. The TMRC is calculated as the product of the mean consumption value and the US pesticide tolerance [6]. In the EU, the TMDI is calculated as the product of the mean consumption value and the Maximum Residue Limit (MRL) [7]. The objective of both calculations is essentially identical to calculate an estimate of the central tendency of the dietary exposure. Both calculated values use the central tendency dietary exposure estimate as the estimate of chronic (long-term) dietary exposure and calculate it using mean consumption data and the maximum residue permitted on the commodity. 

The CLEA Guideline Values for non-carcinogens consider exposure from other sources of contaminants. Background exposure from non-soil sources, as defined in the mean daily intake (MDI), includes exposure through drinking water, food consumption and inhalation of ambient air. The MDI is subtracted from the TDI. Exposure to contaminated soil from other sources, such as that which may be tracked back to the house, is taken into account. This is done by allocating such exposure a percentage of (TDI — MDI), usually 50%, to the soil allocation factor (SAF). 

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