Exposure limiting dietary

Pesticide residues consist of chemicals that might occur in a commodity as a result of application of a pesticide. Such chemicals typically correspond to compounds for which a regulatory agency has or will set a tolerance, i.e., a maximum residue limit, specific to the commodity. In either a field study or a market basket survey, residues to be determined will be those which result from application of the specific pesticide that the study is intended to support. A market basket survey, however, might be intended to support not just one but several different pesticides of the same or different chemical classes. In addition, a market basket survey might include pesticides not used in the USA but for which import tolerances exist. For example, some uses of the parathion family of pesticides on food products have been abandoned in the USA but remain in other countries that export the products to the USA. A market basket survey offers a means to evaluate actual dietary exposures to residues of such pesticides. In addition, tolerance expressions frequently include multiple compounds, all of which must typically be determined in residue field trials. The sponsor of the market basket survey must decide whether to analyze for all compounds in the applicable tolerance expression or to restrict the program to selected analytes, such as the active ingredient. 

A chronic oral MRL was not derived because of the limitations of the available studies. Human studies that described dietary exposure to cyanide through consumption of cassava lacked quantitative exposure information. The one available chronic oral study in rats found no treatment related effects (Howard and Hanzel 1955). 

No clinical signs of neurotoxicity were noted in acute- and intermediate-duration dietary exposure studies using mice (Heindel et al. 1989 NTP 1985). Although these data are limited, it is not believed that the low-level exposure to di-w-octylphthalate that occurs at hazardous waste sites will result in neurotoxicity. 

Human Health At present, studies on the impact of POPs on human health are very limited in China. Most of the existing literature is focused on dietary studies, as the food chain is considered a major pathway for POPs to effect human health. Information on human health effects such as body burden and metabolism is insufficient and generally extrapolated from modeling data because few doctors have been involved in research on POPs exposures in China. Other exposures through respiration and skin as well as air and soil are seldom studied. 

In 2005, the EES A [62] made an estimation of PAE exposure in human populations based on the limited available literature on DEHP, DBP, BBP, DiNP, and DiDP concentration in foods and diets. Some studies have been conducted in two different populations in United Kingdom (UK) and Denmark from 1996 to 2003 [124—129]. Based on the information obtained from the mentioned studies, the EFSA estimated the daily oral intake and the maximum dietary exposure (calculated in the 95th percentile) (MDE) for the most used PAEs (Table 3). 

In the decision whether toxicity studies may be omitted at tonnage levels at or above 100 tons/year is appropriate or not, a TTC value might be used in the comparison with the available exposure information. However, due to limitations and uncertainties in the derivation of TTC values, as well as the fact that the TTC concept has not yet been evaluated for the diverse group of industrial chemicals and for different routes of exposure other than dietary, the Nordic group concluded that it is too premature to use the TTC concept within REACH. 

Exposure Levels in Environmental Media. Because of the paucity of data on the levels of thorium in air, water, and food, there are conflicting reports on the importance of each medium to the total human dietary intake of this substance. Data on the levels of thorium in foods grown in contaminated areas, particularly in the vicinity of hazardous waste sites, are limited, and further development of these data will be useful. There is also a lack of air monitoring data around hazardous waste sites. 

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