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Discussions as to the extent of pesticide residue contamination in the food supply often rely on results of government residue monitoring programs focusing primarily upon the percentages of samples containing pesticide residues and the number of violative residues identified. Such an approach does not adequately convey the likelihood of pesticide residues posing consumer risks since residue regulatory limits are not safety standards and violative pesticide residues rarely constitute residues of health concern. It is more appropriate to develop estimates of actual dietary exposure to pesticides and to compare such estimates to established toxicological criteria such as the Chronic Reference Dose (RfD). The U.S. Food and Drug Administration’s (FDA) Total Diet Study (TDS) previously provided such information but last published its findings in 1995 to estimate dietary exposure to pesticides detected between 1986 and 1991. This paper provides updated estimates of dietary exposure to pesticides in the United States using the most recent TDS findings on pesticide residues. A total of 77 specific pesticides were detected from market basket samples of 2240 TDS food items analyzed by FDA in 2004 and 2005. All estimated exposures to the 77 pesticides for the General US population were well below chronic RfD levels. Only 3 of the 77 pesticides showed exposures greater than 1 % of chronic RfDs, while 14 showed exposures between 0.1 and 1 % of chronic RfDs and 19 had exposures between 0.01 and 0.1 % of chronic RfDs. The remaining 41 pesticides had exposures below 0.01 % of chronic RfDs. Compared with 1986–1991 findings, dietary exposure to six environmentally persistent chlorinated hydrocarbon insecticides were reduced by factors of 47 to 96 % in 2004–2005. Exposures to 15 different population subgroups were estimated and indicated that children, particularly two year-olds, frequently receive higher exposures to pesticide residues in their diets than do adults. Chronic dietary exposure to pesticides in the diet, according to results of the FDA’s 2004–2005 TDS, continue to be at levels far below those of health concern. Consumers should be encouraged to eat fruits, vegetables, and grains and should not fear the low levels of pesticide residues found in such foods.

Consumers are frequently exposed to arsenic in foods and considerable public and scientific concern exists regarding the potential health risks from dietary arsenic. Arsenic exists in both organic and inorganic forms and health effects are primarily attributed to inorganic forms. The most common analytical methods used to detect arsenic measure total arsenic, which includes both organic and inorganic forms. It is therefore necessary to make assumptions concerning the amounts of total arsenic found in food samples that represent inorganic arsenic. This work presents a new assessment of US dietary exposure to arsenic using data available from the FDA Total Diet Study from 2006-2008 and a series of scenarios developed to estimate inorganic arsenic levels. Total arsenic exposures were estimated for 16 population subgroups and ranged from 1.4 x10-1 to 4.5 x10-1 µg/kg/day. The population subgroup with the highest exposure to total arsenic was 2 year-old children. The major food group contributors to total arsenic exposure for the general US population were marine sources, which accounted for 69 percent of the total arsenic exposure, and grains, legumes and seeds, which accounted for 20 percent. The highest inorganic arsenic exposures occurred for 2 year-old children and ranged from to 1.1 x10-1 µg/kg/day to 2.4 x10-1 µg/kg/day. Inorganic arsenic exposures for the 2 year-olds were 3.3 to 4.8 times higher than inorganic arsenic exposures for the general population. Under Scenario 5, which assumed that 70 percent of total arsenic from terrestrial sources and 10 percent of total arsenic from marine sources existed as inorganic arsenic, the most important food group contributors to inorganic arsenic for 2 years-olds were grains, legumes and seeds (50 percent), beverages (14 percent), marine sources (13 percent) and snacks and breakfast cereals (12 percent). The exposures estimates obtained in this work are below the EPA’s established RfD of 0.3 µg/kg/day for inorganic arsenic and below EFSA’s health concern level of 0.3 to 8.0 µg/kg/day. To improve the accuracy of future arsenic risk assessments, studies should incorporate specific analytical data measuring inorganic arsenic from foods contributing the most to inorganic arsenic exposure.

Using trans-diphenylpropane oxide (tDPPO) as a substrate, we measured epoxide hydrolase (EH) activity in subcellular fractions of Alternaria alternata f. sp. lycopersici (Aal), a fungus that produces host-specific toxins. The activity was mainly (>99.5%) located in the soluble fraction (100,000 × g supernatant) with the optimum pH at 7.4. An increase of toxin production between days 3 and 9 found in a Aal liquid culture over a 15 days period was concomitant with a period of high EH activity. EH activity remained constant during the same period in an Alternaria alternata culture, a fungus which does not produce toxin. In vivo treatment of Aal culture with the peroxisome proliferator clofibrate stimulated EH activity by 83% and enhanced toxin production 6.3 fold. Both 4-fluorochalcone oxide (4-FCO) and (2S,3S)-(-)-3-(4-nitrophenyl)-glycidol (SS-NPG) inhibited EH activity in vitro with a IM50f 23 ± 1 μM and 72 ± 19 μM, respectively. The possible physiological substrate 9,10-epoxystearic acid was hydrolyzed more efficiently by Aal sEH than the model substrates trans- and cis-stilbene oxide (TSO and CSO) and trans- and cis-diphenylpropane oxide (tDPPO and cDPPO).