Lu et al. They also participated in a 5-day organic diet intervention in summer and fall seasons for CPES-WA children and summer and win- ter seasons for CPES-GA children in which organic groceries were provided to replace foods (mostly fresh fruits, vegetables, grains, and fruit juices) that their child usually ate (Lu et al. 2006a, 2006b). In additional to the 24-hr duplicate food samples (described below), two spot urine samples and dietary consump- tion information were collected daily from all CPES children. The University of Washington Human Subject Division (no. 03-5899) and Emory University Internal Review Board (no. 084-2005) approved the use of human subjects in this study and continued data analysis. No. of samplesa 16 Frequency of consumption (%)b 14.5 Food item CPES-WA Orange juice Blueberries Watermelon Applec Peachc Lemonade Grapec Corn Banana Apple juice Carrotsc Lettucec Broccoli Apple sauce Strawberriesc Raspberries Peas Potato Pineapple Nectarinec Mushrooms Honeydew Grape juice Cherriesc Spinachc Onion Mango Green pepperc Green beans Grapefruit Fruit punch Celeryc Cauliflower Cantaloupe Asian pear 8 7 7 6 6 6 6 6 6 5 4 4 4 3 3 2 2 2 2 2 2 2 2 1 1 1 1 1 1 1 1 1 1 1 Food sample collection and process. In both CPES studies, 1 day’s worth of 24-hr dupli- cate food samples were collected by parents and children on a study day selected at their conve- nience on which the child-participant consumed nonorganic foods in the summer and fall sea- sons for CPES-WA children, and summer and winter for CPES-GA children. Families were instructed to provide nonorganic samples of all fruits, vegetables, and fruit juices that were equal to the quantity consumed by the child, simi- larly prewashed/prepared, and obtained from the same source or batch (i.e., if the child ate half an apple, the parents submitted the other half of the apple, or if the child ate the whole apple, the parent submitted a second apple from No. of samplesa Frequency of consumption (%)b Food item CPES-GA Banana Strawberriesc Applec Orange juice Peanut butter Tomato Watermelon Pearc Carrotsc Apple juicec Spinachc Peachc Onion Mushrooms Lettucec Grape juice Broccoli Peas Olives Lemonade Grapec Fruit punch Corn Blueberries Apple sauce Potato Raspberries Plum Mango Green pepperc Green beans Celeryc Cantaloupe Cabbage 14 13 10 9 7 6 5 5 5 5 3 3 3 3 3 3 3 2 2 2 2 2 2 2 2 2 1 1 1 1 1 1 1 1 10.9 10.1 7.8 7.0 5.4 4.7 3.9 3.9 3.9 3.9 2.3 2.3 2.3 2.3 2.3 2.3 2.3 1.6 1.6 1.6 1.6 1.6 1.6 1.6 1.6 1.6 0.8 0.8 0.8 0.8 0.8 0.8 0.8 0.8 Table 1. The consumption of fresh produce and fruit juices by CPES-WA and CPES-GA children. 7.3 6.4 6.4 5.5 5.5 5.5 5.5 5.5 5.5 4.5 3.6 3.6 3.6 2.7 2.7 1.8 1.8 1.8 1.8 1.8 1.8 1.8 1.8 0.9 0.9 0.9 0.9 0.9 0.9 0.9 0.9 0.9 0.9 0.9 the same batch/bag of apples). Individual food items were collected using zip-lock bags, labeled, and stored in families’ refrigerators until picked up by the research staff the next day. Upon returning to the lab, individual food samples were weighed, homogenized, transferred to a condiment cup, and then frozen at –20°C until analysis at the Food and Drug Administration’s (FDA) laboratories. To ensure sufficient quan- tity for analytical analysis, food samples had to weigh at least 50 g. Individual food samples that weighed < 50 g were combined and processed as composite samples with other food items from the same meal. If a composite sample from a single meal weighed < 50 g, it was combined with food items from one or more additional meals to achieve a combined weight ≥ 50 g. We collected and analyzed 3 days’ worth of 24-hr duplicate food samples from CPES-WA chil- dren (two from summer and one from fall) and 2 days’ worth of 24-hr duplicate food samples from CPES-GA children (one each from sum- mer and winter). We also conducted a market basket analysis (MBA) to quantify organophosphate (OP) and pyrethroid insecticide residues in food items that CPES-WA children commonly consumed (based on daily dietary consumption informa- tion). We purchased 40 fresh fruit and veg- etable items from one of the two neighborhood supermarkets where CPES-WA was taking place. The MBA food samples were processed identically and analyzed in the same FDA labs as the 24-hr duplicate samples. We did not conduct an MBA for CPES-GA children because of a lack of research resources. Chemical analysis. Homogenized food samples were extracted using a modified QuEChERS (quick, easy, cheap, effective, rug- ged, and safe) method (Schenck et al. 2009) originally developed for rapid multiresidue determination of OP insecticides in fresh fruits and vegetables at the 1-ng/g level (Anastassiades et al. 2003; Podhorniak et al. 2001; Wong et al. 2007). Briefly, this method entails salt- out acetonitrile extraction of food samples with magnesium sulfate and sodium chloride, fol- lowed by a solid-phase dispersive cleanup using graphitized carbon black and primary secondary amine solid-phase extraction sorbents and the addition of toluene. Extracts were evaporated almost to dryness under a nitrogen stream at 50°C and reconstituted in toluene for determi- nation of OP and pyrethroid pesticide residues. The OP residues were determined using a gas chromatographic method with pulsed flame photometric detection, flame photometric detection, and mass spectrometry with limits of detection (LODs) ranging from < 1.0 to 10 ng/mL. The pyrethroid insecticide residues were determined using a gas chromatography method with halogen-specific detectors and/or mass spectrometric detectors, with LODs rang- ing from 5.0 to 25 ng/mL (Wong et al. 2010). aConsumption information was recorded from the days when 24-hr duplicate food samples were collected, and number of samples for each food item was summed among all children in each study. bCPES-WA consumption frequency was calculated based on a total of 110 food samples (some of the samples were composited samples). CPES-GA consump- tion frequency was calculated based on a total of 129 food samples (some of the samples were composite samples). cOne of the 12 most pesticide-contaminated fruits and vegetables surveyed in 2008–2009 (EWG 2009). Table 2. The frequency of pesticide residue detection in CPES 24-hr duplicate food samples. Total food No. of samples with No. of food samples contaminated (%) samples pesticide residue Study collected detected (%) ≥ 1 OP > 1 pesticide > 2 pesticides CPES-WA 110 25 (22.7) 23 (21) 3 (3) 9 (8) 3 (3) CPES-GA 129 19 (14.7) 10 (8) 7 (5) 1 ( < 1) MBA 40 11 (27.5) 9 (23) 2 (5) 1 (3) 0 (0) ≥ 1 pyrethroid 11 (9) 1626 ovlume 118 | number 11 | November 2010 • Environmental Health Perspectives