TESTING DUPLICATE DIET SAMPLE COLLECTION METHODS FOR MEASURING PERSONAL DIETARY EXPOSURES TO CHEMICAL CONTAMINANTS

Dietary ingestion may be a significant pathway of human exposure to ma ny potentially toxic chemicals. The U.S. Environmental Protection Agen cy-National Human Exposure Laboratory has made the development of meth ods for measuring personal dietary exposures a high priority for its d ietary exposure research program. Of particular interest was the testi ng of methods that could be applied in the general population as one c omponent of multipathway exposure measurement studies. This paper desc ribes a controlled pilot study that was conducted to evaluate procedur es for collecting and processing duplicate diet samples. Nine adult an d three child participants volunteered to provide dietary information for 28 days, and duplicate portions of all foods consumed daily for se ven consecutive days. Sample collection procedures were evaluated for participant collection and segregation of solid and liquid foods, and for identification and separation of high-fat and low-fat foods. Metho ds for compositing and homogenizing mixed diet samples were tested Foo d records and questionnaires were tested to document the collected foo d and to evaluate procedures for assessing dietary changes and collect ion bias. Participant time and monetary needs were evaluated along wit h the approach for training and providing support to study participant s. Participants were able to collect 96% of the meals they consumed, e ven with 33% of the meals consumed away from home. Food consumed in so cial settings was the most difficult to collect, and participants were unable or unwilling to collect foods in some social settings. Noncoll ection of meals and food items increased after the third day of collec tion. Mixed diet samples were successfully homogenized, with 1%-11% me an relative standard deviations for moisture, fat, protein, and ash an alysis in replicate sample aliquots. The laboratory-measured caloric c ontent of collected foods was an average of 12% (range: -24% to 36%) l ower than estimates of energy intake using a food diary and 16% lower than estimated energy expenditure values.