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DIETARY EXPOSURE OF CHILDREN TO LEAD
Citation:
Melnyk, L J., M R. Berry Jr., L S. Sheldon, N. Freeman, AND E. D. Pellizzari. DIETARY EXPOSURE OF CHILDREN TO LEAD. Presented at American Chemical Society National Meeting, New Orleans, LA, August 22-26, 1999.
Impact/Purpose:
The overall objective of this research is to support NERL's human exposure measurement and exposure modeling efforts by reducing the amount of uncertainty in the dietary measurements critically needed for improved risk assessment. Specifically, the research provides the tools needed to collect and analyze food samples and to design and understand dietary measurements. The current specific objectives are:
1. to investigate more efficient methods for characterizing population exposures in dietary measurements studies (short-term subtask initiated in FY00; extramural);
2. to develop and improve analytical methods for contaminants in composite food samples collected in dietary measurements studies (long-term subtask; in-house);
3. to improve the model and food database system used in measurements studies for estimating dietary exposure and identifying sources (long-term subtask; extramural).
Description:
Children are the most susceptible population to lead exposure because 1) they have more opportunity for contact with lead sources due to their activities, 2) lead adsorption occurs more readily in a child as compared to an adult, and 3) the child's development is more vulnerable to lead than adults. Low levels of lead in the blood have been shown to cause adverse health effects: the level of concern for children is currently 10 ug/dL. The contribution of dietary exposure of lead to increased blood lead levels is not well characterized and is becoming a larger portion of exposure as others are decreasing (e.g., from leaded gasoline, lead in pain, lead solder in food cans, etc.). This study was conducted with experimental techniques to obtain estimated dietary lead intakes of children 2 to 3 years of age who live in homes contaminated with environmental lead. General research objectives were (1) to identify and quantify the sources of idetary lead exposure, (2) to estimate potential lead intakes for children consuming food in contaminated environments, and (3) to investigate potential correlations between daily exposure and measured blood levels of lead.
Dietary exposure was evaluated by collecting food samples that were representative of the foods the young children who participated in the study ate in their homes. A 24-hr. duplicate of all foods plus sentinel foods, i.e., individual food itmes used to represent foods for expsoure during handling, were collected from 48 children. Seven of the participants were revisited three times and three participants were revisited once to obtain information on the variation in dietary intakes. Drinking water was evaluated both as part of the beverage sample and by itself. Additional information collected included lead concentrations from hand wipes, floor wipes, and venous blood; and questionnaire responses on activities related to exposure.
All samples were analyzed by inductively coupled plasma mass spectrometry (ICP/MS) at Research Triangle Institute, NC. Measurements indicated that the activities and hygiene practices of children and their environment can influence the amount of lead ingested with food, which must be taken into consideration when detemining total dietary intake for the the defined subpopulation. Estimated dietary intakes of lead (37.5 ug Pb/day) were >4 times the measured 24-hr. duplicate-diet results (8.27 ug Pb/day), which were almost six times higher than the currently reported estimates from national survey (1.40 ug/day). Statistically significant correlations were established (p<0.05) between blood lead levels and hand wipes, blood levels and apples contacting contaminated surfaces, hand wipes and bananas contacting contaminated hands, and between drinking water and solid foods. This study indicates that the dietary route of exposure to lead is impacted by eating activities of children living in a lead contaminated environment and that excess dietary exposures are occurring.