EVALUATION OF A FOOD FREQUENCY QUESTIONNAIRE FOOD COMPOSITION APPROACH FOR ESTIMATING DIETARY-INTAKE OF INORGANIC ARSENIC AND METHYLMERCURY

Inorganic arsenic intake in 969 men and women and methylmercury intake in 785 men and women from across the United States were assessed by a semiquantitative food frequency questionnaire, in combination with a database for the content of those elements in foods, and by toenail co ncentrations of arsenic and mercury, In addition, empirical weights fo r foods on the dietary questionnaire were derived from multivariate re gression models to estimate associations between diet and toenail arse nic and mercury levels, independent of the assumptions about inorganic arsenic and methylmercury in foods, which are based upon limited resi due measurements, The use of empirical weights significantly improved the correlation of arsenic consumption with toenail arsenic levels (r = 0.33, P = 0.0001), compared with the weak correlation obtained using the food residue method to calculate intake (r = 0.15, P = 0.0001), M ercury consumption computed using empirical weights yielded a signific ant correlation with toenail arsenic (r = 0.42, P = 0.001), similar to the correlation using energy-adjusted intake calculated from food res idue tables (r = 0.35, P = 0.001). These results illustrate the potent ial use of empirically derived weights for foods in estimating toenail levels of selected heavy metals and support the validity of published food residue data that are used to estimate mercury consumption.