Estimated dietary intake of nitrates, nitrites, and nitrosamines in U.S. women of child-bearing age

Multiple N-nitroso compounds have been observed in animal studies to be both mutagenic and teratogenic in nature. Human exposure to N-nitroso compounds and their precursors, nitrates and nitrites, can occur through exogenous sources, such as diet, drinking water, occupation, or environmental exposures, and through endogenous exposures resulting from the formation of N-nitroso compounds in the body. The National Birth Defects Prevention Study (NBDPS) collects information on topics relating to maternal health, pregnancy history, diet, substance abuse, occupation, residence, demographics and water use. Both cases and controls are interviewed using standardized sets of questions and the Willet Food Frequency Questionnaire as adapted for the NBDPS. Using information from control women with deliveries during 1997-2004, the relation between various maternal characteristics and intake of nitrates, nitrites, and nitrosamines from dietary sources was examined. First, estimates of these compounds for food items listed in the Short Willet Food Frequency Questionnaire were developed from available published literature. Dietary intake of nitrates, nitrites, and nitrosamines was calculated for each control mother based on the generated estimates. Multinomial logistic regression models were used to estimate odds ratios and 95% confidence intervals for the consumption of these compounds by self-reported race/ethnicity and other maternal characteristics. Median intake per day for nitrates, nitrites, total nitrites (5% nitrates + nitrites), and nitrosamines was estimated at 40.48 mg, 1.53 mg, 3.69 mg, and 0472 mug respectively. Controlling for daily caloric intake, factors important to predicting intake of these compounds included maternal race/ethnicity, state or area of residence, and folate intake, although additional factors were included for each specific model. Women whose reported race/ethnicity was other than non-Hispanic white were more likely to consume greater nitrates, nitrites, and total nitrites across all quartiles of intake compared to non-Hispanic white women (comparison mothers). However, for nitrosamines, non-Hispanic white women consumed more dietary nitrosamines than other women participating in the study across all quartiles of intake. These findings may be used to generate hypotheses for further research on the consumption of nitrosamines and N-nitroso precursors in the United States population, specifically in women of child-bearing age.