A cross-sectional study of urinary cadmium concentrations in relation to dietary intakes in Uruguayan school children.

BACKGROUND: Cadmium (Cd) exposure has adverse health effects in children. Diet contributes to Cd exposure, but dietary components could affect body Cd levels. OBJECTIVE: To examine associations between diet and urinary Cd (U-Cd) in children. METHODS: In this cross-sectional study conducted in Montevideo, Uruguay, Cd exposure of 5-8 year old children (n = 279 with complete data) was assessed in first morning urine (U-Cd), a marker of long-term exposure, measured by ICP-MS and adjusted for specific gravity. Distribution of U-Cd was (median [5%, 95%]: 0.06 [0.02, 0.17] µg/L); data were natural-log-transformed (ln) for statistical analyses. Serum ferritin (SF), an indicator of iron stores, was measured in fasting samples. Trained nutritionists completed two non-consecutive 24-h dietary recalls with both child and caregiver present. Measures of iron, zinc, calcium and fiber intake, and the consumption of grains, root vegetables, milk, and foods rich in heme iron (white and read meats) and non-heme iron (legumes, spinach, broccoli, tomatoes, dried fruit) were derived. Multivariable ordinary least squares (OLS) and ordinal regressions were used to examine associations among tertiles of water Cd, SF, diet, and U-Cd. OLS models were further stratified by sex. RESULTS: In covariate-adjusted models, SF was not related to ln-U-Cd. Children in highest tertile of iron and zinc intake had lower ln-U-Cd: (-0.23 [-0.42, -0.03]) and (-0.25 [-0.44, -0.05]), respectively, compared to the reference group. Children consuming higher amounts of foods rich in heme iron had slightly lower ln-U-Cd (-0.17 [-0.36, 0.03]). High grain consumption was related to higher ln-U-Cd (0.25 [0.06, 0.45]). CONCLUSIONS: Diets rich in grains were related to higher urinary Cd levels among children living in the context of low Cd pollution. Higher intake of iron and zinc was related to lower Cd levels. Given that urinary Cd is mainly a marker of long-term exposure, these findings should be further corroborated.

Nutritional status and diet as predictors of children's lead concentrations in blood and urine.

Lead exposure remains an important public health problem. Contaminated foods may act as a source of lead exposure, while certain nutrients may reduce lead absorption. We examined the cross-sectional associations of dietary patterns and the intake of several nutrients and foods with blood (Pb-B) and urinary (Pb-U) lead concentrations in children (5-8y) from Montevideo, Uruguay. From two 24-hour recalls completed by caregivers, we derived the mean daily intake of select nutrients and food groups (dairy, milk, fruit, root vegetables, foods rich in heme and non-heme iron), as well as "nutrient dense" and "processed" food patterns. Pb-B (n=315) was measured using atomic absorption spectrometry; Pb-U (n=321) using ICP-MS. Pb-U was adjusted for specific gravity and log-transformed to approximate a normal distribution. Iron deficiency (ID) and dietary variables were tested as predictors of Pb-B and log-Pb-U in covariate-adjusted regressions. Median [5%, 95%] Pb-B and Pb-U were 3.8 [0.8-7.8] µg/dL and 1.9 [0.6-5.1] µg/L, respectively; ~25% of Pb-B above current U.S. CDC reference concentration of 5µg/dL. ID was associated with 0.75µg/dL higher Pb-B, compared to non-ID (p<0.05). Consumption of root vegetables was not associated with Pb-B or log-Pb-U. Higher scores on the nutrient-dense pattern were related with higher Pb-Bs, possibly due to consumption of green leafy vegetables. Dietary intake of iron or iron-rich foods was not associated with biomarkers of lead. Conversely, children consuming more calcium, dairy, milk and yogurt had lower Pb-B and log-Pb-U. Our findings appear consistent with existing recommendations on including calcium-rich, but not iron- or vitamin-C-rich foods in the diets of lead-exposed children, especially where the consumption of these foods is low.