Lead exposure and increased food allergic sensitization in U.S. children and adults

Background: Whether blood lead levels are associated with sensitization to food allergens in adults and children is unclear. Prior studies have shown that exposure to lead is associated with atopic sensitization and modulation of several cytokines (eg, interleukin [IL]-12, IL-10, interferon [IFN]-γ, and IL-4 production) and with T-cell dysregulation and bias toward T helper 2 (Th2) activity. The objective of this work was to assess whether exposure to lead is independently associated with allergic symptoms and sensitizations in a large nationally representative sample of children and adults. Methods: We studied 2712 children and 4333 adults enrolled in the 2005-2006 cycle of the National Health and Nutritional Examination Surveys (NHANES). Participants were tested for serum-specific immunoglobulin E (IgE) levels to food allergens as well as blood lead levels. Food allergens tested included shrimp, egg, peanut, and milk. Logistic regression models adjusted for demographic factors, body mass index, history of asthma, smoking, housing characteristics, and current exposure to animals in the home, to assess the association of blood lead levels with sensitization to food allergens. Results: Median (interquartile range [IQR]) for serum blood was 0.87 μg/L (0.61 to 1.31) in children and 1.48 μg/L (0.92 to 2.34) in adults. At baseline, 672 (24.7%) of children participants and 719 (16.6%) of adult participants tested positive for increased sensitization to food allergens. A 2-fold increase in blood lead levels in adult participants was associated with increased sensitization to food allergens (odds ratio [OR], 1.11; 95% confidence interval [CI], 1.02 to 1.22). Blood lead was not associated with sensitization to food allergens among pediatric participants (OR, 0.95; 95% CI, 0.82 to 1.10). Conclusion: Exposure to lead was associated with increased odds of sensitization to food allergens in adult but not children participants.