Prenatal high molecular weight phthalates and bisphenol A, and childhood respiratory and allergic outcomes

Background The prevalence of asthma and allergy is increasing in US children. In utero exposure to chemicals used in personal care products and plastics may contribute to increase in these diseases. Methods We quantified urinary concentrations of eight phthalate metabolites and bisphenol A in mothers twice during pregnancy in 1999-2000 in Salinas, California. We assessed probable asthma, aeroallergies, eczema, and spirometry in their children at age 7, and measured T helper 1 and T helper 2 cells in blood at ages 2, 5, and 7 (N = 392). We employed Bayesian model averaging to select confounders from additional biomarkers measured in this population and controlled for them in logistic and linear regressions. Results Monocarboxyisooctyl phthalate was associated with increased odds for probable asthma (odds ratio: 1.54, 95% CI: 1.12, 2.12), and with lower forced expiratory volume in one second (beta: -0.09 L, 95% CI: -0.15, -0.03) and forced expiratory flow from 25% to 75% of forced vital capacity (beta: -7.06 L/s, 95% CI: -11.04, -2.90). Several other associations were attenuated in final models that controlled for additional biomarkers. Conclusion Monocarboxyisooctyl phthalate was associated with lower respiratory health after controlling for related chemical exposure, which suggests that confounding by multiple chemical exposures should be considered in future research.