Journal Article
Characterization of phthalate exposure among pregnant women assessed by repeat air and urine samples
Adibi, JJ; Whyatt, RM; Williams, PL; Calafat, AM; Camann, D; Herrick, R; Nelson, H; Bhat, HK; Perera, FP; Silva, MJ; Hauser, R
Environmental Health Perspectives
ISSN: 0091-6765
EISSN: 1552-9924
National Institute of Environmental Health Sciences
Research Triangle Park
Background: Although urinary concentrations of phthalate metabolites are frequently used as biomarkers in epidemiologic studies, variability during pregnancy has not been characterized.
Methods: We measured phthalate metabolite concentrations in spot urine samples collected from 246 pregnant Dominican and African-American women. Twenty-eight women had repeat urine samples collected over a 6-week period. We also analyzed 48-hr personal air samples (n = 96 women) and repeated indoor air samples (n = 32 homes) for five phthalate diesters. Mixed-effects models were fit to evaluate reproducibility via intraclass correlation coefficients (ICC). We evaluated the sensitivity and specificity of using a single specimen versus repeat samples to classify a woman's exposure in the low or high category.
Results: Phthalates were detected in 85-100% of air and urine samples. ICCs for the unadjusted urinary metabolite concentrations ranged from 0.30 for mono-ethyl phthalate to 0.66 for monobenzyl phthalate. For indoor air, ICCs ranged from 0.48 [di-2-ethylhexyl phthalate (DEHP)] to 0.83 [butylbenzyl phthalate (BBzP)]. Air levels of phthalate diesters correlated with their respective urinary metabolite concentrations for BBzP (r = 0.71), di-isobutyl phthalate (r = 0.44), and diethyl phthalate (DEP; r = 0.39). In women sampled late in pregnancy, specific gravity appeared to be more effective than creatinine in adjusting for urine dilution.
Conclusions: Urinary concentrations of DEP and DEHP metabolites in pregnant women showed lower reproducibility than metabolites for di-n-butyl phthalate and BBzP. A single indoor air sample may be sufficient to characterize phthalate exposure in the home, whereas urinary phthalate biomarkers should be sampled longitudinally during pregnancy to minimize exposure misclassification.
Adult; Air Pollutants/*analysis/*urine; Air Pollution/*analysis; Biological Markers/analysis; Female; Humans; Infant, Newborn; *Maternal Exposure; Phthalic Acids/*analysis/*urine; Pregnancy; Sensitivity and Specificity; 0 (Air Pollutants); 0 (Biological Markers); 0 (Phthalic Acids)
