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. 2008 Apr;116(4):467-73.
doi: 10.1289/ehp.10749.

Characterization of phthalate exposure among pregnant women assessed by repeat air and urine samples

Jennifer J Adibi  1 , Robin M Whyatt, Paige L Williams, Antonia M Calafat, David Camann, Robert Herrick, Heather Nelson, Hari K Bhat, Frederica P Perera, Manori J Silva, Russ Hauser
Affiliations

Characterization of phthalate exposure among pregnant women assessed by repeat air and urine samples

Jennifer J Adibi et al. Environ Health Perspect. 2008 Apr.

Abstract

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.

Keywords: creatinine; indoor air; personal air; phthalates; pregnancy; specific gravity; urinary metabolites; variability.

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Figures

Figure 1
Figure 1
Urinary profile of phthalate metabolite concentrations in pregnant women and their newborns. Error bars represent upper bounds of 95% CIs.
Figure 2
Figure 2
Summary of Spearman coefficients of correlation between phthalate concentrations measured in environmental and biologic matrices. aUnadjusted for urinary dilution (data not available). bAdjusted for specific gravity. *p < 0.20. **p < 0.05.
See this image and copyright information in PMC

References

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