Impact of exposure to phenols during early pregnancy on birth weight in two Canadian cohort studies subject to measurement errors
- DOI
- Language of the publication
- English
- Date
- 2018-08-10
- Type
- Article
- Author(s)
- Lester, Fiona
- Arbuckle, Tye E.
- Peng, Yingwei
- McIsaac, Michael A.
- Publisher
- Elsevier
Abstract
Background It is of interest to know whether early pregnancy exposure to phenols such as bisphenol-A (BPA) or triclosan (TCS) negatively impacts birth weight outcomes. Exposure to these chemicals is widespread in the Canadian population but obtaining accurate measurements of average exposure is difficult because these chemicals are rapidly excreted from the body, causing body levels to fluctuate both within and between days, as observed in a recent Canadian study (P4). This measurement error can attenuate the estimated effects of exposures. Methods Data from two Canadian cohort studies, the Plastics and Personal-care Products use in Pregnancy (P4) Study and the Maternal-Infant Research on Environmental Chemicals (MIREC) Study, such that all participants with complete BPA or TCS exposure and outcome data were used (MIREC n = 1822, P4 n = 68). We used regression calibration to correct for the attenuating effects of exposure measurement error when modeling the effect of first trimester BPA or TCS exposure on four birth weight outcomes: birth weight (BW), low birth weight (LBW), small for gestational age (SGA) and large for gestational age (LGA). Specific gravity, time of day, and time since last urine void were also controlled in the analysis. Results TCS exposure has a marginally significant association with SGA only with odds ratio 0.87 and 95% confidence interval (0.74, 1.00). It also has a marginally significant association with LGA in male offspring with odds ratio 1.11 and 95% confidence interval (1.00, 1.25). The effects of BPA on the four birth outcomes were insignificant. Conclusions Increased TCS exposure during pregnancy is marginally associated with decreased odds of having SGA offspring. It is possibly associated with decreased BW in males and decreased odds of LBW, though these associations were not present in measurement error corrected models. TCS is possibly associated with increased odds in male offspring of being LGA, though this relationship was not present in models not corrected for measurement error. The study finds no significant effects of BPA on birth weight outcomes, which may be due to more severe measurement error in a single observation of BPA.
Plain language summary
Health Canada is responsible for the assessment and management of health risks to Canadians associated with exposure to products and chemicals in the environment. Bisphenol A (BPA) and triclosan are two chemicals frequently measured in urine. Both these chemicals are rapidly eliminated from the body after exposure. Triclosan is used in a number of consumer products and in health care settings as an anti-microbial or preservative agent. BPA is used in the manufacture of polycarbonate plastics and in paperboard packaging, adhesives, and thermal receipts and is also found in epoxy resins used to line metal food and beverage cans. Research is limited on potential effects of exposure to elevated levels of these chemicals during pregnancy. In this collaborative study with Queen’s University, triclosan and BPA were measured in urine of pregnant women from the Maternal-Infant Research on Environmental Chemicals (MIREC) Study and the Plastics and Personal-care Product use in Pregnancy (P4) Study. Infant birth weight and gestational age at delivery were recorded. While most of the women had only a single urine sample analyzed, others provided multiple urine samples that could be used to evaluate how an individual’s exposure varied over time. With the latter information, any estimated risks could be adjusted for the variability in exposure. This study did not find any significant negative associations between these chemicals and infant birth weight. As there was substantial variability in urinary concentrations of BPA within an individual (and less so for triclosan), having only a single urine sample per woman may not be a good estimate for her true average exposure.
Subject
- Health,
- Health and safety