Bisphenol A and phthalate metabolite urinary concentrations: Daily and across pregnancy variability
- DOI
- Language of the publication
- English
- Date
- 2014-09-24
- Type
- Article
- Author(s)
- Fisher, Mandy
- Arbuckle, Tye E.
- Mallick, Ranjeeta
- LeBlanc, Alain
- Hauser, Russ
- Feeley, Mark
- Koniecki, Diane
- Ramsay, Tim
- Provencher, Gilles
- Bérubé, René
- Walker, Mark
- Publisher
- Springer Nature
Abstract
Phthalates and bisphenol A (BPA) are high production volume and ubiquitous chemicals that are quickly metabolized in the body. Traditionally, studies have relied on single spot urine analyses to assess exposure; ignoring variability in concentrations throughout a day or over a longer period of time. We compared BPA and phthalate metabolite results from urine samples collected at five different time points. Participants (n=80) were asked to collect all voids in a 24 h period on a weekday and then again on a weekend before 20 weeks of pregnancy. During the second and third trimesters and in the postpartum period, single spot urines were collected. Variability over time in urinary concentrations was assessed using intraclass correlation coefficients (ICCs) and the sensitivity to correctly classify a single sample as high or low versus the geometric mean (GM) of all samples was calculated. We found low reproducibility and sensitivity of BPA and all phthalate metabolites throughout pregnancy and into the postpartum period but much higher reproducibility within a day. Time of day when the urine was collected was a significant predictor of specific gravity adjusted exposure levels. We concluded that, if the interest is in average exposures across pregnancy, maternal/fetal exposure estimation may be more accurate if multiple measurements, collected across the course of the entire pregnancy, rather than a single spot measure, are performed.
Plain language summary
Health Canada is responsible for the assessment and management of the health risks associated with exposure to chemicals in the environment. Phthalates and bisphenol A (BPA) are chemicals that are used in a variety of plastic consumer products. Because these chemicals are structurally similar to the hormones that our bodies produce, these chemicals may have harmful effects on the endocrine and reproductive systems, which can be of particular concern for pregnant women. Higher levels of exposure to these compounds mean higher levels of these compounds and their metabolites in the urine, although little is known about how much the levels may vary throughout the day or over a prolonged period of time. This is a significant question because biomonitoring studies typically assess exposure from a urine sample collected at a single point during the day. This study looked at urine levels of phthalates and BPA over an entire day (24 hour period) and throughout pregnancy by collecting and analyzing numerous urine samples from a group of 80 pregnant women. It was found that there was more variability between repeated urine samples for chemicals for which diet is likely to be the main source (e.g., BPA, di-2-ethylhexylphthalate) than for metabolites of chemicals used in personal care products (e.g., monoethyl phthalate, monobenzyl phthalate). Therefore, for those conducting or interpreting biomonitoring studies, in order to get the most accurate picture of BPA and most phthalate metabolite exposure levels, repeated measurements are required over an extended period of time, especially when diet is the main source of chemical exposure.
Subject
- Health,
- Health and safety