Prenatal exposure to phthalates and phenols and infant endocrine-sensitive outcomes: The MIREC study
- DOI
- Language of the publication
- English
- Date
- 2018-09-06
- Type
- Article
- Author(s)
- Arbuckle, Tye E.
- Agarwal, Amisha
- MacPherson, Susan H.
- Fraser, William D.
- Sathyanarayana, Sheela
- Ramsay, Tim
- Dodds, Linda
- Muckle, Gina
- Fisher, Mandy
- Foster, Warren
- Walker, Mark
- Monnier, Patricia
- Publisher
- Elsevier
Abstract
Background Anogenital distance (AGD) and the second to fourth finger (2D:4D) digit ratio may be early markers of in utero androgen exposure for the infant. Phthalates and phenols have been identified as endocrine disrupting chemicals. Objectives To study the association between prenatal exposure to phthalates, bisphenol A (BPA) and triclosan (TCS) and AGD and the 2D:4D digit ratios. Methods Single spot urine samples were collected in the first trimester from the MIREC Study and analyzed for phthalates and phenols. Anogenital distance (n = 394) at birth and 2D:4D digit ratios (n = 420) at 6 months were measured in male and female infants. Associations between maternal concentrations of phenols and phthalate metabolites and these outcomes were estimated using multiple linear regression models. Results In females, the anoclitoris distance (ACD) was negatively associated with mono-benzyl phthalate (MBzP) (β = −1.24; 95% CI −1.91, −0.57) and positively associated with mono-ethyl phthalate (MEP) (β = 0.65; 95% CI 0.12, 1.18) (masculinizing). In males, anopenile distance (APD) was positively associated with mono-n-butyl phthalate (MnBP) (β = 1.17; 95% CI 0.02, 2.32) and the molar sum of low molecular weight phthalates (ΣLMW). Female 2D:4D of the right hand was positively associated with MnBP and negatively with total BPA (masculinizing). Conclusions Significant associations were only observed for the long AGD metrics. Positive associations were observed between MnBP or LMW phthalates and APD in males. In females, prenatal MEP was associated with a masculinizing effect on ACD, while MBzP was associated with a feminizing effect. No significant associations were observed between prenatal phenols and AGD. Given the paucity of research on digit ratios and prenatal chemical exposures, it is difficult to say whether this metric will be a useful marker of prenatal androgen or anti-androgen exposure. Given the large number of associations examined, the statistical associations observed may have been due to Type 1 error. The inconsistencies in results between studies suggest that this issue is yet to be resolved.
Plain language summary
Health Canada helps to protect the health of Canadians by assessing and managing the risks associated with exposure to environmental chemicals. Phthalates are a group of chemicals used in plastics to soften and increase flexibility. Bisphenol A (BPA) is used to make a hard, clear plastic in many consumer products such as reusable water bottles and is also found as a protective lining inside metal food cans, as well as on paper receipts. Triclosan is used as a preservative and antimicrobial in many cosmetic and consumer products. These chemicals may be able to disrupt the endocrine system. One approach to studying potential effects on the reproductive system is to measure the distance between the anus and the genitals in infants. A few studies have reported that prenatal exposure to some phthalates was associated with a shorter anogenital distance (AGD) in male infants. This study measured phthalates, bisphenol A and triclosan concentrations in urine of pregnant women from the Maternal-Infant Research on Environmental Chemicals (MIREC) Study. In about 400 infants from this study, the distance between the anus and penis in boys and between the anus and clitoris in girls was measured. Higher levels of two phthalates in maternal urine were associated with a shorter anus-clitoris distance or a longer one, depending on the chemical studied. In male infants, higher urine levels of one kind of phthalate were associated with a longer anus-penile distance. No other associations observed. In conclusion, a few associations were observed between prenatal exposure to phthalates and anogenital distance in male and female infants. However, these results did not agree with what some other studies have reported. It is also likely that the results observed were due to chance. The inconsistencies in results between studies suggest that this issue is yet to be resolved.
Subject
- Health,
- Health and safety