Prenatal Exposure to Phthalates and Phenols and Infant Anogenital Distance

Abstract

Measurement of endocrine sensitive endpoints, especially those that are sexually dimorphic, such as anogenital distance (AGD), can be used as sentinels for later adverse health effects arising from prenatal exposure to endocrine disrupting chemicals. Some studies have reported reduced AGD in male infants with increasing maternal urinary phthalate concentrations; one study reported an association in female infants, while others report no significant associations. Human studies of phenols and AGD are sparse.Phthalate and phenol concentrations were measured in 1st trimester urines in the pan-Canadian MIREC Study. After birth, short and long measures of AGD were conducted in 197 male and 195 female infants. Multiple linear regression models were created to examine the relationship between the AGD and the exposure of interest, including specific gravity and significant confounders as identified from the change-in estimate procedure. The same confounders were kept for all phenol and phthalate models.The anus-clitoris distance was negatively associated with the phthalate metabolite MBzP (β = -1.24; 95% CI -1.91, -0.57) and positively associated with MEP (β = 0.65; 95% CI 0.12, 1.18). The anopenile distance was positively associated with MnBP (β = 1.17; 95% CI 0.02, 2.32) and the molar sum of low molecular weight phthalates (ΣLMW) (β = 1.10; 95% CI 0.13, 2.08). No significant associations were observed between prenatal BPA or triclosan urinary concentrations and AGD in either sex.Given the large number of associations examined, the statistical associations observed may have been due to Type 1 error. The inconsistency in results between studies of prenatal phthalate exposure suggests that this issue is yet to be resolved.