Association of prenatal exposure to heavy metal mixtures and anogenital distance in newborns

BACKGROUND AND AIMS: Although the association between prenatal exposure to multiple metals and newborns' anthropometrics has been extensively studied, little is known about the reproductive toxicity and the endocrine disturbance characteristics of these metals. Hence, this study aimed to investigate the associations between prenatal exposures to a wide scope of metals to newborn's anogenital distance, as a marker of endocrine disruptions. METHODS: We used data of 889 mother-infant pairs, from two major hospitals in Israel. Associations between eight metals (arsenic, cadmium, chromium, mercury, lead, nickel, selenium and thallium) detected in maternal urine samples from day of delivery to anogenital distance index (AGI) at birth were examined. Adjusted estimates were calculated separately for males and females, using single-exposure models, and weights-quantile sums (WQS) models accounting for metals mixtures. RESULTS: Females found more susceptible to prenatal metals exposure as their z-scaled anoclitoris distance index (AGIac) was positively associated to chromium (β = .158 [95%CI:.061–.256]), nickel (β = .083 [95%CI:.005–.161]) and thalium (β = .140 [95%CI:.022–.258]). Their Z-scaled anofourchette distance index was positively associated to nickel (β = .079 [95%CI:.001–.158]). Z-scaled anoscrotal distance index (AGIas) was the only measure found associated to exposure in the WQS models (β = -.329 [95%CI:-.629– -.030]) and was associated to nickel and selenium. In the single-exposure models, chromium found positively associated (β = .111 [95%CI:.017–.206]) to the Z-scored anoscrotal distance index (AGIas) among males. CONCLUSIONS: The results suggest prenatal exposure to chromium, nickel and thallium may be associated to alterations of females AGD, while chromium, nickel and selenium to changes in males AGD. Since AGD alterations could represent wider endocrine interruptions, the effects of these metals on biological and chemical mechanisms during the vulnerable period of pregnancy should be further investigated. KEYWORDS: Prenatal Exposure; Pregnancy; Anogenital-Distance; Metals; WQS