Feasibility of a non-invasive retrospective determination of Methylmercury Elimination During Pregnancy

Abstract Prenatal methylmercury (MeHg) exposure remains a priority health concern, particularly among fish eating populations. Yet, the kinetics of methylmercury (MeHg) metabolism and elimination in pregnant women and the fetus remain poorly understood. Measurements in non-pregnant women and men show that a wide variation in MeHg elimination rates can exist (t 1/2 <30 to > 120 days), whereby ‘slow eliminators’ will be prone to accumulating the highest MeHg levels. Because MeHg transfer across the placenta is rapid, determinations of MeHg kinetics in pregnant women will directly inform the susceptibility of the fetus to excess MeHg exposure from fish consumption. Here, we assess the feasibility of determining MeHg exposure profiles and elimination rates in fish-eating pregnant women via a non-invasive longitudinal Hg analysis using laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) of single strands of hair collected postnatally. Hair profiles completed for four subjects showed elevated Hg levels in three fish eaters compared to a non-fish eater. Fish-eating pregnant women were identified by characteristic profiles of peaks and decay of Hg over ~ 240 days spanning the 1st to 3rd trimester. MeHg elimination rates extracted from the Hg profiles showed a wide range of half-lives between individual women (t 1/2 = 25 to > 130 days). Elimination rates were also seen to increase two-fold from 1st to 3rd trimester in two individuals. This study establishes that individualized determinations MeHg elimination kinetics in pregnant women can be readily made and warrants further investigation to ultimately contribute to strategies to minimize fetal exposure.