Simulation of Blood Lead Levels in Pregnant and Lactating Women in Osun State, Nigeria, Two Decades after Phase-out of Leaded Petrol

Abstract

Elevated Blood Lead Levels (BLL) during pregnancy and lactation is known to be due to endogenous release of lead from its main storage sites in the human body – the cortical bones (with half-life of 27 years) and the trabecular bones (with half-life of 16 years).  This release is due to the co-mobilization of lead together with calcium which is sourced from the bones during these periods of high requirement for calcium. While the level of such lead might be inconsequential for the mother, it could constitute a significant neurological and developmental health risk to the baby.  In this work, employing a Physiologically Based Kinetic Model previously developed by us, we estimated expected current BLL in pregnant and lactating women who had had various levels of exposure to leaded petrol before its 2003 phase-out in Nigeria.  Our results show that subjects born and raised in Osun state, Nigeria before 1996 and who had consequently been exposed to leaded petrol for a minimum of 8 years before its phase-out, will today have blood lead levels greater than the interventional level of 5 µg/dL recommended by the US Department of Human and Health Services for pregnant women.  This is a conservative assessment, and has not taken into consideration additional ongoing lead intakes from diet and other exposure sources, such as from artisanal gold mining.  This result therefore suggests that women aged 29 years and above will, during pregnancy and lactation, significantly benefit from interventions to mitigate endogenous lead release, for example via dietary calcium supplementation.