Assessment of Maternal and Umbilical Cord Blood Lead Levels From Selected Informal Settlements in Nairobi County, Kenya

Abstract

Lead (Pb) is used in many manufacturing processes due to its useful properties. It is an important component in the manufacturing and recycling of lead batteries, manufacturing of paints and production of glazed pottery among others. However, Pb has no biological function; it is toxic, accumulates in biological systems and persists in the environment. The World Health Organization acknowledged that Pb is among the ten most toxic elements to human health. Pregnant women are vulnerable to the toxic effects of Pb as lead passes via the placenta to the developing fetus. As a result, it negatively affects the intelligence quotient (IQ) of the fetus since there is no brain barrier. Previous studies have indicated high levels of Pb in soil, water, and house dust in informal settlements. There is nonetheless scarce data on Pb exposure levels of mother-child pairs in Kenya despite the concerted efforts of phasing out leaded fuel and recently Pb in paint. The study was aimed at assessing the levels of lead in mothers and their newborns and potential sources of Pb exposure in selected informal settlements in Kenya. Blood from a total of 100 newborns (umbilical cord blood) and their mothers living in informal settlements was collected at the Pumwani Maternity Hospital and analyzed for levels of Pb using Inductively coupled plasma mass spectrometry (ICP-MS). The method of analysis was validated using ClinChek® Whole Blood Control, lyophilized, for Trace Elements, at different concentrations of Level I, II, III, procured from RECIPE Chemicals +instruments GmbH. A questionnaire was used to capture the likely sources of Pb exposure in the mother‟s environment. The median blood lead levels (BLLs) in newborns and their mothers were 2.1 and 26.7 μg/dL respectively. A high proportion of mothers (97%) had BLLs that exceeded the center for disease control (CDC) reference value of 5 μg/dL whereas, 25% of their newborns had BLLs above the 3.5 μg/dL reference value in children. A positive correlation (rs=0.65, p=0.000) between maternal BLL and newborn BLL, was observed which deduces that maternal BLL may be an important indicator for prenatal lead exposure. Proximity to dumpsite and residence in painted houses were significantly associated (p=0.004 and p=0.000 respectively) with elevated BLLs. The study has highlighted BLLs in mothers and their newborns and the key contributing factors that urgently call for interventions and strategies to reduce these exposures in informal settlements.