Elevated prenatal methylmercury exposure in Nigeria: evidence from maternal and cord blood.

Methylmercury is a neurodevelopmental toxicant that is globally distributed though little is known about prenatal exposures in sub-Saharan Africa. The objective of the current study was to measure total mercury levels in cord blood and maternal blood from 95 mother-newborn pairs recruited from hospitals in Nnewi, Nigeria. The secondary aims of the study were to explore if demographic and dietary factors were associated with blood mercury levels, and to explore if mercury levels were associated with any self-reported health outcome and childbirth outcome. Maternal blood mercury levels averaged 3.6 µg L(-1) and ranged from 1.1 µg L(-1) to 9.5 µg L(-1). Cord blood mercury averaged 5.1 µg L(-1) and ranged from 1.2 µg L(-1) to 10.6 µg L(-1). The mean ratio of mercury in paired cord blood to maternal blood was 1.5 and it ranged from 0.4 to 3.2. Mercury in maternal and cord blood were significantly correlated (r=0.471). More than one-third of mothers reported eating fish at least once per day, and a weak (p=0.08) fish consumption-related increase in blood mercury was found. Cord blood mercury was positively and significantly associated with birth weight and length, and head and chest circumference. Mercury levels in 36% of the participants exceeded the biomonitoring guideline associated with the United States Environmental Protection Agency (U.S. EPA) reference dose for mercury. The study shows that pregnant women and their newborns are exposed to methylmercury and that their exposures are higher compared to general populations sampled from other regions of the world.

Towards prenatal biomonitoring in eastern Nigeria: assessing lead levels and anthropometric parameters of newborns.

The purpose of this study is to measure maternal blood lead level (BLL) and cord BLL in Nigeria and to compare Nigerian data with other data. We investigated the association among maternal and cord BLLs, and some anthropometric parameters of their babies. BLL was measured in the umbilical and maternal blood samples (using inductively coupled plasma / mass spectrometry (ICP-MS)) of 119 women who delivered at three different hospitals in Nnewi, South Eastern Nigeria. Anthropometric variables of the babies (head circumference, abdominal circumference, birth weight, birth length, crown rump length) were measured. Lead was detected at >10 µg/l in 10.9 percent of the maternal and 3.4 percent of the cord blood samples. The maternal BLL was 6.19 ± 2.77(mean ± SD) µg/dl while cord BLL was 4.75 ± 2.59(mean ± SD) µg/dl. With the exception of cord BLL and crown rump length positive correlation (R=0.204, P=0.026), neither the maternal nor the cord BLL showed any significant association with any of the children's anthropometric parameters.