Blood lead levels in pregnant women in Nigeria: a cause for great concern
We read the article by Njoku and Orisakwe comparing blood lead levels (BLL) in rural and urban pregnant women in Eastern Nigeria with great interest . The authors found that BLL were substantially higher in rural areas than urban areas (135+/-160 vs 77+/-100 ug/dl). This in itself is an important finding: it may reflect a stronger reliance on locally grown foodstuffs in rural areas, combined with the effect of lead exposure from soil and dust from farming. However, the authors understate the importance of the overall BLL in this area of Eastern Nigeria (99+/-123 ug/dl). This level is substantially higher than has been found during pregnancy in other developing countries (e.g. Mumbai, India (geometric mean 6.4+/-1.69 ug/dl ) or in developed countries where there is a high environmental exposure (e.g. Sweden (smelter) 2.63+/-0.31 ug/dl ), or even in other countries in Africa (e.g. South Africa (median 2.3 ug/dl ). The reported levels are sufficient to cause overt symptoms of lead toxicity. As the authors note, there is free flow of lead though the placenta, with the ratio of fetal:maternal lead being about 0.7-0.9. Thus, the BLL of the newborn infants of these mothers will be about 80 ug/dl, and will rise further with exposure from breast-milk and local foods, and from the environment. These children are at extremely high risk of neurological damage and impaired growth and development, as stated by the authors. It is of note that the Centers for Disease Control and Prevention (CDC) in the USA recommends chelation therapy for BLL of >45 ug/dl in children . The authors provide some data on the lead levels in local staple foods: the high levels in these foods must reflect severe contamination of farmland. The BLL in these pregnant women is of great public health concern, not only for themselves, but also for their children and subsequent generations.
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