1. 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 [1]. 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 [2]) or in developed countries where there is a high environmental exposure (e.g. Sweden (smelter) 2.63+/-0.31 ug/dl [3]), or even in other countries in Africa (e.g. South Africa (median 2.3 ug/dl [4]). 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 [5]. 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.


    1. Njoku CO, Orisakwe OE. Higher blood lead levels in rural than urban pregnant women in Eastern Nigeria. Occ Environ Med 2012.doi 10.1136/oemed-2012-100947.

    2. Raghunath R, Tripathi RM, Sastry VN, Krishnamurthy TM. Heavy metals in maternal and cord blood. Sci Total Environ 2000;250:135-41.

    3. Lagerkvist BJ, Ekesrydh S, Englyst V, Nordberg GF, Soderberg HA, Wiklund DE. Increased blood lead and decreased calcium levels during pregnancy: A prospective study of Swedish women living near a smelter. Am J Pub Health 1996;86:1247-52.

    4. Rudge CV, Rollin HB, Nogueira CM, Thomassen Y, Rudge MC, Odland JO. The placenta as a barrier for toxic and essential elements in paired maternal and cord blood samples of South African delivering women. J Environ Monitor 2009;11:1322-30.

    5. Centres for Disease Control. Lead. Managing elevated blood lead levels among young children: recommendations from the Advisory Committee on Childhood Lead Poisoning Prevention Committee 2002. Available at: (accessed 20 September 2012).

    Conflict of Interest:

    None declared

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