Environmental chemical risk factors of breast cancer in Nigeria III: Metal: Lead

Abstract

Lead (Pb) is a metalloestrogen and a notable breast cancer risk factor. Lead is an International Agency for Research on Cancer (IARC) group 2A carcinogen. There is no level of exposure to lead that is known to be without harmful effects. Nigeria has literally every known environmental risk factor for lead exposure. Notable sources of lead exposure in Nigeria are lead in contaminated water, paints, artisanal gold ore processing, incineration of lead-containing waste and electronic waste (e-waste). Other sources of lead exposure are ‘tiro’—a lead-laden eye cosmetic, smoked fish particularly those displayed near highways with high vehicular traffic density, vegetables and root crops grown in mining communities, fruit exposed to lead-laden ripening agents, “Calabar chalk”—a lead-laden pica mostly consumed by pregnant women, and children’s toys. Prenatal vitamins supplements, paediatric medication syrups, traditional alcoholic and non-alcoholic drinks such as Kunnu and Zobo were also found as notable sources of lead consumption. Studies in Nigeria on blood lead (Pb) levels in children, pregnant women, and breast milk of nursing women were found to contain high lead levels. Lead exposure is preventable. Hitherto, the neurotoxicity of lead has been the dominant concern as regards lead exposure in children. The breast cancer risk factor now reinforces the zero tolerance for lead exposure.