Prevalence of elevated blood lead levels in children with chronic neurologic disorders in Benin City, Nigeria

Background: Excess blood levels of lead in humans are injurious to tissues and organs chief among which is the central nervous system. Children with chronic neurologic disorders (CNDs) with already compromised brain function are unduly predisposed to lead poisoning because of some aberrant conducts and behaviors inherent in CNDs. Such children are therefore at greater risk of further deterioration of brain functions should they have elevated blood lead. Objectives: To determine blood lead levels in children with CNDs as well as in apparently healthy controls. Methods: The case control, prospective and cross sectional study involving 139 children (89 or 64% males and 50 or 36.0% females) aged 1-15 years (mean ± SD: 6.54±4.04 years) and recruited from the Neurology Clinic (COPD) of the University of Benin Teaching Hospital (UBTH) Benin City was carried out between January and March of 2013. Same number of apparently children matched for age and gender served as controls. A semi structured, pre tested and researcher administered questionnaire was used in obtaining relevant information from the parents or guardians of study subjects. Atomic absorption spectrophotometer was used in determining the blood lead levels while the Vineland Social Maturity Scale was used to assess personal and social sufficiency among subjects while socioeconomic classification of the subjects was in accordance with the recommendations of Ayodeji. Results: Subjects consisted of 80 (57.5%) with epilepsy, 24 (17.3%) with mixed forms, 23 (16.5%) with cerebral palsy, 8 (5.8%) with attention deficit and hyperactivity disorder and 4 (2.9%) mental retardation. Mean BLL in subjects with CNDs of 25.05±16.65 μ g/dl (range: 8-72 μ g/dl) was significantly higher than the value in controls (19.24±10.17 μ g/dl; range:8-53 μ g/dl )(t=3.51, p=0.00). One hundred and one (72.7%) subjects compared to 111 (79.9%) controls had elevated blood lead levels eBLLs. Prevalence of eBLLs was independent of gender, age, family SES and nutritional status. Between subjects and Control show ever, gender (24.92±15.97μ g/dl vs 19.35±10.63 μg/dl;t=2.74= p=0.01/25.28±17.96μ g/dl vs 19.50±09.55μg/dl; t=2.01; p=0.04), age (11-15 years only) (36.36±18.56μ g/dlvs 19.45 ± 10.76 μ g/dl; t= 4.01; p=0.00) and family SES (24.67±17.12 μ g/dl vs 18.12±09.17 μ g/dl; t=3.42;p=0.00) significantly influenced the mean blood lead level (mBLL). mBLL was significantly higher in children with epilepsy and lowest in those with mental retardation (F=2.75; p=0.03). The only risk factor that predicted eBLLs was finger sucking (OR=2.56; p=0.04 95% CI=1.03-6.40). Conclusion/Recommendations: eBLLs is rampant in the study locale in both subjects and controls with the latter at heightened risk. Hand sucking is a proven risk factor for eBLLs. Such children and others predisposed to eBLLs should be protected through improved supervision, routine screening and intervention where necessary