title: Examining the association between blood manganese and lead levels in schoolchildren in four selected regions of South Africa.
abstract: This study assessed the possibility of relationship between manganese and lead levels in blood in schoolchildren residing in different geographical regions of South Africa. A cross-sectional survey was carried out in schools of three cities: Cape Town (11 schools), Johannesburg (10 schools), Kimberley (six schools) and in the Northern Cape in three rural sites (four schools). A total of 1282 venous blood samples were collected from grade one children. The relationships between blood manganese and blood lead levels (treating each in turn as the response variable in order to adjust for the effect of confounding variables) were investigated by fitting mixed models. Mixed models were fitted with natural log (manganese concentration) as the response variable, and blood lead level as the principal explanatory factor. The model also included terms for centre and a centre by lead interaction and examined potential confounders. The important confounders were found to be gender, race and whether there was paint peeling from the outside walls. There was a significant centre by lead interaction (P<0.0001) with the effect of lead on ln(Mn) being different in the various centres. Mixed models fitted with blood lead level as the response variable and blood manganese as the principal explanatory factor, with terms for centre, a centre by manganese interaction and potential confounders, again found overwhelming evidence (P<0.0001) of a centre by manganese interaction. The study found great variability in both blood lead and manganese levels, both within and between sites, and there was not a consistent relationship between the two metals in the four sites.
authors.affiliation: South African Medical Research Council, P.O. Box 87373, Houghton 2041, South Africa. hrollin@mrc.ac.za
authors.forename: Halina B
authors.initials: HB
authors.lastname: Röllin
authors.forename: Angela
authors.initials: A
authors.lastname: Mathee
authors.forename: Jonathan
authors.initials: J
authors.lastname: Levin
authors.forename: Penny
authors.initials: P
authors.lastname: Theodorou
authors.forename: Halina
authors.initials: H
authors.lastname: Tassell
authors.forename: Ina
authors.initials: I
authors.lastname: Naik
authors.forename: Francois
authors.initials: F
authors.lastname: Wewers
mesh_terms: D002648:Child; D015331:Cohort Studies; D003430:Cross-Sectional Studies; D004784:Environmental Monitoring / Q000379:methods*; D004785:Environmental Pollutants / Q000097:blood*; D006801:Humans; D007854:Lead / Q000097:blood*; D008345:Manganese / Q000097:blood*; D013019:South Africa
chemical_list: D004785:Environmental Pollutants; D007854:Lead; D008345:Manganese