Prenatal and adolescent blood lead levels in South Africa: child, maternal and household risk factors in the Birth to Twenty cohort.
BACKGROUND
The risk factors for lead exposure in developing countries have not been fully described. This study looks at child, maternal and household factors associated with increased risk of lead exposure at birth and at 13 years of age in the Birth to Twenty cohort.


METHODS
Mothers were recruited from antenatal clinics in the Johannesburg-Soweto metropolitan area in 1990 (n=3273). Lead levels were analysed in cord blood collected at birth (n=618) and at 13 years (n=1546). Data on selected child, maternal and household factors were collected using a structured questionnaire in the third trimester and at 13 years of age. Statistical analyses were conducted to determine the associated risk factors.


RESULTS
The mean blood lead level at birth was 5.85 microg/dl, and at 13 years of age it was 5.66 microg/dl. The majority of children had blood lead levels above 5 microg/dl (52% at birth and 56% at 13 years). At birth, being a teenage mother and having low educational status were strong predictors for elevated cord blood lead levels. Being a male child, having an elevated cord blood level, and lack of household ownership of a phone were significant risk factors for high blood lead levels at 13 years.


CONCLUSIONS
Significant associations found in the study point to the low socio-economic status of lead-affected mothers and children. These poor circumstances frequently persist into later childhood, resulting in continued high lead levels. Thus broader measures of poverty alleviation and provision of better education may help decrease the risk of exposure.
Medical Research Council of South Africa, Environment and Health Research Unit, PO Box 87373, Houghton 2041, Johannesburg, South Africa. nisha.naicker@mrc.ac.za
Nisha
N
Naicker
Shane A
SA
Norris
Angela
A
Mathee
Yasmin E
YE
von Schirnding
Linda
L
Richter
D000293:Adolescent; D000328:Adult; D002648:Child; D002675:Child, Preschool; D015331:Cohort Studies; D004781:Environmental Exposure / Q000032:analysis*; D004784:Environmental Monitoring; D004785:Environmental Pollutants / Q000097:blood* / Q000378:metabolism; D005260:Female; D005312:Fetal Blood / Q000378:metabolism; D006798:Housing; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D007854:Lead / Q000097:blood* / Q000378:metabolism; D008297:Male; D018811:Maternal Exposure; D008875:Middle Aged; D011247:Pregnancy; D012307:Risk Factors; D013019:South Africa; D014505:Urban Population; D055815:Young Adult
D004785:Environmental Pollutants; D007854:Lead