Reductions in blood lead levels among school children following the introduction of unleaded petrol in South Africa

Abstract

Epidemiological studies have indicated that in the 1980s and early 1990s (a period in which petrol lead concentrations in South Africa ranged from 0.836 to 0.4 g/L), large proportions of urban South African children were at risk of excessive exposure to environmental lead. In 1991, when the maximum permissible petrol lead concentration in the country equaled 0.4 g/L, a study determined that the mean blood lead level among children attending inner city schools in the Cape Peninsula equaled 16 microg/dL, with well over 90% of children having blood lead levels equaling or exceeding the internationally accepted guideline level of 10 microg/dL. Socio economic status, housing conditions, and proximity of children's schools and homes to heavily trafficked roads were among the factors significantly associated with blood lead concentrations. In 1996, unleaded petrol was introduced in South Africa. A study undertaken in 2002 (at the same schools as in 1991), when unleaded petrol constituted around 30% of the market share of petrol in the country, has shown significant reductions in the mean blood lead concentration among Cape Peninsula inner city children and in the proportion of children with elevated blood lead levels. The mean blood lead level for the total sample (n = 429) of children whose mean age equaled 7 years (range: 5-11 years) was 6.4 microg/dL (range: 1.0-24.5 microg/dL) and 10% of children had blood lead levels equalling or exceeding 10 microg/dL. The mean blood lead levels among children attending schools in an inner city and in a less heavily trafficked periurban suburb were 6.9 and 4.8 microg/dL, respectively.