Child lead poisoning in South Africa: implications for psychological research

Abstract

Lead is a toxic heavy metal that is associated with lowered intelligence quotient scores, behavioural problems, and physical health impairments in children. Current consensus is that there is no safe level of child lead exposure and that even low doses of lead can have negative effects. Several reviews conducted in South Africa have revealed the sources and potential risk factors associated with child lead poisoning. However, no South African reviews have focused on the quality of studies focusing on child lead poisoning and psychological outcomes (intelligence, cognitive, and behavioural outcomes). This study reviews epidemiological studies of child lead poisoning with a particular focus on the association between child lead poisoning and psychological outcomes in South Africa over a 30-year time span (1986–2016). The review pays particular attention to study design, measurement, sampling, and confounding variables. Nine studies that measured child lead poisoning were included in the review. Just two of the nine studies (one cross-sectional and one follow-up) measured psychological outcomes and neither study adequately adjusted for confounding. In all studies, sampling was purposive and lead exposure indicators were suited to short-term acute exposure. There is, therefore, insufficient evidence to determine the magnitude of the association between child lead poisoning and psychological outcomes in South Africa. More rigorous epidemiological studies are needed to strengthen the evidence base. The article also highlights opportunities for psychological research in intervention studies and studies that are framed by an environmental justice agenda.