The association between elevated blood lead levels and violent behavior during late adolescence: The South African Birth to Twenty Plus cohort.

Epidemiological studies have shown the adverse neuro-behavioral health effects of lead exposure among children, in particular. However, there is lack evidence in this regard from developing countries. The main aim of this study was to assess the association between blood lead levels (BLLs) during early adolescence and violent behavior in late adolescence. Our study sample from the Birth to Twenty Plus cohort in Soweto-Johannesburg, South Africa included 1332 study participants (684 females). BLLs were measured using blood samples collected at age 13years. Violent behavior was evaluated using data collected at ages 15 to 16years using the Youth Self Report questionnaire. First, bivariate analysis was used to examine data for an association between lead exposure in early adolescence and violent behavior items during late adolescence. Principal Component Analysis (PCA) was used for dimensionality reduction and six violent behavior components were derived. Data were further analyzed for an association between BLLs at age 13years and violent behavior using PCA derived components; to determine the specific type(s) of violent behavior associated with lead exposure. Median whole BLLs were 5.6μg/dL (p<0.001). Seventy five percent of males and 50% of females had BLLs≥5μg/dL. BLLs ranging from 5 to 9.99μg/dL were associated with physical violence (p=0.03) and BLLs≥10μg/dL were associated physical violence and fighting (p=0.02 and p=0.01, respectively). When data were analyzed using continuous BLLs physical violence was associated with lead exposure (p<0.0001). Furthermore, males were more likely to be involved in violence using a weapon (p=0.01), physical violence (p<0.0001), and robbing others (p<0.05) compared to females. The results from this study show the severe nature of violent behavior in late adolescence associated with childhood lead exposure. They highlight the urgent need for preventive measures against lead exposure among children in low or middle income countries such as South Africa.