Temporal and spatial statistical analysis of children’s blood lead exposures in Australian oldest lead mining town of Broken Hill

Abstract

Blood lead (Pb) poisoning remains a worldwide health problem, affecting children residing in developed nations. One of these includes, Broken Hill, Australia’s oldest silver(Ag)-zinc(Zn)-lead(Pb) mining community. This study evaluates temporal, spatial, gender and ethnicity factors associated with a 20,229 childhood (0-5 years of age) blood lead level dataset from Broken Hill that spans a 25-year period (1991-2015). We conducted ANCOVA analysis to quantify the disparities of BLLs over different ages (0-4 years), gender and ethnic subgroups. Hot spot analysis was utilized to locate clusters of high BLLs and identify potential environmental risk factors. Over the study period, children aged 0-3 years old reported with the highest average BLLs (14.6 μg/dL) of all children assessed, with males having higher BLLs than females (p<0.01). Aboriginal children’s BLLs was higher (17.3 μg/dL) than non-Aboriginal children (13.8 μg/dL) (p<0.01). Specifically, during the 1st year following birth, Aboriginal-male BLLs increased at a greater rate than Aboriginal-female BLLs (p=0.011). In the 2nd year of life, female-Aboriginal BLLs increased at a greater rate than female-Non Aboriginals (p=0.001). Rapid accumulation of lead in blood after the first year of life was evident in some ‘hot spot’ areas adjacent to the mine site. In addition, other ‘hot spot’ more distant (2.2 km) from the mine site were identified indicating the interplay of additional unknown factors on BLLs. We will continue to analyse geographic hot spots using different spatial analysis methods to identify underlying environmental, social or human factors. In general, children’s BLL accumulation is dependant on age, gender and ethnicity. The data shows that while the whole of Broken Hill warrants lead-remediation to mitigate exposures, targeted intervention aimed at protecting Aboriginal children as well as all those residing in ‘hot spot’ areas is urgently required.