Blood lead levels among Broken Hill children born 2009-2015: a longitudinal study to inform prevention strategies.

Objectives: To describe blood lead levels (BLLs) and their distribution among children in Broken Hill, New South Wales (NSW), at each of the scheduled testing points aligned with childhood immunisation and to determine how BLLs change over time for individual children. These data can inform action to prevent future lead exposure in Broken Hill children.

Study Type: Retrospective longitudinal study.

Methods: Data were extracted from the Lead Management Program ACCESS database on children born between 2009 and 2015 and living in Broken Hill. BLLs were calculated using capillary blood collected via finger prick, classified according to specific blood lead thresholds and grouped according to the testing schedule. A subset of children tested at each of the first three annual testing points provided data to determine the blood lead trajectories for individual Broken Hill children. Data were analysed using SPSS and ArcGIS.

Results: At the first test at 12 months, around half the children recorded a BLL of <5 µg/dL, one in three had a BLL of 5-9 µg/dL and one in five had a BLL of ≥10 µg/dL. A similar pattern was observed for subsequent test points at 18 months, 2 years, 3 years and 4 years. Of the 336 children who had results recorded at each of the 12-month, 2-year and 3-year test points, BLLs in around one-third remained below the recommended threshold of 5 µg/dL. Another one-third of these children had at least one test result ≥10 µg/dL, and the BLL in the remainder did not exceed 5-9 µg/dL at any of the test points. The geospatial distribution of children with very high BLLs shows clustering of these children in some localities, as well as their widespread distribution throughout Broken Hill.

Conclusions: It should be possible to keep BLLs below 5 µg/dL for the majority of young children in Broken Hill throughout their preschool years. This could be achieved by an integrated prevention strategy that includes population-level interventions such as targeted zonal remediation for high-risk areas and early intervention for individuals during the first 12 months and beyond, particularly for those who may not benefit directly from targeted zonal remediation. Routinely collected data could be used to guide the development, and monitor the effectiveness, of these interventions.