Similarity in human health risk assessment using models of soil-blood lead levels (IEUBK) and non-carcinogenic condition (US EPA 2002)

Abstract

Soil lead (Pb) concentrations in Sydney estuary (Australia) catchment are substantially elevated and strongly associated with traffic networks. This study compared the health risk predictions of blood Pb levels (BLL) in children using the soil IEUBK model and an independent, non-carcinogenic human health risk (NCR) assessment using the soil US EPA 2002 model. The predictions by the two models were significantly correlated (p < 0.001) and showed similar spatial distributions, but the NCR model may be more stringent in protection of human health when exposed to soil Pb in relation to adverse health effect, as the warning soil Pb concentration from the BLL was 4.6-fold higher than that from the NCR. The empirical IEUBK model considers gastric phase adsorption only and of the three exposure pathways (ingestion, inhalation and dermal) assessed by the theoretical NCR model, ingestion was the major exposure route. The reason for the similarity in outcomes of the two models is unknown, however the close correlation may be due to broadly similar formulations and, or that neurological and non-carcinogenic risks may be related to the adverse effects of Pb on bodily function. Parallel studies of human health risk based on BLL and NCR models have not been attempted previously and this opportunity to compare results from the two health risk assessments employing the same soil metal data is therefore unique.

Keywords: Health risk prediction; IEUBK model; NCR model; Soil Pb; Sydney estuary catchment.