# Human health risk assessment of metal-contaminated soils in Sydney estuary catchment (Australia)

## TL;DR

This study assesses the health risks from metal-contaminated soils in Sydney, finding that lead from traffic poses the highest risk to children and adults.

## Contribution

The study introduces a consistent methodology for evaluating metal-related health risks in urban soils and highlights overlooked pollutants.

## Key findings

- Soil metal concentrations in Sydney are higher than in most global capitals, especially near the central business district.
- Lead in soils is strongly linked to traffic density and historic petrol use, posing non-carcinogenic risks at 32% of sites for children.
- Cadmium, nickel, and zinc pose no significant health risks, while copper and chromium may cause minor non-carcinogenic risks for children.

## Abstract

Sydney estuary catchment supports the largest city in Australia and provides essential eco-social and environmental services; however, the region has been influenced by extensive anthropogenic modification. Soil metal concentrations in the catchment had been studied previously; however, the current investigation was designed to determine the risk posed by these contaminants to human health. Soil metal concentrations were higher than observed in most global capitals and increased substantially in the south and south-east of the catchment and close to the central business district. Road-side soils and road dust contained the highest concentration of metals in the catchment. Lead in catchment soils was closely related to traffic density and sourced from the historic use of Pb in petrol. A human health assessment indicated that soil Cd, Ni and Zn posed no non-carcinogenic risk (NCR), or carcinogenic risk (CR) for children, or adults in Sydney estuary catchment and that Cu and Cr may pose minor NCR for children. Vehicle-related Pb raised the greatest human health risk in catchment soils and may pose NCR at 32% and 4.3% of sites for children and adults, respectively. Inconsistent analytical techniques used in CR and NCR evaluations produce incomparable assessments and a consistent` methodology is suggested to improve interpretation. Human health risk may well be higher than commonly calculated due to pollutants present in urban soil not being included in assessments.

The online version contains supplementary material available at 10.1007/s10653-024-01898-4.