Human health risk assessment of historical metal pollution in vegetable gardens in the west and north of Melbourne, Australia

Anthropogenic activities in urban settings can result in the accumulation of harmful metal contamination in vegetable garden soils. Once present, metals are persistent in soil and tend to bioaccumulate in plants, thus entering the food chain when these plants are consumed, and potentially posing a hazard to human health. While several surveys have been conducted to assess metal uptake in vegetables, these surveys were conducted on agricultural soils, or pot plant experiments on spiked soils collected from agricultural fields. In some cases, vegetable garden soils were part of a larger survey that incorporated soils affected by mining and smelting (e.g. less sensitive land uses such as parks, recreational reserves, open public spaces). Very few peer-reviewed field trial studies have quantified the relationships between soil characteristics (soil organic matter, cation exchange capacity, pH, and electric conductivity) and plant phytoavailability. This type of study is important to inform human risk assessment to metals from vegetable consumption and oral intake of soil form gardening activities. The research presented here aimed to quantify the relationships between soil metal concentrations (Pb, Cd, Ni, and Cr) and soil physicochemical characteristics, concentration in vegetables, and associated human health risks from vegetable garden soil in the west and north of Melbourne, Australia. This research has presented a range of models with the potential for use in estimating Pb, Cd, Cr, and Ni concentrations in soil (total and bioaccessible) and vegetables grown in the west and north of Melbourne Australia. Thus, demonstrating the potential use of linear and stepwise regression models for use in risk calculations of potentially contaminated land. This research shows that despite the large consumption of homegrown vegetables and inadvertent consumption of garden soil, gardeners and their children are unlikely to be at risk to health as a result of gardening in soils with metal concentrations below the HIL A.