Assessing the health risks from flooding and chemical contamination: a scoping review

Abstract Flooding can increase the mobilization of hazardous chemicals in the environment. This scoping review provides an overview of the evidence on how flood events effect our health through chemical contamination and describes the exposure pathways to guide prevention and response measures. Flooding includes surface water flooding, coastal flooding, river flooding, storm surge, monsoon rainfall and high tide. We found 110 papers that looked at the association between flooding and chemicals in the environment, with most studies looking at heavy metals, polyhydroxyalkanoates (PAHs), and arsenic. There was a lack of information on rural populations and studies on mobilisation of pesticides. Very few studies mapped or modelled human exposures, including for high-risk populations (e.g., children), and this remains an important evidence gap. Studies considering climate change highlighted the likelihood of chemical contamination and health risks to be exacerbated. Our results highlighted new pathways by which flood events mobilise chemicals and pose risks to human health (i.e., urban runoff, industrial sources). Although found extensively in the environment, gaps were identified in the evidence for pesticides, microplastics and heavy metals. Limited studies reported response measures to address the chemical contamination linked to flooding despite the health risks likely to increase due to poor infrastructure and management measures despite the extent of contaminated land and landfill sites. A dual risk management strategy (i.e., the coordinated management of both flood-related and chemical release risks is required to address flooding events, chemical releases, and health impacts.