Metals and metalloids, many of which are human carcinogens, can be found in soil due to natural geology or human activities like mining, waste disposal, and fertilizer application. Despite potential causal links between soil metal/metalloid exposure and cancer, existing studies have not been comprehensively reviewed. This scoping review aims to provide an overview of studies examining associations between soil metal/metalloid levels and cancer burden in resident populations. A keyword-based literature search was conducted in Pubmed and Web of Science, yielding 51 studies that met the inclusion criteria. These studies, limited to 16 countries/territories, often focused on a single contaminated area. The most studied metals/metalloids were cadmium and arsenic, while the most studied cancer entities were lung and bladder. The majority of studies (67%) were ecological in design, with 82% reporting significant associations between soil metal/metalloid levels and cancer, while 60% of cohort and case-control studies reported significant associations. Frequent methodological limitations were noted, such as incomplete reporting of soil sampling, lack of formal exposure assessment and lack of adjustment for key confounders. The heterogeneity in reported results and methodologies, as well as reliance on ecological designs limit the strength of potential causal inferences. This review highlights the need for further high-quality research, particularly with the increasing availability of systematic soil surveys and harmonized cancer registration data. Overall, this review provides a summary of existing evidence on the relationship between soil metal/metalloid exposure and cancer, and identifies areas for future research to better understand this potential health risk.
Bartnicka et al. (Thu,) studied this question.
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