Remediation via biochar and potential health risk of heavy metal contaminated soils

The serious damage to human health caused by soil heavy metals (HMs) pollution has always been a major problem in the field of public health. Although HMs pollution of soils has been efficiently remediated using biochar, the potential specific human health risks and their pathogeny during production and application are not known. The review provides a comprehensive summary of the current status, sources, and human health hazards of HMs contaminated soils; the physicochemical properties of biochar and its effects on the bioavailability of soil HMs; and the mechanisms and potential human health risks in using biochar for soil remediation. The results show that the interaction mechanisms between the biochar and soil HMs depend on the feedstock of biochar and pyrolysis temperature; biochar applications can directly or indirectly affect the bioavailability of HMs; several potential specific health risks such as dust pneumoconiosis, cytotoxicity, and respiratory diseases may be caused in the processes of biochar preparation and soil HMs remediation; additional recommendations are proposed for future research in areas, where significant knowledge gaps exist. This information can provide a meaningful reference for health management departments to formulate soil health prevention strategies.