Risk assessments and health impacts of heavy metal pollution

Abstract

<p indent="0mm">Heavy metal pollution is a serious global environmental issue, posing huge risks to food security and human health. As a typical biomarker of heavy metals, soil nematodes develop complex defenses in response to heavy metal exposures. Meanwhile, their gut microbiomes assist host resistance to heavy metals. Here we review the pollution status and assessment methods of heavy metals at home and abroad and summarize their effects on the behavior, physiology, and biochemistry of soil nematodes. Additionally, defense mechanisms of organisms against heavy metals are reviewed, including barrier functions of the cell wall and membrane, changes in active substances, metallothionein overexpression, and noncoding RNA regulation. We propose that the diversity and composition of the nematode gut microbiome can be used as a new indicator of heavy metal toxicity. Furthermore, long-term heavy metal exposure could lead to adaptive evolution, such as the emergence and enrichment of heavy metal hyperaccumulation, resistance, and detoxification genes. Additionally, we can map genetic changes, such as resistance mutations in genes and synergies of resistance, by quantifying the genome-level response of genetic variation under environmental stresses. Finally, we provide a prospect on the ecotoxicology of heavy metals and indicate that future research should focus on the current ecological environment and human health, explore the ecological role of soil fauna gut microbiome, and further understand the potential mechanism of occurrence and development of heavy metal toxicity and biological detoxification.