Toxicity Effects of Fine Particulate Matter (PM_2.5) from Incomplete Solid Fuel Burning in Caenorhabditis elegans

Although the health risks associated with the use of biomass fuels have received widespread attention, there has been insufficient detailed research conducted on the toxic effects and toxicity generation mechanisms of PM_2.5 produced by the use of different sources of solid organic fuels. In this study, the synchronized L4-stage Caenorhabditis elegans (C. elegans) were exposed to the suspensions of the PM_2.5 samples collected from incomplete combustion products of rice straw, wheat straw, peanut straw, rapeseed straw and the branch of poplar and paulownia. Body length, the number of fertilized eggs, accumulation of lipofuscin, and levels of reactive oxygen species (ROSs) were measured to characterize developmental toxicity, reproductive toxicity, intestinal damage, and oxidative stress. The types and mass proportions of organic carbon (OC), elemental carbon (EC), water-soluble inorganic ions, and polycyclic aromatic hydrocarbons (PAHs) in PM_2.5 were determined. The results show that PM_2.5 generated from the combustion of the straw of oilseed crops such as peanuts and rapeseed has the most severe toxic effects on C. elegans. The toxicological mechanism was mainly mediated by severe oxidative stress and excessive generation of ROSs. The chemical characteristics of PM_2.5 have strong source-specificity, and its toxic effects are closely related to the high content of lipid-soluble PAHs in PM_2.5 from oilseed crop sources.