Light Aging of Plastic Films Causes Nerve Damage Due to the Additives Released into the Water

Agricultural plastic mulching films are the main source of plastic pollution in farmlands. Long-term exposure to light radiation may cause their aging and degradation, and precipitation and irrigation further promote the release of additives into the water, posing a potential threat to the ecological environment. This study systematically investigated the changes in the physical and chemical properties of the film during aging and the neurotoxic effects of its leachate. The results showed that light radiation promoted the presence of oxygen-containing functional groups, increasing with the degree of aging, which facilitated the release of plastic additives. The toxicity assessment using the Caenorhabditis elegans model indicated that high concentrations of leachate could significantly inhibit the locomotion ability of the nematode. It is notable that the exudates from the photoaging film had a stronger inhibitory effect on the locomotion behavior of the nematode. Further analysis revealed that the aged film leachate reduced the content of key neurotransmitters in the nematode. Molecular biology studies showed that this neurotoxic effect was closely related to the expression inhibition of neurotransmission-related genes (dop-3, eat-4, mod-1, and unc-47). This study provides important scientific evidence for assessing the environmental risks of agricultural plastic mulching film pollution.