Aged biodegradable and non-biodegradable microplastics alter metolachlor toxicity in the gut and liver of crucian carp

Yonghua Wang; Yujia Shang; Jingying Guo; Guanhua Xu; Guanghua Lu; Xun Zhou; Jianchao Liu

doi:10.1016/j.jhazmat.2025.139212

Aged biodegradable and non-biodegradable microplastics alter metolachlor toxicity in the gut and liver of crucian carp

J Hazard Mater. 2025 Jul 10:496:139212. doi: 10.1016/j.jhazmat.2025.139212. Online ahead of print.

Authors

Yonghua Wang¹, Yujia Shang², Jingying Guo², Guanhua Xu², Guanghua Lu¹, Xun Zhou³, Jianchao Liu⁴

Affiliations

¹ State Key Laboratory of Water Cycle and Water Security, College of Environment, Hohai University, Nanjing 210098, PR China; Suzhou Research Institute, Hohai University, SuZhou 215100, PR China.
² State Key Laboratory of Water Cycle and Water Security, College of Environment, Hohai University, Nanjing 210098, PR China.
³ Suzhou Water Supply Co., Ltd., Suzhou 215002, PR China.
⁴ State Key Laboratory of Water Cycle and Water Security, College of Environment, Hohai University, Nanjing 210098, PR China; Suzhou Research Institute, Hohai University, SuZhou 215100, PR China. Electronic address: jianchao-liu@hhu.edu.cn.

PMID: 40652843
DOI: 10.1016/j.jhazmat.2025.139212

Abstract

Degradable plastic mulch films in agriculture, like non-degradable films, can generate microplastics (MPs) and interact with pesticides. Although some studies have examined MP-pesticide combined toxicity, aquatic organism research remains scarce. This study investigated the combined toxicities of metolachlor (MET) at environmentally relevant levels (3 μg/L) and high concentrations (300 μg/L) with aged MPs from non-degradable polyethylene (PE) and degradable polylactic acid (PLA) on crucian carp. The PE significantly increased MET accumulation in the liver and gut compared to MET alone group, whereas PLA exhibited the opposite trend. The MET alone exposure induced gut and liver damage in crucian carp, including oxidative damage, immune inflammatory responses, and metabolic disorders. Co-exposure of 3 μg/L MET with PE induced greater gut toxicity than with PLA, but at 300 μg/L MET, the MET + PLA combination was more gut toxic, primarily due to degradation of PLA. The toxic effects in the MET + PE group had a higher similarity to MET alone exposure. In contrast, MET+PLA groups showed more complex toxic effects and mechanism, which might be caused by the co-action of aged small particle PLA and MET. This study underscores the necessity of considering the ecological risk assessment of biodegradable films in agricultural applications.

Keywords: Aging; Biodegradable microplastics; Combined toxicity; Fish; Metolachlor.