Migration and toxicity of toltrazuril and its main metabolites in the environment

Meixia Huo; Wenjin Ma; Kaixiang Zhou; Xiangyue Xu; Zhenli Liu; Lingli Huang

doi:10.1016/j.chemosphere.2022.134888

Migration and toxicity of toltrazuril and its main metabolites in the environment

Chemosphere. 2022 Sep:302:134888. doi: 10.1016/j.chemosphere.2022.134888. Epub 2022 May 10.

Authors

Meixia Huo¹, Wenjin Ma¹, Kaixiang Zhou², Xiangyue Xu¹, Zhenli Liu³, Lingli Huang⁴

Affiliations

¹ National Laboratory for Veterinary Drug Safety Evaluation, Huazhong Agriculture University, Wuhan, 430070, China; MOA Laboratory for Risk Assessment of Quality and Safety of Livestock and Poultry Products, Hubei, 430070, China; College of Veterinary Medicine, Huazhong Agriculture University, Wuhan, 430070, China.
² National Reference Laboratory of Veterinary Drug Residues (HZAU), Huazhong Agriculture University, Wuhan, 430070, China; MOA Key Laboratory for Detection of Veterinary Drug Residues, Huazhong Agricultural University, Wuhan, Hubei, 430070, China; College of Veterinary Medicine, Huazhong Agriculture University, Wuhan, 430070, China.
³ National Laboratory for Veterinary Drug Safety Evaluation, Huazhong Agriculture University, Wuhan, 430070, China; MOA Laboratory for Risk Assessment of Quality and Safety of Livestock and Poultry Products, Hubei, 430070, China; National Reference Laboratory of Veterinary Drug Residues (HZAU), Huazhong Agriculture University, Wuhan, 430070, China; College of Veterinary Medicine, Huazhong Agriculture University, Wuhan, 430070, China.
⁴ National Laboratory for Veterinary Drug Safety Evaluation, Huazhong Agriculture University, Wuhan, 430070, China; MOA Laboratory for Risk Assessment of Quality and Safety of Livestock and Poultry Products, Hubei, 430070, China; National Reference Laboratory of Veterinary Drug Residues (HZAU), Huazhong Agriculture University, Wuhan, 430070, China; MOA Key Laboratory for Detection of Veterinary Drug Residues, Huazhong Agricultural University, Wuhan, Hubei, 430070, China; College of Veterinary Medicine, Huazhong Agriculture University, Wuhan, 430070, China. Electronic address: huanglingli@mail.hzau.edu.cn.

PMID: 35561774
DOI: 10.1016/j.chemosphere.2022.134888

Abstract

Veterinary drugs heavily used in livestock are passed into the environment through different ways, resulting in risks to terrestrial environments and humans. The migration of toltrazuril (TOL), an important anticoccidial drug used intensively in livestock, and its main metabolites between the chicken manure compost, soil and vegetables was investigated, and then the impacts of TOL on the soil bacterial community and ARGs, soil enzyme activities and phytotoxicity were detected. In the process of aerobic composting for 80 days, except for toltrazuril sulfoxide (the degradation half-life was 59.74 d), TOL and ponazuril (PON) were not significantly degraded. However, TOL and its metabolites were significantly degraded in fertilized soil, and the degradation half-life was 28.17-346.50 d. Among the three drugs, only PON could migrate from soil to vegetables, and the residual concentrations of PON in lettuce and radish were 2.64-70.02 μg kg^-1 and 0-2.80 μg kg^-1, respectively. Moreover, TOL and its main metabolisms had no significant effect on the bacterial community structure and the abundance of antibiotic resistance genes during composting, but affected the microbial activity in the soil. The presence of TOL and its main metabolites reduced soil urease activity, increased catalase activity, and decreased alkaline phosphatase activity at the beginning and then increased slightly. They had negative effects on plant growth. Compared with the control group, the inhibition rates of TOL and its metabolites on lettuce and radish seed germination were 8.33% and 26.74% respectively, and the inhibition rates of root elongation length were 25.88% and 34.45% respectively. These results showed that TOL and its main metabolites were ineffectively removed by aerobic composting, and could be migrated from composting to soil and vegetables, which had adverse effects on soil enzyme activity and plant growth. Therefore, its environmental ecological risk and human health risk needs to be further evaluated.

Keywords: Compost; Phytotoxicity; Soil enzyme activity; Toltrazuril; Vegetables.

MeSH terms

Animals
Anti-Bacterial Agents / pharmacology
Composting*
Genes, Bacterial
Lactuca
Livestock
Manure / microbiology
Raphanus*
Soil / chemistry
Soil Microbiology
Triazines
Vegetables

Substances

Anti-Bacterial Agents
Manure
Soil
Triazines
toltrazuril