Acute toxicity of the chloroacetanilide herbicide butachlor and its effects on the behavior of the freshwater fish Tilapia zillii

Abstract

Acute toxicity of butachlor, a chloroacetanilide herbicide (2-chloro-N-[2, 6-diethylphenyl] acetamide) to Tilapia zillii, was studied in a semi static bioassay. The 24, 48, 72 and 96 h LC 50 values (with 95% confidence limits) estimated by probit analysis were 3.13 (2.88 to 4.61), 1.93 (0.63 to 4.41), 1.27 (0.59 to 1.92) and 1.25 (0.60 to1.85) mgl-1 , respectively. There were significant differences (p<0.05) in the LC 50 values obtained at different exposure times and the safe levels estimated by different methods varied from 1.25×10-1 to 1.25×10-5 mgl-1. There were dose and time dependent increase in mortality rate due to exposure to the herbicide. Stress signs in form of hyperactivity, erratic swimming, skin discoloration, vigorous jerks of the body followed by exhaustion and death were observed. The 96 h LC 50 of 1.25 mgl-1 obtained indicate that the herbicide was toxic to T. zillii. Agricultural use of butachlor in the environment, especially, near water bodies, must be restricted to avoid the severe risk associated with the use of the pesticide.

Potential Health Risks of Chloroacetanilide Herbicides: An In Silico Analysis

“…For example, one study has shown that chloroacetanilide herbicides such as alachlor increase the likelihood of developing Parkinson's disease [25]. Ecotoxicological studies suggest that these herbicides are the causal agents for DNA damage and tumor induction in rats, fish, and human lymphocyte cells found in in vitro studies [26][27][28][29].…”

Impact of Lamda-Cyhalothrin on the Biochemical Parameters of Clarias gariepinus

“…Annune et al [22] and Olusegun [23] reported similar findings. Nwani et al [24] also reported "skin discolouration in Tilapia zilli exposed to the chloroacetanilide herbicide butachlor". Ikele et al [25] similarly observed that the "C. gariepinus normal darkly pigmentation in the dorsal and lateral parts was changed to very light pigmentation when exposed to diethyl phthalate.…”