Biochemical and genotoxic effects of a commercial formulation of the herbicide tebuthiuron in Oreochromis niloticus of different sizes

Abstract

Pesticides are serious contaminants because they are designed to eliminate pests, but they also affect non-target species. The present study aimed to evaluate the biochemical and genetic effects of the herbicide tebuthiuron in Oreochromis niloticus of different sizes. Thus, we analyzed biomarkers in small and large O. niloticus specimens exposed to 62.5, 125 and 250 mg L-1 of tebuthiuron for 72 hours. Fish exposed to 250 mg L-1 had high mortality rates; therefore, the data could not be used. The results showed an increase in EROD activity in fish exposed to 125 mg L-1 , but no GST alteration. Antioxidant enzymes GPx and CAT were altered only in the liver of treated fish compared to the control group: CAT decreased in large fish, and GPx increased in small fish. The MDA analysis did not evidence lipid peroxidation. High DNA damage in exposed small fish (not in large fish) was observed using comet assay, but a micronucleus test did not show mutagenicity. Moreover, a comparison between control groups with specimens of different sizes revealed that small fish are more susceptible than large fish to the tebuthiuron effects, since increased comet scores was observed only for smaller fish.

The use of biomarkers to study the effects of the mixture of diuron and hexazinone on small and large O. niloticus

“…Previous studies by our group (Franco-Bernardes et al, 2014) showed similar data for Nile Tilapia exposed to the herbicide tebuthiuron, and so did a study by Kanak et al (2014), in which the authors exposed this species to metal using antioxidant parameters. Both studies revealed greater responsiveness in small fish, corroborating the results of our work.…”

Induction of Micronuclei and Erythrocytic Nuclear Abnormalities in Peripheral Blood of Fish Cyprinus carpio on Exposure to Karanjin

“…Similar kinds of results were also seen by some other researchers [10]. None of the sub-lethal exposure days -24 h, 7 d, 14 d and 21 d showed the formation of micronuclei.…”

Green Manure Species for Phytoremediation of Soil With Tebuthiuron and Vinasse

“…This molecule [1-(5-tert-butyl-1,3,4-thiadiazol-2-yl)-1,3dimethylurea] has a systemic action and acts in the inhibition of photosystem II (Breitenbach et al, 2001). However, tebuthiuron can cause environmental damage since it is considered dangerous to the environment due to its high persistence and long half-life in the environment, moderate to extreme toxicity (Rodrigues and Almeida, 2011), low sorting capacity in soil (Koskinen et al, 1996), and high solubility in water (Franco-Bernardes et al, 2014). Hence, residual concentration is an extremely important factor, as it results in a greater potential for contamination.…”