Sublethal concentrations of dichlorvos and paraquat induce genotoxic and histological effects in the Clarias gariepinus

Abstract

Non-target aquatic organisms such as fish may be impacted by agricultural activities through the runoff of pesticides from farms into aquatic ecosystems. In this study, the genotoxic (erythrocytic micronuclei) and histological effects of sublethal concentrations (1% and 10% of 96-h median lethal concentration (LC50) values) of two pesticides (dichlorvos and paraquat) were evaluated in Clarias gariepinus (the African Sharptooth Catfish) for 28 days. The 96-h LC50 of dichlorvos and paraquat against fingerlings of C. gariepinus was 730 µg/L and 50 µg/L, respectively. There was a significant dose-dependent increase (p<0.05) in micronuclei in the erythrocytes of exposed C. gariepinus (2.00±0.82 ‰ to 3.25±1.26 ‰ for dichlorvos and 2.25±0.96 ‰ to 4.75±0.96 ‰ for paraquat) compared to control (0.75±0.96 ‰) by day 28. Gill histological alterations such as mild to severe necrosis and blunting of secondary lamellae were observed in C. gariepinus exposed to higher sublethal concentrations of both pesticides. This study showed that non-target aquatic organisms like C. gariepinus may be at risk of adverse biological effects from exposure to pesticides from non-point sources. We recommend environmental monitoring and sensitization on responsible pesticide use to stakeholders. This will forestall potential adverse ecological effects in aquatic ecosystems.

In vivo genotoxic effects of commercial grade cypermethrin on fish peripheral erythrocytes

“…The MN test using fish erythrocytes have been reported in many species for the assessment of aquatic pollutants (Obiakor et al, 2021; Risjani et al, 2020; Verma et al, 2021). Significant induction of MN after exposure to commercial grade CYP detected in the present investigation are in agreement with earlier studies of pesticide exposure in other fish species (Bano et al, 2021; D'Costa et al, 2018; Ismail et al, 2018; Oladokun et al, 2020). Significant (p < .05) increase in MN frequency at both the tested concentrations in relation to control was observed, which peaked at seventh day of exposure and thenceforth exhibited a gradual decline.…”

Acute and sublethal intoxication of malathion in an Indian major carp, Labeo rohita: haematological and biochemical responses.

“…To ensure the sustainability of aquatic life from inadvertent exposure to contaminants and prevent human health effects from the consumption of contaminated fish, the evaluation of pesticides’ risk to non-target organisms like fish is imperative [ 21 ]. The pesticide exposed fishes exhibited a reduction in hematological values indicated anemia which may be due to erythropoiesis, haemosynthesis, and osmoregulatory dysfunction or due to an increase in the rate of erythrocyte destruction in hematopoietic organs [ 22 , 23 ].…”

Genotoxic, biochemical and histological biomarkers of subacute concentrations of paraquat and glyphosate in Nile Tilapia

“…The test compounds utilized in this study were herbicides-paraquat and glyphosate which were purchased from a chemical vendor at Ojota, Lagos, Nigeria. Paraquat (paraforce -active ingredient 200 g W.C. in 1 L) and glyphosate (Force Up-360 g glyphosate/L (in the form of 480 g/L Glyphosate-isopropylamine, salt) [25]. A stock solution of 1 g/L was prepared for each herbicide (paraquat: 5 mL in 1 L of dechlorinated tap water=1 g/L; glyphosate: 2.78 mL in 1 L of dechlorinated tap water=1 g/L) from which working solutions were computed.…”

“…They were transported in an open 25 L plastic container to the Environmental Toxicology laboratory at the University of Lagos. The fishes were acclimatized to the laboratory environment in a cylindrical plastic tank (60 L) three-quarter filled with dechlorinated tap water for 7 days [25]. The fishes were fed with Coppens feed (2 mm) twice daily.…”