Introduction
Catfish farming is practiced by around 80% of fish farmers in Nigeria, and it is the most popular variety of fish employed in aquaculture. As a result, the usage of agrochemicals for fish growth and sustainability has increased. On farms, various agrochemicals such as Formalin, Copper Sulphate, Malachite green, and Potassium Permanganate among others have been abused and/or misused (Adeyemo et al., 2011; Alarape et al., 2013). The adverse side effects of glyphosate and aminomethyl phosphonic acid, or metabolites, on soil, water quality, plant, animal, and human health have been studied extensively in recent years due to glyphosate's extensive use and accumulation in the environment and food products (Battaglin et al., 2014). In 2015, the World Health Organization (WHO) categorized the glyphosate herbicide as possibly human carcinogenic based on their most recent findings on its potential chronic negative effects (EFSA, 2015; Guyton et al., 2015).
Materials and Methods
Five adult Clarias gariepinus (300 ± 50 g) were collected from each of five active cultured fish markets in Ibadan, giving a total of 25 fish. The fish were pithed, and muscle, liver, and kidney tissues were aseptically harvested, sealed in sterile sample bags, kept on ice, and transported to the International Institute of Tropical Agriculture (IITA) for glyphosate residue analysis. Solid-phase extraction (SPE) and quantification followed Delmonico et al. (2014). Digestion tubes were cleaned with water, distilled water, and 0.5% HCl, then dried. Homogenized tissue samples (0.5 mL) were placed in Pyrex tubes, after which 20 mL of an ammomethyl-phosphonic–nitric acid mixture (5:2:5) was added. Samples were digested for 2.5 hours at 25°C under a condenser, cooled, and diluted to 25 mL with ultrapure water. The mixtures were shaken for 10 min and centrifuged at 5,000 rpm for 5 min. Supernatants were analyzed using Reverse Phase LC (Agilent Technologies) with a C18 column (5 µm, 120 ��, 4.6 × 250 mm) and methanol/water (90:10) as the mobile phase at 1 mL/min for 30 min. The SPE-LC method was validated for specificity, linearity, sensitivity, accuracy, precision, and matrix effect resistance.
Results
The results showed that glyphosate residues were recorded in all the seventy-five (75) fish tissue samples obtained from the selected fish markets in the Ibadan metropolis and all residue concentrations were above both the recommended Acceptable Daily Intake (ADI) of 1.0 mg/kg (1 × 10���3 mg/L) and Maximum Residue Limits (MRL) of 0.01 mg/kg (1 × 10���5 mg/L). Isopropylamine has the highest residue concentration followed by N-Phosphonomethyl and Aminomethylphosphonic Acid (AMPA), while N-Acetyl Glyphosate has the least residue concentration across the sampled markets.
Discussion
The detection of glyphosate residues in the fish organs and muscles in this study confirmed the use of several glyphosate-based herbicides (Force-Up, Vinash, Para force, and Round-Up) on the fish farms (fish as a non-target organism) in Nigeria (Alarape et al., 2024), use of banned pesticides like pyrethroids, organophosphates, carbamates, and organochlorine in agricultural products in Bangladesh (Jallow et al., 2017) and Ghana (Essumang et al., 2009). Although glyphosate-based herbicides were not used directly on fish, environmental contamination may be a possible source of the herbicide residues found in fish in the research location where such herbicides are used on farms close to fish farms. The presence of residues of glyphosate and its metabolites in readyto-eat fish calls for holistic, systematic, and effective risk management strategies towards monitoring pesticide/herbicide usage in aquaculture production and ensuring the provision of wholesome fish and fish products for the consumers.
References
Adeyemo, O. K., Alarape, S. A., and Emikpe, B. O. (2011). Reprotoxic effect of malachite green on african catfish Clarias gariepinus (burchell 1822). J. Fish. Aquatic Sci. 6 (5), 563–570. doi:10.3923/jfas.2011.563.570
Alarape, S. A., Ajani, F., Adeyemo, O. K., and Shobiye, J. O. (2013). Effect of copper sulphate on spawning success in african catfish (Clarias gariepinus, burchell 1822). J. Fish. Aquatic Sci. 8 (6), 714–720. doi:10.3923/jfas.2013.714.720
Alarape, S.A., Adebiyi. O.E., Adetunji, V.E., Ogundijo, O.A., Aina, O.O. and Adeyemo, O.K. (2024):
Histopathological Effects and Micronucleus Assay of Glyphosate-based Herbicides on Cultured African Catfish (Clarias gariepinus, Burchell 1822). Savannah Veterinary Journal, 7(1): 9-21. doi: https//:doi.10.36759/svj.2024.215..
Battaglin, W. A., Meyer, M. T., Kuivila, K. M., and Dietze, J. E. (2014). Glyphosate and its degradation product AMPA occur frequently and widely in U.S. soils, surface water, groundwater, and precipitation. J. Am. Water Resour. Assoc. 50, 275–290. doi:10.1111/jawr.12159
Delmonico, E. L., Bertozzi, J., de Souza, N. E., and Oliveira, C. C. (2014). Determina����o de glifosato e ��cido aminometilfosf��nico para erifcar a qualidade da ��gua de abastecimento p��blico utilizando EFS e CLAE. Acta. Sci. Technol. 36, 513–519. doi:10.4025/actascitechnol.v36i3.22406
EFSA (2015). Peer review of the pesticide risk assessment of the potential endocrine disrupting properties of glyphosate. EFSA J. 13 (11), e04979. doi:10.2903/j.efsa.2017.4979
Essumang, D. K., Togoh, G. K., and Chokky, L. (2009). Pesticide residues in the water and fish (lagoon tilapia) samples from lagoons in Ghana. Bull. Chem. Soc. Ethiop. 23 (1), 19–27. doi:10.4314/bcse.v23i1.21294
Guyton, K. Z., Loomis, D., Grosse, Y., El Ghissassi, F., Benbrahim-Tallaa, L., Guha, N., et al. (2015).
Carcinogenicity of tetrachlorvinphos, parathion, malathion, diazinon, and glyphosate. Lancet Oncol. 16 (5), 490–491. doi:10.1016/S1470-2045(15)70134-8
Jallow, M. F. A., Awadh, D. G., Albaho, M. S., Devi, V. Y., and Thomas, B. M. (2017). Pesticide Knowledge and safety practices among farm workers in Kuwait: results of a survey. Int. J. Environ. Res. Publ. Health 14, 340. doi:10.3390/ijerph14040340