Subchronic Toxicity of a Terbufos-based Pesticide (Counter 15FC) in Adult Male Rats

Document Type : Original Article


1 Department of Biochemistry and Molecular Biology, Faculty of Science, University of Buea, PO Box 63 Buea, Cameroon

2 Department of Biochemistry, Faculty of Science, University of Bamenda, PO Box 39 Bambili, Cameroon

3 Medical Research and Applied Biochemistry Laboratory (Drug Discovery and Development Research Unit) University of Buea, Cameroon


This study aimed at evaluating the subchronic adverse effects of Counter 15FC (a terbufos -based pesticide formulation) in adult male Wistar albino rats, focusing on neurological, liver, kidney and reproductive functions. Five groups of animals were administered either vehicle (Control) or Counter 15FC at doses 0.1 - 3 mg/kg body weight (bwt) for 9 weeks. All surviving animals were sacrificed at the end of the treatment period, and their liver, kidneys and reproductive organs weighed. Testosterone levels, acetylcholinesterase (AChE) and butyrylcholinesterase (BuChE) activities, biomarkers for liver function (alanine transaminase and aspartate transaminase activities), kidney function (creatinine and uric acid) and total antioxidant capacity were assessed in serum. Oxidative stress markers (thiobarbituric acid reactive species, reduced glutathione levels and catalase activity) were determined in testicular and liver homogenates. Counter 15 FC at the dose of 3 mg/kg bwt induced tremors, seizures and death of 4 animals after 6 days of experiment. The pesticide formulation at 1 mg/kg bwt inhibited AChE and BuChE after 9 weeks. Moreover, the pesticide doses 0.1 and 0.3 mg/kg bwt inhibited testicular catalase activity, while other parameters investigated remained unchanged. Overall, results from this study suggest that exposure to Counter 15 FC can be fatal. The pesticide toxicity occurs at least in part through inhibition of cholinesterase and catalase activities in nervous system and testis, respectively.


1. FAO., 2003. International Code of Conduct on the Distribution and Use of Pesticides (Revised Version), adopted by the Hundred and Twenty-third Session of the FAO Council in November 2002.  Food and Agriculture Organization of the United Nations (FAO), Rome, 2003, 36P. Available at: (accessed 09 April 2020).
2. Arfat Y., Mahmood N., Tahir M.U., Rashid M., Anjum S., Zhao F., Li D.J., Sun Y.L., Hu L., Zhihao C., Yin C., Shang P., Qian A.R., 2014. Effect of imidacloprid on hepatotoxicity and nephrotoxicity in male albino mice. Toxicol Rep. 1, 554-561.
3. Kim K.H., Kabir E., Jahan S.A. 2017. Review: Exposure to pesticides and the associated human health effects. Sci Total Environ. 575, 525-553.
4. Nantia E.A., Kada A.S., Manfo F.P.T., Tangu N., Mbifung K.M., Desire M.H., Kenfack A., 2018. Parastar insecticide induced changes in reproductive parameters and testicular oxidative stress biomarkers in Wistar male rats. Toxicol Ind Health. 34,499-506.
5. Manfo F.P.T., Suh C.F., Nantia E.A., Moundipa P.F., Cho-Ngwa F., 2021. Occupational use of agrochemicals results into inhibited cholinesterase activity and altered reproductive hormone levels in male farmers from Buea, Cameroon. Toxicol Research. 10(2), 232–248.
6. Cambers J.E., Carr R.L., Boone J.S., Chambers H.W., 2001. The Metabolism of Oragnophosphorus Insecticides. In: Krieger RI (Ed), Handbook of Pesticide Toxicology, 2nd Ed Vol. 2. Academic Press; 2001. pp. 919–927. 
7. USEPA., 2001. Terbufos IRED Facts. EPA 738-F-01-015
October 2001. Available at: (accessed 12 March 2021).
8. Bonner M.R., Williams B.A., Rusiecki J.A., Blair A., Beane Freeman L.E., Hoppin J.A., Dosemeci M., Lubin J., Sandler D.P., Alavanja M.C., 2010. Occupational exposure to terbufos and the incidence of cancer in the Agricultural Health Study. Cancer Causes Control. 21, 871-7.
9. Gupta R.C., Milatovic D., 2014. Chapter 23 – Insecticides. In: Gupta R (Ed), Biomarkers in Toxicology, pp389-407.
10. WHO., 2005. The World Health Organisation (WHO) recommended classification of pesticides by hazard and guidelines to classification: 2004. Geneva: International Programme on Chemical Safety. © World Health Organization 2005, Available at: (accessed 09 April 2020).
11. Liang Y., Tong F., Zhang L., Li W., Huang W., Zhou Y., 2018. Fatal poisoning by terbufos following occupational exposure. Clinical Toxicology. 56, 140-142.
12. FAO/WHO., 2003. Terbufos, Joint Meeting on Pesticide Residues (JMPR). First draft prepared by K. L. Hamernik, Office of Science Coordination and Policy, United States Environmental Protection Agency, Washington DC, USA. In: FAO Plant Production and Protection Paper, 176, 2004 - Pesticide residues in food - 2003. Report of the Joint Meeting of the FAO Panel of Experts on Pesticide Residues in Food and the Environment and the WHO Core Assessment Group; Tox Monograph : TERBUFOS - JMPR 2003.pdf., pp333-385, 2003, (Available at: (accessed 05 January 2020).
13. Mitra A., Maitra S.K., 2018. Reproductive Toxicity of Organophosphate Pesticides. Ann Clin Toxicol 1: 1004 Available at: (accessed 09 April 2020).
14. Mesnage R., Defarge N., Spiroux de Vendômois J., Séralini G.E., 2014. Major pesticides are more toxic to human cells than their declared active principles. Biomed Res Int. 2014, 179691.
15. Jonca J., Zuk M., Wasag B., Janaszak-Jasiecka A., Lewandowski K., Wielgomas B., Waleron K., Jasiecki J., 2015. New insights into butyrylcholinesterase assay, serum dilution factor as crucial parameter. PLoS One. 10(10), e0139480.
16. Manfo F.P.T., Mboe S.A., Nantia E.A., Ngoula F., Telefo P.B., Moundipa P.F., Cho-Ngwa F., 2019. Evaluation of the effects of agro pesticides exposure on the liver and kidney function in farmers from Buea, Cameroon. Journal of Toxicology, Article ID 2305764,
17. Benzie I.F.F., Strain J.J., 1996. The ferric reducing ability of plasma (FRAP) as a measure of “antioxidant power”: The FRAP assay. Anal Biochem. 239, 70-76.
18. Misra H.P. Fridovich I., 1972. The generation of superoxide radical during the autoxidation of heamoglobin. J Biol Chem. 247, 6960-6962.
19. Wilbur K.M., Bembeim F., Shapiro O.W., 1949. The thiobarbituric acid reagent as a test for the oxidation of unsaturated fatty acids by various agents. Arch Biochem Biophys. 24,305-313.
20. Ellman G.L. 1959. Tissue sulfhydryl groups. Arch Biochem Biophys.82, 70-77.
21. Gornall A.G., Bardwill G.S., David M.M., 1949. Determination of serum protein by means of biuret reactions. J Biol Chem. 177, 751-766.
22. Weiner M., Nemec M., Sheets L., Sargent D., Breckenridge C., 2009. Comparative functional observational battery study of twelve commercial pyrethroid insecticides in male rats following acute oral exposure. NeuroToxicology. 30,1-16.
23. Lalley P.M., Rossi G.V., Baker W.W., 1970. Analysis of local cholinergic tremor mechanisms following selective neurochemical lesions. Experimental Neurology. 27, 258-275.
24. Li J.T., Sheng S.J., Du X.L., 1999. Metabolism of Terbufos in Rat Liver. J Occup Health. 41(2), 62-68.
25. Masson P., Lockridge O., 2010. Butyrylcholinesterase for protection from organophosphorus poisons: catalytic complexities and hysteretic behavior. Arch Biochem Biophys. 494(2), 107-20.
26. Colović M.B., Krstić D.Z., Lazarević-Pašti T.D., Bondžić A.M., Vasić V.M., 2013. Acetylcholinesterase inhibitors: pharmacology and toxicology. Curr Neuropharmacol. 11, 315-35.
27. Szelényi J.G., Bartha E., Hollán S.R., 1982. Acetylcholinesterase activity of lymphocytes: an enzyme characteristic of T-cells. Br J Haematol. 50(2), 241-245.
28. Rotundo R.L., 2017. Biogenesis, assembly and trafficking of acetylcholinesterase. J Neurochem. 142,52-58.
29. Reid G.A., Chilukuri N., Darvesh S., 2013. Butyrylcholinesterase and the cholinergic system. Neuroscience. 234, 53-68.
30. Kim,J.R., Kim H.J., Kwon O.S., 2005. Acetylcholinesterase and neuropathy target esterase activity in female and male rats exposed to pesticide terbufos. Environ Toxicol Pharmacol. 20,149-56.
31. Lu S., Liu S., Cui J., Liu X., Zhao C., Fan L., Yin S., Hu H., 2019. Combination of Patulin and Chlorpyrifos Synergistically Induces Hepatotoxicity via Inhibition of Catalase Activity and Generation of Reactive Oxygen Species. J Agric Food Chem. 67, 11474-11480.
32. Nandi A., Yan L.J., Jana C.K., Das N., 2019. Role of Catalase in Oxidative Stress- and Age-Associated Degenerative Diseases. Oxid Med Cell Longev, Article ID 9613090,
33. Mora-Esteves C., Shin D., 2013. Nutrient supplementation: improving male fertility fourfold. Semin Reprod Med. 31, 293-300.
34. Hung J.H., Chen C.Y., Omar H.A., Huang K.Y., Tsao C.C., Chiu C.C., Chen Y.L., Chen P.H., Teng Y.N., 2016. Reactive oxygen species mediate Terbufos-induced apoptosis in mouse testicular cell lines via the modulation of cell cycle and pro-apoptotic proteins. Environ Toxicol. 31, 1888-1898.
35. Vandenberg L.N., Colborn T., Hayes T.B., Heindel J.J., Jacobs D.R. Jr., Lee D.H., Shioda T., Soto A.M., vom Saal F.S., Welshons W.V., Zoeller R.T., Myers J.P., 2012. Hormones and endocrine-disrupting chemicals: low-dose effects and nonmonotonic dose responses. Endocr Rev. 33(3), 378-455.
36. Karami-Mohajeri S., Ahmadipour A., Rahimi H., Abdollahi M., 2017. Adverse effects of OPs on the liver: a brief research summary. Arh Hig Rada Toksikol. 68, 261-275
37. Argawal A., Virk G., Ong C., Du Plessis S., 2014. Effect of oxidative stress on male reproduction. World J Mens Health 32, 1-17.
38. Pearson J.N., Patel M., 2016. The role of oxidative stress in organophosphate and nerve agent toxicity. Ann N Y Acad Sci. 1378, 17-24.
39. Shah M.D., Iqbal M., 2010. Diazinon-induced oxidative stress and renal dysfunction in rats. Food Chem Toxicol. 48, 3345-3353.
40. Uzun F.G., Kalender Y., 2011. Protective effect of vitamin C and E on malathion induced nephrotoxicity in male rats. Gazi University Journal of Science. 24, 193-201.
41. Ojha A., Yaduvanshi K., Pant S.C., Lomash V., Srivastava N., 2013. Evaluation of DNA damage and cytotoxicity induced by three commonly used organophosphate pesticides individually and in mixture, in rat tissues. Environ Toxicol. 28, 543-552.
42. Murray P.T., Mehta R.L., Shaw A., Ronco C., Endre Z., Kellum J.A., Chawla L.S., Cruz D., Ince C., Okusa M.D., ADQI 10 workgroup., 2014. Potential use of biomarkers in acute kidney injury: report and summary of recommendations from the 10th Acute Dialysis Quality Initiative consensus conference. Kidney Int
Volume 11, Issue 2
May 2021
Pages 169-180
  • Receive Date: 01 July 2020
  • Revise Date: 19 March 2021
  • Accept Date: 24 April 2021
  • First Publish Date: 26 April 2021