Assessment of the Levels and Potential Health Risk Posed by Selected Organophosphate Pesticide Residues in Vegetable Farms in Manzini Region, Eswatini
International Journal of Bioorganic Chemistry
Volume 4, Issue 1, June 2019, Pages: 53-63
Received: Feb. 18, 2019; Accepted: Mar. 30, 2019; Published: May 6, 2019
Views 775      Downloads 125
Gabriel Chewe Bwembya, Department of Chemistry, Faculty of Science and Engineering, University of Eswatini, Kwaluseni, Eswatini
Paul Junior, Department of Chemistry, Faculty of Science and Engineering, University of Eswatini, Kwaluseni, Eswatini
Justice Mandla Thwala, Department of Chemistry, Faculty of Science and Engineering, University of Eswatini, Kwaluseni, Eswatini
Sipho Samuel Mamba, Department of Chemistry, Faculty of Science and Engineering, University of Eswatini, Kwaluseni, Eswatini
Tesfamariam Yosief Debessai, Department of Chemistry, Faculty of Science and Engineering, University of Eswatini, Kwaluseni, Eswatini
Nomfundo Dlamini, Department of Food Science, Nutrition and Technology, Faculty of Agriculture, University of Nairobi, Kabete, Kenya
Article Tools
Follow on us
The study investigated qualitatively and quantitatively the presence of organophosphate pesticide (OPP) residues in cabbages, tomatoes and soil from vegetable gardens of Manzini region and assessed the health risk to consumers. Samples were analysed using QuEChERS extraction technique and GC-ECD. Mean recoveries of the pesticides range from 70.61% to 103.76%. Among 26 samples of cabbages analysed, 8 samples (30.77%) contained residues of dichlorvos with a mean concentration of 2.889 ± 0.617 mg/kg, 8 samples (30.77%) contained residues of dimethoate with mean concentration of 2.898 ± 0.894 mg/kg while 5 samples (19.23%) contained both dichlorvos and dimethoate. The highest concentration of dichlorvos of 5.460 ± 0.911 mg/kg was found in Ngwempisi cabbages while the lowest concentration of 0.415 mg/kg was in Mgazini cabbages. The highest amount of dimethoate of 13.150 ± 3.246 mg/kg was in Matfunjwa cabbages while the lowest amount of dimethoate of 0.106 ± 0.187 mg/kg was in Boyane cabbages. All the contaminated cabbages had residue levels above the Codex (FAO/WHO) and EU MRLs. None of the 15 samples of tomatoes was found to be contaminated with organophosphate pesticides. Out of 41 samples of soil, chlorpyrifos was detected in only 3 samples (7.32%) with mean concentration of 1.145 ± 0.136 mg/kg. The highest amount of 2.778 ± 0.134 mg/kg was found in soil from Buoyane. The health risk estimate also demonstrated that the levels of pesticides residues in cabbages pose health threat to consumers. The results of this study provide a database on the levels of organophosphate pesticide residues in vegetables in the Manzini region to the Ministries of Agriculture and Health. This will help introduce safer pesticide management practices. It will also bring awareness to the general public on the dangers of OPPs to human health and environment.
Health-Risk, GC-ECD, Organophosphate Pesticides, QuEChERS, Vegetables
To cite this article
Gabriel Chewe Bwembya, Paul Junior, Justice Mandla Thwala, Sipho Samuel Mamba, Tesfamariam Yosief Debessai, Nomfundo Dlamini, Assessment of the Levels and Potential Health Risk Posed by Selected Organophosphate Pesticide Residues in Vegetable Farms in Manzini Region, Eswatini, International Journal of Bioorganic Chemistry. Vol. 4, No. 1, 2019, pp. 53-63. doi: 10.11648/j.ijbc.20190401.18
Copyright © 2019 Authors retain the copyright of this article.
This article is an open access article distributed under the Creative Commons Attribution License ( which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
Sharma, D. R., Thapa, R. B., Manandhar, H. K., Shrestha, S. M. and Pradhan, S. B. (2012). Use of pesticides in Nepal and the impacts on human health and environment. Journal of Agriculture and Environment, 13: 67-68.
Steven, G. (2014). “Organophosphates”. Accessed through Retrieved on 7 June 2017.
Jamal, G. A., Hansen, S., Pilkington, A., Buchanan, D., Gillham, R. A. and Abdel-Azis, M. (2002). A clinical neurological, neurophysiological, and neuropsychological study of sheep farmers and dippers exposed to organophosphate pesticides. Journal of Occupational and Environmental Medicine, 59: 434-441.
Eddleston, M., Buckley, N. A., Eyer, P. and Dawson, A. H. (2008). Management of acute organophosphorus pesticide poisoning. Lancet, 371(9612): 597-607.
World Bank (2008). World Development Report on Agriculture for Development. Retrieved from
Dementi, B. (1994). ‘Ocular Effects of Organophosphates: A Historical Perspective of Saku Disease’. Journal of Applied Toxicology, 14(2): 119-129.
Andrew, G. R. (2002). Pesticide residue analysis and its relationship to hazard characterization and intake estimation. Pest Management Science, (58): 1073-1082.
Akan, J. C., Jafiya, L., Mohammed, Z. and Abdulrahman, F. I. (2013). Organophosphorus pesticide residues in vegetables and soil samples from Alau dam and Gongulong agricultural areas, Borno State, Nigeria. International Journal of Environmental Monitoring and Analysis, 1(2): 58-64.
Frederick, A. A. (2011). Assessment of pesticide residues in vegetables at the Farm Gate: Cabbage (Brassica oleracea) Cultivation in Cape Coast, Ghana. Research Journal of Environmental Toxicology, 5: 180-202.
Sekhon, M. K. and Kaur, M. (2004). Role of small farmers in diversification of Punjab agriculture with vegetables. Indian Journal of Agricultural Marketing, 18(1): 80-88.
Thompson, C. F. (2012). Swaziland business year book. Mbabane-Swaziland: Christina Forsyth- Thompson.
NAMBoard (2009). Annual Report for National Agricultural Marketing Board, Manzini, Swaziland.
FAOSTAT (2016). World: Vegetable Total Production, Mbabane, Swaziland.
Frederick, M. and Fishel, K. (2005). Pesticide information office; Florida cooperative extension service, Institute of Food and Agricultural Sciences, University of Florida.
EU Pesticide Database. Available on$language=EN. Accessed on 13th February, 2018.
Codex Alimentarius International Food Standards. Food and Agriculture Organisation of United Nations and World Health Organisation. Accessed on 8th February, 2018.
Singh, A. S., Mhlanga, N. P. and Kibirige, D. (2017). Gender contribution on profitability of vegetable production in the rural Manzini region of Swaziland. International Journal of Research in Management, Economics and Commerce, 7(6): 90-98.
European commission (EC). Establishing community methods of sampling for the official control of Pesticide Residues in and on products of plant and animal origin and Repealing Directive. OJEUL 2002, 187, 30-43.
Anastassiades, M., Lehotay, S. J., Štajnbaher, D. and Schenck, F. J. (2003). Fast and easy multiresidue method employing acetonitrile extraction/partitioning and “dispersive solid phase extraction” for the determination of pesticide residues in produce. International Journal of Association of Official Analytical Chemists, 86: 412-431.
Prodhan, M. D. H., Papadakis, E. N. and Mourkidou, E. P. (2015). Determination of multiple pesticide residues in eggplant with liquid chromatography-mass spectrometry. Food Analytical Methods, 8: 229–235.
U.S. EPA. (1996). Integrated risk information system. United States Environmental Protection Agency. Office of Health and Environmental Assessment, Washington, D. C.
Donkor, A., Osei-Fosu, P., Nyarko, S., Kingsford-Adaboh, R. and Okyere, J. Y. A. (2015). Health Risk Assessment of Pesticide Residues via Dietary intake of cowpeas and Bambara beans among adults in Accra Metropolis, Ghana. Research Journal of Chemical and Environmental Science, 3 (1): 10-18.
Bempah, C. K., Donkor, A., Yeboah, P. O., Dubey, B. and Osei-Fosu, P. (2011). A Preliminary assessment of consumer’s exposure to organochlorine pesticides in fruits and vegetables and the potential health risk in Accra Metropolis, Ghana. Food Chemistry, 128(4): 1058-1065.
Chien, L. C., Hung T. C., Choang, K. Y. and Meng, P. J. (2002). Daily intake of TBT, Cu, Zn, Cd and As for fishermen in Taiwan. Science of the Total Environment, 285: 177–185.
Xaba, B. G. and Masuku, M. B. (2013). An analysis of the vegetable supply chain in Swaziland. Sustainable Agriculture Research; Vol. 2, No. 2. Published by Canadian Center of Science and Education.
Eurachem Guide (2014). The Fitness for Purpose of Analytical Methods – A Laboratory Guide to Method Validation and Related Topics, 2nd edition, Magnusson, B. and Ornemark, U. (eds.).
Gebremariam, S. Y., Beutel, M. W., Yonge, D. R., Flury, M. and Harsh, J. B. (2012). Adsorption and desorption of chlorpyrifos to soils and sediments. Reviews of Environmental Contamination and Toxicology, 215: 123-175.
Baride, M. V., Patil, S. N. and Golekar, R. (2015). Estimation of pesticide residues in soil, ground water, vegetables and fruits: A case study of Jalgaon district, Maharashtra (India). SRTM University’s Research Journal of Science. Spl. Vol. No. 1 (ISSN: 2227-8594).
Science Publishing Group
1 Rockefeller Plaza,
10th and 11th Floors,
New York, NY 10020
Tel: (001)347-983-5186