Karanja E. K., Murungi J. I. & Nyambaka H.2025-04-112025-04-112023Karanja E. K., Murungi J. I. & Nyambaka H. (2023). Effect of Cooking Temperature and Cleaning Methods on Levels of Mancozeb and Ethylenethiourea in Tomato. In: Isutsa, D. K. (Ed.). Proceedings of the Chuka University 9th Annual International Research Conference held in Chuka University, Chuka, Kenya from 24th to 25th November, 2022. 460-459 pp.https://repository.chuka.ac.ke/handle/123456789/17674elkarunyaki@yahoo.comPests and diseases in vegetables are controlled using pesticides which include fungicides in the class of dithiocarbamates (DTCs) such as mancozeb which are injurious to the environment, animals and human at high concentrations. Cooking degrades DTCs to metabolites such as ethylenthiourea (ETU) known to be carcinogenic, while proper cleaning removes the residue considerably. This study determined the effect of temperatures achieved by cooking and cleaning methods on the residue levels of mancozeb and the metabolite ETU on tomato (Lycopersicon esculentum) sprayed with mancozeb. Samples were subjected to different temperature and cleaning treatments before extraction and method validation together with analysis by HPLC. The method of analysis had The R2 values (0.948- 0.999) and recoveries ranging from 91.26-95.89 %.The ETU residues rose from a mean of 9.43±0.03 mg/kg at 25℃ to a mean of 12.43±0.38mg/kg at 90℃, while mancozeb levels decreased from 5.23±0.02 mg/kg at 25℃ to non detectable levels at 60℃. The levels of ETU reduced from 46±0.71m/kg to 0.05± 0.00 mg/kg (99.9±0.00 %) when cleaned with sodium hypochlorite while, water alone reduced ETU to 0.27±0.08 mg/kg (99.4±0. 00%).Mancozeb levels in tomato cleaned with sodium hypochlorite, reduced by 95.2±0.00% while cleaning with water alone removed 16.3±0.64%. Cleaning with sodium hypochlorite showed a highly significant removal of fungicides compared to cleaning with water only. The results from this study indicates exposure of mancozeb and ETU in fresh and cooked tomato, hence a need for cleaning with chlorine and rinsing with water before consumption and a need for more alternatives of chemical cleaning.enMancozebEthylenethioureaTemperatureResidueTomatoCleaning.Article