Investigation of ditidocarbamate fungicides and ethylenetidourea metabolite residues in some vegetables from Kiriny aga and Nairobi counties
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Date
2014-07-24
Authors
Karanja, Elias Kiura
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Abstract
Vegetables are a major source of minerals, proteins, energy and roughage. Some vegetables such
as tomato and sweet pepper can be eaten raw or cooked. Pests and diseases that destroy
vegetables are controlled using pesticides among which are fungicides such as dithiocarbamates
(D'I'Csj.These chemicals are toxic to animals including man at high concentrations and injurious
to the environment. DTCs are commonly used in different combinations in Kenya and one of
their metabolites ethylenthiourea (ETU) which has a long residual time of between five to ten
weeks is believed to be carcinogenic. Cooking degrades DTCs to metabolites such as ETU while
proper cleaning or processing can remove the residues considerably. There is therefore a need to
investigate the levels of these pesticides and their metabolite in food. This study proposes to
determine the residue levels of DTCs zinc propylene bisdithiocarbamate (propineb), zinc
manganese ethylenebisdithiocarbamate (mancozeb) and the metabolite ETU in tomato
(Lycopersicon esculentum) and sweet pepper (Capsicum annum l). The samples will be obtained
from some markets in Kirinyaga and Nairobi Counties during dry and wet seasons. The study
will also determine the effect of different washing methods and temperature on the residues of
samples obtained from an Experimental garden. Samples will be analyzed when cooked at
different temperatures and when washed with water or sodium hypochlorite to note variation and
levels of DTCs and ETU in processed food. The pesticides will be extracted by solvent
extraction (liquid-liquid extraction) using acetonitrile"-dichloromethane-chloroform mixture in
the ratio of 1:1:1 and analyzed using HPLC. Residue levels will be compared with the acceptable
daily intake (ADI) and maximum residue limits (MRLs) allowed by WHOIFAO and ED. The
results will inform relevant authorities for action if necessary with an expected impact of a more
cancer free population. Results will be used to educate farmers, vendors and consumers through
publications and seminars the best methods of handling the said produce to ameliorate the
effects.