Occupational pesticide exposure among Kenyan agricultural workers : an epidemiological and public health perspective

G.J.A. Ohayo - Mitoko

    Research output: Thesisinternal PhD, WU


    <br/>This study was part of the Kenyan component of a multi-centre epidemiologic survey, the East African Pesticides Project. The general objective was to assess the health hazards posed by pesticide handling, storage and use in agricultural estates and small farms in selected rural agricultural communities in Kenya where cotton, tobacco, flowers and other horticultural crops are grown, with a view to developing strategies for the prevention and control of pesticide poisoning. 666 agricultural workers, 120 agricultural extension workers and 108 health care workers from Naivasha, Wundanyi, Homabay and Migori comprised the study population. It was found that the 370 formulations registered for use in Kenya by the Pest Products Control Board (PCPB), represented 217 active ingredients. About 22% of the volume imported were highly hazardous, 20%, moderately hazardous, 45% slightly hazardous and the rest, unclassified. Acetylcholinesterase inhibition occurred in agricultural workers ( 390 exposed; 276 unexposed) as a result of exposure to organophosphate and carbamate pesticides. Acetylcholinesterase levels of 29.6% of exposed individuals were depressed to values below 60% of baseline. Workers from Naivasha had the largest inhibition (36%), followed by Homabay (35%), and Wundanyi (33%); workers from Migori had by far, the least inhibition (26%). Empirical modelling techniques were used to identify and quantify factors affecting exposure to cholinesterase-inhibiting pesticides. The models were adequate as they explained 57-70% of the observed variability in acetylcholinesterase. There was no significant difference in personal hygiene practices between areas. Access to a washing and bathing facility had a positive effect while washing hands and bathing was found to be more reactive than proactive. Spraying had a more profound effect on cholinesterase levels than mixing of pesticides. It has also been shown that workers who sprayed less hazardous pesticides had less inhibition than their counterparts who sprayed more toxic pesticides. However, hardly any variability existed in factors such as personal protective devices and hygienic behaviour within areas, thereby limiting the power of the models to detect the effects of these potential factors affecting exposure. The prevalence of symptoms in this population was described in order to relate levels of inhibition to reported symptoms and to evaluate at which inhibition levels symptoms become elevated. The prevalence of symptoms was found to be higher during the high exposure period than during the low exposure period in the exposed subjects. The presence of a relationship between acetylcholinesterase inhibition, acetylcholinesterase level and respiratory, eye and central nervous system symptoms was established. Increased symptom prevalence was observed at acetylcholinesterase levels which are generally considered as non-adverse. The knowledge, perceptious, observed and reported practices were assessed for the population of agricultural workers. Knowledge was found to be low with regard to safe use of pesticides. For instance the most important route of occupational exposure to pesticides. Practices such as storage, mixing and application were found to be generally poor. Personal hygiene practices were good but the use of personal protective devices was low especially among farmers in Homabay and Migori. The knowledge, perceptions and practices of agricultural extension workers was assessed with respect to safe handling of pesticides. About one third of the extension workers did not know the pesticide operations responsible for poisoning. All the extension workers reported that they were involved with advising on the use of pesticides but only 80% gave advise on safe use. About two thirds of the extension workers felt that pesticides poisoning was a minor problem. They emphasized following of instructions, use of personal protective clothing and devices as well as personal hygiene to prevent poisoning. Knowledge, perceptions and practices of health care workers were also assessed with respect to diagnosis, management and prevention of pesticide poisoning. Only about one fifth of the health care workers thought pesticide poisoning was a major problem in the community. Most of the health care workers were able to provide information on the health aspects of pesticides but less than ten percent of this information was directed at the farmers. Diagnosis of poisoning was found to be difficult with only one third of the health care workers reporting that they had seen at least one case of pesticide poisoning in the duration of time that they worked in this agricultural area. Almost all health care workers reported that they would like information and training as well as drugs and antidotes for the management and treatment of poisoning. Lack of knowledge, poor perceptions and practices at all levels as well as the availability and use of the more toxic pesticides were found to be major factors influencing pesticide poisoning. It is necessary to urgently initiate interventions to address the gaps found. The results of this study will facilitate the development of effective multi-faceted strategies for the management, prevention and control of occupational pesticide exposure in Kenya and other developing countries.
    Original languageEnglish
    QualificationDoctor of Philosophy
    Awarding Institution
    • Boleij, J.S.M., Promotor
    • Kromhout, H., Promotor
    • Koelen, Maria, Promotor
    Award date28 Oct 1997
    Place of PublicationS.l.
    Print ISBNs9789054857747
    Publication statusPublished - 1997


    • occupational disorders
    • toxic substances
    • toxicology
    • plant protection
    • pesticides
    • adverse effects
    • vertebrates
    • man
    • kenya

    Fingerprint Dive into the research topics of 'Occupational pesticide exposure among Kenyan agricultural workers : an epidemiological and public health perspective'. Together they form a unique fingerprint.

    Cite this