Health Impact of Exposure to Pesticides in Agriculture in Tanzania

Abstract

AIM The aim of the study was to assess health hazards posed by pesticide handling, storage and use on agricultural estates and small farms in Tanzania where coffee, cotton, and other important crops are grown, with a view to developing strategies for the control of pesticide exposure and prevention of pesticide poisoning.

METHODS The target population was made up of farmers and other agricultural workers applying pesticides in coffee and cotton farms, as well as of non-agricultural control subjects, health care providers and extension workers in the same areas. -Background data were collected -Focused observations of target farms carried out, -Erythrocyte-acetylcholinesterase and organochlorine residue levels in blood samples determined and -Extensive interviews of agricultural workers, control subjects, health care providers, and extension service workers conducted.

RESULTS Background data A total of 104 pesticide chemical names and 179 trade names were compiled in Tanzania. Most of the pesticides were organophosphates, but carbamates, organochlorines, and pyrethroids were also represented. The pesticides included aldrin, endosulfan, DDT, dieldrin, camphechlor and lindane, which are either endocrine disruptors or persistent organic pollutants, and were banned or restricted in their countries of origin. Some were classified by World Health Organization as extremely or highly hazardous. For the period 1989/90, a total of 736 pesticide-poisoning cases were reported in the Tanzanian in-patient district hospital medical records with more women than men poisoned, however, the medical records were inadequate as they failed to show the cause or type of poisoning.

Focused observations More pesticide formulations were used on coffee compared with cotton, and in individually owned compared with cooperative farms. Coffee farms more often displayed unlabeled pesticide containers and missing instructions, while cotton pesticides were stored in bedrooms, near food, and near open fires, and pesticide leftovers were often present. Hazardous practices were more pronounced at the individually owned than the cooperative farms, with significant differences for pesticide storage areas, unlabeled and non-original containers.

Acute health effects Assessment of the extent and intensity of organophosphate exposure showed that erythrocyte acetylcholinesterase activities during spraying and non-spraying period were comparable. Similarly, the prevalence of cough, headache, abdominal pain, excessive sweating, nausea, diarrhoea, and vomiting did not differ significantly between spraying and non-spraying periods. There was no suggestion of decreased acetylcholinesterase activity in exposed subjects who complained of organophosphate­related symptoms compared to symptomless exposed subjects. Use of boots, head cover, face cover, and coverall was not significantly associated with acetylcholinesterase activity.

Pesticide knowledge and practices in health care and agricultural extension services. Eighty per cent of 104 health care providers interviewed reported to have seen pesticide poisoning, nine having seen two to four cases in the preceding three months. Pesticide poisoning was considered a major problem in the community by 63% of the health care providers, and a third thought that a number of poisoning cases remained unrecognised. Only one percent of the respondents could identify the group of pesticides predominantly used in the study areas. Only every fourth of the agricultural extension workers perceived pesticides as a major health problem in the community they served. Although high proportion claimed knowledge of first aid procedures in case of pesticide poisoning, many procedures described were not appropriate for the treatment of pesticide poisoning.

CONCLUSION Pesticide handling-practices on farms increased the risks of exposure of farm workers and their families to pesticides, thus undermining pesticide safety in many small farms in Tanzania. There was no strong indication for adverse effects of organophosphorus pesticides during the study period, either based on erythrocyte acetylcholinesterase or on symptoms. However, a great concern over potential long-term effects arising from the use of pesticides in these areas is eminent because pesticides suspected of long-term adverse effects are being used in hazardous work and living conditions. The extensionists were not aware of the health effects of pesticides and did not know what measures should be taken in case of poisoning. The failure of health care providers to distinguish the pesticide class, e.g. organophosphates and organochlorines, reflects a lack of understanding of the fundamental principles of diagnosis and treatment of pesticide poisoning, and may have a great impact on the prognosis. It also undermines the medical recording system especially for pesticide poisoning incidences. Therefore, pesticide exposures need to be reduced. Health care provides and extensionists need empowerment for prevention and treatment of adverse health effects.

AIM The aim of the study was to assess health hazards posed by pesticide handling, storage and use on agricultural estates and small farms in Tanzania where coffee, cotton, and other important crops are grown, with a view to developing strategies for the control of pesticide exposure and prevention of pesticide poisoning.

METHODS The target population was made up of farmers and other agricultural workers applying pesticides in coffee and cotton farms, as well as of non-agricultural control subjects, health care providers and extension workers in the same areas. -Background data were collected -Focused observations of target farms carried out, -Erythrocyte-acetylcholinesterase and organochlorine residue levels in blood samples determined and -Extensive interviews of agricultural workers, control subjects, health care providers, and extension service workers conducted.

RESULTS Background data A total of 104 pesticide chemical names and 179 trade names were compiled in Tanzania. Most of the pesticides were organophosphates, but carbamates, organochlorines, and pyrethroids were also represented. The pesticides included aldrin, endosulfan, DDT, dieldrin, camphechlor and lindane, which are either endocrine disruptors or persistent organic pollutants, and were banned or restricted in their countries of origin. Some were classified by World Health Organization as extremely or highly hazardous. For the period 1989/90, a total of 736 pesticide-poisoning cases were reported in the Tanzanian in-patient district hospital medical records with more women than men poisoned, however, the medical records were inadequate as they failed to show the cause or type of poisoning.

Focused observations More pesticide formulations were used on coffee compared with cotton, and in individually owned compared with cooperative farms. Coffee farms more often displayed unlabeled pesticide containers and missing instructions, while cotton pesticides were stored in bedrooms, near food, and near open fires, and pesticide leftovers were often present. Hazardous practices were more pronounced at the individually owned than the cooperative farms, with significant differences for pesticide storage areas, unlabeled and non-original containers.

Acute health effects Assessment of the extent and intensity of organophosphate exposure showed that erythrocyte acetylcholinesterase activities during spraying and non-spraying period were comparable. Similarly, the prevalence of cough, headache, abdominal pain, excessive sweating, nausea, diarrhoea, and vomiting did not differ significantly between spraying and non-spraying periods. There was no suggestion of decreased acetylcholinesterase activity in exposed subjects who complained of organophosphate­related symptoms compared to symptomless exposed subjects. Use of boots, head cover, face cover, and coverall was not significantly associated with acetylcholinesterase activity.

Pesticide knowledge and practices in health care and agricultural extension services. Eighty per cent of 104 health care providers interviewed reported to have seen pesticide poisoning, nine having seen two to four cases in the preceding three months. Pesticide poisoning was considered a major problem in the community by 63% of the health care providers, and a third thought that a number of poisoning cases remained unrecognised. Only one percent of the respondents could identify the group of pesticides predominantly used in the study areas. Only every fourth of the agricultural extension workers perceived pesticides as a major health problem in the community they served. Although high proportion claimed knowledge of first aid procedures in case of pesticide poisoning, many procedures described were not appropriate for the treatment of pesticide poisoning.

CONCLUSION Pesticide handling-practices on farms increased the risks of exposure of farm workers and their families to pesticides, thus undermining pesticide safety in many small farms in Tanzania. There was no strong indication for adverse effects of organophosphorus pesticides during the study period, either based on erythrocyte acetylcholinesterase or on symptoms. However, a great concern over potential long-term effects arising from the use of pesticides in these areas is eminent because pesticides suspected of long-term adverse effects are being used in hazardous work and living conditions. The extensionists were not aware of the health effects of pesticides and did not know what measures should be taken in case of poisoning. The failure of health care providers to distinguish the pesticide class, e.g. organophosphates and organochlorines, reflects a lack of understanding of the fundamental principles of diagnosis and treatment of pesticide poisoning, and may have a great impact on the prognosis. It also undermines the medical recording system especially for pesticide poisoning incidences. Therefore, pesticide exposures need to be reduced. Health care provides and extensionists need empowerment for prevention and treatment of adverse health effects.