Pesticide Poisoning of Farm Workers: Implications of Blood Test Results from Vietnam

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1 Pesticide Poisoning of Farm Workers: Implications of Blood Test Results from Vietnam Susmita Dasgupta, Craig Meisner, David Wheeler, Nhan Thi Lam, Khuc Xuyen The World Bank and The National Institute of Occupational and Environmental Health, Vietnam

2 Pesticide consumption (metric tons) in Vietnam 45,000 40,000 35,000 30,000 Metric tons 25,000 20,000 15,000 10,000 5, Source: FAO, 2004 Pesticide consumption has more than doubled in the past decade

3 Alarming Composition/Application of Pesticides In 2000, a nation-wide survey by PPD found: 2,500kgof banned pesticides (Methamidophos, DDT and others). 4,753 litres and 5,645 kg of illegally imported/ counterfeit pesticides. In 2000, another survey in the South found: 96.6% of the farmers over-use pesticides 95% of the farmers pour residual spray into canals/ ditches/ re-apply it on other plants/ overapply it to the same crop to get rid of it.

4 Vietnam has limited secondary data on Health Effects of pesticides Questions of Interest: 1. What is the incidence of pesticide intoxication? 2. Are self-reported data good indicators of actual intoxication? 3. What are the determinants of pesticide intoxication? Methodology: 1. Survey of Rice Farmers (pesticide applicators) in Mekong delta. 2. Clinical Exam 3. Blood Test

5 Application of pesticides: survey evidence Class No. of applications Pesticide amount (kg a.i.) Intensity (kg a.i./appl.) Summer- Autumn Autumn- Winter Summer- Autumn Autumn- Winter Summer- Autumn Autumn- Winter 2-dimethylaminopropane-1,3-dithiol Chloroacetamide Dithiolane DMI: triazole Carbamate Organophosphate MBI: reductase Multi-site: inorganic Phenoxycarboxylic acid Benzimidazole Dicarboximide Pyrethroid Phosphorothiolate Antibiotic Multi-site: alkylenebis (dithiocarbamate) Neonicotinoid Glycine derivative Fiprole Unknown Pyrimidinyloxybenzoic Aryloxyphenoxypropionate Cyclodiene Quinolinecarboxylic acid Sulfonylurea Multi-site: phthalimide Non-ester pyrethroid Benzimidazole precursor Hexopyranosyl antibiotic Total * A total number of 1252 applications by 190 farmers. Chemical class was derived from the British Crop Protection Council e-pesticide Manual, Thirteenth Edition (BCPC, 2003).

6 Health Effects of Organophosphates and Carbamates cited in Medical Literature Acute: Mild headaches Flu-like symptoms Skin rashes Blurred vision Other neurological disorders Chronic: Cardiopulmonary problems Neurological and hematological symptoms Adverse dermal effects

7 Blood Test for the Detection of Acute and Chronic Pesticide Poisoning Cholinesterase Enzyme (AchE)Test: (poisoning from organophosphates and carbamates) Low Acute Poisoning: Reduction of numerical value of AchE in red cells and in plasma >25% High Acute Poisoning: Reduction of numerical value of AchE in red cells and in plasma >33% Chronic Poisoning: Reduction of numerical value of AchE in red cells >66%

8 Specific Health Effects found in the Survey Percentage Skin irritation Headache Other problems Eye irritation Dizziness Shortness of breath Vomiting Fever Diarrhea Convulsions % responding 'Yes' 98%of the farmers in the survey reported health problems 88%of the respondents experienced multiple health effects, with the maximum number of ailments as nine

9 Blood (Cholinesterase Enzyme) Test Results Normal 65% Poisoning 35% Low acute poisoning 1 9% High acute posioning 2 5% Chronic poisoning 3 21%

10 Self-reported symptoms are not reliable indicators of actual pesticide poisoning (Correlation between each individual symptom and blood test results were conducted. The highest correlation found was 0.17)

11 Determinants of Cholinesterase Enzyme Inhibition: Regression Analysis Model 1 Model 2 Variable Coefficient Coefficient PESTAMT ** (-2.09) ** (-2.24) PWHOIab 0.039*** (2.51) 0.030** (2.08) PWHOII (0.46) PWHOIII (1.19) PWHOU (0.90) PTRAIN (1.22) NPROTECT * (-1.86) * (-1.91) IPMD (0.19) An Giang (-0.33) Can Tho ** (-2.49) Long An (-1.36) Tien Giang *** (-2.58) ** (-2.39) ** (-2.41) Observations * - significant at the 1% level; ** - significant at the 5% level; *** - significant at the 10% level

12 Determinants of Cholinesterase Enzyme Inhibition: Regression Results Farmers applying more hazardous pesticides (WHO Ia & Ib) are more likely to suffer Incidence of pesticide poisoning can be significantly reduced by suitable averting behavior Pesticide poisoning in Vietnam revealed strong provincial pattern. This raises the concern that the environment in certain regions may have been contaminated from prolonged exposure to toxic pesticides

13 Summary and Conclusions Health effects of organophosphates and carbamates is serious in Mekong Delta, Vietnam Self-reported symptoms have very weak associations with actual poisoning Suitable averting behavior while handling pesticides should be advocated Significant provincial differences in poisoning incidence implies that pesticide contamination may be pervasive in certain areas Tests of pesticide residues in surface/ground water and soil is necessary

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