Case fatality as an indicator for the human toxicity of pesticides - a systematic review on the availability and variability of severity indicators of pesticide poisoning
Objective: To investigate if case fatality and other indicators of severity of human pesticide poisonings can be used to prioritize pesticides of public health concern. To study the heterogeneity of data across countries, cause of poisonings, and treatment facilities. Methods: We searched literature databases as well as the internet for studies on case-fatality and severity scores of pesticide poisoning. Studies published between 1990 and 2014 providing information on active ingredients in pesticides or chemical groups of active ingredients were included. The variability of case-fatality-ratios was analyzed by computing the coefficient of variation as the ratio of the standard deviation to the mean. Findings: We identified 145 studies of which 67 could be included after assessment. Case-fatality-ratio (CFR) on 68 active ingredients and additionally on 13 groups of active ingredients were reported from 20 countries. Mean CFR for group of pesticides is 12 %, for single pesticides 15 %. Of those 12 active ingredients with a CFR above 20 % only two are WHO-classified as 'extremely hazardous' or 'highly hazardous', respectively. Two of seven pesticides considered 'unlikely to present hazard in normal use' show CFR above 20 %. The variability of reported case fatality was rather low. Conclusion: Although human pesticide poisoning is a serious public health problem an unexpected small number of publications report on the clinical outcomes. However, CFR of acute human pesticide poisoning are available for several groups of pesticides as well as for active ingredients and show little variability. Therefore the CFR might be utilized to prioritize highly hazardous pesticides especially since there is limited correspondence between the animal-test-based hazard classification and the human CFR of the respective pesticide. Reporting of available poisoning data should be improved, human case-fatality data are a reasonable tool to be included systematically in pesticide registration and regulation.