Acute pesticide poisonings in Nicaragua : underreporting, incidence and determinants

Abstract

Background: Acute pesticide poisonings (APP) are a public health problem in Nicaragua. The quality and coverage of APP´s register, the real incidence of APP, the main determinants, the economic cost of treating cases and the effectiveness of educational intervention are not well known.

Aim: The overall aim was to investigate the acute health impact of pesticide use and to discuss the possible effectiveness of preventive measures in Nicaragua. The specific aims were to calculate the proportion of APP cases officially registered, to estimate one year cumulative incidence of APP cases among population 15 years and older, to identify the main determinants related to APP among pesticide sprayers and to evaluate the impact of an integrated pest management (IPM) training intervention.

Methods: For studies 1, 2, and 3, data concerning pesticide exposure and health effects were assessed in a nationally representative survey of 3169 persons 15 years and older in year 2000. For study 1, to estimate the proportion of underreporting of APP cases, the cases reported at the official surveillance system were cross matched with the cases reported through the survey. In study 2, based on self reported cases we estimated the one year incidence rate and the number of expected cases of APP in the country. In study 3, after regression analysis, the main determinants for APP among agricultural sprayers were identified. Study 4 assessed the impact of a 2 years IPM training to reduce economic costs and acute adverse health effects among 1200 basic grain farmers comparing the group of trained farmers and a group of "control" farmers who did not receive training.

Results: Less than 5% of medically treated APP cases were reported to the official register. The one year APP incidence among general population was 2.3% (95%CI 1.7-2.8). The rate was higher among men, rural population and agricultural workers. More than 66,000 cases were estimated to occur yearly. The national incidence rate of APP among sprayers was extremely high, 8.3% (95% CI 5.8-10.8) and more than 34,000 cases were estimated to occur among pesticide sprayers, and representing 52% of all APP s estimated in year 2000. Although most of the cases were minor and moderate, the poisonings caused near 340,000 disability days. The causal agents for APP in 95% of cases were WHO Class I-II pesticides. The main determinants of APP among sprayers were: backpack pump leakage and incomplete or no use of personal protective equipment. Seventy seven percent of cases were caused by pesticides proposed to be banned or restricted in Central America. The IPM training prevented acute health effects and maintained productivity: after two years of training, the trained farmers used fewer pesticides, spent less money on pest control, made higher net returns, and suffered less exposure to cholinesterase-inhibiting pesticides compared to farmers who did not receive IPM training.

Conclusion: Underreport figures leads to an erroneous interpretation of acute pesticide health effects. There is a high APP incidence rate in the general population, but it is four times higher among sprayers, causing important loss of or productivity and important economic costs. IPM interventions were successful in prevent the occurrence of APP cases and economic losses. Traditional prevention and control measures are insufficient and structural changes, including pesticides banning and restriction, and change to IPM agriculture models, are needed to transform the underlying determinants.