British Journal of Industrial Medicine 1992;49:615-619 Hazards of closed pesticide mixing and loading systems: the paradox of protective technology in the Third World Rob McConnell, Mario Cord6n, Douglas L Murray, Ralph Magnotti Abstract In studies in developing countries, closed sys- tems for mechanically mixing and loading hazardous pesticides have been shown to reduce exposure to workers. To evaluate the efficacy of closed systems in preventing worker exposure in the developing world, a cross sec- tional study was conducted at rural crop dust- ing airports in the cotton growing region of Nicaragua. Worker exposure was evaluated by measuring the activity of erythrocyte cholines- terase in the field with a new design battery operated colorimeter. The 10 mixer loaders at four airstrips with closed systems were com- pared with the 16 mixer loaders at four air- strips where pesticides were hand poured. Paradoxically, cholinesterase activity was 1 1 IU/ml blood (95% Cl 0-49-1-8) lower (inhibited) among workers in airstrips with closed sys- tems than among workers hand pouring insec- ticides, after adjusting for weight of organo- phosphates sprayed in the past 14 days, and for prior training in safe use of pesticides. Mixer loaders with prior training had cholinesterase activity 0-83 IU (95% Cl 0-301-4) higher than untrained workers, and the weight of organo- phosphates sprayed was also a statistically significant predictor in the model. Unfortun- ately, management viewed the closed systems primarily as a production to6l, rather than as a way to protect workers. Airstrips with closed Division of Occupational and Environmental Medicine, Mount Sinai Medical Centre, New York, New York and American Friends Service Committee, Philadelphia, Pennsylvania, USA R McConnell CARE Nicaragua, Managua, Nicaragua M Cordon Centre for Latin American Studies, Stanford University, Stanford, California, USA L Murray Division of Nephrology, University of Cincinnati School of Medicine, Cincinnati, Ohio, USA R Magnotti systems were able to apply an average of 3250 lb organophosphates per worker in the 14 days before the survey compared with 849 lb per worker in airstrips without closed systems. Only three of 10 mixer-loaders at airstrips with closed systems had received formal train- ing in safer use of pesticides. Because of shor- tage of personnel and transport, it was difficult for the responsible government agencies to train workers adequately and to enforce pes- ticide health and safety standards at multiple dispersed worksites. Mixing and loading pesticide concentrates into crop dusters is one of the jobs most highly exposed to pesticides. To protect mixer-loaders, California has passed pioneering regulations requiring the use of closed system mixing and loading equipment at crop dusting airstrips where workers are exposed to US Environmental Protection Agency category I (most hazardous) pesticides.' These systems, consisting of a pump and tubing, which automatically mix and load crop dusters without workers having contact with pesticides, are reported to decrease worker exposure by as much as 10 fold.2 Pesticide poisoning has long been a major public health problem on Nicaragua's northern Pacific coastal plain, comprising the departments of Leon and Chinandega, the country's principal cotton growing region.' The large cotton fields are traditionally sprayed with acutely toxic organophos- phate insecticides by crop dusting aeroplanes as many as 28 times in one season.7 In 1984 there were 27 poisonings reported in one year among a total of only 200-300 mixer-loaders in the region.6 As a result, starting in 1985 closed system mixing and loading units were installed in a pilot programme to prevent poisonings and to shift mixing and loading from the airports in the cities to smaller landing strips away from the major population centres. Closed systems were offered at nominal cost to all 50 licenced airstrips in the region, but had been purchased by only 21 at the time of this study. 615 group.bmj.com on June 20, 2017 - Published by http://oem.bmj.com/ Downloaded from