Dalvie MA, White N, Raine R, Myers JE, London L, Thompson M, and Christiani DC, Long term respiratory health effects of the herbicide, paraquat, among workers in the Western Cape, Occupational and Environmental Medicine 56(6), 391-396, 1999

A study in South Africa was carried out with 62 herbicide sprayers (fruit farmers) who had different levels of previous exposure to paraquat. For the individual workers the cumulative paraquat exposure was assessed in interviews and from expert knowledge, and data on respiratory symptoms was collected with the aid of a standard questionnaire followed by a medical examination. The lung function (forced expiratory volume in 1 second, forced vital capacity) and transfer of carbon monoxide (CO) were measured and compared with refer-ence values of the European Community of Coal and Steel (ECCS). Radiographs of the chest were taken to exclude cases of tuberculosis. Lung capacities were found to be 10-15% lower than EECS reference values. Respiratory symptoms (regular coughing, expec-toration, breathlessness) were not significantly related to exposure to paraquat, while de-saturation of arterial oxygen during exercise (difference during resting and maximum exer-cise level) was significantly related to long-term paraquat exposure. Although they contrib-uted to a small proportion of variance, weight, intensity of exposure to paraquat (days per year) and the cumulative exposure to paraquat (total of days) were signignificant factors for oxygen desaturation (p< 0.05) in a regression model. Excluding workers from the sam-ple who reported the use of other herbicides besides paraquat did not weaken the dose-dependent association. This effect was independent of recent paraquat exposure and in 18.8% of workers the level of desaturation was over 5%, which is regarded as clinically notable.