Respiratory symptoms, spirometry and chronic occupational paraquat exposure

A cross-sectional study was conducted to evaluate the relationship between respiratory health and paraquat exposure.

The study population was selected from among workers at 15 Nicaraguan banana plantations which relied on paraquat for the control of weeds. All the workers were interviewed after they received their job assignment for the day of the survey, and all who reported never having applied paraquat and all who reported more than 2 years of cumulative exposure as applicators of paraquat with knapsack sprayers were invited for medical evaluation. One hundred and thirty-four exposed workers and 152 unexposed workers were administered a questionnaire interview asking about exposure and respiratory symptoms, and they underwent spirometric testing of forced expiratory volume in 1 s (FEV1.0) and forced vital capacity (FVC).

In the exposed group 53% reported having experienced a skin rash or burn resulting from paraquat exposure, 25% reported epistaxis, 58% nail damage, and 42% paraquat splashed in the eyes. There was a consistent dose-response relationship between intensity of exposure (as indicated by a history of skin rash or burn) and the prevalence of dyspnea. This relationship was more marked for more severe dyspnea. There was a 3-fold increase in episodic wheezing accompanied by shortness of breath among the more intensely exposed workers. There was no relationship between exposure and FEV1.0 or FVC.

The high prevalence of respiratory symptoms associated with exposure, in the absence of spirometric abnormalities associated with exposure, could be a result of unmeasured gas exchange abnormalities among workers with long-term exposure to paraquat.