Long-term respiratory health effects of the herbicide, paraquat, among workers in the Western Cape.

Abstract

Objective-To evaluate the possible effects of paraquat spraying among workers on deciduous fruit farms in the Western Cape, South Africa. Paraquat is a commonly used herbicide world wide and is a well documented cause of pulmonary fibrosis in studies of laboratory animals and in humans after exposure to a high dose (usually accidental or as parasuicide). The respiratory eVects of long term, low dose exposure to paraquat have not been fully evaluated. Methods-A cross sectional study of 126 workers. Administered questionnaires generated information on exposure, respiratory symptoms, and potential confounding variables. Spirometry and gas transfer were measured and chest radiographs performed. Oxygen desaturation on exercise testing was by oximetry during a modified stage one exercise test. Results-No association was found between long term exposure to paraquat and reported symptoms, spirometry ( forced vital capacity (FVC), forced expiratory volume in 1 second (FEV 1 ), FEV 1 /FVC) and gas transfer (T LCO and KCO) or chest radiography.Multivariate analysis showed a significant relation between measures of long term exposure to paraquat and arterial oxygen desaturation during exercise independent of short term exposure. Conclusion-Previous studies have not shown a significant relation between measures of exposure to paraquat and standard tests of lung function. Arterial oxygen desaturation during exercise represents a more sensitive test. The findings indicate that working with paraquat under usual field conditions is associated with abnormal exercise physiology in a dose dependent fashion independent of recent exposure and acute poisoning events. (Occup Environ Med 1999;56:391-396)

Pulmonary Function and Exercise-associated Changes with Chronic Low-Level Paraquat Exposure

“…Dalvie and coworkers did not observe an association of paraquat exposure and respiratory symptoms, spirometry, or carbon monoxide diffusing capacity, but they did report a positive association of chronic paraquat exposure and arterial oxygen desaturation during maximum exercise (20). However, 28% of the saturation traces were considered unreadable, and among those with readable traces the magnitude of the effect was small.…”

“…However, the occupational hazards presented by chronic paraquat exposure are less well characterized, and epidemiologic studies have not shown consistent pulmonary changes among paraquat handlers (16)(17)(18)(19)(20). Castro-Gutierrez and colleagues (19) found that exposure to paraquat, as estimated by skin rash symptoms, was related to selfreported respiratory symptoms (chronic bronchitis and episodic dyspnea with wheezing) but they did not observe an association of paraquat exposure with pulmonary function changes measured by spirometry.…”

“…A more recent study by Dalvie and coworkers of 126 paraquat applicators in the Western Cape region of South Africa classified exposure using a job-exposure matrix (20). Dalvie and coworkers did not observe an association of paraquat exposure and respiratory symptoms, spirometry, or carbon monoxide diffusing capacity, but they did report a positive association of chronic paraquat exposure and arterial oxygen desaturation during maximum exercise (20).…”

“…However, 28% of the saturation traces were considered unreadable, and among those with readable traces the magnitude of the effect was small. Additional limitations from other epidemiologic studies include small sample sizes (16,21), poor exposure characterization (18,19), potential for selection bias, insensitive outcome measures (19), and lack of biological measures of exposure (20).…”

Identifying Epigenetic Endpoints of Pesticide Exposure Can Curtail Risk to Develop Cancer: A Review.

“…Paraquat, a herbicide, is associated with respiratory disorder on high exposure (Dalvie et al, 1999). It shows mild direct mutagenicity and is categorized as a Group E pesticide (showing no evidence of carcinogenicity).…”