Effects of exposure to glyphosate on oxidative stress, inflammation, and lung function in maize farmers, Northern Thailand

BACKGROUND: Glyphosate is a herbicide which is commonly used in agricultural areas. However, previous studies on glyphosate exposure in farmers and their health are still scarce. METHODS: A longitudinal pre-post study was performed among maize farmers. Information from questionnaires, urine and blood samples, and lung function were collected a day before and a day after glyphosate application in the morning. The urine samples were analyzed using liquid chromatography-tandem mass spectrometry to detect glyphosate levels. Serum samples were analyzed to detect malondialdehyde (MDA), glutathione (GHS), and C-reactive protein (CRP) levels using thiobarbituric acid, dithiobisnitrobenzoic acid, and nephelometry, respectively. Lung function performances were measured using a spirometer. RESULTS: A total of 180 maize farmers met the study inclusion criteria. After glyphosate application, it was found that increased urinary glyphosate levels contributed to increased serum MDA (β = 0.024, 95% CI = 0.000, 0.0047) and decreased serum GHS (β = -0.022, 95% CI = -0.037, -0.007), FEV(1) (β = -0.134, 95% CI = -0.168, -0.100), FEV(1)/FVC (β = -0.062, 95% CI = -0.082, -0.042) and PEF (β = -0.952, 95% CI = -1.169, -0.735). CONCLUSIONS: Exposure to glyphosate during glyphosate application had significant effects on oxidative stress and lung function in maize farmers.