Association of 2,4-dichlorophenoxyacetic acid exposure with all-cause and cancer mortality risk: a comprehensive study of 9198 participants

With 2,4-dichlorophenoxyacetic acid (2,4-D) being a widely used herbicide, understanding its potential health implications is crucial. This study investigates the association between 2,4-D exposure and all-cause and cancer mortality. A total of 9168 participants were enrolled from National Health and Nutrition Examination Survey. The levels of 2,4-D were measured with liquid chromatography/mass spectrometry. Cox proportional hazards regression analysis was conducted to explore associations with all-cause and cancer mortality. The average level of 2,4-D was 0.81 μg/l. After a median of 7.1-year follow-up, 903 all-cause and 203 cancer death occurred. Participants with higher 2,4-D levels were older, predominantly male, and exhibited a higher percentage of smokers with reduced estimated glomerular filtration rate levels. Comparing with the lowest quartile, the third quartile of 2,4-D was independently associated with decreased all-cause mortality [hazard ratio 0.79, 95% confidence interval (CI): 0.66-0.96; P = 0.015]. For cancer mortality, the highest quartile of 2,4-D was linked to increased risks (hazard ratio 2.18, 95% CI: 1.50-3.17; P < 0.001). The 2,4-D exposure was negatively associated with all-cause mortality. However, higher 2,4-D levels were consistently associated with elevated cancer mortality. These findings underscore the complex relationship between 2,4-D exposure and health outcomes, emphasizing the need for further research and consideration of multiple factors influencing mortality risks.