Exposure to ambient particulate matter and hyperuricemia: An eight-year prospective cohort study on male traffic officers in China

Background and objectives: Studies on the effects of airborne particulates of diameter ≤ 1 µm (PM₁), airborne particulates of diameter ≤ 2.5 µm (PM_2.5) and airborne particulates of diameter ranges from 1 to 2.5 µm (PM_1-2.5) on incidence of hyperuricemia are limited. We aimed to investigate the associations between PM₁, PM_2.5, and PM_1-2.5 and hyperuricemia among male traffic officers.

Methods: We conducted a prospective cohort study of 1460 traffic officers without hyperuricemia in Guangzhou, China from 2009 to 2016. Exposures of PM₁ and PM_2.5 were estimated with a spatiotemporal model. PM_1-2.5 concentrations were calculated by subtracting PM₁ from PM_2.5 concentrations. Cox's proportional hazards regressions models were used to examine the association between PM₁, PM_2.5, and PM_1-2.5 and hyperuricemia, adjusted for potential confounders. Associations between PM₁, PM_2.5, and PM_1-2.5 and serum uric acid (SUA) levels were evaluated with multiple linear regression models.

Results: Hazard ratios (HRs) and 95% confidence intervals (CIs) of hyperuricemia associated with 10 μg/m³ increment in PM₁, PM_2.5, and PM_1-2.5 were 1.67 (95% CI:1.30-2.36), 1.49 (95% CI: 1.27-1.75), and 2.18 (95% CI: 1.58-3.02), respectively. The SUA concentrations increased by 12.23 μmol/L (95% CI: 5.91-18.56), 6.93 μmol/L (95% CI: 3.02-10.84), and 8.72 μmol/L (95% CI: 0.76-16.68) per 10 μg/m³ increase in PM₁, PM_2.5, and PM_1-2.5, respectively. Stratified analyses indicated the positive associations of PM_2.5 and PM_1-2.5 with SUA levels were stronger in non-smokers, and PM₁, PM_2.5, and PM_1-2.5 with SUA levels were stronger in non-drinkers.

Conclusion: Long-term PM₁, PM_2.5, and PM_1-2.5 exposures may increase the risk of hyperuricemia and elevate SUA levels among male traffic officers, especially in non-smokers and non-drinkers.