Occupational exposure to heavy metals and its association with DNA oxidative stress among urban green space workers.

Heavy metals impact the urban population, the environment, and workers exposed to these pollutants. Green space workers during the day shift and peak city traffic hours have constant exposure to air pollutants. This study aimed to determine the concentration of heavy metals including, Cd, Co, and Zn in urine and breathing air samples among green space workers as the exposed group and office employees as the control group of Tehran Municipality and investigate the associations between heavy metal exposure and DNA oxidative stress. In addition, a comparative analysis was conducted between those groups. NIOSH-7300 and NIOSH-8310 were used to collect and prepare air and urine samples. The final sample concentration was measured by ICP-OES. ZellBio GmbH kits were used to measure the levels of urinary 8-OHDG (8-hydroxy-2'-deoxyguanosine), a biomarker of DNA oxidative stress. The mean concentration of urinary and air heavy metals and urinary 8-OHDG, except for Cd in the air, exhibited a statistically significant increase in the exposed group compared to the control group (P < 0.001). Moreover, the Pearson correlation coefficient (R) between urinary heavy metals and 8-OHDG values in the exposed group revealed that there are significant relations between urinary Cd, Co, and Zn with 8-OHDG: R = 0.734, R = 0.836, and R = 0.584 respectively (P < 0.001). No correlations were observed between heavy metals and 8-OHDG in the control group. Findings revealed that cobalt and cadmium exhibit the most significant influence on changes in oxidative stress, as indicated by the dependent variable 8-OHDG. This study compared urban green space workers with office employees, revealing elevated concentrations of Cd, Co, and Zn in the air and urine of the exposed group. Green space workers exhibited significantly higher urinary 8-OHDG, indicating increased DNA oxidative stress. The findings highlight the urgent need for protective measures and occupational health interventions for green space workers.