Cancer Burden Disease Attributable to PM2.5 and Health Risk by PM2.5-bound Toxic Species in Two Urban Chilean Municipalities

This study aimed to estimate the environmental cancer disease burden in adults attributable to fine particulate matter (PM2.5) exposure using Ostro's function methodology, and health risk indexes for particle-bound toxic chemicals through hazard quotients (HQ, HI) and carcinogenic risk (CR, CRI) indexes from EPA guidelines, of two urban Chilean Municipalities: Coyhaique and Independencia. Quantification of chemical species (OC, EC, metals, and PAHs) was done at the Lamont-Doherty Earth Observatory of Columbia University, USA. Modern carbon in OC and EC analysis showed that the principal source of PM2.5 emission in Coyhaique was firewood burning compared with Independencia. The total PAHs and B[a]P concentrations were 6.3 and 8.9 times higher in Coyhaique than in Independencia. In contrast, As and Pb levels were significantly greater in Independencia. The HI was 14.5 and 2.37 times the limit considered acceptable (HI > 1) in Coyhaique and Independencia, explained 92.45% by B[a]P and 66.99% by As, respectively. CRI exceeded the threshold (1 x 10-6) in Coyhaique and Independencia, explained by As (75.38%) plus B[a]P (20.30%) and As (97.01%). The attributable fraction (AF) of deaths due to lung cancer from long-term exposure to PM2.5 reached 54% (95% CI: 25-72) in Coyhaique vs. 43% (95% CI: 19-46) in Independencia. The AFfor cardiopulmonary cancer were 40% (95% CI: 17-57) and 32% (95% CI: 12-46), respectively. A relevant fraction of the cancer cases and potential expected adverse effects would be attributable to long-term exposure to PM2.5and the presence of chemical compounds bound to the particles. These results deserve further study to help guide policy in different environments, mainly carcinogenic PM2.5-bound toxic species from other emission sources, particularly firewood burning.

Automated summary

This study estimated the cancer disease burden in two urban Chilean Municipalities, Coyhaique and Independencia, attributable to exposure to fine particulate matter (PM2.5). The results showed that the primary source of PM2.5 in Coyhaique was firewood burning, resulting in higher concentrations of PAHs and B[a]P compared to Independencia. However, Independencia had significantly higher levels of As and Pb. The health risk indexes (HI and HQ) exceeded acceptable limits in both cities, mainly due to B[a]P and As. The attributable fraction of deaths due to lung cancer and cardiopulmonary cancer from long-term PM2.5 exposure was higher in Coyhaique compared to Independencia. The presence of chemical compounds bound to particles from PM2.5 exposure contributed to a significant fraction of cancer cases and potential adverse effects. Further studies are needed to inform policy-making, particularly regarding PM2.5-bound toxic species from other emission sources, such as firewood burning.