Exposure to PM Metal Constituents and Liver Cancer Risk in REVEAL-HBV.

BACKGROUND

Ambient particulate matter is classified as a human Class 1 carcinogen, and recent studies found a positive relationship between fine particulate matter (PM) and liver cancer. Nevertheless, little is known about which specific metal constituent contributes to the development of liver cancer.

OBJECTIVE

To evaluate the association of long-term exposure to metal constituents in PM with the risk of liver cancer using a Taiwanese cohort study.

METHODS

A total of 13,511 Taiwanese participants were recruited from the REVEAL-HBV in 1991-1992. Participants' long-term exposure to eight metal constituents (Ba, Cu, Mn, Sb, Zn, Pb, Ni, and Cd) in PM was based on ambient measurement in 2002-2006 followed by a land-use regression model for spatial interpolation. We ascertained newly developed liver cancer (ie, hepatocellular carcinoma [HCC]) through data linkage with the Taiwan Cancer Registry and national health death certification in 1991-2014. A Cox proportional hazards model was utilized to assess the association between exposure to PM metal component and HCC.

RESULTS

We identified 322 newly developed HCC with a median follow-up of 23.1 years. Long-term exposure to PM Cu was positively associated with a risk of liver cancer. The adjusted hazard ratio (HR) was 1.13 (95% confidence interval [CI], 1.02-1.25; P = 0.023) with one unit increment on Cu normalized by PM mass concentration in the logarithmic scale. The PM Cu-HCC association remained statistically significant with adjustment for co-exposures to other metal constituents in PM.

CONCLUSION

Our findings suggest PM containing Cu may attribute to the association of PM exposure with liver cancer.