London: Long-term exposure to air pollution may not only lead to lung cancer but also increase the risk of mortality from kidney, bladder and colorectal cancer, a large-scale study warns.
Air pollution is classified as carcinogenic to humans given its association with lung cancer, but there is little evidence for its association with cancer at other body sites, researchers said.
In a large-scale study led by the Barcelona Institute for Global Health (ISGlobal) in Spain, researchers observed an association between some air pollutants and mortality from kidney, bladder and colorectal cancer.
The study, published in the journal Environmental Health Perspectives, included more than 6,00,000 adults in the US who were followed for 22 years (from 1982 to 2004).
The scientific team examined associations of mortality from cancer at 29 sites with long-term residential exposure to three ambient pollutants: PM2.5, nitrogen dioxide (NO2) and ozone (O3).
Over 43,000 non-lung cancer deaths were registered among the participants. PM2.5 was associated with mortality from kidney and bladder cancer, with a 14 and 13% increase, respectively, for every 4.4 micro-grammes per cubic metre ( µg/m3) increase in exposure.
In turn, exposure to NO2 was associated with colorectal cancer death, with a 6% increase per 6.5 parts per billion (ppb) increment. No significant associations were observed with cancer at other sites, researchers said. "Although a number of studies associate lung cancer with air pollution, there is still little evidence for associations at other cancer sites," said Michelle Turner, ISGlobal researcher and first author of the study. "This research suggests that air pollution was not associated with death from most non-lung cancers, but the associations with kidney, bladder and colorectal cancer deserve further investigation," she said.