Air pollution exposure and urinary tract cancer risk

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Air pollution exposure and urinary tract cancer risk

Air pollution is a form of pollution, that is the set of all physical, chemical and biological agents that modify the natural characteristics of the earth's atmosphere. The human health effects of poor air quality are far-reaching, but primarily affect the body's respiratory system and cardiovascular system.

Individual reactions to air pollution depend on the type of pollutant a person is exposed to, the degree of exposure, the individual's health and genetics. Indoor air pollution and poor urban air quality are listed as two of the worst toxic pollution problems in the world in the 2008 report.

Outdoor air pollution alone causes 2.1 to 4.21 millions of deaths every year. Overall, air pollution causes the deaths of approximately 7 million people worldwide each year and is the single largest environmental health risk in the world.

Productivity losses and degraded quality of life caused by air pollution are estimated to cost the world economy per year. Various pollution control technologies and strategies are available to reduce air pollution.

Air pollution exposure and urinary tract cancer risk

The article Air pollution exposure and bladder, kidney and urinary tract cancer risk: A systematic review, published on the Environmental pollution, links this type of cancer with air pollution.

In the abstract we can read: "Background: Exposure to outdoor air pollution has been linked to lung cancer, and suspicion arose regarding bladder, kidney, and urinary tract cancer (urological cancers). However, most of evidence comes from occupational studies; therefore, little is known about the effect of exposure to air pollution on the risk of urological cancers in the general population.

Method: We systematically searched Medline, Scopus, and Web of Science for articles investigating the associations between long-term exposure to air pollution and the risk of urological cancer (incidence or mortality). We included articles using a specific air pollutant (PM10, PM2.5, …) or proxies (traffic, proximity index …).

We assessed each study's quality with the Newcastle-Ottawa scale and rated the quality of the body of evidence for each pollutant-outcome with the GRADE approach. The different study methodologies regarding exposure or outcome prevented us to perform a meta-analysis.

Results: twenty articles (four case-control, nine cohort, and seven ecologic) met our inclusion criteria and were included in this review: eighteen reported bladder, six kidney, and two urinary tract. Modeling air pollutants was the most common exposure assessment method.

Most of the included studies reported positive associations between air pollution and urological cancer risk. However, only a few reached statistical significance (e.g. for bladder cancer mortality, adjusted odds-ratio of 1.13 (1.03-1.23) for an increase of 4.4 μg.m-3 of PM2.5).

Most studies inadequately addressed confounding, and cohort studies had an insufficient follow-up. Discussion: Overall, studies suggested positive (even though mostly non-significant) associations between air pollution exposure and bladder cancer mortality and kidney cancer incidence. We need more studies with better confounding control and longer follow-ups."