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Air pollution a leading cause of cancer - U.N. agency
http://www.reuters.com/article/2013/10/17/us-cancer-pollution-idUSBRE99G0BB20131017

(Reuters) - The air we breathe is laced with cancer-causing substances and
is being officially classified as carcinogenic to humans, the World Health
Organization's cancer agency said on Thursday.

The International Agency for Research on Cancer (IARC) cited data
indicating that in 2010, 223,000 deaths from lung cancer worldwide resulted
from air pollution, and said there was also convincing evidence it
increases the risk of bladder cancer.

Depending on the level of exposure in different parts of the world, the
risk was found to be similar to that of breathing in second-hand tobacco
smoke, Kurt Straif, head of the agency's section that ranks carcinogens,
told reporters in Geneva.

"Our task was to evaluate the air everyone breathes rather than focus on
specific air pollutants," deputy head Dana Loomis said in a statement. "The
results from the reviewed studies point in the same direction: the risk of
developing lung cancer is significantly increased in people exposed to air
pollution."

Air pollution, mostly caused by transport, power generation, industrial or
agricultural emissions and residential heating and cooking, is already
known to raise risks for a wide range of illnesses including respiratory
and heart diseases.

Research suggests that exposure levels have risen significantly in some
parts of the world, particularly countries with large populations going
through rapid industrialization, such as
China<http://www.reuters.com/places/china>
.

IARC reviewed thousands of studies on air pollution tracking populations
over decades and other research such as those in which mice exposed to
polluted air experienced increased numbers of lung tumors.

In a statement released after reviewing the literature, the Lyon-based
agency said both air pollution and "particulate matter" - a major component
of it - would now be classified among its Group 1 human carcinogens.

That ranks them alongside more than 100 other known cancer-causing
substances in IARC's Group 1, including asbestos, plutonium, silica dust,
ultraviolet radiation and tobacco smoke.

CARCINOGEN ENCYCLOPAEDIA

Air pollution is highly variable over space and time.

Loomis said there was relatively high exposure in Asia, South Asia, eastern
North America, some places in Central America and Mexico, as well as North
Africa.

But although both the composition and levels of air pollution can vary
dramatically from one location to the next, IARC said its conclusions
applied to all regions of the world.

"Our conclusion is that this is a leading environmental cause of cancer
deaths," Dr. Christopher Wild, director of IARC, told the news briefing in
Geneva.

IARC's ranking monographs program, sometimes known as the "encyclopedia of
carcinogens", aims to be an authoritative source of scientific evidence on
cancer-causing substances.

It has already classified many chemicals and mixtures that can be
components of air pollution, including diesel engine exhaust, solvents,
metals and dusts. But this is the first time that experts have classified
air pollution as a cause of cancer.

Wild said he hoped the comprehensive evidence would help the WHO, which is
revising its global 2005 guidelines on air quality. The U.N. agency makes
on recommendations on public health issues to its 193 member states.

Asked why it had taken so long to reach the conclusion, he said that one
problem was the time lag between exposure to polluted air and the onset of
cancer.

"Often we're looking at two, three or four decades once an exposure is
introduced before there is sufficient impact on the burden of cancer in the
population to be able to study this type of question," he said.

(Editing by Alison Williams)