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 “We assumed a number of sites would be affected, but outside of the
expected lung and upper GI cancers, we were unsure which cancers
would show an association, so this really helps highlight the
breadth of involvement of particulates in the development of
cancer,” said co-lead author G. Neil Thomas, from the Institute of
Applied Health of the College of Medical and Dental Sciences at The
University of Birmingham in the UK.
Ultrafine particles can pass into the blood stream and have the
potential to impact any part of the body, Thomas told Reuters Health
by email.
The researchers began following more than 66,000 people age 65 and
older in Hong Kong between 1998 and 2001 and tracked them through
2011. They used satellite data and site monitors to estimate fine
particulate matter in the air at the subjects’ homes.
They focused on fine particulate matter, or PM2.5, which is produced
by motor vehicles, power plants and other industrial combustion,
according to the U.S. Environmental Protection Agency.
After accounting for smoking status, the researchers found that as a
subject’s home exposure to fine particles in the air increased, so
did the risk of dying from any cancer, including cancer of the upper
digestive tract, liver, bile ducts, gall bladder and pancreas.
As fine particulate concentrations increased by 10 micrograms per
cubic meter, a woman’s risk of dying from breast cancer increased by
80 percent, while a man’s risk of dying from lung cancer increased
by 36 percent, according to a report released by the journal Cancer
Epidemiology, Biomarkers & Prevention.
“Biologically there is no reason to suggestion such observations
wouldn’t apply to younger people,” Thomas said. “It is important
though to remember that cancers are chronic diseases and thus it
takes years between the exposure to the particulates to the
development of a diagnosable cancer.”
Data from other populations and countries has been similar, he said.
According to the Clean Air Act in the U.S., the average annual
concentration of fine particulate matter in the air should be 15
micrograms per cubic meter or lower. In Hong Kong, average annual
particulate matter should not exceed 35 micrograms per cubic meter
according to the Air Pollution Control Ordinance.
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“In Hong Kong the PM2.5 concentrations are not comparable to those
in North America or Europe,” said Giulia Cesaroni of the
epidemiology department of the Regional Health Service of the Lazio
Region in Rome, Italy, who was not part of the new study. “The
(World Health Organization) suggested a limit value of 10 micrograms
per cubic meter for PM2.5, and study participants are exposed to a
mean value of 34 micrograms per cubic meter.”
“However, associations between air pollution and cancer risk have
been found in other settings at low concentrations,” Cesaroni said.
The EPA provides air quality index forecasts for the U.S. at
airnow.gov.
Particulate matter can cause cancer because it often contains toxic
chemicals and causes inflammation, among other mechanisms, Cesaroni
told Reuters Health by email.
“At an individual level the strongest risk factors for cancer are
smoking and diet,” she said. “However, at a population level, given
the wide distribution of exposure, even a small increase in risk can
result in a large number of cases.”
Pollution also increases the risk of cardiorespiratory disease,
Thomas said.
“The risk is not as great as that from smoking tobacco (and quitting
greatly improves health of those smoking and those exposed to the
second hand smoke) but is clearly present,” he said.
SOURCE: http://bit.ly/1SX4se1 Cancer Epidemiology, Biomarkers and
Prevention, released April 29, 2016.
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