Official label of 'carcinogen' means exhaust emissions should be treated in same league as passive smoking or UV radiation
Associated Press
A diesel commuter train at Preston station: the WHO study said as so many people breathe in diesel fumes action needs to be taken. Photograph: Keith Morris/Alamy
Diesel exhaust causes cancer, the World Health Organisation has declared, a ruling it said could make exhaust as important a public health threat as passive smoke.
The
risk of getting cancer from diesel fumes is small, but since so many
people breathe in the fumes in some way, the WHO's science panel said
raising the status of diesel exhaust to carcinogen from "probable
carcinogen" was an important shift.
"It's on the same order of
magnitude as passive smoking," said Kurt Straif, director of the IARC
department that evaluates cancer risks, on Tuesday. "This could be
another big push for countries to clean up exhaust from diesel engines."
Since
so many people are exposed to exhaust, Straif said there could be many
cases of lung cancer connected to the contaminant. He said the fumes
affected groups including pedestrians on the street, ship passengers and
crew, railroad workers, truck drivers, mechanics, miners and people
operating heavy machinery.
The new classification followed a
week-long discussion in Lyon, France, by an expert panel organised by
the International Agency for Research on Cancer. The panel's decision
stands as the ruling for the IARC, the cancer arm of the WHO.
The
last time the agency considered the status of diesel exhaust was in
1989, when it was labeled a probable carcinogen. Reclassifying diesel
exhaust as carcinogenic puts it into the same category as other known
hazards such as asbestos, alcohol and ultraviolet radiation.
The
US government, however, still classifies diesel exhaust as a "likely
carcinogen". Experts said new diesel engines spew out fewer fumes but
further studies are needed to assess any potential dangers. "We don't
have enough evidence to say these new engines are zero risk, but they
are certainly lower risk than before," said Vincent Cogliano of the US
Environmental Protection Agency.
Experts in Lyon had analysed
published studies, evidence from animals and limited research in humans.
One of the biggest studies was published in March by the US National
Cancer Institute. That paper analysed 12,300 miners for several decades
starting in 1947. Researchers found miners heavily exposed to diesel
exhaust had a higher risk of dying from lung cancer.
Lobbyists for
the diesel industry argued the study wasn't credible because
researchers didn't have exact data on how much exposure miners got in
the early years of the study; they simply asked them to remember what
their exposure was like. A person's risk for cancer depends on many
variables, from genetic makeup to the amount and length of time of
exposure to dangerous substances.
A US group that represents
diesel engine makers said major technological advances in the last
decade have cut emissions from trucks and buses by more than 95% for
nitrogen oxides, particulate and sulfur emissions. Some experts said the
new classification wasn't surprising.
"It's pretty well known
that if you get enough exposure to diesel, it's a carcinogen," said Ken
Donaldson, a professor of respiratory toxicology at the University of
Edinburgh, who was not part of the IARC panel. He said the thousands of
particles, including some harmful chemicals, in the exhaust could cause
inflammation in the lungs and over time, that could lead to cancer.
But
Donaldson said lung cancer was caused by multiple factors and that
other things like smoking were far more deadly. He said the people most
at risk were those whose jobs exposed them to high levels of diesel
exhaust, like truck drivers, mechanics, or miners.
"For the man on
the street, nothing has changed," he said. "It's a known risk but a low
one for the average person, so people should go about their business as
normal ... you could wear a mask if you want to, but who wants to walk
around all the time with a mask on?"
