Working with poultry linked to certain cancers
By Adam Marcus,
Reuters November 2, 2009 4:08 PM
Chickens forage at a chicken farm on December 18, 2008 in Nantong of Jiangsu
Photograph by: China Photos, Getty Images
NEW YORK -- Poultry workers may be at particularly high risk of developing
several forms of cancer, according to a new study that points to viruses
carried by birds as a possible cause.
The findings come from an ongoing effort by researchers to identify
job-related illnesses in the nation's 250,000 poultry processing workers. It
found higher than expected rates of cancers of the sinuses, mouth and blood,
as well as other forms of the disease, in poultry plant employees.
The researchers said cancer-causing viruses transmitted during the handling
and slaughter of chickens and turkeys, as well as environmental factors such
as exposure to fumes generated during the wrapping, smoking and cooking of
meat, along with other aspects of production, may be to blame for the
increased rates of illness.
Some of the viruses present in birds are found in the egg supply. And
because many vaccines are made using chicken eggs as incubators, the viruses
have also been found in the vaccine stock - in particular, the shots against
measles, mumps, and yellow fever, according to the researchers. However,
scientists have not found evidence that the presence of the viruses is
harmful to humans.
Still, "These observations have serious public health implications and
reiterate the urgent need for studies to be conducted in subjects that have
high exposure to the (cancer-causing) viruses of poultry, such as workers in
poultry slaughtering and processing plants," they wrote in the journal
Cancer Causes & Control.
Study leader Eric Johnson, an epidemiologist at the University of North
Texas Health Science Center, in Fort Worth, said the viruses pose no risk to
consumers who eat properly cooked poultry products, including eggs. But
eating raw or undercooked eggs and poultry or handling raw meat may be
hazardous, he told Reuters Health.
The study compared cancer deaths in 2,580 members of the Baltimore meat
cutter's union who worked exclusively in six Maryland poultry plants between
1954 and 1979. By 2003, 790 of those workers had died, and the researchers
were able to determine the cause of death for 756.
Of the 756 total deaths, 187 were from cancer. Although the overall death
rate from cancer was not unusually high, the death rate was much
greater-ranging from 3.5 to nearly 9 times higher-for several forms of the
disease, including cancer of the tonsils, nasal cavity and sinuses, and a
blood cancer called myelofibrosis.
Death rates from certain cancers-including of the tongue, liver and
esophagus-also were higher than normal among various groups of workers even
when the overall rates were what would be expected in unremarkable, the
For certain cancers, the risks were greater depending on the workers' sex or
race. Those differences may reflect divisions of labor in poultry plants,
where women and men, and whites and blacks, historically were assigned
different duties, the researchers noted.
Richard Lobb, a spokesman for the National Chicken Council, an industry
group, dismissed the study as an "astounding piece" of flawed research. Lobb
said the scientists did not adequately account for the known cancer risks of
tobacco and alcohol use in the workers.
In addition, the "suggestion that raw chickens carry viruses that cause
cancer in humans is pure supposition unsupported by any scientific facts or
studies," he told Reuters Health.
Johnson acknowledged that the study's inability to account for the effects
of tobacco and alcohol use was a limitation. But he said other research has
shown that poultry and meat industry workers have higher-than-normal odds of
developing cancer, even after controlling for smoking.
What's more, smoking and alcohol are not linked to the blood cancers that
seem to be more common among poultry workers in the new research, he said.
Moreover, Johnson said, the link between avian viruses and cancer in animals
is well established.
"We've known that for years. It's just that we've never had the human
evidence," he said. "That's what we are providing for the first time."
SOURCE: Cancer Causes & Control, Published Online October 22, 2009.
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