[Pharmwaste] Lingering toxins continue to cause cancer: study
dldebiasi at deq.virginia.gov
Thu Dec 13 13:06:16 EST 2007
Lingering toxins continue to cause cancer: study
Thursday, December 13, 2007
Banned pesticides and other toxic chemicals lingering in the environment
put people at an increased risk of developing non-Hodgkin lymphoma,
according to a B.C. Cancer Agency study.
The study - the largest of its kind ever done on the link between the
illness and contaminants such as polychlorinated biphenyls and
agricultural products such as herbicides, insecticides and fungicides -
will be published in the International Journal of Cancer this week.
Researchers found people with the highest levels of a certain type of
insecticide in their blood had 2.7 times the risk of developing
non-Hodgkin lymphoma as those with the lowest amounts.
That strong link involved a metabolite of the insecticide chlordane.
People with PCBs in their blood, meanwhile, had twice the risk of
developing the disease as those with the lowest exposures. That's about
the same level of increased risk as having a family history of
Non-Hodgkin lymphoma is the fifth most common cancer in Canada and the
most common type of lymphoma. In 2007, nearly 1,000 B.C. residents will
be diagnosed with the disease and nearly 400 will die from it.
John Spinelli, a senior scientist at the cancer agency and lead author
of the study, said the findings prove more research on synthetic
compounds should be done to determine whether they are unsafe for
The compounds in the study were banned because they were shown to cause
cancer in animal studies.
"Now we have sufficient evidence in humans," Spinelli said.
He noted that when researchers first proposed the study several years
ago, they wanted to explore why non-Hodgkin lymphoma had been steadily
increasing around the world for 30 years.
After the study began, the rates began levelling off, raising
scientists' curiosity because "it clearly wasn't genetics that would
change that since genetics don't change that fast."
It is thought the disease rates have flattened out in the past three or
four years because of improvements to the environment - the result of
banning the chemicals years earlier.
Even though the synthetically produced chemical compounds in the study
have been banned in Canada for decades, they still exist in some types
of flame retardants and equipment (PCB insulating fluid in older
They also pose a threat because some - such as DDT to kill mosquitoes
and prevent malaria - are still used in other countries. The compounds
are found throughout the world, circulating in the atmosphere, oceans,
soil and animal feed.
"These kinds of contaminants and pollutants have a very long half life
which means they may take decades or more to degrade. They were banned
20 to 30 years ago but maybe we should have acted earlier," said
"We can't really avoid these contaminants," he said in an interview. "In
fact they are still going to be in organic foods because although
farmers aren't spraying these chemicals on crops any more, [residue] is
still in the air and in the soil. There's not much we can do to keep
from being exposed to them," he said, adding that environmental toxins
are believed to be the cause of about 10 per cent of cancers.
Many of the chemicals that have replaced the banned substances are
largely water soluble and degrade much more quickly so they don't pose
as much of a problem to the environment and human health, while "PCBs
accumulate and get stored in the fatty tissue of fish and animals or
animal products like butter which we eat so they never really vanish,"
"But we do expect that the risk of this type of cancer from these kinds
of contaminants will go down over time," he added.
The study involved taking blood samples from 422 newly diagnosed
non-Hodgkin lymphoma patients (before their treatment began) and 460
healthy control subjects between March 2000 and February 2004. Samples
were sent to a toxicology laboratory in Quebec for analysis of compounds
called organochlorines, pesticides and pesticide byproducts.
"Our results support the hypothesis that certain PCB [types] and ...
pesticides increase the risk of [non-Hodgkin lymphoma]," the study
Other known risk factors for developing non-Hodgkin lymphoma are immune
suppression treatment after organ transplants, HIV/AIDS, previous
chemotherapy treatment and certain viruses such as Epstein-Barr or
Spinelli said research he and his colleagues are doing looks at whether
similar chemical compounds and environmental contaminants are also a
risk factor for cancers such as breast and ovarian.
The $800,000 study by Spinelli and his nine co-researchers was funded
by the Canadian Cancer Society (through the National Cancer Institute of
Canada) and the Canadian Institutes of Health Research. Called
Organochlorines and Risk of non-Hodgkin Lymphoma, it will be published
Sun Health Issues Reporter
pfayerman at png.canwest.com
(c) Vancouver Sun
Deborah L. DeBiasi
Email: dldebiasi at deq.virginia.gov
WEB site address: www.deq.virginia.gov
Virginia Department of Environmental Quality
Office of Water Permit Programs
Industrial Pretreatment/Toxics Management Program
PPCPs, EDCs, and Microconstituents
Mail: P.O. Box 1105, Richmond, VA 23218 (NEW!)
Location: 629 E. Main Street, Richmond, VA 23219
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