[Pharmwaste] Common chemicals are linked to breast cancer

[DeBiasi,Deborah]

http://www.latimes.com/news/printedition/front/la-na-cancer14may14,1,515
4634.story?ctrack=3&cset=true

Common chemicals are linked to breast cancer

Of the 216 compounds, many in the air, food or everyday items.
By Marla Cone, Times Staff Writer
May 14, 2007 


More than 200 chemicals - many found in urban air and everyday consumer
products - cause breast cancer in animal tests, according to a
compilation of scientific reports published today.

Writing in a publication of the American Cancer Society, researchers
concluded that reducing exposure to the compounds could prevent many
women from developing the disease. 

The research team from five institutions analyzed a growing body of
evidence linking environmental contaminants to breast cancer, the
leading killer of U.S. women in their late 30s to early 50s. 

Experts say that family history and genes are responsible for a small
percentage of breast cancer cases but that environmental or lifestyle
factors such as diet are probably involved in the vast majority.

"Overall, exposure to mammary gland carcinogens is widespread," the
researchers wrote in a special supplement to the journal Cancer. "These
compounds are widely detected in human tissues and in environments, such
as homes, where women spend time."

The scientists said data were too incomplete to estimate how many breast
cancer cases might be linked to chemical exposures.

But because the disease is so common and the chemicals so widespread,
"the public health impacts of reducing exposures would be profound even
if the true relative risks are modest," they wrote. "If even a small
percentage is due to preventable environmental factors, modifying these
factors would spare thousands of women."

The three reports and a commentary were compiled by researchers from the
Silent Spring Institute, a women's environmental health organization in
Newton, Mass.; Harvard's Medical School and School of Public Health in
Boston; the Roswell Park Cancer Institute in Buffalo, N.Y.; and USC's
Keck School of Medicine. Silent Spring Institute Executive Director
Julia Brody led the team.

In response to the findings, Susan G. Komen for the Cure, a breast
cancer prevention group that funded the work, pledged an additional $5
million for developing research tools to root out environmental causes.

Reviewing hundreds of existing studies and databases, the team produced
what it called "the most comprehensive compilation to date of chemicals
identified as mammary carcinogens." No new chemical testing was
conducted for the reports.

The researchers named 216 chemicals that induce breast tumors in
animals. Of those, people are highly exposed to 97, including industrial
solvents, pesticides, dyes, gasoline and diesel exhaust compounds,
cosmetics ingredients, hormones, pharmaceuticals, radiation, and a
chemical in chlorinated drinking water.

"Almost all of the chemicals were mutagenic, and most caused tumors in
multiple organs and species; these characteristics are generally thought
to indicate likely carcinogenicity in humans, even at lower exposure
levels," they reported.

For many of the compounds, the federal government has not used animal
breast cancer data when conducting human risk assessments, which are the
first step toward regulating chemicals or in setting occupational
standards to protect workers. Companies are not required to screen women
who work with the chemicals for breast cancer. 

"Regulators have not paid much attention to potential mammary
carcinogens," the researchers wrote.

Toxicologists say that other mammals, such as rats and mice, often
develop the same tumors as humans do, and that animal tests are
efficient means of testing the effects of chemicals. Environmental
regulators, however, often want conclusive human data before taking
action. 

Animal studies generally use high doses of a substance to simulate a
lifetime of exposure, and then the results are extrapolated to the lower
levels that people are exposed to.

Ana Soto, a Tufts University professor of cell biology who specializes
in cellular origins of cancer and effects of hormone-disrupting
contaminants, said there probably was a link between breast cancer and
exposures to chemicals in the environment, particularly early in life.

"I cannot say I'm convinced, but what I can say is that it's a very
likely, very plausible hypothesis," said Soto, who did not participate
in the new research. "More and more, cancer looks like an environmental
disease." 

Twenty-nine of the chemicals are produced in volumes exceeding 1 million
pounds annually in the United States. 

Seventy-three are present in consumer products or are food contaminants
- 1,4-dioxane in shampoos, for example, or acrylamide in French fries.
Thirty-five are common air pollutants, 25 are in workplaces where at
least 5,000 women are employed, and 10 are food additives, according to
the reports.

There are probably many more than 216, the research team said, because
only about 1,000 of the 80,000 chemicals registered for use in the
United States have been tested on animals to see whether they induce
cancerous tumors or mutate DNA. Such tests cost $2 million each.

Because epidemiological studies are difficult to conduct and full of
uncertainties, human data are "still relatively sparse," the researchers
wrote. Only 152 studies worldwide have examined whether women exposed to
contaminants are more likely to have breast cancer - compared with
nearly 1,500 that have explored the links between diet and the disease -
and most of the 216 carcinogens were not included. 

"Despite this large remaining gap, research in the last five years has
strengthened the human evidence that environmental pollutants play a
role in breast cancer risk," the researchers wrote. They said the
existing studies suggested "substantial public health impact."

Human evidence is particularly strong for PCBs, or polychlorinated
biphenyls - compounds widely used in the 1940s to late 1970s that still
contaminate fish and other foods - and for polycyclic aromatic
hydrocarbons, or PAHs, found in diesel and gasoline exhaust. 

Solvents in dry cleaning, aircraft maintenance and other jobs also may
increase breast cancer risk. 

Some of the chemicals named as breast carcinogens already are regulated
to protect public health, but some, particularly those in consumer
products, are not. 

The scientists conducted the review hoping to lay the groundwork for new
human studies, as well as to persuade regulators to use existing animal
data to strengthen regulations and require more testing of chemicals. 

"Animal models are the primary means of understanding and anticipating
effects of chemicals in humans," they wrote. "All known human
carcinogens ... are also carcinogenic in animals."

Emerging evidence suggests that the roots of breast cancer are in
infancy or the womb. More animal and human research should focus on such
early exposure, said Patricia Hunt, a Washington State University School
of Molecular Biosciences professor.

But Hunt and Soto urged society not to wait for scientific proof to
reduce exposure to the chemicals.

"When you look at their list of chemicals, we are exposed to all of it,"
Soto said. "We know humans are exposed to mixtures, and studying
mixtures is very difficult. We will never have the whole picture, and it
will take many, many years to collect epidemiological evidence, so we
should take some preventive measures now."

Although virtually all women are exposed to the chemicals, some may be
more susceptible because of differing metabolism or ability to repair
DNA.

Breast cancer is probably triggered by an interaction of multiple
environmental and genetic factors. 

Experts have long suspected diet plays a role. But the new research
found "no association that is consistent, strong and statistically
significant" for any particular foods raising or reducing breast cancer
risk. There is substantial evidence, however, that regularly consuming
alcohol, being obese and being sedentary increase risk.

About 178,000 new cases will be diagnosed this year in the United
States. 

The reports are at http://www.silentspring.org/sciencereview . 


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marla.cone at latimes.com

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(INFOBOX BELOW)

Chemical carcinogens

Researchers name 216 chemicals that cause breast cancer in animal tests.
Here are some of the most widespread:

Chemical Source/use
 
1,4-dioxane 	Detergents, shampoos, soaps  
1,3-butadiene  	Common air pollutant; found in vehicle exhaust 
Acrylamide  	Fried foods 
Benzene  		Common air pollutant; found in vehicle exhaust 
Perfluorooctanoic acid  Used in manufacture of Teflon 
Styrene  		Used in manufacture of plastics; found in
carpets, adhesives, hobby supplies 
Vinyl chloride  Used almost exclusively by the plastics industry to make
vinyl 
1,1-dichloroethane  	Industrial solvent; also found in some consumer
products such as paint removers 
Toluene diisocyanate 	Used in foam cushions, furnishings, bedding 
Methylene chloride  	Used in furniture polish, fabric cleaners, wood
sealants and other consumer products 
PAHs  		Diesel and gasoline exhaust 
PCBs  		Electrical transformers; banned but still in environment

Atrazine  		Widely used herbicide, particularly for corn 


Source: Silent Spring Institute 




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
Mail:          P.O. Box 1105, Richmond, VA  23218 (NEW!)
Location:  629 E. Main Street, Richmond, VA  23219
PH:         804-698-4028
FAX:      804-698-4032