PCBs & Sunlight Cause Tumors

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Steven Powers MD.

 

Thursday, April 04, 2002 9:28 PM

PCBs & Sunlight Cause Tumors

 

 

http://www.nlm.nih.gov/medlineplus/news/fullstory_6747.html

 

 

PCBs And Sunlight Cause Skin Tumors

United Press International

 

Friday, March 22, 2002

 

 

NASHVILLE, Mar 21, 2002 (United Press International via COMTEX) -- Exposure to

PCB pollutants and ultraviolet rays could increase the risk of developing skin

cancer, researchers said in a study presented at a toxicology conference

Thursday.

 

Research conducted at the University of Illinois in Urbana showed

polychlorinated biphenyls or PCBs, an industrial waste product, mixed with

ultraviolet rays, produced non-malignant tumors in mice.

 

Scientists exposed hairless mice to soil from a Southern Illinois landfill dump

contaminated with PCBs and also polychlorinated dibenzofurans, a PCB byproduct,

for 77 days. Some of the mice then were exposed five days a week for 28 weeks to

solar ultraviolet radiation, which causes skin cancer in humans.

 

Study results showed the combination led to quick development of non-melanoma

tumors even on parts of the mice that had not been exposed to UV radiation. The

tumors did not turn into squamous cell carcinomas, the more deadlier type of

skin cancer. Mice exposed to PCBS, but kept out of the sunlight did not develop

these tumors.

 

By day 281 of the study, however, mice exposed to UV rays but not PCBs developed

double the number of skin tumors compared to mice exposed to the combination.

Researcher said it is possible polychlorinated dibenzofurans protected the skin

from tumors by thickening it.

 

" It shielded the UV light, that's our theory now, " researcher Larry Hansen, a

professor of toxicology, told United Press International. " We haven't tested

this, but they (the PCBs) definitely thickened skin. "

 

The findings were presented Thursday at the Society of Toxicology meeting in

Nashville, Tenn.

 

Researchers said PCBs are found just about anywhere, in the land, water, air and

even food. Concentrated regions of PCBs include the Great Lakes, Hudson River

and St. Lawrence River. One of the biggest sources for human exposure to PCBs is

eating fish from these areas, Hansen said.

 

Scientists also know PCBs weaken the immune system, which might contribute to

making organisms more vulnerable to cancers.

 

" PCBs, some of them, suppress the immune system, " Hansen said. " UV light also

upsets the immune system. The immune system is important in picking up bad cells

that may become cancer so they can both initiate cells to change into potential

cancer cells. "

 

Hansen added, " This is kind of a pilot study. We were surprised how definite the

results were. We expected a trend, but it's really clear cut. "

 

Dr. Allan Oseroff, chairman of the joint Dermatology Department at Roswell Park

Cancer Center and also the University of Buffalo, both in Buffalo, N.Y., said

scientists have known PCBs can cause mutations in cells.

 

" PCBs can cause what's called oxidative stress as can ultraviolet light and both

of those can cause mutations in the cells, " Oseroff told UPI. He said the

findings of the research weren't surprising.

 

What is a concern, he said, is how much PCBs does it take to produce a toxic

effect in humans?

 

" We don't know for certain if there's such a thing as a safe amount of PCBs, " he

said.

 

(Reported by Katrina Woznicki in Washington)

 

 

 

Copyright 2002 by United Press International.

 

--

 

 

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S. Powers MD.

 

 

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