OT: CHEMICAL IN PLASTICS IS TIED TO PROSTATE CANCER

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From: Los Angeles Times, Jun. 1, 2006

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CHEMICAL IN PLASTICS IS TIED TO PROSTATE CANCER

Bisphenol A, found in baby bottles and microwave cookware, permanently

altered genes in newborn lab rats, a study finds.

By Marla Cone

Linking prostate cancer to a widespread industrial compound,

scientists have found that exposure to a chemical that leaks from

plastic causes genetic changes in animals' developing prostate glands

that are precursors of the most common form of cancer in males.

The chemical, bisphenol A, or BPA, is used in the manufacture of hard,

polycarbonate plastic for baby bottles, microwave cookware and other

consumer goods, and it has been detected in nearly every human body

tested.

Scientists and health experts have theorized for more than a decade

that chemicals in the environment and in consumer products mimic

estrogens and may be contributing to male and female reproductive

diseases, particularly prostate cancer.

The new study of laboratory rats suggests that prostate cancer, which

usually strikes men over 50, may develop when BPA and other estrogen-

like, man-made chemicals pass through a pregnant woman's womb and

alter the genes of a growing prostate in the fetus. One in every six

men develops prostate cancer, a rate that has increased over the last

30 years.

Researchers at the University of Illinois at Chicago and the

University of Cincinnati exposed newborn rats to low doses of BPA and

found the structure of genes in their prostate cells was permanently

altered, a process of reprogramming in early life that promotes cancer

in adulthood. One key gene was switched on, producing too much of a

cell-damaging enzyme that has been detected in cancerous prostate

cells but not normal cells.

Also, as the rats aged, they were more likely than unexposed animals

to develop precancerous lesions, or cellular damage, in the prostate

that have been known for years to lead to prostate cancer in humans.

" The present findings provide the first evidence of a direct link

between developmental low-dose bisphenol A... and carcinogenesis of

the prostate gland, " according to the researchers. Results from the

team, led by Gail S. Prins, associate professor of andrology at the

University of Illinois at Chicago, and Shuk-mei Ho, chair of

environmental health at the University of Cincinnati, are reported

today in the journal Cancer Research.

Exposure to the chemical " may provide a fetal basis for this adult

disease " in humans, the report said.

Dr. Sokol, a USC medical school professor who specializes in

male hormone research, called the study " cutting-edge.male hormone re

added to a growing body of research, called epigenetics, that

suggested environmental chemicals could alter how DNA sequences turned

on and off in a fetus, permanently imprinting the genes of a child and

sensitizing him or her to disease in adulthood.

Such findings could have major implications for human disease and

could, in part, explain why the prostate cancer rate has surged. BPA,

used for about half a century, is a key building block in the

manufacture of polycarbonate plastic and ranks among the world's most

widely used industrial chemicals.

Prins, Ho and other researchers cautioned that the study was conducted

on rats, which sometimes reacted differently to chemicals than humans

did. Replicating the work in humans is virtually impossible because 50

or more years usually pass from exposure in the womb to the onset of

prostate cancer.

" You can't say from the results of this study that this is going to

affect humans, " Sokol said. But she said the results were in line with

previous animal research that showed chemicals could induce genetic

changes that altered sperm and other reproductive functions. The

prostate gland, which develops in human males when they are fetuses,

is extremely sensitive to natural estrogen. As a result, scientists

have long theorized that prostate cancer could be increasing in men

because of their exposure to estrogen-like chemicals in the womb.

Unlike carcinogenic chemicals that can cause profound damage to DNA,

BPA seems to inflict subtle changes that are passed from one

generation to the next, Sokol said.

" The big focus today is whether or not environmental toxicants will

induce heritable changes in gene function.... In other words, is there

something that happens to alter genes without actually altering the

genetic code? " asked Sokol, who studies the effects of chemicals on

sperm. " This [new study] is cutting-edge research in this field and

the role that environmental toxicants may play in altering the

genetics of exposed offspring. "

Steve Hentges, a representative of the American Plastics Council,

called it " fascinating research, a good piece of research " that should

be studied further. But he said the " real question is what does this

mean for human health, " because there are too many limitations in the

study for it to apply to humans.

" No one has actually observed prostate cancer after any treatment with

BPA, " he said.

The study's authors said the animals developed the precancerous

lesions and genetic changes when exposed to low concentrations of the

chemical similar to the amounts found in human blood and fetuses. But

Hentges said the rats were injected with doses 100 to 1,000 times

higher than the most recent human testing done by federal officials in

2004.

In recent years, evidence has been building that BPA causes changes in

the hormones and reproductive tracts of male and female animals. Lower

sperm counts, decreased testosterone and enlarged prostates were

reported in male animals, and early puberty and disrupted hormonal

cycles in female animals.

Of more than 100 studies that examined low doses of the chemical, 94

funded by government agencies found harmful effects in lab animals,

and 11 funded by industry reported no effects, according to a 2005

review by Frederick vom Saal of the University of Missouri.

Polycarbonate, which cannot be manufactured without BPA, is a clear

and shatter-free plastic. In addition to beverage bottles, utensils

and food packaging, it is used in automobiles, medical equipment and

compact discs.

Small amounts of the chemical can leach from plastic containers,

especially when heated, cleaned with harsh detergents or exposed to

acidic foods or drinks. It also is used in children's dental sealants

and as a resin lining metal food cans.

Last year, the California Legislature considered a bill, introduced by

Assemblywoman Wilma Chan (D-Oakland), that would have banned

children's products that contained BPA or other plastic compounds

called phthalates. It died in an Assembly committee after sparking a

scientific debate and intense lobbying by the plastics industry.