Silicone breast implants absorb environmental toxins from the body, and they could become a new tool for studying a link between pollution and cancer.

That’s according to a pilot study published in the journal Environmental International by Oregon State University chemist Kim Anderson.

“These breast implants — there are tens of thousands — are being disposed of as waste,” said Anderson, a professor of environmental and molecular toxicology. “They could be a resource to understand the contaminants and chemical load in women. They could be a huge resource for understanding the actual levels in our body.”

Scientists have known for decades that some types of pollutants accumulate in fatty tissue. Silicone’s molecular structure is similar to fat, so showing that it absorbs chemicals in the same way could be beneficial to future environmental health research, said David Kalman, an environmental chemist at the University of Washington.

Other research has implicated the banned pesticide DDT and a byproduct of its breakdown in the environment, DDE, in breast cancer, Anderson said. Knowing that silicone implants could serve as a proxy for fatty tissue, which is logistically challenging and expensive to collect, Anderson said she hopes they’ll be used in breast cancer research. “Certainly that’s where we’d want to start going. We could look at lots of people, inexpensively.”

In the pilot study, Anderson looked at just eight discarded implants, which she obtained from an Oregon Health & Science University doctor in 2010. She collected no personal or demographic information on the women who’d worn the implants, but because of the link to humans, she took the step of having the experiment reviewed by an ethics panel as if it were going to include human subjects.

In another experiment, Anderson’s lab found that the silicone bracelets people wear in support of various causes could be used to collect information about exposure to environmental toxins.

Because of that research, the Environmental Defense Fund is trying to recruit thousands of people to wear chemical-absorbing silicone bracelets and then submit them for analysis.

“The presumption is that what we test in the wristband is available to get into the body,” Anderson said. “This is actually stronger,” she said of the breast implants. “The only way a chemical could get into the breast implant is if the chemical were already in the body.”

The implant study had two parts. First, the discarded implants were screened for about 1,400 chemicals found in the environment. Researchers also screened unused silicone “sizers.” They found that the discarded implants contained 14 common compounds used in foods and personal-care products, commercial and industrial products and pesticides.

The most common chemical detected was caffeine, which was in all eight samples. The second-most common compound, found in five samples, was the DDT byproduct.

Mouse implants

The researchers also used mice to see how silicone implants would react to controlled chemical exposure. The mice also allowed them to compare the concentration of chemicals in silicone to the concentration in fatty tissue.

The researchers surgically implanted tiny silicone discs into anesthetized laboratory mice. The mice received as much silicone, in proportion to their body mass, as would be used in a range of typical human breast implants or prosthetic reconstructions.

Then the mice were given two compounds, the DDT byproduct and PCB 118, which was once widely used in industry and is a probable carcinogen. Both chemicals accumulate in fat.

A group of control mice received silicone implants but no chemicals. A third group received chemicals but no implants.

Anderson has been studying passive environmental sampling for 20 years, but she said the idea of looking at breast implants originated with one of her doctoral students. The question was whether the implants would behave the same as other types of passive samplers, once they’re in the fatty environment of the body. “They do sequester chemicals,” she said.

“So now of course there’s other hypotheses,” Anderson said. “How does this affect potential health issues?”

Anderson is interested in the tie to breast cancer because other researchers have found that women who have breast implants also have lower rates of breast cancer.

After reading Anderson’s article, Kalman said he doesn’t think the Oregon State team found high enough levels of contamination in the mouse implants to suggest that they somehow protect the body. “The amount that’s going into the implant is too little to affect what remains in the fat,” he said.

Anderson pointed out that the silicone discs were removed from the mice after nine days. “Longer times before removing the silicone would likely increase the concentration in the silicone,” she said in an email.

Studying pollution in the human body is not easy. For about 20 years, the U.S. Environmental Protection Agency ran a program that collected fatty tissue samples from people who’d died or undergone elective surgery, Kalman said. That program, the National Human Adipose Tissue Survey, showed that levels of PCBs in humans declined after the chemicals were banned, he said.

The program was discontinued, however, because it didn’t turn out to be as useful to the research community as the EPA had hoped, Kalman said. One of its main limitations was that because tissue was collected opportunistically, the results couldn’t apply to the population at large, he said.

A study of silicone breast implants would have the same limitation, Kalman said. “It’s a glimpse of something, but how the something applies to the population as a whole is always going to be a question.”

—Reporter: 541-617-7860, kmclaughlin@bendbulletin.com