Is plastic dangerous?

February 26, 2008 12:00:00 AM PST
If you're afraid of microwaving plastic, or feeding your infant with a plastic baby bottle, it's probably because you've heard news reports about the "toxic chemicals" contained in plastic.

But those reports have been based on the research of a very small subset of scientists, whose work is now being called into question by independent toxicologists and regulatory agencies around the world.

Scene from "The Graduate:" "I want to say one word to you. Just one word. Yes, sir. Are you listening? Yes, I am. Plastics. Just how do you mean that, sir?"

Forty-one years later, plastic is still a buzz word.

"I hear that plastics can be a contributor to cancer and I don't want to do that to my child," said mother of one Laura Pacchini.

A recent study called "Baby's Toxic Bottle" and put together by a coalition of activist groups has parents questioning the safety of polycarbonate plastic and the chemical in it, Bisphenol-A or BPA.

"When I heard the research I was very concerned," said a parent.

Since the 1930s, BPA has been recognized as an endocrine disruptor-- the chemical mimics estrogen and some claim it's linked to a host of problems.

"These things range from causing obesity and insulin resistance which is a pre diabetic condition as well as its effects on reproduction, including infertility and pre cancerous lesions," said NRDC Science Fellow Dr. Sarah Janssen, Ph.D.

But what does the bulk of the research really show. And how does what happens in lab animals translate to humans?

Scientists agree BPA is released into what we eat and drink. It lines our water tanks and pipes. The inside of cans of fruit, vegetables, even soda.

It's also released from hard plastics, from baby bottles to water bottles.

But the amount that leaches out is extremely small, about a thousand times less than what the Environmental Protection Agency deems safe.

Dr. Sarah Janssen, with the National Resources Defense Council points out that "safe number" is more than 20 years old.

"It's a number that was established long before the science around some of these recent concerns was done," said Dr. Janssen.

"It's an old number, on lifetime carcinogenicity studies in rats and mice, they were looking f tumors, they weren't looking for, which is the current controversy about developmental toxicology, reproduction toxicity," said toxicologist Calvin Willhite, Ph.D.

Toxicologist Calvin Willhite is with California EPA. He recently completed a two year BPA risk assessment on his own time with "NSF International" -- a not for profit, public health and safety company.

The goal: to sift through the more than 4,000 studies on BPA, carefully analyzing the scientific data and determining a more current "safe number" for humans -- what's known as a reference dose.

"You want to find a dose where it doesn't do anything," said Willhite.

Then he says, divide by uncertainty factors, making that number even smaller.

Ninety-nine percent of our exposure to BPA comes from eating or drinking it, but toxicologists explain when it's processed through the lining of our gut and liver, a sugar is attached.

It's detoxified and is no longer an endocrine disruptor -- it's excreted from our bodies, humans metabolize it more efficiently than rats. But when low doses of Bisphenol-A are injected in lab animals, the results are quite different and Whillhite cautions, not relevant.

"We must go back to the route of exposure. If I inject it in my brain, or if I inject it in my veins, or if I inject it in my skin, I can demonstrate your endocrine disruption, I cannot demonstrate it through reproducible oral studies. It doesn't happen," said Willhite.

"This is why it's so important to have independent scientists look at the bulk of the data and understand, because environmental groups could also be misrepresenting the science, they could be very convinced by a fringe group of scientists, they could themselves believe in their hearts that chemicals are bad without necessarily understanding the toxicology, the science, the epidemiology the statistics behind what those studies are," said STATS Director of Research Rebecca Goldin, Ph.D.

Professor Rebecca Goldin is Director of Research for Statistical Assessment Services or STATS -- a non-profit, non-partisan organization dedicated to the responsible use of scientific data and statistics by the media.

She points to the recent "toxic baby bottle" study --which wasn't reviewed by independent scientists. It showed very small amounts of BPA leaching into bottles under extreme conditions, when they were heated to 176 degrees for 24 hours.

"The worst case scenario is when some of the soap in the bottles kind of cakes on them and then you heat these bottles at very high levels, and you don't notice it and you don't rinse it out, and the baby drinks all that and does it all day long. What you find is still that amount is still about three-percent of what the tolerable daily intake is established by the European Food Safety Authority," said Goldin, Ph.D.

In fact, the European food safety authority is known for being much more "risk adverse" than the FDA -- it operates under the precautionary principle which means scientific consensus isn't needed to take action.

Two years ago it reviewed Bisphenol and found:

"Low dose effects of BPA in rodents have not been demonstrated in a robust and reproducible way"... and based on the current science, it actually raised its safe number for BPA-- believing it to be less toxic than previously thought.

But the NRDC and Dr. Jannsen are concerned by the influence of the plastic industry and favor research by academia.

"The majority of the studies which have found no effect were funded or done by industry which has a vested interest in keeping this chemical available in the market," said Janssen.

"That in fact is true, because the U.S. EPA is not going to fund the studies," said Willhite.

But Willhite points out the contract labs in which those studies are conducted are regulated by auditors and must maintain what's known as GLP -- good laboratory practices.

"The main thing people should keep in mind, in universities, they don't have good laboratory practices, they don't have auditors like that, not in basic science laboratories," said Willhite.

The independent analysis recently completed by Willhite and NSF is published in February's Journal of Toxicology and Environmental Health. It establishes a new "safe number" for BPA -- a reference dose that's more rigorous than the current one provided by the EPA and the European Union.

Environmental groups, though, see no safe amount for vulnerable populations.

"We take the position that while the jury might still be out on the science on how dangerous this chemical is, it's an easy exposure to avoid," Dr. Janssen.

But Professor Goldin points to the overwhelming weight of the scientific evidence.

"What I would advise parents is don't worry about your baby bottles, if your worried about plastics, keep plastic bags away from children, that's something we know has a very definite risk, 25 children about every year die of suffocation from a plastic bag," said Goldin, Ph.D.

ABC7's Carolyn Johnson: "Why shouldn't this be a concern for parents?"

"The concentration that's in there is infinitesimal, and it's at least 500 and closer to a thousand times less than what you can calculate from the most rigorous studies that we have available," said Willhite.

The EPA is in the process of re-working its safety standards for BPA. California, Massachusetts and Canada have requested the new risk assessment from NSF.

For specific links to the organizations or for more information on the research, click on The Back Story.

  • Center for the Evaluation of Risks to Human Reproduction, Panel Report on BPA


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