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MU researchers find more evidence against bisphenol A

Monday, June 13, 2011 | 12:01 a.m. CDT; updated 12:54 p.m. CDT, Monday, June 13, 2011

COLUMBIA — MU scientists warn that there is likely more bisphenol A circulating in the human bloodstream than previously believed.

In a new study, Cheryl Rosenfeld and a group of researchers at the Bond Life Sciences Center were the first to simulate a realistic intake of BPA in people through a BPA-supplemented diet fed to mice. The scientists found significantly higher levels of the chemical in animals exposed to BPA through regular diet than in the subjects that ingested a one-time dose.

Scientists in various fields have warned that the effects of BPA — an endocrine disruptor commonly found in household plastics — could cause a catalog of health problems such as reproductive disorders, learning and memory difficulties, and problems with the immune system.

“It can affect estrogen, thyroid and testosterone function, and might cause genetic mutations,” Rosenfeld said.

Despite an ever-growing list of studies demonstrating adverse effects of the chemical, BPA proponents assert there is not enough evidence to discontinue or even issue warnings on the chemical. These arguments, Rosenfeld said, are bolstered by one-dose studies that don't reflect human intake of BPA through normal diet.

The MU study is groundbreaking because previous research had used unrealistic conditions to test the effects of BPA. Consequently, human exposure was presumably underestimated.

“A previous study administered a single, one-time, liquid-dose exposure,” Rosenfeld said, which did not mirror the way people accumulate BPA by exposure to small amounts of the chemical on a regular basis in food.

The team instead created a mouse feed laced with radioactive BPA. After consuming the diet for a week, researchers found the biologically active BPA had accumulated in the mice’s systems, and was significantly higher than the measurement done after mice ate the feed for 24 hours.

The study also showed that the initial increase of BPA in the bloodstream was greater when administered through diet — akin to human intake.

“The liver has to metabolize BPA,” Rosenfeld said. She explained that BPA is introduced to the bloodstream quicker when paired with food, because the liver has to handle the food taken in as well as the chemical.

“This route of exposure potentially overwhelms the capacity of the liver to metabolize the food and the foreign substance,” she said.

Rosenfeld said this study and others that reflect realistic human exposure should be brought to the table in the heated BPA debate that's prompted legislative action and caused some manufacturers to seek out alternatives.

Rosenfeld said she hopes policymakers consider her findings when dealing with legislation to reduce and potentially ban BPA production.

“I would like them to become aware of these studies,” she said. “Single-time point measurements are probably not the most accurate method to measure BPA exposure in humans and animal models.”

BPA is widely used to harden many common plastics. It is rough and durable, and additionally used as a relatively cheap coating inside of almost all food and beverage cans.

More than 8 billion pounds are produced every year, and the study notes that more than 90 percent of people in the U.S. have “measurable amounts of BPA in their bodies.”

Rosenfeld said pregnant women in particular should take measures to reduce their exposure to BPA.

Babies have “even less ability to metabolize BPA and it can disrupt the growth of organs that are normally governed by sex steroid hormones,” she said. “Even sometimes low-dose exposure to BPA can lead to striking effects.”


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Comments

Mark Foecking June 14, 2011 | 8:06 a.m.

"The team instead created a mouse feed laced with radioactive BPA. After consuming the diet for a week, researchers found the biologically active BPA had accumulated in the mice’s systems, and was significantly higher than the measurement done after mice ate the feed for 24 hours."

If the concentration in the feed were that same for both groups, you'd expect to see higher levels after a week than after 24 hours, simply because the dose is seven times higher. This of course assumes a relatively long biological half life (several to 10's of hours or more). I imagine they did take this into account, but it's not clear from the article.

My understanding is that it's fairly easy to avoid significant exposure. If you don't use polycarbonate or PVC plastics, eat few or no canned foods or beverages, and don't handle BPA containing cash register receipts, you won't get much of the chemical.

Interestingly, BPA is a monomer used in epoxy resins. The counters at the information booth at the new City Hall addition are an attractive rock/recycled glass material cast in an epoxy-like material. I wonder if these counters contain a lot of BPA?

DK

(Report Comment)
Paul Allaire June 14, 2011 | 11:11 a.m.

So let's eat some epoxy paint, anyone?

Epoxy is a fairly hard and watertight substance. Also, I doubt anyone is going to cook a meal on the counter or even drop their food on it. Regarding your suggestions for avoiding it, I would think that you would need to avoid bottled water, soda in any container, beer that is not in glass containers including that which is poured from a keg, anything in a can, and anything in a plastic jar or bag, such as almost everything you buy at a grocery store. Additionally you might consider where the food was stored before it was last packaged. You might want to examine the cooler or the make line at your preferred food bistro.
And good luck not handling those receipts. They are very common. I know them because they have a remarkable way of becoming unreadable after a couple years, often voiding any guarantee that accompanied the product it was for. At the least, they should ban the receipts.
Do you really think they gave the one group of rats seven doses and the other one? I mean... people ARE stupid, but it IS a university. I don't know if it's possible to get several science majors together and produce a result THAT stupid. But then I AM continually surprised at what people can do. Stop defending every toxic chemical on the planet.

(Report Comment)
Ellis Smith June 14, 2011 | 1:32 p.m.

"...people ARE stupid, but it IS a university."

So, are we supposing that because it's a university stupid things aren't capable of happening?

Maybe we should apply the same logic to our federal government, because we all know that the federal government NEVER does anything stupid.

(Report Comment)
Paul Allaire June 14, 2011 | 2:02 p.m.

But they're student's after all. They haven't got to the federal level. They're still working on killing the first half of their brain cells.

I have been disgusted by the apparent leaps of logic made by various elements of the science community numerous times only to later find that the problem was not the scientists but rather the communication skills of the journalist. Perhaps we should let journalism tend to journalism and let science tend to science.

And you do make an excellent point. Quite a bit of stupidity happens at the University. It seems to be directed from inside.

(Report Comment)
Paul Allaire June 14, 2011 | 2:08 p.m.

And wow. Look at my grammar error.

(Report Comment)
Ellis Smith June 14, 2011 | 3:11 p.m.

"Quite a bit of stupidity happens at the University." Are you referring to that collection of buildings located south of downtown Columbia, or to UMKC, or to UMSL, or to MS&T, or to University of Missouri System as a whole? I think your comment might apply to all of those entities, but maybe more to some than to others.

Or maybe it might it apply to American public and private universities IN GENERAL?

(Report Comment)
Paul Allaire June 14, 2011 | 4:15 p.m.

I believe that if I had some kids I would push for them to get enrolled before they were old enough to drive. There would be less chance of their being disillusioned by the time that they should graduate. That decision would be regardless of what campus I lived near and despite the fact that much of my viewpoint comes from experiences on or around the local colleges.

There is quite a bit of intelligence at the same. I suppose that the reason I remark on the stupidity is that it often stands out with such a stark contrast. And of course, on a bad day it can appear to be the only thing visible.

(Report Comment)
Mark Foecking June 15, 2011 | 3:15 a.m.

Paul Allaire wrote:

"I doubt anyone is going to cook a meal on the counter or even drop their food on it."

I've seen kitchen counters made of this material. People touch it all the time. It was just an observation that those counters at City Hall might not be as environmentally benign as they hoped.

From:

http://www.hhs.gov/safety/bpa/

"In general, plastics that are marked with recycle codes 1, 2, 4, 5, and 6 are very unlikely to contain BPA. Some, but not all, plastics that are marked with recycle codes 3 or 7 may be made with BPA."

#1 is bottled water and soda containers (PETE). 2 and 4 are polyethylene (milk containers, and most types of cling wrap). #5 is polypropylene (plastic storage containers).

#3 and #7 are PVC and (in many cases) polycarbonate, respectively. Avoiding these will avoid the bulk of BPA exposure (also food and beverage cans)- you may not be able to get rid of all of it, but you can get rid of most of it.

Paul Allaire wrote:

"Do you really think they gave the one group of rats seven doses and the other one?"

No, I don't. It was more of a comment on the way the story was written. Look at the third sentence in my paragraph.

"Stop defending every toxic chemical on the planet."

I'm really just pointing out that some of these chemicals are very useful, and were introduced to solve problems with earlier materials. Everything has a risk vs. benefit - everything.

We felt it better to ban DDT than to simply change the way we use it, and after malaria came raging back, we rethought the balance of risk, and simply changed the way some countries use it.

It's less clear whether the use of BPA outweighs the risk (although the risk to most people seems miniscule compared to other risks we live with every day). Often this debate is couched it "evil giant corporation" rhetoric, when in reality, consumers have a lot of control over their exposure to pretty much anything. What we can't do is remove the risk from everything without giving up a lot of desired activity also.

DK

(Report Comment)
Paul Allaire June 15, 2011 | 12:35 p.m.

Thanks for the useful information about the plastic numbers. I had erroneously thought that soda came in PVC bottles. I suppose nobody is really that concerned about the individuals who drink 20 some cans of beer a day because they have other health issues and obviously aren't that concerned. However, the majority of us do eat canned food from time to time, whether it be at home, school, work, or in a fine dining establishment. Often this is not a matter of choice. A coated can is probably better than an uncoated one and a substitute may be hard to find, but that appears to be what is needed. Let's hope the next solution won't also be a problem. My thought is that it won't be that hard. I see a lot of cans with the inside painted and some that appear to be plated with what looks like brass. The latter are at least a hundred times more resistant to corrosion than the average can. Of course, I have no idea what is on top of that metal.

And I'm standing by my opinion about those receipts. They've got to be the biggest scam out there. Imagine buying a lot of hardware to upgrade a house and then when it comes time to write off the expenses after selling it you find that you have a box full of blank paper. Not good. It's like writing a check with disappearing ink.

(Report Comment)

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