Additional chemicals found leaching from common plastic: polypropylene, quaternary ammonium biocides, oleamide, pvc

[Guest guest]

" Ms. Sutton expressed concern that exposing people to extra oleamide

might alter brain function "

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Researchers raise alarm after chemical leak found in common plastic

MARTIN MITTELSTAEDT

ENVIRONMENT REPORTER

November 7, 2008

http://www.theglobeandmail.com/servlet/story/LAC.20081107.CHEMICAL07//TPStory/En\

vironment

Medical researchers at the University of Alberta say that two chemicals

leaking from plastic laboratory equipment were so biologically active

they ruined a drug experiment.

The inadvertent discovery could have wide-ranging consequences because

the chemicals causing the experiment to go awry were leaching from

polypropylene, one of the most commonly used plastics in the world.

Besides being found in scientific equipment, the plastic is used to make

everything from yogurt tubs to clothing.

The findings were so alarming to the researchers, from the university's

faculty of medicine, that they issued a warning yesterday in the journal

Science, alerting others scientists to the possibility that contaminants

from plastic ware in their laboratories could put experiments at risk.

Not enough is known about the two substances leaking from the plastic -

quaternary ammonium biocides and oleamide - to know what hazard, if any,

they might pose through exposure to consumer products made from

polypropylene.

" It's very difficult to say whether we should be worried from a health

point of view about this, " said Holt, the paper's lead researcher

and an assistant professor of pharmacology.

But Dr. Holt said that virtually all medical laboratories in the world

routinely use materials, such as bottles and tubing, made from the

polypropylene, putting their results at risk. " Scientists need to be

aware of this, " Dr. Holt said.

Other experts, though, said they were worried that plastics might be

leading to human exposures, with unknown effects.

" We simply don't want these chemicals getting into our bodies, " said

Sutton, senior scientist with Environmental Working Group, a

U.S.-based advocacy organization.

The group wrote to the U.S. Environmental Protection Agency last month,

objecting to an effort to loosen exposure standards for quaternary

ammonium compounds.

The Alberta researchers aren't the first to be surprised that chemicals

inadvertently leaking from some types of plastic can skew experimental

results.

During the early 1990s, researchers at Stanford University School of

Medicine in California found that bisphenol A leaking from a different

type of plastic, polycarbonate, caused experiments investigating

estrogen to run amok. Their discovery helped trigger a flurry of

research into the chemical.

Last month, Health Canada said it would place bisphenol A, which is now

considered a female hormone mimic, on the country's list of toxic

substances.

At the U of A, a team lead by Dr. Holt made their discovery while

conducting experiments on a human enzyme that is the target for drugs to

treat Parkinson's disease.

The researchers were trying to inhibit the activity of the enzyme with

ammonium chloride. They were surprised to find that even when they only

added one part per million of the ammonium chloride, an amount that is

so minute it was expected to have little effect, some mystery substance

was still blocking the enzyme function.

The team initially suspected contaminants in the chemicals they were

using, but eventually they determined that biologically active

substances were leaking from the plastic tubes they used to transfer

liquids in the experiment.

Using sophisticated testing equipment, they found that one of the

mystery chemicals was oleamide, a compound used to improve the fluidity

of molten plastic. Oleamide also occurs naturally in the human body, and

is found in the brain and blood.

The chemical is also added to other types of plastic, such as polyvinyl

chloride and low-density polyethylene.

Ms. Sutton expressed concern that exposing people to extra oleamide

might alter brain function.

" If we end up dosing ourselves with higher levels, this could disrupt

various processes. "

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