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Chemicals from test tubes may be fouling experiments, scientists say
Last Updated: Thursday, November 6, 2008 3:12 PM ET
CBC News

Researchers in Alberta have discovered that two chemicals used in the making of plastic test tubes and other lab storage units can leach into experiments, interfering with some results.

University of Alberta pharmacology researcher Andrew Holt said previous research suggests the leaching compounds, and their presence in other plastics, do not pose a health hazards, as do other contaminants such as bisphenol A.

But the findings, published in Thursday's issue of the journal Science, could have an indirect impact, as they raise the prospect that the leaching compounds may have compromised thousands of medical and pharmaceutical experiments.

At best, such interference would introduce extraneous or scattered data, forcing experimenters to waste time and money retesting experiments. And at worst, it could mean papers could have been published based on faulty results, or that current research might be impacted by those results.

Holt said he doesn't have any examples of papers that might have been published or experiments that may have been delayed by the leaching. But the sheer amount of work done in health research suggests the problem could be widespread.

"We do know that of our less than 20 research groups here at Alberta, at least three have experiments whose results could be affected by these compounds," he told CBC News.

"There are tens of thousands of research labs doing life sciences experiments around the world," he said. "It seems reasonable to suggest a percentage of these may be affected as well."

Two compounds affected results

Holt said while the scientific community has generally accepted that using plastic equipment reduces the likelihood of experimental success, few efforts have gone into identifying the substances at the root cause of introduced errors.
The two compounds, a disinfectant called DiHEMDA and a lubricant called oleamide, are both used in the manufacturing process of disposable plastic labware, including test tubes, to improve their sterility and reduce stickiness, respectively.

The researchers made their discovery while attempting to assess the effects of ammonium chloride on the activity of a human enzyme, called monoamine oxidase B, or MAO-B. While the results showed the ammonium chloride had a very weak effect on the enzyme, the results varied widely during each test.

After all other possibilities had been exhausted, the researchers came to the test tubes themselves, and using mass spectrometry they were able to isolate the two leaching compounds, both of which, as it turned out, were strong inhibitors of the enzyme.

Further study revealed inconsistencies in the appearance of the chemicals in the plastic equipment. For example, 1.5 ml test tubes from one company had no effect on the experiments, while 0.5 ml test tubes from the same company (but a different manufacturing plant) had a potent effect on the enzyme.

Money would have been wasted

Holt said he estimates that the research group spent over six months of solid work trying to determine the cause of the anomaly at a cost of $60,000 in federal funding through a Canadian Institutes of Health Research grant

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