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Chemical in Plastic Test Tubes Botched Experiments, Study Says

By John Lauerman

Nov. 6 (Bloomberg) -- Plastic test-tubes and dishes used in laboratories are made with chemicals that can disrupt reactions and could be botching experiments worldwide, scientists said in the journal Science.

The test-tube chemicals, a disinfectant called DiHEMDA and a lubricant called oleamide, can migrate out of plastic into experimental fluids and stop proteins from behaving normally, said Andrew Holt, a professor of pharmacology at the University of Alberta in Edmonton and an author on the study.

Laboratories all over the world use plastic tubes, pipettes and dishes made by companies such as Thermo Fisher Scientific Inc., Sarstedt AG and Eppendorf AG, Holt said. The equipment was the last thing expected to lurk behind the odd results he was getting in his effort to find drugs for Parkinson's disease, the scientist said in a telephone interview.

``We thought this was a nuisance for us, we didn't realize how widespread it could be,'' he said. ``This is an issue that could affect many branches of science worldwide.''

Executives from makers of the equipment--closely held Sarstedt, based in Numbrecht, Germany; Eppendorf, based in Hamburg, Germany, and Thermo Fisher in Waltham, Massachusetts-- didn't immediately return calls seeking comment. Thermo Fisher fell $2.85, or 7.1 percent, to $37.32 at 1:14 p.m. in New York Stock Exchange composite trading, and have lost 30 percent this year before today.

Parkinson's Study Confounded

Holt works with an enzyme called monoamine oxidase B, or MAO-B, which is thought to be involved in Parkinson's disease, a nerve disorder that affects as many as 1 million Americans, according to the Parkinson's Disease Foundation. Enzymes speed reactions in the body, and Holt was testing chemicals that he thought would block MAO-B's activity.

Even at low concentrations, the drug he was experimenting with had far more effectiveness at blocking the enzyme than expected. It was only after going through every other aspect of the experiment that Holt realized that there were no abnormal results in a part of the experiment that had been performed in a glass receptacle.

``We were stunned at the degree of effect we were getting on our enzyme from a solution in contact with a single plastic tube,'' he said.

By washing clean labware with solvents, Holt was able to isolate the chemicals that were moving from the test-tubes into the materials he was experimenting with. Some of them were better at blocking MAO-B than the drugs he was working with.

Solvents Potent

``Some of these were some of the most potent inhibitors of the compound we work on that have ever been described,'' he said.

The chemicals may be affecting many other scientists' experiments, Holt said. In his own department, there are three other lab leaders who suspect their results have been skewed by test-tube chemicals.

``We looked at every other possible variable that might have caused what we were seeing,'' Holt said yesterday. ``We were banging our head against the wall. Finally, we realized that the plastics must be involved in the issue.''

To contact the reporter on this story: John Lauerman in Boston at jlauerman@bloomberg.net.

Last Updated: November 6, 2008 14:00 EST