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MONDAY, Dec. 6, 2004 (HealthDayNews) --

Shampoo Ingredient Kills Rats' Brain Cells

By Steven Reinberg
HealthDay Reporter

The chemical, methylisothiazolinone (MIT), belongs to a class of compounds called.biocides.
These are used in the manufacture of many common household products and industrial
water cooling systems to prevent bacteria from developing.

According to the.National Institutes of Health.(news - web sites),
brands containing MIT include the shampoos.Head and Shoulders, Suave,
and.Clairol,.as well as.Pantene hair conditioner.and.Revlon hair color.

Aizenman said.he is concerned that without such.testing.it is not known.if, for example,
a pregnant woman.who is exposed to MIT could put her fetus at risk for.abnormal
brain development..People working directly with MIT are those most at risk, he said.

In earlier experiments with rat brain cells, Aizenman's team found that direct exposure
to MIT in concentrations like those found in hand cream was enough to kill neurons.
In the current series of experiments, also with rat cells, the researchers found that
a long exposure to low concentrations of MIT caused a malfunction in the ways
neurons communicate with each other.

"One of the things that this compound was very good at was preventing
neurons from communicating with other neurons,".he said.

Aizenman presented his findings Dec. 5 at the American Society for Cell Biology
annual meeting in Washington, D.C.

Whether long-term exposure to products containing MIT is dangerous is not known,
Aizenman said. "Can I say that these products are safe to use? No," he said.
"Can I say that these products are unsafe to use? No."

Aizenman believes that testing needs to be done to determine if MIT
is harmful to humans in the concentrations found in household products.

"It appears that the Environmental Protection Agency (news - web sites)
does.not.require neurodevelopmental testing,".Aizenman said........ç.Remarked in.Footnote 1 below.

"That is bothersome..Maybe there are substances that have made
it into general use that could be damaging to the nervous system.
Regulators need to take a hard look this and require more tests."

The work that Aizenman has been doing."is important in understanding
the things that people are.exposed to on a chronic, daily basis,"
said Beth Ann.McLaughlin,.an assistant professor of pharmacology at Vanderbilt University.

McLaughlin.added that.people using products containing MIT should be skeptical.
"There is a healthy dose of skepticism that needs to come when using
any products or being intensely exposed to any compound,".she said.
 

McEwen,.quoted below, is an employee  of a.chemical.products industry.

"These findings are expected,".said Gerald.McEwen,.vice president
for science at the.Cosmetic, Toiletry and Fragrance Association.
"MIT is a biocide. The purpose of it is to kill bacteria.
You would expect it to be detrimental to any type of cells."

McEwen.said that direct exposure to high concentrations of MIT will be irritating to the skin,
because it can damage skin cells. However, he doesn't believe that MIT poses any dangers
to consumers in the low concentrations found in household products.

"The ability of MIT to cause neurotoxicity has been studied,".McEwen.said.
In animals exposed to MIT, there has been no hint of neuro-damage,.......ç.Remarked in.Footnote 1 below.
because MIT affects only the cells it touches and.there is no way
for it to get into the bloodstream and go to the brain,.McEwen.said..ç.Rub.shampoo onto scalp.

"It can't get to your brain cells, period,".McEwen.emphasized..ç.Rub.shampoo onto scalp.

MIT has been approved as a biocide by the EPA,
which.looked at.the neurological effects,.McEwen.added.
This information was published by the.Cosmetic Ingredient Review,.....ç.Remarked in.Footnote 2 below.
an industry program that.reviews the safety.of cosmetic ingredients,.he explained.

However,.McLaughlin.remains.concerned:

"The quantity of compounds that we can make that make
..the quality of life wonderful, in the short term, is growing,".she said.

"But we are lagging in our understanding of what those compounds
..can do to our health and our children's health."