From Our 2008 Archives

Formaldehyde Linked to Lou Gehrig's Disease

By Randy Dotinga
HealthDay Reporter

WEDNESDAY, April 16 (HealthDay News) — New preliminary research suggests that exposure to the chemical formaldehyde, present in a variety of workplaces, could greatly increase a person's chances of developing Lou Gehrig's disease.

The findings aren't definitive, and only a few thousand Americans are diagnosed with the condition — also known as amyotrophic lateral sclerosis (ALS) — each year.

Still, the study results deserve attention, especially since formaldehyde hasn't been considered an ALS risk factor before, said study author Marc Weisskopf, an assistant professor of epidemiology and environmental health at Harvard School of Public Health. "It's a result that we view as very intriguing and worthy of follow-up."

The findings were scheduled to be released Wednesday at the American Academy of Neurology annual meeting, in Chicago.

ALS progressively causes damage to the nerve cells in the brain and spinal cord. Patients lose the ability to control their muscles, and they typically become paralyzed. There's no cure for ALS, and treatments have limited value.

Weisskopf and his colleagues examined statistics from an American Cancer Society study of more than 1 million people who were followed for 15 years.

The researchers first examined the participants' responses in 1982 to questions about exposure to 12 different chemicals, including formaldehyde. Then they followed up between 1989 and 2004 to see what happened to those people.

The researchers found that 617 men and 539 women died of ALS during the study period. Only those who reported exposure to formaldehyde had a higher risk — 34 percent higher — of developing ALS.

Formaldehyde is used in the manufacture of a variety of products, including particle board, clothing, glues, cosmetics and shampoo. People who work in medical facilities and mortuaries may also encounter it on the job.

The pungent chemical has already been linked to higher rates of lung cancer and leukemia. It was not declared a probable human carcinogen at high exposure levels by the Environmental Protection Agency until 1987.

Those who reported more than 10 years of exposure to formaldehyde were almost four times more likely to develop ALS.

According to Weisskopf, the study design didn't allow him to estimate how many extra people may develop ALS because they are exposed to formaldehyde. However, he said there are only about 5,500 new cases in the United States each year.

Researchers have considered pesticides to be a possible cause of ALS, but formaldehyde hasn't been raised as a villain before, Weisskopf said. It's not clear how it might be linked to development of the disease, but Weisskopf said it could set off brain damage by increasing the "stress" caused by oxygen.

It's possible that other factors besides formaldehyde may be causing ALS in the study participants. Indeed, Weisskopf said the findings don't confirm a cause-and-effect relationship: "That's very hard to do. But it does provide an avenue to get more insight into the disease process, and it may give us insight that's helpful in determining other avenues to take."

Dr. Catherine Lomen-Hoerth, director of the ALS Center at the University of California, San Francisco, said it's too early for anyone to worry too much about the findings.

The research "means studies can be done in ALS rats or mice to see if formaldehyde worsens the disease process," she said, but, "I don't think we understand environmental factors very well, and in what way they affect disease processes."

"If we knew more about what causes ALS, we might know more about how formaldehydes and other chemicals might [play a role]," she added.

SOURCES: Marc Weisskopf, Ph.D., assistant professor, epidemiology and environmental health, Harvard School of Public Health, Boston; Catherine Lomen-Hoerth, M.D., Ph.D., director, ALS Center, University of California, San Francisco; April 16, 2008, presentation, American Academy of Neurology annual meeting, Chicago

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