Scientists from the University of California, Davis report that quaternary ammonium compounds (quats)—antimicrobials found in household products—inhibit mitochondria and cellular estrogenic functions. Their study is being published online in Environmental Health Perspectives.

According to the researchers, toothpastes, mouthwashes, lozenges, nasal sprays, eye drops, shampoos, lotions, intravaginal spermicidal sponges, and household cleaners all contain quats.

“Disinfectants that we are putting on and in our bodies, and using in our environment, have been shown to inhibit mitochondrial energy production and the cellular estrogen response,” explained biochemist Gino Cortopassi, Ph.D., in the UC Davis School of Veterinary Medicine. “This raises concern because exposure to other mitochondrial-inhibiting drugs, such as rotenone and MPTP (1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine), is associated with increased risk for Parkinson's disease.”

The study focused on 1600 compounds and drugs associated with household and pharmaceutical products and examined a variety of aspects of mitochondrial functioning. The team discovered that that quats inhibited mitochondrial function and estrogen signaling.

“Because exposure to quats is also interrupting the sex hormone estrogen response in cells, it could also potentially cause reproductive harm in animals or humans. Others have shown that quats cause reproductive toxicity in animals,” added Dr. Cortopassi.

While UC Davis scientists carried out an in vitro study, researchers at Virginia Tech several years ago reported that quat exposure through a laboratory disinfectant caused reproductive toxicity and reduced fertility in mice. They also recently demonstrated a link between quats and neural tube birth defects in both mice and rats.

“Our study in cells provides a mechanism for their observations in laboratory animals,” said Sandipan Datta, Ph.D., a postdoctoral scholar in Dr. Cortopassi's laboratory. “They demonstrated that quat exposure caused reproductive toxicity in both females and males. The antiestrogenic effects we see in cells could explain the female reproductive toxicity they observed, such as less estrus cycles and lower breeding rates.”

According to Dr. Cortopassi, the antiseptic triclosan and similar products were taken off the market when it was learned in animal studies that they appeared to impair muscle function.

With a number of companies planning to replace triclosan with quats, Dr. Cortopassi points out that this might not be the safest way to go. He and his colleagues are moving to additional work with animal models to find out how these chemicals may accumulate in tissues and to see if exposure to quats impacts health and disease in humans.

“This paper adds to the growing number of studies which find that quats may not be as safe as previously believed,” said Terry Hrubec, DVM, Ph.D., associate professor at Edward Via College of Osteopathic Medicine-Virginia, and not a co-author on this study. “The fact that six out of the 10 most potent mitochondrial inhibitors were quats shows that this class of chemicals likely affects living systems. The results from this study are concerning because almost everyone is exposed to quats on a regular basis.”

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