The cost of clean: Disinfectants cause birth defects in baby mice.
Ordinary cleaning compounds—used in ordinary amounts—create long-lasting risks of spinal and brain defects in a lab study.
Common cleaners used in homes, hotels and hospitals cause birth defects in fetuses, according to a new study of mice.
In some cases just being in the same room with the chemicals was enough to increase birth defects in the mice. The scientists involved say they can't draw any conclusions for exposed humans but “animal studies are the gold standard for predicting human health effects," said Terry Hrubec, professor and researcher at Virginia Tech University and lead author of the study published today in the journal Birth Defects Research.
The mice didn't even need to be directly dosed –just using disinfectants in the rooms led to increased birth defect rates.People are exposed “every day to these chemicals," she added.
The chemicals, called quaternary ammonium compounds, or “quats", are often found in cleaning products and disinfectants used in people's homes as well as at hotels and hospitals because they're efficient at cleaning bacteria and viruses.
Quats are also found in some laundry detergents, treatments for swimming pools, food preservatives in packed produce, and personal care products such as shampoos and conditioners.
Industry representatives have pushed back, saying all cleaning products get federal approval before hitting the shelves.
Hrubec and colleagues found that male and female mice exposed to two types of common quats—alkyl dimethyl benzyl ammonium chloride (ADBAC) and didecyl dimethyl ammonium chloride (DDAC)—had pups with much higher rates of birth defects than unexposed mice.
The defects “persisted for two generations after cessation of exposure," the authors wrote.
That was a little startling, just normal use of cleaner is sufficient to cause the birth defects. —Terry Hrubec, Virginia TechPerhaps most surprising was that the mice didn't even need to be directly dosed—just using quat-containing disinfectants in the rooms led to increased birth defect rates. Before researchers used the disinfectants in the rooms, about 1 out of every 1,000 embryos had a neural tube defect. After the chemicals were used in the rooms, the birth defect shot up to 15 percent after the chemicals were used in the rooms.
“That was a little startling, just normal use of cleaner is sufficient to cause the birth defects," Hrubec said.
Pat Hunt, senior author of the study and a researcher at Washington State University, said it's likely the mice in the room were exposed both through their skin and through inhalation. “In our original studies, we found that [quats] persist in the environment because it took months for levels to drop after the use of these disinfectants was discontinued in the facility," she said.
Also just exposing the males, and not the females, was enough to cause birth defects in the pups. “Normally we think of maternal environmental exposures and offspring, but we saw effects when only exposing fathers," Hrubec said.
The defects were neural tube defects, which are defects of the brain or spinal cord, Hrubec said. The two most common neural tube defects are spina bifida and anencephaly, which annually affect about 1,460 and 859 babies respectively in the United States.
About 150,000 to 200,000 babies born in the United States every year have a physical birth defect. There are many suspected culprits, Hrubec said, including genetic causes, use of therapeutic drugs and environmental chemicals. Folic acid, mandated a decade ago as an additive in domestic grain products, helps prevent neural tube defects.
While it's not clear if quats could have the same impacts on human babies, the sheer amount of the chemicals and our likely consistent exposure are a concern. More than 1 million pounds of quats are made every year in the U.S., Hrubec and colleagues wrote, with no health studies assessing human exposure.
“We don't know how much of quats are stored in us, or in which tissues they're stored," Hrubec said.
Hunt said one obvious concern is people who work in places with heavy disinfectant use, such as hospitals.
Cleaning product manufacturers stand by their products' safety. Prior to bringing products to market, The Clorox Company, which makes a suite of cleaning products some of which contain quats, “rigorously tests the product's safety and quality to ensure that it meets local, state and federal regulations," said spokesperson Rita Gorenberg in an emailed response to Hrubec's study.
She said Clorox didn't have time to fully evaluate the study but that product safety is a top priority for Clorox.
Quats have long been thought of as safe and, therefore, have been little studied. That may change.
This study comes three years after Hrubec and other researchers found that mice exposed to quats took longer to get pregnant, had fewer pups and suffered more miscarriages than non-exposed mice.
And just last year Hrubec's lab reported that mice exposed to quats had decreased fertility, with males' sperm decreased and females having fewer ovulations and getting pregnant less frequently.
Hrubec said the next research step is the figure is to examine quats and human. “We really need to find out more on what happens to quats once they get into our body," she said.