Common ingredients in the cleaning sprays for your kitchen and bathroom make mice less fertile, suggesting the compounds could do the same to humans, according to a new study.
Health researchers are concerned about specific chemicals used in cleaners—including popular brands like Lysol, Clorox and Simple Green—called quaternary ammonium compounds, used to kill microorganisms. Recent laboratory work from Virginia Tech University scientists found that when mice are exposed, both males and females have some unsettling impacts, such as weaker sperm and decreased ovulation.
Industry representatives have pushed back on the research, saying federal agencies deem the chemicals safe and that mice were exposed to unrealistically high levels.
The study, published today in Reproductive Toxicology, comes as U.S. infertility rates appear to be rising. A growing body of evidence suggests that environmental chemicals are playing a role.
“When we see effects in mice we should be concerned about effects in humans,” said Tracey Woodruff, a professor at the University of California, San Francisco, who specializes in reproductive health and the environment.
Even if you don’t clean, you might be at risk of exposure. Quaternary ammonium compounds are also used in algae-killing swimming pool chemicals, lumber treatments, anti-static laundry products and some cosmetics.
In the study, researchers exposed male and female mice to two common types of the compounds—alkyl dimethyl benzyl ammonium chloride and didecyl dimethyl ammonium chloride—through their water. Exposed female mice had reduced ovulation and spent less time in “heat”, when they’re most fertile.
Exposed male mice had less concentrated sperm. Also their sperm was less effective at moving through female mice to fertilize eggs.
Terry Hrubec, senior author of the study and associate professor of anatomy and embryology at Virginia Tech University, last year reported that mice exposed to these compounds took longer to get pregnant, had fewer pregnancies and gave birth to smaller litters. The current study aimed to tease out gender-specific problems identified in that earlier research.
The compounds are very effective at keeping houses, hospitals, restaurants and other industries free of microbes and other contamination and are widely used.
There aren’t any human studies monitoring exposure, but the chemicals’ ubiquity has “likely resulted in widespread human exposure,” Hrubec and colleagues wrote in the current study.
“You’re going to get populations with higher exposures … men and women working in janitorial services, or for cleaning companies,” Woodruff said.
Paul DeLeo, associate vice president, environmental safety at the American Cleaning Institute, which represents cleaning product manufacturers, said the study raises “unjust concerns.”
He pointed out that both the U.S. Environmental Protection Agency and the Food and Drug Administration have tested the chemicals and deemed them safe.
“The researchers also overdosed the mice tested in their study with levels of the ingredient at a rate hundreds of times greater than what would be consider a safe use level (based on EPA standards),” DeLeo said in an email.
A task force representing the Consumer Specialty Product Association echoed DeLeo's criticism, adding that the study’s conclusions “ignore 'real world' experience and scientific scrutiny over more than 30 years,” in an email.
Some of the mice were dosed at very high levels, Hrubec acknowledged. But male mice given low doses still had reproductive problems, she said.
In addition, some male mice weren’t dosed at all but rather lived in a cage and room where the compounds were used to clean cages and floors and still had impacted sperm, she said.
Proper functioning hormones are vital for reproduction, and much research recently has focused on endocrine disrupting chemicals, which mimic and alter hormones.
It is too early to speculate why these cleaning chemicals are causing problems for the mice, Hrubec said.
But some of the impacts—such as the reduction in number of “heat” cycles for the females—are “hormonally driven,” raising suspicion of endocrine disruption, she said.
There are many potential causes for infertility, and tracing population trends can be problematic. However, as Hrubec notes in the study, from 2001 to 2010 the artificial insemination rate in the U.S. increased 37 percent.
Meanwhile sperm counts across the world have significantly decreased over the past 70 years.
Dr. Jeanne Conry, an obstetrician and past president of the American Congress of Obstetricians and Gynecologists, said most physicians do not understand how little research is done on chemicals prior to being released into the environment. These studies, she said, should be taken into account.
“We walk a fine line between being alarming and being aware,” Conry said. “I tell women eat healthy, live a healthy lifestyle and keep your cleaning as simple as possible, maybe use something like vinegar and water.”