Fertility Problems Tied to Cleaning Agents

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ResearchBlogging.org

I know a fair number of zoos and aviculturists who disinfect the premises occupied by their breeding flocks of birds with quaternary ammonium compounds to prevent the spread of diseases, especially viral disease. But according to a story that just appeared in the top-tier journal, Nature, exposure to the quaternary ammonium compounds, ADBAC (n-alkyl dimethyl benzyl ammonium chloride) and DDAC (didecyl dimethyl ammonium chloride), could cause a sharp decrease in fertility. These two chemicals are widely used in hospitals, hotels and in avicultural and zoo facilities because they are present in the disinfectant Virex* (Image Supply). Obviously, when you are working with rare or endangered species in a captive breeding program, this is a very serious concern.

Quaternary ammonium compounds are derived from ammonium, but all four hydrogen atoms are replaced with "R" groups that are one of a variety of organic alkyl groups. The potency of these compounds depends upon the number and length of the R-groups and which atoms are contained within them. Quaternary ammonium compounds are strong bases because they carry a permanent positive charge, regardless of the pH of the solvent they are suspended in, so they are strong attracted to negatively-charged surfaces, such as skin, hair and cell membranes. They have a variety of uses, including disinfectants, surfacants, antistatic agents, fabric softeners and in drugs.

According to Patricia Hunt, a reproductive biologist at Washington State University in Pullman, Washington, these chemicals caused her research animals to experience fertility problems shortly after she had relocated her mouse colony to Pullman from Case Western Reserve Medical School in Cleveland, Ohio.

"After the move we began to experience breeding problems in our mouse colony. Only about 10% of females that were mated in one experiment got pregnant, and of those a large number of late-stage fetuses died," reports Dr. Hunt. "This is very unusual in mice."

Among those mice that did become pregnant, birth defects and other problems were also noticed.

"There were also discrepancies in the developmental ages. Some litters were accelerated, some litters were delayed," reports Dr. Hunt. "And we saw more birth defects in the first few months of our study than we had seen in our previous 13 years at Case."

Unfortunately, Dr. Hunt has not published her data because she has been unable to run the necessary controlled experiments to demonstrate that quaternary ammonium compounds are the definitive reason for the decline in reproductive performance.

"We did a side-by-side control," said Dr. Hunt. "We exposed ten cages and left ten cages, but we found after several months that we had reintroduced the contaminant into our clean cages through the washer. We tried hand-washing the cages outside the facility, but the variables were too hard to control."

Despite this lack of controlled experiments to support her preliminary findings, Dr. Hunt reported her suspicions earlier this month at the Society for the Study of Reproduction meeting in Kona, Hawaii, last month, she found that other scientists had similar experiences.

"I've had several people tell me they thought I'd spotted the answer to their problems," Dr. Hunt said, adding that "two mouse facility managers at Pullman told me they already knew it impacted on breeding performance, because they had seen it over the years and had removed the chemicals from their facilities."

These chemicals persist in the environment for long periods of time and according to Dr. Hunt, have deleterious effects on the ovary, uterus and in lactation.

"This group of compounds acts on the cell membrane, and does a fantastic job of killing everything. But, you know, we're composed of membranes too."

Even though birds are not mammals, they still have ovaries and produce eggs, and they, like all living things, have cell membranes so they also are vulnerable to the effects of quaternary ammonium compounds.

So what does Dr. Hunt use to disinfect her mouse cages now?

"We went back to the disinfectant that we had been using at Case," she said. "It's a chlorine-dioxide-based sanitizer called Clidox."

Clidox-S (PRL) has similar disinfectant propoerties to those of Virex. It kills bacterial spores, tuberculosis and other bacteria, fungi and even viruses.

Source

Maher, B. (2008). Lab disinfectant harms mouse fertility. Nature, 453(7198), 964-964. DOI: 10.1038/453964a

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That is pretty disconcerting. One wonders if this stuff has effects anything like as dramatic in other species? Given their failure to avoid contaminating their control cages, I find it hard to be too optimistic about the doses incurred by whatever lucky lab minion(s) get to clean the cages.

I imagine that there will likely be some followup work on this?