Scientists find link between household chemicals and birth defects in mice

Chemicals found in everyday personal and household products such as eye drops, cleaners, detergent, fabric softener, shampoo and conditioner, have been linked to neural tube birth defects in both mice and rats.

Researchers at Virginia Tech have found a connection between common household chemicals and birth defects. Known as quaternary ammonium compounds or 'quats', the chemicals are frequently used as disinfectants and preservatives in household and personal products such as cleaners, laundry detergent, fabric softener, shampoo and conditioner, and eye drops. The research demonstrated a link between quats and neural tube birth defects in rodents. Dr Terry Hrubec, associate professor of anatomy at the university's veterinary college, says that most people are exposed to such chemicals on a regular basis:

"These chemicals are regularly used in the home, hospital, public spaces, and swimming pools. Birth defects were seen when both males and females were exposed, as well as when only one parent was exposed. The fact that birth defects could be seen when only the father was exposed means that we need to expand our scope of prenatal care to include the father."

Dr Hrubec and her colleagues investigated the effect of two commonly used quats - alkyl dimethyl benzyl ammonium chloride and didecyl dimethyl ammonium chloride - often listed on ingredient lists as ADBAC and DDAC. The team found that exposure to these chemicals resulted in neural tube birth defects, the same birth defect as spina bifida and anencephaly in humans. Worryingly, Hrubec found that mice and rats did not even need to be dosed with the chemicals to see the effect. Her research shows that simply using quat-based cleaners in the same room as the mice was enough to cause birth defects:

"We also observed increased birth defects in rodents for two generations after stopping exposure."

An earlier study in Hrubec's laboratory found that these chemicals led to reproductive declines in mice. Follow-up research found that quats were decreasing sperm counts in males and ovulation in females. The research raises the possibility of quats contributing to human infertility, which has been on the rise in recent decades:

"We are asked all of the time, 'You see your results in mice. How do you know that it's toxic in humans? Our research on mice and rats shows that these chemicals affect the embryonic development of these animals. Since rodent research is the gold standard in the biomedical sciences, this raises a big red flag that these chemicals may be toxic to humans as well."

Quaternary ammonium compounds were introduced in the 1950s and 1960s before the standardisation of toxicity studies. Chemical manufacturers conducted some toxicity studies on the compounds during this period, but they were never published. Hrubec noted that an epidemiological study could determine whether people who have a high rate of exposure, such as healthcare workers or restaurant servers, have a more difficult time becoming pregnant or have a greater likelihood of having children with neural tube birth defects, but no such study has been conducted to date.