A new study warns that chemicals commonly found in cleaning products quartenary ammonium compounds (QACs) can reduce fertility. But there are some problems extrapolating those results out to humans.
The study was in mice, which is not a bad thing, almost every study has had a mouse model at some point, but these mice were exposed the chemicals in their food or water. It's safe to assume that the great majority of people don't drink cleaning compounds. And the route of exposure to a chemical can make a big difference in any effects it may have. We eat butter just fine but we can't inhale it.
Anything consumed by mouth (food, water, medicines) gets absorbed into the blood from the intestinal tract and passes directly to the liver. Depending on what it is, the liver may substantially alter it chemically, sometimes in such a way that it is directly excreted by the kidneys in the urine. Whatever doesn't pass into the blood can leave the body in the feces. Volatile chemicals that are inhaled can pass into the blood directly from the lungs, from which they are distributed to all parts of the body without being altered. So trying to extrapolate toxicity of a compound for humans based on animal exposure to food or drink is fraught with problems, as we have explained in many publications for example, here.
The investigators in the present study point to the increase in assisted reproductive procedures (such as in vitro fertilization) between 2001 and 2010 as a reason to suspect environmental damage. However, this increase may well be due to other factors, such as women delaying reproduction until older ages, improvements in the technologies, as well as more insurance coverage of such procedures. As the authors themselves point out, the QACs have been in use for over 50 years so wouldn't one have expected any reproductive effects to have occurred well before 2001?
Thus, the finding that female and male mice suffered some reproductive abnormalities after long-term exposure to QACs really is of little import when it comes to human abnormalities even for people who clean their bathrooms daily.