Massage therapists should know the importance of a thorough hand washing, but according to the results of a new study, many Americans do not.

The Michigan State University study found that just 5 percent of people washed their hands in a manner sufficient to kill the germs that can cause infections, after using the restroom.

And 33 percent of people didn’t use soap, while 10 percent did not wash their hands at all. Males washed their hands less frequently, and less well, than females.

A university press release noted that, “Hand washing is the single most effective thing one can do to reduce the spread of infectious diseases, according to the Centers for Disease Control and Prevention. Failing to sufficiently wash one’s hands contributes to nearly 50 percent of all foodborne illness outbreaks.”

Vigorous hand washing for just 15 to 20 seconds with soap and water effectively kills germs, “yet the study found that people are only washing their hands, on average, for about 6 seconds,” the press release noted.

The study was based on observations of 3,749 people in public restrooms, and appears in the Journal of Environmental Health.