Another reason to avoid products with Triclosan. From Science Daily:
An antimicrobial agent found in common household soaps, shampoos and toothpastes may be finding its way inside human noses where it promotes the colonization of Staphylococcus aureus bacteria and could predispose some people to infection.
Triclosan, a human-made compound used in a range of antibacterial personal care products such as soaps, toothpastes, kitchen surfaces, clothes and medical equipment, was found in nasal passages of 41% of adults sampled. A higher proportion of subjects with triclosan also had S. aureus colonization. S. aureus could promote infection in some populations such as people undergoing surgery.
Triclosan has been around for the past 40 years, says senior study author Blaise Boles, PhD, an assistant professor of molecular, cellular and developmental biology at the university, and has been incorporated into many antibacterial household products within the past decade. Other studies have found traces of triclosan in human fluids including serum, urine and milk, and studies in mammals have found that high concentrations of triclosan can disrupt the endocrine system and decrease heart and skeletal muscle function.
"It's really common in hand soaps, toothpastes and mouthwashes but there's no evidence it does a better job than regular soap," Boles says. "This agent may have unintended consequences in our bodies. It could promote S. aureus nasal colonization, putting some people at increased risk for infection."
Additional experiments found that S. aureus grown in the presence of triclosan was better able to attach to human proteins, and that rats exposed to triclosan were more susceptible to S. aureus nasal colonization.