Dr Gabe Mirkin citing new research has shown that excessive handwashing can strip the skin of oils that prevent infections and also leave the tissue more vulnerable to ultraviolet rays that cause melanomas. He also reports that staph epi bacteria produce a chemical that when injected into mice caused a dramatic decrease in melanoma. Killing this bacteria with excessive washing may therefore lead to an increase in melanoma. Furthermore antibacterial soaps that contain triclosan can contribute to resistant bacteria. His conclusion is that some hygiene is good but that too much may be harmful.