Hand hygiene, dermatitis: nature trumps nurture

Washing more than 10 times daily ups risk

Frequent hand washing appears to heighten the risk for irritant contact dermatitis in health care workers, particularly those genetically predisposed to the condition, investigators report. New research examining the risk factors for irritant contact dermatitis — a common skin condition marked by scaling, redness, itching, and burning due to a chemical substance on the skin — found that health care workers who washed their hands more than 10 times per day were more likely to develop the condition than those who washed their hands less frequently.

The study found that certain people appear to be genetically predisposed to skin reactions to irritant detergents, with those who do "wet" work in low-humidity conditions particularly vulnerable to hand dermatitis, says Susan Nedorost, MD, lead investigator and associate professor of dermatology at University Hospitals Case Medical Center in Cleveland. "The primary objective of our study was to determine whether certain people are more prone to irritant contact dermatitis than others," she tells Hospital Infection Control. "We showed that this is the case. Workers who had an irritant response to an experimental patch test with low concentration detergent were more likely than those without such a reaction to experience hand dermatitis."

Conducted in collaboration with the National Institute of Occupational Safety and Health (NIOSH), the study was recently presented by Nedorost in San Antonio at the 66th Annual Meeting of the American Academy of Dermatology. The study included a total of 100 health care workers who washed their hands at least eight times daily. Study participants were asked to complete a questionnaire to identify frequency of hand washing, use of alcohol-based cleansers, history of specific medical conditions (including asthma, eczema, and psoriasis, among others), and family history of dermatitis or eczema. Patch tests to determine how easily the skin was irritated by detergents also were conducted on the study participants. Low concentrations of three common detergents were patch tested to predict which patients were at risk for hand dermatitis.

NIOSH studies genetic link

Data from the questionnaires and patch tests that were analyzed from 60 subjects who completed the study to date found that 63% of participants developed hand dermatitis. Specifically, 22% of participants who washed their hands more than 10 times per day developed hand dermatitis compared to only 13% of those who washed their hands fewer than 10 times daily. The reaction to low-concentration (2.5%) sodium lauryl sulfate (SLS) was a statistically significant predictor of hand dermatitis, whereas other common variables such as history of childhood eczema, glove use, and use of alcohol-based cleansers, were not significant, she notes. Specifically, the large percentage of participants who reacted positively to SLS and developed hand dermatitis far outweighed the number of participants who did not react positively to SLS, but subsequently developed hand dermatitis.

"This means that 'nature' is a more important factor for development of hand dermatitis than 'nurture' — what you do with your hands," she says. "The result is promising as NIOSH now will proceed with the second part of the study to look for genetic polymorphisms that predispose to susceptibility to irritant hand dermatitis."

That arm of the study will investigate the possible associations of genetic variations with susceptibility to hand dermatitis. For example, genetic variants in the gene-encoding filaggrin — a protein that binds to cells in the outermost layer of skin — have been shown to be strong predisposing factors for atopic eczema. "Variations in the filaggrin gene may cause a disturbance of the top layer of the skin, which serves as a barrier against environmental exposures such as frequent wetting and drying of the skin," she says. "Once the top layer of the skin cracks due to frequent wet/dry cycles, especially in conditions of low humidity where drying occurs rapidly, it results in inflammation. This is how irritant hand dermatitis begins."

In comments she emphasizes go beyond the scope of the study, Nedorost told HIC that alcohol rubs are likely to cause less irritation than washing with soap in low-humidity conditions (i.e., winter in the Midwest). "We clearly showed that hand dermatitis was more common and more severe in our health care workers between November and April in this study than during the May-October interval," she says. "I don't know if alcohol-based cleansers or [soap] washing is better during the summer. Certainly, alcohol-based cleaners should not substitute for washing if hands are grossly soiled. Our hospital also prohibits their use when caring for patients with C. difficile because alcohol may not kill the spores."

Still, when appropriate, alcohol-based hand cleansers should be substituted for soap hand washing, she recommends. In addition, a cream or ointment-based emollient should be applied immediately after water exposure before the skin is completely dry. The goal is to prevent rapid drying and cracking, so applying the emollient after the skin is dry is not nearly as beneficial, she says.