"Because of the emerging use of biometrics in daily living, I think hand dermatitis is an upcoming problem," said lead author Dr. Lee Chew Kek, a dermatologist at UCSI University in Kuala Lumpur. "This can have effects on the economy, jobs and security."

Fingerprints are still the most common unique personal trait used to identify an individual. Other measurable unique biological features include the iris of the eye and even keyboard typing patterns. Analysts have projected that the global biometrics market will be worth $16 billion in four years.

Cracked or swollen skin can disrupt the unique crevice pattern found within individuals' thumbprints, which are increasingly used for security checks at banks or to access buildings.

According to an earlier study from Denmark, an estimated 15 percent of people worldwide will suffer from hand dermatitis - skin inflammation usually caused by an allergic reaction.

Lee told Reuters Health she provides hospital verification for patients who cannot have biometric data encoded into a computer chip on their Malaysian national identity card, called MyKad, because of unreadable fingerprints.

To the authors' knowledge, no previous study has investigated how often dermatitis patients fail fingerprint tests.

The research team recruited 100 patients with dermatitis affecting either thumb and 100 participants with healthy fingers as a comparison group. All participants possessed readable MyKad cards.

Each patient had three attempts with each thumb to get an accurate match with a fingerprint scanner that processed the images and linked them to MyKad data.

Twenty-seven of the 100 dermatitis patients failed fingerprint verification tests compared to only two participants in the comparison group.

Eighty-four in the patient group had areas on their thumbs where prints were missing or skin appeared mottled due to rough skin. The larger the area of so-called dystrophy, the more likely a patient was to fail the test.

Abnormal white lines in the prints caused by wrinkles or cuts were found in both groups. However, when white lines appeared in prints, dermatitis patients had a greater number of them. Researchers guessed that the cuts may ruin the pattern of tiny ridges within thumbprints.

Despite the limited size of the study, published in the Archives of Dermatology, the subject is important for dermatologists to be aware of, said Dr. Pieter-Jan Coenraads of the University of Groningen in the Netherlands.

"Human biology is a lot more variable than security authorities would like to believe, I think," said Coenraads, who was not involved with the study.

"Dermatitis is one of the many factors which can certainly affect fingerprint image quality," Steve Fischer, spokesman of the FBI's Criminal Justice Information Services division told Reuters Health in an email.

Disruptions in fingerprint images do happen in the FBI's Integrated Automated Fingerprint Identification System, which maintains more than 70 million print records, he said.

The FBI processes an average of 160,000 fingerprints each day with approximately three percent rejected due to poor image quality, Fischer wrote.

The division doesn't have a record of how many disruptions are attributable to dermatitis.

Since hand dermatitis is not a rare problem, "there may be a significant number of individuals who will be handicapped by fingerprint technology," explained Dr. Bruce Brod of the University of Pennsylvania, who was not involved with the study.

Though most hand dermatitis can be resolved with topical creams, people who have allergic contact dermatitis - like the majority of patients in this study - may struggle with constant exposure to irritants in the workplace, according to researchers.

Health care workers who constantly wash their hands, a mechanic who must finger greasy bolts and nuts inside an engine or a chef who slices lots of garlic and onions between the thumb and index finger may develop hand dermatitis, for example.

"In terms of treatment for hand dermatitis, we're still lagging behind. It tends to be a very chronic problem," Brod told Reuters Health.

SOURCE: bit.ly/WGwnAI Archives of Dermatology, online December 17, 2012.

• A Permanent Economic Emergency