The sun's rays can harm anyone's skin or eyes, but sun protection is especially critical for people who have skin cancer or are undergoing radiation or chemotherapy.

For cancer patients, sun-protective clothing may help prevent illness or even death.

Consumers need assurance that clothing being marketed as sun protective does indeed protect against harmful ultraviolet radiation.

A University of Nebraska textile scientist's research on ultraviolet protective fabrics is helping clothing manufacturers and consumers make better-informed decisions about sun-protective clothing and helped lay groundwork for establishing national standards.

Patricia Crews' work yielded some surprising results. While studying whether ultraviolet absorbers remain effective after laundering, Crews found that washing actually enhances sun protection in cotton fabrics because most commercial detergents contain optical brightening agents that absorb or deflect UV rays.

Crews also helped develop a simple method for measuring UV transmission through fabrics and for calculating a textile's Ultraviolet Protection Factor (UPF) factor, which is similar to sunscreen's sun protection factor.

"Most manufacturers must have this testing performed for them by a textile testing service such as ours at UNL," the Institute of Agriculture and Natural Resources scientist said.

Crews' research helped her become a leader in establishing U.S. standards for sun-protective clothing, which were finalized in 2000. She chaired the American Association of Textile Chemists and Colorists committee and was secretary of the American Society for Testing and Materials (ASTM) committee.

These committees created standards for how textiles should be prepared for UV transmission testing. They developed a standard prescribing how UV-protective clothing should be labeled with a UPF number, which ranges from 15 to 50+. The higher the UPF, the longer a person can stay in the sun before skin under the fabric becomes red.

The Federal Trade Commission and the Consumer Products Safety Commission worked together with ASTM members to develop the standards, Crews said. These agencies strive to assure that all textile products claiming to be UV-protective are prepared, tested and labeled according to standards Crews helped develop.

Standards are voluntary but the clothing industry is being urged to quickly adopt them for its own legal protection and, ultimately, for consumers' health and safety.

"The government would prefer that the clothing industry self-govern and self-regulate itself," said Crews, a College of Human Resources and Family Sciences scientist.

Questions to the Consumer Product Safety Commission about the effectiveness of sun-protective clothing helped spur the standards' creation.

A minimal amount of sun exposure may be healthy, but prolonged exposure to ultraviolet radiation increases the risk of reddening skin, wrinkles, premature aging and skin cancer. More than 1.3 million new cases of skin cancer are diagnosed annually in the United States, Crews said.

A niche market has developed for sun-protective clothing that better protects against UV rays than most conventional clothing.

"The problem is that sun-protective clothing manufacturers face a confusing array of published research that contains many contradictory claims," Crews said. Her research allayed some fears. Because it showed laundering increases the UPF, Crews said, "it assured the clothing industry that the rating the clothing or textile was given when it was new was going to remain the same."

She wants to more clearly define the influence of fiber type and fabric porosity, thickness and thread count on the UV-blocking properties of undyed fabrics. Her findings thus far indicate fabric porosity is the single best predictor of UV-blocking capacity. Fiber type and thickness also are important.

Polyester, silk and wool fabrics are better UV blockers than cotton or rayon when porosity and thickness are factored in, she said.

Her research has a personal dimension. Crews had skin cancer and one of her closest high school friends died of malignant melanoma, the rarest, but most deadly, skin cancer.

"Those things really sparked an even greater interest and commitment than I might otherwise have had," Crews said.

The USDA helped fund this research.

– Linda Ulrich

IANR Textile Scientist Patricia Crews measures the Ultraviolet Protection Factor of a knitted fabric being considered for sun-protective clothing. She is using a UV-visible spectrophotometer with special software for calculating UPF, a value for rating the protective qualities of fabrics. UPF is similar to SPF values for sunscreens.