Plant lignin improves efficacy of sunscreen

In a new study, scientists point to the potential of lignin to bolster sunscreen performance.

Lignin is an organic polymer found in the cell walls of many plants. It offers structural integrity and rigidity and is found in high concentrations in wood and bark. It's also one of the paper industry's biggest waste products.

Most sunscreens use synthetic compounds to block ultraviolet rays, but producers have been looking for alternatives to meet the consumer demand for natural ingredients. Some have looked to sources such as green coffee, soy and papaya.

A team of researchers Canada and China teamed up to test the potential for lignin to bolster the burn-prevention abilities of sunscreen. They pitted five types of lignin against UV rays.

As detailed in the journal ACS Sustainable Chemistry & Engineering, organosolv lignin proved the most potent. When added at a concentration of just one percent, the lignin's presence doubled the sunscreen's sun protection factor, or SPF. A 10 percent addition amplified the sunscreen's SPF by six.

Though all the lignin polymers boost SPF in small amounts, when added in excess, some lignin types caused the sunscreen to begin separating.

"More work is needed, but the results represent a promising first step toward the development of lignin-containing sunscreen, say the researchers," the American Chemical Society wrote in a news release.