Kose establishes method for assessing the impact of sunscreen on coral growth

 Kose, in collaboration with Okinawan coral farming expert Koji Kaneshiro, has established an evaluation method that can confirm the effect of actual sunscreen use on coral growth. By this method, we evaluated the sunscreen types (gel, milk) that are widely used by the company, both with and without UV absorbers, and confirmed that none of them adversely affected coral growth.

Some UV protection components contained in sunscreen have been reported to have an adverse effect on coral growth, and sales, carry-on, and use are prohibited in areas with coral reefs such as the state of Hawaii in the United States. Meanwhile, the Personal Care Products Council (PCPC) is concerned about the lack of scientific evidence and is cautious about refraining from using sunscreen, which is an effective way to protect people from UV rays. 

Based on this situation, the company expanded its efforts for coral conservation through the "SAVE the BLUE" project, which has been ongoing since 2009, to the research area, and in February 2022, ethylhexyl methoxycinnamate (octinoxate). It was confirmed that seven types of UV protection components, such as, do not affect coral growth at environmental concentrations.

This time, we established a method that can evaluate the effect of actual sunscreen use on coral, and confirmed that a general-purpose sunscreen agent type (gel, milk) has an effect on coral growth.

In the research, we used an experimental system for healthy coral breeding in the aquarium established by the company and Mr. Kaneshiro, and evaluated the impact on coral growth assuming the actual use of sunscreen. In order to bring it closer to the actual usage situation, a certain amount of sunscreen preparation was applied on the substrate and dried, and the test sample was used.

The amount applied was calculated from the average body surface area of ​​an adult and 2 mg per cm2, which is the recommended amount of sunscreen used. This is equivalent to the concentration of 10 adults with sunscreen applied to the whole body in one lane of a 25m pool, and the effect on coral should be evaluated assuming a situation where sunscreen users are densely packed. I thought it was possible enough.

As a coral sample, we used Usuedamidoriishi, which is one of the reef-building corals, and set this test sample in a water tank that generated an appropriate water flow, assuming actual seawater, and set it in it for 2 weeks. A breeding experiment was conducted. The health condition of the coral was judged by visual evaluation and image evaluation by experts.

In the constructed experimental system, four typical sunscreen preparations were used, and the effect of their use on coral growth was evaluated. There were two types, a gel type and a two-layer milk type, with and without UV absorbers, for a total of four types.

SPF and PA, which are indicators of the UV protection effect, are set in the range of SPF35 to 50+ and PA +++ to ++++ so that they can cover the specifications widely used by the company. The company selected four types of UV absorbers that are widely used by the company, and two types of UV scatterers, zinc oxide and titanium oxide.

A test sample was prepared for each of these sunscreen formulations, placed in an aquarium, and a two-week breeding experiment was conducted.

As a result of visual evaluation and image evaluation after 2 weeks, no abnormality was found in coral growth in any of the specimens. From the above, it was confirmed that these four types of sunscreens do not affect the growth of corals in actual use.