20 SUN CARE
legislation has passed similar bans focused on oxybenzone and octinoxate in Hawaii, Key West, Aruba, Bonaire, the U.S. Virgin Islands and the Marshall Islands, which will take effect in 2021. With the recent announcement from the U.S. Food and Drug Administration declaring that the only two Generally Recognized as Safe and Effective (GRASE) UV filters are zinc oxide and titanium dioxide, Hawaii has since proposed new legislation that is still in committee, which would allow only sunscreen products with ingredients deemed GRASE by the US FDA to be sold or distributed in Hawaii. As regulations continue to restrict the
use of sunscreen ingredients, it is important for consumers to be able to understand the true impact their choices in sunscreen have on the environment. With no concrete definitions as to the labeling claims of “reef-safe” or “reef friendly,” consumers are taking their cues from large marketing campaigns and social media influencers. According to
oberlo.com, an estimated 54% of social browsers use social media to research their products and thus influence their buying decisions. Through the Positive Reef Initiative,
EverCare is dedicated to understanding our products and their impact on the environment for consumers to be able to make smart purchases when choosing their sunscreens. We are committed to offering ingredients and UV filters that will allow for the creation of safe products. In our view, this starts by understanding the true impact of our ingredients on coral reefs and presenting a balanced view to empower consumers to make informed
PERSONAL CARE NORTH AMERICA
choices. The key to achieving this balanced view is to move from a hazard profile to a risk and exposure scenario to look at the actual impact different products have on the environment. As zinc oxide has been considered to be one of the more reef-safe UV filters, we dive into its assessment here.
Assessing zinc oxide in coral reef environments Zinc is an essential element that is needed for the optimal growth and development of all living organisms. Due to its general natural availability and unique characteristics, zinc is an essential component of many metabolic processes that sustain life for all organisms. Nevertheless, Zn and zinc compounds are labeled as ecotoxic for the aquatic environment for transportation.3
This
labeling is based on the intrinsic hazard profile for bulk materials and is mainly driven by the release and toxicity of Zn2+. The observed toxicity is determined by concentration and exposure time. It is true that some studies have shown that high Zn2+ concentrations and long exposure times can kill coral algae, but most of these studies have been done in an isolated test system at unrealistic high concentrations that are not relevant to actual real-life situations. Determination of reliable
concentrations of ZnO in surface waters as a result of its use as a UV filter is key in a risk and exposure assessment. This is not an easy task due to low concentrations in the environment. A comprehensive evaluation was recently performed by
EverCare on measured and estimated concentrations of Zn in both fresh and marine waters, including those of touristic shore areas. This has demonstrated that the observed ZnO levels remain well below the predicted no-effect concentration of zinc oxide and as such has no observed adverse or toxic effect.4,5 Consequently, due to the use of ZnO as UV filter in sunscreens, Zn2+ concentrations do not reach levels that provide toxicity or do harm to corals. In addition, not being considered in
most environmental toxicity studies is the subsequent persistence of a compound in the environment once exposed. Traditionally reported as biodegradability, the process by which organic substances are broken down by living organisms, this concept does not apply to minerals such as metals and metal oxides. Instead, an equivalent concept of rapid degradability can be applied for inorganic compounds. The degradability properties of minerals is assessed through a water column test, which is comprised of a sediment layer with a well-mixed water column on top. Minerals are added to the water column and the rate of removal is monitored. Studies have demonstrated that dissolved Zn2+ ions are rapidly complexed by ligands in the soil and surface waters, rendering them bio-unavailable, further reducing the assumed toxicity.6
Similar
water column experiments with zinc oxide have also shown it be “rapidly removed” due to immediate bonding to suspended particulate matter rendering it bio- unavailable, further validating the environmental safety profile of ZnO.
October 2020
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