ANTI-POLLUTION
Reef-safe sunscreen: a formulator’s perspective
Shibu K, Anjali Gholap, Rachna Rastogi - Bregma Science ABSTRACT
The awareness about the harmful effects of UV rays on skin and the importance of sunscreen application in protecting our skin from these UV rays is growing. This is piloting the increasing demand for sunscreen products in the market. Along with the first-generation sunscreens, new organic UV filters and modified mineral sunscreen agents are available in the market claiming higher efficacy and no white cast on application. The impact of sunscreens on the environment, specifically marine life, is an unending debate. Evidence shows that some of the sunscreen ingredients may have a negative impact on the environment. In this review article we aim to dive deeper into the debate on the impact of sunscreen ingredients on coral reefs and the concept of ‘reef safe’ sunscreens. This aricle will assist formulators designing sunscreens with new claims and certifications.
Coral reefs are vibrant ecosystems that occupy less than 0.1% of the world’s ocean by area yet support a quarter of the marine life. However, they face significant threats.
Rising ocean temperatures and acidification cause coral bleaching, while pollution, coastal development, marine tourism and destructive fishing practices further damages reefs. Currently, approximately 60% of world’s coral reefs have been reported to be at risk.1 While the formation and breakdown of this marine eco-system is multifarious, key degradation occurs when the symbiotic relationship of corals with a group of algae, zooxanthalle is disturbed. The algae present on the coral surface not only give them a striking appearance, but they also provide the corals, food generated from photosynthesis. In turn, the coral polyps give the algae
a protected environment and necessary nutrients to carry out life processes. As this relationship is disturbed, the algae detach from the corals revealing a white color commonly termed ‘bleaching’. This damaged habitat then leads to widespread coral mortality and destructed ecosystems.2 Sunscreen ingredients have been reported
to have a noticeable effect on coral reef degradation. When we are looking into the
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statistics, Smithsonian Ocean 2022 data shows, roughly 14,000 tons of sunscreen entering into water ways across the globe every year from both sunscreen applications and wastewater runoff. In shallow areas that are popular with
swimmers, significant amounts of sunscreen can accumulate in the water. Researchers estimate that approximately 10% of the world’s coral reefs area are potentially threatened by sunscreen that washes off swimmers in reef waters. The study suggests that, as tourism continues to increase in tropical reef areas, the impact of sunscreens on coral bleaching could rise significantly in the future.3 Key materials in sunscreens are UV filters
that provide protection from UVA, UVB and blue light. Sunscreens can be formulated with organic, inorganic or a combination of UV filters. Organic UV filters such as octocrylene, oxybenzone and octinoxate have been reported to cause complete coral bleaching; these ingredients are able to induce the lytic cycle in symbiotic zooxanthellae with latent infections. Studies have demonstrated that even in
quantities as low as 10 µL/L the presence of these UV filters cause an expulsion of zooxanthalle in 18-48 hours. This process is aggravated under high temperature conditions
and may result in coral reef fatality.1 Similar detrimental effects have also
been reported with nano-sized inorganic sunscreens. Bioaccumulation of nano zinc oxide and titanium dioxide can induce severe growth inhibitory responses in zooxanthellae leading to destruction of coral reefs.4,5
Designing reef safe sunscreens Even though the evidence for coral reef bleaching due to sunscreen wash off in water bodies is compelling, it is not conclusive. Nonetheless, due to the presence of newer age UV filters, consumers can select products based on ingredients with less to no evidence of bioaccumulation. Table 1 lists the UV filters currently under
scrutiny for reef toxicity and materials expected to be safe.
Formulation challenges For inorganic sunscreens use of non-nano zinc oxide and titanium dioxide can give equal or more protection while being safe for the environment.6,7
Microsized TiO2 is
the most effective in UVB, while ZnO has high effectiveness in the UVA range; their combination helps achieve broad band UV protection.
October 2024 PERSONAL CARE
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