Toxic effects of UV filters from sunscreens on coral reefs revisited: regulatory aspects for “reef safe” products

Abstract

Background Tropical coral reefs have been recognized for their significant ecological and economical value. However, increasing anthropogenic disturbances have led to progressively declining coral reef ecosystems on a global scale. More recently, several studies implicated UV filters used in sunscreen products to negatively affect corals and possibly contribute to regional trends in coral decline. Following a public debate, bans were implemented on several organic UV filters and sunscreen products in different locations including Hawaii, the U.S. Virgin Islands and Palau. This included banning the widely used oxybenzone and octinoxate, while promoting the use of inorganic filters such as zinc oxide even although their toxicity towards aquatic organisms had been documented previously. The bans of organic UV filters were based on preliminary scientific studies that showed several weaknesses as there is to this point no standardized testing scheme for scleractinian corals. Despite the lack of sound scientific proof, the latter controversial bans have already resulted in the emergence of a new sunscreen market for products claimed to be ‘reef safe’ (or similar). Thus, a market analysis of ‘reef safe’ sunscreen products was conducted to assess relevant environmental safety aspects of approved UV filters, especially for coral reefs. Further, a scientifically sound decision-making process in a regulatory context is proposed. Results Our market analysis revealed that about 80% of surveyed sunscreens contained inorganic UV filters and that there is a variety of unregulated claims being used in the marketing of ‘reef safe’ products with ‘reef friendly’ being the most frequently used term. Predominantly, four organic UV filters are used in ‘reef safe’ sunscreens in the absence of the banned filters oxybenzone and octinoxate. Analysis of safe threshold concentrations for marine water retrieved from existing REACH registration dossiers could currently also safeguard corals. Conclusion There is a substantial discrepancy of treatments of organic versus inorganic UV filters in politics as well as in the ‘reef safe’ sunscreen market, which to this point is not scientifically justified. Thus, a risk-based approach with equal consideration of organic and inorganic UV filters is recommended for future regulatory measures as well as a clear definition and regulation of the ‘reef safe’ terminology.

Criticisms in the Development of High-Protection and Broad-Spectrum “Natural/Organic” Certifiable Sunscreen

“…These data have raised alarms regarding toxicity towards humans and the environment [15], which have led some tropical places to ban four organic filters, thus, generating an alarm towards this type of substance [16]. An approach pursued in recent times is the search for new, natural, environmentally friendly molecules of an organic nature that can perform as sunscreen (UV) filters.…”

Towards the Development of Standardized Bioassays for Corals: Acute Toxicity of the UV Filter Benzophenone-3 to Scleractinian Coral Larvae

“…Quantitative comparisons with previous studies are difficult due to methodological and analytical inconsistencies, and due to the lack of analytical verification of exposure concentration in various previous studies as discussed in recent literature [ 49 , 50 , 51 , 52 ]. Up to this date, only two other studies performed toxicity assays with UV filters on coral larvae.…”

“…For example, Downs et al [ 36 ] reported mortality in coral larvae of Stylophora pistillata a LC 50 (i.e., concentration that kills 50% of the population) at nominal 139 µg L −1 after exposure to the organic UV filter benzophenone-3 (BP3 or oxybenzone). Based on these studies, policymakers in various locations (i.e., Hawaii, US Virgin Islands, Palau, Aruba and Bonaire) have already taken regulatory actions and banned the use of some organic UV filters including BP3, ethylhexyl methoxycinnamate (EHMC or octinoxate), octocrylene (OCR) and 4-methylbenzylidene camphor (4MBC) in sunscreens [ 49 , 50 , 51 ]. Those bans, however, are controversial as the underlying studies revealed several shortcomings (e.g., lack of analytical verification of exposure concentrations, inadequate controls, lack of environmental relevance) that question the reliability of some of the test results and the conclusions drawn within these studies [ 49 , 50 , 51 , 52 ].…”

“…Based on these studies, policymakers in various locations (i.e., Hawaii, US Virgin Islands, Palau, Aruba and Bonaire) have already taken regulatory actions and banned the use of some organic UV filters including BP3, ethylhexyl methoxycinnamate (EHMC or octinoxate), octocrylene (OCR) and 4-methylbenzylidene camphor (4MBC) in sunscreens [ 49 , 50 , 51 ]. Those bans, however, are controversial as the underlying studies revealed several shortcomings (e.g., lack of analytical verification of exposure concentrations, inadequate controls, lack of environmental relevance) that question the reliability of some of the test results and the conclusions drawn within these studies [ 49 , 50 , 51 , 52 ]. Several recent review articles have compiled a comprehensive overview about the current status of coral toxicity research on UV filters and their shortcomings [ 48 , 49 , 51 ].…”

“…Those bans, however, are controversial as the underlying studies revealed several shortcomings (e.g., lack of analytical verification of exposure concentrations, inadequate controls, lack of environmental relevance) that question the reliability of some of the test results and the conclusions drawn within these studies [ 49 , 50 , 51 , 52 ]. Several recent review articles have compiled a comprehensive overview about the current status of coral toxicity research on UV filters and their shortcomings [ 48 , 49 , 51 ]. Therefore, these results may be considered as preliminary and require further scientific evaluation, preferably conducted using standardized testing methods on corals including various relevant life stages [ 49 , 53 ].…”