Reality check: What can we expect from an ecological risk assessment of UV filters on coral reefs?

In 2018, Hawai'i banned the sale and distribution of sunscreens containing the ultraviolet (UV) filters oxybenzone and octinoxate based on laboratory studies that indicated that they have adverse impacts on coral reefs (Downs et al., 2014). While this was not the first ban on sunscreen UV filters, it was the most widely reported and controversial in the United States. Proponents of the ban highlighted the importance of coral reefs and the multitude of stressors contributing to their rapid global declines. Those who opposed it expressed concerns that it may reduce sunscreen options and lead to increasing incidents of skin cancers; this was succinctly summarized as “Essentially, … two ingredients that are both safe [for humans] and effective for use in sunscreen are being banned … on the basis of a single study…” (Hawai'i bans sunscreens that harm coral reefs, CNN July 3, 2018). While most can agree that the effectiveness of a chemical should not negate risks to the environment (Carson, 1962), it is important to realize that chemicals are often regulated on the basis of a single study—or no studies at all. For example, new chemicals registered under the Toxic Substance Control Act (TSCA) may be regulated based solely on chemical structure. However, such reactions highlight that most stakeholders do not have a good understanding of how environmental risks are evaluated and will be disappointed in the data available to inform such decisions for UV filters.

In 2020, US Congress passed an omnibus appropriations bill requiring the USEPA to partner with the National Academy of Sciences (NAS) to conduct a review of potential impacts of currently marketed UV filters on the environment. The mandate was to summarize the scientific literature, identify additional research needed to conduct an ecological risk assessment (ERA), and identify potential public health implications of reduced sunscreen use. The NAS found that UV filters are detected in water samples from around the world in concentrations that cause effects to organisms in laboratory tests and are found in the tissues of organisms ranging from crayfish to dolphins. The NAS recommended that the USEPA should conduct an ERA for all currently marketed UV filters and any new ones that become available (National Academies of Sciences [NAS], 2022). Ecological risk assessments evaluate the likelihood that the environment might be adversely impacted by a chemical and are often conducted in a tiered process that begins with a more protective screening-level assessment and moves to more realistic assessments, as needed, to reduce uncertainties. Ecological risk assessments are comprised of exposure and effects analyses that are integrated into a risk characterization. Each of these analyses contains their own uncertainty that provide fodder for criticism, even though the uncertainties typically stem from lack of or limited data that are beyond the control of the risk assessor. First, I review the uncertainties associated with the primary phases of the ERA as relevant to UV filters in marine environments to provide a reality check of what we can expect from such efforts. From there, I provide a recommendation for the next steps that will require a global network of collaboration to provide useful and impactful assessment to reduce the environmental impacts of UV filters.

Sandy Raimondo: Writing—original draft; writing—review editing.

The views expressed in this article are those of the authors and do not necessarily represent the views or policies of the USEPA.