Consumer products groups have stepped up pressure on the US FDA to change course on its sunscreen ingredient approval process.
The latest push comes in joint comments from the Personal Care Products Council (PCPC) and Consumer Healthcare Products Association (CHPA) on the FDA's draft guidance on how industry should conduct maximal usage trial studies for topical active ingredients.
MUST studies are used to collect data on the potential risks a drug applied to the body may pose, when used at the maximum limits described on product packaging. And since 2016, they have been included as a method for demonstrating the safety and efficacy of sunscreen ingredients.
But a broad stakeholder group – including health NGOs, chemical and sunscreen manufacturers and dermatologists – has protested that the studies' methodologies have no "established protocol" for use on sunscreen ingredients.
And in the comments on the FDA's draft guidance, the PCPC and CHPA reiterated their recommendation that the agency include alternative approaches as part of its toxicological risk assessment and when determining acceptable margin of safety (MOS).
"We continue to strongly believe that valid and scientifically rigorous exposure assessments together with predictions of internal dose could be readily used as an alternative" to MUST studies, the groups wrote.
And they specifically mentioned approaches using in vitro/in silico data coupled with physiologically-based pharmacokinetic (PBPK) modelling. This would yield "a conservative estimate of internal dose that could be compared with equivalent data from animal studies to understand dosimetry, as part of the overall safety assessment," they said.
Pressure on existing ingredients
The comments are the latest in a decades-long challenge to get new ingredients to the market. The FDA has not approved a new active sunscreen ingredient since the 1990s, and has a backlog of eight substances – many of which are widely used elsewhere in the world – awaiting approval.
But recently these concerns have taken on greater importance, as pressure mounts against existing sunscreen ingredients.
Earlier this year, Hawaii passed a law to ban oxybenzone and octinoxate from sunscreen from 2021, citing concerns about their effect on coral reefs.
And in May, NGO Center for Biological Diversity petitioned the FDA to extend the prohibition nationwide.
Industry groups have argued that barring those two ingredients will result in the removal of 70% of products currently on the market, and that the science on the harm caused to the coral by the ingredients is inconclusive.
But both regulatory and consumer pressure on the substances continues to grow, with the Environmental Working Group (EWG) launching a campaign for oxybenzone to be phased out of sunscreens nationwide by 2020.
In its MUST guidance comments, the American Academy of Dermatology Association (AADA) cited the recent action on oxybenzone and octinoxate, when urging the FDA to "expedite collaboration" on approaches that will allow new sunscreen ingredients to get approval.
The medical association said it hopes to "facilitate discussion" between the FDA and industry so that the agency will "set forth study elements and considerations that industry is willing to perform".
"This long-lasting impasse is only to the detriment of the American public and must be addressed now," it added.