Significant gaps in the regulation and safety testing of lip cosmetic products have been identified in two international critical reviews published on Aug. 4, leaving consumers potentially exposed to unassessed risks.
The studies, commissioned by the Lip Service Alliance in partnership with University of Birmingham researchers, highlight issues such as reliance on inappropriate skin models and outdated data on usage and ingestion rates. Lip cosmetics—including lipsticks, glosses, balms, oils, masks and stains—are classified as topical cosmetics intended for external use only. However, these products are routinely ingested or absorbed through the lips' tissue.
Researchers examined regulations across the UK, US, European Union, Canada, China and South Korea. They found that most countries' frameworks do not account for absorption through lip tissue. In stricter regions like the UK and EU, absorption data is based on regular skin models with an intact barrier layer that differs biologically from lip skin. The reviews note that "the lips should not simply be treated as ordinary skin," citing their similarity to oral mucosa, which is more permeable than regular skin.
Professor Iseult Lynch of the University of Birmingham said, "These critical reviews are an important first step in addressing a significant evidence gap in our understanding of how substances in lip products interact with the body... Our findings suggest that the lips should not simply be treated as ordinary skin. They share important characteristics with the mucosal tissues inside the mouth... This indicates a clear case for developing more lip-specific exposure assessment methods based on the best available science."
The research points out that current regulations often rely on decades-old studies to estimate ingestion rates and exposure assumptions—figures which may no longer reflect modern product types or usage patterns. Contemporary studies show some users may ingest much higher amounts than previously assumed due to new product formats and increased application frequency encouraged by social media trends.
Laura DiGirolamo of The Lip Service Alliance said, "Lip products are often made to taste like food and desserts yet formulated with plastics... There are so many ingredients restricted in food yet unrestricted in lip products we know are being ingested... Nobody has been required to look at what years of that does, and an absence of proven harm is not the same as safety." She added, "If you identify a problem without a solution or a pathway forward you cannot inspire change... We had to illustrate how real this issue is with robust peer-reviewed research."
The Lip Service Alliance calls for updated testing methods reflecting actual use patterns and biological differences in lip tissue. The group invites further engagement from industry stakeholders to close regulatory gaps.
