Popular leave-on cosmetics such as sunscreen and lip balms may pose a hidden microplastic risk, scientists warn

We often think of skincare as a pampering ritual, an opportunity to nourish our skin and express our individuality. But as recent research from the University of Birmingham reveals, some of the popular “leave-on” products we use daily — like sunscreens, moisturisers, and lip balms — might be doing more harm than good. Specifically, microplastics in these products are flying under the radar, raising serious concerns about both environmental and health implications.

While most regulatory frameworks have targeted rinse-off products — think face washes and shampoos—leave-on products have received scant attention. This oversight is alarming, especially considering that microplastics, which can be tiny plastic particles or fibres, are prevalent in many of our favorite skincare staples. Dr. Anna Kukkola, a researcher at the University of Birmingham, notes, “The contribution of ‘leave-on’ cosmetics to microplastic pollution is a critical, yet underexplored aspect of environmental contamination.”

In their critical review, the researchers analysed 2,381 products and found that only two were classified as leave-on. This glaring gap can be attributed to several factors: the challenges in extracting microplastics from complex formulations and the prevailing public perception that the microplastic issue has been adequately addressed due to bans on rinse-off products. But the truth is, leave-on products could be significant contributors to the microplastic problem.

Health risks of microplastics

The health implications of daily exposure to microplastics in leave-on products remain largely uncharted territory. With limited research on how these particles interact with our skin after application, the potential for absorption into our bodies — through mechanisms such as hair follicles and sweat ducts — raises red flags. Dr. Kukkola emphasises this point, stating, “Given how much of these formulas our bodies can and do absorb, it is concerning that little to no research has taken place to investigate the associated health effects.”
Another critical insight from the study is the misuse of the term “microbeads.” Typically associated with rinse-off products, this term has been inaccurately applied to all microplastics in cosmetics, resulting in regulatory blind spots. This mislabeling has skewed global legislation towards rinse-off products, leaving a significant portion of the microplastic contamination from leave-on products unregulated.

Call for action and future research

The researchers are not just pointing out problems; they are advocating for solutions. Collaborative efforts are underway to develop new methods for extracting and analysing microplastics in leave-on cosmetics. This initiative, spearheaded by Dr. Sophie Comer-Warner from the University of Illinois Urbana-Champaign and Professor Iseult Lynch, aims to fill the critical knowledge gaps identified in the study.
Professor Lynch warns, “While the microplastics themselves might be relatively benign, a number of other chemicals are intrinsically bound into or onto the microplastics in complex leave-on formulations, including potentially PFAS, plasticisers, and other chemicals known to be either carcinogens or endocrine disruptors.”

As we lather on our moisturisers and slather on sunscreen, it’s crucial to be aware of what we’re putting on our skin. The beauty industry is evolving, and with it, our understanding of safety and environmental impact must grow. It’s time to advocate for better regulations and more research on the unseen dangers of our beloved leave-on skincare products. By staying informed and demanding transparency from manufacturers, we can ensure that our beauty routines don’t come at the expense of our health or the environment.

The findings of this research have been published in the Journal of Hazardous Materials and can be accessed here.