Applying sunscreen and insect repellent together could lower protection from the sun’s harmful ultraviolet radiation, scientists warned in a new study.
Researchers from CNRS in France assessed the combined use of sunscreen and one of the country’s top-selling insect repellents.
The findings, published in the journal Parasites & Vectors, reveals that mixing the two products can lead to a reduction in UV protection after application.
As disease-spreading insects like tiger mosquitoes are spreading across many countries, it has become an increasingly common habit to apply sunscreen and repellents together during outdoor activities.
The combination has particularly become crucial for travellers and other people who engage in outdoor activities and are exposed to mosquito stings and solar radiation.
In the latest research scientists tested how mixing sunscreen and insect repellent worked in protecting against UV radiation.
They applied the combination on skin biopsies and subjected them to artificial and natural UV rays emitted by the Sun to faithfully reproduce the real conditions.
“To our knowledge, our study is the first to evaluate the potential toxicity of combining real-life sunscreen and insect repellent products using ex vivo human skin samples,” scientists wrote.
Using a new AI system, researchers then analysed thin sections of the biopsy, corresponding to the different layers of actual skin.
The AI tool enabled scientists to measure the stress response of skin cells to radiation.
The application of just the commercial sunscreen was found to provide “efficient protection” against UV radiation on the skin model.
On the other hand, the mosquito repellent as a single product did not exert any protective or toxic effect.
However, researchers found a decrease in UV protection when a mixture of sunscreen and insect repellent was used.
“Notably, we found that concurrent application of the insect repellent with the sunscreen significantly decreased the UVB protective effect of the sunscreen,” researchers wrote.
Scientists hope the findings could help inform better application protocols for the two protective creams.
“The described methodology has the potential to inform health policy guidelines and end users on how to chose effective and safe insect repellents and sunscreens,” they wrote.
The research also offers insights into the use of AI along with techniques like digital morphometry to assess tissue layers and determine the extent of skin injury.
Scientists hope their research methodology can be used in future studies to gather information on the toxicological profile of other topically applied formulations.
They believe it may also be useful for diagnostic purposes such as in evaluating skin’s response to harmful substances like pesticides, air pollutants and water contaminants.