Sun filters: endocrine disruptors, corals, nanoparticles - a doctor's decipherment.
Sunscreens are the focus of two major controversies: they are suspected of acting as endocrine disruptors and of contributing to coral bleaching. Added to these accusations is the question of nanoparticles in mineral filters. Let's take a closer look, with scientific sources, at these now indispensable components of sun creams.
Are sunscreens endocrine disruptors ?
The most widely discussed filter is oxybenzone, but other molecules are also targeted: enzacamene, octinoxate, octocrylene and homosalate. Numerous in vitro and in vivo studies have been carried out, but it remains difficult to draw any clear-cut conclusions, as the quantities absorbed through the skin are small.
However, a study published in 2020 showed that certain filters - avobenzone, octocrylene, homosalate and oxybenzone - were indeed found in the participants' blood, but did not lead to the conclusion that they were dangerous. (Matta MK et al., JAMA, 2020).
Are they suspects?
Yes, several organic filters are among the molecules regularly studied for potential endocrine effects.
Are they really?
Given the current state of knowledge, it's hard to say. The soundest approach is to form your own opinion by reading the scientific literature.
Are sun filters dangerous for corals ?
The second controversy concerns coral reefs. Two filters are the main culprits: oxybenzone and octinoxate, now banned in Hawaii.
While a 2008 study suggested that mineral filters should be preferred to protect corals, research published in 2018 by the Centre Scientifique de Monaco has nuanced this finding: some organic filters have been shown to be relatively safe, while zinc oxide, although a mineral, is harmful to corals (Centre Scientifique de Monaco, 2018). The boundary between organic and mineral filters is not simply that between harmful and harmless.
The problem of nanoparticles.
Mineral filters leave white marks on the skin. To remedy this, marques uses very small particles of zinc oxide and titanium dioxide, known as nanoparticles, which make the cream transparent. Highly criticized in the food industry, nanoparticles pose a different question in cosmetics: being smaller, they could theoretically penetrate the skin better.
Numerous studies have been carried out, and all the results converge: a very small quantity of zinc, in soluble form, can pass through the epidermis, but in proportions much lower than the levels of zinc already present in the body. On the other hand, sunscreens containing nanoparticles are prohibited in spray form, as their inhalation could be harmful.
If you are concerned about nanoparticles, check for the words nano on the list of ingredients (INCI). It indicates which components are involved.
Nanotechnologies applied to cosmetics hold out the promise of interesting advances, but their generalization to skin, hair, nail and lip care still raises questions. Here are the main safety issues identified by research.
Safety concerns
The very small size of nanoparticles enables them to penetrate skin structures, such as hair follicles, and potentially cross the skin barrier. It is this penetration capacity that motivates the caution of many marquess, who avoid highlighting nanotechnologies in their communications.
A sometimes involuntary presence
Nanoparticles are present in many of today's cosmetics, though not always intentionally. Reducing the size of titanium dioxide or zinc oxide to formulate sunscreen unintentionally produces them. Other ingredients are also involved, such as mica or nano-sized fish scales used to create shimmering effects.
Benefits and challenges
Nanoparticles also offer real potential. Their magnetic properties could enable chemotherapy agents to be targeted at tumor sites, reducing exposure of the rest of the body. Challenges remain, however, in controlling ingredients, particle size and their actual ability to cross the skin barrier.
In short, nanocosmetics combine promising benefits with safety uncertainties. Further research is needed to guarantee their safety before they can be confidently recommended by dermatologists. The potential is real, but we still need to ensure that they are used responsibly and without risk to consumers.
Isn't the sun the greatest danger of all ?
Let's put things into perspective. The sun is a proven carcinogen, and a third of all cancers diagnosed in France are skin cancers.
The bottom line is that the sun is a major cause of cancer, and sunscreens are one of the most effective ways of protecting against it.
With some 80,000 cases of skin cancer diagnosed each year in France, the use of sun protection seems essential - without, however, dismissing the potentially harmful effects of certain filters over the very long term.
To date, the sun's proven risk to the skin outweighs the hypothetical risks associated with filters. Numerous studies are underway to better classify each filter. In the meantime, sun protection remains the best-documented preventive intervention.
Things to remember on sun filters.
Are sunscreens endocrine disruptors?
Which filters are prohibited to protect corals?
How do I know if my cream contains nanoparticles?
Should we stop using sunscreen because of these controversies?
Information for educational purposes only. It does not replace medical advice. This article summarizes the scientific data available on sunscreens; research is evolving and many questions remain unanswered. In the event of suspicious skin lesions, or if you have any doubts about the right protection for your skin, consult a dermatologist. No commercial partnership links this page to the marques or filters mentioned. BeautyDecoded - Independent information. Dr Sylvain David, Plastic and aesthetic surgeon - Founder of BeautyDecoded.