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New suspects: sunscreens and parabens

R+D CSIC 30 years

Sunscreens are a recent addition to the list of pollutants to monitor. Thirty years ago, the technology to detect them and the techniques to see their effect on living organisms did not exist, but neither was there any thought of looking for them. The exponential growth of personal care and hygiene products incorporating sunscreens has triggered research into them.

A study carried out a few months ago has shown that Posidonia meadows in the Mediterranean have been impacted by sunscreen pollution for the last 20 years. Image: CEAB/CSIC

A recent study published in the Marine Pollution Bulletin in April 2022 showed that posidonia meadows in the Mediterranean sea have been impacted by sunscreen pollution for 20 years. The study, with the participation of Silvia Diaz-Cruz, a researcher at IDAEA-CSIC, was carried out in Mallorca.

How do scientists know that sunscreen compounds have been accumulating into the posidonias for 20 years? "In the rhizomes of these marine plants", the researcher explains, "we can see their growth process and what they have been accumulating over the years".

Sunscreens are "new" pollutants. They include compounds such as oxybenzone, avobenzone and benzophenone-4, all of which are molecules that absorb UV radiation. Researchers are currently working to clarify the effects of these molecules on living organisms. In places like Hawaii, Palau, and the entire Mediterranean coast, with a large influx of tourists, there is a high level of pollution by sunscreens, which in turn, can have serious effects on ecosystems.

Another study carried out in Hawaii, with Diaz Cruz as a co-writer, analysed this new type of pollutants. As the study demonstrated, beach shower areas were identified as a new source of sunscreen emissions (Journal Hazard Mater, 2022) and, as a consequence, sea water of the coral reefs in the area presented a high risk of sunscreen for various coral species (Chemosphere, 2021). These studies have led to a ban on the use of some of these substances in Hawaii and Palau.

One of the shower areas at a location in Hawaii that were detected as sources of sunscreen contamination.

Aerial view of the location of the shower area and the points where sunscreen contamination was detected

There is more knowledge on the impact on living organisms

The group led by Diaz-Cruz also analyses the presence of sunscreens in humans, placenta, breast milk and umbilical cord. The presence of these compounds has been linked to endometriosis, poor semen quality, low birth weight, early puberty and obesity. Also, the scientists analyse the presence of these pollutants in the environment: wastewater, flora, fauna and agricultural products. Another research line is detection and control of parabens, such as methylparaben or benzylparaben, substances used to extent the shelf life of products. Some of these compounds, which can be found in cosmetics, are endocrine disruptors and have been related to the development of breast cancer. 

Scientists study the presence of sunscreens in human placenta, breast milk and umbilical cords, compounds that have been linked to endometriosis, poor semen quality, low birth weight and obesity

Nowadays, we have more available information on the substances that are introduced into the market, explains Silvia Diaz. "We have the REACH regulation, which came into force in 2007 and makes it compulsory to analyse and assess the risk of the chemical substances that are produced". According to REACH regulation, companies must identify and manage the risks associated with the substances they manufacture and market in the European Union.  They must demonstrate how to use these substances safely and communicate all information on risk management measures to the parties involved.

Silvia Diaz-Cruz points out: "in the past, products were manufactured only on the basis of need; now the environmental impact is also taken into account". In addition, the current water shortage is a determining factor. "In the past, water was not reused as now. That's why we need to go further in water purification so that it becomes a resource again and not a waste product". In this sense, progress in analytical techniques for the determination of pollutants has been a great help: they have much more sensitivity and resolution than three decades ago, which makes it possible to detect and also identify molecules with greater precision and at much lower concentrations.

References:

Mediterranean seagrass Posidonia oceanica accumulates sunscreen UV filters. Nona S. R. Agawin et al, Marine Pollution Bulletin. https://doi.org/10.1016/j.marpolbul.2022.113417

Beach showers as sources of contamination for sunscreen pollution in marine protected areas and areas of intensive beach tourism in Hawaii, USA.
Downs CA et al. Hazard Mater. 2022 doi: 10.1016/j.jhazmat.2022.129546

Oxybenzone contamination from sunscreen pollution and its ecological threat to Hanauma Bay, Oahu, Hawaii, U.S.A. Downs CA et al, Chemosphere. 2022 doi: 10.1016/j.chemosphere.2021.132880.