Fancy soap, liquid soap, shower gel or shampoo, we all use them. Regardless of which cosmetics we use when showering, they all run through the pipes directly into the drain. Then they drive to the sewage treatment plant, where the wastewater is treated and clarified. Unfortunately, a large part of the wastewater polluted with soaps, gels or other cosmetic products ends up in the natural environment, resulting in significant pollution. Here we take a closer look at which pollutants that come from soaps and other hygiene products occur in the environment.
Somewhere over the ocean
Summer, vacation by the sea means sun, water, waves and, for some of us, sunbathing. Long-term exposure to the sun requires adequate skin protection, such as wearing sunscreen with a UV filter. Sunscreens are the best example of chemicals that go straight into the ocean, river, or lake when you swim. They contain substances that absorb or reflect ultraviolet radiation from sunlight, such as organic and inorganic compounds, and these can become serious aquatic pollutants (1, 4).
Some of the most polluting chemicals in sunscreens include oxybenzone, benzophenone-1, benzophenone-8, 4-methylbenzylidene camphor, 3-benzylidene camphor, nanostructural zinc oxide, octynoxate, and octocrylene (5), and that's just the beginning of a very long list of pollutants in cosmetics. These substances have a negative impact on the aquatic environment: coral reefs, fish and others are very susceptible to exposure. These chemicals affect zooplankton and other animals. While fish and chips may be one of the most famous dishes in the world, it turns out that not all fish are this healthy. Experiments have shown that fish that come into direct contact with these substances can produce offspring with significant developmental disorders.
UV filters in sunscreens have also been found to cause the death of animals living in aquatic systems. Under these, Oxybenzone is the most serious mistake. It disrupts the hormonal activity of corals and fish, making them impossible to reproduce. Even minimal concentrations of oxybenzone, on the order of 1 drop, dissolved in 6.5 Olympic swimming pools are harmful. Oxybenzone also negatively affects plankton as food for fish. If it is harmful to fish, it is poisonous to us too. What about the following? Benzophenone-8, Benzophenone-3, and Benzophenone-1 Work similarly to the endocrine disruptor that affects the endocrine system (6). In addition, benzophenones are carcinogenic and can therefore also lead to the development of cancerous tissue (7).
Another compound widely used in UV filters is that 4-methylbenzylidene camphoris also recognized as an endocrine disruptor. It is one of the most commonly found compounds in freshwater fish tissues. It was found to also affect the brain tissue of animals living in water polluted by this compound (8). Its derivation 3-benzylidene Camphor has such toxic effects on living organisms that European trade unions have banned its use in cosmetics (9).
Next is a dangerous connection zinc oxide (ZnO). The powder is used in UV filters, while particles and tiny nanoparticles can dissolve in sea water, in aggregates or in sediments. Its toxicity is very different from the above compounds, but it is dangerous. It can create reactive oxygen species that affect organisms that live in aquatic systems (10). Last but not least – Octinoxate and Octocrylene show neurological toxicity and hormonal disorders (11, 12).
Not just UV filters
What about other chemical substances in cosmetics that easily get into water? Whatever we use to treat our skin sooner or later ends up in the sewers and the environment. For many years Parabens (widely used in creams or other cosmetics) are said to have low toxicity. Unfortunately, the truth is far from it. Parabens can affect the development of the fetus and cause skin redness and allergic reactions in both animals and humans. The structure of these compounds is similar to our hormones. As soon as they interact with our skin, they easily overcome biological barriers. They interact with the body and act as hormones that negatively affect the endocrine system and cause various health problems (1, 2).
Parabens aren't the only example of compounds still found in cosmetics. The next one is Triclosan, used as an antibacterial agent. Triclosan used to be considered non-toxic and it was often added to hand soaps, shampoos, or even types of toothpaste. It later turned out to be dangerous for humans and the environment. A high concentration of Triclosan in the water has a toxic effect on many types of algae and crustaceans. This affects their structure and functioning and can lead to an imbalance in aquatic ecosystems (1).
The list of environmentally harmful compounds is longer than we can imagine (13). Butylated hydroxyanisole (BHA) and butylated hydroxytoluene (BHT) are used as preservatives and antioxidants in cosmetics such as lipsticks and moisturizers. In higher concentrations, they can be toxic to both animals and humans (e.g. kidneys, liver) and allergic (skin irritation) (14). Dibutyl phthalate (DBP) is mainly a component of nail polishes, nail polish removers and hair sprays. Because of its cytotoxicity, it was recently banned in the European Union, although it can still be found in many cosmetics (15). Diethanolamine (DEA) is a foaming agent used to clean cosmetics such as shampoos, soaps, and bath lotions. DEA can cause skin irritation and react with some cancer-causing chemicals. All of these substances mentioned above are harmful to the aquatic environment – they can change the behavior and growth of fish, disrupt the development of animal and vegetable plankton, and lead to the death of aquatic species (13).
There is more …
Do you like scrubs and scrubs? Sometimes abrasive grains in these cosmetics are made from synthetic materials such as plastics. They can release many substances, such as pigments and plasticizers, that can be harmful. Due to their widespread use in cosmetics, they get to rivers, seas and oceans. In addition, microplastics (tiny pieces of plastic under 5 mm) were recently found in Mount Everest and at the North Pole. This is not the end; Microplastic granules are eaten by fish or other aquatic animals, which affects their health (1, 3).
Cosmetics quickly find their way into soil, rivers, oceans, and even drinking water, affecting natural habitat and wildlife. Despite the growing popularity of eco-friendly and organic cosmetics, the cosmetics market is full of harmful compounds. When we use sunscreens, lotions, or makeup cosmetics, we keep in mind that swimming is not a good idea. Thus all of the skin would be flushed directly into the environment.
This article is a joint work of Jakub Hilus (3rd grammar school named Adama Mickiewicza in Katowice), Weronika Urbańska (Faculty of Environmental Engineering, Wrocław University of Science and Technology), Agnieszka Pregowska (Institute of Basic Research, Polish Academy of Sciences). and Magdalena Osial (Faculty of Chemistry, University of Warsaw) as a science message project. Photo Credit – A. Pregowska & M. Osial
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