Big summer duel: sunscreen versus coral reef 2

Big summer duel: sunscreen versus coral reef

About one fifth of all coral reefs have died in the world in recent years. The main culprits were high water temperatures and more frequent hot water events (aka El Niños), excessive fertilization by droppings or fertilizers from the mainland, decreased light availability of microalgae and sediments in the water. But also chemical pollution, u.a. by means of UV filters made of sunscreens and other cosmetic products we are among the perpetrators. Sunscreen is needed and widely used in the age of ozone holes, increased risk of skin cancer, and longer and more frequent vacations by the sea. As well as UV filters in many body lotions, hair styling products, shampoos, rinses, skin creams, insect repellents and soaps, to protect skin and hair (or selected hair color) from the evil air. That we also need UV radiation, z. B for the production of vitamin D in the skin is another topic.

The origin of all evil

There are three types of UV radiation:

  • UV-A has a wavelength of 320-400 nm and relatively low energy, but 80-90% reaches the Earth's surface. UV-A causes the formation of oxygen radicals (reactive oxygen species) in the skin, causing the three-dimensional structure of the DNA to burst, thereby damaging or killing the cells.
  • UV-B (290-320 nm) is more energetic, but only about 1% of this radiation reaches the Earth's surface. The rest is blocked by the ozone layer. The part that gets into our skin penetrates the cells and is absorbed by the DNA, causing structural damage and cell damage or killing.
  • In addition, there is still UV-C radiation, with wavelengths of 200-290 nm and high energy. They are completely blocked by the ozone layer of the atmosphere, which is why we, as mortals on Earth, do not have to worry about this type of radiation.

UV-A and UV-B cause mutations in the P53 gene suppressor in addition to the general structural damage of DNA mentioned above. The protein encoded by this gene plays an important role in DNA repair or programmed cell death with non-repairable DNA damage. Therefore, we should protect ourselves from UV-A and UV-B radiation. Broad spectrum sunscreens (UV-A and B protection) can reduce the number of precancerous and squamous cell carcinomas, and also protect against chronic damage to keratinized skin (actinic keratosis), which can lead to skin cancer. However, there is little evidence that sunscreen protects against basal cell carcinoma and black skin cancer (melanoma) – even if it is talked about over and over.

Sun cream
Sunscreen and cosmetics with UV filters are an integral part of our lives

Like some preservatives (eg parabens), some UV filters (eg oxybenzone) have been discredited in the past because they affect the hormonal balance and / or immune system of many animals (including mammals like us). The effect is u.a. lower fertility and poorer survival. However, these substances are still used. Over the last ten years or more, more and more studies have shown that UV filters also help with coral deaths, especially along the holiday shores. On a holiday by the sea we want to enjoy the sun, the beach and the water, go swimming, diving, diving, kyte or other surfing. To do this without sunbathing or to reduce the likelihood of malignant skin changes, we apply sunblock. Most sunscreens contain several UV filters, with individual concentrations up to 10% – so that 20 UV% sunscreens can be made from UV filters, the rest are emulsifiers, stabilizers, preservatives, fragrances, etc.