UV protection with sunscreen

Ultraviolet (UV) radiation can cause lasting damage to our skin. Readers are therefore strongly advised to observe all of the rules of sun protection – that is, above all, to avoid intense UV radiation and to wear suitable clothing when spending time outdoors. Any skin that still remains uncovered should be protected using sunscreen.

How do sunscreens protect against UV radiation?

Sunsreens and lotions contain soluble (chemical, organic) and/or insoluble (physical, mineral) UV filters. The soluble filters absorb UV radiation and re-emit it as lower-energy, longer-wavelength, thermal radiation. The insoluble filters, for example titanium or zinc oxide absorb, scatter and reflect UV radiation.

Sunscreens can delay the onset of sunburn. There is also scientific evidence to suggest that sunscreens may be able to prevent premature skin ageing and some forms of skin cancer. To do this, sun protection products must protect against both UV-B and UV-A radiation. Protection against UV-A radiation is indicated separately on the label.

What does the sun protection factor mean?

The sun protection factor (SPF) specifies the degree of protection against UV-B radiation and is determined worldwide according to the International Sun Protection Factor (SPF) Test Method. The SPF indicates how much longer a person wearing sunscreen can theoretically expose themselves to the sun without getting sunburnt than would be possible without sunscreen.

Let's assume that a person can be in the sun for 10 minutes at a given UV index without developing sunburn. This is known as the "self-protection time" for that individual and is partly determined by their skin type. If the person uses a sunscreen with an SPF of 20, they can theoretically be outside for 10 minutes * 20 = 200 minutes (just over three hours) at the same UV index without getting sunburnt.

People wearing sunscreen feel safe – but appearances are deceptive. Even sunscreens with a very high sun protection factor whose labels indicate protection against UV-B and UV-A do not provide complete protection. Sunscreens should therefore never be used to extend the period of time spent in the sun arbitrarily. No more than 60% of the theoretical protection time based on the sun protection factor should be utilised.

How much sun cream is necessary?

Despite the use of sunscreen, part of the UV radiation still penetrates into the skin. These products therefore do not protect the wearer against long-term skin damage.

The sun protection factor is specified for a defined sunscreen concentration of 2 milligrams (mg) per square centimetre (cm²). In order to achieve the sun protection factor indicated on the product, 2 milligrams (mg) of the sunscreen must be applied per square centimetre (cm²). For an adult, this is equivalent to four heaped tablespoons for the entire body. If too little is applied or if the quantity of sunscreen is reduced by washing or rubbing, the sun protection factor will be lower.

For example, applying half as much sunscreen can reduce the sun protection factor by two thirds. Sunburn will then occur quickly despite the presence of sunscreen. In order to maintain the effectiveness of the sunscreen, it is important to reapply it continually. However, reapplying only serves to maintain the effectiveness – it does not prolong the effect itself.

Sunscreen checklist

The following list is intended to help you find the right sunscreen for you and use it correctly:

• The sunscreen has a sufficiently high sun protection factor.

  The Federal Office for Radiation Protection (BfS) recommends at least SPF 30. Spending time at high altitudes, on snow, in water, and in very sunny regions requires sunscreen with SPF 50+ (very high).Very high protection is also recommended for children, UV-sensitive people and people with skin types I and II.

• The sunscreen also protects against UV-A.
  The level of protection against UV-A radiation is clearly indicated on the product.
• The ingredients are listed.
  Any hypersensitivity to the ingredients of sunscreens must be taken into account when choosing a sunscreen.
• The sunscreen is applied in good time.
  If the sun cream is applied 20–30 minutes before exposure to the sun, you can be sure that the protection is fully in place.
• The sunscreen is applied in sufficient quantities.
  In most cases, not enough sun cream is used. If you do it right, a 200 ml bottle should be empty after sunscreen is applied to an adult's whole body approx. five times.
• The sunscreen is reapplied regularly.
  At least every two hours and especially after bathing and drying.

What impact can sunscreens have on humans and the environment?

Sunscreens are primarily used to protect people against harmful UV radiation. Among experts and the general public, however, there are also discussions regarding the potential health risks of individual ingredients of sunscreens and their potential harmful effects on the environment.

The German Federal Institute for Risk Assessment (BfR) has compiled a list of the most important questions and answers regarding possible health risks of sunscreens - also regarding phtalates. In its answers, BfR advises that sunscreens available in the European Union (EU) are unlikely to have an adverse effect on health based on current scientific evidence. Products with UV filters can only be sold in the EU if the filters have been assessed and confirmed as being safe for use as UV filters by the European Commission's Scientific Committee on Consumer Safety (SCCS).

With regard to possible environmentally harmful effects of sunscreens, there are indications that substances in sunscreens could be harmful to aquatic organisms such as corals. Even if, for example, the cause of coral mortality (coral bleaching, algae bleaching) is seen by experts as being mainly due to the warming of the oceans caused by climate change, pollutants, including sunscreen substances, appear to exacerbate this problem.

Sunscreens are essential for the necessary UV protection of the skin, especially when bathing, but they are not the only sun protection measure. By avoiding high UV exposure by not staying in the sun for long periods, staying in the shade and staying indoors when UV intensity is high, and by wearing the right clothing, headgear and sunglasses, a lot has already been achieved. And the entry of sunscreen substances into waters can be reduced without reducing your own UV protection by

• wearing suitable UV-protective swimwear that covers as much skin as possible,
• using sunscreens with mineral UV filters only,
• Sunscreens - including waterproof ones - are applied 20 to 30 minutes before bathing so that they can be optimally distributed and absorbed and are not immediately washed off again.