Does sunscreen cause cancer? What are the carcinogenic ingredients in sunscreen?

Summer is coming soon, and it’s time to start buying sunscreen again. But I heard that sunscreen contains carcinogenic ingredients and using too much can cause cancer! ! !

Does Sunscreen Cause Cancer?

A new study published in the journal Toxicological Chemistry by the French National Center for Scientific Research and Sorbonne University pointed out that sunscreen left for a long time will produce carcinogens and increase the risk of cancer.

The researchers purchased about 15 common sunscreens and anti-aging creams on the market from the United States and France, and artificially aged them to simulate the situation after one year. The results showed that Octocrylene, a chemical ingredient often used in sunscreens and anti-aging skin care products, deteriorates after a period of time and produces the compound Benzophenone, the content of which accumulates rapidly as the product ages and deteriorates. Sunscreen products that do not contain benzophenone often do not contain the common sunscreen ingredient octocrylene.

That is, octocrylene, a common ingredient in sunscreen, produces the carcinogenic substance benzophenone over time.

It is understood that benzophenone is the "culprit" that causes contact dermatitis. It may cause urticaria and allergic reactions, and also interfere with endocrine. The International Agency for Research on Cancer (IARC/Iarc), an agency of the World Health Organization, has classified benzophenone as a "Group 2B product that may be carcinogenic to humans". In the United States, benzophenone is banned as a food additive and in cosmetics.

The researchers said that before the study was released, octocrylene had already caused a lot of controversy. In some places, including Hawaii and the U.S. Virgin Islands, octocrylene has been banned because it is harmful to corals.

Of course, this does not mean that people cannot use skin care products such as sunscreen. After all, the damage caused by ultraviolet rays may be greater. Researchers said that when using sunscreen, you must pay attention to the shelf life and best before date, and try not to use skin care products that have been stored for too long.

Carcinogenic ingredients in sunscreen

1. The U.S. Food and Drug Administration conducted an experiment;

2. 24 volunteers applied sunscreen or spray 4 times a day for 4 consecutive days, covering 75% of the skin each time;

3. Blood tests on volunteers revealed that four active ingredients, avobenzone, benzophenone derivatives, octocrylene and benzylidene camphor derivatives, had penetrated into the volunteers’ blood in just one day; among them, benzophenone-3 was more harmful;

4. It is recommended that you choose sunscreen not only by looking at the SPF value but also the ingredients.

Let’s first understand these 4 ingredients.

"Benzophenone derivatives" are the most harmful of these four ingredients

That is benzophenone-3. Generally speaking, benzophenone-3 will be mentioned when mentioning sunscreens with higher risk factors.

The use of benzophenone-3 is permitted, but there is a certain consensus that it is quite harmful. Although it is a broad-spectrum UV absorber, it can induce photosensitivity, is absorbed in large quantities by the skin, and has estrogen-like effects, which can interfere with the normal development of the reproductive system.

EWG defines it as an extremely harmful sunscreen agent, and the EU also adjusted the allowed addition amount of benzophenone-3 from 10% to 6% in 2017.

Octocrylene is known to have very low toxicity and no exact data is available.

Octocrylene provides partial protection against both UVA and UVB. The United States has very strict requirements on chemical sunscreens, and there are relatively few types that can be used, but octocrylene is allowed to be added, and this ingredient is added to many sunscreens.

In fact, compared with other chemical sunscreens, octocrylene is relatively safe and its toxicity is known to be very low. There are reports that octocrylene will release free radicals when exposed to sunlight, but there is no exact data, so there is no need to be afraid of it.

Avobenzone is a very common chemical sunscreen.

Avobenzone, written as "Butyl Methoxydibenzoylmethane" in the ingredient list of sunscreen products in my country, is contained in many common sunscreens, so it is also one of the common chemical sunscreens.

It can effectively absorb UVA. As for its harmfulness, there have not been many reports. However, due to its poor stability, it will slowly decompose after being exposed to ultraviolet rays and lose its sun protection effect, so it is used in combination with some other sunscreens.

"Benzal camphor derivatives" cannot prove that they are particularly harmful

Benzylidene camphor derivatives are a relatively new UVA protective agent, which is written as "terephthalylidene dicamphor sulfonic acid" in the ingredient list in my country.

Benzylidene camphor derivatives are known as one of the most effective UVA sunscreen ingredients. In addition, they are relatively stable and are approved for use by the U.S. FDA. So far, no reports on their harmful effects have been found.

What kind of sunscreen should I buy?

1. Sunscreen products with different SPF or PA values ​​need to be selected according to the specific target to achieve the purpose of sun protection.

2. The higher the SPF of a product, the more sunscreen is added, and the greater the irritation to the skin. Therefore, if you go to work on a normal day, you can choose products with SPF15 and PA+. If you are doing outdoor sports, it is advisable to choose products with SPF25~SPF35 and PA++. If you are going to the beach to swim, you can choose SPF35~SPF50, PA+++.

3. After completing your daily skin care steps, you can apply sunscreen and then your daily makeup. However, like other skin care products, sunscreen needs a certain amount of time to be absorbed by the skin, so you should apply sunscreen 10 to 20 minutes before going out.

Which sunscreen should I buy, 30 or 50?

Normally, you can use SPF30 sunscreen. If you stay outdoors for a long time, you can use SPF50 sunscreen. More and more people have noticed the importance of sun protection, especially for women. Sun protection is not as simple as preventing sunburn, because sun protection can also prevent tanning and slow down aging. So what kind of sunscreen should you choose when buying it? Many people apply sunscreen twice a day and rarely go out, so SPF30 sunscreen is enough. The ultraviolet rays at the seaside are very strong. If you are going to the beach, you must choose a sunscreen with a higher SPF factor. It is recommended to choose a sunscreen with SPF50+, and you also need a product with UV protection function to protect against ultraviolet rays. It is not the case that the higher the SPF value, the better. The higher the SPF value, the greater the burden it will bring to the skin.