is it safe to make your own?

The use of natural and organic products for skin care is becoming more and more popular – and this includes sunscreen. Many websites, including Pinterest and Instagram, offer user recipes for homemade sunscreens.

Judging by the comments, the growing interest in hand-held sunscreens is due to the fact that some people are worried about the chemicals found in store-bought sunscreens and think that natural products mixed at home will be more effective for protect them from the harmful rays of the sun.

The fear comes from recent news that some sunscreen ingredients, such as oxybenzone and octinoxate, seem to disrupt hormones. In addition, the use of sunscreens containing these ingredients may result in their accumulation in the body at levels exceeding the safety threshold established by the US Food and Drug Administration (FDA).

The widespread use of oxybenzone and octinoxate has also been reported to be harmful to the environment and marine life.

Most homemade sunscreen recipes contain ingredients such as shea butter and cocoa butter, as well as coconut oils, almond, avocado, lavender and vitamin E According to the authors of these recipes, the sun protection factors (SPF) of these ingredients are between four and six. These SPF values, if true, are not enough to protect the skin from the harmful effects of sunlight.

Some recipes include essential oil of carrot seed, for which the authors claim to have a SPF of 35-40. But this is unlikely, given the small amount used in these recipes.

The only valid component suggested in the recipes is perhaps zinc oxide. The recipes recommend using only "uncoated", "non-nano" and "non-micronized" zinc oxide preparations in order to avoid harming the environment. It's perfect as long as the size and proportion of "non-nano" and "non-micronized" zinc oxide particles are carefully studied and tested to provide an effective filtering effect of the sun.

Protection at all?

The most harmful rays of the sun are ultraviolet (UV) rays, including UVB and UVA rays. UVBs have a shorter wavelength and do not penetrate far into the skin, but they are very dangerous because they can alter the DNA of skin cells and cause skin cancer.

UVAs have a longer wavelength and can penetrate much deeper into the skin. UVA can cause the formation of harmful reactive oxygen molecules called "free radicals". These molecules can damage the fat, proteins and DNA of the skin, thus harming the normal functioning of skin cells.

Store-bought sunscreens contain approved UV filter compounds that block both UVA and UVB rays. Zinc oxide is one of these UV filters. It has been the subject of numerous tests to determine the most effective size to block harmful rays. It is not clear if the recommended zinc oxide powder for homemade recipes respects the recommended size or proportion.

Store-bought sunscreens also contain antioxidants, such as vitamins E and C, which neutralize the harmful effects of free radicals once they are formed by UVA rays in the skin. Here, DIY sunscreens have certain advantages because they often contain natural oils, such as vitamin E, which possess antioxidant properties.

All sunscreens on the market have been extensively tested to demonstrate full coverage of UVA and UVB, appropriate antioxidant properties and water resistance. The FDA and the European Commission have recommended a sun protection factor of 15 to 29 (and 30 to more than 50 for high protection) for moderate skin protection.

The SPF mainly reflects protection against UVB rays. For UVA rays, it is also necessary for the index "UVA protection index" to be inscribed on the solar protection containers. According to the European recommendation, UVA protection for each sunscreen should represent at least one third of the labeled SPF. A product that meets this requirement will be labeled with a UVA logo – the letters "UVA" printed in a circle.

Consumers should read the label and apply the recommended thickness of 2 mg per square centimeter of skin. It is the thickness at which the SPF and UVA protection index is established by the FDA and EU recommendations to reduce the risk of skin cancer, especially in fair-skinned people.

These facts highlight the danger of using a homemade sunscreen that lacks proper testing and protection. In addition, homemade recipes are not prepared in a sterile environment and are therefore prone to bacterial and fungal contamination, which can cause skin infections. The bottom line is simple: people do better with store-bought sunscreens.

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This article is republished from The Conversation under a Creative Commons license. Read the original article.