Why sunscreens are dangerous

2024 Author: Seth Attwood | [email protected]. Last modified: 2023-12-16 15:55

Science has proven quite convincingly that excess ultraviolet radiation (UV) causes premature aging and skin cancer (including its most dangerous form, melanoma). Therefore, both in Europe and in the United States, people now rarely dare to go to the beach without smearing sunscreen from head to toe. Gradually, this custom is instilled in Russia, which has recently been willingly picking up Western trends in the field of a healthy lifestyle.

Meanwhile, now there are more and more grounds to assert that sunbathing with sunscreens is sometimes no less, and sometimes even more dangerous, than frying in the sun without any protection. Indeed, it is in the United States and Europe, where sunscreens have been used for a long time, that an increase in the incidence of all forms of skin cancer has been observed over the past three decades. If in the early 1970s the incidence of melanoma among the white population of the United States was six cases for every 10 thousand people, then by the beginning of the 2000s it had tripled. In Europe, the incidence of melanoma increased almost fivefold over the same time period. Three hypotheses have been proposed to explain this sad fact. According to the first, the currently observed increase in the incidence of skin cancer is the payback for the craze for the sun in the 1960s and 1970s, since more than one decade can pass between the primary DNA damage and the development of the tumor. Supporters of the second hypothesis blame sunscreens and the chemicals they contain. Finally, a third hypothesis is that it is not sunscreens by themselves, but the way we use them, that transforms them from skin protectors into a risk factor.

Tanning and Vanity

It all began in the 1960s, when white-skinned Caucasians suddenly began to do their best to change the color of their skin, which until recently they were so proud of. The driving force behind this desire was ordinary human vanity. Before the industrial revolution, a significant percentage of the population was employed in agriculture, so labor and poverty were associated with sunburned skin, which speaks of long hours spent in the fields under the open sky. However, in the post-war period (1950s), more and more people began to work in factories and factories where the sun's rays did not penetrate. Now, pale, pigment-free skin was a testament to the need to earn a living through hard work, while tanning was associated with indolence, sun-drenched tennis courts and tropical beaches.

However, it turned out that changing skin color, even temporarily, is not so easy. Someone did it pretty quickly, but someone had to expose the skin to painful tests - it was worth spending a little more time in the sun, and you could get a sunburn, which negated all efforts to acquire the desired tan, since the skin after a burn peeled off.

It was to these sufferers that the cosmetic industry offered a novelty - cosmetics that protected from burns, but did not prevent sunburn. Thanks to new tools, even people who nature had endowed with pale, poorly tanned skin could spend long hours on the beach, eventually achieving the desired tan. As it turned out, this was precisely what could not be done.

THE ABC OF THE ULTRAVIOLET

The ultraviolet radiation reaching the Earth with the sun's rays can be divided into two types - UV-A and UV-B. The fundamental difference between them lies in the radiation energy and the depth of penetration into the dermis. UV-B carries a lot of energy, therefore it quickly causes burns. It was this type of radiation that was blocked by the first sunscreens, and it was this type of radiation that was considered the most dangerous for a long time. However, it is now known that UV-B does not penetrate deeply and all the damage it causes to the skin usually does not have far-reaching consequences. The burnt skin is first covered with blisters, then it comes off with flaps, and with it those cells that have dangerous DNA breakdowns are removed.

The situation is completely different with ultraviolet A, which was initially considered beneficial as it causes sunburn but does not have enough energy to burn the skin. But it turned out that it is UV-A that can penetrate into the deep layers of the epidermis and dermis and damage biological molecules. If earlier people could not sunbathe for too long, since their skin was burned, and usually received only temporary, superficial damage, then with the advent of sunscreens that protected the skin from UV-B radiation, many began to lie on the beach for hours, being exposed to prolonged exposure UV-A.

WHAT IS THE ULTRAVIOLET DANGEROUS

Both UV-B and UV-A rays can be absorbed by biological molecules and cause photochemical reactions leading to free radicals - unstable, highly reactive molecules that lack one electron and are very willing to enter into chemical reactions.

You could say that a free radical is like a young reveler who has no moral obligation and never misses an opportunity to strike up an affair. And if such an "immoral" radical enters into a bond with a "respectable" molecule, then the latter will turn into a free radical and begin to confuse the strict harmony of chemical reactions. In particular, UV-A radiation penetrating deep into the skin can turn collagen molecules, a protein that makes skin smooth and firm, into free radicals. As a result, collagen fibers bind to each other, forming accumulations of defective inelastic collagen, which gradually leads to the appearance of characteristic skin irregularities and wrinkles. They, formed under the influence of UV radiation, appear much ahead of the "schedule", long before the skin begins to age for natural reasons. The consequences of free radical transformation of DNA are even more serious: two parts of the DNA molecule, which have become radicals, can bind to one another, thereby introducing confusion into the genetic code of the cell. Cells that have received DNA damage can develop malignant tumors over time.

SPF - UNRELIABLE INDICATOR

In the 1990s, broad-spectrum sunscreens finally appeared, that is, those that protected not only from UV-B - but also from UV-A radiation. This is where the problem arose. People wanted to tan because tanned skin was still considered beautiful. But if you apply a sunscreen that is not UV-A or UV-B permeable to your skin, you will not get any tanning. Beach goers who dreamed of a "safe" tan began to particularly appreciate sunscreens that had reassuringly high sun protection factor (SPF) values. The fact that even with sunscreens with high SPF values, tanning appeared (albeit slower than without protection), for some reason, did not alarm anyone. And in vain, because in fact the SPF value is a very unreliable indicator of protection efficiency.

SPF allows you to assess how much a given product slows down the appearance of the first reddening of the skin under the influence of UV radiation. For example, if redness appears after 20 minutes without sunscreen, redness appears after 200 minutes with sunscreen that has a protection factor of 10. Since redness of the skin occurs only under the influence of UV-B radiation, the sun protection factor indicates only the effectiveness of UV-B protection.

Nowadays, many manufacturers of sunscreens indicate on their packages the degree of protection against UV-A radiation according to a five-star system: the more stars, the better the protection. But so far SPF remains the most well-known and popular indicator of effectiveness, which is why consumers are paying attention to it. At the same time, few people realize that a sunscreen that has a high SPF, and therefore reliably protects the skin from sunburn, does not necessarily effectively block the path of UV-A radiation. As a result, people can lull themselves with a sense of security and get the long-awaited tan … with all the ensuing consequences.

UNSAFE COCKTAIL

Decades of obsessive advertising for sunscreens have led people, especially in the West, to view them as a must-have component of their beach pastime. However, let's think about what, in fact, we are being offered? And they suggest that we smear ourselves with preparations containing various chemicals, and substitute this cocktail on our skin under the sun's rays. At the same time, it somehow by itself implies that these substances do not react with the skin or with solar radiation, do not penetrate into the blood under any conditions and, in general, demonstrate complete inertia and reliability. But this is not the case.

Sunscreens contain UV filters (also called UV absorbers) - substances that reduce the amount of UV radiation that reaches the skin. Those UV filters that contain particles that reflect and scatter UV radiation are called physical or inorganic UV filters. These include zinc oxide and titanium dioxide. Physical UV filters are non-allergenic or non-irritating to the skin and are broad-spectrum - they block both UV-A and UV-B radiation. In the past, physical UV filters contained large, insoluble particles, so they tinted the skin white. Now the particles of physical UV filters have begun to be made very small - in the micro- and even nano-range, so that they no longer stain the skin.

Another group of UV filters combines substances that can absorb UV radiation due to the peculiarities of their chemical structure. They are called organic or chemical UV filters. Organic UV filters allow you to create products with a protection factor of up to 100 and even higher, it is convenient to include them in a variety of cosmetic forms - creams, gels, sprays, lotions, etc., soak clothes with them, and also add to decorative cosmetics, shampoos, etc. hair sprays. But not all of these substances are safe for the skin.

First of all, organic UV filters are quite common in causing skin allergies and irritation. In addition, some organic UV filters can be photoreactive. This means that if ultraviolet light is shone on such UV filters for a long time, they begin to deteriorate, sometimes releasing free radicals. This means that after a certain time of irradiation in the skin "protected" by such UV filters, more free radicals will be formed than in unprotected skin.

It has now become known that a number of organic UV filters also have hormonal effects. It has been found that they can cause sex reversal and disorders in the development of genital organs in fish, molluscs and other aquatic life. It is not yet clear to what extent the hormonal effects of UV filters are manifested in the human body, but it is already obvious that these substances cannot be called safe and inert.

Perhaps the most shocking fact is that UV filters can enter the bloodstream and build up in the body. For example, according to a recent US study, the common UV filter benzophenone-3 (oxybenzone), which is found in many sunscreens, was found in 96% of more than 2,000 urine samples tested from Americans of different ethnic origins, ages. and gender. At the same time, in the body of women, especially of young age, the content of oxybenzone was, on average, three times higher than in the body of men, and in the blood of white Americans it was seven times higher than that of African Americans.

NATURAL PROTECTION

If not sunscreen, then what? To begin with, human skin is not nearly as vulnerable to UV radiation as sunscreen manufacturers are trying to imagine. You just need to treat this protection reasonably and not make exorbitant demands on it. For example, if a construction helmet has withstood the impact of a falling brick, this does not mean that it is impenetrable. Therefore, if you have the whim of putting on a helmet and pounding yourself on the head with a crowbar, you have only yourself to blame for the consequences. It is the same with the protective systems of the skin. Do not overextend them.

The main protector of the skin is the dark pigment melanin. Moreover, the darker the original (genetically determined) skin pigmentation, the more effective the protection. People with dark skin tend to tan well and rarely get sunburn. With insufficient production of melanin, a person easily burns and hardly achieves at least some kind of tan. Therefore, if you have light, easily burned skin, then you need to be careful with the sun's rays, regardless of whether you are smeared with sunscreen or not. If you have dark skin, you can rely on the protective effect of your own skin pigment. However, too long and intense UV radiation can damage and cover even the skin of Negroids with wrinkles and age spots. And even negroids have melanoma. True, much less often than among white people.

The thinner the skin is, the more damaged it is. Therefore, as a rule, women's and children's skin is more affected by UV radiation. It is especially dangerous to expose the skin of babies under one year of age to excessive UV radiation. However, short sunbathing in the morning will not harm and, on the contrary, will help in the production of the necessary vitamin D.

Another line of defense is antioxidants - substances that neutralize free radicals. They are contained in the stratum corneum of the skin, and are also excreted on its surface with sebum. It should be remembered that many antioxidants are vitamins that are not produced in the body and must be ingested with food. An excellent source of antioxidants - vegetables, fruits and berries, green tea.

If the protection did not work and the skin cells were damaged by the sun, then not all is lost, since the skin is able to correct a significant part of the damage. One of these salutary reactions is the well-known "peeling" of the skin after a sunburn. This "skin change" helps the body get rid of cells with damaged DNA that could otherwise give rise to malignant tumors.

WHO IS TO BLAME AND WHAT TO DO?

As you can see, there are many reasons why the era of sunscreens has simultaneously become an era of an unprecedented increase in the incidence of skin cancer. A role was played by the fact that in the period from the 1970s to the 1990s, most sun lovers either did not use sunscreen at all, or used UV-B protection, which only contributed to a longer stay on the beach, without in any way reducing the risk of skin damage. … In addition, the presence of substances in sunscreens that have the potential to increase skin damage also plays a role. But most importantly, this is still the paradoxical behavior of people who continue to strive for the desired tan, despite all the warnings of scientists and doctors.

Of course, a person needs sunlight. Ultraviolet light provides the synthesis of vitamin D, which is not only important for the proper formation of bones and muscles, but also plays a significant role in the prevention of malignant tumors, maintaining the health of the heart, liver and kidneys, as well as endocrine balance. Sunlight striking the retina of the eye causes the formation of the natural antidepressant melatonin. Moderate UV radiation stimulates skin immunity (excess UV suppresses it), facilitates the course of many skin diseases.

But excess sun exposure can prematurely age the skin and cause other adverse changes. Our great-grandmothers knew about this without any research, they just saw the dark wrinkled faces of peasant women working in the open air. Shady trees, hats with wide brims and gloves that covered arms to the elbows served as protection from the sun. Nowadays, sunscreens with low SPF values can be used for the same purpose. However, if you really want to get some tan, use reasonable caution - avoid the sun at noon, increase your time on the beach gradually, starting from 5-10 minutes a day, and with or without sunscreen, do not irradiate your skin for too long.