In 2019, the US Food and Drug Administration (FDA) released a study showing that chemicals in sunscreens enter the human body in potentially dangerous doses.
"Vesti. Nauka" spoke in detail about this work. Recall that in the course of a study in the blood plasma of volunteers, after one day of using sunscreens (lotion, cream and two types of spray), the concentration of four key substances was exceeded: avobenzone, oxybenzone, octocrylene and mexoryl (or ekamsul).
Concentrations exceeded 0.5 nanograms per milliliter. This is the threshold set by the FDA for no additional safety testing.
Experts, however, were not convinced that these concentrations of these substances were associated with risks to human health.
In addition, the study was criticized for its small sample size (only 24 people participated).
Therefore, the FDA specialists did another job. They expanded the sample size and the list of substances that they studied in the blood of people.
The new trial involved 48 healthy men and women. Their average age was 38 years.
The volunteers were randomly assigned to one of four sunscreen sprays or lotions. Participants covered up to 75% of their body with them once on the first day of the experiment and four times a day for the next three days.
A total of 34 blood samples were taken from each volunteer during the 21 days of observation.
Analyzes showed that the majority of the participants absorbed the active ingredients at levels above the FDA-set threshold after a single use.
We are talking, in particular, about six substances: avobenzone, oxybenzone, octocrylene, homosalate, octisalate and octinoxate.
Peak concentrations of oxybenzone ranged from 180.1 to 258.1 nanograms per milliliter, while the other five ranged from 3.3 to 23.1 nanograms per milliliter, depending on the type of sunscreen.
At the same time, the active components of sunscreens were often retained in the body: in more than 50% of the volunteers, the levels of avobenzone, octisalate and octinoxate remained elevated for seven days, while the concentrations of homosalate and oxybenzone remained above the threshold level for three weeks.
The most common unwanted side effect was rash, with 14 participants.
Thus, the specialists confirmed and expanded the results of the previous work.
However, the question of what kind of danger substances in the composition of sunscreens can pose is still open.
According to FDA officials and oncologists, there is no evidence yet that the designated substances are harmful. (Although avobenzone is under suspicion of Russian researchers: experiments have shown that it decomposes into harmful chemical compounds in chlorinated water under the influence of sunlight.)
Meanwhile, there is no doubt about the danger of ultraviolet radiation: its effect is fraught not only with burns and accelerated aging of the skin, but also with quite real cancer.
Of course, the new results are worrisome and suggest more research is needed.
By the way, about the limitations of a new job. The current test was conducted in a laboratory setting and it is not known how exposure to heat and sunlight in the open air would affect the absorption of active ingredients in sunscreens by human skin.
At this stage, experts are urging the public to continue to use sunscreen when needed.
Toxicologist Robert Chilcott at the University of Hertfordshire noted that the FDA's findings are somewhat anticipated because the skin is not an insurmountable barrier and can absorb chemicals from products applied to its surface.
"This does not mean that sunscreens are unsafe to use. But manufacturers must conduct appropriate safety tests," said Professor Chilcott, who was not involved in the new work. associated with overexposure to the sun on unprotected skin."
Recall that sunscreens should be recommended to people by a dermatologist. The authors of the accompanying editorial emphasize that specialists, when drawing up such recommendations, should remember the balance of risk factors and benefits for each individual.
In other words, clinicians must determine whether the benefits outweigh the risks to a particular patient. This balance can be different depending on factors such as skin type and age, frequency and duration of application of the product.
More details about the new study are provided in an article in the journal JAMA.