A 27-year-old woman began an experiment on herself early one morning in December 2024. Her laboratory was her childhood bedroom, tucked into a second-floor corner of a pale yellow house in the Boston suburbs. On a bookshelf behind her sat a small stuffed sloth and some favorite books, including “Siddhartha” by Hermann Hesse. Her parents were asleep in the room next door.

Her name is Rebecca, but she goes by Becks. Sitting at her desk in a gray T-shirt, she opened a small plastic bag filled with white powder. The bag was stamped “SR-17018,” and “NOT FOR HUMAN CONSUMPTION.”

She extracted some powder with a red microscooper, poured it onto a digital scale and carefully weighed out 25 milligrams. She gathered this into a blue and white pill capsule and sealed it, and then swallowed the capsule with water. It was 4:27 a.m.

“It’s my turn to be a guinea pig,” Becks wrote in the online diary she was keeping of her experience. In sharing her story with The New York Times, she asked that her last name not be used so potential employers don’t discover her drug history.

Becks had joined the vanguard of a dangerous, highly speculative do-it-yourself approach to getting sober. For a decade, on and off, she had been addicted to various drugs, most recently kratom, an opiate-like substance, which cleared her head and covered up her pain but required constant dosing. She feared the call of fentanyl, which she’d tried a few times.

“Every morning, I woke drenched in sweat from overnight withdrawals. It was a grim existence,” she wrote of her kratom use. She tried various methods to get sober, including three short inpatient detox stays and one monthlong rehabilitation treatment. She had periods of sobriety but couldn’t sustain it.

Then she heard about SR-17018, one of many new and unpredictable synthetic drugs made largely in China and sold online even though it is not approved or shown to be safe, and can pose lethal risks.

Most of these compounds, known as novel psychoactive substances, are designed to get people high. Among those substances, SR-17018 stands virtually alone in that people are using it to try to free themselves of addiction, and some claim it helps.

Excitement about SR-17018 grew after Reddit users discovered a 2019 study suggesting it could free drug-addicted mice of their dependence.

Days before the 2024 presidential election, future Health and Human Services Secretary Robert F. Kennedy Jr. posted a statement on X promising to end the U.S. Food and Drug Administration’s “aggressive suppression” of such alternative therapies as raw milk, ivermectin, psychedelics and, somewhat perplexingly, “sunshine.”

While the post did not explain how the FDA was limiting Americans’ access to the sun, many dermatologists were dismayed when Kennedy abruptly withdrew a proposed FDA rule that would have banned minors from using devices that mimic sunlight — indoor tanning lamps.

The rule, which was withdrawn March 16, would have also required indoor tanning facility users to sign a form acknowledging the risk of cancer, early skin aging and other health effects.

Kennedy’s action comes at a time when many adherents of his Make America Healthy Again movement have adopted regular sun exposure as a core principle of wellness, with social media influencers encouraging followers to abandon sunscreen and build up their “solar callus,” or sun tolerance, instead.

The trend has frustrated many dermatologists, who warn that the damage of frequent sunburns and tans accumulates over a lifetime, and those acquired early in life appear to play a disproportionate role in later risk of skin cancer. The Skin Cancer Foundation notes also that you cannot build up a tolerance to sun exposure and “there is no such thing as a ‘solar callus.’”

Dermatologists have long cautioned that indoor tanning lamps are no less dangerous, since they expose users to ultraviolet light at concentrations far above natural sunlight. Like sunlight, the lamps emit two different types of ultraviolet wavelengths: UVA, which are longer and penetrate more deeply into the skin, and UVB, which are shorter and more easily burn the outer layers.

Both light sources darken skin through the same biological process: UV rays change the structure and chemical profile of DNA in the skin, which then produces more melanin in order to prevent further damage.

A tanning bed session exposes users to UVB rays akin to those at noon at the equator — an intense experience, but at least one with a terrestrial equivalent, said Hunter Shain, an associate professor of dermatology at UC San Francisco. The UVA radiation in a tanning bed is roughly 15 times that found anywhere on the surface of the planet.

“They’re really blasting you with these super physiological doses of UV radiation that you couldn’t even find in a natural environment,” he said.

The World Health Organization counts UV-emitting tanning beds as a Group 1 carcinogen, alongside other known human carcinogens like tobacco cigarettes and asbestos. One study Shain co-authored found that tanning beds accelerate DNA mutations in parts of the body not typically exposed to the sun, leading to a nearly threefold increase in indoor tanners’ lifetime melanoma risk. Rates of melanoma diagnoses have increased by 46% in the last decade.

The tanning lamp rule, which was first proposed in 2015, focused on age as a specific risk factor. Tanning bed usage before the age of 35 is associated with a 75% increase in the risk of melanoma, the most serious and frequently fatal form of skin cancer.

The rule drew more than 9,000 public comments from both physicians and cancer research organizations supporting its implementation and from tanning bed industry representatives and business owners opposed.

Kennedy, who was photographed leaving a Washington tanning salon last year, was ultimately unconvinced of the need to ban minors from such establishments.

“In light of the scientific and technical concerns raised in the comments on the Proposed Rule, concerns regarding possible unintended consequences of certain proposals in the Proposed Rule, and potential alternatives proposed in comments received on the Proposed Rule, FDA is withdrawing the Proposed Rule in order to reconsider the best means for addressing the issues,” Kennedy wrote in the withdrawal letter.

Health and Human Services did not respond to questions about what scientific concerns and unintended consequences Kennedy was referring to.

Nineteen states (including California) and the District of Columbia have already banned people under 18 from indoor tanning salons. Roughly two dozen more have some kind of regulations regarding minors and indoor tanning, such as requiring parental permission or barring only younger children.

The collapse of the proposed federal ban has left many dermatologists disappointed.

“As you can see, when it’s left to the states, the implementation and the guardrails to minimize the exposure to carcinogens are not consistent. … Why are you going to default to a system that we know isn’t working correctly?” said Dr. Clara Curiel-Lewandrowski, chair of dermatology and co-director of the Skin Cancer Institute at the University of Arizona.

Minors in sun-baked Arizona are free to patronize indoor tanning establishments as long as they have a note from their parents. Curiel-Lewandrowski has treated many former sunbed enthusiasts for advanced melanoma in their 20s and 30s, she said.

“There’s a lot of regret. Regret for not knowing more, for not getting more help to understand the threat,” she said. “This is an age group that has a very hard time assessing risk. At that age, they don’t view carcinogens as a real threat.”

The U.S. is a bit of an outlier in its permissive approach to youth indoor tanning. Australia and Brazil have banned cosmetic indoor tanning entirely for people of all ages. Most western European countries ban minors from indoor tanning, as do most Canadian provinces.

“After the proposal lay dormant for more than a decade, I can’t say I was surprised to hear that the FDA withdrew it,” said Dr. Deborah S. Sarnoff, president of the Skin Cancer Foundation. “On the positive side, we made the public very aware of this issue, and this fight is far from over. We won’t be satisfied until tanning beds are banned in this country.”