Several chemical UV filters found in common sunscreens have raised safety concerns, primarily because they absorb through the skin and into the bloodstream at levels that prompted the FDA to request more safety data. The two ingredients the FDA has proposed as officially “not safe and effective” are PABA and trolamine salicylate, though neither is sold in sunscreens anymore. The bigger question for most people involves the chemicals still on shelves: oxybenzone, avobenzone, homosalate, octinoxate, octisalate, octocrylene, and ensulizole.
Here’s what the evidence actually shows about each one, and what it means for your sunscreen choices.
Why the FDA Flagged 12 Ingredients
The FDA sorts sunscreen ingredients into three buckets: safe and effective, not safe and effective, and “we need more data.” Only two mineral filters, zinc oxide and titanium dioxide, landed in the safe category. Two older chemicals, PABA and trolamine salicylate, were deemed not safe. The remaining 12 chemical filters, including most of the active ingredients in popular sunscreens, sit in that middle category where the FDA says it can’t make a final safety determination without additional information.
That doesn’t mean those 12 chemicals are dangerous. It means the FDA doesn’t yet have enough modern safety data to confirm they’re harmless when used daily, as most dermatologists now recommend. The concern is straightforward: these chemicals pass through your skin and reach your blood, and for some of them, the levels are high enough to warrant a closer look.
Oxybenzone: The Most Studied Concern
Oxybenzone is the chemical UV filter with the most evidence against it. In a randomized clinical trial published in JAMA, a single application of sunscreen lotion produced blood levels of oxybenzone reaching 94.2 nanograms per milliliter. With repeated use over several days, levels climbed to 258.1 ng/mL in lotion users. The FDA’s threshold for when a chemical needs further safety testing is just 0.5 ng/mL, meaning oxybenzone exceeded that limit by roughly 500 times after maximal use.
The hormonal data is what makes those blood levels worrying. A systematic review found that higher oxybenzone concentrations in the body were associated with lower levels of free thyroid hormones. In reproductive studies, male adolescents with the highest oxybenzone exposure had roughly 37 to 39 percent lower total testosterone compared to those with the lowest exposure. Other studies linked it to decreases in follicle-stimulating hormone and luteinizing hormone, both of which play roles in fertility. These are associations from observational research, not proof that oxybenzone caused the hormonal shifts, but the pattern is consistent enough to be taken seriously.
Oxybenzone is also the chemical most strongly linked to coral reef damage. Hawaii banned the sale of sunscreens containing oxybenzone, octocrylene, and homosalate, allowing only mineral formulas. The Republic of Palau enacted a similar ban years earlier.
Octinoxate, Homosalate, and Octocrylene
Octinoxate (sometimes listed as octyl methoxycinnamate) is one of the most common UV filters worldwide. Despite concerns about absorption, the clinical evidence on hormonal effects is more reassuring than for oxybenzone. A systematic review concluded that topical application of octinoxate does not have a biologically significant effect on thyroid or reproductive hormone levels. It’s still in the FDA’s “needs more data” category, but the existing human studies haven’t shown clear harm.
Homosalate is a different story. In laboratory screening, it triggered activity in seven estrogen receptor assays, four androgen receptor assays, and one thyroid assay. It showed estrogenic effects and weak anti-androgen activity in cell studies. The concentrations needed to trigger those effects in a lab dish are higher than what’s typically measured in human blood after sunscreen use, but the breadth of hormonal pathways it activates is notable. The FDA has not cleared it as safe.
Octocrylene showed estrogen receptor binding and a mix of androgenic, anti-androgenic, and anti-estrogenic activity in lab studies. It also absorbs into the bloodstream, with plasma concentrations ranging from 2.6 to 38.7 ng/mL in studies of normal use. An additional concern: octocrylene can degrade over time into benzophenone, a compound with its own potential toxicity, which means older sunscreen products may pose more risk than fresh ones.
Benzene Contamination in Spray Sunscreens
In 2021, independent testing revealed that dozens of sunscreen products contained benzene, a known human carcinogen that has no safe level of exposure. More than 75 spray-style sunscreens and after-sun products were recalled. Some contained benzene at concentrations above 6 parts per million.
Benzene was never an intentional ingredient. The leading theory is that certain compounds in aerosol propellants react with each other to form benzene during manufacturing or storage. The contamination has been most strongly associated with spray-format products, not lotions or creams. If you prefer spray sunscreen for convenience, checking recall lists before buying and switching to lotion-based formulas eliminates this particular risk.
Preservatives That Cause Skin Reactions
Beyond the active UV-filtering ingredients, some sunscreens contain preservatives that trigger allergic contact dermatitis. Methylisothiazolinone is one of the most significant emerging allergens in personal care products, including sunscreens, moisturizers, and baby wipes. The rate of allergic reactions to this preservative has been climbing steadily as manufacturers have increased its use. If you develop a rash from sunscreen that doesn’t seem related to sun exposure, this preservative is a common culprit worth checking the ingredient list for.
What About Mineral Sunscreens?
Zinc oxide and titanium dioxide are the only two sunscreen ingredients the FDA currently considers safe and effective. They work by sitting on top of the skin and physically reflecting UV rays rather than absorbing them. Skin penetration studies show that nanoparticles of these minerals can settle into the outermost dead skin layers and hair follicles but only sporadically reach living skin cells, and in very low concentrations.
The one caveat involves inhalation. The International Agency for Research on Cancer classified titanium dioxide as a possible carcinogen based on studies where rats exposed to high concentrations of the dust developed respiratory tract cancers. This is relevant for powdered or spray mineral sunscreens, not for lotions and creams. If you’re using a mineral sunscreen in lotion form, the inhalation concern doesn’t apply.
For nursing mothers, mineral sunscreens are generally considered the better option, since zinc oxide and titanium dioxide don’t absorb meaningfully into the bloodstream and therefore aren’t expected to transfer into breast milk. Published data on infant exposure levels from chemical UV filters in breast milk is essentially nonexistent, which is itself part of the data gap the FDA is trying to close.
Choosing a Safer Sunscreen
If you want to minimize your exposure to the chemicals with the most evidence of concern, the simplest approach is switching to a mineral sunscreen containing only zinc oxide, titanium dioxide, or both. Modern mineral formulas have improved dramatically and no longer leave the thick white cast that made older versions unpopular, especially those marketed as “micronized” or tinted.
If you prefer chemical sunscreens for their lighter feel or better performance under makeup, avoiding oxybenzone specifically eliminates the ingredient with the strongest evidence of hormonal activity. Many mainstream brands have already reformulated to remove it. Checking the active ingredients panel on the back of any sunscreen takes a few seconds and tells you exactly which UV filters are inside.
What the evidence doesn’t support is skipping sunscreen entirely. UV radiation is a confirmed carcinogen, and sunscreen use reduces the risk of melanoma and other skin cancers. The goal is choosing a formula that protects your skin without introducing unnecessary chemical exposure, and for most people, that means reading the label and picking mineral filters when possible.