Only two sunscreen active ingredients currently have enough safety data for the FDA to propose them as Generally Recognized as Safe and Effective (GRASE): zinc oxide and titanium dioxide. The remaining 12 chemical filters sold in the U.S., including popular ones like oxybenzone, avobenzone, and octocrylene, lack sufficient data for a positive safety determination. That doesn’t mean they’re all proven dangerous, but several raise specific concerns worth understanding before you buy your next bottle.
Chemical Filters the FDA Hasn’t Cleared
The FDA’s proposed sunscreen order places 12 active ingredients in a category requiring additional safety data before they can be confirmed as safe and effective. These include oxybenzone, avobenzone, octinoxate, octocrylene, homosalate, octisalate, ensulizole, meradimate, cinoxate, dioxybenzone, padimate O, and sulisobenzone. Two others, PABA and trolamine salicylate, are proposed as explicitly not safe for sunscreen use due to safety concerns.
One reason for the FDA’s caution: all tested chemical sunscreen ingredients absorb through the skin into the bloodstream at levels exceeding 0.5 ng/mL, the threshold that triggers further safety evaluation. In FDA-funded trials, 100% of subjects using oxybenzone-containing sunscreen had blood levels above that threshold within two hours of a single application. Oxybenzone reached peak plasma concentrations between 169 and 258 ng/mL depending on the product type, which is hundreds of times above the safety testing threshold.
Oxybenzone: The Most Scrutinized Filter
Oxybenzone draws more concern than any other sunscreen chemical, and for several overlapping reasons. Studies have found associations between oxybenzone exposure and changes in thyroid hormone levels, testosterone levels, kidney function, and pubertal timing, though regulators note these findings still need validation. Lab studies have also shown oxybenzone can mimic the effect of progesterone on human sperm cells, potentially interfering with fertility by disrupting calcium signaling involved in fertilization.
The European Union’s scientific safety committee reviewed the endocrine disruption evidence and called it “not conclusive” and “at best equivocal.” So oxybenzone isn’t a proven endocrine disruptor in the way that, say, lead is a proven neurotoxin. But the combination of high systemic absorption, hormonal signals in multiple studies, and the availability of alternatives is enough that the American Academy of Pediatrics specifically recommends avoiding oxybenzone in children’s sunscreen.
Octinoxate and Homosalate
Octinoxate (also labeled as octyl methoxycinnamate) shows estrogenic, androgenic, and anti-thyroid activity in both animal and human cell studies. Research in rats found it could disrupt thyroid hormone balance through unusual mechanisms. A 2020 review concluded that topical application doesn’t produce biologically significant hormone changes in humans, but the ingredient remains in the FDA’s “needs more data” category.
Homosalate is another filter flagged in lab studies for interfering with calcium signaling in human sperm, similar to oxybenzone. It’s one of the chemicals Hawaii’s reef-protection law targets, and it appears frequently in everyday sunscreen formulas, often combined with other chemical filters.
Avobenzone: A Stability Problem
Avobenzone is one of the few chemical filters that blocks UVA rays effectively, which makes it hard to replace. Its problem isn’t toxicity so much as instability. When exposed to sunlight, avobenzone shifts between two molecular forms. One absorbs UVA. The other absorbs only UVC (which doesn’t reach the earth’s surface) and breaks down readily. This means your UVA protection can degrade during the time you’re actually in the sun.
Manufacturers add stabilizing ingredients to slow this breakdown, but the degree of protection you’re getting depends on the specific formula. If you see avobenzone listed without stabilizers, the product may lose effectiveness faster than you’d expect from its SPF rating.
Coral Reef and Marine Concerns
Hawaii became the first state to ban the sale of sunscreens containing chemicals harmful to coral reefs, effective January 2021. The National Park Service lists 12 chemicals to avoid for reef protection: oxybenzone, octocrylene, avobenzone, octinoxate, homosalate, octisalate, benzophenone-1, benzophenone-8, OD-PABA, 4-methylbenzylidene camphor, 3-benzylidene camphor, and nanoparticles. If you’re swimming near reefs or in marine environments, this list is broader than most “reef-safe” labels suggest. Many products marketed as reef-safe still contain octocrylene or avobenzone.
Fragrances and Preservatives That Cause Reactions
Active ingredients aren’t the only concern. Sunscreens often contain fragrances and preservatives that trigger allergic contact dermatitis, especially on sun-exposed skin where the barrier is already stressed.
The European Commission identifies 26 fragrance compounds as known allergens, and many appear in scented sunscreens. Common culprits include cinnamaldehyde, citral, geraniol, linalool, limonene, and coumarin. If a sunscreen lists “fragrance” or “parfum” without specifying ingredients, you have no way to know which of these allergens might be present.
Preservatives pose a similar issue. Methylisothiazolinone (MIT) and methylchloroisothiazolinone (CMIT) are well-documented skin sensitizers. Formaldehyde-releasing preservatives like DMDM hydantoin, diazolidinyl urea, and quaternium-15 can also cause reactions. These show up more often in moisturizer-sunscreen hybrids and drugstore formulas. If your sunscreen has ever made your skin itch, burn, or break out in a rash, check for these ingredients before assuming you’re reacting to the UV filter itself.
Spray Sunscreens and Inhalation Risk
Aerosol sunscreens introduce a risk that lotions and creams don’t: you can breathe in the active ingredients. This is particularly relevant for titanium dioxide, which the International Agency for Research on Cancer classifies as “possibly carcinogenic to humans” when inhaled as airborne particles of respirable size (10 micrometers or smaller). California’s Proposition 65 specifically warns about titanium dioxide in aerosolized products like spray sunscreens.
Titanium dioxide in a lotion sits on your skin and poses no inhalation concern. The same ingredient in a spray can enter your lungs. If you use spray sunscreen, spray it onto your hands first and then apply it, especially when putting sunscreen on children’s faces.
Benzene Contamination
Benzene is a known carcinogen that should never be in sunscreen at all. It isn’t a sunscreen ingredient; it’s a contaminant. When the independent lab Valisure tested 294 batches from 69 sun care brands, about 27% contained detectable benzene, with some samples reaching three times the FDA’s accepted limit of 2 parts per million. The contamination appeared scattered across brands and even within different batches of the same brand, suggesting the problem lies in contaminated raw materials rather than any specific formula.
You can’t identify benzene from a label. It won’t be listed as an ingredient. Following product recalls and checking databases like Valisure’s published results is the only way to flag affected products.
What About Zinc Oxide and Titanium Dioxide?
These two mineral filters are the only active sunscreen ingredients the FDA proposes as GRASE at concentrations up to 25%. They work by sitting on the skin’s surface and physically reflecting or absorbing UV rays rather than being absorbed into the body.
Research on nano-sized zinc oxide particles (used in modern mineral sunscreens to reduce the white cast) confirms that while zinc nanoparticles stay in the outermost layer of skin, some zinc does dissolve and migrate into deeper skin layers as individual zinc ions, not as nanoparticles. Importantly, after 48 hours of exposure, no zinc was detected in the fluid beneath the skin above the detection limit of 0.07 micrograms per mL. The particles themselves don’t cross the skin barrier.
For children, the American Academy of Pediatrics recommends zinc oxide or titanium dioxide sunscreens for sensitive areas like the nose, cheeks, ears, and shoulders. If any sunscreen irritates your child’s skin, switching to a mineral formula is the standard recommendation.