Several common sunscreen ingredients raise legitimate safety concerns, ranging from hormonal disruption to environmental damage. The biggest ones to watch for are oxybenzone, octinoxate, homosalate, and octocrylene. These chemical UV filters have been found to absorb through skin into the bloodstream at levels that exceed federal safety thresholds, and some act as hormone disruptors in laboratory studies. Here’s what the evidence says about each one and what to use instead.
Oxybenzone: The Most Concerning Chemical Filter
Oxybenzone (also labeled as benzophenone-3 or BP-3) stands apart from other sunscreen chemicals in how rapidly and extensively it enters the body. In a clinical trial published in JAMA, participants who applied oxybenzone-containing sunscreen under normal use conditions reached plasma concentrations of 149 to 162 ng/mL after just one day. The FDA’s threshold for requiring additional safety testing is 0.5 ng/mL, meaning oxybenzone exceeded that limit by roughly 300 times.
Beyond absorption, oxybenzone has shown estrogenic activity in lab studies. It mimics estrogen in breast cancer cell lines and, when combined with other UV filters, increased uterine weight in juvenile rats. The European Union has responded by sharply restricting its use: oxybenzone is now capped at 2.2% in body products and banned from spray formulations entirely. The U.S. still permits it at up to 6%.
Oxybenzone is also the chemical most commonly targeted by environmental regulations. Hawaii, Key West, the U.S. Virgin Islands, Bonaire, and Palau have all banned the sale of sunscreens containing it because of documented harm to coral reef ecosystems.
Octinoxate and Thyroid Disruption
Octinoxate (sometimes listed as ethylhexyl methoxycinnamate or OMC) is the other ingredient singled out by Hawaii’s reef protection law. It appears in many lightweight, cosmetically elegant sunscreens and is one of the most widely used UV filters globally.
The concern with octinoxate goes beyond coral. Animal studies show it disrupts both estrogen and thyroid hormone pathways. In fish exposed to octinoxate, males produced vitellogenin, a protein normally associated with egg production, pointing to estrogenic activity. Researchers also found that octinoxate significantly raised thyroxine (a thyroid hormone) in plasma at higher doses and altered the expression of genes involved in thyroid regulation. These findings come primarily from animal and in vitro models, so direct human effects at typical sunscreen exposure levels aren’t fully established, but the pattern across multiple studies is consistent enough to warrant caution.
Homosalate and Octocrylene
These two ingredients get less attention than oxybenzone but have prompted regulatory action in Europe.
Homosalate is permitted at up to 15% in U.S. sunscreens. As of January 2025, the EU restricts it to 7.34% and only in face products, banning it entirely from spray formulations. That’s a significant gap. The EU’s decision reflects concerns about cumulative exposure and hormonal effects: homosalate has demonstrated estrogenic activity in the same cell-line studies that flagged oxybenzone and octinoxate.
Octocrylene absorbs into the bloodstream at levels well above the FDA’s 0.5 ng/mL threshold. In the JAMA trial, plasma concentrations ranged from 0.8 to 3.7 ng/mL after a single day of use. It has also been linked to developmental harm in zebrafish embryos when combined with oxybenzone and octinoxate: higher embryo mortality and lower hatching rates in the next generation. The EU now caps octocrylene at 9% in spray products and 10% in other formulations, which matches the current U.S. limit.
Avobenzone: Lower Risk but Still Absorbed
Avobenzone is the most common broad-spectrum chemical filter in U.S. sunscreens and is often considered a “better” chemical option. It does absorb into the bloodstream, reaching plasma levels of 1.0 to 2.4 ng/mL in clinical testing, which is above the FDA’s 0.5 ng/mL safety threshold. However, it hasn’t triggered the same level of concern for hormonal disruption as the ingredients above. Its main drawback is instability: avobenzone breaks down in sunlight unless stabilized by other ingredients, which is why it’s often paired with octocrylene. If you’re avoiding octocrylene, check whether your avobenzone sunscreen uses a different stabilizer.
Benzene Contamination in Spray Sunscreens
This one isn’t an intentional ingredient but a manufacturing contaminant, and it’s worth knowing about. Starting in 2021, more than 75 spray-style sunscreen and after-sun products were recalled after independent testing found benzene, a known carcinogen, at concentrations above 6 parts per million. Researchers have stated that any detectable level up to 2 parts per million should be cause for concern.
Benzene contamination appears most frequently in aerosol and spray products, not lotions or creams. The FDA has been working with manufacturers to identify contamination sources and pull affected products. If you prefer spray sunscreens, check for recent recalls before purchasing, and consider switching to a lotion or cream formulation to reduce this risk.
PFAS in Sunscreen Products
Per- and polyfluoroalkyl substances, commonly called “forever chemicals,” have been detected in sunscreen products as both active ingredients and impurities. These synthetic compounds don’t break down easily in the body or the environment. Research published in Environmental Science & Technology confirmed that PFAS in sunscreens can penetrate skin and accumulate in tissues over time with repeated application. This is a relatively new area of concern, and product labeling doesn’t always make PFAS content obvious. Water-resistant formulations are more likely to contain them, since PFAS compounds help create that water-repellent barrier.
Retinyl Palmitate: Overstated Risk
You may have seen warnings about retinyl palmitate (a form of vitamin A) in sunscreens. This stems from a National Toxicology Program study that found mice treated with retinyl palmitate and exposed to UV light developed more skin tumors than untreated mice. However, that study was never formally published or peer-reviewed, and the comparison involved a cream containing only retinyl palmitate, not an actual sunscreen. It’s not an appropriate model for how the ingredient behaves in a real product. While there’s no strong reason to seek it out in a sunscreen, the evidence for avoiding it is weaker than for the chemical filters listed above.
What to Use Instead
Mineral sunscreens using zinc oxide or titanium dioxide as their active ingredients remain the safest well-studied option. These sit on top of the skin and physically block UV radiation rather than absorbing it chemically. The main concern people raise about mineral sunscreens is nanoparticle size, since smaller particles spread more easily and leave less of a white cast. Research on this is reassuring: a study involving repeated application of nano-sized zinc oxide to human volunteers found that the particles accumulated on the skin surface and within skin furrows but did not penetrate into the living layers of skin and caused no cellular toxicity.
Small amounts of zinc ions did reach the viable epidermis, but at levels that did not produce local toxicity. For practical purposes, nano or non-nano zinc oxide and titanium dioxide sunscreens are both considered safe for adults and children over six months.
One ingredient to watch for in the near future is bemotrizinol, a chemical filter that has been used safely in Europe, Asia, and Australia for years. The FDA has proposed adding it to the approved U.S. sunscreen ingredient list at concentrations up to 6%, which would make it the first new chemical filter option considered generally recognized as safe and effective in the U.S. in decades. If approved, it would offer broad-spectrum protection without the absorption and hormonal concerns associated with oxybenzone and octinoxate.
Quick Reference: Ingredients to Check For
- Oxybenzone (benzophenone-3): Absorbs at 300x the FDA safety threshold. Estrogenic activity. Banned in multiple reef regions.
- Octinoxate (ethylhexyl methoxycinnamate): Thyroid and estrogen disruption in animal studies. Banned alongside oxybenzone in Hawaii and other locations.
- Homosalate: Permitted at twice the EU limit in the U.S. Estrogenic activity in lab studies.
- Octocrylene: Absorbs above the FDA safety threshold. Linked to developmental harm in aquatic species.
- Benzene (contaminant): Not an ingredient but found in recalled spray products. Choose lotions or creams to reduce risk.