Octocrylene: The Sunscreen That Degrades Into a Potential Carcinogen
It's in thousands of sunscreens. The FDA says it's NOT GRASE. And scientists found it breaks down into benzophenone—a possible carcinogen. The longer your sunscreen sits on the shelf, the more benzophenone it contains.
Quick Version
- What it is: UVB/short-wave UVA filter used up to 10% in sunscreens
- The problem: Degrades into benzophenone (IARC Group 2B - possibly carcinogenic to humans)
- The twist: Benzophenone concentration increases over product shelf life
- FDA status: NOT GRASE - insufficient data to determine safety
- EU status: Restricted to 9-10% now; pending ban proposal at 0.001% for environmental concerns
- Systemic absorption: Exceeds FDA's 0.5 ng/mL threshold on first application
What Is Octocrylene?
Octocrylene (INCI: Octocrylene, CAS: 6197-30-4) is one of the most widely used organic UV filters in sunscreens globally. You'll find it under trade names like Parsol 340, Uvinul N-539, Neo Heliopan 303, and Escalol 597.
It absorbs UVB radiation (280-320 nm) and short-wave UVA, but its real superpower is stabilizing other UV filters—particularly avobenzone, which degrades rapidly under UV exposure. Without stabilizers like octocrylene, avobenzone-based sunscreens would lose significant protection within hours.
That functionality made octocrylene nearly ubiquitous. The problem is what happens to it over time.
The Benzophenone Problem
In March 2021, researchers led by Craig Downs published findings in Chemical Research in Toxicology that changed how we look at octocrylene:
Key Finding:
Octocrylene degrades via retro-aldol condensation to produce benzophenone. Critically, the concentration of benzophenone increases over the product's shelf life.
Downs CA, et al. (2021). Chemical Research in Toxicology. DOI: 10.1021/acs.chemrestox.0c00461
Benzophenone is classified by IARC as Group 2B: Possibly carcinogenic to humans. The US FDA has zero tolerance for benzophenone as a food additive. And here it is, forming spontaneously in your aging sunscreen.
This isn't theoretical. Researchers tested commercial sunscreen products and found measurable benzophenone—with concentrations increasing the longer products sat on shelves.
FDA Says NOT GRASE
In February 2019, the FDA proposed new sunscreen rules. Their conclusion on octocrylene:
FDA Classification:
Category III – Additional data needed. NOT Generally Recognized as Safe and Effective (GRASE).
As of 2025, only two sunscreen ingredients are FDA-GRASE: zinc oxide and titanium dioxide (both up to 25%). Octocrylene is among 12 ingredients for which FDA has requested additional safety data before making a final determination.
The Systemic Absorption Studies
The FDA's concern isn't arbitrary. In 2019 and 2020, Matta et al. conducted randomized clinical trials measuring sunscreen ingredient absorption into blood plasma.
FDA Threshold: 0.5 ng/mL
The FDA established that if a sunscreen ingredient exceeds 0.5 ng/mL in plasma, additional safety studies are required:
- Nonclinical toxicology assessment
- Systemic carcinogenicity studies
- Developmental and reproductive studies
Octocrylene Results
| Formulation | Octocrylene % | Cmax (ng/mL) | Threshold? |
|---|---|---|---|
| Spray 1 | 2.35% | 2.9 ng/mL | 5.8x exceeded |
| Spray 2 | 10% | 7.8 ng/mL | 15.6x exceeded |
| Lotion | 6% | 5.7 ng/mL | 11.4x exceeded |
| Cream | 10% | 5.7 ng/mL | 11.4x exceeded |
Data: Matta et al. (2019). JAMA. DOI: 10.1001/jama.2019.5586
Every single formulation exceeded the FDA threshold on Day 1 after just 4 applications. In follow-up studies, plasma concentrations remained above 0.5 ng/mL through Day 10 in over 67% of participants.
The half-life? Between 43 and 84 hours. This means octocrylene accumulates with repeated use.
EU: Currently Restricted, Possibly Banned
In the EU, octocrylene is currently permitted under Annex VI, Entry 10 of Regulation (EC) No 1223/2009. Recent restrictions (July 2022) lowered limits:
- Propellant sprays: 9% maximum (reduced from 10%)
- Other products: 10% maximum
The SCCS concluded that at 9-10%, the Margin of Safety remains above 100 for most use scenarios. However, when you combine propellant spray at 10% with face cream, hand cream, and lipstick (all at 10%), the aggregate Margin of Safety drops to 92—below the acceptable threshold.
The Environmental Ban Proposal
In September 2025, ECHA launched a public consultation on a far more dramatic measure:
Proposed EU Restriction:
Ban cosmetic products containing octocrylene at ≥0.001% w/w
At 0.001%, octocrylene is functionally useless as a UV filter. This would effectively phase out octocrylene entirely from EU cosmetics.
The rationale? Environmental toxicity. Key data points:
- PNEC (freshwater): 0.266 µg/L
- Risk Characterization Ratio (freshwater bathing): 744 (anything above 1 indicates unacceptable risk)
- High chronic aquatic toxicity, persistence, and bioaccumulation
The consultation closes March 2026. If adopted, there would be a 24-month implementation period.
What About Photoallergy?
Octocrylene also has a peculiar allergy profile. Photocontact allergy (reactions requiring UV exposure) is more common than regular contact allergy.
The strange part: over 80% of people with octocrylene photoallergy have a history of topical ketoprofen (an NSAID) photoallergy. The mechanism is unknown—the chemicals have completely different structures. But the cross-reactivity is so strong that anyone with ketoprofen allergy should avoid octocrylene.
Contact allergy to octocrylene is more common in children (from sunscreen use), while photoallergy is more common in adults (with ketoprofen history).
The Complete Safety Picture
| Parameter | Value | Interpretation |
|---|---|---|
| Dermal absorption | 0.15% (mean) | Low |
| Plasma half-life | 43-84 hours | Accumulates |
| Margin of Safety (individual) | 103-135 | Adequate (≥100) |
| MoS (aggregate with 10% spray) | 92 | Below threshold |
| Genotoxicity | Negative (all tests) | Not genotoxic |
| Carcinogenicity studies | None available | Data gap |
| Benzophenone degradation | Increases over shelf life | Concern |
| Endocrine disruption | Evidence inconclusive | Under review |
| Sensitization rate | 0.7% (patch test study) | Rare |
The Bottom Line
Octocrylene is in regulatory limbo.
- In the US: NOT GRASE. FDA requires additional carcinogenicity and developmental/reproductive studies.
- In the EU: Currently permitted at 9-10%, but facing a potential ban at 0.001% for environmental reasons.
- The unique concern: It degrades into a possibly carcinogenic compound, and the concentration increases the longer your sunscreen sits on the shelf.
- For consumers: If you want to avoid octocrylene, look for mineral sunscreens (zinc oxide, titanium dioxide) or newer organic filters like Tinosorb S (bemotrizinol).
The octocrylene story is unusual because the primary ingredient might be safe enough, but its degradation product is the concern. It's a reminder that cosmetic safety isn't just about what goes into the bottle—it's about what happens to those ingredients over time.
References
- SCCS (2021). Opinion on Octocrylene. SCCS/1627/21. European Commission.
- Matta MK, et al. (2019). Effect of Sunscreen Application Under Maximal Use Conditions on Plasma Concentration of Sunscreen Active Ingredients. JAMA. DOI: 10.1001/jama.2019.5586
- Matta MK, et al. (2020). Effect of Sunscreen Application on Plasma Concentration of Sunscreen Active Ingredients. JAMA. DOI: 10.1001/jama.2019.20747
- Downs CA, et al. (2021). Benzophenone Accumulates over Time from the Degradation of Octocrylene in Commercial Sunscreen Products. Chemical Research in Toxicology. DOI: 10.1021/acs.chemrestox.0c00461
- de Groot AC, Roberts DW. (2014). Contact and photocontact allergy to octocrylene: a review. Contact Dermatitis. DOI: 10.1111/cod.12205
- Commission Regulation (EU) 2022/1176. Official Journal of the European Union.
- ECHA (2025). Annex XV Restriction Report: Proposal to restrict Octocrylene.
- FDA (2019). Proposed Administrative Order: Amending OTC Monograph M020 (Sunscreen Drug Products).
Shahar Benda
Cosmetic formulator and founder of Roots by Benda. Building the most comprehensive free ingredient database on the web.
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