Dioxybenzone Safety: Rarely Used, Barely Measured

Is Dioxybenzone Safe? The Short Answer

There is no finding of harm, and there is also nothing solid to reassure you with. The FDA proposed Category III for dioxybenzone in its 2019 review — "The public record does not contain sufficient data to support a positive GRASE determination for … dioxybenzone … at this time" — and the 2021 proposed order that replaced that rulemaking proposes requirements "substantively the same" as the 2019 rule, with scientific discussions that "are generally the same." Neither has been finalized.

Dioxybenzone's file is thinner than most. Of the ten filters with the biggest gaps, the FDA said only homosalate, octinoxate and octisalate "appear to have been evaluated in human absorption studies"; dioxybenzone was not among the three, and none of the ten had been through an adequate maximal-usage trial. When the agency later offered to defer decisions for ingredients whose makers were generating the missing data, it received a request covering eight filters. Dioxybenzone was not one of them.

The reasonable worry is guilt by chemistry rather than by evidence. Benzophenone-8 differs from oxybenzone — benzophenone-3, the filter with the highest measured systemic absorption of any tested — by a single hydroxyl group. That similarity is a reason to want the data, not a measurement in itself, and it is worth being precise about what follows from it: bans written against oxybenzone, such as Hawaii's, do not name dioxybenzone.

Practically, this is an easy ingredient to avoid. Dioxybenzone appears in very few current products, and nothing about its performance is hard to replace.

Chemical Properties and UV Protection

Dioxybenzone is a dihydroxy benzophenone derivative approved at up to 3% concentration in the US. It belongs to the same chemical family as oxybenzone but with additional hydroxyl groups that slightly modify its properties.

UV Absorption Profile

Protection characteristics:

• Absorbs across UVB and into the shorter UVA (UVA II) range
• Broader spectrum than oxybenzone
• Still requires additional filters for complete coverage

Structural Relationship to Oxybenzone

As benzophenone-8, dioxybenzone shares core structure with oxybenzone (benzophenone-3):

• Same benzophenone backbone
• Additional hydroxyl groups
• Similar UV absorption mechanism
• Likely comparable biological activity

Structure-Activity Implications

Chemical similarity suggests dioxybenzone likely exhibits similar problematic properties to oxybenzone, including high systemic absorption, endocrine disruption potential, and environmental persistence.

Limited Research and Data Gaps

Critical missing information includes:

• No FDA absorption studies: Systemic exposure levels unknown
• No endocrine assessments: Hormonal effects unstudied
• Minimal allergy data: Sensitization potential unclear
• No environmental studies: Impact on coral reefs unknown
• Limited toxicology: Long-term safety unestablished

This lack of data is particularly concerning given that related benzophenones show significant adverse effects.

Potential Safety Concerns

Predicted Issues Based on Structure

Based on benzophenone class characteristics, dioxybenzone likely exhibits:

• High dermal absorption: Small molecular size enables skin penetration
• Endocrine activity: Benzophenones typically show hormonal effects
• Photoallergic potential: Common among benzophenone filters
• Environmental persistence: Stable structure resists degradation

Cross-Reactivity

Individuals allergic to oxybenzone may react to dioxybenzone due to structural similarity. This cross-sensitization risk further limits its utility.

Market Presence

Dioxybenzone usage is extremely rare:

• Virtually absent from US products
• Not approved in EU or most other regions
• Occasionally in older formulations
• Sometimes confused with oxybenzone in listings

Manufacturers avoid dioxybenzone due to:

1. Association with problematic oxybenzone
2. Lack of safety data
3. No advantages over other filters
4. Consumer awareness of benzophenone risks

Regulatory Status

United States: Approved at up to 3% concentration. FDA has not determined GRASE status and lacks data for safety assessment.

European Union: Not approved for cosmetic use.

Global status: Generally not approved internationally. Where permitted, rarely utilized.

Environmental Considerations

While unstudied specifically, dioxybenzone likely shares environmental concerns with oxybenzone:

• Potential coral reef toxicity
• Bioaccumulation in marine life
• Persistence in aquatic systems
• Endocrine disruption in fish

Given bans on oxybenzone for environmental reasons, dioxybenzone would likely face similar restrictions if more widely used.

Why It Remains Approved

Dioxybenzone's continued approval despite concerns reflects:

1. Grandfathered status: Pre-existing approval from less stringent era
2. Minimal use: Low priority for regulatory review
3. Data requirements: FDA needs studies that don't exist
4. Industry abandonment: No sponsor to fund required research

Recommendations

Given structural similarity to problematic oxybenzone and absence of safety data:

• Avoid dioxybenzone-containing products: Unnecessary risk with no unique benefits
• Choose studied alternatives: Many filters have comprehensive safety data
• Assume similar risks to oxybenzone: Prudent given chemical relationship
• Check ingredient lists carefully: May appear in older or imported products

Dioxybenzone represents the worst combination in sunscreen ingredients: likely safety concerns based on chemical structure but lacking data to confirm or refute risks. Its structural similarity to oxybenzone - now banned in multiple jurisdictions - suggests it would show similar problematic properties if studied. The absence of safety data is not evidence of safety, particularly for a benzophenone compound. Consumers should avoid this ingredient entirely given the availability of better-studied, safer alternatives.

Recommended: Raw Elements Face + Body SPF 30 — a dioxybenzone-free mineral alternative — non-nano zinc oxide