Comprehensive review of avobenzone (butyl methoxydibenzoylmethane) toxicology data and human exposure assessment for personal care products
Bibliographic record
Abstract
A comprehensive review of existing toxicity and human exposure data for the ultraviolet filter avobenzone (butyl methoxydibenzoylmethane) was conducted to assess its safety as currently used in over-the-counter sunscreen formulations. Avobenzone has a suitable safety profile without any clear markers of toxicity or endpoints of concern. There are sufficient clinical studies and in vitro and in vivo toxicity studies in animal models to assess avobenzone’s pharmacokinetics, pharmacodynamics, and potential toxicological properties, supportive of its long history of safe use. No harmonized dermal absorption value was available, but the clinical data indicate low percutaneous absorption of avobenzone in humans (≤0.59% of the applied dose). There were no data to characterize the distribution of avobenzone; however, four tentative metabolites of avobenzone have been identified, and limited excretion in urine was demonstrated in human biomonitoring studies. Avobenzone generally did not cause dermal irritation or sensitization, but indications of photoallergy have been reported in clinical case studies. The acute toxicity profile indicated that avobenzone has minimal toxicity. The no-observed-adverse-effect level (NOAEL) for general toxicity from a rat dietary subchronic toxicity study was 450 mg/kg/day. There was no evidence of avobenzone effects on immune tissues or the estrogen, androgen, or thyroid systems. Although there were no formal 2-year carcinogenicity studies for avobenzone, a 90-day dietary exposure study in rats did not show any increase in hyperplasia of any tissue or evidence of cytotoxicity, and avobenzone has not shown any indication of genotoxicity either in vitro or in vivo. Together, this indicates that key events for modes of action for avobenzone are absent and carcinogenicity in humans is unlikely. Based on the selected rat subchronic NOAEL and conservative assumptions for estimating the systemic exposure dose (SED) from the application of sunscreen products, margins of exposure (defined as the ratio of NOAEL to SED) greater than 100 were obtained for avobenzone. Therefore, the available data show that avobenzone is unlikely to pose a risk to human health when used in sunscreen products at concentrations up to the permitted maximum usage levels in the United States and Canada, which is 3%.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.001 | 0.001 |
| Meta-epidemiology (narrow) | 0.001 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 0.001 |
| Bibliometrics | 0.005 | 0.003 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.001 | 0.001 |
| Open science | 0.001 | 0.001 |
| Research integrity | 0.001 | 0.001 |
| Insufficient payload (model declined to judge) | 0.005 | 0.001 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".