Safety review of seven active sunscreen ingredients

Executive summary

We conducted a safety review of 7 active ingredients in therapeutic sunscreens:

• butyl methoxydibenzoylmethane (also known as ‘avobenzone’)
• ethylhexyl triazone
• homosalate
• octocrylene
• octyl methoxycinnamate (also known as ‘octinoxate’)
• oxybenzone
• phenylbenzimidazole sulfonic acid.

This safety review was dependent on the national and international safety assessment reports and peer reviewed publications investigating the safety and toxicokinetics of the ingredients, where available. These ingredients were selected for priority review considering the status of the availability of nonclinical safety data to TGA and their reported use in higher number of sunscreen products marketed in Australia in addition to the safety signals reported overseas.

Based on available scientific data, the following active ingredients were considered to be low risk and appropriate for use in therapeutic sunscreens:

• butyl methoxydibenzoylmethane
• ethylhexyl triazone
• octocrylene
• octyl methoxycinnamate
• phenylbenzimidazole sulfonic acid.

However, based on the data considered in this safety review, the TGA recommends regulatory controls for homosalate and oxybenzone to restrict their permitted concentrations and use in therapeutic sunscreens.

The two main issues considered in this safety review were the evidence for the ability of these ingredients to penetrate the skin to reach viable cells systemically and the potential toxicity exerted by them.

Based on the data available for these ingredients, a Margin of Safety (MoS) was determined for each of the ingredients using the Australian Sunscreen Exposure Model (ASEM) which underwent public consultation in 2024. A MoS of 100 or more is considered to be satisfactory for controlling for the risks to human health and safety from long-term use of an ingredient by the Australian population. The MoS was calculated based on the current maximum permitted concentrations in therapeutic sunscreens (which are regulated as listed medicines).

However, it is important to note that the concentrations of these actives in products can be less than the maximum permitted amounts; and that some products contain a combination of the active ingredients.

The ASEM has been used to calculate the highest estimated average daily sunscreen exposure modelled to account for use of therapeutic sunscreens applied long-term to the face and body by children and adults. The MoS for butyl methoxydibenzoylmethane, ethylhexyl triazone, octocrylene, octyl methoxycinnamate and phenylbenzimidazole sulfonic acid were above 100. These ingredients are unlikely to cause any significant systemic toxicity and are therefore considered low risk when used in therapeutic sunscreens.

In the case of homosalate and oxybenzone, the MoS using the highest estimated sunscreen exposure for application of a general sunscreen to the body, at the maximum permitted concentration, was less than 100. Hence, the ASEM was utilised to estimate alternative exposures based on specific parts of the body e.g. head, face and/or hands. In this case, the MoS was more than 100 and considered low-risk for long-term use when limited to the face and hands at concentrations between 11.4% and 2.7% homosalate, and 9.8% to 10 % for oxybenzone, depending on the type of product and the directions for use (e.g. limited to face-only use).

The limitations of this review are:

1. The toxicological endpoints, (NOAELs), were collected from published international safety assessment reports and scientific literature. As full data sets, including all raw study data, were not available for independent corroboration of the findings from these reports and literature, this review was dependent on the veracity of the details provided in those reports and literature.
2. Additional studies would be required to fully evaluate the pharmacokinetics of the active ingredients.
3. The available information on butyl methoxydibenzoylmethane, homosalate, octocrylene, octyl methoxycinnamate and oxybenzone indicate potential endocrine effects, however, the data are not adequate to derive a conclusion as to their causality in humans. Further data on the endocrine modifying potential of these chemicals are warranted.
4. Consumer products other than sunscreens that contain the same active ingredients were not considered in this review.
5. The exposure to metabolites of these ingredients or impurities present in these ingredients has not been considered in this review.