Consultation on a proposed exposure model for assessing the safety of sunscreen ingredients in Australia

In July 2024, the TGA undertook a public consultation on establishing a model that more accurately estimates how much sunscreen Australians are exposed to on a regular basis. The model was proposed to enable the TGA to calculate the safe concentration of ingredients in sunscreens based on Australian conditions and the latest scientific information.

The consultation included 3 proposed options:

Option 1: Australian Sunscreen Exposure Model (ASEM)

Option 2: Scientific Committee on Consumer Safety (SCCS) exposure model

Option 3: Status quo

A total of 28 submissions were received from the therapeutic goods and cosmetic industry (industry organisations, sponsors, and manufacturers), non-profit organisations, universities, government organisations, health professional organisations, and individuals.

Submissions that consented to being published are available through the ‘View submitted responses’ link below. 

The TGA would like to thank all respondents for their submissions and extend our appreciation for the feedback received. Key points have been summarised below.

Preferred option

There was broad in-principle support for the adoption of the ASEM (option 1) for estimating sunscreen exposure when conducting sunscreen ingredient risk assessments. All respondents did not support Option 3 as the preferred option, and only 3 respondents (primarily European cosmetic industry associations) preferred Option 2. Some industry respondents did not endorse all the elements of the ASEM proposal and recommended suggestions for technical changes to utilise the ASEM more flexibly and reduce elements of the exposure calculations..

Importance of consistency of regulatory assessments and outcomes

Industry respondents emphasized the need for innovators and manufacturers of sunscreen ingredients to have confidence that the data they generate is consistent across all sunscreen regulators. One response highlighted that the calculations and assumptions for the ASEM formula require the same safety data inputs as the SCCS exposure model. This consistency supports innovators of new ingredients by allowing them to provide data that meets the requirements of different agencies.

Some respondents also commented on the Margin of Safety (MOS) calculations presented for the ASEM, noting that it generally produces congruent results, which increases confidence in their reliability. In contrast, they pointed out that the way dermal absorption data is presented can significantly affect the MOS calculations (up to 5-fold) in the SCCS exposure model.

The TGA notes that the ASEM, and the highest estimated exposure value, provides the greatest regulatory consistency for risk assessments compared to the other options proposed in the consultation paper. This consistency can better support innovation and development of sunscreen ingredients. However, the ASEM can be capable of being flexible, accommodating for different product types if required which was also identified as important by some respondents.

Flexibility of risk assessments using the ASEM

Multiple industry respondents recommended that flexibility should be available when utilising the ASEM in the safety assessment of sunscreens designed for specific product types such, such as facial sunscreens, which are used primarily for the face unlike general primary sunscreens. One respondent noted the use of these products is consistent with Scenario 1 (indoor worker) presented in the consultation paper, and these products are packaged in smaller volumes.

The TGA acknowledges the merit in utilising the ASEM tool to consider a usage scenario for sunscreens that are not intended for general use. Further consideration will be given to establishing a standardised exposure assumptions to be included in future guidance, and what risk management and presentation requirements may be needed to ensure such products are used as intended.

Sunscreen application rate of 2 mg/cm² used in the ASEM

The majority of respondents agreed with the calculations and assumptions used in the ASEM formula, which includes the application rate of 2 mg/cm² that is required to achieve the labelled SPF rating.

Some industry respondents suggested that the 2 mg/cm² application rate does not reflect real-world consumer behaviour, highlighting that consumers typically apply sunscreen at lower rates. Two of these respondents recommended 1 mg/cm² be used as the application rate. These respondents quoted five studies, including 3 Australian studies already discussed in the consultation paper, and 2 older European studies (conducted outside Australia), highlighting the median or mean application were less than 2 mg/cm².

The consultation paper emphasized that one of the guiding principles was to ensure the adopted model accounts for correct usage directions for effective sun protection and this will not be achieved with application rates less than 2 mg/cm². Moreover, the ASEM assumptions were constructed to reflect the higher end of sunscreen usage in Australia, rather than the average Australian’s usage. This approach was taken to ensure that the risk assessments for sunscreen ingredients, when based on the highest usage scenarios, will also guarantee safety for lower usage cases where less of the ingredient may be applied to the skin.

The TGA acknowledges that not all consumers apply sunscreen at the thickness to achieve the labelled SPF; however, the same Australian studies quoted, and discussed in the consultation paper, support that there are Australians that would apply at 2 mg/cm² or more. The European studies quoted are conducted outside of Australia, and may not reflect the unique conditions and practices in Australia today for the reasons described in depth in the consultation paper. An application rate of 2mg/cm² is needed to cater for Australians who use sunscreen at the application rate of 2mg/cm² and those that use less, to ensure that sunscreen ingredients are both safe and effective when used as directed.

Clarification of sunscreen exposure calculations for the ‘highest estimated daily exposure’

One respondent supported the ASEM if the TGA seeks to calculate the upper band of annual average daily sunscreen exposure in the Australian population, noting the ASEM offers a plausible and defensible measure, based on current evidence. However, this respondent disagreed that the ASEM calculates the maximum dose of sunscreen that could be applied in one day, as it averages exposure over the course of a year based on weekly patterns, underestimating the potential maximum exposure in a single day.

The TGA wishes to clarify that the ASEM calculates the upper band of annual average daily sunscreen exposure in the Australian population, based on current Australian evidence and guidelines. Risk assessments for sunscreen ingredients typically focus on long-term exposure, however, any acute toxicity concerns are still considered in the risk assessment, and this would still utilise the maximum expected dose that could be applied in one day for a sunscreen used for whole-body application (140 mL).

Some Australians may use more sunscreen than proposed in some scenarios

One respondent recommended that the TGA increase the duration from 26 days to 52 days for Scenario 6 to account for the lifestyle of residents in beach-side communities in northern Australia. Another respondent noted that in high-performance sports, there is often a deliberate strategy of training during the hottest part of the day, when UV exposure is likely to be high. Further, the culture regarding the use or non-use of sun-smart clothing varies between different sports. For example, some sports, such as beach volleyball and canoeing or rowing, involve a high degree of UV exposure with minimal sun-smart clothing.

The highest average daily sunscreen exposures as established by the ASEM is 673 mg/kg bw/day or 336 cm²/kg bw/day which broadly covers the majority of different scenarios and populations. As an example, if the duration for Scenario 6 is extended from 26 days to 52 days as suggested, the highest average daily sunscreen exposure for adults across a year (i.e. Scenario 4 + 6) would be 408 mg/kg bw/day or 204 cm²/kg bw/day, which is still less than 673 mg/kg bw/day or 336 cm²/kg bw/day. As such, the 673 mg/kg bw/day or 336 cm²/kg bw/day exposure values would still ensure safety of ingredients for these circumstances.

Exposure assumptions for toddlers

Some industry respondents supported the ASEM scenarios but had concerns about the assumptions made in establishing the highest estimated average daily sunscreen exposure for toddlers aged 1-2 in Scenarios 3. These respondents suggested that toddlers would not have enough sun exposure requiring 3 applications of sunscreen a day (as per Scenario 3) due to typical daily schedules that include naps, eating, baths and indoor play. Instead, they suggested 1-2 applications of sunscreen daily were more realistic.

As discussed in the consultation paper, 3 sunscreen applications per day for Scenario 3 was derived from Australian research reporting on actual sunscreen practices followed by 1,189 Australian SunSmart early childhood centres, surveyed in the 2018 National Early Childhood Sun Protection Policy and Practice Survey. It should also be noted that the study revealed a proportion of services (ranging from 4-20% across Australia) also applied sunscreens 4 times a day, however this frequency was not utilised in Scenario 3 as it would likely result in an overestimation of majority practice. The calculations used in the ASEM were based on empirical evidence rather than assumptions relating to periods of daily sun exposure or generalised routines. Additionally, sunscreen application frequency does not necessarily correlate with total time exposed to the sun i.e. smaller individual time periods of sun exposure when the UV index is 3 or above (which can be year-round in parts of Australia) may necessitate multiple sunscreen applications for each period of sun exposure.

Some respondents expressed concerns about the assumptions made in establishing the highest estimated average daily sunscreen exposure in Scenario 5, suggesting that one day a weekend may not sufficiently reflect the highest use case and that sun protective clothing portrays recommended behaviour rather than what may be observed. The TGA appreciates that the perception, or reality, may differ from the assumptions of the ASEM scenarios, as they are also designed to account for Australian recommendations and public health messaging rather than solely habits and practices. This provides a standardised approach to ensure regulatory certainty. The currently proposed highest estimated average daily sunscreen exposure is based on a high use situation in toddlers (annually) which provides a conservative estimate that is sufficient to cover for variability in sunscreen use among different population groups. The TGA observes that even slight modifications to Scenario 5 would not have a significant impact on the overall exposure values, as Scenario 3 (which already accounts for short clothing and 3 application per day across 240 days) constitutes the predominant exposure for toddlers annually.

Considering the reasons above, and that the majority of respondents agreed with the highest estimated average daily sunscreen exposure calculations, ASEM assumptions and ASEM scenarios, the TGA has maintained the overall exposure estimates for the Scenarios.

Flexibility of the ASEM compared with the SCCS

One respondent commented that the ASEM is a good model with clear rational and accurately reflects consumer use of sunscreens. However, they preferred the SCCS model (Option 2), suggesting it is more flexible than the ASEM. They assumed the ASEM would be legislated and could not be updated if scientific information changes, potentially making the methods used obsolete, unlike the SCCS model, which is provided as guidance.

The TGA wishes to clarify that, as stated in the consultation paper, the exposure calculations derived from the ASEM will be included in the Australian Regulatory Guidelines for Sunscreens not legislation. The ASEM can also be flexible to accommodate for new usage scenario (as described above for facial sunscreen products).

Weather assumption used in ASEM scenarios

Four respondents recommended that the TGA consider extreme and/or above-average temperatures when estimating the days sunscreens are being used in Scenarios 5 and 6. These respondents noted that most outdoor activity occurs during the winter months in northern Australia, while acknowledging the ASEM calculations may not change.

While the exposure calculations were calculated for one day each weekend over a 6-month period from October to April, a similar time period may be considered for other regions in winter months due to less extreme weather. As noted, this amendment would not alter the ASEM calculations.

Barriers to trade

Some industry respondents raised concerns that Australian-specific assessments could create trade barriers for European products. Different allowable concentrations in various countries may impact the supply of certain ingredients. These respondents emphasised the need to ensure a sufficient range of sunscreen active ingredients to formulate very high SPF products without compromising safety.

The consultation paper highlighted the differences between Australian environmental and cultural conditions and the regulatory framework for sunscreens compared to Europe. It stressed the importance of having an assessment process tailored to Australia's needs. Given that Australia has the highest incidence of skin cancer in the world, sunscreens designed primarily for UV protection are regulated as therapeutic goods with different compliance standards, unlike some sunscreens overseas that may be regulated as cosmetics. These differences can affect conclusions about the safety of ingredients, including approval of higher permitted concentrations in Australia compared to other countries. In contrast, alignment of international assessments may sometimes result in reduced availability of safe sunscreen ingredients in Australia. To ensure safe sunscreen active ingredients are not restricted from being used in Australian products, the TGA makes regulatory decisions following a careful analysis of the latest scientific evidence, tailored to Australia's distinct environmental conditions, health requirements, and regulatory framework.

Clarity on preferred method used when dermal absorption is reported as both proportion (%) and absolute amount (µg/cm²⁾.

Several respondents sought clarification on which method of the ASEM will be used when dermal absorption data is provided as both a % and µg/cm². These respondents emphasised the need for clear rules to determine which method will be used.

The choice of dermal absorption factor and method of calculation (i.e. Method 1 vs Method 2) depends on the type and quality of the data available for establishing the dermal absorption potential of the ingredient under consideration. In general, there is no preference for use of Method 1 or Method 2 as the ASEM approach results in the same risk quantification (i.e. same MoS values) irrespective of whether dermal absorption is quantified in μg/cm² (Method 2) or as a percentage (Method 1) when the test formulation is applied at a thickness of 2 mg/cm² in the dermal absorption study (compliant with OECD 428 – Guideline for Skin Absorption: in vitro method).

Dermal absorption studies (compliant with OECD 428) typically express results as both an absolute amount (i.e. µg/cm²) and a relative amount (percentage) and stipulate an application rate of 1-5 mg/cm² to mimic realistic human exposure. While 2 mg/cm² is the thickness of applied sunscreen needed to achieve the labelled SPF rating, studies often apply the test formulation at 3, 4, or 5 mg/cm² instead. The SCCS notes for guidance for testing of cosmetic ingredients (12^th Rev) also state that in vitro measurements using less than 2 mg/cm² are not technically feasible. The SCCS guidance on basic criteria for the in vitro assessment of dermal absorption recommends a 2-5 mg/cm² dose of test formulation. This can cause variability in the risk quantification (i.e. MoS calculation) between Method 1 and 2 since the reported absolute amount absorbed will be a different percent of 3, 4, or 5 mg/cm² application rate versus that of a 2 mg/cm² application (as highlighted in Attachment 3 of the consultation paper).

Where an application rate greater than 2 mg/cm² is used in the dermal absorption study, the absolute amount (µg/cm²) may be used when calculating the systemic exposure for risk assessments in order to minimise this variability. This is particularly important since it is known that the efficiency of absorption may remain the same or change as the concentration on the skin increases for some chemicals. For chemicals that penetrate the skin rapidly, the total amount of chemical absorbed increases as the dosage increases. Conversely, for chemicals that penetrate very slowly, the rate of penetration and the surface area exposed will have a greater influence on the systemic absorption dose than the extent of dermal deposition.

Since the efficacy of sunscreen ingredients relies predominantly on their ability to persist on the skin (including the top layers of the skin), they are likely to penetrate very slowly (or ideally not penetrate). Suggesting that the total amount of chemical systemically absorbed may not be proportional to the dermal dose/deposition. Hence using the dermal absorption factor expressed as a proportion (i.e. %) may not be appropriate for some sunscreen ingredients. 

Clarity on use of annual average instead of lifetime average for daily dose calculations

Some respondents queried why an annual average daily dose was calculated instead of a lifetime average daily dose in the ASEM. These respondents did not express a preference for either calculation method. Estimating sunscreen use is highly complex, as sunscreen use patterns vary among individuals based on several factors as discussed in detail in the consultation paper. A yearly model was utilised to account for the variability across weekday and weekend activity, and annual weather conditions. It is important to note, that while the ASEM calculates average daily exposure based on an annual sunscreen use pattern, this still allows for risk assessments that ensure safety of long-term sunscreen use throughout life.

We have considered all of the submissions and diverse stakeholder views, and in response, the TGA will adopt the ASEM and the highest estimated average daily sunscreen exposure values (Option 1). This will be utilised for assessments for ingredients in general sunscreens that can be used for the whole body and different ages. However, to address stakeholder feedback to increase flexibility, the ASEM tool will be utilised to allow future risk assessments to consider different product types such as face-only sunscreens. The Australian Regulatory Guidelines for Sunscreens will be updated accordingly, with guidance for future new sunscreen ingredient applications.

The ASEM significantly enhances Australia's ability to conduct safety reviews of sunscreen ingredients. We are now using it to finalise a literature review of some common sunscreen active ingredients, following international developments that have led to legislative changes for ingredients that can absorb into the body. Additionally, setting an acceptable regulatory limit for benzophenone (a degradant in sunscreens containing octocrylene) was deferred in December 2023, pending consideration of an appropriate sunscreen exposure model. The ASEM will now be utilised in assessing the risk of these active ingredients and benzophenone. Our review will consider the latest scientific evidence and use the ASEM to ensure these ingredients are safe for use at permitted concentrations. After completing our review, we will take any necessary regulatory measures and undertake public consultation as per TGA’s standard processes.