FAQ (Frequently Asked Questions)
Q. What are the 7 Signs of ageing and how do I test for them?
Set out below are our suggestions for measurement of improvement using you product.Typically, these studies need to run in the Winter months and for 60 to 90 days.
|Seven Signs of Ageing Study|
|Dark spots – hyper pigmentation||Colour Computer L*a*b* values||Minolta Hand held Spectrophotometer|
|Sagging skin. …||Elasticity||Cutometer|
|Dull glow-less skin. …||Skin gloss||Glossimeter|
|Lines & wrinkles. …||Surface Profiling||Surftest Profilometer|
|Dry skin. …||Skin Conductivity||Corneometer|
|Patchy skin. …||Skin Evenness||Mexameter|
|Open pores||Pore size measurement microphotography||Visioscan|
Q. What is an SPF?
Each person used in the SPF test has their individual UV light exposure time to develop an erythemal response without any protection – their Minimal Erythemal Dose “MEDi” . This will typically vary from 8 minutes up to 20 minutes in noon-day summer sun in Australia. We determine this expected MEDi as based on the instrumental measurement of the untanned skin colour . This is known as the ITAo – see column 4 of your ISO format full report. Each then has a differing number of second to reach the MEDi (unprotected) and SPFi (column 14). The ASPF is then the simple division of the seconds or UV light dose to reach the erythema with protection divided by the second or UV light dose for unprotected. In the 10 subject test, we use a mix of skin types, as required by the standard.
Q. What is an MED?
MED stands for Minimal Erythemal Dose. The Dose is the Minimum of accumulated (over time) amount of Erythemally (skin reddening) effective energy which is reported in the SPF test for each volunteer after visual examination of thier skin response. As we use a solar simulator which has a higher intensity of UV light than the sun, this time is typically seconds as compared with minutes in the sun.
Q. How do I test my COLOUR COSMETIC Sunscreen?
Previous advice from NICNAS in regard to testing of a range with colour variants indicates that the number of test subjects used to determine the mean SPF of a product should not be less than 10. It would be better to have equal numbers for all test groups. Hence we would suggest that a total of 12 subjects be used …
4 of the lightest shade, 4 of a middle shade and 4 of the darkest shade. In many ces, the SPF cnbeshown to vary by less that 2 units between mid and lightest and mid and darkest, which his acceptable to NICNAS.
NICNAS guidelines state “If more than two test subjects return SPFs for the test product which vary by >25% of the mean SPF in the test series, a new sample should be obtained”. There is always the chance that this approach will fail but in this case highly unlikely unless the colours have sun protection ability – for example Zinc Oxide which is often used as a “white” component in colours
Our standard charge for a 3 subject Preliminary Test applies ( one subject each colour) then the 12 Subject study total cost will be12/10ths of our costs as shown in the price list.
This arrangement is valid for Australia, but we also provide a composite 12 subject ISO 24444 – E.U. format reprot from the same test data.
Q. What are OUT OF RANGE SPF results?
A. Out of range results occur when the series of 5 exposures either does not produce an erythema for the test sample (greater than) or when all five spots show an erthyema (less than). As you nominated an SPF expected range of XXX to YYY, we set the 3rd (middle) exposure to this, then the range of exposures is plus/minus approximately 12% increments of this.
We are not dealing with a scientific instrument – we are using human test volunteers, so we have to be very cautious if we do not have any prior history of similar formulas.
Until we run the first one or two samples, we cannot know where the real target might be. The client pays for these test results, as they are beyond our control as the client normally instructs us on where to start. As these are greater than values, if you instruct us, we can add them into the valid results to include in the mean, but this may impact on the variability and confidence interval when we complete the study to 10 subjects.
There are various ways that a formulator can estimate expected SPF range, including on line resource. However, estimation of expected SPF from in silico or in vitro is not very reliable – otherwise there would be no need to test in vivo.
If we receive a sample and client estimated say SPF 80, we exposed the skin at that target, and it turned out to be SPF 10, then we would have a serious skin damage issue to deal with – and this responsibility transfers to the client. If the client under estimates the SPF, then, as the erythema develops in only 16 to 24 hrs, the test protocols do not allow us to run an infinite number of exposures. We have to work steadily and within a given range. Each time we test, we have to pay our subject. If they are here longer due to higher exposures, then we have to pay them more and it takes up longer clinical time – hence the pricing schedule. If we have to reject a result because it is out of range, then we have to replace it. This is why we need to charge for more than 10 subjects if this is the case.
The same situation arises when we run water resistance testing- if the product washes of, then SPF can end up being close to zero!
Q. How can I claim “REEF SAFE” for my sunscreen product?
There is no agreed or regulated requirement to qualify “Reef Safe”.
There are really 2 options…
- Water resistance test to 4 hrs – both in vitro and in vivo. “If it doesn’t wash off, then why should it be a concern?”
- Suite of marine environment toxicity tests…
- Microalgae Cell Division
- Sea Urchin Larval Development
- Fish Larvae Development.
Your product can be tested in a Eurofins lab – please request a protocol.
Q. Do I have to retest my Sunscreen if I make minor changes to the formula?
TGA guidance for similar formulas can be found on the following link…
In effect, if the change is acceptable within the same AUST L listing,(although you may not actually be applying this via TGA), then retesting of SPF should not be required. However, clients often run a preliminary (3 subject) test to verify and for supporting evidence.
Q. My product passed the FDA Broad Spectrum test – will it pass ISO 24443?
The simple answer is that a US formulated product, where content of UVA actives are bound by FDA, will have difficulty in complying with requirements for a one third UVAPF ratio when tested by the ISO 24443 method.
For the ISO 24443 in vitro UVAPF test, the in vivo SPF, along with the raw in vitro absorbance data, Erythemal Action Spectrum and the PPD action spectrum is used to calculate the UVAPF (UVA Protection Factor). This UVAPF (post exposure) divided by the label SPF needs to be at least 0.333.
For example, in order to claim SPF 30, the UVAPF needs to be at least 10. A higher in vivo SPF results in a higher UVAPF. In order to pass the ratio, the Critical Wavelength also needs to be above 370 nm.
For FDA, although the ISO equivalent, the previous COLIPA method is used for measurement, FDA only require the Critical Wavelength to be above 370 nm. There is no ratio required. Additionally, the pre-irradiation step to challenge for photo stability is not as aggressive, therefore, it is not unusual for a product to pass FDA but fail ISO.
We recommend that you first test to ISO 24443. As well as covering requirements for around 60 countries, our report will give indicative passes for other UVA protocols (no extra charge).