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Support Group for Sun Sensitive People
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Sunscreen Standards for UVA ProtectionThe sunscreen standards for UVA protection are very confusing. Each country seems to have its own sunscreen standard for UVA protection, and it is very difficult to understand what each sunscreen standard means. A sunscreen label might claim to have UVA protection, but because of lax or meaningless regulations, the sunscreen may provide very little UVA protection. The lax or meaningless UVA standards hurt both the people who need good UVA protection, and they hurt the sunscreen manufacturer who does make an excellent UVA protection product. For this reason, I am proclaiming the Persistent Pigment Darkening Method (PPD) method for measuring UVA protection as the gold standard by which all the other UVA standards are measured in this discussion. Sunscreens with high PPD ratings do the best to protect those of us with extreme sun sensitivities against UVA light. So assume we want sunscreens with UVA ratings with a PPD greater than 15. ( An estimate of the alternate UVA method's ability to measure a PPD greater than 15 is listed in Table 1. So sunscreens with a PPD rating, a UVA/UVB rating, or a Boots Star rating can provide UVA protection equivalent to a PPD of 15 or greater. Some UVA standards that cannot measure a PPD of 15 or greater include: Japanese PA+++ standard and Australian UVA standard, and the U.S. (no standard). Table 1: Can the alternate UVA measurement methods measure a PPD >
15?
Table 2: Experiments in changing UVA protection using the CIBA sunscreen simulator. [Chemistry Today]
There are now 4 countries/regions with an
official UVA standard:
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| PPD method | 2-4 | 4-8 | 8+ |
| Japanese PA method [Nora80] | PA+ | PA++ | PA+++ |
Another development started in the United Kingdom about 10 years ago. The sunscreen manufacturer and retailer Boots developed and enforced the Boots Star Rating System based on Diffey’s UVA/UVB ratio (11). The criterion for the recently introduced 5-star rating, given by a UVA/UVB ratio > 0.91, comes closest to uniform UV protection. calculation of a ratio of average UV absorbance to average UVB absorbance. The Boots Star Rating is a calculation of a ratio of average UV absorbance to average UVB absorbance. [Stanfield]
| UVA/UVB | 0 to 0.2 | 0.21 to 0.4 | 0.41 to 0.6 | 0.61 to 0.8 | 0.81 to 0.9 | >0.91 |
| Boots Stars | none | * | ** | *** | **** | ***** |
| Category | none | Minimum | Moderate | Good | Superior | Ultra |
The UV-A/UV-B ratio defines the performance of a sunscreen in the UV-A range (320 – 400
nm) in relation to its performance in the UV-B range (290 – 320 nm). It is calculated as the
ratio between the areas under the UV-A and
UV-B parts of the extinction curve, both areas are normalized to the range of wavelengths
involved. [Tinosorb] A UVA/UVB ratio goes from 0 to 1. The lower the ratio, the
worse the UVA protection. The closer the UV-A/UV-B ratio approaches 1, the
better the sunscreen will protect against UVA radiation. Assuming of course that
the sunscreen provides good UVB protection. You could have a sunscreen with a
low UVB rating that has a high UV-A/UV-B ratio which would mean you have a
sunscreen that protects equally as bad for UVB as it does for UVA.
The critical wavelength standard is difficult to understand. The higher the the critical wavelength of a sunscreen, the better its UVA-performance in relation to its UVB-performance. The critical wavelength is given as the upper limit of the spectral range from 290 nm on, within which 90% of the area under the extinction curve of the whole UV-range between 290 nm and 400 nm is covered. [Tinosorb] The Critical Wavelength method requires mathematical integration of the in vitro product absorbance spectrum from 290 to 400 nm to determine the wavelength below which 90 percent of the cumulative area of the absorbance curve resides. If that wavelength is 370 nm or greater, the product is considered "broad spectrum," which denotes balanced protection throughout the UVB and UVA ranges. [Stanfield]
That leaves FDA with an unresolved technical dilemma that it is trying to resolve through additional research. "We are trying to determine a testing method that will demonstrate that a sunscreen is providing UVA protection," Lipnicki says. A claim such as "broad spectrum" on a sunscreen label needs to be supported by evidence that the product provides significant and meaningful protection across the entire UVB/UVA spectrum.[FDA] Matthew Holman, interdisciplinary sciences team leader with the FDA, notes that the agency and the manufacturers simply have lacked sufficient understanding of how UVA works, how its effects can be measured and how products can be accurately tested and labeled for their effectiveness against UVA. For now, manufacturers are allowed to claim ''broad spectrum'' protection if their product provides any amount of UVA protection. [Huget]
The SPF number is derived from the time or dose required to produce a minimal
reddening of the skin, divided into the time or dose required to produce the
same degree of skin reddening with the product applied. [(APTF)]
[Tinosorb] Ciba Tinosorb S: The highly efficient broad-spectrum UV absorber Product brochure
[Chemistry Today] Emerging standards in UVA protection Household and Personal Care Today • Supplement to chimica oggi/Chemistry Today
[Nora80] (Estimated PPDs of sunscreens) http://www.makeupalley.com/user/notepad/nora80/
[Ciba] Ciba ® Sunscreen Simulator: Prediction of sun protection factor and UVA parameters http://www.cibasc.com/pf/docMDMS.asp?targetlibrary=CHBS_HP_MADS&docnumber=5295
[Stanfield] UVA Protection: An Update, Joe Stanfield, Suncare Research Laboratories, LLC, May, 2006
[FDA] Trying to Look SUNsational Complexity Persists In Using Sunscreens
FDA Consumer magazine
July-August 2000
[Huget] Most sunscreens only do half the job, Jennifer Huget, 07/24/05, Sun
Herald, Sun Herald - 072405
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Persistant Pigment Darkening
(PPD, UVA-PF)