CIR sets 10% AHA safety limit based on sun sensitivity, skin irritation data.

CIR AHA SAFETY STAMP OF APPROVAL INCLUDES SUN PROTECTION PROVISO stating that products containing glycolic acid or lactic acid should be "formulated to avoid increasing the skin's sensitivity to sun" or should include a recommendation of "the daily use of sun protection" under the label's "directions for use." The Cosmetic Ingredient Review Expert Panel issued a tentative final report on the safety of the alpha hydroxy acid ingredients as used in retail products and in professional-use products at its Dec. 16-17 meeting.

The sun protection proviso proved to be the most contentious portion of CIR's AHA safety conclusion. The seven-member panel and CIR's nonvoting liaisons were split on both the meaning of the clause and its necessity in the safety assessment.

CIR's tentative safety report concludes that "glycolic and lactic acids, their common salts and their simple esters, are safe for use in cosmetic products at concentrations less than or equal to 10%, at final formulation pHs greater than or equal to 3.5, when formulated to avoid increasing skin's sensitivity to sun or when directions for use include the daily use of sun protection."

"When applied by trained professionals," CIR tentatively found AHAs safe at concentrations of 30% or less with a finished product pH 3 or greater "in products designed for brief, discontinuous use followed by thorough rinsing from the skin." The professional-use conclusion also requires "application accompanied by directions for the daily use of sun protection." Physician-use AHAs were excluded from the panel's finding.

CIR's tentative final decision on AHAs is subject to a 90-day public comment period, after which the Expert Panel will evaluate any additional data received and then issue a final report on the acids' safety. CIR has been working to reach a decision on AHA safety since 1994, when it gave the ingredient class a high priority on its review list due to the popularity of AHA products with consumers.

CIR based its AHA safety conclusion on a sunburn cell test sponsored by the Cosmetic, Toiletry and Fragrance Association, which demonstrated "slight but not significant increase in skin sensitivity from sunlight," CIR Team Leader Donald Belsito, MD, University of Kansas Medical Center, stated. The data also showed how AHA concentration and formulation pH impact skin irritation.

In previous meetings, CIR identified the effect of AHAs on skin barrier function, their irritation potential and whether they exacerbate sensitivity to sunlight as the parameters for assessing the ingredients' safety.

On the basis of the irritation data alone, CIR "probably would have given a higher percentage allowable [for glycolic acid], perhaps as high as 20%," Belsito noted.

"Our restriction really came about on the basis of the sunburn cell studies, because they were done at a highest concentration of 10%," Belsito explained. CTFA's sunburn cell test examined the effect of long-term (12 weeks) application of glycolic acid on the penetration of UV light through the stratum corneum.

With regard to irritation, CIR Team Leader Arnold Schroeter, MD, The Mayo Clinic, noted that AHA formulations "should...maintain effect but...reduce with all possibility the stinging and burning that occurs." He added that "protection from ocular irritation" also is a concern.

The panel's skin penetration concerns were allayed by FDA-supplied data "indicating that...AHAs do not enhance penetration [of other materials] through the skin," Belsito noted. The penetration data were "fairly clean," he added.

FDA's skin penetration studies also examined the absorption of AHAs through the skin; the agency found that 27.2% of glycolic acid (concentration of 5%, pH 3) was absorbed through human skin over a 24-hour period. Despite CIR's safety recommendation, Belsito characterized this absorption rate as "problematic" based on the "complete lack of any other toxicological data" available on AHAs.

The AHAs that fall into the class of "glycolic acid, lactic acid, their common salts and esters" as defined by the CIR report include glycolic acid; ammonium, calcium, potassium and sodium glycolate; methyl, ethyl, propyl and butyl glycolate; lactic acid; ammonium, calcium, potassium, sodium and tea lactate; methyl, ethyl, isopropyl and butyl lactate; and lauryl, myristyl and cetyl lactate.

FDA data on the glycolic acid family show that the ingredients were used in 90 product formulations in 1996, including 19 moisturizing preparations, 14 cleansing preparations, 11 "other" skin care preparations, eight face and neck preparations, and seven body and hand preparations. FDA data are compiled from formulations submitted under the agency's Voluntary Cosmetic Reporting Program.

Data supplied to the panel by CTFA show that current glycolic acid concentrations of use range from less than 1% in skin fresheners to 20% in some skin care preparations, with night products, face and neck products and body and hand products containing concentrations as high as 13%. Glycolic acid-containing moisturizing products on the market contain concentrations of 13% or less, according to CTFA.

Lactic acid and its common salts and esters were used in 782 cosmetic formulations reported to FDA in 1996. The ingredient grouping was most commonly used in lipsticks (94), moisturizing formulations (55), "other" skin care preparations (47), cleansing products (43) and body and hand preparations (40). CTFA data show that use concentrations for lactic acid range from .1% in hair preparations to up to 11.8% in face creams.