Sunscreens 2000 -- What You Need To Know

 FDA Approved Sunscreen Active Ingredients

The following figure shows the UV protective absorption spectrums of the FDA approved sunscreen active ingredients.  Combinations of these ingredients at various concentrations provide the desired SPF protection and UV spectrum of each sunscreen product, which along with cosmetic bases and other inert ingredients provide the water stability and final form of the product.

       Adapted from Federal Register 43, 38206 - 38269, 1978 and manufacturers product information.

Note: Micronized forms of titanium dioxide and zinc oxide do not block the entire range of ultraviolet radiation up to 700 nm.  In their previous opaque formulations, they were considered opaque sun blockers that scattered light from 200 nm to 700 nm, but in their new transparent micronized forms, they are considered to absorb UV radiation and have a much narrower spectrum limited to mid-UV-C, UV-B, and UV-A.  Micronized zinc oxide has a wider UV spectrum than micronized titanium dioxide.  Depending on the manufacturer, micronized zinc oxide can absorb UV-A radiation up to 380 nm or 400 nm.  Likewise, the UV absorption of micronized or microfine titanium dioxide extends to 350 nm or 370 nm depending on the manufacturer.   Neither zinc oxide nor titanium dioxide are absorbed by intact skin.

As can be seen in the figure, Avobenzone (Parsol 1789) combined with micronized zinc oxide offers the widest UV spectrum covering from UV-C through UV-A to 400 nm.  However, such a combination is no longer permitted by the FDA in any new products and would be deemed misbranded and subject to seizure.  Even though the combination was promoted in a June 2000 news report on KABC TV in Los Angeles, it would only pertain to currently marketed products, and those must be reformulated to eliminate the combination prior to May 2001 or face being deemed misbranded.  In fact, Avobenzone may not be combined with aminobenzoic acid (PABA), Padimate O, phenylbenzimidazole sulfonic acid, titanium dioxide, or zinc oxide in any preparation.   Combining cinoxate or oxybenzone with avobenzone would provide coverage for UV-B and the upper range of UV-C and would be FDA approved combinations.  Such a combination would afford ideal protection from UV-B and UV-A, providing the SPF value of the product is at least 15.  A product with such a combination of ingredients with an SPF value of at least 15 may not allow much of a tan to form in a single visit to the beach, which may be ideal for beach volleyball players who prefer a slow deep tan.   Likewise, a product with a combination of sulisobenzone and cinoxate would provide complete coverage for UV-B and partial coverage for UV-A up to 375 nm, which would allow a tan to form at a faster rate, while still offering sunburn protection.  However, sulisobenzone is easily removed by swimming, so such a product would not be water resistant or offer full protection after swimming.  The FDA panel recommends that sunscreen be reapplied after swimming to maintain protection.  Use the figure as an aid in selecting and comparing sunscreen products that will protect you from harmful UV-B radiation and some or all UV-A radiation.

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Copyright 2000 Solumedia and Douglas Barcon, Pharm.D.   All rights reserved.  This information and graphics may not be published, duplicated, or transmitted in any manner without the express written permission of Solumedia and the author.

This page was last updated on 04/29/05.