Sunscreens 2000 P5

Sunscreens 2000 -- What You Need To Know

Selection and Use of Sunscreens

Selection of the proper sunscreen product requires knowledge of the type of environment the person will be subjected to during the day. Somebody who will be sunbathing in Las Vegas on a hot summer day will require a different product than somebody sunbathing at Pismo Beach, where it is cooler and where there won’t likely be sweating. Likewise, somebody body surfing, swimming, or snorkeling will require a more water resistant product than somebody sunbathing and not swimming. The FDA has broken down the water resistance of products into two classes: Water resistant and very water resistant.

Water resistant sunscreen products must maintain their labeled SPF value after 40 minutes of water immersion described as 20 minutes of moderate water activity, followed by a 20 minute rest period without toweling, followed by 20 additional minutes of moderate activity in the water. Prior to the first period of water activity, a waiting period as described on the product label must be completed to allow the product to become fully active.

Very water resistant sunscreen products extend the process of water resistant products to 80 minutes, while maintaining their labeled SPF values. Testing of very water resistant products requires 20 minutes of moderate water activity, followed by a 20 minute rest period without toweling, then 20 additional minutes of moderate activity in the water, followed by another 20 minute rest period. Then the process is repeated, so that a total of 80 minutes is spent in the water. Prior to the initial period of water activity, a waiting period as described on the product label must be completed to allow the product to become fully active.

Products that comply with these guidelines can be labeled as "water resistant," "water/sweat resistant", or "water/perspiration resistant." Products that meet the criteria for very water resistant can use the terms "very water resistant," "very water/sweat resistant," or "very water/perspiration resistant."

In any case, unless a sunscreen is reapplied in sufficient amount (about 1 - 2 ounces for the whole body) during the day, its protective effects will be lost through skin absorption, perspiration, toweling, or washing off in the water. A good rule of thumb would be to liberally reapply sunscreens every 1 - 2 hours or more often, while exposed to the sun and while participating in water sports. The initial application should be applied per product labeling before going outdoors, to allow time for the sunscreen to bind to the skin and be partially absorbed for maximum performance. This waiting period is typically about 20 -30 minutes, but can be as long as 1 - 2 hours for products containing para aminobenzoic acid (PABA), its variants, and Padimate O. A product with an SPF value of 15 is ideal for most people and is the minimum recommended to protect against skin cancer, except those with Type I skin who should use a product with a higher SPF. But unless it is reapplied often, it’s protective value drops considerably.

Copyright 2000 Solumedia and Douglas Barcon, Pharm.D. All rights reserved. This information 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.