Sunscreens 2000 -- What You Need To Know

The synthesis of Vitamin D by the body occurs in the skin and requires UV radiation from the sun striking the skin to catalyze the reaction.   Thus, sunscreens can impair the synthesis of vitamin D which may require dietary vitamin D supplementation to provide a sufficient supply.  For most people this is not a problem, but in people who stay primarily indoors and apply sunscreen prior to going outdoors, even for short periods, there is the potential for impaired Vitamin D production, which can decrease the aborption of calcium from the intestine.   Insufficient calcium may result in rickets in children or osteoporosis in susceptible elderly.  But hypocalcemia could happen to anybody who dresses in a manner that most of their skin is protected from sunshine and in anybody who uses high SPF value sunscreen on exposed areas of skin over a prolonged period of time.  A physician should be consulted prior to taking any Vitamin D supplementation beyond dairy products or normal daily multivitamins that meet the FDA approved RDA requirements.   Dietary supplementation with calcium products containing vitamin D, such as calcium carbonate with vitamin D or oyster shell calcium with vitamin D, should first be discussed with a physician to assess whether such supplementation is necessary.
 

Levels of Protection

Per regulation 352.50, subpart C, as published in the Federal Register, Volume 64, Number 98, May 21, 1999, "Any statement accompanying the marketed product that states a specific SPF value above 30 or similar language indicating a person can stay in the sun more than 30 times longer without sunscreen will cause the product to be misbranded under section 502 of the Federal Food, Drug, and Cosmetic Act."  Products with such statements may not be marketed.  For example, a product labeled as SPF 45 would no longer be legal to market.  However, products using FDA approved sunscreen ingredients may state on their labels that they help prevent sunburn and that higher SPF values provide more sun protection.  Products with SPF values higher than 30 may only state "30 plus" or "30+" as their SPF values.

Additional product labeling now requires warning statements like: "Keep out of eyes," "Stop use if skin rash occurs," and "Keep out of reach of children."  Lipstick with sunscreen may now only warn that the user should "Stop use if skin rash occurs" or all three warnings if the manufacturer desires.

Sun Protection Factor

Sun Protection Factor or SPF as it is known describes the level of protection provided by the product.  It allows for easy comparison between products and allows the user to easily select a product with the sun protection they desire to help prevent sunburn, while allowing a natural tan to develop if desired.   The SPF value is the ratio of the minimal erythemal dose (MED) of protected skin to the minimal erythemal dose of unprotected skin in test subjects with Type I, II, and III skin (as below) exposed to a controlled artificial sun environment.  Assuming the sun intensity does not change throughout the day, a product with an SPF of 10 would allow a person to stay in the sun up to 10 times longer than they could without the sunscreen, as long as reapplication is done periodically, before they will receive the same amount of UV radiation as unprotected skin.  Unfortunately, it may take up to 12 - 24 hours to know whether a sunburn occurred.  And as mentioned previously, a sunburn has fully matured by 24 hours after the exposure.  An SPF 8 product on a certain person, for example, may be sufficient protection in the early to mid-morning, but may be insufficient protection between 10 am and 2 pm.  Therefore, a product with a higher SPF value may be needed initially or as the day progresses.

In order for people to select the proper sunscreens, the FDA has categorized skin into six types:

People with skin type I, II, or III will require a higher SPF value product than people with type IV, V, or VI for sufficient sun protection.

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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.