SPF (Sun Protection Factor) and the FDA
What is an SPF rating?
Sun Protection Factor (SPF) refers to the U.S. Food and Drug Administration's (FDA) approved techniques to assess the efficacy of a sunscreen in the Ultraviolet B (UVB - burning ray) portion of the spectrum.
An SPF rating dose not measure Ultraviolet A (UVA - againg ray) protection.
The textbook definition of SPF is the ratio of the time of ultraviolet radiation (UVR) exposure necessary to produce minimally detectable erythema (redness) in sunscreen-protected skin to that time required to produce the erythma in unprotected skin.
So, the SPF number gives you some idea how long you can stay in the sun without burning. For example, if you normally burn in 10 minutes without sunscreen and you've applied a liberal dose of a sunscreen with an SPF 15, you should be protected from sunburn for 150 minutes. This dose not mean that you are protected from other radiation damage. Abroad-Spectrum sunscreen is required to give protection in the UVA range as well.
A Very Water Resistant rating is given if that same sunscreen still tests at the same SPF after being applied to human subjects and submerged in moving water for four 20-minute immersions. Under the FDA monogragh, it is no longer permissible to claim a "Water Proof" rating.
What's the difference between a sunscreen and a sunblock?
Under the new FDA monograph the word "Sunblock" is no longer allowed. The FDA is trying to eliminate any confusion or any sense of false security the public may have. No sunscreen provides 100% protection.
Is there such a thing as a safe tan?
NO! A tan is a sigh of injury. It is the body's attempt to increase sun protection after the skin is already permanently damaged by an overdose of ultraviolet radiation! 80% of the visible signs of aging are due to sun exposure. And that means all sun exposure, because radiation is cumulatve. Walking to the mailbox, getting in your car and sitting by the window all count! Unprotected exposure to the sun is like sitting in a time machine on fast-forward.
Can sun damage be reversed?
We are told some of it can be if, and only if, the skin is always protected from the sun. The excellent skin care products on the market today can substantially aid the skin in reversing sun damage. But they do no good if they aren't combined with sun protection. Months of hard work can be undone in one morning working in the garden wearing no sunscreen, hat or gloves.
Beautiful Skin At Any Age
Meredith Bay Laser Center
169 Daniel Webster Highway
Meredith, NH 03253
(603)556-7271
