UV protection and sunscreens

Question 1

Which UV rays have the greatest destruction potential?

Answer 1

UV-A rays => penetrate deeply into skin

Question 2

What contributes most to photoaging?

Answer 2

UV-A

Question 3

What is the result of UV-B energy being directly absorbed by DNA?

Answer 3

formation of cyclobutane pyrimidine dimes and pyrimidine-pyrimidone photoproducts in DNA that block replication and transcription

Question 4

What is a common complaint of inorganic sunscreens?

Answer 4

thick consistency and clumping tendency

Question 5

What is SPF based on? so what does it chiefly measure

Answer 5

erythema=>UV-B exposure

Question 6

What does a broad spectrum UV-A protection cover?

Answer 6

greater than 370nm to measure breadth of absorbance by sunscreen

Question 7

What is substantivity?

Answer 7

sunscreen’s ability to remain effective under adverse conditions like water and sweat

Question 8

What are the recommendations to prevent UV damage?

Answer 8

minimal sun exposure during peak hrs; wearing clothing; broad spectrum sunscreen w/ UV-A protection

Question 9

What are the long term effects of UV light on skin? immediate effects?

Answer 9

long=> photoaging, immunosuppression, carcinogenicity;

immed=>erythema

Question 10

What are the 2 categories of sunscreens?

Answer 10

chemical and physical (inorganic)

Question 11

How is SPF measured?

Answer 11

amount of UV radiation required to produce a sunburn on protected skin relative to that of unprotected skin

Question 12

What is an important correlation b/w UV dosage and SPF?

Answer 12

UV radiation dosage depends on exposure duration and intensity while SPF is not related to duration of UV exposure

Question 13

Ability to block UV radiation depends on what?

Answer 13

critical wavelength measurements of UV-A absorbance in combination w/ SPF for complete UV protection

Question 14

Define a sunscreen’s stability

Answer 14

long lasting protection especially to prevent photodegradation