SPF TESTING SERVICES
1. What Is SPF?
● SPF (sun protection factor) is basically defined as a measurement of the fraction of sunburn- producing ultraviolet radiations that come in contact with our skin.
● SPF is not considered to be a completely accurate measure of skin damage, since UV-A radiations are known to cause invisible skin deterioration and ageing.
2. Ultraviolet Radiation:
● Ultraviolet radiation is a type of electromagnetic radiation coming from the sun, with a wavelength ranging from 10 nm to 400 nm.
● UV-A rays have the least energy and usually cause some indirect damage to cellular DNA and lead to skin ageing, wrinkles over time. These rays are also known to cause a few types of skin cancer.
● UV-B rays cause direct damage to cellular DNA and are the main cause of sunburns. These rays are known to cause most types of skin cancers.
● UV-C rays are the rays having the highest energy, and thus, they interact with the ozone in the atmosphere. These rays do not make it to the ground.
3. Dangers Of Ultraviolet Radiation:
● UV-B radiations are mainly known to cause various kinds of skin cancers, basal cell carcinoma and squamous cell carcinoma.
● UV rays cause sunburn due to damage to skin cells. This damage increases blood flow to the affected area, and causes skin reddening, which is a characteristic feature of sunburns.
● UV radiations are said to suppress the immune system after continued exposure to radiation for a longer period of time.
● These radiations are also known to damage the tissues of the eye and cause a condition known as photodermatitis.
4. Sunscreen:
● Sunscreen is a photoprotective product meant to protect our skin from UV radiations by absorbing or reflecting sun’s UV radiations, to prevent sunburns and skin melanomas.
● Sunscreen is recommended by the American Cancer Association to reduce the risk of squamous cell carcinoma and melanomas.
5. SPF Testing Methods:
● The real degree of protection provided by the sunscreens is a cause of a lot of consumer confusion.
● This has caused many countries to introduce labelling restrictions and request justification of claims.
● The FDA has mandated a maximum limit to SPF labelling to be SPF 50+, due to lack of sufficient evidence to prove that sunscreens of higher rating provide more protection.
● A xenon arc lamp/ solar simulator is used to irradiate the skin of all the test subjects to test the protective capability of various sunscreens.
● The xenon arc lamp used in the test has a known and defined output.
● A test panel is put together, consisting of test subjects having completed a preliminary medical examination.
● They should have no dermatological disorders and no abnormal reactions to the exposure to sunlight.
● A section of each subject’s skin is exposed to the UV light without any protection, and one section is exposed to the radiation after the application of the sunscreen.
● A series of delayed erythemal responses are induced on a number of subsites in increments.
● These sites are assessed visually to check for the presence of an erythema (reddening of the skin) after 16 to 24 hours.
● The individual MED (min. erythemal dosage) for unprotected skin (MEDiu) and individual MED for skin protected by sunscreen(MEDip) are calculated.
● Individual SPF is defined as the ratio between MEDip and MEDiu.
● SPFi= MEDip/MEDiu
● SPF rating of a product is the arithmetic mean of the SPFi values of all test subjects.
6. Bibliography:
1. UV Light: Positive & Negative Effects (sciencing.com)
3. Ultraviolet (UV) Radiation (cancer.org)
That is why Cosmetic Testing should be done from certified Laboratories
