UV Filters

• UV Filters are ingredients which absorb, reflect, scatter and block ultraviolet radiation.
• They are formulated into personal care products to protect skin and hair from the damaging effects of sunlight.
• UV filters are also used as stabilizers, to protect the integrity of the finished products (color and fragrance).

• UVB filters
• UVA filters

• Cinnamates
• Benzophenones
• PABA derivatives
• Salicylates
• Physical UV blockers (Titanium Dioxide, Zinc Oxide)
• Dibenzoylmethane (Parsol® 1789)

• The wavelength of the UVB band is between 290 to 320 nm.
• Penetration is mostly into the epidermis.
• The most active UV radiation in producing erythema.
• UVB is called the sunburn radiation.
• UVB is considered to be primarily responsible for induction of skin cancer due to damage to DNA.
• UVB (and UVA as well) is suspected to affect the Langerhan cells in the epidermis and , therefore, the immunologic defense

• The wavelength of the UVB band is between 320 – 400 NM
• The UVA band is divided into two subsets:
• UVA II       320 – 340 NM
• UVA I        340 – 400 NM
• Ten times more UVA reaches the Earth's surface than UVB.
• UVA penetrates deeper into the skin than UVB, thereby having a stronger effect on the dermis.
• UVA radiation produces damage to cellular proteins, lipids and carbohydrates.
• UVA radiation involves generation of singlet oxygen and hydroxyl radicals.
• The lethal action of UVA on mammalian cells is strongly dependent on the presence of oxygen.
• Although DNA absorption of UVA is weak, it can cause structural changes in the DNA molecule (crosslinking).
• Researchers suggest UVA II (320 – 340 NM) in the most damaging to blood vessels.

• In response to the increased awareness to the adverse effects of sunlight, biological procedures for quantifying sunscreen effectiveness have been developed in the United States, Australia and Europe.
• Differences exist among methods.

• The Sun Protection Factor (SPF) is defined as:

"The UV energy required to produce a minimal erythermal dose (MED) on protected skin, divided by the UV energy required to produce MED on unprotected skin".

            MED - protected skin

SPF Value = __________________________

            MED - unprotected skin

• MED (Minimal Erythymal Dose) is defined as:

"The quantity of radiant energy required to produce the first perceptible redness with clearly defined borders, assessed 16–24 hours after UV exposure."

• Skin Type
• UV intensity-irradiation dose of UVB, UVA, latitude, altitude, reflection, and cloud cover
• Radiation source – emission spectrum
• Concentration of sunscreen actives
• Vehicle – formula composition
• Properties of applied film – uniformity, spreadability, thickness
• Physical/chemical properties of sunscreens – substantivity, percutaneous absorption
• Environment – temperature, humidity, direct and scattered radiation
• Sweating – skin temperature, amount inorganic salts present
• Swimming – duration of swimming
• Testing procedures – errors in erythema visualization
• Photosensitizers – reddening of the skin can lead to false results

• Parsol® MCX – Octyl Methoxycinnamate (OMC)
• Parsol® HS – Phenylbenzimidazole Sulfonic Acid
• Parsol® 340 – Octocrylene
• Parsol® 5000 – 4-Methylbenzylidene Camphor
• Parsol® SLX – Benzylidene Malonate Polysiloxane

• Parsol® 1789 – Butyl Methoxydibenzoylmethane, Avobenzone