ABOUT AUTHOR:
Vinay Kumar Singh
General Manager-Technical,
Mikasa Cosmetics Limited,
Ahmedabad, Gujarat
vinay.s@mikasacosmetics.com
The image of a healthy person today does not necessarily include a deep, dark tan. Research has linked exposure to the sun's ultraviolet rays to skin cancer, premature wrinkles, and other skin problems like dull & lifeless skin. While protective clothing such as hats, pants, and long sleeve shirts are the most effective blocks against these damaging rays, sun-screen products provide remarkable protection for the skin.
Early civilizations used a variety of plant products to help protect the skin from sun damage. For example, ancient Greeks used olive oil for this purpose, and ancient Egyptians used extracts of rice, jasmine, and lupine plants whose products are still used in skin care today. Zinc oxide paste has also been popular for skin protection for thousands of years.
Early synthetic sunscreens were first used in 1928, and the first major commercial product was brought to market in 1936, introduced by the founder of L'Oreal.
Exposure to sunlight is beneficial as well as harmful to our body. It depends on the length and the frequency of exposure, the intensity of the sunlight and the sensitivity of the individual.
The very common effect of the exposure to sunlight include Erythema of the skin and formation of Tan. The development of Tan is a protective reaction of human body to minimize any damaging effect of solar irradiation.
There are three types of tanning.
i) Immediate tanning: This is stimulated by rays between 300 nm and 660 nm and it is maximum between 340 nm and 360 nm. It starts after about one hour of exposure and begins to fade after 2 to 3 hours.
ii) Delayed Tanning: This starts after one hour of exposure and reaches a peak after about 10 hours and fades after 100 to 200 hours. It involves the oxidation of melanin granules present in the basal cell layer of the epidermis and their migration towards the surface of the skin.
iii) True Tanning: This starts about two days after exposure and reaches a maximum about two to three weeks later.
BENEFICIAL EFFECTS OF SUNLIGHT: Moderate exposure of the human body to sunlight results, psychologically and physiologically, in a general sense of fitness, peace of mind & well-being. It stimulates blood circulation, increases the formation of hemoglobin and may promote a reduction in blood pressure. It activates vitamin D and hence prevents rickets. It reduces the susceptibility of individuals to various infections.
ADVERSE EFFECTS OF SUNLIGHT:
The adverse effects due to sunlight may be short term and long term effects.
Sun-burn: It is short-term effect which is a temporary damage of the epidermis. These may range in severity from a slight erythema to painful burns and blistering.
Chronic exposure: Chronic exposure to intense sunlight which is commonly experienced by sailors, farmers and construction workers. This may lead to more serious hazards like photo ageing, pigmentation, skin cancer etc.
SOLAR RADIATION: It consists of a continuous spectrum of wavelengths which ranges from Infrared through the visible light to the ultra violet region. The IR rays consist of wavelengths longer than 770 nm, visible light comprises of wavelengths between 400 nm to 770 nm and UV range is between 290 nm to 400 nm.
The UV range is subdivided into three bands:
i) The UV-A range which has long wave uv radiation ranging from 320 nm to 400 nm with a broad peak at 340 nm. This is responsible for the direct tanning of the skin without a preliminary inflammation, possibly due to photo-oxidation of the leuco form of Melanin already present in the upper layer of the skin. But it is weak in producing erythema.
ii) The UV-B range comprising wavelengths between 290 nm and 320 nm. It is also known as the sun burn radiation or middle UV radiation having a peak of effectiveness at about 297.6 nm. This is the erythemogenic range of UV responsible for producing sun burn and irritation reactions leading to formation of melanin and development of tan.
iii) The UV-C range which is also referred as the germicidal radiation or short UV radiation consists of wavelengths ranging from 200 nm to 290 nm. It is damaging to tissue but it is largely filtered from sunlight by ozone in the atmosphere.
The A, B and C bands of UV light emit different amounts of energy and produce an erythemal reaction at different time intervals after exposure.
The purpose of Sunscreen Products is to prevent or minimize the harmful effects of solar radiation or to assist in tanning the skin without any harmful effects.
Sunscreens may be classified according to application as,
i) Sun burn preventive agents: They absorb atleast 95 % or more of UV radiation within the range of 290 nm and 320 nm.
ii) Suntanning agents: These are defined as sunscreens which absorb at least 85 % of UV radiation within the range from 290 nm and 320 nm and a produce a light transient tan. These agents produce some erythema but without pain.
Sunscreens in the above two groups absorb a specific range of UV radiation. Same sunscreen may be employed in both product classes at different concentrations, lower in Suntan product.
iii) Opaque Sunblock agents: They aim to provide maximum protection in the form of a physical barrier. Titanium dioxide and Zinc oxide are the most frequently used agents in this group.
Depending on the mode of action, sunscreens can be classified into physical sunscreens (i.e., those that reflect the sunlight) or chemical sunscreens (i.e., those that absorb the UV light).
Sunscreen must have following properties.
1) It must be effective in absorbing erythemogenic radiation in the 290-320 nm range without breakdown which would reduce its efficiency or give rise to toxic or irritant compounds.
2) It must allow full transmission in the 300-400 nm range to permit the maximum tanning effect.
3) It must be non-volatile and resistant to water and perspiration.
4) It must possess suitable solubility characteristics to allow the formulation of a suitable cosmetic vehicle to accommodate the requisite amount of sunscreening.
5) It must be non-odorous or at least sufficiently mild to be acceptable to the user and be satisfactory in other relevant physical characteristics such as stickiness etc.
6) It must be non-toxic, non-irritant and non-sensitizing.
7) It must be capable of retaining its protective capacity for several hours.
8) It must be stable under condition of use.
9) It must not stain clothing.
Following sunscreens are used in formulating A Sunscreen Product.
para-amino benzoic acid (PABA) and its derivatives,Avobenzone, Anthranilates, Salicylates, Cinnamic acid derivatives, Dihydroxy cinnamic acid derivatives, Trihydroxy cinnamic acid derivatives, Hydrocarbons, Dibenzalacetone and
benzalacetophennone, Naphthosulphonates, Octocrylene, Dihydroxy-naphthoic acid and its salts, ortho & para hydroxy biphenyl disulphonates, Coumarin derivatives, Quinine salts, Quinoline derivatives, Uric acid and violuric acid, Tannic acid and derivatives, Titanium dioxide, Zinc oxide etc.
To know effectiveness of formulation one must be aware of various Protection measurement terms, that are being used.
The SPF rating is a measure of the fraction of sunburn-producing UV rays that reach the skin. The SPF of a product is the ratio of the time required for a person's protected skin to redden after being exposed to sun-light compared to the time required for the same person's unprotected skin to redden. For example, "SPF 15" means that 1/15th of the burning radiation will reach the skin.It basically means that a person whose unprotected skin would redden in ten minutes can apply the product and stay in the sun 15 times longer, or 150 minutes, before they get a sunburn. For Indian summer an SPF of 15 to 30 is considered best. Department of Consumer Affairs ranked various brands available in India according to its effectiveness and first 10 have SPF 30.
Persistent pigment darkening (PPD)
The persistent pigment darkening (PPD) method is a method of measuring UVA protection.
PA system
Asian brands, particularly Japanese ones, tend to use The Protection Grade of UVA (PA) system to measure the UVA protection that a sunscreen provides. The PA system is based on the PPD reaction and is now widely adopted on the labels of sunscreens. According to the Japan Cosmetic Industry Association, PA+ corresponds to a UVA protection factor between two and four, PA++ between four and eight, and PA+++ more than eight.
Star rating system
In the UK and Ireland, the Boots star rating system is a proprietary in vitro method used to describe the ratio of UVA to UVB protection offered by sunscreen creams and sprays. One-star products provide the least ratio of UVA protection; five-star products are best.
Women consumers, especially in urban areas, became well aware of the benefits of using sun protection. Hindustan Unilever Ltd under its brand Lakmé maintained lead with a value share of 32% in 2013. The company continued to leverage the brand image built over the years.
Sun care is likely to grow by a value CAGR of 4% at constant 2013 prices over the forecast period. Sun protection, which is the only category, is expected to grow over the forecast period because of the wide availability of brands and increasing public awareness of the dangerous effects of sun rays.
Sun care will largely be driven by launch of new sun care products and sun care products are increasingly accepted by consumers who prefer white and glowing skin. Latest statistics from market research by Mintel confirm that in fact Sun care category in India is already thriving, valued at 28.6 million pound in 2013,up from 19.3 million pound in 2008 and this growth is in large part due to the enthusiasm for lighter skin.
Researchers look to nature in search of the next; in sunscreen development. Some plants have natural defenses against the damaging rays of the sun. For example the single-cell alga called Dunaliella Bardawil that thrives in the Dead Sea and the Sinai desert makes its own sunscreen. Scientists at the Weizmann Institute of Science in Israel, isolated the protein that this plant produces when sunlight gets too intense. The protein acts as a solar deflector by funnelling the light. Search for many such harmless natural sunscreen is going on to satisfy the growing need & demand of Consumer.
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