Chemical Sunscreens Include:
Benzophenones (dixoybenzone, oxybenzone);
PABA and PABA esters (ethyl dihydroxy propyl PAB, glyceryl PABA, p-aminobenzoic acid, padimate-O or octyl dimethyl PABA);
Cinnamates (cinoxate, ethylhexyl p-methoxycinnamate, octocrylene, octyl methoxycinnamate);
Salicylates (ethylhexyl salicylate, homosalate, octyl salicylate);
Avobenzone[butyl-methyoxydibenzoylmethane; Parsol 1789] - This is the only chemical sunscreen currently allowed by the European Community. However, its safety is still questionable since it easily penetrates the skin and is a strong free radical generator.
Sunscreen Chemicals May Generate Free Radicals Within Your Body
Most chemical sunscreens contain, as UVA and UVB blockers, from 2 to 5% of compounds such avobenzone, benzophenone, ethylhexyl p-methoxycinnimate, 2-ethylhexyl salicylate, homosalate, octyl methoxycinnamate, oxybenzone (benzophenone-3) as the active ingredients.
Benzophenone (and similar compounds) is one of the most powerful free radical generators known. It is used in industrial processes as a free radical generator to initiate chemical reactions.
Benzophenone is activated by ultraviolet light energy that breaks benzophenone's double bond to produce two free radical sites.
The free radicals then react with other molecules and produce damage to the fats, proteins, and DNA of the cells - the types of damage that produce skin aging and the development of cancer.
Adding to the problem is that large amounts of applied sunscreens can enter the bloodstream though your skin. In the 1970s, Prof. Howard Maibach warned that up to 35 percent of sunscreen applied to the skin can pass through the skin and enter the bloodstream but this had little effect on sunscreen promotion or safety testing.
The longer sunscreen chemicals are left on the skin, the greater the absorption into the body. This may be a factor in the large increases in cancer (breast, uterine, colon, prostate) observed in regions, such as Northern Australia, where the use of sunscreen chemicals has been heavily promoted by medical groups and the local governments.
Many sunscreens also contain triethanolamine, a compound that can cause the formation of cancer causing nitrosamines in products by combining with nitrite used as preservative and often not disclosed on sunscreen labels.
In March 1998, Dr. John Knowland of the University of Oxford reported studies showing that certain sunscreens containing PABA and its derivatives can damage DNA, at least in the test tube experiments.
When a chemical sunscreen, Padimate-O, was added to DNA and the mixture exposed to the ultraviolet rays of sunlight, it was found that the sunscreen broke down in sunlight, releasing highly active agents that could damage DNA. It did not block out the UV, but instead absorbed energy.
"It became excited and set off a chemical reaction that resulted in the generation of the dangerous free radicals and broken DNA strands that can lead to cancer," he said and further commented that while it's too early to make blanket recommendations, "I would not use a product containing PABA, Padimate-O or other PABA derivatives."
Dr. Martin Rieger reported that PABA may play a role in DNA-dimer formation, a type of DNA damage that can induce carcinogenic changes.
Avobenzone (Parsol 1789) May Not Be Safe Either
In 1997, Europe, Canada, and Australia changed sunscreens to use three specific active sunscreen ingredients - avobenzone (also known as Parsol 1789), titanium dioxide, and zinc oxide - as the basis of sunscreens.
In the USA, the cosmetic companies have held off this policy as they try to sell off their stockpiles of cosmetics containing toxic sunscreens banned in other countries.
However, avobenzone is a powerful free radical generator and also should have been banned. Avobenzone is easily absorbed through the epidermis and is still a chemical that absorbs ultraviolet radiation energy.
Since it cannot destroy this energy, it has to convert the light energy into chemical energy, which is normally released as free radicals.
While it blocks long-wave UVA, it does not effectively UVB or short-wave UVA radiation, and is usually combined with other sunscreen chemicals to produce a "broad-spectrum" product. In sunlight, avobenzone degrades and becomes ineffective within about 1 hour.
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