Opinion – November 29, 2009

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How Toxic Is Your Sunscreen?

by Dr Peter Dingle (BEd, BSc, PhD)

>During the past 50 years, we have increased the number of synthetic sunscreen chemicals that we use. We have done this with virtually no consideration as to how vulnerable we are to these chemicals, how little we know about their subtle and cumulative toxic effects or the effects of interactions of these chemicals. We assume that because they are so easily purchased from the supermarket shelf, they must be safe to use. Wrong! Many of these chemicals are known to be toxic; very few are carefully studied before they are put on the shelf and made available to the general public. In fact, some of these chemicals have been used for decades without any deliberation about their potential toxic effects.

There is no doubt that the products in everyday sunscreens are toxic. The only real question is: what effects do they have on you and your family? Exposure to these chemicals affects you on a cellular level. It may be insignificant or it may actually be contributing to the problem you are trying to avoid.

The majority of sunscreens on the market are full of toxic ingredients that may be worse than the exposure to the sun or may be contributing to long term health problems.

Background
Since the 1970s, global use of sunscreens and ingredients used in these products has increased dramatically in response to growing awareness about UV exposure and its negative effects on the skin 1,2. However, there is also increasing acknowledgement of the toxic effects of many sunscreen ingredients, with some already being removed from production in various countries. In addition to use in sunscreen lotions, many of the same chemicals are increasingly being added to a range of cosmetics and skin care products including moisturizers, foundations and
lipstick 3,1,4,5. Thus, virtually every member of the public is exposed to these chemicals, as so many products containing them sit in our cupboards.
In order to block out UV radiation, the active ingredients must react to sunlight and, by its very nature, this reaction will cause energy to be released, which is where the problem begins. Little is known about this energy and how it is being released back into the body or what it can do to the cells of the body 6. UVA absorbers have a high level of photochemical instability””that is, when exposed to sunlight, they begin to produce free radicals 7. These free radicals cause DNA damage, which can result in a range of ill effects from premature skin aging to cancer 8. Padimate O, para-aminobenzoic acid and 2-ethylhexyl-pmethoxycinnamate, when illuminated by sunlight, generate singlet oxygen, a
potent free radical that has the potential to cause DNA damage, including strand breaks, when in contact with human cells 8,9.

Sunscreen Toxicity

The general consensus is that sunscreens are a highly important means by which one can avoid excessive UV irradiation and subsequent sunburn, thereby reducing the risk of developing melanoma or other forms of skin cancer later in life.

However, there is growing concern regarding the impact that the ingredients contained in sunscreens have on the body 10. Laboratory tests on the main ingredients of conventional sunscreens have revealed that they are associated with some surprising negative side effects, including: increased skin permeability; endocrine activity resulting in a disruption of natural hormone levels; the generation of free radicals and subsequent damage to cellular DNA within skin cells; and potential skin cancer 11,12,13. In some cases the active ingredients in sunscreens may outweigh the benefits. Alarmingly, it is the unseen active ingredients that most consumers would not even think to check that are harmful.

While the toxicity of the main ingredients is of concern, there is just as much concern that the full list of ingredients in these products is not disclosed in Australia. Further, the potential for their interaction is, at this point, not brought to
the attention of the consumer.

Do Sunscreens Increase Skin Cancers?

The question of whether sunscreen prevents skin cancer remains unanswered.Many epidemiological studies show an increased risk of skin cancer to the sunscreen user 14. A review of studies on skin cancer and sunscreens by Science
News found that people who used sunscreen were more likely to develop basal cell cancer than people who did not. Science News reviewed ten studies of melanoma, five of which concluded that people who used sunscreen were more likely than non-users to develop melanoma. Three of the studies found no association between melanoma and sunscreen use, and two studies found that people who used sunscreen were the most protected. Science News revealed that epidemiological data were not conclusive. This may be because people involved in the studies were not wearing effective sunscreen or were staying in the sun for long periods of time because they thought they were protected. There may be other factors that were not considered in the studies. Science News’ review highlights the difficulty in
interpreting epidemiological studies of humans. More recently, results of a randomized controlled trial of adults who used sunscreen daily found increased risk of basal cell carcinoma 15. A case-control study from southern Sweden of 571 patients diagnosed with malignant melanoma showed significantly increased risk for having developed the disease after regular sunscreen use 16.
The possibility remains that these products may be contributing to skin cancers. This is supported by the fact that the toxic chemicals used in sunscreens could very well constitute a potential mechanism for the development of skin cancers.

Toxic Ingredients
Many of the chemicals in sunscreens have minimal toxicological effects when first applied to the skin. However, once exposed to sunlight, the chemicals are heated and reactions occur between the sunscreen’s active and inactive ingredients and the epidermis 17.

• Titanium dioxide
• Octyl-methoxycinnamate(OMC)
• Methylbenzylidene camphor (4-MBC)
• Cinoxate (2-ethoxy ethyl p-methoxycinnamate) and methyl sinapate
• (methyl 3,5-dimethoxy 4- hydroxycinnamate)
• Benzophenones
• Oxybenzone (benzophenone 3)
• PABA (para-aminobenzoic acid)
• Padimate O
• Dibenzoylmethanes
• Parsol 1789 (Avobenzone)
• Octyl salicylate
• PBSA (2-phenylbenzimidazole-5-sulfonic acid)

Excipients: The Unlisted Chemical Dangers
There is cause for concern not only about the active ingredients in sunscreens, but also about the inert ingredients, particularly in Australia as there is no requirement for these to be listed on sunscreen labels. Excipients, which act as the carriers or base materials of a product, make up approximately 80% of sunscreens. They “receive” and carry the other ingredients. Excipients include mineral oil, petrolatum, isopropyl esters, lanolin derivatives, aliphatic alcohols, emulsifiers, fragrances, thickeners and preservatives. Sunscreen toxicity, including contact allergies 61, can be
caused by excipients in the formulations 60.

The absorption of sunscreens depends on many factors including where it is applied. The face is probably the most common place of sunscreen application and  it absorbs sunscreens at a rate of two to 13 times that of the skin on the forearm 80.

Penetration enhancement
When used in conjunction with other chemicals, sunscreens can act to speed up the penetration of other substances including increasing the transdermal absorption of toxic chemicals 81. A large proportion of the active ingredients in sunscreens can act individually as penetration enhancers. However, when combined, the adverse effects can be significantly enhanced 12. In a number of studies sunscreens have enhanced the penetration through the skin of pesticides such as 2,4 dichlorophenoxyacetic acid (2,4-D), paraquat, parathion and malathion 82,83 and
industrial solvents 84.

Slip, Slop, Slap and Salad: The Diet Link
The human skin can naturally protect itself from photodamage by antioxidants 87. Humans have evolved in the sun. This does not mean being in the sun all day but we have an innate ability to protect ourselves from damaging sunrays and, in the meantime, produce the all-important vitamin D. Good nutrition enables the body to repair certain amounts of damage to the DNA from the sun. So while it is important to get out into the sun each day for short periods to get adequate vitamin D, it is equally important to get good nutrition to reduce the risk of skin cancers and skin complaints brought about by the sun’s rays. This involves more fruit, vegetables, nuts and beans””foods that are rich in antioxidants, vitamins, minerals and so much more. It would be naive to think that nutrition, which provides the
building blocks of our physical and chemical bodies, has no role in the protection of our cells. It would also be naive to think that nutrition alone would protect us, but it does play a role. Recent research has shown that B carotene supplementation for 10 weeks provide an SPF around 4 and significantly reduced sunburn 88.

Of all the naturally occurring chemopreventative agents present in the diet, the polyphenolic catechins found in green tea have been identified as the most effective botanical agents for use in the prevention of photodamage and skin cancer 89. Tea catechins are non-nutritive compounds, however their consumption has repeatedly been demonstrated to inhibit or decrease the severity of UV damage in laboratory trials 90,91,92,93.

Safer Barriers
A number of products are now available that afford the same sun protection as synthetic, toxic sunscreen ingredients but with a much reduced risk. A black tea extract gel developed for potential protection from UV damage was found to prevent erythema and acute sunburn due to direct sunlight (UVA, UVB) as well as to repair DNA damage inside the skin when an enzymatic oxidation of tea polyphenols occur 94. Unlike the gel, sunscreens protect the skin only from incoming UV radiation and have no damage repairing effects inside the skin after exposure (in addition, the sunscreens have toxicological qualities). The black tea gel can be applied liberally and regularly to the skin without toxic side effects.

Natural sunscreen used in combination with chemoprevention (such as green tea phenol extracts that have been shown to reduce DNA damage in human cells) suggests that UV radiation-induced sun damage can be prevented 95,96.
Human skin is capable of absorbing various nutrients directly. Clinical studies have indicated that tea polyphenols are readily absorbed when topical applications are applied to the skin 97,98. Formulations containing products such as vitamin A, vitamin E, lycopene and green tea are at present readily available on the cosmetic market. Perhaps it would be prudent to encourage high-risk individuals to apply these products to their skin in order to reduce their exposure to free radical damage and subsequent skin cancers and to soothe the pain and inflammation associated with inadvertent sun exposure 89,92.

Zinc oxide is considered considerably safer than titanium dioxide and covers the full UVA and UVB spectrum from 290 to 400nm””the most complete spectrum.

Microfine zinc oxide is less white than titanium dioxide as a sunscreen ingredient and it is more protective against long wave UVA 99. Unlike the synthetic chemical sunscreens and titanium dioxide zinc oxide is photostable 105.

How to select safe ingredients
Read the ingredient list and label and buy only products that list all ingredients.
The list will be at least 10 items long and in most cases much longer.

When natural is not natural The claim of being “natural” can be very misleading. Even more misleading, the
term “natural” can be a part of the name of a product and therefore not necessarily a claim! Perhaps a better approach is to ask for products that are free from synthetic chemicals. Claims of being chemical-free usually imply this but are not really precise enough. Everything is made from chemicals, so “chemical free” is not possible.

Organic products are best
The term “organic products” refers to products that have an extremely high level of certification and quality assurance. This means a lot of work has already been done to validate their safety. None of the toxic ingredients I have listed in this book as are permitted under organic certification. To find the safest sunscreens, look for products that resemble food ingredients like some of the safer ones I have listed above. This would include a plant-based oil,
green tea and vitamin E. In the future all sunscreens will be made of edible ingredients probably with a little zinc oxide thrown in for good measure.

Environmental Concerns
It has been demonstrated that personal care products, including sunscreens, have an impact similar to that of other contaminants on aquatic organisms 100. During bathing or swimming, a significant amount of sunscreen is washed off and enters the aquatic environment 101. The high lipophilicity of the UV filters has been shown to cause bioaccumulation in fish and humans, leading to environmental levels of UV filters that are similar to those of PCBs and DDT. Fish species in a German lake contained evidence of six different UV filters in addition to PCBs and DDT at similar levels. This accumulation in humans and the environment suggest that UV filters should be considered relevant environmental contaminants 102. Even in relatively low levels, the lipophilic (fat loving) nature of these substances
suggests that they may accumulate along food chains where they may have an estrogenic impact on top-order consumers 10,25. A laboratory study conducted on the impact of UV-absorbing compounds on mammalian and amphibian cells revealed that extremely low concentrations of 4-MBC possessed an estrogenic effect on cells and were able to alter gene expression 28. Even at the low levels observed, these compounds may be having a significant impact on the ecology of aquatic environments 101.
Recent studies have raised the issue of sunscreens having a serious negative effect on coral reefs. Laboratory experiments conducted in several tropical regions (the Atlantic, Indian and Pacific Oceans and the Red Sea) showed that sunscreens cause the rapid and complete bleaching of hard corals, even at extremely low concentrations. By promoting viral infection, sunscreens potentially play an important role in coral bleaching in areas prone to high levels of recreational use by humans 100.

The Politics of Sunscreens and Skin Cancers
It is widely acknowledged throughout the sunscreen industry and by various cancer authorities that the ingredients in sunscreens may be causing the same problems that they are meant to solve. Despite this, the industry maintians a strong outer appearance of compliance and denies any problems.
Individuals and organisations are quick to dismiss the real results of toxicological studies of sunscreen ingredients and believe that the widespread usage of sunscreens without any immediately apparent negative or acute impact is
testimony to the fact that these products are harmless. However, laboratory results suggest that long-term exposure to these compounds may result in chronic effects on human health and reproduction 4,13,25,29.
It is a paradox and interesting to note that some of these same organizations try to convince people not to smoke due to the presence of potentially toxic chemicals and promote products that are considered as toxic, just not as well researched.

Conclusion
Sunscreens should not be abused in an attempt to increase time in the sun. The misuse of sunscreen has led to a false sense of protection to prolong relaxation in the sun. The development of sunscreens that protect against both UVA and UVB were major steps forward in preventing skin damage 50 years ago. However, it is now time to move to ingredients that do not contribute to the problem. Poor chemical photostability of many sunscreens is now recognized as a common problem. In addition to losing effectiveness they can become photo-oxidizing agents that damage DNA in skin cells. The research in this report shows that using synthetic chemical sunscreens to help prevent sun damage may be more harmful than not using any protective chemicals.
Most sunscreens are only slightly updated products of the 1950s. It would appear that little progress has been made in the development of more effective UV blockers, in spite of growing concern over UV exposure and the toxicity of
sunscreens. Despite the widespread belief that sunscreen usage is essential in the fight against melanoma, the results of laboratory studies on the toxic and estrogenic effects of the major sunscreen ingredients suggest that their use is not
without inherent risks. Effort should be directed at the development of safer sunscreens, which are more appealing to consumers and pose a smaller risk to their health.
There are also many assumptions made which enable these chemicals to be poorly regulated. Two of the most critical, but incorrect, assumptions are that little or none of a topically applied substance is absorbed into the systemic circulation and that because they have been around for so long they must be safe.
It is critically important to produce safe, effective sunscreens that can be applied liberally and regularly to the whole body. “User-friendly” sunscreen would require that the sunscreen be made using low-toxicity ingredients such as food grade ingredients that repair UV damage while protecting from UV exposure 94,103. The evidence suggests that these ingredients, used in combination with chemoprevention such as green tea phenol extracts, have been shown to reduce UV DNA damage in human cells 95,96. Choose sunscreens that are free from synthetic chemicals. We should be making sunscreens from the foods we eat. Then we would know that they are safe.
It is a common misconception that sunscreen use alone is sufficient to protect the skin from the effects of UV damage; in fact, this is not the case 16. More reliable forms of UV protection must be used in conjunction with safer sunscreens in order to minimise the risks associated with chronic exposure to UV radiation, especially amongst individuals with naturally low defences against solar radiation104,16. More desirable means of protection include wearing long-sleeved clothing, seeking shade during periods when the UV index is at its highest and conducting outdoor activities during the early morning and late afternoon so as to avoid the sunniest part of the day 16. In preventing sunburn and skin cancer, the key is to remember that sunscreen should be used in conjunction with protective clothing, a hat, sunglasses and a healthy diet. The use of sunscreens should never be considered as a safe way to spend all day in the sun.

A Final Word
Only through consumer pressure will the bigger companies change to safer, less toxic ingredients in sunscreens. Science has never been enough to change the world””it can only help individuals make better choices.
Now that you have this information, you can make better choices and live a healthier, safer life. There is nothing more important than your health. By producing this information my aim is not to drive people out into the midday
sun without protection. Rather it is to get people to think twice about the products they use. My simple rules are:
1. We all require some sun exposure every day for the production of vitamin D so we should be out in the sun for a brief period, depending on our skin type, in the early or late hours of the day. A little bit of sun is essential for good health. Too much does the opposite.
2. We should cover up in preference to using sunscreens, finding shade and using hats and long-sleeve sunshirts.
3. We should use the safest sunscreens with the least toxic ingredients containing organic plant based ingredients. It is not just good science but also common sense to go for safer ingredients and a safer product when it is available.
4. Eat more fruit, vegetables, nuts and beans to increase your natural sun protection factor and ability to repair damaged skin, not to mention prevent chronic illness of all types.

This is an edited version of Peter’s report. To read the full report, including a list of all the references used in his research visit his website http://www.drdingle.com/

Peter is an Environmental and Nutritional Toxicolgist. He is Associate Professor and leading researcher in Health and the Environment at Murdoch University. He has published more than 100 scientific papers on toxic chemicals and health. His first publication on toxic chemicals used in cosmetics was “Dangerous Beauty” in 1999 which has now sold more than 30 thousand copies. In “Dangerous Beauty” he raised the spectre of toxic ingredients in sunscreens and has spent the last 8 years gathering more information on this topic.