Behind the label:  sun creams’ hazardous chemical cocktails
© Robert Anderson PhD
 
Originally published in Organic New Zealand, January/February 2006, Vol. 65 No. 1
www.organicnz.org
 
 
Skin cancer is the commonest cancer in this country and we have one of the highest rates of skin cancer in the world. There are nearly 50,000 new cases of skin cancers each year, including 1800 new cases of melanoma. Almost 300 people per year die of skin cancer, most from melanoma.[i] But let's not be too negative, the sun is very important to us from a health perspective.
 
The most dangerous part of sunlight is the short wavelength, which is invisible to us. This is the ultraviolet light (UV), which is radiated in addition to visible light. This radiation converts oxygen (O2), high up in the atmosphere, into ozone (O3), which in turn acts as a filter and absorbs the UV strongly. Gases that we have released into the atmosphere, especially halogen hydrocarbons and the like, have caused immense damage to Earth’s ozone layer, so more UV light gets through to Earth’s surface. This ozone layer, which was originally New Zealand’s protective umbrella, is now full of holes. The need for skin protection has become paramount. Regrettably, the main safety message about exposure is being missed.
 
According to the Cancer Society, the most skin damage caused by exposure to the sun occurs before the age of 18. This means that the chances of a person developing skin cancer later in life are somewhat influenced by their exposure to the sun during childhood years. To prevent this burning of our skin by UV, we need protection. Apart from clothing, sun creams are the obvious answer, but how well do sun creams protect against skin cancer and what should they do?
 
SPF and what sun creams should do
 
It is ironic in the extreme that although sun creams are there to protect us from skin cancer, some of their ingredients are carcinogenic.* While claiming to protect you from the sun, they may contain chemicals that cause cancer - crazy but true. Also, remember that what you put on your skin is absorbed into your body. Proof of that fact is the trick of rubbing garlic onto the soles of the feet only to taste it a short time later in the mouth. So please remember anything applied topically is equal to eating it. That said, the sun is healthy for us and boosts our health when exposed to it. So what should we look for in sun creams? For example, what is meant by the letters SPF on sun cream labels?
 
SPF stands for the Sun Protection Factor provided by the sunscreen. It refers to a product’s ability to prevent burning. The higher the number of the SPF, the longer you should be able to stay in the sun before burning. For example, if it normally takes 10 minutes of exposure for skin to get sunburned, an SPF of 15 would ideally provide 150 minutes of protection. (In actual use, protection is less because sunscreens get washed off by water and sweat.) An SPF of 15 should block more than 92 percent of the UVB rays.
 
The basic need for a sun cream is to stop the unsafe UV components of sunlight. As we have said, UV from sunlight is the main cause of skin cancer in New Zealand. (It should be noted that sunbeds[ii]can also pose a risk.) Sunlight damages the DNA that makes up the genes in our skin cells. The damage to the wrong genes can turn a skin cell cancerous. However, there are three types of UV light, called A, B and C. UV-C used to be filtered out by the atmosphere. UV-B was originally found to cause sunburn and skin cancer, but more recently, it has been discovered that UV-A can also cause skin cancer. Sun creams were originally designed to block out only UVB. Knowing that UV-A can now also cause skin cancer, we require a sun cream which blocks out a lot of UV-A as well as UVB.
 
We should realise, however, that because sun creams prevent burning, they fool people into thinking they can spend much longer in the sun. This is a mistake and can increase the risk of getting skin cancer. From aged six months on, sun cream can and should be applied on children. Most dermatologists recommend an SPF of at least 15.[iii] However, realistically, children should be applied with a much higher factor here in New Zealand.
 
What’s in the sun cream?
 
Beware, an ‘All Natural’ claim is not a guarantee that you are protected. Choosing SPF 15, 30, 45 makes no difference in protecting you from skin cancer if the ingredients themselves are irritating and/or carcinogenic. Although most sun creams are safe and function well, there are some that should be avoided if possible. The following chemicals are all potentially toxic or carcinogenic ingredients found in some sunscreens: PABA, Oxybenzone, Titanium dioxide, Padimate-O or Octyl dimethyl PABA. It may be worth just looking in some detail here.

Oxybenzone
 
According to the prestigious UK medical journal, the Lancet,[iv]in regard to oxybenzone, “It is often assumed that little or none of a topically applied substance is absorbed into the systemic circulation. We show that substantial amounts of an applied sunscreen, oxybenzone, are absorbed and subsequently excreted in human urine. Oxybenzone has low acute toxicity in animal studies yet little is known about its chronic toxicity and disposition after topical application in people. Oxybenzone is a benzophenone derivative commonly used throughout the world to make sun-products with especially high sun protection factors (SPF). . . . Our results suggest that sunscreens should not be the sole method of sun protection. It would be prudent not to apply oxybenzone to large surface areas of skin for extended and repeated periods of time, unless no alternative protection is available. There may be an additional concern for young children who have less well-developed processes of elimination, and have a larger surface area per body weight than adults, with respect to systemic availability of a topically applied dose.” What this means is that it is toxic to some degree and may not detoxify out of the body fast enough to prevent a toxic overdose.
 
PABA
 
After World War II, the qualities of para-aminobenzoic acid (PABA) became a favourite for use in sunscreens. However, it has been found that continued exposure to these types of chemicals could lead to autoimmune responses, especially systemic lupus erythematosus and dermatomyositis.[v] Reports of these concerns on the use of PABA in suncreams took place in 1964 and 1965 under the auspices of the Dermatological Association of Australia[vi], and initiated the withdrawal of PABA from sunscreens. An article from the British Journal of Clinical Pharmacology[vii]also suspected Benzophenone, ‘Absorption of sunscreens across human skin: an evaluation of commercial products for children and adults.’ “Benzophenone demonstrated sufficiently high penetration to warrant further investigation of its continued application.”
 
Titanium dioxide?
 
This is an inorganic, seemingly harmless, powder. Unfortunately, titanium dioxide is a known carcinogen. Titanium dioxide does absorb about 70 percent of Ultra Violet light, but in water this leads to the generation of hydroxyl radicals, which can initiate toxic oxidations. The University of Oxford, Department of Biochemistry, showed that all sunscreen titanium dioxide samples tested catalyse the photo-oxidation of some representative organic materials. They also demonstrated that sunlight-illuminated titanium dioxide catalyses DNA damage both in test tubes cultures and in human cells.[viii]
 
Padimate-O or octyl dimethyl PABA
 
One of the common ingredients you may find on the sunscreen label is Padimate-O or more often octyl dimethyl PABA. What do we know about these? The Department of Biochemistry at Oxford University[ix] tested them and discovered that the mutagenicity (cancer causing) of the UV-B sunscreen ingredient called Padimate-O or octyl dimethyl PABA when illuminated is safe, but only in the dark. This is not exactly on line for a sun block. In fact, the chemical becomes mutagenic in sunlight, attacking DNA directly. Thus a commercial sunscreen containing Padimate-O behaves in the same way. This suggests that, instead of protecting us, some sunscreens could contribute to UV-related cancers.
 
What to look for and some safer alternatives
 
While it is unfeasible to make an effective suncream without chemical sun screens or mineral sun blocks, it is possible to make a suncream that is low in skin irritants and without petroleum-derived polymers (plastic-like substances that ‘glue’ the cream to your skin). Products that use mineral sun blocks, such as zinc oxide, tend to be less irritating than chemical sunscreens. Good alternatives include those based on aloe vera, evening primrose oil and other natural oils. There are also some simple, but effective alternatives that can be used as UV blockers. Zinc ointment (essentially zinc in castor oil), an old stand-by, is very effective for a child’s nose, cheekbones and ears – all the bits that stick out. Further, it lasts a lost longer than many standard creams that may wash off.
 
Some of the better sun blocking creams may contain the following ingredients, all of which are safe and efficacious, not only as UV blockers, but as moisturising agents against wind, water and sunlight: zinc oxide, jojoba oil, African shea butter, hemp seed oil, neo heliopan (from cinnamon or cassia oil), bees wax, mimosa flower wax, lecithin made from soybean oil, Vitamin E oil, grapefruit seed extract, rosemary extract and ylang ylang (a natural, essential oil, botanical name Cananga odorata). The Weleda-type of products are generally much safer than cheaper brands.
 
Protection money
 
Once again, we must be aware of the industry hype when marking these products. For example, according to Pat Thomas, the health editor of the Ecologist: “Last year, the UK sun-care market generated £182million. In particular, government advice for us all to cover up has boosted the sales of higher protection factor creams. SPF 15 and SPF 25 are now the UK’s most popular choices. Unfortunately, the higher the SPF the more chemicals the cream will contain.” We can be assured that similar pressures will be brought to bear in New Zealand. That said, let’s get out this summer and enjoy the sunshine.


Robert Anderson BSc (Hons) PhD - 4 February 1942 - 5 December 2008
 

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References:
 
* Nanoparticles are now commonly used in sunscreens.
 
[ii] UVB is known to cause sunburn and skin cancer, so most sunbeds were originally designed to produce UVA only. However, recent research has found that UVA also causes skin cancers. As a result, many modern sunbeds produce far less UVA, although others still produce high levels.
[iii] An important point to note is that American SPF numbers are usually twice as high as the SPF on European/NZ creams. This means that an American SPF 8 suncream is actually equivalent to our SPF 4 suncream. Therefore purchase your creams before you go and if you have to buy there, check with a chemist.
[iv] Lancet 1997 Sep 20;350(9081):863-4 Systemic absorption of sunscreen after topical application.
[v] http://www.emedicine.com/derm/topic98.htm
[vi] Australas J Dermatol 1999 Feb;40(1):51-3 Related Articles, Books, Link Out
[vii] R. Jiang2, M. S. Roberts3, D. M. Collins2 and H. A. E. Benson,1British Journal of Clinical Pharmacology 48 (4), 635-637 © Blackwell Science Ltd
[viii] Dunford R, Salinaro A, Cai L, Serpone N, Horikoshi S, Hidaka H, Knowland J University of Oxford, Department of Biochemistry, UK. PMID: 9414101, UI: 98074912--45 Toxicol Lett 1995 Oct;80(1-3):61-7
[ix] Knowland J, McKenzie EA, McHugh PJ, Cridland NA Department of Biochemistry, South Parks Road, Oxford OX1 3QU, UK.