Sunshine and summer days are a welcome seasonal phenomenon in the aftermath of short days, cloudy skies, and a shortfall of health-giving solar radiation.
The summer sunshine that warms the earth consists of longer wavelengths of ultraviolet A (UVA) at 315 – 400nm, shorter wavelengths ultraviolet B (UVB) at 280-315nm, visible light and infrared light.
UVB consists of 3-5% of the total UV radiation that gets through the atmosphere, while UVA constitutes 95 – 97% of the radiation. Since UVB only penetrates the outer layer of exposed human skin, it is the primary cause of sunburn and non-melanoma skin cancer, such as squamous cell carcinoma. (1)
UVA on the other hand, can penetrate deeper into the skin where it causes DNA alterations, different to that caused by UVB. (2)
Despite the inclusion of UVA filters in many modern sunscreen lotions many products fail to provide protection against UVA radiation. Several studies have suggested a causal link between UVA radiation and the onset of malignant melanoma. (3)
Current scientific data documented in the American Academy of Dermatology supports this view. (4)
Despite the UVB protection of some of the modern sunscreens, as depicted by their sun-protection factor (SPF), the limited protection of UVA radiation by these sunscreens should dispel false notions of safety during bouts of prolonged sunbathing.
Sunscreen lotions are not, therefore, a reliable defence against the development of skin cancers, and do not offer immunity from developing melanoma or basal cell carcinoma. (5)
A newly published Australian study suggests that sunscreen use may reduce the risk of melanoma, (6) while earlier studies conclude otherwise, stating that melanoma risks are increased with sunscreen use and prolonged sun exposure. (7) (8).
It appears that at present there is no conclusive evidence that protection from sunlight prevents skin cancer, either by sun avoidance or outdoor sunscreen use. (9)
FDA REGULATIONS:
The Food and Drug Authority (FDA) 2007 policy on sunscreen safety regulations acknowledges that the use of sunscreen lotions alone cannot provide cancer protection, a view supported by the International Agency for Research on Skin Cancer. (10)
High SPF products do not offer the protection suggested by their labels and thereby violate FDA 2007 draft regulations that caps sun protection factors at SPF 50.
Claims of safety, as suggested by SPF 100 labeling, do not have scientific support.
PRODUCT TOXICITY:
There is evidence to suggest, that in addition to their limited protection capacity, many commonly used sunscreen lotions are potentially toxic and increase the risk of developing skin cancer.
Topical vitamin A, in the form of retinyl palmitate, ( retinol) is present in approximately 30% of popular sunscreens, and is potentially toxic, and represents a risk for skin cancer occurrence. (11)
While ingested vitamin A is a safe and effective oral anti-oxidant, its exposure to sunlight by topical application may release its photo-carcinogenic potential.
Those seeking protection during excessive sun exposure should thus avoid sunscreen products that contain retinyl palmitate, or retinol, and select products that contain zinc or titanium.
A commonly used chemical to filter out UVB is octyl methoxycinnanate (OMC) , but it is potentially toxic when exposed to sunlight.
Other potentially harmful additives to sunscreens are benzo phenone, butyl methoxydibenzoylmethane, oxybenzone, dioxybenzone, octocrylene, and octyl-methoxycinnamate.
Some sunscreens may include anti-oxidant additives, like astaxanthin and tocopherol, in an attempt to neutralize the toxic potential of some ingredients.
While sunscreen products may offer protection against sunburn, as depicted by their sun protection factor (SPF), through the inhibition of UVB radiation, their failure to block UVA radiation renders them a risk factor for basal cell carcinoma. (12)
FREE RADICAL DANGERS:
Not only are the deeper penetrating UVA rays a potential risk for DNA damage and cancer development, but also, many sunscreen lotions present a similar risk through the generation of harmful free radicals during their blockade of UV radiation. (13)
Harmful free radicals released from commonly used sunscreen lotions include oxybenzone, octocrylene, PABA and others.
Evidence suggests that many modern products, while blocking UVB radiation, have permitted high UVA exposure and failed to provide cancer protection, and may also have contributed to the risk of melanoma in some populations. (7)
EWG SUNSCREEN GUIDE 2010:
The Environmental Working Group (EWG) lists more than 1,700 top rated sunscreens that claim to provide broad-spectrum (UVA and UVB sunburn) protection, with only 1 in every 5 passing the safety test for protection. (14)
The FDA have yet to address the potential toxicity of commonly used sunscreen filters, and approve a selection of products that have minimal toxic protection, and optimal protective capacity through the inclusion of zinc or titanium minerals, which offer some protection without the release of free radicals.
Lip balms, likewise, should be chosen with consideration for EWG recognition ratings. (See the EWG Sunscreen Guide).
PROTECTIVE NUTRIENTS:
Sun avoidance, as advocated by many health authorities, is potentially more harmful that sun exposure.
Evidence from several studies over the past two decades suggests that the increasing numbers of human cancers that have been documented are linked to low vitamin D levels, arising from fearful avoidance of sun exposure. (15)
The main source of protective vitamin D in the human body is sunshine, and its protective role in gene regulation is now well established. (16)
Limiting sun exposure to 20 – 30 minutes prior to application of a safe sunscreen, or clothing protection, may be the ideal choice for protection, while optimizing vitamin D production.
In the absence of adequate sunlight, as during the winter months, vitamin D should be taken as an oral supplement, and dosages of 2000 units to 5000 units, or more, may be required to maintain protective blood levels in the region of 50 – 80 ng/ml.
OMEGA 3 PROTECTION:
Omega 3 supplementation, in the form of EPA/DHA may provide added protection by inhibiting the development and progression of a range of human cancers, including melanoma.
Epidemiological, experimental and mechanistic data demonstrate the inhibiting effect of EPA in cancer development and progression, and implicate Omega 6 as a stimulant of such processes.
An imbalance of excessive Omega 6 intake (vegetable oils) relative to Omega 3 (fish oils) presents a risk for several chronic diseases, including cancer. (17)
Omega 3, but not Omega 6, inhibits AP-I activity and cell transformation in JB6 cells, a process that leads to cancer development. (18)
A daily exposure to sunlight of 30 minutes is likely to generate healthy levels of circulating vitamin D, in the absence of which oral vitamin D should be taken on a daily basis.
EPA (Omega 3 marine oils) provides added protection against skin cancer in dosages of 1000mg daily.
CONCLUSION:
The conventional health warning to “cover up and stay out of the sun” during the summer months, or to cover sun exposed skin with liberal applications of high SPF sunscreens, is without sound scientific basis, and may be a hindrance rather than a help to health maintenance.
Following such advice is likely to lead to severe deprivation of vitamin D, with dire consequences for health.
The risks for compromised health and diminished protection against a wide range of debilitating human disorders, which may include heart disease and cancer, are greater for sun avoidance than for sun exposure.
Sunlight is the best source of natural vitamin D.
The added risks for cancer are increased by the liberal application to the skin of several popular, and unsafe, sunscreens, and their labels should be carefully scrutinized to detect the presence of harmful toxins which may be potentially carcinogenic.
Safe and Unsafe sunscreens are listed on the EWG website . (See Hall of Shame). (14)
Blood levels of vitamin D3 should be evaluated to determine risk status, and controlled sun exposure, avoiding sunburn, should be encouraged by healthcare professionals, and routinely practiced as part of a healthy lifestyle habit.
Alternatively, oral supplementation with vitamin D3, for infants and the elderly, and all ages in between, should be encouraged as part of a healthy dietary regimen.
Dr. Neville S. Wilson.
The Leinster Clinic.
June, 2011.
REFERENCES:
- Von Thalen 2010.
- Mut Res/ Fundamental & Molecular Mech of Mutagenesis, vol 571, issues 1-2, 1 April, 2005. J.Cadet.
- Photoderm, Photoimmun & photomedicine, Runga, 1999.
- J of Am Acad of Dermatology, 2001. Wang, et al.
- B J of Dermatology, 2009.
- J of Clinical Ontology 2010, 29: 257-263.
- Ann Epidemiol 17 (12): 956-63, Gorham, E.D.
- Am J.Public Health. 82 (4): 614-5
- National Cancer Institute 2009.
- U S Food & Drug Admin (FDA) 2007.
- National Toxicology Programme – www.ewg.org
- B J of Dermatology, 2009.
- Damiana 2007/2010, Hiddaka 2006 Serfone, 2002.
- EWG Sunscreen Guide 2011.
- Grant 2009, Tang 2010.
- Mead 2008.
- Cancer Res. 2000 Aug, 1:60 (15): 4139-45
- Proceeding of the National Academy of Sciences, June 19, 2001.
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