Summaries of Scientific Studies

"Is Chronic Sunlight Exposure Important in Accounting for Increases in Melanoma Incidence?" Richard P. Gallagher, J. Mark Elwood and C. Paul Yang. International Journal of Cancer, 1989.

Most attempts to relate sunlight exposure to the increase in malignant melanoma have concentrated on the positive association between intermittent exposure to sunlight and risk of melanoma. The Western Canada Melanoma Study, however, detected an opposite association between melanoma and chronic or long-term occupational sun exposure in men, with the lowest risk in those with the most occupational exposure. The findings suggest that sun exposure may be protective.

Data obtained from Canadian census figures indicated that since 1961 there has been a substantial reduction in the number of men who work outdoors in Canada. These observations suggest that part of the increase in the incidence of melanoma in low-sunlight areas may be due to a reduction over the past 40 years of the size of the group "protected" by their exposure to UV light. It is known that sun exposure tends to thicken the epidermis and lead to a year-round tan. Both of which afford protection of the underlying melanocytes from the effects of the sun, thus perhaps providing an explanation for the lower incidence of melanoma among outdoor workers.

The Danish Case-Control Study of Cutaneous Malignant Melanoma." A. Osterlind, M.A. Tucker, B.J. Stone, and O.M. Jensen. International Journal of Cancer, 1988.

A population-based case-control study of 474 patients with cutaneous malignant melanoma and 926 population controls, conducted in East Denmark over a 3-year period included an evaluation of the relationship of UV-light exposure to cutaneous melanoma risk. A significant decrease in risk was associated with occupational exposure during the summer in males. No association was found between the risk of cutaneous melanoma and exposure to artificial UV-light (fluorescent light, sun lamps, or tanning beds).

"Vitamin D3 and Sunlight An Intimate Beneficial Relationship" M.F. Holick, Ph.D., M.D. Biologic Effects of Light, 1992.

Vitamin D is absolutely essential for the health and maintenance of the skeleton. Vitamin D deficiency in children causes rickets. In adults, it causes metabolic bone disease. It has been estimated in the United States that about 30 to 40 percent of elderly persons with hip fractures are vitamin D deficient. Although aging does not decrease the body's efficiency to absorb vitamin D, the aged often do not obtain sufficient vitamin D in their diet to meet their body's requirement. In the United States, the principal food source for vitamin D is milk. If an adult does not consume milk or fish oils that contain vitamin D or take a vitamin D supplement, it then becomes essential for that person to sunbathe to generate enough vitamin D to satisfy the body's requirement. When humans are exposed to sunlight, the high-energy ultraviolet B photons strike the surface of the skin and a biochemical reaction forms vitamin D.

"Personal Risk-Factor Chart for Cutaneous Melanoma" Rona MacKie, T. Freudenberger, T.C. Aitchison. The Lancet, 1989.

Information from a case-control study of patients with malignant melanoma diagnosed in Scotland in 1987 has been used to derive a personal risk-factor chart that can be used by both the medical profession and the general public. The four strongest risk factors for melanoma were determined to be the total number of benign pigmented naevi (birthmarks); a tendency to freckle; the number of abnormal naevi; and a history of severe sunburn at any time in life.

Although 13 male and 20 female melanoma patients had used artificial sources of ultraviolet radiation, compared with 1 male and 7 female controls, the authors of the study did not find sufficient correlation between exposure to artificial ultraviolet light and the incidence of malignant melanoma to include artificial ultraviolet light exposure as a significant risk factor for melanoma.

"Vitamin D and Breast Cancer Risk" Ester M. John and Associates at the Northern California Cancer Center

The study shows that casual sunlight, along with other factors, can help reduce the risk of breast cancer. In the report the authors stated, " ... we found that high exposure to sunlight was associated with a 25 percent to 65 percent reduction in breast cancer risk among women whose longest residence was in a state of high solar radiation." The report also says, "No reductions in risk were found for women who lived in regions of low solar radiation.

"Geographic patterns of prostate cancer mortality-evidence for a positive effect of UVR" by Hanchette and Schwartz of the University of North Carolina published in the journal Cancer

The study supports the hypothesis that UVR may protect against clinical prostate cancer. Viewed with other recent data, including those demonstrating a differentiating effect of vitamin D on human prostate cancer cells, these findings suggest that vitamin D may have an important role in the natural, history of prostate cancer.

In their article, Hanchette and Schwartz stated a number of important findings. For instance, they stated, "because the major source of vitamin D is casual exposure to UVR, the authors examined the geographic distributions of UVR and prostate cancer mortality in 3,073 counties of the contiguous United States." The study found that "the geographic distributions of UVR and prostate cancer mortality are correlated inversely. Prostate cancer mortality exhibits a significant north-south trend, with lower rates in the south."

The study's data also showed there was a 20-percent to 40-percent lower incidence rate of prostate cancer among men in southern latitudes, while men with skin type 6 skin (African Americans) had a much higher incidence rate in all areas than did skin type 1-4 men (Caucasian).

"Sunbed use and risk of melanoma: results from a large multicerntric European study" by Autier, De Vries, Eggermont, Coebergh, Ringborg, Bandberg, Bataille and Grivegnee presented at the Luxembourg Health Institute, Luxembourg, The Netherlands.

"The study objective was to assess whether there is an association between sunbed use and cutaneous melanoma in subjects 18-49 years old. In a case-control design, we compared past sunbed and sun exposure of 622 incident melanoma cases, to the exposure experienced by 649 controls recruited in six European countries, from April 2000 until June 2002. Levels of sunbed used were higher than in any former study on the same topic. HOWEVER, NO EVIDENCE WAS FOUND FOR AN ASSOCIATION BETWEEN SUNBED USE AND MELANOMA. No result suggested a dose-response curve, and no association was even present for subjects reporting more than 35 hour of cumulated sunbed use and/or who started their sunbed use AT LEAST 19 YEARS before the interview. OUR STUDY DOES NOT SUPPORT THE POSSIBILITY THAT SUNBED USE COULD INCREASE THE MELANOMA RISK."

Skin colour and skin cancer - MC1R, the genetic link, by Sturm RA, published Melanoma Res 2002 Sep;12(5):405-416

Pigmentary traits such as red hair, fair skin, lack of tanning ability and propensity to freckle (the RHC phenotype) have been identified as genetic risk factors for both melanoma and non-melanocytic skin cancers when combined with the environmental risk factor of high ultraviolet light exposure.

"Mutations in the TP53 gene in human malignant melanomas derived from sun-exposed skin and unexposed mucosal membranes," by Ragnarsson-Olding BK, Karsberg S, Platz A, Ringborg UK. Published in Melanoma Res 2002 Sep;12(5):453-463

Mutations in the p53 tumour suppressor gene ( ) have been linked to several types of cancer. We therefore investigated whether such mutations occur in malignant melanomas and, if so, whether they are linked to ultraviolet (sun) light exposure. For the first time, mutations in mucosal membranes and adjacent tissues shielded from sunlight were compared with those in cutaneous melanomas from sun-exposed skin. Archival tissues were obtained from 35 patients with a primary melanoma taken from unexposed mucosal areas and from 34 patients with a primary melanoma located in chronically sun-exposed head and neck skin. was characterized by means of polymerase chain reaction amplification and single-strand conformation polymorphism assay followed by nucleotide sequencing. The results showed that 17.6% of the primary cutaneous and 28.6% of the primary mucosal melanomas had point mutations in. Among the cutaneous melanomas, one showed three mutations in exon 7, and one had two mutations in exon 5; the mutation was in the same allele in both cases. One mucosal melanoma had two mutations in exon 7, both in the same allele, and another had two mutations, one in exon 7 and one in intron 6, both in the same allele. C<--T mutations at dipyrimidine sites, considered fingerprints for ultraviolet light-induced mutations, were about equally distributed among patients with melanomas from chronically sun-exposed areas [six out of nine; 67%) and those with melanomas from unexposed mucosal areas and adjacent skin [eight out of 14; 57%). Our data, demonstrating the presence of such mutations even in melanomas from mucosal membranes, clearly suggest that factors other than, or additional to, ultraviolet radiation are operational in the induction of mutations in melanomas

"Summer Sun Can't Sustain Vit. D Levels Year-Round" by M. Janet Barger-Lux, Senior Research Associate, and Dr. Robert Heaney, Osteoporosis Research Center Creighton University Medical Center, 601 North 30th Street Omaha, NE 68131-2197, Sept. 24, 2002

Counting on the sun alone for vitamin D will leave most people deprived of adequate amounts of this nutrient, especially during the winter in the northern parts of the US, researchers report. This is true even for people who work outside during the summer and get plenty of sun in the warmer months but not in the winter, according to study results presented here at the annual meeting of the American Society for Bone and Mineral Research.

Vitamin D is formed in the skin, but it requires ultraviolet rays of the sun to activate it to a form the body can use. Vitamin D, which assists the intestines in absorbing calcium and phosphorus, is also contained in some fortified foods.

They brought the men back about 6 months later to assess how much vitamin D they may have lost over the winter. The team estimated that the amount of vitamin D that the group had received from the sun during the summer was equivalent to approximately 2800 international units (IU) of vitamin D a day, "which is a pretty big dose," Barger-Lux noted in an interview with Reuters Health.

Recommended daily doses of the vitamin are 200 IU per day for adults aged 19 to 50, 400 IU for those aged 51 to 70, and 600 IU for those over 70.

When the men were reassessed during February and March of the following year, vitamin D levels had fallen to less than 80 nanomoles per liter (nmol/L) in roughly half of the group. Vitamin D levels of at least 80 nmol/L are recommended to ensure optimal cellular health.

"We don't want to promote excessive sun exposure, but from the standpoint of making vitamin D naturally in the skin, we need to expose greater areas of the body for shorter periods of time--for example 15 minutes--because it's the first 15 minutes that does it," Bargert-Lux said.

Dietary sources of vitamin D are relatively limited and include fatty fish and fortified milk, while multivitamins tend to contain trivial amounts of vitamin D.

CBS The Early Show 11/27/02

As the days get shorter and winter approaches, most Americans will be soaking in fewer sun rays. But that's not necessarily a good thing, according to Consumer Reports on Health.

The body relies on the sun to get most of the vitamin D it needs to stay healthy. Ronni Sandroff, editor of Consumer Reports on Health, visited The Early Show to explain that its current issue reveals that many people suffer from Vitamin D deficiencies due to a lack of sun exposure, and that's a bigger problem than previously thought.

During the cold months of the year, Americans in the northern part of the country are most likely to have insufficient levels of vitamin D. They are getting less sunlight and what they are getting from the sun is not enough to help them. On average, people receive 90 percent of the vitamin D they need from sunlight and 10 percent from their diet.

Sandroff says people should get enough vitamin D by exposing themselves to the sun for 10 to 15 minutes a day without sunscreen during the warmer seasons of the year - depending upon how dark your skin is, how intense the sun is and the season. The winter sun is too weak to help. A recent study estimates that tens of thousands of Americans die each year of cancers possibly caused by too little sun exposure and too little vitamin D.

Vitamin D helps the body absorb calcium from food, which makes minerals available to the bones. Deficiency of vitamin D prevents new bone tissue from hardening, a condition known as rickets in children and osteomalacia in adults. It can also increase problems with osteoporosis in women. Moderate insufficient levels of vitamin D, can increase the risk of fractures.

Research studies have found that insufficient levels of vitamin D can also contribute to developing different types of cancer such as colon and prostate cancer, heart disease and diabetes.

Sandroff says the people at the greatest risk of having a vitamin D deficiency are people 65 or older, African-Americans and the obese.

Seniors tend to wear more protective clothing and stay indoors more than younger people, and their skin loses its ability to synthesize the vitamin. Also, older people are more likely to take laxatives and a cholesterol lowering drug called Questran, which interferes with the absorption of vitamin D. Questran is the only cholesterol-lowering drug that has been found to cause this problem.

African-Americans may suffer from vitamin D deficiency because of their problem of sun ray absorption. The darker the skin, the more sunlight is needed to generate vitamin D. A recent study from the Centers for Disease Control found that 40 percent of black women had insufficient levels of it.

Benefits of UV Light

Antibacterial -- The antibacterial qualities of the sun's rays and their exfoliating effect on the skin work to alleviate the effects of skin disorders such as acne, eczema and psoriasis.

Cholesterol Lowering -- Skin contains squalene, a chemical that is converted to cholesterol if it receives insufficient sunlight.

Lower Blood Pressure -- Studies have shown a correlation between lack of sunshine and increased blood pressure.

Cancer Prevention -- There is evidence that sunlight can help to prevent cancers of the breast, colon, prostate and ovaries, heart disease and multiple sclerosis

Former American Cancer Society Clinical Fellow Supervises Health Benefits and Sunshine Study by M. Janet Barger-Lux Senior Research Associate Office Address Osteoporosis Research Center Creighton University Medical Center 601 North 30th Street Omaha, NE 68131-2197 Office Phone: 280-4465 Fax: 280-5173

Reuters Health Story

Avoiding the sun is UNHEALTHY according to a CLINICAL FELLOW at the AMERICAN CANCER SOCIETY!!!!

Summer Sun Can't Sustain Vit. D Levels Year-Round Sept. 24, 2002

SAN ANTONIO (Reuters Health) - Counting on the sun alone for vitamin D will leave most people deprived of adequate amounts of this nutrient, especially during the winter in the northern parts of the US, researchers report. This is true even for people who work outside during the summer and get plenty of sun in the warmer months but not in the winter, according to study results presented here at the annual meeting of the American Society for Bone and Mineral Research.

For the study, Janet Barger-Lux, senior research associate, and Dr. Robert Heaney, both from Creighton University, Omaha, Nebraska, calculated the daily skin dose of vitamin D that 26 men who worked outdoors during the summer would have received. They brought the men back about 6 months later to assess how much vitamin D they may have lost over the winter. The team estimated that the amount of vitamin D that the group had received from the sun during the summer was equivalent to approximately 2800 international units (IU) of vitamin

Recommended daily doses of the vitamin are 200 IU per day for adults aged 19 to 50, 400 IU for those aged 51 to 70, and 600 IU for those over 70.

Dietary sources of vitamin D are relatively limited and include fatty fish and fortified milk, while multivitamins tend to contain trivial amounts of vitamin D.

Patient Education Information, National Institute of Mental Health, Clinical Psychobiology Branch, 1995

Research on seasonal affective disorder (SAD) and light therapy has been undertaken since the early 1980s. Since then, researchers in the United States, Europe and Japan have reported that light therapy improves the symptoms of SAD. Researchers at various centers have also found that light therapy may be helpful for other conditions including:

Non-seasonal depression
Delayed sleep phase syndrome (a condition in which people have difficulty falling asleep and waking up at conventional times
Premenstrual syndrome
Shift work and jet lag difficulties.

Contact:
Wolff System
sales@wolffsys.com
(800) 959-6533