SUNLIGHT and HEALTH *
How Sunlight Can Prevent Serious Health Problems
In ‘How to Live to 100+ Years free from Symptoms and Disease’ (refer homepage), the ‘Seven Requirements for Health’ (chapter 2, pages 19-23) are set out. Number 5 is ‘Sunshine’:
“The sun provides warmth and allows the plants and us to grow strong, vibrant and healthy. It gives us daylight. It produces vitamin D via the skin. It produces melatonin via the light entering the eye and stimulating the pineal gland. Studies have shown that proper (not excessive) exposure to the sun lowers blood pressure, reduces the resting heart-rate, balances the production of hormones, strengthens the immune system, lowers blood sugar and increases stress tolerance levels.”
This newsletter looks at the importance of sunlight for good health, as well as its role in helping to prevent, and helping in the management of, many common and often fatal diseases, for example, cancer.
The following table is taken from lifestylelaboratory.com. The article is by Richard Hobday and is based on his book ‘The Healing Sun. Sunlight and Health in the 21st Century’. (ISBN: 1-899171-97-5)
“Lack of sunlight and diseases related to it
Elevated blood pressure
Seasonal Affective Disorder
These diseases are thought to be linked to inadequate levels of vitamin D in the body, due in part to not enough exposure to the sun’s rays.
In many of the above disease states, the association with lack of vitamin D and sunlight has not been proven, largely due to the fact that, until quite recently, comparatively little research has been carried out into the effects of vitamin D on the immune system. I have referred briefly to this positive effect of vitamin D on the immune system in my June 2007 newsletter ‘The Immune System and Immunity’.
Vitamin D and its Relationship to Sunlight
Vitamin D is a group of fat-soluble prohormones (ie, no hormone activity in themselves), the two major forms of which are vitamin D2 (or ergocalciferol) and vitamin D3 (or cholecalciferol). These are converted to the active hormone 25-hydroxyvitaminD. The term ‘vitamin D’ also refers to metabolites and other analogues of these substances. Vitamin D3 is produced in skin exposed to sunlight, specifically ultraviolet B radiation.
Vitamin D’s role in the Body
Vitamin D plays an important role in the maintenance of organ systems:
- It regulates the calcium and phosphorus levels in the blood by promoting their absorption from food in the intestines and by promoting reabsorption of calcium in the kidneys, reducing its excretion.
- It promotes bone formation and mineralisation and is essential in the development of an intact and strong skeleton. It does this in concert with a number of other vitamins, minerals and hormones.
- It inhibits parathyroid hormone secretion from the parathyroid glands. Parathyroid hormone enhances the absorption of calcium in the intestines by increasing the production of the active form of vitamin D which affects the actual absorption of calcium (as Ca++ ions) by the intestine via calbindin. Thus there is a feed-back link between active vitamin D and parathyroid hormone, giving optimal absorption of calcium.
- It affects the immune system by promoting immuno-suppression, phagocytosis and anti-tumour activity.
Vitamin D Deficiency
Vitamin D deficiency can result from:
- inadequate intake
- inadequate sunlight exposure
- disorders that limit its absorption
- conditions that impair conversion of vitamin D into active metabolites, such as liver or kidney disorders
Vitamin D deficiency:
- results in impaired bone mineralisation, that leads to bone softening disease, rickets in children and osteomalacia in adults, and contributes to osteoporosis.
- may also be linked to many forms of cancer and other disease states.
What are the Sources of Vitamin D, Calciferol?
- Fortified food sources.
Very few foods are naturally rich in Vitamin D. Fortified foods are the major dietary sources of vitamin D, and these include milk, soy milk, cereal grains, margarine, bread and pastries. It is important for individuals with limited sun exposure (from whatever cause or for whatever reason) to include a food source of vitamin D in their diet.
In Australia, there is mandatory fortification of table edible oil spreads (eg low-fat spreads) and table margarine, and voluntary fortification of modified and skim milks, powdered milk, yoghurts, table confections and cheese.
- Natural sources of vitamin D include:
- Fish liver oils such as cod liver oil. 15ml cod liver oil provides 1360iu of vitamin D
- Fish such as salmon, mackerel and sardines. 100 gm salmon provides 360iu of vitamin D, 100gm mackerel provides 345iu and 50gm sardines provides 250iu
- Egg. One whole egg provides 20iu of vitamin D
- Shiitake mushroom, a vegetarian source of vitamin D.
This is the ideal source of vitamin D. The best place to get vitamin D is from your skin!
When your skin is exposed to the Ultraviolet B (UV-B), present in normal sunlight, vitamin D is formed or synthesised from cholesterol and acts as a pro-hormone, rapidly converting into 25-hydroxyvitamin D. Experts agree that NO harm results from the vitamin D concentrations produced by sun exposure and that such levels are probably optimal for human health.
Ultraviolet light is divided into 3 bands UV-A, UV-B and UV-C.
UV-B, also called the “burning ray”, is the primary cause of sunburn, caused by over exposure to sunlight. However UV-B stimulates the synthesis of vitamin D in the skin.
The amount of UV-B reaching the skin depends on:
- exposure time
- latitude and altitude of location
- the amount of skin surface exposed
The following also affect the amount of UV-B that reaches the skin:
- window glass, which allows only 5 percent of UV-B to get into your home, office or automobile
- clouds, which may block UV-B
- pollution (smog and ozone), which partially blocks UV-B
- use of sunscreens.
It is important to stress that you should never get sunburned. At the most, the skin should only turn a very light pink, ie mild erythema. Implement sun exposure very gradually. Sunburn is related to an increased risk of skin cancer.
Interestingly, if you avoid getting sunburned and actually have regular sun exposure, you will have a decreased risk of the dangerous skin cancer, melanoma.
We are all designed to have regular sun exposure, the exception being those with the genetic disorder of albinism. Those with fairer complexions, red hair etc, require less exposure before mild erythema develops, compared to those of darker complexion, or compared to those who have developed tanning from regular sun exposure.
Sunlight, as long as you avoid exposure that will cause burning, will help improve your health.
Remember: Don’t ever get sunburned.
Fair skinned individuals need far less exposure to receive their dose of sun to produce vitamin D. Lighter skin allows for greater penetration of UV-B, leading to higher levels of vitamin D. The more pigmented, natural or sun-induced, the less the penetration of UV-B and hence greater exposure is needed. Elderly individuals have less enzyme in their skin, from degenerative aging, and so the skin has a limited capacity to form vitamin D.
It is impossible to get vitamin D toxicity from too much sun exposure.
UV light exposure beyond the minimal dose to produce skin redness (erythema) does not increase the production of vitamin D any further.
It is commonly thought that only occasional exposure of the face and hands to sunlight is ‘sufficient’ for vitamin D nutrition. This is NOT so, especially in winter or in higher latitudes and/or higher altitudes.
Testing Levels of Vitamin D
The correct test is the blood level of 25-hydroxyvitamin D. Normal values are 20-56 ng/ml or 50-140 nmol/L.
Recent clinical research suggests that the level should be equal to, or greater than, 45 ng/mol or 115 nmol/L. This research states:
“Your vitamin D level should NEVER be below 32 ng/ml. Any levels below 20 ng/ml are considered serious deficiency states and will increase your risk of breast and prostate cancer and autoimmune diseases like multiple sclerosis and rheumatoid arthritis.”
It should be noted that vitamin D is a fat soluble vitamin and can be quite toxic. Once you have vitamin D toxicity, you cannot easily reverse it. Take care if you self medicate. If in doubt, consult a trained health care professional.
Vitamin D Supplements
If supplementation of vitamin D is necessary, due to lack of adequate exposure to sunlight, cod liver oil is the best choice. Eating fish is not enough.
Cod liver oil also contains vitamin K, which is an essential co-factor in building strong bones. Natural vitamin A is also in cod liver oil and this supports the immune system. The oil is also full of the important essential fatty acid omega-3. There is a protective benefit of vitamin A in limiting high calcium levels from vitamin D.
Cod liver oil need not be taken as a source of vitamin D if adequate sun exposure takes place.
Over 25 years ago, in 1981, what is said to be one of the most successful advertising campaigns in Australia’s history was launched.
“Slip, Slop, Slap!
Slip on a shirt, slop on sunscreen and slap on a hat
Slip, Slop, Slap!
You can stop skin cancer - say: Slip, Slop, Slap!”
The text/sms message re the weather, from the Bureau of Meteorology, starts with “SunSmart UV Alert”. A UV index less than 3 means there is no alert. The higher the index above 3, the higher the alert.
Sunscreens with a sun protection factor of 8 or greater will block UV-B rays that produce vitamin D in the skin.
How Safe are Sunscreens?
The main chemical used in sun lotions to filter out ultraviolet light may be toxic, particularly when exposed to sunshine.
Octyl methoxycinnamate (OMC), present in the majority of sunscreen brands, was found to kill mouse cells even in low doses, in a study by Norwegian scientists. The findings, reported in ‘New Scientist’ magazine, suggest that human cells could be damaged if a sunscreen containing OMC penetrates the outer layer of dead skin and comes into contact with living tissue.
It is recommended by the research team that sunscreens should be treated with caution and used ONLY when it is impractical to stay indoors or to shield the skin from sun with clothes, in order to prevent sunburn.
It was also shown that OMC, when exposed to sunlight, was twice as toxic as the chemical alone.
Skin Cancer and Melanoma
The purpose of avoiding exposure to sunlight – slip, slop, slap - is to prevent, or at least reduce, the incidence of skin cancer, in particular, melanoma. The link between UV radiation and skin cancer has been repeatedly demonstrated.
Since, as we have seen, exposure to sunlight, in a controlled and sensible way, is essential for health via vitamin D, is there another aspect of the aetiology of skin cancers and melanoma that should be considered?
Epidemiological and animal-based investigations have indicated that the development of skin cancer is, in part, associated with poor dietary practices.
Lipid content, and subsequently the derived fatty acid composition of the diet, are believed to play a major role in the tumorigenesis (development of cancer).
Omega-3 fatty acids (including docosohexaenoic acid, DHA, and eicosapentaenoic acid, EPA) can effectively reduce the risk of skin cancer, whereas omega-6 fatty acids (such as arachidonic acid, AA) reportedly promote the risk of skin cancer.
- In the normal diet, the ratio of omega-3 to omega-6 is in the region of 1: 20-30 (or higher)
- Ideally, the ratio should be 1:1. When the ratio is 1:1, the risk of sun-induced skin cancer is minimal and it is ideal for overall health
- An Australian study, some 15 years ago, showed a 40 percent reduction in melanoma for those who ate omega-3 rich fish.
Consuming a diet high in antioxidants, especially vitamin C (from fresh fruits and vegetables), will increase antioxidant levels in the body, which will also provide protection against sun-induced radiation damage. For more information on this topic, refer to my January 2007 newsletter ‘Free Radicals – Antioxidants’.
Dr Joseph Mercola (mercola.com, June 19, 2007) wrote the following:
“How many people know that not getting enough sun KILLS 50,000 people from cancer deaths every year in the U.S alone?”
“The myth that the sun is detrimental to your health and that sunscreen is a necessity to guard against cancer is one of the most pervasive hoaxes in our society today”.
“This myth can be traced back to two industries that benefit the most: the cancer industry and the sunscreen manufacturers …… These two giant profit-makers tag-team efforts which keep the unsuspecting public in a trance”.
“Studies have shown that vitamin D can prevent as many as 77 percent of all cancers.”
Lack of Sunlight and Diseases Related to Lack of Sunlight
At the beginning of this newsletter, I listed a series of diseases believed to be caused by lack of sunlight.
These diseases are thought by some researchers to be linked to inadequate levels of vitamin D in the body.
Comparatively little research has been carried out into the effects of vitamin D on the Immune System.
Also, vitamin D status in the general population is not routinely measured.
Vitamin D Deficiency
The following illustrates how deprivation of sunlight causes vitamin D deficiency.
It is a study of young men, on normal diets, who were deprived of sunlight by being kept indoors at the Royal Navy’s Institute of Naval Medicine. Within six weeks, their vitamin D stores had fallen sufficiently to cause inadequate absorption of calcium and a negative calcium balance (ie, more calcium was lost than was retained by the body). After two months of this regime (deprivation of sunlight), their vitamin D levels had fallen by half, and they had begun to lose calcium at a faster rate than they could retain/absorb it. By the tenth week, there was a shortfall of one third in the calcium (retained by the body) needed to maintain a healthy balance.
Thus the prospects for adequate vitamin D levels in the body, for anyone on a normal diet, who is house-bound or institutionalised, are not favourable if they are unable to get out in the sun.
The ‘slip, slop, slap’ approach deprives those who follow such (strongly) recommended precaution against the dangers of sunlight from the benefits of vitamin D produced in the skin by the UV of sunlight.
Don’t forget that the use of sunscreen with a sun protection factor (SPF) of 8 or greater inhibits more than 95 percent of vitamin D production in the skin. To avoid vitamin D deficiency, some dermatologists recommend supplementation of vitamin D along with sunscreen use.
Fifty years ago, rickets was virtually unheard of in Australia – babies were put out in the sun for ‘sun kicks’ and, as youngsters, they routinely played outside. Not so now, and cases of rickets are now being seen.
Vitamin D requirements increase with age, thus the elderly are more prone to vitamin D deficiency.
Obese individuals may have lower levels of the circulating forms of vitamin D, probably due to reduced bioavailability, and are at higher risk of deficiency.
Melanin acts like a sun-block, prolonging the time to generate vitamin D. Thus dark-skinned individuals (whether genetic or due to tanning), need longer exposure to sunlight, especially at higher altitudes.
Vitamin D and Immuno-modulation
Vitamin D is an important nutrient to optimise immune function.
The hormonally active form of vitamin D mediates immunological effects by binding to nuclear vitamin D receptors (VDR) which are present in most types of immune cells.
Activation of the VDR has potential anti-proliferative, pro-differentiative, and immuno-modulatory functions including both immuno-enhancing and immuno-suppressive effects.
The complexity of the immune system has been discussed in my June 2007 newsletter ‘The Immune system and Immunity’. Detailed discussion and references related to vitamin D’s role in immuno-modulation can be found in wikipedia.org/wiki/vitamin_D.
This role of vitamin D on the Immune System is linked to the benefit of sunlight in such conditions as infections (especially tuberculosis), multiple sclerosis and many cancers.
THE DISEASES RELATED TO LACK OF SUNLIGHT
As already mentioned, these diseases are thought to be linked to inadequate levels of vitamin D in the body, as a result of reduced exposure to sunlight and UV rays. The following discusses these in more detail.
- Rickets and Osteomalacia
These are sometimes referred to as the ‘Diseases of Darkness’.
Children with rickets suffer from bone deformities and muscle weakness. Their bones soften, with the result that there is an outward curvature of their legs and a curvature of the spine. Their teeth are late coming through and often fall out.
This softening, weakening and demineralisation of the bones can also affect adults, in whom the condition is referred to as osteomalacia.
Sunlight cures and prevents both rickets (children) and osteomalacia (adults). These are diseases of darkness and not diseases of diet.
Traditionally, sunlight deprivation has been linked to weak and brittle bones.
The bone disease osteoporosis is becoming so common in Western countries as to be termed a ‘silent epidemic’.
Figures from the United Kingdom, to cite one Western country, show that one in three women over 50 years and one in twelve men over 50 years have osteoporosis. Each year 50,000 wrist fractures, 40,000 vertebral fractures and 60,000 hip fractures are diagnosed. Low levels of vitamin D are implicated.
The subject of osteoporosis has been addressed in detail in ‘How to Live to 100+ Years Free from Symptoms and Disease,’ (see homepage), chapter 10 ‘Dairy Products, Osteoporosis and Calcium’. It results from a negative calcium balance and there are multiple factors involved in this, including a diet rich in acid-forming foods, as well as a lack of vitamin D.
It should be noted here that conventional medical thinking holds that lack of sunlight does not play a major role in the genesis of this disease. However, there is a pronounced seasonal variation both in bone density and in the incidence of hip fractures, especially in the northern hemisphere. Bone density is at its lowest in winter, more hip fractures occur in the winter months than at other times in the year and hip fractures become more common with increasing latitude. Most falls and fall-related injuries take place in the home, so this seasonal variation in fractures is not due to ice and snow caused falls.
Sunlight can help prevent tuberculosis (TB) from developing, in susceptible individuals, by keeping up their vitamin D levels. Vitamin D metabolism leads to the activation of macrophages and restricts the intracellular growth of mycobacterium tuberculosis, the cause of TB.
Sunlight can also prevent the disease spreading in dwellings, by killing the mycobacterium.
This is why there has been such close association between sunlight and TB in the past. The beneficial effects of sunlight, on TB patients as therapy, were widely recognised in the early years of the 20th century, in the pre-antibiotic days. Sunlight therapy was used to prevent people, who were susceptible to the disease, from developing it.
In the 1950s, drugs such as streptomycin became available and TB was no longer the threat to public health it had once been. But 50 years after the introduction of streptomycin, TB is still responsible for more deaths worldwide than any other single infectious disease!
- Multiple Sclerosis
A recent study (2006), published in The Journal of the American Medical Association, reported evidence of a link between vitamin D deficiency and the onset of multiple sclerosis, an auto-immune disorder. The authors posit that this is due to the immune-response suppression properties of vitamin D. It is known that the incidence of multiple sclerosis increases dramatically with the increase in latitude (especially northern hemisphere) and that exposure to sunlight in childhood and adolescence protects against the disease in later life. Will ‘slip, slop, slap’ lead to an epidemic of multiple sclerosis in the future?
Apart from the role of vitamin D in immune modulation, some believe that the sun’s role, in preventing multiple sclerosis, is that getting sunlight into the eyes affects the immune response of the central nervous system in some, as yet, unexplained way. Sunlight may inhibit the development of ‘optic neuritis’, which affects about 85 percent of people who then go on to develop multiple sclerosis.
These are good grounds for discouraging children from wearing sunglasses as well as encouraging regular, moderate sun exposure. Yet despite this, in recent years, the ‘slip, slop, slap’ slogan has been extended to: ‘Slip on a shirt, slop on the sunscreen, slap on a hat, wraparound the sunglasses’.
Adequate vitamin D levels are an essential in the treatment of multiple sclerosis, and may be difficult to achieve and maintain in those who suffer from multiple sclerosis.
- Other Autoimmune Disorders
Sjogren’s syndrome, rheumatoid arthritis, thyroiditis and Chron’s disease have all been linked with low vitamin D levels.
- Heart Disease
Coronary heart disease is the Western world’s number one killer, almost displaced from this position by cancer. Genetics, poor diet, excessive weight, high blood pressure, high cholesterol, lack of exercise and smoking are all risk factors in heart disease. Sunlight lowers blood pressure and cholesterol levels (see below) and improves cardiac output.
The highest incidence of heart disease in the UK is amongst the less well-off families in Scotland, Northern Ireland and the northwest of England. In a study published in the ‘Quarterly Journal of Medicine’ in 1996, sunlight deprivation was identified as a potential risk factor. Bad housing, minimal participation in outdoor physical activities such as gardening, and insufficient money for holidays in sunny places were cited as reasons for lack of sunlight exposure amongst this high risk group.
Northern countries (higher latitudes) have higher levels of heart disease, and more heart attacks occur in the winter months.
Again, around the world, the further you are from the equator, the more likely you are to find people with high blood pressure or hypertension. This new theory suggests that the relative lack of sunlight, and hence the reduced levels of ultraviolet light, may actually contribute to the rise in blood pressure at higher latitudes, and also explains why black-skinned people in the USA and Europe have a greater risk of high blood pressure than white-skinned people in these countries. The greater the pigmentation in the skin, the more UV-B light is required to produce the same amount of vitamin D as in those with less-pigmented-skin (ie lighter skin).
- Blood Cholesterol
Blood cholesterol levels also increase with distance from the equator. The mechanism for this is unclear, but it is suggestive that the relative lack of sunlight, with the resultant lower levels of vitamin D, contributes to the higher levels of cholesterol. Vitamin D is made from cholesterol in the skin, stimulated by UV light.
Vitamin D deficiency has been associated with insulin deficiency and insulin resistance.
Type 1 diabetes, insulin dependent and most common in childhood (Juvenile diabetes), is an autoimmune disease and, as we have seen, vitamin D is important for optimal immune function.
Type 2, adult-onset diabetes, is also a multi-causal condition, especially linked to lifestyle – overweight, poor diet and lack of exercise.
It is known that sunlight has a similar effect to insulin, in that it lowers the concentration of glucose in the blood. Although this is not particularly noticeable in normal individuals, the effect can be dramatic in diabetics.
This is a benign, but chronic, inflammatory skin condition. Sunlight therapy is particularly effective in its management.
- Tooth Decay
There are no recent studies on the relationship between sunlight and tooth decay. However, for example, an American study in 1939, of 94,000 white males aged between 12 and 14, showed a clear correlation between sunlight and tooth decay. Those who lived in the northwest of the USA, where the mean annual sunlight was less than 2,200 hours per year, had two thirds more cavities than their compatriots who lived in the southwest of the country and received more than 3,000 hours of sunshine per year.
- Seasonal Affective Disorder and Depression
Seasonal Affective Disorder is the occurrence of higher levels of depression and mood change that occur during winter, with the relative lack of sunlight. Especially does it occur in higher latitudes with the very cold winters and very little sunlight.
Sunshine (and indeed bright light) prevents the Seasonal Affective Disorder, as it suppresses the secretion of the neuro-hormone melatonin, and hence strengthens the immune system.
Activated vitamin D in the adrenal gland regulates the enzyme tyrosine hydroxylase, the rate limiting enzyme necessary for the production of the neurotransmitters dopamine, epinephrine and norepinephrine.
The Seasonally Affective Disorder has been treated successfully with vitamin D.
Today it is well established that, besides playing a crucial role in the establishment and maintenance of calcium in the body, the active form of vitamin D calcitrol also acts as an effective regulator of cell growth and differentiation in a number of different cell types, including cancer cells.
Laboratory, animal and epidemiological evidence suggests that vitamin D may be protective against some cancers. It has been found to induce death of cancer cells, both in vitro (in the laboratory) and in vivo (in the body). Although the anti-cancer activity of vitamin D is not fully understood, it is thought that these effects are mediated through vitamin D receptors expressed in cancer cells, and may be related to its immuno-modulatory abilities.
Clinical studies now show vitamin D deficiency to be associated with some of the most common cancers, including breast, prostate and colorectal.
In the journal ‘Cancer’ (March 2002), Dr William Grant published the results of an examination of 506 regions in the USA. He found that was a “close inverse correlation between cancer mortality and levels of ultraviolet B light”. That is, he found that the less sunlight, the greater number of cancers. The likeliest mechanism, for a protective effect of sunlight, is vitamin D.
There are 13 cancers that showed this inverse correlation, mostly reproductive and digestive cancers. The strongest inverse correlation is with breast, colon, prostate and ovarian cancers. Other cancers apparently affected by sunlight include cancer of the bladder, uterus, oesophagus, rectum and stomach.
The latest article on the benefits of sunlight and vitamin D in preventing cancer was published in August 2007, in ‘Nutrition Reviews’ (volume 65). It comes from researchers at the Moores Cancer Center, University of California, San Diego. Dr Cedric F. Garland says:
“For the first time, we are saying that 600,000 cases of breast and colorectal cancer could be prevented each year, worldwide” ….. by adequate intake of vitamin D……. “This could be best achieved by a combination of diet, supplements and short intervals in the sun”.
The findings of epidemiological studies of sunlight and cancer are supported by work in the laboratory. Much of this data is reviewed by Dr Richard Hobday in ‘How Sunlight Can Prevent Serious Health Problems’. (See lifstylelaboratory.com/ articles/hobday/sunlight-prevent-problems.html).
Does this mean that one’s sun exposure does not contribute to skin cancer?
However, skin cancers, as already mentioned, are more likely to be related to the large distortion most people have in their omega-6 to omega-3 fatty acid ratio. While this ratio should ideally approach 1:1, it is often 30 (or greater):1. This high excess of omega-6 fats in most people’s diets puts them at much higher risk of developing skin cancer when exposed to excess sun.
It is sunBURN, in conjunction with excess omega-6 fats, that increases your risk of skin cancer.
But even with the potential increase in skin cancer, most skin cancers are relatively benign when compared to breast, colon and prostate cancers.
It is claimed by some authors that, for every one skin cancer (especially melanoma) prevented by avoidance of sun exposure (‘slip, slop, slap’), 10 or more (even up to 50) other cancers are caused by the sunlight deprivation.
So, why not change the fat content of your diet and use sensible sun exposure to reap the benefits of sunlight?
With exposure to sunlight, ultraviolet B radiation from the sun converts cholesterol to vitamin D, one of the most potent anti-cancer vitamins, as well as being an important factor in the prevention of the diseases related to lack of sunlight.
The best and safest way to get vitamin D is from the sun.
The safe way is to be out in the sun so that the skin turns a very light pink. Do not get sunburned, that is over exposure. Be careful about using sun-blocks. A sun protection factor of 8 or greater blocks out 95% of ultraviolet-B. Some are also dangerous in their own right, due to toxic chemicals that enter the blood stream via the skin.
In spite of the above, in November 2007, the NSW government has embarked upon a further intensive promotion of ‘Slip, Slop, Slap’, at a cost of $11,500,000.
Have a healthy, careful, appropriate relationship with sunlight.
* Copyright 2007: The Huntly Centre.
Back to the list Print friendly version