🚀 go-pugleaf

Hilary Lane <hilary@dash.com> wrote:

>  I heard that in Australia, it is mandatory for school children to
>  wear hats that shield their face from the sun...and also
>  shield the back of their neck because Australia has the highest 
>  percentage of skin cancer in the world. I'm unclear why, maybe 
>  because of CFCs, but maybe someone can shed some light here. 
>  I live in the US, so I don't know much about this issue.

I will try to shed some light of the non-UV variety.

As a general rule, the amount of UV reaching the earth's surface from
the sun is a function of how far the light has to travel through the
atmosphere to reach the earth's surface.

The higher up a mountain you go, the less atmosphere above you, and
the more UV reaching you. 

This is a reason why skiers have to take precautions against sunburn,
although they are tending to get a double dose from UV which is
reflected in a diffuse fashion off the snow and which adds to the UV
which hits them directly from the sun

(The diffuse reflection means that it is coming from all angles, and
so there are fewer shadow areas of your skin in shadow, and the
overall exposure is increased).

Averaged on a yearly basis, the light reaching the earth's surface
near the equator takes a much shorter path through the atmosphere then
it does outside the tropics.

This simply means that on the average, the sun is directly overhead
near the equator, and so light travels a shorter distance through the
atmosphere than it does at higher latitudes. (ie., more to the north
or south).

So, the average amount of light hitting the earth is at its greatest
at the equator, and gets progressively less as you go towards the
Poles.

The rule is, the lower the latitude (the closer you get to the
Equator), the greater the UV. This prediction has been thoroughly
tested, and found to be true.

I am not a dermatologist, so here goes: 

Skin cancers divide into 2 distinct types, non-malignant carcinomas,
and malignant melanomas.

The skin carcinoma to which you are referring are caused by long term
exposure to ultra violet light, specifically the medium wavelength 
UV B, which is topical <no puns intended> in discussions about ozone
depletion.

The relation between the incidence of skin carcinomas and exposure to
UV is clear cut. The mechanisms involved are well know, the
biochemical changes caused by UV B exposure, and leading to the
formation of carcinomas have been thoroughly researched.

(One out of numerous references is: "Unravelling the Molecular Pathway
from Sunlight to Skin Cancer",  J.S. Taylor, Acc. Chem. Res vol 27,
pp76-82, 1994).

There is a close correlation between the incidence of skin carcinomas
and latitude. The closer to the equator, the higher the incidence of
carcinomas.

The picture isn't quite as simple as that as racial differences,
health standards, diagnostic standards, life styles, and many other
population demographics can mask trends across different countries.

Two countries in which these differences do not generally apply, and
which are large on the North - South axis are the USA and Australia..

In both these countries there is a close correlation between the
incidence of skin carcinomas and latitude. The further south you go in
the USA, the higher incidence of skin carcinomas. The rate of deaths
from skin cancers in Florida is twice that of Wisconsin. In Australia,
the further you go North, the higher the incidence of cancer.

The malignant melanomas are not so clear cut in their relation to UV
exposure It appears that they are caused by short periods of intense
exposure (eg., severe sun burn), mixed with long term moderate
exposure.

The main factor seems to be the intense short exposures. As malanomas
can take a number of decades to appear, it is difficult to determine
their causes. UV A, the form which is not blocked by ozone or sun
screens, and is generally regarded as safe in comparison to the high
energy B variety, also seems to be implicated in the formation of
melanomas.

One thing is well known, the same correlation between latitude and
incidence as occurs for skin carcinomas, also occurs for melanomas,
and general opinion is that UV exposure is the primary cause of
melanomas.

Australia has the highest incidence of skin cancer in the world, and
Queensland is the state with the highest incidence.

Why here?

Well might you ask.

Start by looking at a map of the world and see what other countries of
similar or lower latitudes are affluent, essentially white middle
class, with high public health and medical standards, and much outdoor
leisure and work activity. 

Add to that that no other country can boast the thousands of miles of
beautiful sandy beaches that this country has, and you are starting to
get a picture.

White?

The country was invaded (settled) by predominantly English and Irish
people until post WW2 immigration from other countries dramatically
changed, mainly as a consequence of government policies.

I cannot speak for the Irish, but Noel Coward spoke for the English in
his song, "Mad Dogs and Englishmen" (go out in the midday sun).

This is absolutely true, and it is the shear arrogance and stupidity
of the European invaders that they thought that they knew more than
the accumulated knowledge and wisdom of the people who had lived here
for about 40,000 years. 

In general, the aboriginals avoided going out in the Summer sun
between about 10 am, and 2 pm.

---------------------[Editorialising]------------------------------

These white industrial nomads, divorced from their social, cultural
and ancestral roots, and divorced from their roots in Nature, adopted
the "pioneering spirit", which is a way of life based on the principal
"if it moves, shoot it, if it stands still, chop it down".

Driven by an essentially protestant work ethic, and an imperative to
consume, be silent, and die, these primitive environmental thugs did
not have time to reflect on the higher things of life, and such
matters as why it is that they had to work twice as long in a
competive and hostile social environment, as their black brothers and
sisters did for their daily bread.

They did not stop to think that these people might be more evolved
than they, and that arbitrarily describing them as `primitive' may
have been a knee jerk reponse to the distasteful subconscious
realisation that the aboriginal genetic code is more modern than the
European.

I can hardly wait for the flames.

---------------------[ End of Editorialising]---------------------

Just the same, middle class afluence generally means lots of leisure,
and the immediate motivation was to escape from those cloistered walls
representing millenia of senescent European conditioning <stirring!>
and head for that very large tract of country known as "the Great
Outdoors".

So it is that we have tended to live one of those healthy outdoors
life styles which would be even healthier if it were not for skin
cancer, sharks, crocodiles, spiders, snakes, blue ringed octopusses,
mosquitos, stone fish, box jelly fish, bunyips, feral animals, feral
kids, and the tax man.

White people do seem to have a greater predisposition towards skin
cancer than black, although this has been disputed, and there are many
other factors which make the issues far less clear cut, for instance:

-  High mortality rates in poor countries can mean that people die of
   causes other than skin cancer, or before skin cancers have had time
   to develop.

-  Poor public health standards and limited access to medical
    facilities, can result in low attendences at clinics, and failures
    to correctly diagnose skin cancers.

-  Poor public health facilities usually go hand in hand with poor
    public record keeping and reporting, leading to inaacurate
   estimates of incidence.

-  White people are not indigenous to tropical regions, and so do not
    have a cultural tradition and lifestyle adapted to tropical
    life, eg.,  siestas. This may lead to increased exposure.

Despite the factors, the majority opinion of researchers seems to be
that a white skin puts one at a greater risk of getting skin cancer. 

It should be noted that being black, while seeming to afford some
degree of protection, falls far short of offering complete protection,
and has its own dangers.

A black skin tends to mask the slight reddening which attends slightly
excessive exposure, which results in irritation rather than pain. The
lack of the extra warning sign of reddening may result in failing to
stop or lessen exposure.

Far worse, the blemishes on the skin which are the early telltale
signs of cancer, are much harder to detect on a black skin.
 
So the reasons why Australia has a high incidence of skin cancer is
due to many factors, latitude, a mainly white population, increased
leisure resulting in increased exposure, better public health leading
to proper diagnosis, proper public record keeping leading to accurate
statistics, the lack of social traditions which minimise the risk of
excessive exposure, and long life expectancy giving cancers the
opportunity to develop. These, and other factors would all play a
part.

Our beaches are very attractive, and if you watch the next Olympics,
make a note of the performance of the Australians in the swimming
pool, look at the medal tallies, and divide by the populations of the
respective countries, and you will see how popular water sports are in
this country, as they have been for so long. 

(Actually I lie. The real reason why Australia is ranked so high in
international swimming is because the few who are foolhardy enough to
enter the water, learn to swim faster than the sharks and the
crocodiles.Through a process of natural selection, there is now a gene
for fast swimming in our gene pool. As for what is left in the pool
after the crocs have been there...

When our swimmers race in the Olympics and hear the crowd cheering,
they think it is the New Zealanders cheering on the sharks and the
crocodiles, and so swim exceptionally quickly. :-)

While the fact that Queensland is one of our three most northern
states is the reason why it has a higher incidence of skin cancer than
the southern states, why it should have a higher incidence than the
other two northern states is a mystery to me, and which I will let
others try to solve. 

One thing is for sure, that swimming is definitely out in some regions
because you are not going to live long if you try, and lieing around
on the bank a few metres from the edge of a river is a sure way of
having something a lot bigger than you, displace you from your secure
position at the top of the food chain.

I doubt that this is a factor, but Queensland's world famous beaches
with their white sands reflecting UV, may be a factor. Sun baking on
the beach has been a popular past time for many, although people are
taking tending to take considerable precautions in protecting
themselves as a consequence of the massive public education on the
skin cancer, and which I will discuss below.

I find it ironic that a percentage of that fortunately small number of
racists, should spend so much time trying to become the same colour as
the people they despise.

Interestingly, there has been a gender distribution in skin cancer
here. Men have had a greater tendency to get skin cancer on the right
arm, and women on the left. 

This says a lot about this society. 

In case you haven't worked out what is happening, remember that,
unlike the USA, we drive on the correct side of the road in Australia.
<hehehe>

For those who still haven't worked it out yet, here in civilisation
we drive on the left side of the road. 

Men have traditionally tended to drive more than women, hence
the greater incidence of skin cancer on the right arms of men, and as
women have tended to occupy the left front passenger seat they have
had a higher incidence of skin cancer on their left arms.

This situation may change in the future, for there is a growing number
of women getting black belts in mechanics. Somehow I just know I am
going to get flamed.

So, what are we doing about skin cancer?

Given the magnitude of the problem here, it is natural that Australia 
should be at the top in skin cancer research. 

Queensland, has had the advantage of being home to what has been
described as one of the 7 great wonders of the natural world, the
Great Barrier Reef, one of the most complex ecosystems on the planet.
 
I guess the Almighty gave that to Queenslanders to compensate for the
fact that the southern states were going to refer to Queensland as
"our deep north", and make jokes such as: "Why do Queenslanders call
their beer xxxx?", Answer: "Because they can't spell beer".

<I just know I am going to get flamed>

Researchers investigating the colour changes in coral in response to
light discovered an interesting chemical. It is inevitable that
somebody got the bright idea of using this in UV sun screens. It is
the best so far.

Education is an important part of public health, and so there has been
extensive education about becoming "sun smart" <great phrase, key to
sucess> in the schools, and on television and radio.

Part of this advertising has been the "Slip, Slop, Slap", campaign,
which I think translates into slipping into clothes which will protect
you from the sun, slopping on some sun screen on the face and any
other exposed parts, and slapping on a hat. 

It is this type of easy to remember formula which seems to form the
basis of many a sucessful public health education campaign, and it has
been *very* effective.

We don't get pollution and smog warnings here, but we do get UV
reports and predicted risk levels with the weather reports in Summer,
and there have occasionally been special UV warnings.

There are positive spin offs to all of this. A couple of sun smart
teenagers got "big business smart". They got sick of the boring old
white zinc cream, and added food colouring to it. Their friends wanted
it, and eventually they started selling it. 

Then they set up a company, got the stuff passed by the FDA in the
USA, and now they are millionaires.

It has been found that most of the damage leading to skin cancer tends
to occur in childhood. This is probably because kids spend a lot of
time terrorising the local wildlife outdoors as a by product of their
exhuberance.

Attempts were made to harness some of this energy pool with bicycle
powered generators, but people realised that an even better energy
source is the hot air coming from politicians. There is an alternative
view that we could solve the world food shortage if we ate all the
politicians. Politicians are now learning to run very quickly. 

I am trying to make a lightweight solar powered microwave for when we
catch them.

Besides education in schools, there has been a burst of intense effort
on the part of schools and councils to cover play areas in
kindergartens, and provide play areas in public parks and schools with
much better shelter, especially above play equipment.

The cynical may regard this as simply a response to the realisation
that many years down the track, some person who develops skin cancer
may sue schools and councils for failing to exercise their duty of
proper care. Certainly such a possiblity may serve to motivate
institutions reluctant to act.

Is ozone depletion responsible for the high incidence of skin cancer
here? 

In one word, no.

This is the majority opinion of researchers and specialists in the
field, although there is a minority of dissenters. Average global
ozone depletion is only 3% per decade, and if it is a recent
phenomenon, as the majority of research and opinions in the field
would have one believe, then the phenomenon has not been around long
enough for it to reflect in an increase in the incidence of skin
cancer, for skin cancers generally take at least a decade to appear,
and up to 3 decades.

A few years ago when the Antarctic hole broke up mixing with air from
the mid latitudes, part of this diluted hole drifted over the southern
part of Australia, reducing ozone levels by 10%, with a corresponding
increase in UV B penetration. 

In the Spring of 1994, the tip of South America suffered a spectacular
drop in ozone levels of 45%, with a sharp and large increase in UV
penetration.

Worried? You shouldn't be. All that meant was that UV B penetration
ended up as low as that in Buenos Aries in mid summer. 

At no point has the level of UV B penetration in mid latitudes reached
the level of penetration in summer in the tropics.

But it is my opinion that if the Montreal Protocol were not in place,
and we had continued releasing CFCs at the rate we were, then at some
point down the track we would have a lot more to worry about than skin
cancer.

I am not necessarily referring to cataract and retina damage.

Nor am I referring to eye damage in the cattle and other animals on
which we depend.

I am not necessarily worried about a probable drop in amphibian
populations, although that could be a worry given that frogs help keep
insects under control.

I am not necessarily worried about eye damage to birds which also help
control insect populations.

I am not necessarily worried that many plant species can be adversely
effected by increased UV levels.

I am not necessarily worried that the effects on marine micro
organisms could cause UV tolerant strains to dominate, critically
altering the balance so that the whole marine food chain was
jeopardised.

I am perhaps more worried that by lowering marine phytoplankton
productivity on a global scale, and altering the species balance, we
could end up with a disastrous drop in global phytoplankton population
levels which would seriously diminsh the ocean's ability to sink CO2
from the atmosphere, and hence accelerate global climate change
resulting from greenhouse emissions.

I guess that I would be most worried that we would change the whole
balance of pollinating and predating insects, and possibly place in
jeopardy the 5 species of grain responsible for about 90% of world
food production.

Basically, nobody knows what would have happened.

Most of the theories about CFC induced ozone depletion were in place a
decade before the hole was discovered. Ozone depletion was predicted,
but the level was expected to become problematic in a century or two.

Then the hole was discovered.

Subsequent research modified the original theories to some extent,
without changing their fundamental nature.

CFCs are composed of chlorine, fluorine, carbon, and hydrogen.

In just one decade there was a doubling of an important chlorine
compound implicated in ozone depletion in the stratosphere over
Antarctica, and a tripling of its fluorine equivalent. 

The ratio of fluorine to chlorine jumped 50% in 7 years. This change
strongly suggests that natural sources were not the cause, and a 60%
increase in a breakdown product which can only come from CFCs,
occurred over the same period.

This is enough to make scientists switch on the red lights and warning
bells. 

There are those who argue that natural sources of chlorine are the
problem, and not CFCs. 

They like to argue about conspiracies and this sort of thing. I am not
cynical enough to suggest that the large chemical companies are paying
them to kick up a stink, but I am cynical enough to point out that
there are those who still believe that the earth is flat, and another
mob of nutters who think that we live on the inside of a hollow
sphere.

("Hollow, how are you?")

While there are criticisms of the CFC/ozone theory which cannot be
dismissed without first subjecting them to protracted and meticulous
scrutiny, proponents of these theories are yet to come up with
convincing explanations in the face of the hard evidence available and
the current theories which seem to be the best we have, and which are
generally subscribed to by the overwhelming majority of researchers in
the field of atmospheric science.

Social policy should be based on the best information available.

In the case of ozone depletion over Antarctica, the Montreal Protocol
was convened on the basis of the majority opinion of researchers in
the field, and was a response to what researchers regarded as a
potentially critical situation.

The current majority opinion amongst researchers, and those closely
associated with the field, is that CFCs are the primary cause of the
ozone hole over Antarctica in Spring.

Whether history proves them all to be wrong, and regards the Montreal
Protocol as being the natural response to an apparently critical
situation, based on the best information apparently available, only
history will tell.

I suspect that history will show that we got out of that one, and that
if we had let the situation continue for another 20 years, we would
have had serious environmental repercussions.

I suspect that if we had let it go on for 100 years, there wouldn't be
much history to tell anything. 

You did ask what we think, you certainly got what I think! :-)

Cheers

Ian Lowery

As the one wing'ed bird, said to the two wing'ed bird: "It's all a
matter of a pinnion".