From GAVIN GREENOAK
‘Sunscreens and the protection racket’ (22 January) in Australia is
such a shameful bundle of confusions, almost any comment only adds to it.
However, almost every working day, we determine the protection of sunscreens
from the UVB and A induced sunburn response on human subjects. (We are not
‘supported’ by industry as Brett Wright stated, or by the University – we
run a business, and customers pay for an independent service.)
It is agreed that UV can be a skin carcinogen. A sunscreeen filter (not
a ‘block’) works by reducing the amount of biologically effective UV reaching
the skin. When two sunscreens of unknown SPF (sun protection factor) are
tested together using a light source which closely approximates sunlight
UV emission, and one protects the skin for twice as long (or for the same
time with double the dose) as the other, then the first one gets an SPF
rating of double the second one, on that test subject.
We do this experiment nearly every day, and 2+2 always = 4 rather than
something else, and the UV-transmission of an SPF 30 is always half that
of an SPF 15. Sunscreens on the shelves in Australia range from SPF 4 to
100+, but over 15, the consumer is prevented by law from knowing which are
more protective than others.
Advertisement
Notwithstanding the confounding logic of Marks, and the pessimism of
Reeve, an SPF as determined by an internationally recognised scientific
method and Australian Standard, shows by compelling logic and direct evidence,
for all to see, that sunscreens reduce the effectiveness of biologically
effective UV.
This being the case, it is hardly surprising that there is considerable
published data showing that sunscreens do indeed reduce the risk of skin
cancer in mice and humans, and that there is no published evidence to
the contrary.
Gavin Greenoak The Australian Photobiology Testing Facility Sydney,
Australia
