CONTENTS

Introduction
Human Skin Cancer
Sunscreen and Fabric
The Mouse Model of Cancer
Studies Using Skin Tissue
Drugs and Sunlight
Plant and Algae Growth
Conclusion
Glossary
Bibliography

Research Implications

Moore sees both long and short term implications for his research. For the short term he sees the need for appropriate warning to be given to the people using the drugs. In the longer term he hopes to be able to point out features of the molecules which are causing the adverse effects and thereby help to design new drugs which have the same therapeutic result but which are less capable of the detrimental reactions.

As things stand, the reports of adverse drug reactions are accumulated by Canberra in the Department of Health. The level at which the information gets transferred to individuals is variable but in most of the pharmacopieas, that is the reference books which describe the properties of the drugs and their formulations, where necessary it will mention that they are liable to cause, or have caused, photosensitivity (light sensitivity) problems. “In these cases it should go on to say that patients should be warned.” says Moore. “Even when they are warned it is usually in fairly terse terms. Simply that a certain compound may cause photosensitivity effects. If someone were to receive that warning they should make sure that they wear a broad spectrum sunscreen. If they have to go out into the sun, and it is pretty hard to avoid it, then they should make sure they are properly protected. Hazy days are a problem because a person might think that the sun is not shining, due to a hazy cloud cover, when in actual fact strong UV is still getting through.”

About 15-20% of drugs are capable, to a greater or lesser extent, of producing this effect but only a certain percentage of people are vulnerable. Those with light skin are less well protected because they have less natural protection. It also depends on the state of a person’s immune response system. The role of vitamins in protection is not completely certain. At this stage the use of vitamins as protection is really just a hypothesis but Moore says that it has been shown with experimental animals that if their dietary intake is supplemented by vitamins, particularly vitamin A, they have more protection from skin cancers as well as a number of other cancers.

There are two major families of drugs which are photosensitive and are in regular use by a lot of people. Firstly there are the so-called anti-inflammatory drugs. (The photosensitive effects of these drugs tend to make this description a contradiction in terms since they can cause skin inflammations.) A number of compounds used as anti-inflammatory drugs, in the treatment of arthritis for instance, are able to interact with light. Moore has done quite a lot of work with this group of drugs during the last few years and a number of them have now been identified as being very reactive photochemically. One of them, called benoxaprofen, was actually withdrawn from the market because it caused very serious photosensitivity aw well as liver problems. It never actually got onto the market in Australia but was used for a year or two in England and Europe before it was withdrawn. There are some other substances, that are still available, which have a similar chemical structure to benoxaprofen but which are not as extensive in their photosensitive effects.

The other major light reactive group is the diuretic drugs. Diuretics are the drugs which aid the bladder by effectively draining out excessive liquid held in the body. Both these classes of drugs, anti-inflammatory and diuretics, are used more and more by elderly people. Fortunately elderly people are perhaps more sensible in their exposure to the sun. “They’ve been there, done that and are generally more cautious than younger people about damaging their skin by sunbaking. The worrying thing about older people however is that in their retirement they often move north to Queensland, to places like the Gold Coast and the Sunshine coast, and are therefore perhaps exposing themselves to more risk. But generally speaking as the skin gets older it becomes more wrinkled and there is a thicker layer of dead skin and so it has in fact extra protection,” says Moore. “Nevertheless the aging and loss of elasiticity of te skin is accelerated by sunlight exposure.”