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

UV and Australian Plants

Larkum’s work began about 4 years ago. “The initial motivation for this work was concern about the effects of ozone depletion,” he says. “Now we have seen that plant growth inhibition from ultraviolet radiation is a problem that is there anyway and is largely a problem that has been ignored in the past. So there are lots of other interesting aspects to follow concerning how plants grow under the Australian conditions of high natural levels of UVB.”

It is surprising that even with existing, normal levels of UVB there is quite severe inhibition of plant growth under high sunlight conditions. For example, there are kelps that are normally found in marine waters around Sydney. These are the large brown algae that you can just see below the tide level and in rock pools that often form large forests around the shores of Australia. These kelps tend to look really scraggy and bleached in the middle of summer. This is because they are susceptible to the UVB and the ends of these plants get quite bleached off. But if they are screened from UV, when they are in this condition, they grow very well.

Many other algae and land plants are also susceptible to UV light and they probably spend a lot of energy producing screening compounds and repairing the damage. The indications are that if the UVB were to be removed the plants would be more productive, growing more quickly and producing more fruits or seeds. On the other hand if the UVB were to be increased there would be a drop of productivity. The effects of the levels of UVB on plant life haven’t been properly studied in Australia yet even though there are already very high levels of UV occurring naturally here. Larkum thinks increases of 2-5% in UV light might be too small to register any difference using current techniques but feels certain that a change of 10% would definitely be noticeable.