Ultraviolet radiation, particularly the shorter wavelength UV-B (280-315 nm) and UV-C (below 280nm nm), is known to detrimentally affect biological and chemical processes of living organisms (1), (2). Exposure to elevated levels of ultraviolet radiation can cause adverse effects on growth, photosynthesis, protein and pigment control, reproduction and can cause damage to DNA3. In humans, exposure to ultraviolet radiation can manifest itself in the development of skin cancer, cataracts and weakening of the immune system.

Ecology

Marine foodwebs, based primarily on phytoplankton, are sensitive to alterations in its biomass, and so impacts on phytoplankton will have corresponding repercussions in ecosystems. More than 50 per cent of the Earth's primary productivity derives from aquatic ecosystems (4), so UV-B induced inhibition of the organisms responsible for this productivity - phytoplankton - has potentially devastating consequences. Scientists have constructed models to predict how ecosystems will respond to elevated UV-B radiation. One such model predicts that following a 17 per cent decrease in primary production due to elevated UV-B radiation, a 27 per cent decrease in fish and invertebrates would result. Losses could be even greater as damage to early stages of juvenile fish, which are more sensitive to UV-B exposure, are not considered in this model (5), (6).

As a consequence of ozone layer thinning, spawning fish and other marine fauna suffer damage similar to sunburn as well as impaired development and other abnormalities. In springtime, when ozone depletion is greatest and UV-B levels are at their maximum, many fish species are also spawning. At this stage respiration is through their skin as their gills are not developed. The UV-B rays blister the skin of these young fish causing it to thicken. This slows down the uptake of oxygen, stunting growth and leaving them vulnerable to predators (7). UV-B induced dermal sun damage and melanomas are reported in a variety of fish species (8), (9), (10). Recent research has also revealed that UV-B radiation can interact with hydrocarbon pollutants in the sea, making them up to 10 000 times more toxic (11).

Human Health

Exposure to ultraviolet radiation also directly impacts human health. These negative health effects include photoaging of the skin, skin cancer, cataracts, and incidence of ocular melonoma and squamous cell carcinoma of the eye. Although it is clear that exposure to UV-B radiation in humans is dependent on a variety of conditions - primarily climatic and behavioural effects - the US Environment Protection Agency developed a model incorporating the ozone depletion scenarios developed by the Scientific Assessment Panel of the Montreal Protocol (12). This predicted that, even with full compliance with the various amendments and adjustments to the Montreal Protocol, more than 25 million additional cases of cataracts are expected worldwide by 2050. This model was based on US data and it is possible that under-nourished populations may be at greater risk13.

A similar model provides estimates of the additional cancer risks in populations annually, based on estimated changes in UV-B over time14,15. Assuming full worldwide compliance with the Montreal Protocol and amendments it is predicted that by 2060 there will be approximately 90 million additional cases of skin cancer13.