OTTAWA - Canadian scientists who confirmed the link between ozone depletion and cell-damaging ultraviolet rays have warned that the danger goes well beyond human beings to crops, forests and animals.

They said their work enabled the first hard estimate of increases that would occur over the next few decades in ultraviolet radiation.

They said science must now study the impact on biological organisms that could affect agriculture and economic output.

"These increases on UV levels are important for studies on the effects on our biosphere," Mr Jim Kerr, a scientist with the government agency, Environment Canada, and co-author of the ground-breaking study, told a news conference on Friday.

The study, conducted in Toronto, provides the first conclusive evidence that depletion of the atmosphere's ozone layer exposes populated areas of the Northern Hemisphere to greater ultra-violet radiations.

"We were able to link the increase in ultraviolet fairly accurately to the decreases in ozone, because they were so large," he said.

The ozone layer shields the Earth from over 90 per cent of ultraviolet light, which is invisible and can cause skin cancer and eye damage, At certain wave-lengths, called UV-B it can be harmful to virtually all biological processes.

Mr Ralph Daley, a biologist at Environment Canada's National Water Research Institute, said that exposure to excessive UV can cause genetic damage to plants, disrupt reproductive processes, alter food chains and cause the displacement of entire species.

"This study takes us from the hypothetical realm to the realm of reality," he said.

"If one does a conservative extrapolation, by the year 2005, when the ozone hole is expected to be at its maximum, we could have as much as a 50 per cent increase in the level of UV-B."

Mr Daley said such increased levels of radiation had been shown to alter biological organisms experimentally exposed to UV-B.

He said UV light could alter the DNA structure of organisms and elaborate photo-chemical repair processes.

"We humans are able to adapt and protect ourselves with sunscreens … the more serious consequences are ecological," he said.

"The scientific challenge now is to determine which organisms are affected most dramatically and which not." - REUTER.