The federal government has plans to take a new look at the use of marijuana for people who are suffering from painful diseases such as cancer, AIDS and multiple sclerosis.

All use of marijuana is now illegal in Canada. But if a scientific study of the drug shows that it can help relieve pain in some people, it could be legalized for medical use only.

Marijuana is the common name of Cannabis sativa, a plant which contains more than 400 chemicals. What is commonly referred to as marijuana ("grass", "pot", "weed") in North America is usually made up of crushed cannabis leaves, flowers, and often twigs.

Health Minister Allan Rock announced yesterday that his department is putting together guidelines for a scientific look at marijuana. The study would examine how the drug should be administered, and how a safe supply could be distributed to patients.

"There are people who are dying," Mr. Rock said. "They want access to something they believe will help with their symptoms. We want to help."

The Health Department has already consulted with the Food and Drug Administration in the United States - which is also planning similar trials - about acquiring marijuana for the tests.

Making marijuana available to patients by prescription will not mean changes to the criminal code. Marijuana could be administered under an existing section of the Food and Drug Act, which allows for special access to prohibited substances.

The belief that marijuana eases pain in some patients has been growing -- although people continue to face criminal charges across Canada even when they claim to be using it for medical purposes.

THC (delta-9 tetrahydrocannabinol) is the main psychoactive part of marijuana. When marijuana is smoked, THC is absorbed from the lungs to the bloodstream within minutes.

Mark Crossley is a 38-year-old Nova Scotia man with an inoperable brain tumor. He was sentenced last week to four months of house arrest and 18 months probation for growing marijuana in his backyard. He said he received the sentence even after the court was told he smoked the drug to deal with the painful headaches and appetite loss caused by his cancer. His doctor approved.

Mr. Rock said his announcement is not a step toward a widespread legalization of the drug.

"This has nothing to do with legalizing marijuana," he said. But he added, "I think Canadians support on a compassionate basis, if someone is dying, access to a substance that could alleviate their suffering."

An Edmonton doctor who specializes in pain management agrees with the federal government's move. Doctor Helen Hays studied a patient who smoked marijuana to fight the symptoms of a painful muscle disorder . "There was a tremendous improvement," she said. She also says that smoking marijuana brings its own side effects and doesn't work for everyone. "We all need to know an awful lot more about it."

Doctors can currently prescribe a synthetic form of marijuana, but it is expensive, and many patients complain that oral forms of the drug don't work as well as smoking it.

Several American states have already approved the medical use of marijuana. It was taken to a vote in seven U.S. states and the District of Columbia.

A similar bill was also recently presented in the British House of Commons in London.

1. When marijuana is smoked, who is absorbed from the lungs to the bloodstream within minutes?