Growing evidence of marijuana smoke danger

OTTAWA, Aug. 14 (UPI) -- Smoking marijuana, like smoking tobacco, has toxic effects on cells, researchers in Canada found.

Rebecca Maertens of Health Canada and colleagues said people often view marijuana as a "natural" product and less harmful than tobacco. Their findings challenge the conventional wisdom that smoking marijuana is less harmful to health than inhaling tobacco smoke.

The researchers compared marijuana smoke and tobacco smoke in terms of toxicity to cells and DNA. Scientists exposed cultured animal cells and bacteria to condensed smoke samples from both marijuana and tobacco.

There were distinct differences in the degree and type of toxicity elicited by marijuana and cigarette smoke, the researchers found.

The study, to be published in the journal Chemical Research in Toxicology Marijuana, found marijuana smoke caused significantly more damage to cells and DNA than tobacco smoke. However, tobacco smoke caused chromosome damage while marijuana did not.