Australians might think twice before puffing on a cannabis joint to ease their physical pain, with a new study finding it is more cancerous than smoking cigarettes.

The research, conducted by University of Western Australia Professors Gary Hulse and Stuart Reece, published in the medical journal Archives of Public Health shows cannabis is causal in 27 cancers, against 14 cancers for tobacco.

Citing the new research Drug Free Australia (DFA), a peak body advocating for regulated drug use, warned that "it is unsafe to rely on CBD (Cannabidiol) as the 'miracle cure' that some, who advocate legalisation of the drug, are claiming it to be".

The paper relies on data gathered from the Centres for Disease Control and Prevention in the US from 2003 to 2017.

It showed that US states where cannabis use has been legalised or decriminalised are significantly over-represented in various cancers, many of which are fatal.

Cannabis and its many variants including THC, which is common in vapes, can cause cancers including breast and lung, colorectal, Hodgkins and Non-Hodgkins Lymphoma, liver, thyroid, and pancreas, as well as heightening risk factors for melanoma and acute myeloid leukemia.

DFA also referred to another recent study of birth defects throughout Europe finding that cannabis was also a major factor in 89 of 95 birth defects tracked there.

The pair of psychiatrists maintain that cannabis use is responsible for literally shattering chromosomes. In a process called "chromothripsis", the body's DNA repair mechanisms become imperfect leading to dangerous mutations.

"The message is clear: CBD and cannabis for medicinal purposes are dangerous and are not a safe cure for illness," DFA said.