It’s remarkable how much truly bad science is related to marijuana research. The latest is this: Evaluation of the DNA damaging potential of cannabis cigarette smoke by the determination of acetaldehyde derived N2-ethyl-2′-deoxyguanosine adducts by Singh R, Sandhu J, Kaur B, Juren T, Steward WP, SegerbÉck D, Farmer PB
Now, some science monkey is likely to come along at this point and say “How dare you call it bad science? Do you know more than these researchers? Have you studied their work?” No. But it’s bad science. And I can tell by reading the final sentence of their abstract:

In conclusion, these results provide evidence for the DNA damaging potential of cannabis smoke, implying that the consumption of cannabis cigarettes may be detrimental to human health with the possibility to initiate cancer development.

The mere fact that they are implying negative possibilities about cannabis consumption in a scientific abstract makes it science by press release, which is, by definition, bad science.
They know, based on such a statement alone, that sensationalist media all over the world will give them publicity for their work without even looking at it.
They also know that they have absolutely no evidence that supports such conjectures — all they have is an interesting little datum of scientific trivia that says nothing, but may lead to further research. That, however, doesn’t get them in the papers.
Listen, I could conduct a study where I injected marijuana mixed with air into the bloodstream of rats causing all of them to die (from the injected air, of course), and end my abstract with a statement that this study implicates the possibility that THC in the bloodstream causes death. And Fox News would have a headline.
Just like they have today: Marijuana Not Only Gets You High, It Damages Your DNA

Researchers at the University of Leicester in England have found “convincing evidence” that pot smoke damages DNA in ways that could potentially increase the risk of cancer.

Paul Armentano does a nice job of taking down the Fox article.

Just for the record, in 2006, Tashkin led the largest population case-control study (yes, Dr. Tashkin actually performed research on humans, not ‘calf thymus DNA‰) ever to assess the use of marijuana and lung cancer risk. The study, which included more than 2,200 subjects (1,212 cases and 1,040 controls), reported that marijuana smoking was not positively associated with cancers of the lung or upper aerodigestive tract — even among individuals who reported smoking more than 22,000 joints during their lifetime.
Let the folks at Fox put that in their pipe and smoke it. [emphasis added]

It happens every time.
To be honest, it’s depressingly unrealistic to expect more of the media. They love this crap. But those who work in scientific fields must start holding their colleagues to some kind of standard of professionalism. This is intellectual dishonesty at its worst.