Scientists have genetically modified tobacco plants to knock out a gene that helps turns nicotine into one of the carcinogens in cured tobacco.

The Philip Morris-funded North Carolina State researchers say the work could lead to less cancer-causing chewing tobacco. In large-scale field trials, they compared the levels of N-nitrosonornicotine, a chemical known as NNN, between GM tobacco plants and a control group. They found a six-fold decrease in NNN and a 50 percent overall drop in a whole class of nasty substances known as tobacco-specific nitrosamines.

The new work appears in Plant Biotechnology Journal. The researchers do not state how much the use of the tobacco could reduce the health risks from chewing tobacco. Given the other 15-odd carcinogenic substances present even in chew, they do note that the best way to avoid cancer from nicotine is not to use it.

Not oblivious to consumer opposition to many genetically modified crops, the researchers then created a line of tobacco plants missing the same gene they'd previously knocked out through conventional breeding techniques. They are currently trying to introduce that mutation into commercial tobacco lines, presumably avoiding a genetically modified organism label.

According to U.S. Department of Agriculture records, Philip Morris, a tobacco giant which had $66 billion in revenue last year, has run dozens of field trials for genetically modified tobacco varieties. All those studies beg the question: Can Big Tobacco genetically engineer the cancer out of the cancer stick? And if so, at what cost? (One can almost imagine an advertising slogan: New GM Chewing Tobacco – Now Lower in Cancer!)

We'll be trying to find an answer for you over the next week with a rolling investigation. UPDATE (3/20): The first post on my research is now up. The USDA says that Philip Morris has conducted 33 field trials of genetically engineered tobacco, more than twice as many as any other tobacco company.

Grist: Gene 'knockout' floors tobacco carcinogen.

Image: flickr/amareschal. *Tobacco drying.