And then there’s nicotine. This highly addictive drug isn’t a carcinogen, but it’s not entirely benign either. It increases heart rate, constricts blood vessels, and contributes to high levels of cholesterol. There’s some evidence that it could stop cancerous cells from self-destructing or promote the growth of blood vessels that bring oxygen and nutrients to tumours. But both of these claims come from studies in lab-grown cells. “It’s not clear if any of this works in a live animal,” says Hecht. “The big thing [about nicotine] is the addiction.” Nicotine is a potent drug – it’s the one chemical that keeps smokers inhaling all the rest.
Nicotine’s addictive properties have led to some spectacular backfires in attempts to create safer cigarettes. From the 60s and 70s, the tobacco industry marketed “low-tar” cigarettes as safer versions of their normal cousins. These so-called “mild”, “smooth” and “light” alternatives contained tiny vents in their filters, which were meant to allow fresh air to dilute the tar – the collective term for the chemical gunge in smoke.
These cigarettes were tested with machines that, sure enough, measured a lower concentration of tar in the ensuing smoke. But, surprise, people aren’t machines. As the smoke from these brands also contained less nicotine, smokers would get their fix by taking longer drags, smoking more frequently, or simply blocking the filters with their fingers. They ended up inhaling more smoke, and despite the industry’s claims, exposed themselves to the same level of carcinogens.
Smokeless tobacco products fare little better. Even though they are sucked, chewed and sniffed, and never set on fire, they still contain many of the same carcinogens as cigarettes, and have been linked to mouth, oesophageal and pancreatic cancers. The one possible exception is snus, a Swedish product that’s not unlike a “tobacco-stuffed teabag” that you stick under your lips. It’s manufactured according to rigorous standards that limit the amount of nitrosamines in the final product, while still retaining that craving-satisfying nicotine. Snus is billed as the reason for Sweden’s low rates of lung and oral cancers, compared to countries where cigarettes are the dominant tobacco product.
“It’s much safer [than smoked products] but not entirely safe, and there’s a possibility that it still poses a cancer risk,” says Benowitz. Indeed, some recent studies have suggested that snus users have a higher risk of pancreatic cancer, and a higher risk of dying from cancer. “If you simplistically said everyone stopped smoking and used snus, there’d be a tremendous health benefit, but the question is whether they would do that,” says Benowitz. His concerns are that snus could make it harder for active smokers to give up their habit by fuelling nicotine addiction, or act as a gateway drug that entices non-smokers to start. “It’s probably better than smoking, but you probably don’t want to put it in your mouth,” says Hecht.
The same arguments apply to e-cigarettes – battery-powered devices that look like cigarettes, and release a nicotine vapour without any of the accompanying carcinogens. At least, that’s the theory – there’s scant data on what they actually release, and how that varies from brand to brand. An analysis from the US Food and Drug Administration showed that some still contained detectable traces of nitrosamines. “In theory, they could be safer than snus,” says Benowitz. “But there’s been hesitation around them because they are unregulated, so who knows what you’re getting.”
The use of both snus and e-cigarettes will probably remain highly controversial, even after more data comes in. This reflects a tension in public health circles: given smoking is so addictive and damaging, is it acceptable or even ethical to reduce that harm by advocating products that are safer, but still not safe? “If we’d never heard of cigarettes, we’d look at a smokeless tobacco product and say, ‘This thing should be banned’,” says Hecht. In a world where tobacco never existed, these arguments would be moot. But that world does not exist; what do we do in this one?