As a pathologist, I have studied how human cells are altered by disease; with colleagues, I have explored in the laboratory how cancer cells behave and respond to various treatments. A single human disease can involve thousands of changes in the arrangement and interaction of the 10,000 different kinds of molecules present in each cell.
While I have profound respect for those conducting legitimate research to expand our understanding of human biology, diseases and their treatment, I am dismayed by the recent spate of laboratory studies in which researchers expose cells living in artificial environments to e-cigarette liquids. The liquids invariably produce measurable effects, which lead to claims that e-cigarettes cause myriad diseases. These claims are further exaggerated in press releases and sensationalized media coverage.
E-cigarette consumers – vapers – need to understand that what happens in these lab experiments does not necessarily mirror cellular action in humans. Human cells nurtured in labs’ artificial environments are exquisitely delicate; even under perfect conditions, it is exceedingly difficult to keep them alive – a minor change in the environment can skew an experiment and even kill the cells.
Humans are far more resistant to small doses of chemicals than are cells in a petri dish. Famed biologist Bruce Ames wrote in 2000, “Humans have many natural defenses that buffer against normal exposures to toxins…Examples of general defenses include the continuous shedding of cells exposed to toxins. The surface layers of the mouth, esophagus, stomach, intestine, colon, skin and lungs are discarded every few days; DNA repair enzymes, which repair DNA that was damaged from many different sources; and detoxification enzymes of the liver and other organs.” (abstract here).
Ames made prescient comments about excessive regulation based on laboratory experiments: “Regulatory efforts to reduce low-level human exposures to synthetic chemicals because they are rodent carcinogens are expensive; they aim to eliminate minuscule concentrations that now can be measured with improved techniques. These efforts are distractions from the major task of improving public health through increasing scientific understanding about how to prevent cancer (e.g., what aspects of diet are important), increasing public understanding of how lifestyle influences health, and improving our ability to help individuals alter their lifestyles. Why has the government focused on minor hypothetical risks at huge cost? A recent article in The Economist had a fairly harsh judgment:
“‘Predictions of ecological doom, including recent ones, have such a terrible track record that people should take them with pinches of salt instead of lapping them up with relish. For reasons of their own, pressure groups, journalists and fame-seekers will no doubt continue to peddle ecological catastrophes at an undiminishing speed… Environmentalists are quick to accuse their opponents in business of having vested interests. But their own incomes, their fame and their very existence can depend on supporting the most alarming versions of every environmental scare. ‘The whole aim of practical politics’ said H.L. Mencken, ‘is to keep the populace alarmed — and hence clamorous to be led to safety — by menacing it with a series of hobgoblins, all of them imaginary.’ Mencken’s forecast, at least, appears to have been correct.’
“Aaron Wildavsky discusses worst-case risk assessment in his book But Is It True: A Citizen’s Guide to Environmental Health and Safety Issues: ‘We should be guided by the probability and extent of harm, not by its mere possibility. The search for possibilities is endless and it trivializes the subject. There is bound to be great diversion of resources without reducing substantial sources of harm. Consternation is created but health is not enhanced…Weak causes are likely to have weak effects. Our search should be for strong causes with palpable effects, like cigarette smoking. They are easier to find and their effects are much more important to control…The past necessity of proving harm has been replaced by a reversal of causality: now the individuals and businesses must prove that they will do no harm. My objection to this…is profound: our liberties are curbed and our health is harmed.’” (emphasis mine)
If lab studies were the standard for evaluating consumer products, then medicines already on the market would be in big trouble: One study found that half of marketed pharmaceuticals demonstrate cancer-producing properties in lab studies (here). A Journal of Pharmacology report terms standard human cell lab tests (genotoxicity assays) “misleading,” “irrelevant” or “false.” (here)
E-cigarette liquids are being vilified through such tests. Vapers should not be fooled by the irresponsible transformation of weak cause-and-effect analyses into hypothetical illnesses. Largely harmless products can be portrayed quite readily as dangers – coffee, for example , has not been linked to any serious disease, but one could point to lab studies showing that coffee kills cells (here and here) and promotes cancers (here). These claims would have about as much scientific credibility as the current claims against e-cigarettes.