The Dose Makes the Poison

There’s a principal in toxicology that says any substance can harm or kill you if you’re exposed to enough. In other words, the dose makes the poison [1]. This theory is credited to the 15th-century physician, alchemist, and astrologer Paracelsus [2], [3]. We’re all familiar with substances that are dangerous or even lethal at very low concentrations like botulism toxin and lead (especially for pregnant women, babies, and growing children). But, did you know there is also a mean lethal dose (LD50) for seemingly harmless things like water (>90,000 mg/kg) and sugar (29,700 mg/kg) [4]?

Figure : Painting of the Swiss physician Paracelsus, born Theophrastus von Hohenheim in 1493. From Wikimedia Commons [3].

Do you think ‘less is better’ when it comes to smoking cigarettes? I mean, at least if you cut down on how many you smoke per day, you’re much better off, right? You, like many other people, probably think that if you smoke just one cigarette a day, you’ll escape the ravages of coronary heart disease (CHD) and stroke. Maybe your quitting plan is to cut down on the number you smoke every day. Check in with yourself and be honest. Is this how you think? If you still hold on to thoughts like these, as your friend I have to tell you the hard truth - you’re dead wrong.

What the Data Show

Since the dawn of smoking, the impression has always been the more you smoke the worse it is for your health. But more importantly, the general public has the idea that smoking just a few cigarettes a day is relatively safe. This mindset has been smacked upside the head by a recent first-of-its-kind study. Let’s break it down and look at what the researchers found.

Earlier this year, researchers in the United Kingdom and China analyzed the data from 141 cigarette smoking studies done from 1946 to 2015 and extracted information on the impact of light smoking (1-5 cigarettes a day) on the risk of CHD and stroke in adult men and women [5]. Overall, the data showed that smoking about one cigarette day gave people (men and women) 40-50% of the risk of CHD and stroke that comes from smoking 20 cigarettes a day. That’s freaking scary.

The gender-related data reveal the increased risks for men and women who smoke about one cigarette a day compared to people who never smoked. The researchers also separated the data based on whether confounding factors were considered. Confounding factors are things that can make people’s risk of CHD and stroke even greater like high blood pressure, high body mass index (BMI), sedentary lifestyle, and diabetes. Table 1 below summarizes the major study findings.

Table 1: Increased risk of coronary heart disease (CHD) and stroke in men and women who smoke about one cigarette a day compared to people who never smoked [4]. Percentages in red have been adjusted based on people with three or more confounding factors.

The data are striking, particularly when it comes to the increased risk of CHD for women who smoke about one cigarette a day. In addition, it’s alarming to see that women with confounding factors have double the risk of CHD and stroke - from about one cigarette a day.

Ignore the Funhouse Mirrors

This quote is taken directly from the study just discussed. Let it sink in. Share it with those you know and love who smoke.

"No safe level of smoking exists for cardiovascular disease. Smokers should aim to quit instead of cutting down to significantly reduce their risk of these two common major disorders [coronary artery disease and stroke] [4]."

Now that we know even one cigarette a day has a greater risk of causing CHD and stroke than anyone realized, what about ways to reduce the deadly chemicals that enter the body, even from just one cigarette? Some critical thinking is definitely in order when it comes to debunking the misconceptions that are out there.

First, understand that tobacco companies put additives in cigarettes that enhance the speed and efficiency of nicotine delivery to your brain and to reduce some unpleasant effects of smoke from burning tobacco entering your lungs (Figure 2) [6]. They stay one step ahead of people who try to ‘cut down’ as a strategy for quitting completely.

Figure : Illustration showing cigarette additives designed to increase nicotine addiction and make cigarettes smoking more pleasant [6].

The tobacco industry is always devising ways to deflect blame, distort, and/or stop the flow of information from scientific studies which confirm the harmful and deadly effects of cigarettes. Over the years, part of their strategy involved advertising that developed, reinforced, and perpetuated the idea that smoking filtered cigarettes, and/or smoking ‘light,’ ‘ultra-light’ or ‘mild’ brands are better for smokers’ health than taking toxic lungfuls from those unfiltered Camels.

In 2009, the US Food and Drug Administration (FDA) banned the use of these misleading terms on cigarette packaging under the Family Smoking Prevention and Tobacco Control Act (FSPTCA), calling such claims “health fraud” and setting rigorous standards for the industry to meet for modifying the risks of any tobacco products [7], [8]. As you would expect, cigarette manufacturers countered by replacing the banned terms with corresponding colors (e.g. ‘gold’ replacing ‘light’ and ‘silver’ replacing ‘ultra-light’) [9].

Sure enough, despite the FSPTCA, a 2018 study showed that 92% of smokers could still easily identify their preferred brand and 68% could name the color associated with the package [10]. Therefore, cigarette manufacturers successfully circumvented the new FDA rules by using different marketing tactics. Research efforts in a related area have also shown that smokers often misinterpret advertisements for reduced nicotine cigarettes believing they are less harmful than regular cigarettes, and the advertising makes smokers think more positively about low nicotine brands [11], [12].

As you’re designing your plan and modifying your behavior to quit smoking, it’s clear that quitting altogether is the best way to minimize the risks to your health. Don’t fall into the propaganda trap and think you can cut down over time or use ‘light’ or ‘silver’ brands to wean you off and reduce the damage to your body. Let science be your strength and your guide.


[1] “The dose makes the poison,” Wikipedia. 02-Jul-2018.

[2] “Paracelsus,” Wikipedia. 01-Jul-2018.

[3] Q. Matsys, Paracelsus. Louvre Museum of Paintings, Paris, France.

[4] “Median lethal dose,” Wikipedia. 22-Jun-2018.

[5] A. Hackshaw, J. K. Morris, S. Boniface, J.-L. Tang, and D. Milenković, “Low cigarette consumption and risk of coronary heart disease and stroke: meta-analysis of 141 cohort studies in 55 study reports,” BMJ, p. j5855, Jan. 2018.

[6] “New Report Details How Tobacco Companies Have Made Cigarettes More Addictive, More Attractive to Kids and More Deadly,” Campaign for Tobacco-Free Kids, 06-Jun-2017. [Online]. Available: [Accessed: 01-Aug-2018].

[7] “Labeling - Light, Low, Mild or Similar Descriptors,” US Food & Drug Administration, 19-Jan-2018. [Online]. Available: [Accessed: 01-Aug-2018].

[8] “Compliance, Enforcement & Training - Family Smoking Prevention and Tobacco Control Act - An Overview.” [Online]. Available: [Accessed: 01-Aug-2018].

[9] G. N. Connolly and H. R. Alpert, “Has the tobacco industry evaded the FDA’s ban on ‘Light’ cigarette descriptors?,” Tobacco Control, p. tobaccocontrol-2012-050746, Mar. 2013.

[10] H. R. Alpert, D. Carpenter, and G. N. Connolly, “Tobacco industry response to a ban on lights descriptors on cigarette packaging and population outcomes,” Tobacco Control, vol. 27, no. 4, pp. 390–398, Jul. 2018.

[11] M. Mercincavage, M. L. Saddleson, E. Gup, A. Halstead, D. Mays, and A. A. Strasser, “Reduced nicotine content cigarette advertising: How false beliefs and subjective ratings affect smoking behavior,” Drug and Alcohol Dependence, vol. 173, pp. 99–106, Apr. 2017.

[12] R. L. Denlinger-Apte, D. L. Joel, A. A. Strasser, and E. C. Donny, “Low nicotine content descriptors reduce perceived health risks and positive cigarette ratings in participants using very low nicotine content cigarettes,” Nicotine & Tobacco Research, p. ntw320, Dec. 2016.