Bryan Caplan  

Alcohol and Non-Linear Dosage Effects

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Our years overlapped, but when I was an undergrad at Berkeley, I never met Aaron Wildavsky. My loss. Here's a great passage he wrote (along with Adam Wildavsky) for Henderson's encyclopedia:

Another questionable assumption is that cancer causation is a linear process, meaning that there is no safe dose and that damage occurs at a constant rate as exposure increases. This is known as the "linear no-threshold hypothesis." Scientific evidence increasingly shows that there are indeed threshold effects.
His example:
Consuming two gallons of 100-proof liquor is an hour would be enough to kill most of us. If the linear no-threshold hypothesis applied to alcohol, one would expect that if 256 people consumed an ounce of liquor each, then on average one of them would keel over and die. It would only be a slight exaggeration to say that were the EPA to regulate ethyl alcohol... the same way that it regulates other chemical compounds, we would each be limited to sixteen-millionths of an ounce per lifetime.
Hmm. I wonder whether Aaron would have advised me to take to drink?


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COMMENTS (5 to date)
David N. Welton writes:

Of course, you can choose how much alcohol to consume. Plenty of things that are regulated are regulated because they are, indeed, present in small undetectable quantities and you consume them whether you like it or not if you're not made aware of it. This could perhaps be described as 'information asymmetry', another thing that you economists might talk about more to connect with the public's anti-market bias.

Lee writes:

I just came across this idea in a book the Overcoming Bias bloggers are always pushing, Probability Theory by E.T. Jaynes. In the preface he writes:

A common error, when judging the effects of radioactivity or the toxicity of some sub-stance, is to assume a linear response model without threshold (i.e. without a dose rate belowwhich there is no ill effect). Presumably there is no threshold effect for cumulative poisonslike heavy metal ions (mercury, lead), which are eliminated only very slowly, if at all. Butfor virtually every organic substance (such as saccharin or cyclamates), the existence of afinite metabolic rate means that there must exist a finite threshold dose rate, below whichthe substance is decomposed, eliminated, or chemically altered so rapidly that it causes noill effects...

His writing has a lot of vigor. You can read the whole thing online here in html.

Mr. Science writes:

I am a cancer researcher, and I can assure you that continuous exposure to small doses of a carcinogen will lead to cancer. Carcinogens are mutagens, ie, substances that change your DNA, often fairly randomly. Most of the damage is repaired, and if some gets past the repair systems then it is often a non-dangerous change. However, if you mutate randomly over time you will eventually take out enough proto-oncogenes or tumor suppressors to cause a cell to become cancerous. This takes a long time, and it is a cumulative process, which is why cancer rates increase with age. As such, substances that cause a minor increase in the mutation rate have an effect directly related to the period of exposure. Comparisons to alcohol or other acute poisons is either ignorant or disingenuous.

Dr. T writes:

The only people who espoused the linear response toxicology theories were dishonest toxicologists and pseudo-environmental (we hate progress) groups. We physicians know from pharmacological studies that all compounds have thresholds for effects (good effects, side effects, and fatal effects all have different mean thresholds with moderate to huge variations between persons). There are a few stupid physicians who believe that even minute amounts of a carcinogen can cause cancer, but their believe is not based on medical or scientific evidence. These are the same stupid physicians who believe that magnetic fields around power lines cause leukemias and that cell phones cause brain cancer. Like most professions, we have our share of bad apples.

TGGP writes:

I hear nutmeg and cough-syrup have very non-linear effects.

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