Friday, 28 May 2010

Yes, the dose makes the poison


Looking at my web stats, I see that this site has been visited no fewer than 29 times in the last few days under the search term "chris snowdon dose makes the poison". Why someone should so persistently associate this phrase with me, I can't say, but for that Googler, I hope the following helps:-

The dose makes the poison is a fundamental principle of toxicology. It is generally attributed to the 16th century scientist Paralcelsus, who said:

"All things are poison and nothing is without poison, only the dose permits something not to be poisonous."

In other words, everything is toxic and everything is harmless. It is the quantity that makes the difference. It is this basic piece of scientific understanding that makes the last Surgeon General's claim that "there is no safe level of secondhand smoke" so risible. It is also one reason why scientists scoff at the homeopathic claim that remedies become more potent as they become more diluted. And it's one reason why the term 'toxic chemicals' can be misleading. When we talk about toxic waste, everyone knows what we mean. Saying that a product contains 'toxic chemicals' implies that these chemicals are dangerous at the levels found in the product. Sometimes, however, the reality is that they could be toxic at higher quantities or under experimental conditions. That's true, but it would be true of oxygen and vitamin C too.

Ignoring the principle that the dose makes the poison makes it possible to claim that acrylamide in french fries, or "gender-bending" phthalates in shower curtains, or nitrosamines in smoker's carpets can cause cancer. It's junk. All these things can be harmful, but not at the levels found in real-world situations. (If you really need to know why these claims are junk, click here, here and here).

I hope that helps whoever was searching. I only wish I could assist the people who found the site by Googling "weasel in wales", "politicians that like fruit cakes" and "fisting with pipes". Alas, you will need to go elsewhere for that kind of information. 



8 comments:

Fredrik Eich said...

I've always assumed that homeopathy came about because essence of something that's hard to get hold of goes around a lot more if it has been diluted. Clearly if cocaine dealers cut their goods too much they will, rightly, end up with no customers. Dealers in homeopathic remedies have no such worries because I should imagine that something diluted to water, tastes a bit like water and probably has the same healing properties as water. In fact, because I am a bit stuck in my ways, I would even go as far as to say that it is in reality just water. Maybe I'm a bit simple.

Michael J. McFadden said...

Chris, I believe there is actually a small amount of weakness in the toxicological defense per Paracelsus. In his time he was speaking of the effects of poisoning as carcinogenic effects were pretty much unknown as a class.

Today scientists are divided between the threshold and non-threshold theory camps for carcinogenesis, with the non-thresholders claiming that even a single exposure to the smallest possible immeasurable unit of a substance or condition can cause cancer.

There are two problems with this however:

1) Many scientists disagree with the theory, claiming that something akin to chaos theory or prinicples of uncertainty enter the equation significantly when the exposures become too small. These scientists claim that a butterfly flapping its wings in Kansas can NOT ever "cause" a typhoon in Vietnam.

2) Even if we accept the no-threshold theory the Antismokers' characterization of secondary smoke is misleading. To use the word toxic or dangerous to describe the level of exposure to secondary smoke that would normally be encountered today in any decently ventilated establishment would be like using those words to describe reaching out the door to grab the morning paper without UV safety gloves on or dining in a restaurant where someone was drinking a beverage containing the highly volatile Class A Human Carcinogen ethyl alcohol.

Use of "no safe level" to describe those exposures would be highly misleading and destructive.... just as its use to describe secondhand smoke is.

Michael J. McFadden

Anonymous said...

"I see that this site has been visited no fewer than 29 times in the last few days under the search term "chris snowdon dose makes the poison".


I have to confess that I find this ability to know how a site is reached a bit disconcerting.

It's a bit like showing up at someone's house late, and the host telling you that he knows that you were delayed because you took a detour on the way and bought a bottle of whiskey, shotgun shells and a bag of pot.

Fredrik Eich said...

"I have to confess that I find this ability to know how a site is reached a bit disconcerting. "

It's one of the ways, if not the main way search engines make money!
I wish I had thought of it!

Fredrik Eich said...

"fisting with pipes"
Chris,
Maybe "Velvet Glove, Iron Fisting"
would have been a more amusing title for your blog!

Snowdon said...

"I have to confess that I find this ability to know how a site is reached a bit disconcerting. "

Not as disconcerting as seeing what people search for on the internet, I assure you.

Anonymous said...

"Not as disconcerting as seeing what people search for on the internet, I assure you."

I usually visit your site by clicking the link to your book from another blog I follow. Ever since reading your response, I've been contemplating the practical joke of instead typing something like "dirty-barnyard-fantasy-where-can-I-get-free-crack-cocaine-Chris Snowdon-smoking-blog" into Google every time I visit.

Then I realized that only I would probably find it funny, and no one would get the joke unless I explained it first, which kind of kills the spirit of the whole thing.

Oh, Well. Another dream deferred.

Michael J. McFadden said...

One of our longtime warriors in the U.S., Dave Hitt, wrote an amusing piece on how search engines were finding his site. One of the odder search terms was "Thora Burch's nipples."

See: http://www.davehitt.com/jan01/searchme.html?ref=3b.org

and check out his "The Facts" on "passive smoking" while you're there!

:>
Michael