The dose makes the poison

Posted on April 01, 2014

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by Cami Ryan

Paracelsus was a 16th century Swiss German physician, alchemist, astrologer who found the discipline of toxicology. He came up with this basic principle of toxicology: The dose makes the poison.

"All things are poisons, for there is nothing without poisonous qualities. It is only the dose which makes a thing poison."

So many of us misunderstand basic chemistry and what 'toxic' really means. I can relate. Chemistry was my WORST subject in high school. Most of what I have learned (and since become interested in) has been cultivated through my PhD studies and in projects since then.

Toxicity is an indicator of how poisonous a substance is to a biological entity. Any chemical can be toxic if absorbed or consumed in large enough amounts.Chemistry is all around us and we are all comprised of chemicals (matter). Some chemicals are man made others occur naturally: in our bodies, manufactured in plants, in our food and in the air we breathe.  In fact, there are more naturally occurring chemicals than man-made ones.  Chemical reactions and interactions in our bodies occur all the time.

Joni Kamiya-Rose posted this status update the other day on Facebook which, in turn, inspired my blog post for today.

joni-rose-toxic

 

To Joni's last point… YES, wouldn't that be great! I can't imagine anyone who wouldn't want safer options.

To (further) clear up misunderstandings and provide some context on toxicity, I crafted this table.  In toxicology, the median lethal dose, LD50 (see column 3) is the dose required to kill half the members of a tested population after a specified testing time. The test was developed by J.W. Trevan in 1927. In the table , I outline a variety of familiar (some less familiar) materials and their toxicity levels.  Please note: the LD50 levels outlined in the table below are based on oral ingestions by rats.  Toxicity rankings are based on the EPA's categorization (I through IV) (Title 40 of the Code of Federal Regulations).

 

toxicity-table4

 

 

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Cami Ryan
is a Professional Affiliate with the U of S College of Agriculture and Bioresources