How a Toxicologist Might Look at Benzos
(original post December 6, 2013)
This morning I was thinking about going into the city (where I was once employed) and meeting for a holiday lunch with “the old gang” – all of whom are now retired (except for one – a young lady I called Rooster). Of course, that brought to mind the work that I had done in what now seems like another lifetime. I was an environmental scientist and had many opportunities to get involved in many diverse technical projects. One of my favorite areas was assessing risk from human exposure to toxic contaminants in various environmental media. That required looking at toxicological data and studies upon which many environmental standards are based.
So, I wondered, how would benzos stack up against some of the chemicals that are considered “nasty” with respect to human toxicity? I did a few “back of the envelope” calculations to get some sort of “feel” for what a toxicologist might think about benzo toxicity.
The first basic step is to find an NOAEL (no observed adverse effect level) for benzos. An NOAEL for a substance is essentially the highest level (based on observation) at which exposure to that substance causes no adverse effect (that can be observed). If a value for the NOAEL does not exist, it is often estimated by taking an LOAEL (lowest observed adverse effect level) and dividing by 10 – pretty simple stuff.
Once an NOAEL value is known for a substance (either through observation or estimation), “uncertainty factors” and “modifying factors” are applied to come up with a “safe dose” for that substance. At least one uncertainty factor of 10 is typically applied to the NOAEL to protect sensitive populations. This is usually done by dividing the NOAEL by 10. The default modifying factor is 1. The “safe dose” (called a reference dose) would be the LOAEL divided by 100 (10 times 10).
I have been on the benzo withdrawal forums for quite some time and have noticed that many individuals who have taken a daily dose of 0.5 mg Klonopin or Xanax for some time have gone into tolerance withdrawal and on into withdrawal after they have discontinued. This can serve as the LOAEL for this purpose – 0.5 mg/day (for Klonopin or Xanax).
This converts to a “safe dose” of 0.005 mg/ day. In order to compare this dose (and thus toxicity) to the toxicity of some of the substances for which there are doses considered “safe” by EPA’s Integrated Risk Information System (a large database), both “safe doses” must be expressed in the same units. The standard units are mg/kg-day (where kg is body weight). The “standard” adult is assumed to be 70 kg. So, for purposes of this exercise, the “reference dose” for Klonopin or Xanax would be 0.005 mg/day divided by 70 kg or 7x10-5 mg/kg-day.
Reference doses (in mg/kg-day) for some notable toxic substances follow. (Lower reference doses indicate greater toxicity.)
Warfarin (rat poison) 3x10-4
Strychnine 3x10-4
Arsenic 3x10-4
Benzene 4x10-3
Cadmium 5x10-4 (in water)
Methoxychlor (pesticide) 5x10-3
Malathion (pesticide) 2x10-2
TCE (degreaser) 5x10-4
So, Klonopin and Xanax would be about 4 times more toxic than the most toxic substances on this list (arsenic, strychnine, warfarin) using fairly standard toxicological protocol.
It is interesting that the FDA allows medical doctors (under the guise of ”medicine” and the liability protection of ”standard of care”) to literally prescribe toxic substances at doses that FAR exceed the doses that federal EPA and state environmental agencies would consider safe from exposure to the same substances in environmental media.
Even back when I was still taking the Klonopin knowing that it was killing me, I could not understand how the work I did could be so protective of human health based on theoretical environmental exposures to toxic substances, yet doctors are allowed to legally prescribe toxic substances which are directly ingested (not in theory but in reality) and call it “medicine.”
Now that I can think even more clearly, I still can’t get my head or my heart around this reality.  And society, at large, does not see it.   
I am not bitter or resentful at all for the anguish I have endured at the hands of “modern medicine” – just disillusioned in a sense…but still hopeful.
There is always hope, and it can do amazing things.