DCHAS-L Archives Jun 12 2010 - Re: toxicity question

Date: Sat, 12 Jun 2010 10:04:37 -0600
Reply-To: DCHAS-L Discussion List <DCHAS-L**At_Symbol_Here**LIST.UVM.EDU>
Sender: DCHAS-L Discussion List <DCHAS-L**At_Symbol_Here**LIST.UVM.EDU>
From: Alan Hall <ahalltoxic**At_Symbol_Here**MSN.COM>
Subject: Re: toxicity question
In-Reply-To: <d3aa6.25829bb9.3944ea1f**At_Symbol_Here**cs.com>

Romona,

Once again, you take a long harangue (commom to us old Mountain/Desert Me n and Mark Twain afficianados) and cut to the basis of the discussion. ; I actually have carried theatrical fog in this manner - since it wouldn 't stay lighted - I'd suggest zinc chloride inhalational toxicity - - can lead to severe chemical pneumonitis and even bronchiolitis obliterans , but NOT in this exposure scenario to my knowledge; yours may be diffe rent) and therefore was no risk to anybody except us poor folks trying to u se red phosphorus-based matches --we all seem to have survived) and finally decided to use charcoal briquettes with dowsed water as an alternat ive. Neither was particularly safe, and neither caused illness in the particular theater in which we were doing this amateur performance in Alaska.

Geez, Romona, are we with Rin-Tin-Tin and his side-kick Rusty an d Lt. Rip Masters going to come over the hills with the mythical "Wh ite Buffalo" going to be the ones?

The EU "precautionary principle" seems to me to be the epitomy of "NIMBY" " not it my backyard" which leads to the "Banana" principle "Build Absolutely Nothing Anywhere Near Anything." Not that it's wrong, but water and air are not "safe" in certain circustances: Query: shou ld we stop drinking water and breathing air? That's what the "Preca utionary Principle" would imply, unless we can be absolutery sure and ceriain that neither are harmful. (O2 at hyperbaric pressures f or more than 4 hours has toxicity -- see the Navy Diving Tables; hypoxia , I doubt anyone who has taken a Basic Life Support Course would doubt; high oxygen pO2s in premature neonates can result in serious damage to the eyes, and prolonged O2 in anyone can cause severe lung injuries). ; Persons with a certain "hyperdipsia" of water (a potentially fatal psyc hologcal condition) can dilute out the electrolytes in their serum, resul ting in serious cardiac and brain toxicity (ill-advised use of certain cath artics in childhood ingestion poisonings has had the same regretable result ). I suggest on a medical basis that stopping breathing air would result in fatal brain hypoxic damage within 5 minutes and that failin g to be able to drink water would result in fatal issues in 3-5 days. ;

"Is cyanide more toxic that water?" If the cyanide is a a proper co ntainer and stored in a proper exhaust hood, or if you were dropped from a helicopter into the middle of Lake Erie in December, which is more toxi c?

To answer the question, "Why do all of us eventually die?" We hav e to look at the fact that we are oxygen breathers and that this inevitably leads to formation of reactive oxygen species within cells, eventuating either necrosis or apotosis, and cell death and when this happens in too great of numbers, it cannot be survived.

As always, we agree to disagree. And as I have said for ages, M SDSs are a VERY, VERY poor source of information. Go to all of th e resources avalable to anyone, such as from the Specialized Information System of the National Library of Medicine: http:/nlm.nih.gov

Yes, the more we know about chemical exposures, the better off we'll be . But even in foods (without any contaminants), we can be exposed to millions of chemicals over a lifetime. In the end, all life i s chemical. As the Good Doctor Harry has said, being a chemist im plies chemical exposure. It does not mean that anyone should ever b e overexposed. So whatever any and all of do, let's do our best t o prevent overexposure.

The best thing in the world is to find a worthy adversary, even if most o f the time we're on the same page.

Respectfully,

Alan
Alan H. Hall, M.D.

Date: Sat, 12 Jun 2010 09:48:15 -0400
From: ACTSNYC**At_Symbol_Here**CS.COM
Subject: Re: [DCHAS-L] toxicity question
To: DCHAS-L**At_Symbol_Here**LIST.UVM.EDU

I want to than k Alan for his excellent answers. At first it sounded like people w ere asking about toxicity as if it could be measured by the LD & LC50 s, which of course it can't. These test will tell you if it can k ill or seriously damage animals (and presumably you) immediately by skin or eye contact, inhalation or ingestion. That's useful, but many carcinogens, including powdered asbestos, won't harm any animals in the two-week long LD & LC50 tests.

And the route it takes to get into your body is important. For example, ingesting mineral oil just gives you the Aztec two-step. Inhaling it can cause lipoid pne umonia and death. Local 802 in NYC had three cases at one time of t his pneumonia in musicians in a Broadway show that was using too much theat rical fog!

So this toxicity question is far more complicated. ; And the most important thing to remember is only a tiny fraction of the chemicals you use have been studied for chronic hazards. CAS regis tered it's 50 millionth chemical on Sept 7, 2009. About 900 chemi cals worldwide have been fully evaluated for cancer effects, and cancer i s just one of MANY possible chronic outcomes. We know squat about m ost chemicals, even some common ones and many "natural" ones which should not be assumed safe.

This is why the EU's Precautionary Principle i s so important. If you don't know what it will do to you long term , don't get into intimate contact with it. And many of you have students and workers who could be pregnant. These women should not be expose d to any chemical unless it has been determined that the substance cannot c ause birth defects, fetal toxicity, developmental defects or delays, or a number of other complications. And that, my friends, is th e case with just about ALL of the chemicals we use.

So turn on the hood and glove up. It's good lab practice anyway. T he answer is simple: no one can be harmed by a chemical to which they were not exposed.

The cavalry is coming in the form of the Global Harmoni zation System for MSDSs (to be called Safety Data Sheets). GHS has already been adopted by the EU and proposed by OSHA for adoption here. ; This GHS SDS has a toxicity section with 10 blanks for assorted acute a nd chronic tests. When a test has been done, the data must be rep orted. When the test has not been done, the only acceptable answe r in that blank is "no data available." We should soon be able to g lance down the list and see which tests have been done and which not.
This SDS feature will make my training for Hazcom and the Lab Standard so much easier!

And hopefully, this also will end the manufacturer's practice of using misleading statements on their MSDSs. For exampl e, they love to say their chemical is "not listed as a carcinogen by IARC , NTP or OSHA" which almost invariably means there is no data.

Mon ona Rossol

In a message dated 6/12/2010 6:18:11 AM Eastern Daylight Time, ahalltoxic**At_Symbol_Here**MSN.COM writes:

Are you asking about ACUTE toxi city? LD50's/LC50's/ED50's can basically only deal with this. ;

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