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Subject: Re: [DCHAS-L] "Read the SDS"

Date: Apr 12, 2018 21:29 UTC

Author: Monona Rossol <0000030664c37427-dmarc-request**At_Symbol_Here**LISTS.PRINCETON.EDU>

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Subject: [DCHAS-L] Chemical Safety headlines (15 articles)

Date: Apr 13, 2018 11:56 UTC

Author: DCHAS Membership Chair <membership**At_Symbol_Here**DCHAS.ORG>

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From: Alan Hall <oldeddoc**At_Symbol_Here**GMAIL.COM>

Subject: Re: [DCHAS-L] "Read the SDS"

Date: Apr 12, 2018 21:57 UTC

Reply-To: ACS Division of Chemical Health and Safety

In-Reply-To:  

Demystify: 

Et al,

Once I had an occasion to review the tox literature on dichloromethane (also known as methylene chloride) back to the late 1800s.

While there was a lot of litaturea round the 1980s about its metabloic conversion to carbon monoxide, except for one report of 2 patients who supposedly had carboxymethemoglobin levels rather high (and which did NOT correlate with their clinical symptoms), the main toxicity of this chemical is that it is a volatile chlorinated hydrocarbon which has general anesthetic properties. It was in fact used as a general anesthetic for many years. It was used as a obstetic general anesthesic agent in Germany until the 1950s. About as much carbon monoxide found in most exposure cases is not much greater than found in heavy smokers or in residents of certain areas with a lot of carbon monoxide air pollution.

The reason it was abandoned for this purpose was that the Therapeutic Index (TI) was too narrow, meaning that the dose which produced surgical anesthesia was so close to the dose that caused cessation of breathing and eventually death, were so close together that it was not safe to use.

As with many other volatile hydrocarbons once used as anesthetics, it is well off far behind us (I have formal training in anesthesiology).

As Monona points out, carbon tetrachloride has a somewhat different toxicological profile, and certainly when ingested in suicide attempts or when high-level inhalatione xposures occur, it can cause severe and sometimes fatal liver and renal toxicity.

Dichloromethane has, just as most compounds in this chemical class, the ability to cause severe defatting dermatitis which clinically resembles 2nd degree chemical burns from corrosive substances.

Frankly, I wish nobody ever used either of them again for any purpose, although carbon tet was non-flammable and widely used for fire suppression in the past.

Product substitution ought to make it such that a much les toxic compound is substituted for a much more toxic compound. Otherwise, there's absolutely no sense to it.

My 2 cents worth

Alan H. Hall, M.D.
Medical Toxicologist

On Thu, Apr 12, 2018 at 4:29 PM, Monona Rossol <0000030664c37427-dmarc-request**At_Symbol_Here**lists.princeton.edu> wrote:
Well, dichloromethane is not so much less toxic than carbon tet that you would notice. Carbon Tet is banned in consumer products primarily because it is synergistic with alcohol and associated with many fatalities. The proposal to ban dichloromethane was just delayed by Trump, but it metabolizes to form CO and is also associated with many fatalities. They are both IARC 2B carcinogens.

So the green substitute stuff just a hair less hairy.

No gold star for the Greenies.


Monona Rossol, M.S., M.F.A., Industrial Hygienist
President: Arts, Crafts & Theater Safety, Inc.
Safety Officer: Local USA829, IATSE
New York, NY 10012 212-777-0062



-----Original Message-----
From: TILAK CHANDRA <tilak.chandra**At_Symbol_Here**WISC.EDU>
To: DCHAS-L <DCHAS-L**At_Symbol_Here**PRINCETON.EDU>
Sent: Thu, Apr 12, 2018 12:46 pm
Subject: Re: [DCHAS-L] "Read the SDS"

Hi Monona:
I agree with you, however use of less toxic chemicals is also a component of green chemistry principles, see below.
https://www.acs.org/content/acs/en/greenchemistry/what-is-green-chemistry/principles/12-principles-of-green-chemistry.html
As an example, dichloromethane is much safer/less toxic than carbon tetrachloride if you use it as a solvent for the NBS based bromination reaction. Generally, carbon tetrachloride works very well for such brominations.
Regards,
Tilak
From: ACS Division of Chemical Health and Safety <DCHAS-L**At_Symbol_Here**PRINCETON.EDU> On Behalf Of Monona Rossol
Sent: Thursday, April 12, 2018 11:24 AM
To: DCHAS-L**At_Symbol_Here**PRINCETON.EDU
Subject: Re: [DCHAS-L] "Read the SDS"

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