Date: Thu, 14 Oct 2010 05:44:29 -0500
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: "Long, Don" <don.long**At_Symbol_Here**WGINT.COM>
Subject: Re: Science Education & Safety
Comments: To: chemsafety**At_Symbol_Here**
In-Reply-To: A<2113568020.826572.1287002843070.JavaMail.root**At_Symbol_Here**vznit170074>
One would think that if a chemical has it's own OSHA standard (in this case 3), then it probably has some inherent dangers attached to it. See 29 CFR 1910.1052, 1915.1052, 1926.1152 as well as OSHA Publication 3144-06R, 2003. A few good bits of info concerning DCM...
The thing to remember about OSHA standards is the fact that words such as "should", "suggested" and "not recommended" turn into "will", "shall" and "shall not" as far the law is concerned.
Don A. Long 
Southwest Research Institute Laboratory 
Pine Bluff Chemical Agent Disposal Facility 
PO Box 20130 
White Hall, AR  71612 

-----Original Message-----
From: DCHAS-L Discussion List [mailto:DCHAS-L**At_Symbol_Here**LIST.UVM.EDU]On Behalf Of Jay A. Young
Sent: Wednesday, October 13, 2010 3:47 PM
To: DCHAS-L**At_Symbol_Here**LIST.UVM.EDU
Subject: Re: [DCHAS-L] Science Education & Safety

You ask " What exactly is the problem with DCM?"
Answer: To learn the hazardous properties of a hazardous chemical, go to the references.  Outstanding authorities include the Documentation Volume published by the ACGIH, and Patty's Toxicology, a multi volume work published by Wiley.
Wikipedia and other stuff you can find on the internet--including even what is reported  in the DCHAS  e-mails--is not necessarily reliable.
You may object that Patty sure costs a lot of money, and so does that ACGIH publication, to say nothing of the time spent in finding and reading the information aout a chemical in these references.  
I reply that the biggest problem in chemical safety today is trying to get by on the cheap , spending as little money and time as one can get away with--and ending up with  ignorance and therefore, vunerability to a serious "accident" (which could have been prevented if you and others had spent the required time and money).
Jay Young

Oct 11, 2010 05:48:05 AM, DCHAS-L**At_Symbol_Here** wrote:

>I have an undergrad. lab experiment that uses dichloromethane to extract caffeine, 
>but hadn't thought of changing the solvent. This interesting discussion raises 
>the question of whether there is a "safety series" of solvents, much like 
>the elutropic series. What exactly is the problem with DCM? Is it safer or more 
>environmentally friendly (not necessarily the same thing) to replace 1 mL of one 
>solvent with xx mL of another? What about volatility? Should David replace the 
>hexane in his fries experiment with e.g. heptane, as we have done in the research 
>lab? Does price enter into the "value" of a solvent?
>On another note, I have recently been involved in assessing chemicals around 
>a pregnant student. I googled "teratogen" and found many sites that quoted 
>ethanol and dilantin and a few other prominent examples. Does anyone know if there 
>is a more complete list?
>Lastly, I was surprised to find dilantin on the list, especially since we have 
>another experiment in this class in which students make dilantin which has run for 
>years uneventfully (ignorance is bliss). Does anyone know what level of exposure 
>to dilantin is required to exert an effect? Should I worry about the (remote but 
>not inconceivable) possibility that a student in this class is pregnant? My feeling 
>is that the chances of successful synthesis X pregnancy likelihood X likelihood 
>of actually absorbing an adequate dose is pretty remote, when compared to e.g. alcohol 
>exposure for students. I can certainly warn students, but do not want mass hysteria. 
> I would appreciate any expertise.
>I look forward to continuing to read the excellent posts to this list: keep 
>up the great work!
>Best wishes, 
>On Sat, 9 Oct 2010 07:41:52 -0700
> DAVID KATZ < dakatz45**At_Symbol_Here**MSN.COM> wrote:
>> I did a quick and dirty web search for a caffeine extraction that does 
>not use dichloromethane. I found this   
>class="parsedLink" target="_blank"> It is by John Thomson at Lane Community College, Eugene, 
>> I have not tried this procedure and I would be curious to know how well 
>it works.
>> I do not know the scale at which the class at your university performs 
>this experiment, macroscale, small scale, semi-micro, or micro. That will also 
>affect the extraction solvent used. For semi-micro scale or microscale procedures, 
>I agree with Ernie Lippert that students must learn how to work with chemicals such 
>as dichloromethane safely. That includes the generation of only small quantities 
>of waste product. 
>> In another experiment, I have my class extracting the fat from potato chips 
>and French fries. Starting with 5 g of chips or 10 g of French fries in a 125-mL 
>flask, I have switched the solvent from dichloromethane to hexane and use several 
>rinsings of 10 mL or less. The solvent is disposed of in a waste bottle and the 
>chips or fries which are only slightly damp with solvent, in the flask, are dried 
>in a water bath under the hood. The fat content is determined by the loss in mass. 
> We get good results.
>> David A. Katz 
>Paul Harrison
>Associate Professor of Chemistry
>Department of Chemistry and Chemical Biology
>McMaster University
>1280 Main St. W., Hamilton, ON, L8S 4M1, Canada
>Phone: (905)525-9140 ext. 27290; FAX: (905)522-2509


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