Date: Fri, 6 Mar 2009 07:30:58 -0500
Reply-To: brian.spears**At_Symbol_Here**DOWCORNING.COM
Sender: DCHAS-L Discussion List <DCHAS-L**At_Symbol_Here**LIST.UVM.EDU>
From: brian.spears**At_Symbol_Here**DOWCORNING.COM
Subject: Re: Amorphous silicone dioxide silica
Comments: To: Paul.Dover**At_Symbol_Here**PHARM.MONASH.EDU.AU
In-Reply-To: <89907EA1DCFB7548A431C13A270F9DD506B16A59**At_Symbol_Here**prk-exch-01.vcp.local>

Paul -
There are two distinct types of silica, crystalline and amorphous silica.  
They differ significantly in the health effects they cause when inhaled.  B
oth crystalline silica and amorphous silica incite pulmonary inflammation, 
but significantly, only inhalation of crystalline silica ultimately leads t
o the development of pulmonary fibrosis (i.e. silicosis).  It is unclear wh
y there is such a difference in the pathological outcome.  Possibly due to 
the physical properties of amorphous and crystalline silica.  When inhaled 
crystalline silica particles are ingested by alveolar macrophages, the macr
ophages are activated and damaged, resulting in ongoing injury and ultimate
ly leading to the development of silicosis.  In contrast, amorphous form of
 silica has a far larger surface area and hence a greater relative solubili
ty within the lung, enabling it to be cleared more easily following inhalat

So back to your original question - I would not have an issue with the 25 k
g containers versus the 1 kg container - as long as it is amorphous silica 
and the handling is not generating a significant exposure to nuisance dust.

Best Regards,

Brian M. Spears, CIH, CSP, CHMM
Associate Industrial Hygiene Specialist

Safe Work IS Our Job

Dow Corning Corporation
4770 Highway 42 East
Carrollton, KY 41008
office:  (502) 732-2726 
mobile:  (502) 682-8593

-----Original Message-----
From: DCHAS-L Discussion List [mailto:DCHAS-L**At_Symbol_Here**] On Behalf Of Pa
ul Dover
Sent: Friday, March 06, 2009 2:11 AM
To: DCHAS-L**At_Symbol_Here**LIST.UVM.EDU
Subject: [DCHAS-L] Amorphous silicone dioxide silica

G'day all, 

Can I get some opinions/advice please?
Our HOD got 25kg drums of this stuff for each lab, Davisil LC60A 40-63
(um) LOW to be precise.
We just had an OHS inspection and the consultant was unimpressed and
suggested in future we get 1kg containers. We used to do this, but the
HOD noted cost 25kg was only three times cost of a 1kg container...and
we go through it.
Anyway, in lieu of that we were told risk assessments, SOP for transfer,
etc., required. No argument from me, silicosis is a nasty thing.
I call up the MSDS and to my great surprise it is Hazard alert: NIL, 
Non Hazardous Substance, Non Dangerous Goods.

Smug head of department feels vindicated in his choice to get 25kg drums
of the stuff. I'm not so sure.

I'll still get risk assessment and SOP, but what do I say next time he
wants to order in bulk!?

Cheers, Paul

Paul Dover
Resources Manager
Medicinal Chemistry and Drug Action
Monash Institute of Pharmaceutical Sciences
Monash University (Parkville Campus)
381 Royal Parade, Parkville
Victoria, 3052. Australia

Phone: +61 3 9903 9551
Fax:   +61 3 9903 9143

Email: Paul.Dover**At_Symbol_Here**

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