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Date: Tue, 11 May 2010 13:25:14 -0400
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: James DeNoble <James.DeNoble**At_Symbol_Here**DEP.STATE.NJ.US>
Subject: Re: 3 re: Hg response
Hi:
I'm a member of the Mercury work group at the NJ Department of Environmenta
l protection. The last two reference concentrations are quite low.
Ambient Hg concentrations in industrial areas can often be above 10 ng/m3,
and in the open ocean, Slemr et al identified levels in xs of 3ng/m3.
Could you provide the complete references cited so we could followup on
the basis and background of such low Hg concentration numbers. Thank you,
James P. De Noble MS
Bureau of Case Management
Site Remediation Program
New Jersey Department of Environmental Protection
>>> aaj**At_Symbol_Here**FORCE.DK 5/11/2010 8:23 AM >>>
The evaporation rate of mercury is fast (4 times butyl acetate)! The
vapours are heavy and will concentrate more at the floor. The vapours will
penetrate the blood-brain and the blood-placenta barriers as methyl
mercury do; thus a special risk for pregnant women.
It is correct that 5 mg Hg will not produce deadly concentrations in an
average room but easily higher concentrations than many establish limit
values (see table):
Tabel: Limit values in North america for mercury air exposures (Caravati
et al., 2008; Richardson et al., 2009; a.o.).
Air concentration (mg/m3)
Explanation
Authority
10
Immediately Dangerous to Life and Health (IDLH) (30 min)
NIOSH
0,5
Limit value for short-term exposures
WHO
0,1
Permissible Exposure Limit (PEL-TWA)
OSHA
0,05
Time-weighed average concentration (TWA)
NIOSH
0,025
Threshold Limit Value (TLV)
ACGIH
0,03
Recommended concentration after commercial cleaning
ATSDR
0,001
Recommended inhalation zone limit in homes after spill
ATSDR
0,0018
Reference Exposure Level (REL), (1 hour)
CalEPA
0,0003
Reference Concentration (RfC)
USEPA
0,0002
Minimum Risk Level (MRL)
ATSDR
0,00006
Reference Exposure Level (REL), long term concentration
Health Canada
0,00003
Reference Exposure Level (REL), long term concentration
CalEPA
Yours truly,
Allan Astrup Jensen
Technical Vice President
Secretariat for Metrology, Chemical analysis and Management Systems
FORCE Technology, Br=F8ndby
Park All=E9 345
2605 Br=F8ndby
Denmark
Phone: +45 43 26 70 00
Direct: +45 43 26 70 81
Mobile: +45 40 94 10 22
Fax: +45 43 26 70 11
e-mail: aaj**At_Symbol_Here**force.dk
www: www.forcetechnology.com
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________________________________
From: DCHAS-L Discussion List [mailto:DCHAS-L**At_Symbol_Here**list.uvm.edu] On Behalf Of
Ben Ruekberg
Sent: 11. maj 2010 13:43
To: DCHAS-L**At_Symbol_Here**LIST.UVM.EDU
Subject: Re: [DCHAS-L] 3 re: Hg response
Not wishing to be disputatious concerning the hazards of mercury,
nonetheless, I think before worrying about the saturation vapor pressure
of mercury, I suspect that one should also consider the rate of evaporation
of mercury as well. I don't know what it is, but were it all that
significant people would probably have to have been refilling McLoed
gauges with some frequency. In fact, I don't recall that ever being
necessary, nor do I recall finding significant amounts of mercury in the
Nitrogen traps of vacuum systems under normal circumstances. Given that
most rooms have reasonable air exchange, I suspect that rooms seldom reach
saturation.
To refer to the example of 5 mg of mercury reaching the saturation
concentration of 15 mg m^-3, one would be dealing with a room with a
volume of 1/3 m^3, an unusually small room. A 20' X 20' X 10' room would
hold (at saturation, with no air exchange) ~ 1.6 g of mercury, a mere
drop, but if a drop of mercury evaporated at a significant rate an amount
that might be noticeable.
What I am suggesting is that the rate of evaporation might be more
important than the saturation vapor pressure and may reduce the hazard (at
least for the short term) and that one might not need to be overly
alarmed.
Thank you,
Ben
________________________________
From: DCHAS-L Discussion List [mailto:DCHAS-L**At_Symbol_Here**LIST.UVM.EDU] On Behalf Of
List Moderator
Sent: Tuesday, May 11, 2010 7:16 AM
To: DCHAS-L**At_Symbol_Here**LIST.UVM.EDU
Subject: Re: [DCHAS-L] 3 re: Hg response
From: "Allan Astrup Jensen"
Date: May 11, 2010 5:26:29 AM EDT
Subject: RE: [DCHAS-L] 3 re: Hg response
Please, don't underestimate the danger of mercury vapour!
Mercury vapour is dangerous, and it is difficult to clean up indoor spills
completely. Even the 5 mg Hg from a crushed light bulb indoors can create
dangerous air concentrations, as many publications have shown. The
saturated air concentration at room temperature is about 15 mg Hg/m3. That
concentration is 500 times higher than the TLV, and such exposures have
resulted in serious intoxications.
Yours truly,
Allan Astrup Jensen
Technical Vice President
Secretariat for Metrology, Chemical analysis and Management Systems
FORCE Technology, Br=F8ndby
Park All=E9 345
2605 Br=F8ndby
Denmark
Phone: +45 43 26 70 00
Direct: +45 43 26 70 81
Mobile: +45 40 94 10 22
Fax: +45 43 26 70 11
e-mail: aaj**At_Symbol_Here**force.dk
www: www.forcetechnology.com
*************************************************************************
This email and any files transmitted with it may contain confidential
information intended for the addressee(s) only. The information is not to
be
surrendered or copied to unauthorised persons. If you have received
this communication in error, please notify us immediately by email at:
info**At_Symbol_Here**forcetechnology.com
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