[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

Re: Static Magnetic Field G



                      RE>>Static Magnetic Field Gu                 5/10/96

These are static fields.  The numbers are in gauss units.

The counterpart limit for 60 Hz, from the TLVs, is 10 gauss.  Time varying
fields can induce current flows, the basis of the TLV, while 0 Hz fields do
not.  For 0 Hz fields, induced voltages occur during the ejection of the
blood, an fluid with ions, into the aorta (and other large vessels) at high
speed.  This induces a "magnetohydrodynamic" voltage that coincides with the t
wave of an EKG.  Magnetic interactions require change, either by changing the
field or by movement of charges as in blood flow.

--------------------------------------
Date: 5/9/96 6:24 PM
To: GORDON MILLER
From: radsafe@romulus.ehs.uiuc.edu
On   Wed, 08 May 1996 you wrote

>         Reply to:   RE>Static Magnetic Field Guidelines
> 
> More recent guidance can be found in International Commission on
Non-Ionizing
> Radiation Protection. "Guidelines on Limits of Exposure to Static Magnetic
> Fields," Health Phys. 66, 100-106 (1994).  ICNIRP specifies:
> 
> o	A 2000 gauss time-weighted average exposure criterion,
> 
> o	30 gauss as where metallic implants and tools can become hazardous,
> 
> o	10 gauss as where credit card stripes can be erased, and
> 
> o	5 gauss as the pacemaker/electronic implant warning criterion.
> 
> The 600 gauss limit was developed by Tom Tenforde, now with PNL, and I.  I
> actually calculated the number.  The background for the 600 gauss limit is
> found in G. C. Miller. "Exposure Guidelines for Magnetic Fields," J.
American
> Industrial Hygiene Association, 48, 957-968 (1987).
> 
> LLNL now uses the ICNIRP limit of 2000 gauss and I have written to the Chair
> of the Physical Agents TLV Committee advising them to adopt the 2000 gauss
> limit.
> 
> If there are further questions, please contact me at:
> 
> Internet: gordon.miller@quickmail.llnl.gov
> 
> Lawrence Livermore National Laboratory, P. O. Box 808  (L-289), Livermore,
CA 
> 94551-0808
> 
> Phone (510) 423-8036
> Fax (510) 423-1086
 
Is this 2000 Gauss or 2000 milli gauss?

Regards

 
Michelle Wakelam
Occupational Hygienist and 
Assistant Radiation Protection Officer
Occupational Health, Safety and Environment
Monash University, 
Wellington Road,
Clayton, Victoria, 3168
Australia
email: Michelle.Wakelam@ADM.monash.edu.au

------------------ RFC822 Header Follows ------------------
Received: by quickmail.llnl.gov with SMTP;9 May 1996 18:24:24 -0700
Received: from romulus.ehs.uiuc.edu (romulus.ehs.uiuc.edu [128.174.74.24]) by
postoffice.cso.uiuc.edu (8.6.12/8.6.12) with SMTP id UAA230794; Thu, 9 May
1996 20:11:58 -0500
Received: from localhost by romulus.ehs.uiuc.edu (NX5.67d/NeXT-2.0)
	id AA12386; Thu, 9 May 96 20:11:01 -0500
Date: Thu, 9 May 96 20:11:01 -0500
Message-Id: <11A168D10A4@its-admin1.cc.monash.edu.au>
Errors-To: melissa@romulus.ehs.uiuc.edu
Reply-To: radsafe@romulus.ehs.uiuc.edu
Originator: radsafe@romulus.ehs.uiuc.edu
Sender: radsafe@romulus.ehs.uiuc.edu
Precedence: bulk
From: Michelle Wakelam <Michelle.Wakelam@adm.monash.edu.au>
To: Multiple recipients of list <radsafe@romulus.ehs.uiuc.edu>
Subject: Re: Static Magnetic Field Gu
X-Listserver-Version: 6.0 -- UNIX ListServer by Anastasios Kotsikonas
X-Comment:  Radiation Safety Distribution List