Path: utzoo!mnetor!motto!ecijmm!ecicrl!clewis
From: clewis@ecicrl.UUCP
Newsgroups: can.general
Subject: Re: Attikamek-Montagnais Protest PCB Plan
Message-ID: <674@ecicrl.UUCP>
Date: 19 Sep 89 03:40:32 GMT
References: <2324@yunccn.UUCP> <620791816.24086@telly.on.ca> <1989Sep5.173937.24977@utzoo.uucp> <8328@looking.on.ca> <28908@watmath.waterloo.edu> <2484@dciem.dciem.dnd.ca> <1989Sep11.142805.862@eci386.uucp>
Reply-To: clewis@ecicrl.UUCP (Chris Lewis)
Organization: Elegant Communications Inc., Ferret Division, Toronto, Canada
Lines: 49

In article <1989Sep11.142805.862@eci386.uucp> clewis@eci386.UUCP (Chris Lewis) writes:
>In article <2484@dciem.dciem.dnd.ca> bpd@dretor.dciem.dnd.ca (Brian P. Dickson) writes:

>>I am afraid you are quite wrong. There is another chemical which has
>>rightly gained a bad reputation: dioxin. Dioxin will cause cancer on
>>contact, and is considered hazardous in any detectible concentration.
>>There is no acceptable level for dioxin - it is dangerous even at
>>one part per quadrillion (!). 

>Interesting:

>	2) The 1988 Fish Eating Guide (published by the MOE) considers
>	   1 part per trillion as the main threshold:

Oops, that's *20* parts per trillion.  Just checked again...
That's only 20,000 times higher than your figure.  Where'd you get
yours from?

[Incidentally, 2,3... TCDD is listed very explicitly as "acutely toxic to 
some lab animals".  Note the "some".  Leads one to believe that human
toxicity/teratogenic properties in man aren't completely understood, as they
are for, say, potassium cyanide.  Not that that makes any difference
to permissible limits - the wildlife in the environment are of importance
too!]

Similar thresholds:

	PCB: 2.0 parts/million
	MIREX: .5 parts/million
	DDT: 1 part/million (I think)
	Mercury: 1 part/millon

The book goes on to mention that the previous chemicals of concern
(DDT, Mirex and Mercury) have shown a steady and very significant
decrease over the last decade or two (particularly DDT), and mercury 
is now only dangerous in a few very restricted areas.  (Mirex is
only in the Great Lakes, below Niagara Falls NY I believe...)

(all of the above are generally cumulative.  The Ministry has tested
thousands of lakes including a sampling of all fish species of interest.
The concentrations are measured in the dorsal area of fish.  The
book is quite thick listing the relative safety of fish consumption
versus location, species, and fish size.  There are a surprising
number of areas that have problems with larger fish)
-- 
Chris Lewis, R.H. Lathwell & Associates: Elegant Communications Inc.
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