From: scvax@kuhub.cc.ukans.edu
Newsgroups: alt.great-lakes
Subject: Re: Pollution special
Date: 13 Aug 92 22:38:08 CDT
Organization: University of Kansas Academic Computing Services

In article <1992Aug13.190631.995@i88.isc.com>, jeq@i88.isc.com 
     (Jonathan E. Quist) writes:
> In article <scott.713651342@origin> scott@origin.life.uiuc.edu 
   (Scott Howard) writes:
>>Three thoughts on the fantasy clean-up idea of
>>using bacteria to break down PCBs in the clays and
>>soils on the lake bottom:
> Fantasy?  Why is that?  Ever hear of "bioremediation"?
> A company in my town just used that to clean up the site of a
> leaking underground oil tank.

The sorts of chemistry involved in the bioremediaton of oil spills (mostly
ALIPHATIC HYDROcarbons) and PCB/PBB (polyHALOGENATED AROMATIC compounds) 
are not that closely related.  Also the PCB/PBB compounds could very well be
toxic in the parts-per-BILLION range, the oil spill in your town will not 
need to be cleaned to anywhere near this level to be rendered environmentally 
innocuous.

The PCB/PBB sort of compounds have three strikes against them from an
environmental standpoint:

  1. Toxicity - at low concentrations
  2. Stability - these things just don't go away via. natural mechanisms
  3. Lipophilicity - (fat solubility)  the fat stores on fish and other 
                     animals act like sponges for these compounds which
                     increase EFFECTIVE exposure levels dramatically. 

  (DDT, Dioxin, et al.  also fit this profile.)

>>The breakdown products of PCBs are likely to be
>>just as toxic as the PCBs themselves, and even more
>>resistant to bio-degradation.

I have to believe that ANY biotransformation would improve situation.  Its
hard to think of anything that could be done to make these things both more
toxic AND more stable (again, doing something about any one of the three
criteria listed above would go a long way to take care of the problem).

>>The sediment is too cold in Michigan and Superior for such 
>>bacteria to grow.

I dunno.  Any bug that could be persuaded to eat PBB could probably be
pestered into living a few degrees below its optimal temperature :) .

>>Think people howl about genetically engineered strawberries?
>>Just wait till someone tries to release enough super-bugs
>>to inoculate a Great Lake!
> 
> If the bacteria involved feeds on PCBs and nothing else, what's the
> problem?  The colony will grow and thrive until the food runs out.
> Then it ceases to exist.
> 
> Am I missing something very basic here?

Possibly.  I don't think you'll find a bug that eats PCB's in a food sense,
but hope to engineer something that can deal with them if they're present
in its environment. PBB/PCB's would be an very poor food source for no 
other reason than their relative concentrations are so low.  Because of this
fact, you would probably have to FLOOD the area with these bacteria to have
a real benefit. 

One minor nit I have with the PBS special (and other sorts of "pop" environ-
mentalism) is the tendency to "go off half cocked" in drawing the cause and
effect relationship between the troubles with the wildlife in the lakes and
a particular chemical.  In the three lab studies that were in Wednesday's
show, all of the test organisms (children of fish eating humans, salmon fed
rats and baby fish) were exposed to the entire ENVIRONMENT of the lake.  
The human offspring by the maternal ingestion of fish, rats by eating the 
salmon and the fish from the yolk created by the mother fish.  Can anyone have
any idea how many thousand chemical compounds (natural and otherwise) these 
animals were exposed to.  There could very well be a hundred double-blind, 
controlled studies showing these effects from chronic exposure to low-level
PBB/PCB's alone, but they made no mention of them. (if I weren't in the 
middle of a dissertation, I'd hit the library (some more) and try to find 
this out for myself).  Again, there's little doubt that the PCB/PBB contam-
ination is bad news, but it would be a real mistake to go after the wrong
villain. 
 
> Jonathan E. Quist                           INTERACTIVE Systems Corporation
> jeq@i88.isc.com  '71 CL450-K4 "Gleep", DoD #094        Naperville, IL

With apologies for the length of this post,

Dave Huhta                   huhta@phys31.phsx.ukans.edu 
Dept. of Biochemistry        scvax@kuhub.cc.ukans.edu
University of Kansas

p.s.  both of my grandfathers spent significant portions of their adult lives
      as commerical fishermen on Lake Superior.  My parents, naturally, ate a
      lot of the "bounty of the lake". Luckily it did not seem to [twitch] 
      affect their offspring [twitch].  :)