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Chronological Thread  
  • From: Bob <rmhoward@omninet.net.au>
  • To: permaculture <permaculture@franklin.oit.unc.edu>
  • Subject: Re: Plastic Contamination
  • Date: Tue, 20 Feb 2001 14:07:21 +0800




Randy wrote:

> Hello again:
>
> I am using large plastic tubs to transport water. I am
> not going to store water in them for any period of time. They have been
> rinsed with water inside and out, and allowed to sit exposed to the
> elements. How can I clean them to reduce the amount of plastic/ plasticizer
> contamination in the water? Would baking soda or rubbing alcohol work?

No! Alcohol would probably make matters worse. Presumably your plastic tubs
are made
from PVC (most are). On some plastic containers there is a recycling
indentation
indicating plastic class. You can check the kind of plastic by burning a
small sample
and noting the smell - not recommended unless you're interest in chemistry
exceeds
your interest in self preservation. PVC smells of chlorine - but burning PVC
produces
dioxins (highly toxic - most toxic small molecule known to humankind )

Exposure to sunlight causes plasticizers to leach out of PVC ( in new cars
this
results in that new car smell and the plasticizers sometimes condense on the
windscreen as a film along the base. When they leach out the plastic goes
hard and
brittle. Hence the harder and more brittle the container is the less
plasticizer
present. Plasticizers in soft PVC tubing (the kind used as coating for
electrical
wires) have been reported to leach out into the air and poison germinating
plants in
greenhouses. One plasticizer DEHP(diethylhexylpthalate) is widespread in the
environment and is detected in mid pacific samples along with DDT and other
persistent
pollutants. DEHP has been withdrawn from many uses in recent years.

Conclusion is
- check the plastic type
- use old containers
- whatever you do don't burn PVC

>
> There is another dillemna with contamination. I had a
> large order of compost delivered that I found to contain a large amount of
> plastic and (perhaps treated)wood waste. The company that I bought it from
> has been dicking around for quite a while. I am going to post an
> advertisement to give it to anyone who wants it for free, just to get it off
> my land. . . on the condition that it is not used with edibles. What kind of
> substances occur when soft and hard plastic are heated within a large
> compost pile? Is there a firm that I can send a sample to? How should I
> rehabilitate the land where it was located/ leaching?

Most shredded plastic is usually polyethylene ( i.e. shopping bags/ food
packaging)
this is pretty harmless stuff (contains only carbon and hydrogen) which needs
wood rot
fungi to break down. Polyurethane's could be a problem in a compost heap
urethane is
pretty toxic. Dioxins won't be produced by compost heap temperatures if there
is PVC
in the mix unless the heap catches fire - you need temperatures above 500deg C

>
> Also: What substances are commonly used to treat
> lumber, and what kind of diagnostics can be used to detect them in the soil?
> I would really appreciate any piece of mind you can provide.
>

Arsenic is the real meanie in treated timber and often contaminates sites
(not just
from treated timber but old cattle and sheep yards where arsenical dips were
used in
the 1950's). It's expensive to test commercially but there may be a home
based test
that can be used. Indian chemists are particularly good at coming up with
cheap
testing techniques I'd suggest a search through Environmental Toxicology
Abstracts at
your local University - I can't help I'm 400 kms from the nearest Uni.
Somebody else
on this list may have some ideas.

>
> Thank you,
> Donahuer@ols.net
>
>
>
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