permaculture

["Scott Pittman" <scott@permaculture.org>]

Thanks Larry I posted without having the input of your thoughtful post.
Scott

"Another world is not only possible, she is on her way. 
On a quiet day, I can hear her breathing." 
~Arundhati Roy


-----Original Message-----
From: permaculture-bounces@lists.ibiblio.org
[mailto:permaculture-bounces@lists.ibiblio.org] On Behalf Of Frances and
David
Sent: Thursday, November 08, 2012 9:09 PM
To: permaculture
Subject: Re: [permaculture] Fwd: Re: Highest use for tires?

Very appreciative of this topic of discussion.  Thanks to all participating.
We were looking into this question ourselves, and personally, the idea of 
using tires for 'earth ship' type homes in a climate with as much rain as 
the pacific north west has in winter, does not entice us.
Frances


-----Original Message----- 
From: Lawrence London
Sent: Thursday, November 08, 2012 1:57 PM
To: permaculture
Subject: [permaculture] Fwd: Re: Highest use for tires?

http://www.puyallup.wsu.edu/~linda%20chalker-scott/horticultural%20myths_fil
es/Myths/Rubber%20mulch.pdf

""Non-toxicity" of rubber mulch Current research at Bucknell University
indicates that rubber leachate
from car tires can kill entire aquatic communities of algae, zooplankton,
snails, and fish. At lower
concentrations, the leachates cause reproductive problems and precancerous
lesions. A similar study
exploring the use of tires as artificial reef substrates also found rubber
leachate to negatively affect the
survival of various seaweeds and phytoplankton. Marine and other saline
environments are less sensitive
to tire leachates, however, and the greatest threat of contamination
appears to be to freshwater habitats.
Part of the toxic nature of rubber leachate is due to its mineral content:
aluminum, cadmium, chromium,
copper, iron, magnesium, manganese, molybdenum, selenium, sulfur, and zinc
have all been identified in
laboratory and field leachates. If rubber products have been exposed to
contaminants during their useful lifetime, such as lead or other heavy
metals, they will adsorb these
metals and release them as well. Of these minerals, rubber contains very
high levels of zinc - as much as 2%
of the tire mass. A number of plant species, including landscape materials,
have been shown to
accumulate abnormally high levels of zinc sometimes to the point of death.
One USDA researcher who has
studied zinc and other metals in soils and plant materials for decades
strongly believes that ground
rubber should not be used "in any composting, or in any potting medium, or
casually dispersed on
agricultural or garden soils" because of zinc toxicity. Acidic soils and
aquatic systems are particularly
sensitive, since heavy metals and otherpositively charged elements are less
tightly bound to the soil and more
available to plant and animal uptake.
Rubber leachates are complex solutions. They include not only the minerals
and organic building blocks of rubber,
but also various plasticizers and accelerators used during the vulcanizing
process. In high enough concentrations,
some of these rubber leachates are known to be harmful to human health;
effects
of exposure range from skin and eye irritation to major organ damage and
even death. Long term exposure can lead to neurological damage,
carcinogenesis, and mutagenesis.
Some of these materials break down quickly, while others are known to
bioaccumulate. One of the more common rubber leachates is
2-mercaptobenzothiazole, a common accelerator
for rubber vulcanization. In addition to its known human health concerns,
it is highly persistent in
the environment and very toxic to aquatic organisms: its environmental
persistence may cause long-term
damage to aquatic environments constantly exposed to rubber leachates.
Another family of organic
leachates under scrutiny are the polyaromatic hydrocarbons (PAHs). These
compounds, used as rubber
softeners and fillers, have been repeatedly demonstrated to be toxic to
aquatic life. PAHs are released
continually into solution, and after two years in a laboratory test
leachates were shown to be even more
toxic than at the study's inception It is abundantly clear from the
scientific literature that rubber should
not be used as a landscape amendment or mulch. There is no question that
toxic substances leach
from rubber as it degrades, contaminating the soil, landscape plants, and
associated aquatic
systems. While recycling waste tires is an important issue to address, it
is not a solution to simply move the
problem to our landscapes and surface waters.
The Bottom Line
. Rubber mulch is not as effective as other organic mulch choices in
controlling weeds
. Rubber mulch is highly flammable and difficult to extinguish once it
is burning
. Rubber mulch is not permanent; like other organic substances, it
decomposes
. Rubber mulch is not non-toxic; it contains a number of metal and
organic contaminants with known environmental and/or human health effects

For more information, please visit Dr. Chalker-Scott's web page at
http://www.theinformedgardener.com.";

<>

https://www.sciencedirect.com/science/article/pii/S004565350400760X
"Car tires contain several water-soluble compounds that can leach into
water and have toxic effects on aquatic organisms. Due to tire wear, 10
000 tonnes of rubber particles end up along the Swedish roads every
year. This leads to a diffuse input of emissions of several compounds.
Emissions of polyaromatic hydrocarbons (PAHs) are of particular concern.
PAHs are ingredients of the high aromatic oil (HA oil) that is used in the
rubber
as a softener and as a filler. The exclusion of HA oils from car tires has
started,
and an environmental labeling of tires could make HA oils obsolete."
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