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Re: Compost Contaminant?



ComCouncil@aol.com wrote:
 
> Is anyone aware of a material known as: bis (2-ethyl hexyl) phthalate ?

Yes, this is commonly known as DOP (di-octylphthallate). It is the most 
common plasticizer used to soften rigid PVC (polyvinyl chloride) to make 
"flexible vinyl"

> Is this a substance that can and/or will contaminate finished compost
> product?

I'm not sure about it's stability in compost, but it is one of many, many 
chemicals that have been implicated as "estrogen mimickers." It would be 
an excellent choice to use to study breakdown during composting, because 
it is so widely distributed, and it is analogous to the other phthallates. 
Also, it is easy to detect, and it's primary decomposition products are 
known. DOP is a significant contributer to that "new car smell."

My guess is that some soil microbes can eat it, but since it does not 
occur naturally, one would expect the concentration of such microbes to be 
quite low. However, insofar as a soil microbe was recently observed to be 
eating PCB's (much harder to decompose), my guess is that it can be 
decomposed, though perhaps by adnormal microbes for a compost pile.

> Can it be minimized?  Eliminated?

Good questions. By itself, it would burn cleanly, but in the form of 
vinyl, it is not advisable to burn it unless one has scrubbers on the 
combustion process to remove the byproduct HCl.

It is not essential for flexible vinyl, and there are available 
substitutes. I don't know that the substitutes are safer, but some of them 
probably are. Remember, most consumers don't want fungus or bacteria 
eating their vinyl.

A larger question from my perspective, is why PVC is still legal. It 
raises havoc for plastics recycling.
> 
> Any thoughts would be very appreciated. 
There was a great deal of R&D on sytemic DOP from flexible vinyl medical 
tubing (catheters, IV's, etc. I don't know what came of this R&D; there 
was talk of banning DOP in such applications. It's certainly not acutely 
toxic.

...Roger Faulkner