Sanet,
The following is from Dr. Robert Rynk with BioCycle magazine,
formerly compost specialist with Cornell University and
University of Idaho, on the topic of presticide residues in compost.
The post is from the Compost Council email list.
The literature review article he refers to from a recent issue of
Compost Science & Utlization, which can be consulted for
information on occurence and degradation of pesticides during
composting.
Steve Diver
============================================
Date sent: Fri, 30 Jun 2000 10:50:28 -0400
From: Robert Rynk <rrynk@jgpress.com>
To: compost@compostingcouncil.org
Subject: Re: [USCC] Problems from clopyralid
Send reply to: compost@compostingcouncil.org
Several colleagues and I conducted a literature review on the
occurence and fate of pesticides during composting. Clopyralid was
not prominent in the papers that we reviewed. Nevertheless, in
general, with a few exceptions, after many analyses of composting
feedstocks and compost, via numerous research projects, few of the
target pesticides searched for were detected -- even in the raw
feedstocks. Less occurred in the composts. Exceptions were mostly
formerly-used organochlorine compounds, with chlordane being the most
conspicuous. Furthermore, those compounds that were detected occured
at reportedly low concentrations (low being arbitrarily defined in
most cases). In a relative sense, herbicides were rarely detected.
Only one study looked at the effect of herbicide residue in compost on
phytotoxicity (Bugbee and Saraceno). This study spiked compost with
2,4-D, dicamba and MCPP and then grew tomatoes in order to propose
plant-safe maximum allowable concentarions of these herbicides in
compost. Otherwise, except for perhaps a few compost-quality programs
such as Portland Metro's Earthwise, there are no guidelines for how
much herbicide residue or other pesticides generally are acceptable in
compost. Two studies took a conservative approach, using food product
standards as a benchmark for pesticide residue in compost. In one of
these studies (Miller et al.), only one sample out of 44 had any of
the target compounds in concentartionms above the food standard -- it
occured with only one compound, the herbicide atrazine. The second
study (Richard and Chadsey) found on ly chlordane exceeded the food
tolerance but remained at levels similar to background soil
concentrations. This says nothing about clorpyralid specifically
(except that it either wasn't found or wasn't searched for) but
suggests that pesticides residues are not a big concern IN GENERAL.
I suppose we cannot rule out herbicide residues as the cause of plants
damage from compost use. Usually, though, high salt levels or
phytrotoxic by-products of incomplete decomposition are the culprits.
It would be a shame to see regulations reguiring expensive screening
of composts for pesticides when they do not seem to be a big problem
in composts.
The literature review paper appeared in two parts in Compost Science &
Utilization, the Autumn 1999 and Winter 2000 issues (Occurrence,
Degradation, and Fate of Pesticides During Composting, by Buyuksonmez
et al). Other references noted are:
Bugbee, G.J. and R.A. Saraceno. 1994. Phytotoxicity of compost treated
with lawn herbicides containing 2,4-D, dicamba, and MCPP. Bull.
Environ. Contam. Toxicol., 52:606-611
Miller, T.L., R.R. Swager, and A.D. Adkins. 1992. Selected metal and
pesticide content of raw and mature compost samples from eleven
Illinois facilities. Illinois Department of Energy and Natural
Resources, Springfield, IL.
Richard, T. and M. Chadsey. 1989. Croton Point compost site
environmental monitoring program. Westchester County Solid waste
Division, White Plains, NY
RESRECYCLE@aol.com wrote:
> I am looking into the reported problems of some compost producers
> from the handling of grass clippings containing residues from Dow's
> Confront-brand lawn chemical. At least one state has told compost
> producers to not sell compost containing more than 0.03ppm
> clopyralid to greenhouses and to be cautious about recommending it
> for vegetables or pricey ornamentals. Have others "confronted" this
> problem?
>
> Jerry Powell
>
> __________________
> Resource Recycling
> P.O. Box 42270
> Portland, OR 97242-0270
> (503) 233-1305, 233-1356 (fax)
> www.resource-recycling.com (Web site)
-- Robert Rynk JG Press. Inc. 419 State Ave. Emmaus, PA 18049610-967-4135 fax: 610-967-1345 email: rrynk@jgpress.com
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