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In today’s world, where yard trimmings are banned from many landfills,
composting is one of the only means for responsible stewardship. The recycling
and composting industries are worried that persistent herbicides, such as
clopyralid, might jeopardize the significant gains in public confidence
regarding organics recycling and compost markets. There is also a financial
element. Millions of dollars have been invested in many composting facilities
for the public and commercial companies to bring yard trimmings for composting,
and to purchase compost. At the Spokane Regional Compost facility, 25,000 cy
from 2000 remain unsold and clopyralid contamination in 2001 has prevented sale
of compost to the general public. At WSU, the cost from two years’ loss of
revenue, claims, bioassay and analytical testing, and additional labor has
totaled about $250,000.
The Washington Organics Recycling Council (WORC) is asking all composting
facilities to start performing bioassay growing trials to monitor for
clopyralid. These tests are much cheaper than chemical analysis. “If they do
find herbicide effects in their bioassays, we recommend they follow up with
chemical tests,” said Jeff Gage, WORC president and a member of the board of
directors of the U.S. Composting Council. Gage said Washington has about 30
licensed public and private composting facilities.
What should be done to protect the recycling and composting communities from
inadvertent contamination by persistent herbicides, and whose responsibility is
it? Voluntary removal of products locally, as in Spokane, is one option.
Restricting the sale on a county or state basis is another. A third option is
controlling the feedstocks that enter a composting facility. However, this can
be difficult as there is often a disconnect between the applicator of the lawn
care services and the service of picking up lawn clippings and distributing them
to appropriate treatment sites. With turf applications, the ultimate solution is
to grass cycle, a wise option in any case.
One fact is apparent — relying on the herbicide label restrictions is not
enough. Herbicides from feedstocks treated with clopyralid can remain in compost
for sale to the public, even though the label may have been followed. The public
is often not aware that the intent to have weed-free lawns and crops may have
hidden dangers from persistent herbicides.
Public utilities in Washington and Oregon have sent a letter to the U.S.
Environmental Protection Agency urging them to reconsider its criteria for
registration and re-registration of herbicides to include the ultimate end use
of urban yard trimmings, food scraps, and agricultural wastes (see “Composting
View” in this issue). This letter emphasizes that the fate of residual
herbicides must be tested in the normal 60 to 90 day composting cycle to assure
that no residual herbicide remains. Some facilities compost for even shorter
periods of time. The letter emphasizes that the ultimate responsibility in
dealing with clopyralid residues should not be on the compost producers, but on
the manufacturer of herbicide-containing products.
Should those registering persistent herbicides give more consideration to the
potential end use of residues treated with their products? With composting now
being a standard practice of recycling, should not the entire waste reduction
and pesticide industries assure that chemicals applied to composting feedstocks
be compatible with the potential end uses of the compost? Better awareness and
communication between chemical suppliers, lawn care providers, homeowners, other
chemical users, and the composting community is needed to recognize the risks of
using persistent herbicides. Those who collect, haul and process feedstocks for
composting don’t always know the history of the feedstocks.
THE IMPLICATIONS
Regardless of the pesticide registration debate, composting facilities should
take note of the possibility that persistent herbicides can endure in compost at
damaging levels. So far, clopyralid and picloram are the only herbicides that
been implicated, and only at a few facilities. Nevertheless, a few prudent
practices might avoid big problems. Facility operators should become familiar
with sources of feedstocks and inquire whether persistent herbicides have been
used. A bioassay should be conducted on all feedstocks suspected of being
treated with clopyralid, especially grass clippings, as well as the finished
compost. If symptoms of herbicide damage show, bioassays should be followed up
with analytical tests. It is important to check for salinity and maturity to
verify that the symptoms reflect only herbicide damage.
As for the big picture, regulatory agencies need to reexamine the criteria used
in considering the registration and reregistration of persistent herbicides to
include all possible end uses of plant residuals. Herbicide manufacturers must
recognize that the persistence of herbicides is a critical concern to all end
uses of plant residuals, including recycling and composting. The composting
industry urges herbicide manufacturers to reexamine the chemistry and
formulation of existing and new herbicides for persistence in the environment so
that recycling and composting are not at risk.
David Bezdicek and Mary Fauci are with the Department of Crops and Soil Sciences
at WSU in Pullman; Dan Caldwell and Rick Finch are with the Department of Animal
Sciences at WSU and manage and operate the composting facility; Jessie Lang is
Recycling Coordinator for the City of Spokane, Spokane Regional Solid Waste
System.
REFERENCES
Bezdicek, David, Mary Fauci, Dan Caldwell, and Rick Finch. 2000. Compost
quality-new threats from persistent herbicides.
Agrichemical and Environmental News. 174: 9-13.
Buyuksonmez, Fatih, Robert Rynk, Thomas F. Hess, and Edward Bechinski. 1999
(Part I), 2000 (Part II). Occurrence, degradation and fate of pesticides during
composting. Compost Science and Utilization. 7(4):66-82 (Part I), 8(1):61-81
(Part II):
Dow, 1997. Clopyralid, A North American Technical Profile. Dow AgroSciences,
Indianapolis, IN.
Miltner, Eric and Gwen Stahnke, 2000. Turfgrass clippings – a bagful of lawn 
and
turf issues. 2000. Agrichemical and Environmental News. 174: 6-8.
Vandervoort, C., M. J. Zabik, B. Branham, and D. W. Lickfeldt. 1997. Fate of
selected pesticides applied to turfgrass: effect of composting on residues.
Bull. Environ. Contam. Toxicol. 58:38-45.
WSDA. 2000. WSDA Case 003S-00 on Spokane compost incident, R. Scott Nelson.


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heidi larson




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