[USCC] Poison Oak in Compost
Matthew Cotton
matt at mattcotton.com
Thu Apr 9 14:13:46 CDT 2009
Jack -
This is an issue that comes up from time to time with compost. Bob
Rynk did a Q&A column on this for BioCycle back in 2000 (see below)
and found that the active chemical in Poison Oak/Ivy/Sumac (Urushiol)
is pretty hardy stuff. No definitive fate of Urushiol in compost
studies that I've heard of.
If you live around the stuff you know that it can and does get on
anything, tools, clothes, dogs, etc. It can also take days to present
symptoms. I'm sure that some of this material finds it's way into
commercial compost piles and I imagine it is at least somewhat
degraded by the composting process. However, as Bob's article
cautions against burning, I would be very careful about composting
it. I wouldn't and don't compost it at home; I know of at least one
reliable case of a colleague inhaling compost with poison oak in it
(at a farm-scale facility) and internalizing the poison resulting in
many unpleasant injections and time off. I also imagine that in a
typical commercial facility it gets diluted quite substantially with
other materials.
Hope this is useful. I'm scratching a little already.
Matthew Cotton
Integrated Waste Management Consulting, LLC
19375 Lake City Road
Nevada City, CA 95959
(530) 265-4560
Fax (530) 265-4547
matt at mattcotton.com
www.mattcotton.com
A Reader's Q&A column in BioCycle (May 2000) discussed the possible
fate of the poison ivy toxin during composting. I have pasted the Q&A
text below. It seems consistent with the comments submitted so far.
************************************************************************
***
Q. What is the fate of poison ivy in a composting system? The owners
of a large pile of brush have asked to burn the pile. They say
composting will not destroy the oils in the plant. Will burning pose
even a greater threat through airborne contamination?
A. While there is a great deal of information available about the
poison ivy plant, and the rash that it causes, there is little
guidance available about how to dispose of it. Fact sheets, books,
and web pages caution us not to touch poison ivy, and not to burn it,
but they stop short of
recommending how to dispose of poison ivy vegetation. Burning poison
ivy is a bad idea (except under controlled conditions). People have
developed severe reactions from breathing in smoke particles from
burning vines. Burying poison ivy in the ground and putting it in the
trash have been suggested
as disposal methods but these alternatives have obvious
disadvantages, especially if poison ivy is mixed with large
quantities of yard trimmings. Apparently, there isnít a good method,
or at least a certain method of safely disposing of poison ivy.
Intuitively, some poison ivy experts and composting practitioners
guess that the poison ivy toxin decomposes during composting but
there are plenty of ìifsî and ìmaybesî in their statements. Outside
of the compost pile, there is ample evidence that the poison ivy
toxin can persist and remain potent
for years. Unfortunately, there isnít a clear cut answer about the
fate of poison ivy during composting. Here is what we do know.
The rash that occurs from poison ivy, poison oak and poison sumac
is caused by a family of organic compounds called urushiol
(pronounced oo-roo shee-ohl , or you-ROO-she-ol, depending whether
you read it in the north or south). Urushiol includes several organic
molecules with an aromatic structure,
categorized as catechols. The literature on poison ivy also refers to
the toxin as an oil or oleoresin but urushiol is the more specific
term used to identify the oily toxin in the sap.
The urushiol-carrying sap is present in the roots, stems, leaves
and fruit (but not in the pollen). The roots, in particular, contain
high concentrations of urushiol. The sap is released when the plant
is damaged by bruising, cutting, mowing, scraping, wind, or insects.
One also can contact
urushiol indirectly after the sap gets on clothing, shoes, tools,
pets, and bark and firewood previously covered with poison ivy.
Urushiol is not volatile but shredding, mowing, or burning the plants
can create airborne particles that increases the chance of exposure.
The plant is most potent in
the spring and early summer when the sap is rising and the urushiol
content is high. The dreaded sap is less abundant in the winter but
still present and potent in the roots, stems, vines and twigs of the
plant. Therefore, if yard trimmings contain poison ivy (or poison oak
or sumac) residue, there
are urushiols about.
Urushiol is a stubborn substance. It has been shown to remain
potent on dead plants, clothing and contaminated objects for years
(bad news for everyone). In one study, plants stored in dry
conditions and in submerged water for 17 months were less potent but
stilled caused a rash in sensitive
individuals. However, these are not the biologically-rich conditions
of a compost pile. Because urushiol is organic, it is subject to
biological degradation (good news for composters). One reference
even suggests that under hot humid conditions, urushiol becomes inert
in about a week (more good
news for composters). Unfortunately, the research basis for this
statement is not identified.
Still, there are other indications that urushiol decomposes
naturally. First, we are not overrun with cases of poison ivy despite
the persistence of the toxin and ubiquity of the plants. Secondly,
according to Susan Carol Hauser, author of Natureís Revenge1, leaves
that naturally fall off the plant
do not contain urushiol. Furthermore, leaves do gradually lose
potency over time. Finally, there is anecdotal testimony. For
instance, commenting to the U.S. Composting Council Internet
listserv, the manager of a large yard trimmings facility mentioned
that users of raw shredded yard trimmings
mulch have reported developing the poison ivy rash while no users of
the composted product have.
Large-scale composting could be a rational approach for disposing
of poison ivy-laden yard trimmings, given the lack of good
alternatives and the fact that urushiol is thought to decompose under
conditions typical to composting. However, without more scientific
evidence, it remains a risky venture.
In any case, it deserves due caution and common sense in handling the
raw feedstocks and the products. To adequately decompose, the
urushiol must be exposed. Because poison oak, sumac, and even poison
ivy are woody plants with fairly thick stems, the plant material
needs to be shredded prior to
composting. However, shredding also releases the sap, spreading it
among the shredded material and possibly into the air near the
shredder. This raises concerns about using uncomposted mulch made
from the shredded yard trimmings containing poison ivy. As a side
note, given the uncertainties, it is
wise to keep poison ivy vegetation out of the backyard compost pile.
1 Additional sources of information: 1. Natureís Revenge, The Secrets
of Poison Ivy, Poison Oak, Poison Sumac and Their Remedies, Susan
Carol Hauser, Lyons & Buford Publishers; 2. Poison Ivy, Western
Poison Oak and Poison Sumac Agriculture and Agri-Food Canada website:
http://res.agr.ca/brd/poisivy.html; 3. Outsmarting Poison Ivy and Its
Cousins, by Isadora Stehlin, U.S. Food and Drug Administration
website: http://www.fda.gov/fdac/features/796_ivy.html; 4. Poison
Ivy, Oak & Sumac Information Center website : http://
poisonivy.aesir.com/.
On Apr 9, 2009, at 9:35 AM, Jack Hoeck wrote:
> Hello Compost World
>
>
>
> Does anyone have any info on the fate of poison oak/poison ivy oils in
> composting systems or in soil? Can it survive a 90 to 120 day compost
> cycle?
>
>
>
> Jack Hoeck
>
> VP Environmental Services
>
> Rexius
>
> 1275 Bailey Hill Rd.
>
> Eugene, OR 97402
>
> 1-541-342-1835
>
> 1-888-473-9487
>
> jackh at rexius.com
>
>
>
> Sustainable Solutions for Landscape, Community and the Environment
>
>
>
> <image001.jpg>_______________________________________
> Join us as the US Composting Council's 18th Annual Conference &
> Trade Show, January 24-27, 2010 at the Wyndham Orlando Resort, FL.
> The Largest Conference & Exhibition in North America for the
> Composting, Wood Waste, & Organics Recycling Industry. The Most
> Comprehensive Program of Training Courses, Educational & Technical
> Presentations, and Facility Tours & "Live" Equipment Demonstrations
> at the Disney/Reedy Creek Composting Facility. Conference
> Highlights & Program, Registration forms, Exhibitor Information and
> Sponsorship Opportunities available at the USCC website
> www.compostingcouncil.org or call the USCC at 631.737.4931
> ______________________________________________________________________
> _______
> Compost maillist - compost at mailman.cloudnet.com
> http://mailman.cloudnet.com/mailman/listinfo/compost
> _______________________________________
> This list is a service provided by the US Composting Council (USCC).
> (c) Copyright 2004 United States Composting Council - All rights
> reserved
>
> Opinions expressed do not necessarily represent the USCC, the
> Foundation, or the Board of Directors.
>
> Non-members of USCC are encouraged to join the Council through its
> website at: http://www.compostingcouncil.org/membership.cfm
>
> Members posting CC copies to the list and other addresses may have
> their posting privileges suspended. For discussion list policies
> and information regarding subscribing, unsubscribing, digest or
> other options, go to: http://mailman.cloudnet.com/mailman/listinfo/
> compost
>
> For additional help in unsubcribing or to report bugs and problems,
> send a message to the List Manager at
> compostlistmanager at compostingcouncil.org
More information about the Compost
mailing list