# USEPA/OPP

- U.S. Composting Council Meeting

-- Persistent Herbicides in Compost

, July 16, 2015

USEPA/Office of Pesticide Programs (OPP) Attendees :

Pesticide Re

- evaluation Division: Tracy Perry, Veronica Dutch, Kelly Sherman

Registration Division: Kay Montague, Reuben Baris

Ecological Fate and Effects Division: William Eckel

Health Effects Division: Christina Swartz, Doug Dotson

U.S. Composting Council (USCC) Attendees & Partners :

Cary Oshins

- USCC

Craig Coker , PE , Coker Composting & Consulting

Dr. Fred Michel, Ohio State University

Meeting Summary

• The USCC requested an update on the registration review status of certain herbicides (i.e.,

aminopyralid, clopyralid, picloram) that may persist through the composting process and cause

damage to non

- targ et plants receiving the composted material. OPP explained that it is preparing to

formally require

, through the A gency’s Data Call

- In process, the data needs that are outlined in the

final work plan for these pesticides. Several special studies will be required t hat are expected to

inform the Agency’s understanding of how persistent these herbicides are in compost and manure

(i.e., dissipation in compost and associated environmental chemistry methods)

. OPP requested

USCC assistance in identifying repres entative composts to be used in the spe cial studies.

• The USCC also emphasized their interest in access to inexpensive methods to detect the presence of

persistent herbicides in feedstocks received for composting.

• OPP noted that new herbicides of similar c hemistry to these three pyridine herbicides are being

screened for potential compost issues before their registrations are granted and that the risk

assessments for these new herbicides would be available in the public docket.

• Given the movement to ban dis posal of food wastes in landfills and redirect them to composting

facilities

, the USCC expressed concern regarding potential residues of persistent herbicides in food

waste

. OPP noted that actual levels of pesticides in/ on foods are often orders of magnit ude lower

than tolerances, which are the maximum lega l levels for enforcement purposes

. R esidues of

persistent herbicides in food waste are not expected to be a significant source of exposure in

compost.

• Dr . Michel presented his recent national survey of commercial composting facilities, in which three

out of 70 composts tested exhibited herbicide phy totoxicity symptoms. There was no correlation of

phytotoxicity with location, feedstock, or composting method.

• USCC has set u p a confidential incident reporting system for composting facilities and has received

three phytotoxicity reports this year.

• OPP noted that the meeting summary and a copy of Dr. Michel’s presentation would be added to the

registration review dockets for pi cloram (EPA

- HQ

- OPP

- 2013

- 0740), aminopyralid (EPA

- HQ

- OPP

2013

- 0749 ), and clopyralid (EPA

- HQ

- OPP

- 2014

- 0167).HowWidespreadarePersistentHerbicides?ResultsofaNationwideCompostSurveyFrederickC.MichelJr.*,KatherineM.Speicher,BingZang,LuisHuezoDepartmentofFood,AgriculturalandBiologicalEngineeringTheOhioStateUniversity,1680MadisonAvenue,Wooster,OHUSA44691.*michel.36@osu.eduPersistentHerbicidesClopyralid,Aminopyralid,Aminocyclopyrachlor,PicloramActiveingredientsinover30herbicidesHighlyeffectiveatlowdosageswithverylowhuman,animalandaquaticenvironmentrisk.Controlannualandperennialweedsincropproductionandturfaswellasinvasiveweedsinnaturalareasandpasture.EffectiveagainstCreepingThistle,CreepingCharlieandothernoxious,andinvasivedifficulttocontrolperennialbroadleafweeds.Persistenceandpotencymeansfewerapplications.Feedstockssuchasturf,manure,foodwaste,deadtreesandhaymaycancontainresidualamountsoftheseherbicides.Aminocyclopyrachlor6‐amino‐5‐chloro‐2‐Cyclopropyl pyrimidine‐4‐carboxylicacidClopyralid3,6‐dichloro2‐PyridinecarboxylicacidAminopyralid3,6‐dichloro‐2‐Pyridinecarboxylicacid1‐aminoNPyridine/PyrimidineCarboxylicAcidHerbicides4‐Amino‐3,5,6‐trichloro‐2‐PyridinecarboxylicacidPicloramPyrimidine/PyridineCarboxylicAcidHerbicidesActiveIngredientName ManufacturerFirstRegistered TradeNamesObservable ImpactLevelinCompost(ppb)PicloramDowAgroSciences1963Tordon,Grazon,Access,Pathway5ClopyralidDowAgroSciences1978Curtail,RedeemR&P,Transline,Confront,Lontrel10AminopyralidDowAgroSciences2005Milestone,Forefront,Chaparral1Aminocyclopyrachlor DuPont 2010Imprelis,Perspective,Viewpoint,Streamline2Soiltestinglabscannotreliablymeasuretheconcentrationsofthesechemicalsincompostsatlevelsbelow10ppbAminopyralidinYTCompost(ppbdb)01050100Concentrationvaluesaretheoverallconcentrationsinthemedia.DairyManureCompostControl50%CompostNodetectableHerbicidesinCompost52weekoldcompost50%CompostHerbicidesdetected=6ppbaminopyralid,7ppbclopyralidAllowableherbicideconcentrationsinfoodsTreatments (Values are mg/kg)SampledayUntreatedGranular Herbicide Liquid HerbicideClopyralidwet wet dry ash wet dry ash wet dry ashDay 0 NT 1.5±0.3 5.2±1.0 37.5 ±8.1 3.8±0.4 13.4±1.2 85.2 ±15.1 34±4 112±14 661 ±54Day 1 0 NT 2.0±0.4 6.9±1.5 37.8 ±7.7 4.7±0.9 17.1±2.5 82.9 ±19.0 44±5 142±20 637 ±60Day 30 NT 2.9±0.5 6.9±1.6 34.6 ±8.0 6.5±1.4 16.7±2.2 73.8 ±17.8 47±1 99±2 413 ±13Day 50 NT 3.0±0.5 6.5±1.6 31.2 ±7.8 6.7±1.4 17.2±2.9 69.7 ±18.5 53±4 104±12 403 ±51Day 78 <0.01 3.5±0.5 6.3±1.5 28.9 ±6.2 6.6±1.6 16.1±2.0 62.8 ±14.3 49±4 81±16 305 ±56Day 100 <0.01 2.8±0.5 6.5±1.6 28.7 ±7.5 6.6±1.2 15.3±2.1 59.4 ±13.8 50±4 109±15 395 ±34Day 178 NT 2.5±0.7 4.8±1.6 20.0 ±6.2 6.9±1.2 10.7±2.2 37.0 ±12.1 31±2 57±3 194 ±16% Loss +67% -8% -47% +82% -20% -57% -9% -49% -71%DifferenceConcentrations of PH Herbicides during CompostingCompostAgeConcentrationsofPersistentherbicidesinCompostsofdifferentagesatanimpactedfacilityWeeks•Compostsamples(2kg)requestedfromallUSCCmembers–Compostwastobe,“justreadyforsaleoruse”.•Facilityinformationalsorequested–Location–Compostage–Feedstock(s)used–Compostingsystem(s)employed•Windrow,AeratedStaticPile,Invessel,etc.–WhethertherehavebeencomplaintsaboutcompostdamagingplantsSurveyofUSCompostingFacilitiesSourcesofsurveycompostsFeedstocks31%38%AgesofsurveycompostsMean=8.1± 8.2monthsCompostAge(months)51%are6monthsoldorlessHerbicideBioassay•Plantgrowthmedia–50%Compost–50%Peatbasedpottingmix•Moistureadjustedto80%saturation•Sownwithfourgardenbeanseeds,culledtoone–Verysensitivetopyridineandpyrimidinecarboxylicacidherbicides•Incubatedingreenhouseat>60F•ArtificiallightinginWinter,12hperday•Plantswatereddailytooriginalweight–Deionizedordistilledwaterused–Nodrainagetopreventherbicidewashout•Planthealthassessedafter35‐50days–Leafshape,Leafnumber,height,dryweightResultsofPhytotoxicityTesting•70compoststested–4showedleafcurling•NewEngland,Midwest,Southeast,Northwest–3exhibitedlossofapicaldominance•NewEngland,Midwest,Southeast–3sitesreportedherbicideproblems•NewEngland,Midwest,Northwest–13sitesreceivedhorsemanure/beddingfeedstockLeafcurlingandmalformation(Positivecontrol)LossofapicalDominance(testedsample)Nosymptoms(testedsample)HerbicideConcentrationsinTestCompostsandControlsSampleECAminopyralidPicloramClopyralidLossofApicalDom.LeafCurlingFeedStocks#(DS/m) (ppb) (ppb) (ppb) (Y/N) (Y/N)CompostA 1.65 0.1 3.3 2.2 N N L,G,HMCompostB 7.27 2.3 3.6 6.6 Y/Y Y/Y HMCompostC 1.28 1.7 18.1 2.4 Y Y HM,WC,H,SDCompostD+1ppbAP1.809.286.5 3.3 N* N*L,G,FW,WC,CCCompostONegativecontrol‐0 0.5 0.9 N NDM,PM,WC,LCompostMPositiveControl1.73 0.6 2.1 0.3 Y/N Y/N FW,HM,L• Chemicaltestingtodeterminetheconcentrationsofherbicidesinpositivesamples.• Reliableplantbioassaystoscreencompostsandfeedstocksforherbicidecontamination.• Development,validationandpublicationofchemicaltestmethodsforthemeasurementofherbicidesincompostsatppb.• Determinationofthefateandpersistenceofrecalcitrantherbicidesduringcompostingandinsoil.• Researchonlowcostmethodstoremediatecontaminatedcomposts– Inoculantsthatareenrichedwithmicroorganismsabletodegraderecalcitrantherbicides– AdsorbentsforherbicidesincompostsResearchNeedsQuestions?GrowthVariationinComposts•Underthesamegrowthconditionsplantgrowthresponsedifferedindifferentcomposts•PlantsgrownduringdifferentseasonsalsohaddifferentresponsesHerbicidePhytotoxicitySymptomsRemediationofHerbicideToxicity•Fiveadditivestested–ActivatedCarbon,Zeolite,WoodAsh,Biochar,Osorb•Addedto2%onadryweightbasis•Compostaddedat20%•Aminopyralidaddedat0,3,32,128and639ppb•Plantgrowthassessed–Leafcurling,germination,lossofapicaldominanceActivatedCarbon(2%)AminopyralidConcentration(ppb=ng/gcompostdw)639ppb128ppb32ppb3ppb0ppbNoGerminationOsorb (2%)AminopyralidConcentration(ppb=ng/gcompostdw)639ppb128ppb32ppb3ppb0ppbZeolite(2%)AminopyralidConcentration(ppb=ng/gcompostdw)639ppb128ppb32ppb3ppb0ppbWoodAsh(2%)AminopyralidConcentration(ppb=ng/gcompostdw)639ppb128ppb32ppb3ppb0ppbPhytoxicityScale(0‐4)DeadLADNoneppbAminopyralidConclusions• PropertiesofcompostfromaroundtheUSvary– EC1to11dS/m,pH5.6to8.8• Plantgrowthresponseincompostmediawasalsovariable– Time,season,temperature• 3of70compostsexhibitedherbicidephytotoxicity• Nocorrelationwithlocation,feedstockormethod• Woodashandactivatedcarbonat2%remediatedcontaminatedcompostswith30to600ppbaminopyralid