© 2013 by Pyrethroid Working Group. All rights reserved. On behalf of the Pyrethroid Working Group member companies: AMVAC, Bayer, Cheminova, DuPont, FMC, Syngenta, Valent Daniel M. Tessier Environmental Safety Assessment DuPont Crop Protection

Key questions regarding pyrethroids as wastewater microcontaminants  urban sources ?  influent concentrations ?  degradation / partitioning during wastewater processing ?  is known efate behavior (determined for agricultural settings) relevant in wastewater / POTWs ?  are current analytical methods sufficient?  effect of various wastewater treatment processes?  effluent concentrations?  PWG sought to answer these questions via laboratory, pilot and plant-scale studies as well as monitoring of selected California POTWs

Generalized POTW Processes

8 pyrethroids included in the studies Pyrethroidlog K ow Water Solubility (µg/L)Koc Bifenthrin ,000 Cyfluthrin ,000 Cypermethrin ,000 Deltamethrin ,000 Esfenvalerate ,000 Fenpropathrin ,500 -Cyhalothrin ,000 Permethrin ,000

Bench-scale treatability study Post-screen influent fortified at nominal 5  g/L (50  g/L permethrin)

anaerobic digester aerobic system

Results – Primary Settling Pyrethroid Calculated Primary Influent (µg/L) Measured Primary Influent (µg/L) Measured Primary Effluent (µg/L) Measured Sludge (µg/L) a Bifenthrin Fenpropathrin l-Cyhalothrin Permethrin Cyfluthrin Cypermethrin Esfenvalerate Deltamethrin a. Ca 0.85 gal / 200 gal influent ‡ No sorption to solids during primary settling

Pyrethroid Removal in Anaerobic Reactor

Pyrethroid Distribution in the Aerobic System

Conclusions: Bench-scale experiment  No sorption of pyrethroids to solids in primary settling (attributed to high DOC as alternate sorption compartment; short detention time)  Anaerobic digestion (biodegradation) ca. 32 – 79% removal of pyrethroid input.  Aerobic treatment - biodegradation + low sorption of pyrethroids to solids (13 – 51% remain in effluent)  >90% removal of effluent residual pyrethroids via ultra- filtration  Overall >90% removal in final filtered effluent

o Water & biosolids (sludge) phases collected over 1 week period & analyzed for pyrethroid concentrations o Data modeled via TOXCHEM+ (Hydromantis, Ontario, Canada) Plant-scale process modeling

Plant-scale process modeling: POTW schematic and sampling locations

TOXCHEM Representation of SRCSD POTW

Pyrethroid concentrations following aerobic treatment and ultrafiltration

Model Predicted vs Measured Concentrations

Modeling Results- Pyrethroid Fate NB: Measured concentrations of deltamethrin, fenpropathrin and esfenvalerate were too low for comparison against predicted concentrations

Conclusions: Full Scale Sampling / Process Modeling  Predicted concentrations in good agreement with measured values.  Log K ow used in the model (4.8 to 5.9) were generally lower than literature values (Laskowski, 2002) Attributable to high aqueous DOC.  Pyrethroid emissions to the atmosphere were predicted to be < 2.4% for all tested compounds  Median removal for biodegradation ranged from 44% to 65%  Median removal for sorption ranged from 30% to 42%  Pyrethroid discharge to effluent ranged from 2.9 to 11.9%

Pyrethroid Monitoring at California POTWs  PWG and Tri-TAC developed a partnership beginning in August 2007  Revised DPR requirement – July 15, 2011 Monitor for group III pyrethroids in influent, effluent, biosolids Monitor at least 20 POTWs in California o Submit analytical methods for influent, effluent and biosolids for eight pyrethroids

Study Design  32 California POTWs Varying size (volume of treated wastewater) Location (urban to rural) Treatment processes used (primary, secondary, tertiary) Customer base (residential, industrial, commercial) Population served  Facilities divided into 3 groups for sampling (north to south)  Samples Influent (31)-consecutive grabs Effluent (31)-consecutive grabs Biosolids (24)-grabs, composited in laboratory

 Samples analyzed for pyrethroids by two laboratories Group III pyrethroids (permethrin, cypermethrin, bifenthrin, cyfluthrin, esfenvalerate, l-cyhalothrin, deltamethrin, fenpropathrin)  TSS, TOC and TS determined by one laboratory  Extensive QA program (SWAMP comparable) Study Design (cont.)

Results: Influent - All Sites BifenthrinCyfluthrinCypermethrinPermethrin # of samples67 # of detects % detected Maximum74 ng/L MinimumND 30 Average15 ng/L11 ng/L35 ng/L330 ng/L Median9.7 ng/L7.4 ng/L21 ng/L230 ng/L # of detects = number of results that are above the limit of detection

Results: Biosolids - All Sites BifenthrinCyfluthrinCypermethrinPermethrin # of samples52 # of detects % detected Maximum1100 ng/g190 ng/g1000 ng/g11000 ng/g MinimumND Average150 ng/g34 ng/g110 ng/g1500 ng/g Median120 ng/g29 ng/g28 ng/g1200 ng/g # of detects = number of results that are above the limit of detection All results reported on a dry weight basis

Results: Effluent - All Sites BifenthrinCyfluthrinCypermethrinPermethrin # of samples62 # of detects % detected Maximum3.9 ng/L4 ng/L13 ng/L170 ng/L MinimumND Average0.89 ng/L0.60 ng/L2.11 ng/L20 ng/L Median0.6 ng/L0.3 ng/L1.3 ng/L9.4 ng/L # of detects = number of results that are above the limit of detection 3 sites contained no detectable residues of the 8 pyrethroid pesticides

Effect of Treatment Level on Effluent Concentration

Conclusions: POTW Monitoring  Pyrethroids are likely to be found in influents, effluents and biosolids from California POTWs  Effluent (31 sites) Pyrethroids were detected in 28 of the 31 sites examined Bifenthrin (82%) was the most frequently detected pyrethroid followed by cypermethrin (81%) and permethrin (65%) Total pyrethroid residues ranged from non-detectable to a maximum residue of 190 ng/L

Overall Conclusions  Pyrethroids are likely to be present in wastewater influent, effluent & biosolids.  Bench-scale and plant scale studies indicate ca. 90% removal of pyrethroids from influent streams via sorption & biodegradation; this benchmark is reflected in real-world monitoring.  POTW process parameters (e.g detention time, 1 o vs 2 o vs 3 o treatment) anticipated to influence % removal; effective modeling procedures are available to predict pyrethroid fate in POTW matrices.  Baseline data and assumptions from e-fate studies must be applied judiciously to POTW investigations (e.g, Kow; Koc).

Key Personnel  PWG /DuPont Crop Protection Al Barefoot Dan Tessier  HDR Engineering Joe Cleary Joy McGrath  Sacramento Regional Sanitation District Heather Ramil Kurt Ohlinger  ABC / Morse Laboratories Kevin Clark  Coalition for Urban/Rural Environmental Stewardship Jim Markle  Van Buuren Consulting, LLC Beverly van Buuren  Hydromantis Hugh Monteith