# Department of Pesticide Regulation

Mary-Ann Warmerdam

Director 

# M E M O R A N D U M Arnold Schwarzenegger

Governor



# 1001 I Street • P.O. Box 4015 • Sacramento, California 95812-4015 • www.cdpr.ca.gov

A Department of the California Environmental Protection Agency

Printed on recycled paper, 100% post-consumer--processed chlorine-free. 

# TO: John S. Sanders, Ph.D.

Environmental Program Manager II

Environmental Monitoring Branch

FROM: Mark Pepple

Staff Environmental Scientist

Environmental Monitoring Branch

916-324-4086

DATE: May 29, 2009

SUBJECT: PROCEDURE FOR IDENTIFYING PESTICIDES WITH A HIGH POTENTIAL

TO CONTAMINATE SURFACE WATER

This memorandum explains how the pesticides th at may be regulated to prevent surface water

contamination were identified.

Environmental Monitoring staff are developi ng regulations to prot ect surface water from

pesticides. The regulations will list pesticides th at have a high potential to contaminate surface

water and then specify mitigation measures designed to protect beneficial uses of waters of the

state from those pesticides.

We identified pesticides that have a high potential to contaminated surface water by first listing

all pesticides detected in surface water or sediment from the Department of Pesticide

Regulation’s (DPR’s) Surface Water Database at

< http://www.cdpr.ca.gov/docs/emon/surfwtr/surfcont.htm >. The database contains sampling

results from 1991 to the present. To that list we added fipronil and pyrethrins, which are draft

detections pending completion of the monitoring re ports (Table 1). For screening purposes, we

also added all active ingredient is omers of pesticides detected, and the associated salts, esters,

and/or amines of 2,4-D, dicamba, glyphosate, and MCPA (Table 2)

.

The following five pesticides we re removed from the list because they had single detections

(number of samples analyzed in parentheses) : bromoxynil octanoate (193), fenamiphos (635),

hydramethylnon (203), paraquat dichloride (312), and tetrachlorvinphos (1243). Five additional

pesticides were removed from the list for the stated reasons: endosulfa n because it is already

subject to California-only label re quirements to protect surface water; molinate because its use

will no longer be allowed after August 2009; pyrethrins because they have very short half-lives;

terbuthylazine because all of its uses would qualify for the prov ision that would exempt all

intentional applications to water in accordance with all regulatory requirements; and thiobencarb

because it is being addressed by the rice industry and the Central Valley Regional Water Quality

Control Board in a different forum to protect surface water.

# John S. Sanders, Ph.D.

May 29, 2009

Page 2

Finally, the list was screened to exclude pesticides that are detected in surf ace water at levels that

are relatively low compared to the levels that cau se aquatic toxicity or that are protective of

human health in drinking water. This screeni ng process was not used to remove any pesticides

remaining on the list that were detected excl usively in sediment. The U.S. Environmental

Protection Agency (EPA) Aquatic Life Benchmark Table, as of November 2008,

http://www.epa.gov/oppefed1/ecoris k_ders/aquatic_life_benchmark.htm > was used to obtain the

lowest aquatic life benchmark for pesticides on the DPR draft list. It should be noted that EPA is

in the process of revising the a quatic life benchmarks so values in Table 2, as of November 2008,

may be different from those in the current EPA Aquatic Life Benchmark Table. For pesticides

with no aquatic life benchmark, the U.S. EPA Offi ce of Pesticide Programs Pesticide Ecotoxicity

Database < http://www.ipmcenters .org/Ecotox/index.cfm >, as of November 2008, was used to

obtain the lowest acute LC50 or EC 50, or the lowest chronic no observable effect level (NOEL)

for the standard test species that U.S. EPA uses to assess pesticide aqua tic toxicity. For acute

toxicity to freshwater fish, the standard test spec ies is usually rainbow trout or bluegill sunfish;

for chronic toxicity to freshwater fish, rainbow trout or fathead minnow; for acute and chronic

toxicity to freshwater invertebrates, midge, scud (amphipods), or daphnids; for acute toxicity to

freshwater nonvascular plants, gr een algae or diatoms; and for acute toxicity to freshwater

vascular plants, duckweed. To be consistent w ith the methodology used to establish aquatic life

benchmarks, the lowest toxicity values were multiplied by the appropriate levels of concern

(LOC) factors (LOC=1 for chronic fish and inve rtebrate values, and for acute vascular and

nonvascular plant values; LOC=0.5 for acute fish and invertebrate values).

In addition, the Department of Fish and Game ha s completed hazard assessments for 17 of the 71

pesticides detected in surface water and revi ewed by DPR for their potential to contaminate

surface water. The lowest values to protect human health or aquatic organisms used in the DPR

screening in Table 2 were compared with the lowest values to protect aquatic organisms

developed in the DFG hazard assessments. On ly toxicity values measured on the active

ingredient were used unless there were only da ta for formulated products. We computed the

ratio of the lowest DFG value to the lowest DPR value. Ratios of less than one indicate that

DPR values were less protective of aquatic orga nisms than the DFG values. The ratios ranged

from 0.03 for cypermethrin to 173,000 for 2,4-D. The median ratio was 6.2. Although the DFG

values were lower for carbofuran, chlorpyr ifos, cypermethrin, S-cypermethrin, diazinon,

methidathion, methomyl, and methyl parathion, they did not result in any change in the list of

pesticides identified as having a high poten tial to contaminate surface water.

For drinking water health protective levels, th e California Central Valley Regional Water Quality

Control Board’s Compilation of Water Quality Goals at

< http://www.swrcb.ca.gov/rwqcb5/water_issues/w ater_quality_standards_limits/water_quality_g

oals/wq_goals_2008.pdf >, as of November 2008, were used to identify, for each pesticide, either

a California Department of Public Health (C DPH) or U.S. EPA maximum contaminant level

(MCL), or, if an MCL is not established, the lowest drinking water concentration level for

# John S. Sanders, Ph.D.

May 29, 2009

Page 3

protection of human health of one of the fo llowing levels: a U.S. EPA Integrated Risk

Information System reference dose as a drinking water level, a drinking water health advisory

(HA) or suggested no-adverse-res ponse level for toxicity other than cancer risk, or various

measures of one-in-a-million incremental cancer risk estimates for drinking water, as footnoted

in the table below.

If the lowest of the aquatic life benchmark or acu te or chronic aquatic toxicity value, or human

health protection level, was 50 pa rts per billion (ppb) or above (fiv e times or greater than the ten

ppb 95th percentile of detected water concentrations in the DPR’s Surface Water Database), the

pesticide was excluded from the draft DPR list. The following pesticides were excluded because

their aquatic toxicity or level to protect human health is 50 ppb or higher: 2,4-D and related

pesticides, butylate, chlorthal dimethyl, cy cloate, EPTC, glyphosate and related compounds,

metalaxyl, napropamide, oxamyl, prometon, propi conazole, tebuthiuron, tr iclopyr butoxy ethyl

ester, and triclopyr triethylamine salt.

# John S. Sanders, Ph.D.

May 29, 2009

Page 4

A summary of these data for the pesticides sc reened for determining potential to contaminate

surface water is shown in Table 2.

Table 1. Pesticides detected in surface water or sediment

chemical DPR chem code

2,4-D 636

alachlor 678

aldicarb 575

atrazine 45

azinphos-methyl 314

benefin 53

bentazon, sodium salt 1944

bifenthrin 2300

bromacil 83

bromoxynil octanoate 834

butylate 565

carbaryl 105

carbofuran 106

chlorpyrifos 253

chlorthal-dimethyl 179 synonym: dacthal and DCPA

cycloate 516

cyfluthrin 2223

cypermethrin 2171

DDVP 187 synonym: dichlorvos

deltamethrin 3010

diazinon 198

dicamba 200

dicofol 346

dimethoate 216

disulfoton 230

diuron 231

endosulfan 259

EPTC 264 synonym: eptam

esfenvalerate 2321

ethalfluralin 2166

ethoprop 404

fenamiphos 1857

fenoxycarb 2283

# John S. Sanders, Ph.D.

May 29, 2009

Page 5

chemical DPR chem code

fenpropathrin Initially omitted

fipronil 3995

glyphosate 2997

hexazinone 1871

hydramethylnon 2203

imidacloprid 3849

lambda cyhalothrin 2297

linuron 361

malathion 367

MCPA 2326

MCPA, dimethylamine salt 786

metalaxyl 2132

methidathion 1689

methiocarb 375

methomyl 383

methyl isothiocyanate 392

methyl parathion 394

metolachlor 1996

metribuzin 1692

molinate 449

napropamide 1728

norflurazon 2019

oryzalin 1868

oxadiazon 2017

oxamyl 1910

oxyfluorfen 1973

paraquat dichloride 1601

pendimethalin 1929

permethrin 2008

phorate 478

phosmet 335

prodiamine 2236

prometon 499

prometryn 502

propanil 503

propargite 445

propiconazole 2276

propoxur 62

# John S. Sanders, Ph.D.

May 29, 2009

Page 6

chemical DPR chem code

propyzamide 694

pyrethrins 510

pyriproxyfen 4019

S.S.S-tributyl phosphorotrithioate 190 synonym: tribufos

siduron 603

simazine 531

tebuthiuron 1810

terbuthylazine 3004

tetrachlorvinphos 305

thiobencarb 1933

triallate 49

triclopyr 2131

trifluralin 597John S. Sanders, Ph.D.May 29, 2009Page 7Table 2. Pesticides detected in surface water (and related chemicals) screened for possible regulation to protect surface waterCommon nameMCL orLowestDrinkingWaterConcentration forProtectionof HumanHealth(ppb)Lowest U.S. EPAAquatic Acute orChronic Benchmark(A), or Lowest OPPDatabase Value(B) Multiplied byLevel of Concern2(LOC) Factor (ppb)Test type (A) or Species/testtype (B)Lowest AquaticToxicity Value orHuman HealthProtective Level forDrinking WaterReason forexclusion fromdraft list forsurface waterregulation2,4-D and relatedpesticides70a1.124B x 0.5 = 0.56Daphnia magnaAcute invertebrates0.56Alachlor 2a1.64A Acute nonvascular plants 1.64Aldicarb 3b0.46A Chronic fish 0.46Atrazine 1c1A Acute nonvascular plants 1Azinphosmethyl 87.5d.036A Chronic invertebrates .036Benefin(benfluralin)700d1.9A Chronic fish 1.9John S. Sanders, Ph.D.May 29, 2009Page 8Common nameMCL orLowestDrinkingWaterConcentration forProtectionof HumanHealth(ppb)Lowest U.S. EPAAquatic Acute orChronic Benchmark(A), or Lowest OPPDatabase Value(B) Multiplied byLevel of Concern2(LOC) Factor (ppb)Test type (A) or Species/testtype (B)Lowest AquaticToxicity Value orHuman HealthProtective Level forDrinking WaterReason forexclusion fromdraft list forsurface waterregulationBentazon, sodiumsalt18c4500A Acute nonvascular plants 18beta-Cyfluthrin NA.007B (CyfluthrinNOEL) x 1 = .007Daphnia magna/ Chronicinvertebrates0.007Bifenthrin 110e0.0013B (NOEL) x 1= .0013Daphnia magna/ Chronicinvertebrates0.0013Bromacil 70f6.8ASelenastrum capricornutum/Acute nonvascular plantsAcute nonvascular plants6.8Bromoxyniloctanoate1140e2.5A (bromoxynil) Chronic invertebrates 2.5 Single detectionButylate 350e105A Acute fish 105Lowest value50 ppb or moreJohn S. Sanders, Ph.D.May 29, 2009Page 9Common nameMCL orLowestDrinkingWaterConcentration forProtectionof HumanHealth(ppb)Lowest U.S. EPAAquatic Acute orChronic Benchmark(A), or Lowest OPPDatabase Value(B) Multiplied byLevel of Concern2(LOC) Factor (ppb)Test type (A) or Species/testtype (B)Lowest AquaticToxicity Value orHuman HealthProtective Level forDrinking WaterReason forexclusion fromdraft list forsurface waterregulationCarbaryl 40g0.5A Chronic invertebrate 0.5Carbofuran 18c0.75A Chronic invertebrate 0.75Chlorpyrifos 2f.04A Chronic invertebrate 0.04Chlorthal dimethyl 70e11000AAcute vascular andnonvascular plants70Lowest value50 ppb or moreCycloate NA 1300A Acute invertebrates 1300Lowest value50 ppb or moreCyfluthrin NA0.004B (NOEL) x 1 =.004Daphnia magna/ Chronicinvertebrates0.004John S. Sanders, Ph.D.May 29, 2009Page 10Common nameMCL orLowestDrinkingWaterConcentration forProtectionof HumanHealth(ppb)Lowest U.S. EPAAquatic Acute orChronic Benchmark(A), or Lowest OPPDatabase Value(B) Multiplied byLevel of Concern2(LOC) Factor (ppb)Test type (A) or Species/testtype (B)Lowest AquaticToxicity Value orHuman HealthProtective Level forDrinking WaterReason forexclusion fromdraft list forsurface waterregulationCypermthrin, ciscypermethrin70e.069AChronic invertebrates.069S-cypermethrin 70feAssume same ascypermethrinAssume same as cypermethrin 0.69DDVP (Assumebreakdownproduct of naledlisted below)Deltamethrin NA.003B (EC50) x 0.5 =.0015Daphnia magna/ Acuteinvertebrates0.0015Diazinon 1gf0.105A Acute invertebrates 0.105Dicamba,dimethylamine salt8.75d61A (Based onlowest toxicity valuesof dicamba)Acute nonvascular plants 8.75John S. Sanders, Ph.D.May 29, 2009Page 11Common nameMCL orLowestDrinkingWaterConcentration forProtectionof HumanHealth(ppb)Lowest U.S. EPAAquatic Acute orChronic Benchmark(A), or Lowest OPPDatabase Value(B) Multiplied byLevel of Concern2(LOC) Factor (ppb)Test type (A) or Species/testtype (B)Lowest AquaticToxicity Value orHuman HealthProtective Level forDrinking WaterReason forexclusion fromdraft list forsurface waterregulationDicamba, sodiumsalt8.75d61A (Based onlowest toxicity valuesof dicamba)Acute nonvascular plants 8.75Dicofol NA80B (EC50) x 0.5 =40Daphnia magna/Acuteinvertebrate40Dimethoate 1.4fe0.5A Chronic invertebrates 0.5Disulfoton .3e.01A Chronic invertebrates .01Diuron 2g2.4A Acute nonvascular plants 2John S. Sanders, Ph.D.May 29, 2009Page 12Common nameMCL orLowestDrinkingWaterConcentration forProtectionof HumanHealth(ppb)Lowest U.S. EPAAquatic Acute orChronic Benchmark(A), or Lowest OPPDatabase Value(B) Multiplied byLevel of Concern2(LOC) Factor (ppb)Test type (A) or Species/testtype (B)Lowest AquaticToxicity Value orHuman HealthProtective Level forDrinking WaterReason forexclusion fromdraft list forsurface waterregulationEndosulfan 42e.07A Chronic invertebrates .07Already subjectto Californiaonly labelrequirements toprotect surfacewaterEPTC NA 810A Chronic invertebrates 810Lowest value50 ppb or moreEsfenvalerate NA.017AChronic invertebrates .017Ethalfluralin NA 0.4A Chronic fish 0.4Ethoprop NA 22A Acute invertebrates 22John S. Sanders, Ph.D.May 29, 2009Page 13Common nameMCL orLowestDrinkingWaterConcentration forProtectionof HumanHealth(ppb)Lowest U.S. EPAAquatic Acute orChronic Benchmark(A), or Lowest OPPDatabase Value(B) Multiplied byLevel of Concern2(LOC) Factor (ppb)Test type (A) or Species/testtype (B)Lowest AquaticToxicity Value orHuman HealthProtective Level forDrinking WaterReason forexclusion fromdraft list forsurface waterregulationFenamiphos1.7f.12B (NOEL) x 1 =.12Daphnia magna/ Chronicinvertebrates0.12 Single detectionFenoxycarb NA.0016B (NOEL) x 1 =.0016Daphnia magna/ Chronicinvertebrates0.0016Fenpropathrin NA.013B (NOEL) x 1 =.013Pimephales promelas/Chronic fish0.013Fipronil NA6.6B (NOEL) x 1 =6.6Oncorhynchus mykiss/Chronic fish6.6gammaCyhalothrin35e0.00042B (LC50) x.5 = .00021Gammarus pseudolimnaeus/Acute invertebrates0.00021Glyphosate 700a1800A Chronic fish 700Lowest value50 ppb or moreJohn S. Sanders, Ph.D.May 29, 2009Page 14Common nameMCL orLowestDrinkingWaterConcentration forProtectionof HumanHealth(ppb)Lowest U.S. EPAAquatic Acute orChronic Benchmark(A), or Lowest OPPDatabase Value(B) Multiplied byLevel of Concern2(LOC) Factor (ppb)Test type (A) or Species/testtype (B)Lowest AquaticToxicity Value orHuman HealthProtective Level forDrinking WaterReason forexclusion fromdraft list forsurface waterregulationGlyphosate,diammonium saltAssumesame asglyphosateAssume same asglyphosateAssume same as glyphosateAssume same asglyphosateLowest value50 ppb or moreGlyphosate,isopropylaminesaltAssumesame asglyphosate42450A Acute fishAssume same asglyphosateLowest value50 ppb or moreGlyphosate,monoammoniumsaltAssumesame asglyphosateAssume same asglyphosateAssume same as glyphosateAssume same asglyphosateLowest value50 ppb or moreGlyphosate,potassium saltAssumesame asglyphosateAssume same asglyphosateAssume same as glyphosateAssume same asglyphosateLowest value50 ppb or moreHexazinone 230e7A Acute nonvascular plants 7Hydramethylnon1NA 5B (EC50) x 1 = 5Chlorella sp./ Acutenonvascular plants5 Single detectionJohn S. Sanders, Ph.D.May 29, 2009Page 15Common nameMCL orLowestDrinkingWaterConcentration forProtectionof HumanHealth(ppb)Lowest U.S. EPAAquatic Acute orChronic Benchmark(A), or Lowest OPPDatabase Value(B) Multiplied byLevel of Concern2(LOC) Factor (ppb)Test type (A) or Species/testtype (B)Lowest AquaticToxicity Value orHuman HealthProtective Level forDrinking WaterReason forexclusion fromdraft list forsurface waterregulationImidacloprid NA 1.05A Chronic invertebrates 1.05lambdaCyhalothrin35e.0019B (NOEL) x 1 =.0019Daphnia magna/ Chronicinvertebrates0.0019Linuron 1.4e0.09A Chronic invertebrates 0.09Malathion 100f.000026A Chronic invertebrates .000026MCPA 3.5e170A Acute vascular plants 3.5MCPA,dimethylamine salt130A Acute vascular plantsAssume same asMCPAJohn S. Sanders, Ph.D.May 29, 2009Page 16Common nameMCL orLowestDrinkingWaterConcentration forProtectionof HumanHealth(ppb)Lowest U.S. EPAAquatic Acute orChronic Benchmark(A), or Lowest OPPDatabase Value(B) Multiplied byLevel of Concern2(LOC) Factor (ppb)Test type (A) or Species/testtype (B)Lowest AquaticToxicity Value orHuman HealthProtective Level forDrinking WaterReason forexclusion fromdraft list forsurface waterregulationMCPA, 2-ethylhexyl esterAssumesame asMCPA20A Acute vascular plantsAssume same asMCPAMCPA, isooctylesterAssumesame asMCPA20A (Assume sameas MCPA, 2-ethylhexyl ester)Assume same as MCPA, 2-ethyl hexyl esterAssume same asMCPAMetalaxyl 420e1200B (NOEL) x 1 =1200Daphnia magna/ Chronicinvertebrates420Lowest value50 ppb or moreMethidathion 0.7e0.66A Chronic invertebrates 0.66Methiocarb NA 0.1A Chronic invertebrates 0.1Methomyl 175d0.7A Chronic invertebrates 0.7John S. Sanders, Ph.D.May 29, 2009Page 17Common nameMCL orLowestDrinkingWaterConcentration forProtectionof HumanHealth(ppb)Lowest U.S. EPAAquatic Acute orChronic Benchmark(A), or Lowest OPPDatabase Value(B) Multiplied byLevel of Concern2(LOC) Factor (ppb)Test type (A) or Species/testtype (B)Lowest AquaticToxicity Value orHuman HealthProtective Level forDrinking WaterReason forexclusion fromdraft list forsurface waterregulationMethylisothiocyanate(Assume source isdazomet, metampotassium ormetam sodium)50h25.6A (metamsodium)Acute fish 25.6 Single detectionMethyl parathion 1f0.25A Chronic invertebrates 0.25Metolachlor 70f1A Chronic invertebrates 1S-metolachlor70f(metolachlor)1A (metolachlor) Chronic fish 1Metribuzin 70f1.29A Chronic invertebrates 1.29John S. Sanders, Ph.D.May 29, 2009Page 18Common nameMCL orLowestDrinkingWaterConcentration forProtectionof HumanHealth(ppb)Lowest U.S. EPAAquatic Acute orChronic Benchmark(A), or Lowest OPPDatabase Value(B) Multiplied byLevel of Concern2(LOC) Factor (ppb)Test type (A) or Species/testtype (B)Lowest AquaticToxicity Value orHuman HealthProtective Level forDrinking WaterReason forexclusion fromdraft list forsurface waterregulationMolinate 20c105A Acute Fish 20The use ofmolinate will beterminated as of8/31/2009Naled (assumesource of detectedDDVP)14e0.0058A Chronic invertebrates 0.0058Napropamide 700e1100AChronic fish and chronicinvertebrates700Lowest value50 ppb or moreNorflurazon 280e9.7A Acute nonvascular plants 9.7Oryzalin 35e42A Acute nonvascular plants 35Oxadiazon 35e0.88B (NOEL) x 1 =.88Oncorhynchus mykiss/Chronic fish0.88John S. Sanders, Ph.D.May 29, 2009Page 19Common nameMCL orLowestDrinkingWaterConcentration forProtectionof HumanHealth(ppb)Lowest U.S. EPAAquatic Acute orChronic Benchmark(A), or Lowest OPPDatabase Value(B) Multiplied byLevel of Concern2(LOC) Factor (ppb)Test type (A) or Species/testtype (B)Lowest AquaticToxicity Value orHuman HealthProtective Level forDrinking WaterReason forexclusion fromdraft list forsurface waterregulationOxamyl 50c90A Acute invertebrates 50Lowest value50 ppb or moreOxyfluorfen 20e0.29A Acute nonvascular plants 0.29Paraquatdichloride13.2e.55B (EC50) x 1 =.55Navicula pelliculosa/ Acutenonvascular plant0.55 Single detectionPendimethalin 280e5.4A Acute nonvascular plants 5.4Permethrin 350e0.0014A Chronic invertebrates 0.0014Phorate .7d0.21A Chronic invertebrates 0.21John S. Sanders, Ph.D.May 29, 2009Page 20Common nameMCL orLowestDrinkingWaterConcentration forProtectionof HumanHealth(ppb)Lowest U.S. EPAAquatic Acute orChronic Benchmark(A), or Lowest OPPDatabase Value(B) Multiplied byLevel of Concern2(LOC) Factor (ppb)Test type (A) or Species/testtype (B)Lowest AquaticToxicity Value orHuman HealthProtective Level forDrinking WaterReason forexclusion fromdraft list forsurface waterregulationPhosmet 140e0.8A Chronic invertebrates 0.8Prodiamine NA1.5B (NOEL) x 1 =1.5Daphnia magna/ Chronicinvertebrates1.5Prometon 100f98AAcute nonvascular plants 98Lowest value50 ppb or morePrometryn 28e1A Acute nonvascular plants 1Propanil 35e9.1A Chronic fish 9.1Propargite 140e9A Chronic invertebrates 9John S. Sanders, Ph.D.May 29, 2009Page 21Common nameMCL orLowestDrinkingWaterConcentration forProtectionof HumanHealth(ppb)Lowest U.S. EPAAquatic Acute orChronic Benchmark(A), or Lowest OPPDatabase Value(B) Multiplied byLevel of Concern2(LOC) Factor (ppb)Test type (A) or Species/testtype (B)Lowest AquaticToxicity Value orHuman HealthProtective Level forDrinking WaterReason forexclusion fromdraft list forsurface waterregulationPropiconazole 91e93A Acute nonvascular 91Lowest value50 ppb or morePropoxur NA 5.5A Acute invertebrates 5.5Propyzamide(pronamide)2g600A Chronic invertebrate 2Pyriproxyfen NA.01B (NOEL) x 1 =.01Daphnia magna/ Chronicinvertebrates0.01Siduron NA.13B (LC50) x .5= .065Lepomis macrochirus/ Acutefish0.065Simazine 4a36A Acute nonvascular 4John S. Sanders, Ph.D.May 29, 2009Page 22Common nameMCL orLowestDrinkingWaterConcentration forProtectionof HumanHealth(ppb)Lowest U.S. EPAAquatic Acute orChronic Benchmark(A), or Lowest OPPDatabase Value(B) Multiplied byLevel of Concern2(LOC) Factor (ppb)Test type (A) or Species/testtype (B)Lowest AquaticToxicity Value orHuman HealthProtective Level forDrinking WaterReason forexclusion fromdraft list forsurface waterregulationTerbuthylazine NA3.2B (EC50) x 1 =3.2Selenastrum capricornutum/Acute nonvascular plants3.2All uses wouldqualify forexemption dueto intentionalapplication towater.Tetrachlorvinphos1210e1.9B (EC50) x .5 =.95Daphnia magna/ Acuteinvertebrates0.95Thiobencarb 1c1A Chronic invertebrates 1Alreadyregulated toprevent driftand runoff tosurface water.Triallate 91e13A Chronic invertebrates 13John S. Sanders, Ph.D.May 29, 2009Page 23Common nameMCL orLowestDrinkingWaterConcentration forProtectionof HumanHealth(ppb)Lowest U.S. EPAAquatic Acute orChronic Benchmark(A), or Lowest OPPDatabase Value(B) Multiplied byLevel of Concern2(LOC) Factor (ppb)Test type (A) or Species/testtype (B)Lowest AquaticToxicity Value orHuman HealthProtective Level forDrinking WaterReason forexclusion fromdraft list forsurface waterregulationTribufos (Folex –S,S,S- tributylphosphorotrithioate)NA 1.56A Chronic invertebrates 1.56Triclopyr, butoxyethyl esterNA 100A (triclopyr) Acute nonvascular 100Lowest value50 ppb or moreTriclopyr,triethylamine saltNA 100A (triclopyr) Acute nonvascular 100Lowest value50 ppb or moreTrifluralin 4g1.14A Chronic fish 1.14John S. Sanders, Ph.D.May 29, 2009Page 241Single detection2Factor used by he U.S. EPA to calculateaquatic life benchmarks. See text.aCDPH and U.S. EPA MCLbU.S. EPAMCLcCDPHMCLdNational Academy of Sciences HA (noncancer)eU.S. EPA Integrated Risk Information System reference dose (noncancer)fU.S. EPA HA (noncancer)gU.S. EPA HA (cancer)hCalifornia notification levelNA=not available