Background and Overview of 

Methods for Characterizing Effects 

of Pesticides on Aquatic Organisms

Background and Overview of 

Methods for Characterizing Effects 

of Pesticides on Aquatic Organisms

Kris Garber, Office of Pesticide Programs

Joe Beaman, Office of Water

1

Presentation to the FIFRA Scientific Advisory Panel 

January 31, 2012
Outline

• Common Effects Project Description

• Current Methods

• OPP Ecological Risk Assessments

• OW Method – 1985 Guidelines

• Great Lakes Initiative (GLI) Water Quality Guidance

• Methods Considered

2
Common Effects Project

• Joint Effort of OPP, OW and ORD

• Goal: Provide a common basis for OPP and OW to 

characterize aquatic effects of pesticides 

• Emphasis is on use of datasets of varying sizes ranging 

from those used by OPP for FIFRA registration to larger 

amounts of data required by OW for aquatic life criteria 

derivation

3
Common Effects Project

• Focus

• Evaluation of existing tools and approaches for estimating 

and characterizing effects to aquatic life

• Evaluate tools for potential utility for estimating toxicity 

values for unfulfilled data requirements

• Evaluate approaches for potential utility to estimate HC5 

for aquatic animal and plant communities using varying 

amounts of data

• Ensure scientific defensibility and utility of tools and 

approaches by both stakeholders and EPA.

4
Common Effects Project

• Initiated as a result of concerns over detections of 

pesticides in surface waters (USGS Report) 

• OPP evaluates ecotoxicity data and develops 

endpoints for pesticides according to FIFRA 

• Method differs from OW evaluation of effects on aquatic 

community according to CWA for developing criteria

• Stakeholder concern over potential differences in 

aquatic effects assessments conducted by OPP 

and OW

5
Common Effects Project

• Work Products

• Scoping document - 2009

• 3 White Papers (2010) – Predictive tools, Methods to 

develop benchmarks for aquatic animals

• White paper for SAP

• Outreach to stakeholders

• 6 Regional Meetings – January 2010

• National Meeting in DC – December 2010

• Docket established for submission of comments

• Currently developing guidelines for reviewing open 

literature toxicity studies 6
Overview of Risk Assessment Process

Office of Water Office of Pesticide Program

Statutory Basis CWA FIFRA

Framework for Ecological Risk 

Assessment

Effects Characterization Effects Characterization Exposure Char.

Analysis

Data Requirements Data Requirements

Common 

Effects 

Project

7

Criteria Issuance - EPA

Risk Estimation

Risk Description

Analysis

Risk 

Characterization

Risk Management

Criteria Implementation – State Adoption of WQS 

(Exposure)

Risk-Benefit Determination

Label Requirements

Criteria Development
Risk Class Risk Description RQ LOC

Acute - Animal Potential for effects to non-listed animals 

from acute exposures Peak EEC/LC50 0.5

Acute - Listed 

Animal

Federally-listed endangered and 

threatened (listed) species may be Peak EEC/LC50 0.05

Current OPP Method: 

Ecological Risk Assessment

8

Animal threatened (listed) species may be 

potentially affected by acute exposures

Peak EEC/LC50 0.05

Chronic - Animal Potential for effects to non-listed and 

listed animals from chronic exposures 

60-day EEC/NOEC (fish)

21-day EEC/NOEC 1

(invertebrates)

Non-Listed Plant Potential for effects to non-target, nonlisted plants from exposuresEEC/ EC50

1

Listed Plant Potential for effects to non-target, listed 

plant species from exposures

EEC/ NOEC or EC05 1
• RQs are based upon most sensitive 

endpoints for taxa

Current OPP Method: 

Ecological Risk Assessment

• Data obtained from registrant 

submissions and open literature

9
• FIFRA Data Requirements

• Aquatic Animals

• Acute and chronic data required for fish 

Current OPP Method: 

Ecological Risk Assessment

• Acute and chronic data required for fish 

and invertebrates

• Aquatic Plants (“FIFRA-5”)

• 4 species of algae

• 1 vascular species (duckweed)

10
OPP’s typical test species: 

FW aquatic animals

Rainbow trout Bluegill 

sunfish

Daphnia magna

11
Anabaena flos-aquae

FIFRA-5

OPP’s typical test species: 

aquatic plants

Navicula pelliculosa

Skeletonema costatum

Anabaena flos-aquae

Lemna gibba

Pseudokirchneriella subcapitata

12
• Species sensitivity distributions 

sometimes used to characterize effects

Current OPP Method: 

Ecological Risk Assessment

• Acute-chronic ratios (ACRs) commonly 

used for predicting chronic effects

13
• Based on OPP’s LOCs and taxaspecific toxicity endpoints

• May be used to interpret effects of 

pesticides with no existing Aquatic 

OPP Aquatic Life Benchmarks

Life Criteria

• Non-regulatory values under CWA 

or FIFRA

14
“1985 Guidelines”

 “Guidelines for Deriving Numerical National Water Quality 

Criteria for the Protection Of Aquatic Organisms and Their 

Uses” Stephan et.al.1985 

 Provides a structured methodology

 Allows derivation of acute criteria from short duration toxicity 

test (lethal concentration – LC50 test (lethal concentration – LC50) survival ) survival data

 Allows derivation of chronic criteria from longer duration 

toxicity test data –survival, growth and reproduction

 Hypothesis Testing –

 Point-Estimate effects concentrations Lowest Observed Effect 

Concentration – LOEC) and No Observed Effect Concentration –

NOEC)

 Statistical toxic-effect endpoints –

 “Effects Concentration X Percent” - e.g. EC20

15
Current OW Method:

Derivation of Aquatic Life Criteria

1. SALMONID 2. SECOND

FISH

FAMILY

3. 3rd CHORDATE

FAMILY

4. PLANKTONIC 5. BENTHIC CRUSTACEAN

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4. PLANKTONIC

CRUSTACEAN

5. BENTHIC CRUSTACEAN

6. AQUATIC INSECT 7. ANOTHER PHYLUM

EXAMPLES -

ANNELIDA, 

MOLLUSCA, 

ROTIFERA

8. ANOTHER INSECT

ORDER OR A 4

th

PHYLUM 

EXAMPLE 

ANNELIDA

Minimum Data

Requirements

Freshwater

Acute
Current OW Method: 

FAV CALCULATION

Step 1.

Calculate

SMAVs

Step 1

Vs

Step 3

Rank 

Order

GMAVs

Rank 

GMAVs

Step 4.

Calculate 

FAV

Using 4

Lowest 

GMAVs

Step 2

Calculate

GMAVs

SMAV Spp 1 N

LEAST

17

GMAVs SMAV Spp 1 GMAVs GMAV

FAV

1 MOST

N

S

E

N

S

I

T

I

V

I

T

Y

T

O

L

E

RAN

C

E

RAN

K

MOST

LEAST
Current OW Method:

Derivation of Aquatic Life Criteria

Species Sensitivity Distribution

Uses Genus-level

acute toxicity data (GMAV) 

18

Regression Analysis on 4 

GMAVs closest to 5th percentile

Final Acute Value (FAV) derived 

from the 5th percentile (hazard 

concentration [HC5]) value in a 

species sensitivity distribution 

FAV/2 = Acute Criterion

4 lowest GMAVs
Current OW Method:

Derivation of Aquatic Life Criteria

• Chronic criteria typically estimated using the FAV 

and Acute-Chronic Ratios (ACR)

• The ACR is a tool to estimate the final chronic value 

using the relationship between the acute and chronic 

toxicity of a chemical

• Three data requirements 

• One ACR must be from a fish

• One ACR must be from an invertebrate

• One ACR must be from an acutely sensitive 

species 19
Current OW Method

Plants – Final Plant Value

“Results of at least one 

acceptable test with a saltwater 

[freshwater] alga or vascular 

plant.”*

FIFRA-5 minimum aquatic plant requirement exceeds 

“requirement” in the OW 1985 Guidelines for Aquatic Life 

Criteria

20

Anabaena flos-aquae

plant.”*

“If plants are among the aquatic organisms most 

sensitive to the material, results of a test with a plant in 

another phylum (division) should also be available.”
Great Lakes Initiative Guidance

• Provides guidance for two sets of values

• Tier I 

• developed according to1985 Guidelines

• Tier II 

• Data sets that don’t meet MDRs of 1985 Guidelines

• Uses extrapolation factors (based on Host et al. 1995)

• Values that are conservative approximations of an FAV calculated 

using the 1985 Guidelines

21

# of MDRs met Extrapolation Factor

1 (Daphnid) 21.9

2 13.0

3 8.0

4 7.0

5 6.1

6 5.2

7 4.3
Great Lakes Initiative Guidance

• Hypothetical Tier II values for 3 pesticides

• Assuming only typical FIFRA species are available

• Tier II values calculated by dividing endpoint for most sensitive 

endpoint (for a genus) by EF for 3 MDRs (8.0) to derive Secondary 

Acute Value

• Divide SAV/2 to derive Tier II Value

22

Parameter (ppb) Acrolein Carbaryl Diazinon

SMAV – D. magna 51 7.5 1.05

SMAV- Rainbow trout 16 860 426

SMAV – Bluegill sunfish 27 6970 460

Secondary Acute Value 2.0 0.94 0.13

Tier II Value 1.0 0.47 0.065
Great Lakes Initiative Guidance

• Hypothetical Tier II values for 3 pesticides

• Assuming only typical FIFRA species are available

• Tier II values calculated by dividing endpoint for most sensitive 

endpoint (for a genus) by EF for 3 MDRs (8.0)

23

Parameter (ppb) Acrolein Carbaryl Diazinon

SMAV – D. magna 51 7.5 1.05

SMAV- Rainbow trout 16 860 426

SMAV – Bluegill sunfish 27 6970 460

Secondary Acute Value 2.0 0.94 0.13

FAV (1985 Guidelines) 5.9 4.02 0.34

Within a 

factor of 5
Methods Considered

WEBICE

QSAR 24

Lemna gibba
Methods Considered

0.5

0.6

0.7

0.8

0.9

1

p

r

o

p

o

r

tio

n

25

0

0.1

0.2

0.3

0.4

0.5

-2 0 2 4 6

Log10 EC50 (ppb)

p

r

o

p

o

r

tio

n
Methods Considered

0.5

0.6

0.7

0.8

0.9

1

p

r

o

p

o

r

tio

n

0.5

0.6

0.7

0.8

0.9

1

p

r

o

p

o

r

tio

n

26

0

0.1

0.2

0.3

0.4

0.5

-2 0 2 4 6

Log10 EC50 (ppb)

p

r

o

p

o

r

tio

n

0

0.1

0.2

0.3

0.4

0.5

-2 0 2 4 6

p

r

o

p

o

r

tio

n
Methods Considered

0.5

0.6

0.7

0.8

0.9

1

p

r

o

p

o

r

tio

n

27

0

0.1

0.2

0.3

0.4

0.5

-2 0 2 4 6

Log10 EC50 (ppb)

p

r

o

p

o

r

tio

n
Presentations

• Potential Use of Predictive Toxicology Tools in 

Characterizing Effects of Chemical Stressors to Aquatic 

Animals 

• Chris Russom

• Analysis of Species Sensitivity Distributions for Estimation 

of Acute Hazard Concentrations to Aquatic Animals 

• Matthew Etterson

• Extrapolation Factors for Derivation of Acute Aquatic Life 

HC5s: Emphasis on Acetylcholinesterase Inhibitors 

• Russell Erickson

28
Presentations

• Analysis of Chronic Toxicity Data and Acute Chronic 

Ratios (ACRs) in Support of Deriving Chronic HC5s: 

Acetylcholinesterase Inhibitors 

• David Mount

• Estimating Aquatic Plant Community Hazard 

Concentrations for Pesticide Effects 

• Glen Thursby

29