Methods for Incorporating Methods for Incorporating Aquatic Plant Effects into Aquatic Plant Effects into

Community Level Community Level BenchmarksBenchmarks

EPA Development TeamEPA Development Team

Regional Stakeholder Meetings Regional Stakeholder Meetings January 11-22, 2010January 11-22, 2010

OutlineOutline Purpose and Scope

Existing data requirements and approaches for estimating aquatic plant effects

Key research questions/issues

Evaluation of approaches

Purpose and ScopePurpose and Scope

Consider existing approaches used by OW and OPP for characterizing plant aquatic ecological effects

Describe the best integrated use of existing tools for incorporating plant effects into for incorporating plant effects into aquatic community-level benchmarks.

Characterize the uncertainty and robustness of current data for aquatic plants

OPP’s Approach to OPP’s Approach to Evaluate Aquatic Plant Evaluate Aquatic Plant

EffectsEffects Tier I (Limit test)Tier I (Limit test) Needed for all pesticides with outdoor usesNeeded for all pesticides with outdoor uses 4 microalgae + 4 microalgae + Lemna:Lemna: laboratory tests with Technical Grade laboratory tests with Technical Grade

Active Ingredient (TGAI)Active Ingredient (TGAI) If >50% effect, Tier II testing requiredIf >50% effect, Tier II testing required

Tier II (Dose-response test)Tier II (Dose-response test) Pesticides that are known phytotoxins also tested at Tier IIPesticides that are known phytotoxins also tested at Tier II 4 microalgae + 4 microalgae + Lemna:Lemna: laboratory tests with TGAI laboratory tests with TGAI If >50% effect, Tier III testing may be requiredIf >50% effect, Tier III testing may be required

Tier III (Field test)Tier III (Field test) 4 vascular plant families, 3 seedless vascular plant families, 4 vascular plant families, 3 seedless vascular plant families,

10+ families of algae, 1 bryophyte family tested with typical 10+ families of algae, 1 bryophyte family tested with typical end-use product to determine detrimental effects at critical end-use product to determine detrimental effects at critical growth stagesgrowth stages

Rarely required by the AgencyRarely required by the Agency

Typical Aquatic Plant Typical Aquatic Plant Surrogates Surrogates

Used in US Regulatory Used in US Regulatory TestingTesting

Pseudokirchneriella subcapitataPseudokirchneriella subcapitata Anabaena flos-aquaeAnabaena flos-aquae

Skeletonema costatumSkeletonema costatumNavicula pelliculosaNavicula pelliculosa

Lemna gibba, a free-floating vascular macrophyte

Non-vascular plantsNon-vascular plants

OW’s Approach to OW’s Approach to Evaluate Aquatic Plant Evaluate Aquatic Plant

EffectsEffects Minimal plant data are required for the derivation of Minimal plant data are required for the derivation of Water Quality Criteria (typically not used since less Water Quality Criteria (typically not used since less sensitive)sensitive)

““Results of tests with plants usually indicate that Results of tests with plants usually indicate that criteria which adequately protect aquatic animals and criteria which adequately protect aquatic animals and their uses will probably also protect aquatic plants and their uses will probably also protect aquatic plants and their uses.” their uses.” May not be supported when addressing certain chemical May not be supported when addressing certain chemical

classes (e.g., herbicides)classes (e.g., herbicides) Plant value based on a 96-hr test conducted with an Plant value based on a 96-hr test conducted with an

alga or a chronic test conducted with an aquatic alga or a chronic test conducted with an aquatic vascular plantvascular plant

Final Plant Value: lowest value from a test with an Final Plant Value: lowest value from a test with an “important” plant species where test concentrations are “important” plant species where test concentrations are measured, and endpoint is biologically “important”.measured, and endpoint is biologically “important”.

Approaches Used Approaches Used InternationallyInternationally

Canada Canada At least one vascular plant or alga to derive At least one vascular plant or alga to derive

guidelines (if the compound is highly phytotoxic, 4 guidelines (if the compound is highly phytotoxic, 4 species are required) species are required)

Safety factorsSafety factors 10 applied for LOEC10 applied for LOEC 100 for acute data on persistent chemicals100 for acute data on persistent chemicals 20 for acute data on non-persistent chemicals 20 for acute data on non-persistent chemicals

European Union European Union Requires a green algae test (for herbicides, tests on Requires a green algae test (for herbicides, tests on

an alga and a vascular plant)an alga and a vascular plant) Safety factor of 10 to the lowest plant test valueSafety factor of 10 to the lowest plant test value

State Approach (MN)State Approach (MN) Protect overall integrity of plant community from Protect overall integrity of plant community from

significant impacts; protect the most sensitive speciessignificant impacts; protect the most sensitive species For 2 herbicides: target 20For 2 herbicides: target 20thth percentile level of percentile level of

protectionprotection Acute criterion derived using Great Lakes Initiative Acute criterion derived using Great Lakes Initiative

Tier II methodology with standard animal dataTier II methodology with standard animal data Chronic criterion derived using distribution of plant Chronic criterion derived using distribution of plant

data only data only Both ECBoth EC5050 values and/or maximum acceptable toxic values and/or maximum acceptable toxic

concentration (MATCs) were collected and put in concentration (MATCs) were collected and put in separate distributions; distributions with most robust separate distributions; distributions with most robust data set were used to derive criteriadata set were used to derive criteria 55thth percentile of EC percentile of EC5050 distribution distribution 2020thth percentile of MATC distribution percentile of MATC distribution

Key IssuesKey Issues

Minimum/type of data requirements to Minimum/type of data requirements to document aquatic plant sensitivitydocument aquatic plant sensitivity

aquatic plant grouping into subsets to draw better surrogatesaquatic plant grouping into subsets to draw better surrogates representativeness of current microalgal species for non-vascular representativeness of current microalgal species for non-vascular

plantsplants representativeness ofrepresentativeness of Lemna Lemna for aquatic macrophytesfor aquatic macrophytes

Endpoint selection Endpoint selection The appropriateness of the current plant measurement end points The appropriateness of the current plant measurement end points

(ECx versus NOAEC)(ECx versus NOAEC) Specific measurement endpoint-related questionsSpecific measurement endpoint-related questions

MiscellaneousMiscellaneous

Key IssuesKey Issues

1.1. Types/Minimum Data to Document Types/Minimum Data to Document SensitivitySensitivity

Do we need to group aquatic plants into Do we need to group aquatic plants into new subsets to draw better surrogatesnew subsets to draw better surrogates

Non-vascular vs. vascular (currently used)Non-vascular vs. vascular (currently used) HabitatHabitat Life history patterns Life history patterns PhysiologyPhysiology

Key IssuesKey Issues Are the sensitivities of current microalgal Are the sensitivities of current microalgal

species representative of non-vascular species representative of non-vascular plant sensitivities? plant sensitivities? Limited information available for comparison Limited information available for comparison

of sensitivities of standard algal species to of sensitivities of standard algal species to other non-vascular families such as mosses other non-vascular families such as mosses and liverwortsand liverworts

Many tests compared sensitivities of various Many tests compared sensitivities of various freshwater microalgal species - great variation freshwater microalgal species - great variation (2 to 10 orders of magnitude) between species (2 to 10 orders of magnitude) between species for same toxicant for same toxicant

Sensitivities of freshwater vs. saltwater algae Sensitivities of freshwater vs. saltwater algae are not well understoodare not well understood

Key IssuesKey Issues

Is the sensitivity of Is the sensitivity of LemnaLemna representative of vascular plants representative of vascular plants sensitivity? sensitivity? LemnaLemna, a free floater, may not be a , a free floater, may not be a

suitable surrogate to represent the suitable surrogate to represent the diversity of types of aquatic vascular diversity of types of aquatic vascular plants (emergent, submerged, rooted plants (emergent, submerged, rooted floating, and free floating)floating, and free floating)

Many vascular plants are rooted in the Many vascular plants are rooted in the sediment, which could provide another sediment, which could provide another route of exposureroute of exposure

Key IssuesKey Issues2.2. Endpoint SelectionEndpoint Selection

Appropriateness of ECx vs. point estimates Appropriateness of ECx vs. point estimates such as NOEC/MATCsuch as NOEC/MATC

Are plant endpoints acute or chronic?Are plant endpoints acute or chronic? Use of plant and animal data in the same Use of plant and animal data in the same

SSDSSD Use of non-traditional endpoints Use of non-traditional endpoints Inclusion of reproduction-based endpointsInclusion of reproduction-based endpoints Can endpoints from different test methods, Can endpoints from different test methods,

test durations, and light intensities be test durations, and light intensities be combined? If so how?combined? If so how?

Key IssuesKey Issues

3. Miscellaneous3. Miscellaneous How should plant recovery be incorporated?How should plant recovery be incorporated?

Exponential growth over short periods vs. aquatic Exponential growth over short periods vs. aquatic animal life cycle and reproductive strategies animal life cycle and reproductive strategies

Current frequency and duration for acute and chronic Current frequency and duration for acute and chronic effects to aquatic animals is once in 3 years – effects to aquatic animals is once in 3 years – appropriate for plants?appropriate for plants?

How to address community level impactsHow to address community level impacts Community shifts?Community shifts? Other measures?Other measures?

Strategy for Addressing Key Strategy for Addressing Key IssuesIssues

Toxicity data of at least 2 herbicides Toxicity data of at least 2 herbicides with “large” data sets will be utilizedwith “large” data sets will be utilized

What approaches to take when only What approaches to take when only OPP data are available? OPP data are available?

What approaches to take when more What approaches to take when more data are available?data are available?

Application of safety factors? (as used Application of safety factors? (as used by Canada, EU/Denmark etc.) – are by Canada, EU/Denmark etc.) – are there other factors that are more there other factors that are more scientifically defensible?scientifically defensible?

Summary Aquatic plant testing needs are Aquatic plant testing needs are

becoming more apparent. becoming more apparent. Key issuesKey issues

Representativeness of current tested species Representativeness of current tested species Determining minimum data setDetermining minimum data set Potential use of safety factorsPotential use of safety factors Use of non-traditional or reproductive endpointsUse of non-traditional or reproductive endpoints

Issues discussed in white paper will Issues discussed in white paper will need to be readdressed in the future. need to be readdressed in the future.