Nick Poletika

EPA Public Workshop of 22 Apr 2014

SUGGESTIONS FOR GAINING EFFICIENCIES IN THE ESA 

RISK ASSESSMENT PROCESS - AN INSECTICIDE EXAMPLE
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Topical areas for consideration in the context of the 

NAS Panel report

• Use an agreed scoring system for non-guideline studies when selecting the lowest 

relevant toxicity value for the most sensitive species in the environment

• Exclude taxa with low toxicity endpoints in initial species/critical habitat overlap 

analysis when indirect effects are unimportant

• Consider all available qualified data in defining thresholds and use distributions of 

values

• Bring in more specific exposure modeling with bounding of upper end estimates 

from distributions to allow screening at national level 

• Supplement LD50/sq ft with more realistic exposure assessment for birds

• Supplement Fletcher/Kenaga nomogram with more realistic exposure (and effects) 

assessment for birds
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Use an agreed scoring system for non-guideline studies 

when selecting the lowest relevant toxicity value for the 

most sensitive species in the environment

After Giddings JM, Williams WM, Solomon KR, Giesy JP. 2014. Risks to aquatic organisms from the use of chlorpyrifos in 

the United States. Rev Environ Contam Toxicol 231:119-162.
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Benefits of using such a scoring system

• Supplements ECOTOX limitations to ensure high data quality

• High data quality results in accurate action area definition for 

species/critical habitat overlap analysis

• Provides consistency in additional steps of assessment
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Exclude taxa with low toxicity endpoints in initial species/critical 

habitat overlap analysis when indirect effects are unimportant

> Terrestrial environment most sensitive species endpoints – plant example

Taxa (of listed 

species or 

obligate species)

Endpoint Threshold Overlap Distance

(ft, max. use 

rate)

Birds LD50 = 5.62 

mg/kg

1-in-106 = 0.5 

mg/kg

>2605

Mammals (15 g) NOEL = 1 mg/kg NOEL = 1 mg/kg >2605

Reptiles LD50 = 5.62 

mg/kg

1-in-106 = 0.5 

mg/kg

>2605

Terrestrial-phase 

amphibians

LD50 = 5.62 

mg/kg

1-in-106 = 0.5 

mg/kg

>2605

Terrestrial 

invertebrates

LD50 = 0.059 

μg/bee

1-in-106 = 0.005 

μg/bee

>2605

Terrestrial plants NOEC = 0.8 lb/A NOEC = 0.8 lb/A 0
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Benefit of excluding listed terrestrial plants

• US FWS Boxscore*

> United States Total Listings

• Grand total = 1517

• Plant total = 874

• Plants represent 57.6% of all listed species

• Of this plant total, very few (any?) obligate species with dependency 

on animals for pollination or seed dispersal

• “No effect” determinations are possible for most (all?) listed plants at 

Step 1

• Recommend obligate relationships be cataloged for confirmation

* http://ecos.fws.gov/tess_public/pub/Boxscore.do
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Consider all available qualified data in defining 

thresholds and use distributions of values

Concentration (μg L-1)

10-3 10-2 10-1 100 101 102 103 104

P

r

o

p

o

r

tio

n

o

f

s

p

e

cie

s

0.0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1.0

N

O

E

C

e

c

o

1-in-a-millio

n

L

C

1

0

f

r

o

m

H

C

5
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Bring in more specific exposure modeling with 

bounding of upper end estimates from distributions to 

allow screening at national level

After Williams WM, Giddings JM, Purdy J, Solomon KR, Giesy JP. 2014. Exposures of aquatic organisms to the

organophosphorus insecticide, chlorpyrifos resulting from use in the United States. Rev Environ Contam Toxicol 231:77-118.
| 9

Bring in more specific exposure modeling that relates to 

actual habitat of listed species – Focus Area example

After Williams WM, Giddings JM, Purdy J, Solomon KR, Giesy JP. 2014. Exposures of aquatic organisms to the

organophosphorus insecticide, chlorpyrifos resulting from use in the United States. Rev Environ Contam Toxicol 231:77-118.

Cedar Creek, Leelanau County, Michigan (7,100 ha)

Dry Creek, Miller County, Georgia (12,300 ha)

Orestimba Creek, Stanislaus County, California (56,000 ha)

SWAT

PRZM

AgDRIFT

Photo Credit: McCabe, D. J. (2010) Rivers and Streams: Life in Flowing Water. Nature Education Knowledge 1(12):4
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Benefit of using more specific exposure modeling 

distributions and alternative thresholds

After Williams WM, Giddings JM, Purdy J, Solomon KR, Giesy JP. 2014. Exposures of aquatic organisms to the

organophosphorus insecticide, chlorpyrifos resulting from use in the United States. Rev Environ Contam Toxicol 231:77-118.

Explicitly, 

water 

column in 

vulnerable 

fish habitat

N

O

E

C

e

c

o

=

0.1 μ

g/L

1-in-a-millio

n

=

0.0

0

3

5

μ

g/L

L

C10

f

r

o

m

H

C

5

=

0.0

2

2

μ

g/L

“No Effect” 

using 

NOECeco

“No Effect” 

using 

NOECeco

“No Effect” 

using 

NOECeco
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Benefit of using distributions of exposure and effects

Risks from modeled exposures (CA)

Risks from modeled exposures (MI)

“No Effect” 

for Fish 

and 

Insects

“No Effect” 

for Fish,

Crustacea,

and

Insects

After Giddings JM, Williams WM, Solomon KR, Giesy JP. 2014. Risks to aquatic organisms from the use of chlorpyrifos in 

the United States. Rev Environ Contam Toxicol 231:119-162.
| 12

Supplement LD50/sq ft with more realistic exposure 

assessment for birds

• GranPARAM example

After Moore DRJ, Teed RS, Greer C, Solomon KR, Giesy JP. 2014. Refined avian risk assessment for chlorpyrifos in

the United States. Reviews of Environmental Contamination and Toxicology 231:163-217.
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Benefit of using more realistic exposure assessment for 

granular uses

• GranPARAM accounts for

> Proportion of time that birds forage for grit in treated fields

> Relative proportions of natural grit versus granules on the surface of 

treated fields

> Rate of particle ingestion

> Attractiveness of granules relative to natural grit

• Can reach the conclusion of no significant risk issues for birds for any 

granular product use pattern

• “No effect” for listed birds from granular uses
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Supplement Fletcher/Kenaga nomogram with more 

realistic exposure (and effects) assessment for birds

• LiquidPARAM example

> Incorporates parts of EPA TIM 

v1 and v2 model and many 

recommendations from SAP 

2001 and 2004 meetings

• Field studies used as an 

independent line of evidence

After Moore DRJ, Teed RS, Greer C, Solomon KR, Giesy 

JP. 2014. Refined avian risk assessment for chlorpyrifos

in the United States. Reviews of Environmental 

Contamination and Toxicology 231:163-217.
| 15

Benefit of using more realistic exposure (and effects) 

assessment for birds

• According to model results, some acute risk issues for sensitive bird 

species in higher rate use patterns

• Most bird species, however, not at significant acute risk for assessed 

use patterns

• Field results indicate that LiquidPARAM likely overestimating acute 

risk

• Chronic risk not a significant issue

• Can use listed species biology information for bird “no effect” 

determinations

> Habitat requirements in relation to specific crop in-field exposure

> Comparison to dietary profiles of focal species (next slide)
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LiquidPARAM focal species 

Killdeer (Charadrius vociferous) breeds in southern Canada, the US and northern Mexico, and 

winters in Central America, the Caribbean, Mexico, and the southern and coastal areas of the US 

(Gauvreau and Alvo 1996, Godfrey 1986); (Howell and Webb 1995, Raffaele et al. 1998). The 

diet is almost entirely arthropods with a small portion of seeds (McAtee and Beal 1924, Wetmore 

1916).

Mourning dove (Zenaida macroura) can be found throughout southern Canada, the US, central 

Mexico, Central America, and the Caribbean 47-54 (Aldrich 1993, Howell and Webb 1995, Otis 

et al. 2008, Ridgely and Gwynne 1989). The mourning dove is only a partial migrant, and 

migratory and resident populations co-exist (Chambers et al. 1962). The diet of the mourning 

dove is entirely comprised of seeds (Lewis 1993, Mirarchi 1993). 

Northern bobwhite (Colinus virginianus) is typically sedentary and non-migratory, and can be 

found in the eastern US, southern Ontario, eastern Mexico, and parts of the northern Caribbean 

(Cadman et al. 1987, Howell and Webb 1995, Raffaele et al. 1998). Adult northern bobwhites

weigh 140 to 170 g (Johnsgard 1988), and primarily consume insects and seeds (Brennan and 

Hurst 1995).

Red-winged blackbird (Agelaius phoeniceus) is a partial migrant (Dolbeer 1982) and can be 

found throughout most of North America (Howell and Webb 1995, Monroe 1968). The redwinged blackbird consumes seeds and insects (Bird and Smith 1964, McNicol et al. 1982).

Vesper sparrow (Pooecetes gramineus) breeds from sea level to 3000 m elevation (Ligon 

1961), and from the mid-latitudes of the US north to the mid-latitudes of Canada (Campbell et al. 

2001, Cannings et al. 1987, Gilligan et al. 1994, Godfrey 1986, Peck and James 1987, 

Semenchuk 1992, Smith 1996). The wintering range of the vesper sparrow spans the southern 

US and Mexico (Howell and Webb 1995, Root 1988). Males and females average 23 to 24 g 

(Jones and Cornely 2002). The vesper sparrow eats grasses, seeds and foliage-dwelling insects 

(Best 1972, Feist 1968).

Western meadowlark (Sturnella neglecta) consists of both migratory and non-migratory 

populations, and is primarily confined to central and western North America (Davis and Lanyon 

2008, Owens and Myres 1973, Rotenberry and Wiens 1980). The diet of the western 

meadowlark is mainly comprised of insects, with a small proportion of seeds and grains (Bryant 

1914, Maher 1974, Orians 1985).

Abert’s towhee (Pipilo aberti) is a non-migratory bird found in the southwestern United States 

below 1300 m elevation (Phillips et al. 1964). It averages 47.1 (males) to 44.8 (females) g in 

body mass (Dunning 1984) and feeds on insects and seeds from the ground (Rosenberg et al. 

1991).

American crow (Corvus brachyrhynchos) can be found throughout North America and consists 

of both resident and migratory individuals (Black 1941). The crow ranges in mass from 316 to 

575 g (Johnston 1961) and is an omnivorous and opportunistic ground feeder (Verbeek and 

Caffrey 2002). 

American robin (Turdus migratorius) breeds throughout most of North America and winters in 

the southernmost parts of Canada, the United States, and Central America (Godfrey 1986). 

Adults average 77 g in mass (Sallabanks and James 2002). The diet of the American robin 

comprises mainly insects and fruit, with insects, particularly earthworms, being important in the 

spring and summer (Sallabanks and James 2002, Wheelwright 1986). 

Blue grosbeak (Passerina caerulea) can be found in North America as far north as South 

Dakota and as far south as Panama (American Ornithologists’ Union 1998). It has a mean mass

of 28 g (Dunning 1993) and mainly forages on insects (Bent 1968, Martin et al. 1961). 

Common pheasant (Phasianus colchicus) is primarily found on agricultural lands in southern 

Canada and in the mid- to northern United States (American Ornithologists’ Union 1998). It is 

primarily a sedentary species, but will migrate in search of food (Olsen 1977). Males weigh 900 

to 3000 g, and females weigh 500 to 1000 g (Long 1981, Ridgway and Friedmann 1946). The 

breeding season diet of the common pheasant includes agricultural grains and other vegetation, 

insects, and seeds (Stromberg 1979).

Dickcissel (Spiza americana) breeds in central North America from North Dakota to Texas 

(American Ornithologists’ Union 1998) and winters in central Venezuela (Basili and Temple 

1999). Its diet is comprised primarily of ground-dwelling arthropods and seeds (Gross 1921, 

Temple 2002). 

Horned lark (Eremophilia alpestris) breeds throughout most of the US, Canada and Mexico, 

and winters in the US and Mexico (Godfrey 1986, Howell and Webb 1995). The diet of the 

horned lark is comprised almost entirely of seeds in the winter months, but also includes grounddwelling insects in the spring, summer and fall (Rotenberry 1980). 

Indigo bunting (Passerina cyanea) is a long-distance migrant, primarily breeding in the eastern 

US and southeastern Canada (American Ornithologists’ Union 1998) and wintering in Mexico, 

Central America, and the Caribbean (Howell and Webb 1995). The diet of the indigo bunting 

includes seeds, berries, and insects gleaned from foliage (Barrows 1912, Butler 1897, Forbes 

1883, McAtee 1926, Taber and Johston 1968). 

After Moore DRJ, Teed RS, Greer C, Solomon KR, Giesy 

JP. 2014. Refined avian risk assessment for chlorpyrifos in

the United States. Reviews of Environmental 

Contamination and Toxicology 231:163-217.

Focal species for corn: 

American robin, Horned lark, 

Killdeer, Mourning dove, 

Northern bobwhite, 

Redwinged blackbird, Vesper 

sparrow

Horned lark (Eremophilia

alpestris) breeds 

throughout most of the 

US, Canada and Mexico, 

and winters in the US 

and Mexico (Godfrey 

1986; Howell and Webb 

1995). The diet of the 

horned lark is comprised 

almost entirely of seeds 

in the winter months,

but also includes grounddwelling insects in the 

spring, summer and fall 

(Rotenberry

1980).
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Summary and Relative Implementation Costs

Suggestion Required Resources

• Study scoring system

• Exclude insensitive taxa

• Consider all data

• Specific exposure modeling

• Supplement LD50/sq ft

• Supplement nomogram

• Initially define system ($)

• Catalog obligates ($)

• SSDs ($)

• One-time scenario effort ($$$)

• Apply GranPARAM ($-$$)*

• Apply LiquidPARAM ($$-$$$)#

• Voluntary field studies ($$$)

Registrants can supply information following Agency guidance

*Or consider granule composition ($)

#Or use focal species biology ($)