OFFICE OF CHEMICAL SAFETY

AND POLLUTION PREVENTION

UNITED STATES ENVIRONMENTAL PROTECTION AGENCY

WASHINGTON, D.C. 20460

MEMORANDUM

DATE: August 23, 2011

SUBJECT: Preliminary Environmental Assessment for the Registration Review of AVI Glycine 

Hydrochloride (AVG) 

Registration Review Case #: 6070

PC Code: 129104

CAS #: 55720-26-8

Chemical Class: Biochemical

FROM: Gina M. Casciano, M.S., Biologist

Biochemical Pesticides Branch

Biopesticides & Pollution Prevention Division (7511P)

THROUGH: Mike Rexrode, Ph.D., Senior Scientist

Biochemical Pesticides Branch

Biopesticides & Pollution Prevention Division (7511P)

TO: John Fournier, Regulatory Action Leader

Biochemical Pesticides Branch

Biopesticides & Pollution Prevention Division (7511P)

ACTION REQUESTED

The following is the preliminary environmental assessment for AVI Glycine Hydrochloride (AVG), in 

support of the Registration Review Preliminary Work Plan. 
2

Executive Summary

Based on the available data, AVG is characterized as moderately toxic to avian species (acute LD50

=121 mg/kg, LC50 = 230 ppm; reproductive NOAEC = 50 ppm) and practically non-toxic to 

mammalians on an acute basis (LD50 = 6,480 mg/kg). The Rat Reproductive Toxicity study, however, 

produced a NOAEL = 2.5 mg/kg/day and a LOAEL = 4.0 mg/kg/day for F1 offspring and showed 

decreased viability of pups and retarded growth of F1 and F2 pups. Test diet was administered 

continuously for at least 70 days prior to F0 mating and during mating, gestation, and lactation until the 

litters were weaned. The F1 pups were weaned onto the same diet received by their parents. AVG is

practically non-toxic to coldwater fish (LC50 > 139 mg/L) and aquatic invertebrates (48 hr EC50 = 1.81 -

137 mg/L). AVG is also practically non-toxic to honey bees (oral and contact LD50 > 100μg/bee) and 

exposure to plants should not result in adverse effects on seedling emergence, growth, weight or 

condition. 

The Agency assessed the potential risk of AVG (0.11 lbs ai/A) to non target organisms by using the Tier 

I aquatic model, GENEEC, for evaluating exposure and to aquatic organisms and actual field residues 

for terrestrial species. All calculated RQ values were less than the Agency LOC (aquatic LOC = 0.05 –

0.5; and terrestrial LOC = 0.1 – 1.0). The Agency also has concluded a No Effect for endangered/

threatened species based on the risk assessment for non-target aquatic and terrestrial species, the 

persistence of AVG in the environment (1.7 - 4.7 days), and the application rate (50 grams/A; 0.11 lbs 

ai/A).

STUDY SUMMARIES

1.0 Environmental Chemistry and Fate Assessment

AVI glycine hydrochloride (AVG) is a plant growth regulator used on apples, pears, and ornamentals.

As a naturally occurring chemical, AVG prevents the biosynthesis of ethylene in plants by interfering 

with the functioning of the enzyme aminocyclopropanecarboxylate synthase (ACC synthase). When 

applied to apples, it may delay fruit maturity, leading to benefits such as a reduction in pre-harvest fruit 

drop and improved fruit quality. In pears, AVG may help maintain fruit firmness. For specific 

ornamentals (miniature carnations, hibiscus, and rooted geranium cuttings and seedlings), AVG may

reduce problems such as flower senescence and flower bud abscission that occur during shipping.

Registered products containing AVG are intended for use as spray solutions, applied to apples or pears 

as a single application 28 days prior to the anticipated beginning of the normal harvest period, and to 

specified ornamentals 24 to 48 hours prior to boxing/shipping. 

AVG is very soluble in water at 674 ± 23 g/L (pH =6.0), has a very low vapor pressure, and a low 

potential to volatilize. AVG is hydrolytically stable (sterile conditions) with an expected half-life of 

greater than 5days. Photodegredation data for water or soil was not available, but models indicate the 

half life of AVG in the atmosphere to be 0.7 hours during daylight and 4 hours at night (assuming ozone 

mediated decay and hydroxyl mediated decay, respectively). No data is available on leaching rates of 

AVG. 

Degradation of AVG into two major metabolites has been observed in water and soil with

ethoxyvinylglycine as the predominate degradate, and ω-N-acetyl-AVG as a slightly less predominate 

metabolite. AVG migrates rapidly from the aqueous phase to the sediment phase and strongly adsorbs

to sediment.
3

AVG is easily desorbed from soils with low clay content (humic sand and low humic content sandy 

loam) and degrades rapidly in sandy loam and loam during adsorption and desorption. Generally, AVG 

degrades rapidly in soil, with half-life ranging from 1.7 to 4.7 days depending on soil type. The half life 

for the two metabolites in soil ranged from 0.3-8.2 days. A summary of the environmental chemistry and 

fate properties for AVG appear in Table 1.0.
4

Table 1.0 Summary of AVG Environmental Chemistry and Fate Properties

Study Value (units) Major Degradates

Minor Degradates

MRID # Study Status

Sediment and Soil 

Adsorption/ 

Desorption

Sandy loam:

Kd-ads = 59.96 mL/g

Koc- ads = 7,495 mL/g

Kd-des = 76.22 mL/g

Low humic content sandy loam:

Kd-ads = 4.11 mL/g

Koc- ads = 1,028 mL/g

Kd-des = 5.18 mL/g

Loam:

Kd-ads = 73.86 mL/g

Koc- ads = 7,386 mL/g

Kd-des = 82.66 mL/g

Humic sand:

Kd-ads = 7.86 mL/g

Koc- ads = 561 mL/g

Kd-des = 18.01 mL/g

Degraded rapidly in sandy 

loam and loam during 

adsorption and desorption.

Stable during adsorption in 

low humic sand and sand, 

but some degradation 

during desorption. Two 

degradates were observed 

but were not identified.

45359607 Acceptable

Hydrolysis Hydrolytically stable at pH 7, 9. 

Slight hydrolysis (6%) at pH 4. Test 

performed at 50oC over five days.

Degradates were not 

identified. 46791701

Acceptable

Aerobic Soil 

Metabolism

Degraded very rapidly in sandy 

loam and loam soils with a half life 

of 1.7 and 2.4 days, respectively. 

Half life in humic sand and low 

humic content sand soils were 3.0 

and 4.7 days, respectively.

HPLC confirmed that 

parent degraded rapidly and 

two major metabolites were 

formed. The half life of the 

two metabolites in the four 

soil types ranged from 0.3-

8.2 days. 

46066803

Acceptable

Aerobic/Anaerobic 

aquatic 

metabolism

Moved rapidly from water column 

to sediment in an anaerobic 

sediment/aerobic water system. 

Less than 1% test substance 

remaining in aqueous phase after 9 

days of incubation.

HPLC detected two 

metabolites, which were 

identified via LC-MS/MS. 

Metabolite appearing in 

greatest quantity (and 

eluding first) was identified 

as ethoxyvinylglycine. 

Metabolite of lesser 

quantity was identified as 

ω-N-acetyl-AVG. 

45796502

45796503

Acceptable

Photodegredation

in air

Model results indicate a half life of 

0.7 hours during daylight and 4 

hours during night-time.

- 46066802 NonGuideline/ 

Acceptable

2.0 Measures of Ecological Exposure

Measures of exposure are based on aquatic and terrestrial models that predict estimated environmental 

concentrations (EECs) of a pesticide using maximum labeled application rates and methods of 

application. The use patterns for the three currently registered end-use products (EPs) containing AVG 
5

are applied as spray solutions to flowers, orchard fruit and foliage. Therefore, runoff and spray drift are 

potential transport mechanisms of AVG to non-target aquatic and terrestrial sites. However, all end-use 

product labels currently include the statement “For Terrestrial Uses: Do not apply directly to water, to 

areas where surface water is present or to intertidal areas below the mean high water mark. Do not 

contaminate water when disposing of equipment wash water or rinsate.” The maximum use rate for 

AVG on outdoor crops is 50 grams/acre applied twice pre-harvest on apples and once pre-harvest on all 

other approved crops. 

For aquatic exposure estimates, the Agency estimated environmental concentrations (EECs) of AVG 

that may impact aquatic organisms by applying a Tier I aquatic model, GENEEC Version 2.0 (Appendix 

B). Terrestrial exposure was assessed by using actual residues taken in the field (peach orchard) for a 

similar compound ABG-3168 (50 grams ai/A).

3.0 Measures of Effect

Measures of effect for AVG are obtained from the registrant-submitted guideline studies for this 

biochemical. The acute measures of effect routinely used for non-target animals in screening level 

assessments are the LD50, LC50 or EC50, depending on taxa. LD stands for "Lethal Dose", and LD50 is 

the amount of a material, given all at once, that is estimated to cause the death of 50% of a group of test 

organisms. LC stands for “Lethal Concentration” and LC50 is the concentration of a chemical that is 

estimated to kill 50% of a sample population. EC stands for “Effective Concentration” and the EC50 is 

the concentration of a chemical that is estimated to produce some measured effect in 50% of the test 

population. Endpoints for chronic measures of exposure for listed and non-listed animals are the 

NOAEL or NOAEC. NOAEL stands for “No Observed-Adverse-Effect-Level” and refers to the highest 

tested dose of a substance that has been reported to have no harmful (adverse) effects on a test 

population. The NOAEC (i.e., “No-Observed-Adverse-Effect-Concentration”) is the highest test 

concentration at which none of the observed results were statistically different from the control. 

5.0 Terrestrial Species Hazard Assessment 

Avian

An acute oral toxicity study using the technical grade of the active ingredient (TGAI) is required to 

establish the toxicity of AVG to birds. The preferred test species is either mallard duck (Anas 

platyrhynchos; a waterfowl) or Bobwhite quail (Colinus virginianus; an upland game bird). Through two

acute studies on Bobwhite quail, AVG has been shown to be moderately toxic to avian species with 

LD50 = 121 mg/kg and LC50 = 230 ppm. A chronic study in Bobwhite quail showed reproductive 

effects in the 125ppm treatments groups (decline in offspring weight), thus setting the NOAEC at 50 

ppm (Table 5.0).

Mammalian

The Agency relied on the Acute Oral Rat study (OPPTS 870.1100) and the Two-Generation Rat 

Reproduction study (OPPTS 870.3800) as surrogates for predicting the potential for mammalian hazard 

from exposure to AVG (Table 5.1). The Acute Oral LD50 for rats was calculated at > 6,480 mg/kg

suggesting that this compound is practically non toxic to mammals on an acute basis (MRID 42672203). 

The Reproductive Toxicity study, however, produced a NOAEL = 2.5 mg/kg/day and a LOAEL = 4.0 

mg/kg/day for F1 offspring and showed decreased viability of pups and retarded growth of F1 and F2

pups. Test diet was administered continuously for at least 70 days prior to F0 mating and during mating, 
6

gestation, and lactation until the litters were weaned. The F1 pups were weaned onto the same diet 

received by their parents (MRID 44946501).

Non Target Insects

AVG produced LD50 > 100μg/bee for oral and contact honey bee (Apis mellifera L.) studies, indicating 

that AVG is practically non-toxic to honey bees (Table 5.2). 

Plants

In a single pre-emergent application of 124 g a.i./ha, AVG application to corn, onion, ryegrass, wheat, 

bean, cabbage, lettuce, radish, tomato, and soybean seeds resulted in no adverse effects on seedling 

emergence, growth, weight or condition. In addition, no phytotoxicity was observed in any of the plants 

(NOEC = 124 g a.i./ha, and EC25 > 124 g a.i./ha; MRIDs 45359611 and 45359612).

Table 5.0 Summary of Avian Toxicity for AVG

Test Species % ai Endpoint 

Toxicity 

Category 

MRID No. 

Author/Year 

Study 

Classification

Acute Toxicity

Bobwhite quail

(Colinus 

virginianus)

80.6 LD50 = 121mg ai/kg Moderately toxic 43183610

Campbell et 

al.,/1993

Acceptable

Bobwhite quail

(Colinus 

virginianus)

80.6 LC50 = 230 ppm Moderately toxic 43183611

Campbell and 

Beavers, 1993.

Acceptable

Chronic Toxicity

Bobwhite quail

(Colinus 

virginianus)

88 No reproductive effects at 20 or 50 ppm. 

Effects observed at 125ppm were a 

decline in offspring body weight. 

NOAEC = 50 ppm.

45796504

Frey et 

al./2002

Acceptable

Table 5.1 Summary of Mammalian Toxicity for AVG

Study Test 

Species

Endpoint Toxicity 

Category 

MRID No. 

Author/Year 

Study 

Classification

Acute Toxicity

Acute Oral

(OPPTS 870.1100)

Rat LD50 = 6,480 mg 

ai/kg

Practically non

toxic

42672203 Acceptable

Chronic Toxicity

Two-Generation 

Reproduction study

(OPPTS 870.3800)

Rat NOAEL = 2.5 mg/kg/day and LOAEL = 

4.0 mg/kg/day for F1 offspring 

(decreased viability of pups and retarded 

growth of F1 and F2 pups).

44946501 Acceptable

Table 5.2 Toxicity of AVG to Honey Bee

Test Species % ai Endpoint 

Toxicity 

Category 

MRID No. 

Author/Year 

Study 

Classification

Honey bee

(Apis mellifera L.)

82 48 hour oral and 

contact studies:

LD50>100μg/bee for 

each study

Practically nontoxic45402204 

Wainwright/2001

Acceptable
7

6.0 Aquatic Hazard Assessment

Fish

The acute freshwater fish study available for AVG concludes that this biochemical is practically nontoxic (LC50 > 139 mg/L) to coldwater fish (Table 6.0). There are no chronic fish studies available for 

AVG.

Aquatic Invertebrates

Acute toxicity studies on Daphnia magna are equivocal, with 48 hr EC50 = 1.81 - 137 mg/L. This spans 

the range of moderate to practically non-toxic to freshwater invertebrates on an acute basis (Table 6.1). 

There are no chronic toxicity studies available for AVG in freshwater invertebrates. 

There are no studies on AVG involving estuarine or marine invertebrates.

Table 6.0 Freshwater Fish Toxicity Studies for AVG

Species % ai Results MRID Classification

Freshwater Species

Rainbow trout 

(Oncorhynchus 

mykiss) 

80.6 96hr LC50> 139mg/L 43183612 Acceptable

Table 6.1 Freshwater Invertebrates Toxicity Studies for AVG

Species % ai Effect MRID Classification

Acute Toxicity

Daphnia magna 80.6 48 hr. EC50 > 135 mg/L 43183613 Acceptable

Daphnia magna 15 48hr. EC50 = 11.9 mg/L (1.81 

mg ai/L)

45402301 Acceptable

7.0 Risk Characterization

Risk characterization is the integration of exposure and ecological effects characterization to determine 

the potential ecological risk from registered uses of AVI glycine hydrochloride (AVG) and the 

likelihood of direct and/or indirect effects to non-target aquatic and terrestrial species. For the 

screening-level portion of this assessment, the deterministic risk quotient method (RQ) is used to 

provide a metric of potential risks. The RQ is a comparison of exposure estimates to toxicity endpoints; 

estimated or actual exposure concentrations are divided by acute and chronic toxicity values. The 

resulting unit less RQs is compared to the Agency’s levels of concern (LOCs) (Table 7.0). LOCs are 

used to indicate when the use of a pesticide, as directed on the label, has the potential to cause adverse 

effects on non-target organisms.

Table 7.0 Agency Levels of Concern (LOC).

Risk Description RQ Taxa

Acute Potential for acute risk to non-target organisms 

which may warrant regulatory action in addition 

to restricted use classification

acute RQ > 0.5 aquatic animals, 

mammals, birds
8

Risk Description RQ Taxa

Acute Restricted 

Use

Potential for acute risk to non-target organisms, 

but may be mitigated through restricted use 

classification

acute RQ > 0.1 aquatic animals

acute RQ > 0.2 mammals and 

birds

Acute Listed 

Species

Listed species may be potentially affected by 

use

acute RQ > 0.05 aquatic animals 

and terrestrial 

invertebrates

acute RQ > 0.1 mammals and 

birds

Chronic Potential for chronic risk may warrant 

regulatory action, listed species may potentially 

be affected through chronic exposure

chronic RQ > 1 all animals

Non-Listed and 

Listed Plant 

Potential for effects in non-listed and listed

plants

RQ > 1 all plants

Aquatic Risk Assessment

Risk quotients (RQ) were calculated as an exposure/hazard ratio in order to determine the potential 

ecological risk from AVG exposure to non-target aquatic species. The Agency has calculated the

potential for exposure through GENEEC (Generic Estimated Environmental Concentration Model 

Version 2.0; Aug. 2001) a Tier I computer program, that uses soil/water partition coefficient and 

degradation kinetic data to estimate runoff from a ten hectare field into a one hectare by two meter deep 

"standard" pond. This first tier is designed as a coarse screen and estimates conservative pesticide 

concentrations in surface water from a few basic chemical parameters and pesticide label use and 

application information. Tier I is used to screen chemicals to determine which ones potentially pose 

sufficient risk to warrant higher level modeling. GENEEC is a program to calculate acute as well as 

longer-term estimated environmental concentration (EEC) values. It considers reduction in dissolved 

pesticide concentration due to adsorption of pesticide to soil or sediment, incorporation, degradation in 

soil before wash off to a water body, direct deposition of spray drift into the water body, and degradation 

of the pesticide within the water body (Appendix B). The acute risk to freshwater fish and invertebrates 

form AVG exposure is not expected to be an environmental concern (RQ = 0.00), all RQ values are 

below the Agency LOC values (Table 8.0).

Table 8.0 GENEEC (Version 2.0) EEC Values (ppb) for AVG Application to Peaches (0.11 lbs. 

ai/A, One Applications/Year) and Acute RQ Values Calculated for Fish and Aquatic Invertebrates

Species Toxicity End

Point

Peak EEC (ppb) RQ

(acute)

4 Day EEC 

(ppb)

RQ

(acute)

Acute Exposure LOC = 0.05 – 0.5

Rainbow trout 

(Oncorhynchus mykiss) 

96 hr LC50 > 139 

mg/L

1.18 0.00 1.10 0.00

Daphnia magna 48 hr EC50 > 135 

mg/L

1.18 0.00 1.10 0.00
9

Terrestrial Risk Assessment

The Agency assessed the potential risk to terrestrial species from AVG exposure by evaluating actual 

field residues of ABG-3168 (S-trans-2-amino-4-(2-aminoethoxy)-3-butenoic acid hydrochloride) on 

peaches (Table 8.1). This compound is similar to AVG and also acts as a fruit ripening inhibitor with a 

treatment rate of 50 g active ingredient per acre (0.11 lbs ai) administered through a spray application to 

peach trees. Residues were collected at the day of application, as well as, 3, 5, 7, 9, 11, and 14 days post 

application. Based on avian and mammalian toxicity data and one application per year (ABG-3168; 15% 

ai) the Agency calculated potential acute and chronic RQs to these species.

Table 8.1 Residues Collected for ABG-3168 (15% ai)

Date Sampled Days Post 

Application

Residues Found for Parent

(ppm)

Residues for 15% ai

(ppm)

6/02/99 0 0.29 – 0.39 0.04 – 0.06

6/05/99 3 0.21 – 0.31 0.03 – 0.05

6/07/99 5 0.13 – 0.14 0.02 – 0.02

6/09/99 7 0.10 – 0.09 0.01 – 0.01

6/11/99 9 0.06 – 0.06 0.01 – 0.01

6/13/99 11 0.03 – 0.04 0.00 – 0.01

6/16/99 14 < Level of Detection < Level of Detection

The acute and chronic risk to terrestrial species form AVG exposure is not expected to be an 

environmental concern (RQ = 0.00), all RQ values are below the Agency LOC values (Table 8.2)

Table 8.2 Acute and Chronic RQ Values Calculated for Avian and Mammalian Exposure to One 

Application of ABG-3168 (15% ai)

Species Toxicity End

Point

Peak 

Residue

(ppm)

RQ

(acute)

3 Day 

Residue

(ppm)

RQ

(acute)

7 Day 

Residues

(ppm)

RQ

(chronic)

Acute Avian Exposure LOC = 0.1 – 0.5

Bobwhite quail

(Colinus virginianus)

LD50 = 121mg 

ai/kg 0.06 0.00 0.05 0.00

Chronic Avian Exposure LOC = 1.0

Bobwhite quail

(Colinus virginianus

NOAEC = 50 

ppm. 0.01 0.00

Acute Mammalian Exposure LOC = 0.1 – 0.5

Rat LD50 = 6,480 mg 

ai/kg

0.06 0.00 0.05 0.00

Chronic Mammalian Exposure LOC = 1.0

Rat LOAEL = 4.0 mg

ai/kg/day

0.01 0.00

Risk to Terrestrial Endangered Species

The Agency used surrogate toxicity information on the rat and Bobwhite quail and actual field residues 

(ABG-3168 applied to peaches) order to assess possible risk to terrestrial species from exposure to 

AVG. RQ values for acute avian and mammalian were at 0.00. These low RQ values combined with 

information that AVG degrades rapidly in the environment (about 1.7 – 4.7 days) shows that residues 

will not exceed the Agency’s LOC =0.1 for avian and mammalian endangered species concerns. 
10

The Agency has also calculated the potential risk to endangered/threatened terrestrial species by relying 

on the Individual Effects Model Version 1.1 (Table 8.3) that predicts the chance of individual effect at 

about 1 in 1,610,000,000,000,000. Based on the avian and mammalian toxicity data that has been 

submitted on the active ingredients, there should not be toxic risk to endangered/ threatened species 

from exposure to the end use product. AVG should present a No Effect to terrestrial threatened or 

endangered species, if used in accordance with approved labeling.

Table 8.3 Individual Effects Chance Model for Predicting the Chance of Individual Effects of 

AVG to Terrestrial Endangered Species

Risk to Aquatic Endangered Species

Acute risk to endangered/threatened freshwater fish and invertebrates from AVG (0.11 lbs ai/A) 

exposure is not expected The Agency has also calculated the potential risk to endangered/threatened 

aquatic species by relying on the Individual Effects Model Version 1.1 (Table 8.4) that predicts the 

chance of individual effect at about 1 in 418,000,000. Based on the fish and aquatic invertebrate toxicity

data on the active ingredients, there should not be toxic risk to endangered/ threatened species from 

exposure to the end use product. AVG should present a No Effect to aquatic threatened or endangered 

species, if used in accordance with approved labeling.

IEC V1.1 - Individual Effect Chance Model Version 1.1

Predictor of chance of individual effect using probit dose-response curve slope and median lethal estimate 

Enter LC50 or LD50 121

Enter desired threshold 0.1

Enter slope of dose-response 8

z score result -8 z is the standard normal deviate

Probability associated with z 6.22E-16 Uses Excel NORMDIST function to estimate P w ith low er reporting limit of 1.0 E-16

Chance of individual effect, ~1 in . . . 1.61E+15 Calculated as 1/P

This is based on the formula logLCk = logLC50+(z/b)

where: z is the standard normal deviate and b equals slope

Works for dose-response models based on a probit assumption (i.e. log normal distribution of individual sensitivity)

Note: Excel cannot calculate probabilities for extremes in z scores beyond -8.2

 Probability is defaulted to 10-16, w hich is the limit of Excel reporting.

Ed Odenkirchen, June 22, 2004 EFED/OPP/USEPA

Reset Model
11

Table 8.4 Individual Effect Chance Model for Predicting Effects to Aquatic Endangered Species 

after exposure to AVG

Conclusions

The Agency assessed the potential risk of AVG (0.11 lbs ai/A) to non target organisms by using the Tier 

I aquatic model, GENEEC, for evaluating exposure and to aquatic organisms and actual field residues 

for terrestrial species. All calculated RQ values were less than the Agency LOC (aquatic LOC = 0.05 –

0.5; and terrestrial LOC = 0.1 – 1.0). If used according to label instructions, exposure to this compound 

will not have a toxic impact on non target species. The Agency also has concluded a No Effect for 

endangered/ threatened species based on the risk assessment for non target aquatic and terrestrial 

species, the persistence of AVG in the environment (1.7 - 4.7 days), and the application rate (50 

grams/A; 0.11 lbs ai/A).

IEC V1.1 - Individual Effect Chance Model Version 1.1

Predictor of chance of individual effect using probit dose-response curve slope and median lethal estimate 

Enter LC50 or LD50 139

Enter desired threshold 0.05

Enter slope of dose-response 4.5 Is this a default slope estimate? Yes or No

z score result -5.85463498 z is the standard normal deviate

Probability associated with z 2.39E-09 Uses Excel NORMDIST function to estimate P w ith low er reporting limit of 1.0 E-16

Chance of individual effect, ~1 in . . . 4.18E+08 Calculated as 1/P

This is based on the formula logLCk = logLC50+(z/b)

where: z is the standard normal deviate and b equals slope

Works for dose-response models based on a probit assumption (i.e. log normal distribution of individual sensitivity)

Note: Excel cannot calculate probabilities for extremes in z scores beyond -8.2

 Probability is defaulted to 10-16, w hich is the limit of Excel reporting.

Ed Odenkirchen, June 22, 2004 EFED/OPP/USEPA

Reset Model
12

Appendix A. The Risk Quotient Method and Levels of Concern

Risk characterization integrates the results of the exposure and ecotoxicity data to evaluate the 

likelihood of adverse ecological effects. The means of this integration is called the quotient method. 

Risk quotients (RQs) are calculated by dividing exposure estimates by acute and chronic ecotoxicity 

values. 

RQ = EXPOSURE/TOXICITY

RQs are then compared to OPP's levels of concern (LOCs). These LOCs are used by OPP to 

analyze potential risk to nontarget organisms and the need to consider regulatory action. The criteria 

indicate that a pesticide used as directed has the potential to cause adverse effects on nontarget 

organisms. LOCs currently address the following risk presumption categories: (1) acute risks -

regulatory action may be warranted in addition to restricted use classification, (2) acute restricted use -

the potential for acute risk is high, but may be mitigated through restricted use classification, (3) acute 

endangered species - endangered species may be adversely affected, and (4) chronic risk - the potential 

for chronic risk is high regulatory action may be warranted. Currently, EFED does not perform 

assessments for chronic risk to plants, acute or chronic risks to insects, or chronic risk from 

granular/bait formulations to birds or mammals.

The ecotoxicity test values (measurement endpoints) used in the acute and chronic risk quotients 

are derived from required studies. Examples of ecotoxicity values derived from short-term laboratory

studies that assess acute effects are: (1) LC50 (fish and birds), (2) LD50 (birds and mammals), (3) EC50

(aquatic plants and aquatic invertebrates) and (4) EC25 (terrestrial plants). Examples of toxicity test 

effect levels derived from the results of long-term laboratory studies that assess chronic effects are: (1) 

LOAEL or LOAEC (birds, fish, and aquatic invertebrates) and (2) NOAEL or NOAEC (birds, fish and 

aquatic invertebrates). For birds, mammals, fish and aquatic invertebrates the NOAEL or NOAEC 

generally is used as the ecotoxicity test value in assessing chronic effects, although other values may be 

used when justified. Risk presumptions and the corresponding RQs and LOCs, are tabulated below.
13

Table 1. Risk presumptions for terrestrial animals based on risk quotients (RQ) and levels of concern (LOC).

Risk Presumption RQ LOC

Birds

Acute Risk EEC1/LC50 or LD50/ft2or LD50/day30.5

Acute Restricted Use EEC/LC50 or LD50/ft2or LD50/day (or LD50 < 50 mg/kg) 0.2

Acute Endangered Species EEC/LC50 or LD50/ft2or LD50/day 0.1

Chronic Risk EEC/NOAEC 1

Wild Mammals

Acute Risk EEC/LC50 or LD50/ft2or LD50/day 0.5

Acute Restricted Use EEC/LC50 or LD50/ft2or LD50/day (or LD50 < 50 mg/kg) 0.2

Acute Endangered Species EEC/LC50 or LD50/ft2or LD50/day 0.1

Chronic Risk EEC/NOAEC 1

1

 abbreviation for Estimated Environmental Concentration (ppm) on avian/mammalian food items

2

 mg/ft2

3

 mg of toxicant consumed/day

 LD50 * wt. of bird

 LD50 * wt. of bird 

Table 2. Risk presumptions for aquatic animals based on risk quotients (RQ) and levels of concern (LOC).

Risk Presumption RQ LOC

Acute Risk EEC1/LC50 or EC50 0.5

Acute Restricted Use EEC/LC50 or EC50 0.1

Acute Endangered Species EEC/LC50 or EC50 0.05

Chronic Risk EEC/NOAEC 1

1

 EEC = (ppm or ppb) in water

Table 3. Risk presumptions for plants based on risk quotients (RQ) and levels of concern (LOC).

Risk Presumption RQ LOC

Terrestrial and Semi-Aquatic Plants 

Acute Risk EEC1/EC25 1

Acute Endangered Species EEC/EC05 or NOAEC 1

Aquatic Plants

Acute Risk EEC2/EC50 1

Acute Endangered Species EEC/EC05 or NOAEC 1

1

 EEC = lbs ai/A 

2

 EEC = (ppb/ppm) in water 
14

Appendix B. GENEEC Run for AVG Application to Peaches

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 RATE (#/AC) No.APPS & SOIL SOLUBIL APPL TYPE NO-SPRAY INCORP

 ONE(MULT) INTERVAL Koc (PPM ) (%DRIFT) (FT) (IN)

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 .110( .110) 1 1 4028.0 4121.0 ORCHAR ( 9.7) .0 .0

 FIELD AND STANDARD POND HALFLIFE VALUES (DAYS)

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 METABOLIC DAYS UNTIL HYDROLYSIS PHOTOLYSIS METABOLIC COMBINED

 (FIELD) RAIN/RUNOFF (POND) (POND-EFF) (POND) (POND)

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 4.70 0 N/A .70- 86.80 9.00 8.15

 GENERIC EECs (IN MICROGRAMS/LITER (PPB) Version 2.0 Aug 1, 2001

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 PEAK MAX 4 DAY MAX 21 DAY MAX 60 DAY MAX 90 DAY

 GEEC AVG GEEC AVG GEEC AVG GEEC AVG GEEC

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 1.18 1.10 .72 .35 .24