UNITED STATES ENVIRONMENTAL PROTECTION AGENCY

MEMORANDUM

DATE: March 27, 2012

SUBJECT: Tolclofos-methyl

Proposed Seed Treatment Use

PC Code: 128905

Decision No.: 443921

Petition No.: NA

Case No.: NA

TXR No.: NA

MRID No.: NA

FROM: Shalu Shelat, Industrial Hygienist 

Risk Assessment

Health Effects Division (7509P)

THROUGH: Charles Smith, Risk Assessor

Risk Assessment Branch 6

Health Effects Division (7509P)

TO: Lisa Jones/Mary Waller, Risk Management Team 21

Herbicide Branch

Registration Division (7505P)

Risk Management 

The Registration Division (RD) requested that 

exposure and risk assessment for

various crop groups including: Root and Tuber Vegetables (Crop Group 1, except potato, sweet 

potato, and yam bean); Bulb Vegetables (Crop Group 3

vegetables) (Crop Group 4); Brassica (Cole) Leafy Vegetables (Crop Gro

Vegetables (Succulent or Dried) (Crop Group 6); Fruiting Vegetables (Crop Group 8

Cucurbit Vegetables (Crop Group 9); Cereal Grains (Crop Group 15, except rice and wildrice); 

Grass Forage, Fodder, and Hay (Crop Group 17); Non

Straw, and Hay) (Crop Group 18); Herbs and Spices (Crop Group 19); Oilseeds (Crop Group 20, 

except Cotton); Cotton; Ornamental Flowers; and Conifers. 

reviewed by the Exposure Science A

Page 1 of 18

UNITED STATES ENVIRONMENTAL PROTECTION AGENCY

WASHINGTON, D.C. 20460

OFFICE OF CHEMICAL SAFETY

AND POLLUTION PREVENTION

methyl. Occupational and Residential Exposure Assessment for 

Seed Treatment Uses on Various Crop Groups

DP Barcode: D395997

Registration No.:

Regulatory Action: Section 3

Risk Assessment Type: Single Chemical

CAS No.: 57018-04-9

40 CFR: 

Shalu Shelat, Industrial Hygienist 

Branch 6

Health Effects Division (7509P)

Charles Smith, Risk Assessor

isk Assessment Branch 6

Health Effects Division (7509P)

Lisa Jones/Mary Waller, Risk Management Team 21

Herbicide Branch

Registration Division (7505P)

Risk Management Division

The Registration Division (RD) requested that the Health Effects Divison (HED) conduct an 

exposure and risk assessment for a new proposed seed treatment use of tolclofos

various crop groups including: Root and Tuber Vegetables (Crop Group 1, except potato, sweet 

potato, and yam bean); Bulb Vegetables (Crop Group 3-01); Leafy Vegetables (except brassica 

; Brassica (Cole) Leafy Vegetables (Crop Group 5); Legume 

Vegetables (Succulent or Dried) (Crop Group 6); Fruiting Vegetables (Crop Group 8

Cucurbit Vegetables (Crop Group 9); Cereal Grains (Crop Group 15, except rice and wildrice); 

Grass Forage, Fodder, and Hay (Crop Group 17); Non-grass Animal Feeds (Forage, Fodder, 

Straw, and Hay) (Crop Group 18); Herbs and Spices (Crop Group 19); Oilseeds (Crop Group 20, 

except Cotton); Cotton; Ornamental Flowers; and Conifers. Note: This memorandum was 

reviewed by the Exposure Science Advisory Council (ExpoSAC) on 11/10/2011

UNITED STATES ENVIRONMENTAL PROTECTION AGENCY

CHEMICAL SAFETY

AND POLLUTION PREVENTION

Occupational and Residential Exposure Assessment for 

Health Effects Divison (HED) conduct an 

tolclofos-methyl on

various crop groups including: Root and Tuber Vegetables (Crop Group 1, except potato, sweet 

01); Leafy Vegetables (except brassica 

up 5); Legume 

Vegetables (Succulent or Dried) (Crop Group 6); Fruiting Vegetables (Crop Group 8-10); 

Cucurbit Vegetables (Crop Group 9); Cereal Grains (Crop Group 15, except rice and wildrice); 

l Feeds (Forage, Fodder, 

Straw, and Hay) (Crop Group 18); Herbs and Spices (Crop Group 19); Oilseeds (Crop Group 20, 

This memorandum was 

/2011.
Page 2 of 18

1.0 EXECUTIVE SUMMARY

Tolclofos-methyl (O-(2,6-dichloro-4-methylphenyl) O-O-dimethyl phosphorothioate) is a new 

active ingredient which works as a contact fungicide formulated for seed treatment use to 

provide protection against seed-borne fungal pathogens causing seed decay and seedling 

damping-off. RizolexTM Flowable Fungicide contains 42% tolclofos-methyl (4.17 lbs ai per 

gallon) and is proposed to be used on various seed types. 

This document assesses the occupational exposure and risk estimates for the newly proposed

seed treatment uses of tolclofos-methyl. Based on application rate and label information, 

exposure is expected to occur for short- and intermediate-term durations. Chronic exposure is 

not expected for the proposed use patterns. 

Proposed Use Profile

The proposed tolclofos-methyl application rates range from 0.00009773 to 0.000489 lb ai/lb seed 

for seed treatment. Tolclofos-methyl seed treatment uses are to be applied utilizing mechanical, 

slurry, or mist-type seed treating equipment. The product is proposed for both commercial seed 

treatment facilities and on-farm application, but is not allowed to be applied in a hopper-box or 

planter-box at planting time. The proposed label also states that the product is only to be 

applied to “true seeds” and is not to be applied on other propagation parts. 

Residential Exposure

Residential exposures and risk estimates are not assessed in this document because the proposed 

uses of tolclofos-methyl do not involve applications by homeowners or commercial applicators 

in residential settings at this time and there are no existing or proposed residential uses.

Occupational Handlers

Occupational handler exposure is expected for individuals involved in commercial seed 

treatment (primary handlers) and planting treated seeds (secondary handlers). Dermal risk 

estimates were not assessed for this use because systemic toxicity and dermal irritation was not 

observed at concentrations up to the limit dose (1,000 mg/kg/day) after 3 weeks of exposure (5 

days/week for 3 weeks). The inhalation risk estimates do not exceed HED’s LOC (MOE ≥ 100) 

and therefore are not of concern to HED. MOEs for all primary handler seed treatment activities 

ranged from 14,000 to 51,000,000 and MOEs for secondary handler activities planting treated 

seed ranged from 147,000 to 870,000,000.

Occupational Post-Application 

The potential for short- and intermediate-term occupational exposure to tolclofos-methyl during 

post-application activities is unlikely because sustained levels of contact with treated seed is not 

expected after the seed has been placed in the soil or other planting media. Therefore, no 

quantitative post-application assessment is required for exposure to treated seeds that have 

already been planted.

Label Recommendations

The labeling should state: Seed that has been treated with this product that is then packaged or 

bagged for future use must contain the following labeling on the outside of the seed package or 

bag. 
Page 3 of 18

"Treated Seed - Do Not Use for Food, Feed, or Oil Purposes. Store away 

from feeds and other foodstuffs. 

When opening this bag or loading/pouring the treated seed, wear a long-sleeved 

shirt, long pants, shoes, socks, and chemical resistant gloves. After the seeds have 

been planted, do not enter or allow worker entry into treated areas during the 

restricted-entry interval (REI) of 12 hours. Exception: Once the seeds are planted 

in soil or other planting media, the Worker Protection Standard allows workers to 

enter the treated area without restriction if there will be no worker contact with 

the treated seeds in the soil or planting media."

Review of Human Research

This risk assessment relies in part on data from studies in which adult human subjects were 

intentionally exposed to a pesticide or other chemical. These data, which include ExpoSAC 

Policy 14 (SOPs for Seed Treatment), are subject to ethics review pursuant to 40 CFR 26, have 

received that review, and are compliant with applicable ethics requirements. For certain studies 

that review may have included review by the Human Studies Review Board. Descriptions of 

data sources as well as guidance on their use can be found at 

http://www.epa.gov/pesticides/science/handler-exposure-data.html and 

http://www.epa.gov/pesticides/science/post-app-exposure-data.html.

2.0 HAZARD CHARACTERIZATION

Tolclofos-methyl is an organophosphate with several older toxicity studies (dating back to 

1970s) submitted for consideration in risk assessment. Upon re-evaluation of these old toxicity

studies (1970s to 1980s), several studies are now considered unacceptable: 90-day oral rat 

(MRID No. 00156135) (1982); developmental rat (MRID No. 00156142) (1979); developmental 

rabbit (MRID No. 00156143) (1982); 3-generation reproduction (MRID No. 00156145) (1985); 

carcinogenicity mouse (MRID No.00156139) (1983), and chronic/carcinogenicity rat (MRID 

No. 00156140) (1982). 

Based on the re-evaluation of these old toxicity studies, the toxicity database for tolclofos-methyl 

is not complete but adequate for the proposed non-food seed treatment use. Data from the 

following studies were used to evaluate the hazard potential of tolclofos-methyl: 

- Acute lethality studies (oral, dermal, inhalation, primary eye and dermal irritation, dermal 

sensitization)

- Subchronic dietary (rat, dog)

- 9-month dietary (mouse)

- 104-week special Cholinesterase (rat)

- Developmental (rat, 41422904)

- Neurotoxicity (acute and subchronic) (rat)

- Metabolism (rat, mouse)

- Immunotoxicity (rat)

- Mutagenicty battery

Tolclofos-methyl is a new active ingredient although it has been registered in other countries 

(European Union countries) for several years. A search in PubMed (August 2011) with 

tolclofos-methyl as a search term resulted in no applicable toxicity studies for risk assessment 
Page 4 of 18

and no toxicity studies with humans were submitted. Any future uses (other than seed treatment) 

requested by the registrant will require several new toxicity studies to fulfill the Revised Part 158 

guidelines for either a non-food or a food use. 

Tolclofos-methyl has low acute toxicity by oral, dermal, and inhalation routes. It is not a dermal 

sensitizer, or a skin or eye irritant. The acute toxicity profiles of tolclofos-methyl are 

summarized in Table 1.

Table 1. Acute Toxicity Profile for Tolclofos-methyl*

Guideline 

No. Study Type MRID Results Toxicity Category

870.1100

Acute oral- rat

Acute oral-mouse

Acute oral-dog

00156124 (1985)

00156128 (1978)

00156125 (1978)

Combined LD50 > 5 g/kg, rats#

3500 mg/kg (2760-4800), mice

>1000 mg/kg/day

IV

III

III

870.1200 Acute dermalrabbit

00156126 (1985)

Water vehicle

1/5 died by day 5

No clinical signs after dosing of 

surviving rabbits.

LD50 > 2 g/kg

III

870.1300

Acute inhalation –

rat

-rat

41410501 (1986)@

Powder,nonacceptable/non-guideline

41445702 (1983) @

25% flowable, 

unacceptable/nonguideline

LC50≥ 3.32 mg/L

Particles 0.3-5.5μm

%MMAD 1μm or less not met

LC50≥ 0.146 mg/L

MMAD not determined

III

NA

870.2400

Primary eye 

irritation- rabbit 00156129 (1985) Transient slight conjunctival reaction (24 hrs or less). Not an eye irritant IV

870.2500

Primary Dermal 

irritation- rabbit 00156131 (1985) PIS=0, not an irritant IV

870.2600

Skin sensitizationguinea pig 00156131 (1985) Not a contact sensitizer N/A

*Acute summaries found in TXR006933

#Clinical signs (piloerection, hunched posture) in all animals were observed shortly after dosing with complete 

recovery by 5 days post-dosing.

@

Studies found in TXR008856

In risk assessments for non-food uses that do not result in residential exposures, PODs are 

selected for the dermal and inhalation routes of exposure only. In this case, there is no dermal 

toxicity and therefore a dermal POD has not been selected and a quantitative dermal assessment 

not performed. A quantitative assessment was only performed for the inhalation route. PODs for 

the acute and chronic dietary and incidental oral exposures are not required to assess risk for 

non-food uses that do not result in residential exposures, and therefore have not been selected.

Acute and Chronic Dietary

The current proposed use is a non-food seed treatment. Acute and chronic PODs have not been 

established for this risk assessment.

Short/Intermediate Dermal

The 21-day dermal rabbit study (non-guideline) was re-evaluated to ensure consistency with 

current HED policy and practices. Based upon this re-evaluation, systemic toxicity and dermal 
Page 5 of 18

irritation was not observed at concentrations up to the limit dose (1,000 mg/kg/day) after 3 weeks 

of exposure (5 days/week for 3 weeks). Therefore a quantitative short- and intermediate-term 

dermal assessment has not been conducted for tolclofos-methyl.

Short/Intermediate Inhalation

The short- and intermediate-term inhalation POD was based on oral toxicity studies since route 

specific inhalation data are currently unavailable. The 90-day rat and 6- month dog studies 

provide the most appropriate PODs to consider for risk assessment. The 90-day rat and 6-month 

dog studies were selected as co-critical since they yield similar NOAELs and LOAELs for use in 

risk assessment. The NOAEL of 23 mg/kg/day from the 6-month dog study, which is similar to 

the RBC BMDL10 of 34 mg/kg/day from the 90-day rat study, is the most appropriate POD and 

protective of the short-term and intermediate-term durations of exposure. An uncertainty factor 

of 100x (10x to account for interspecies extrapolation and 10x for intraspecies variation) was 

applied to the POD. This POD is considered health protective since the recently submitted ACN 

and SCN studies resulted in no ChE inhibition or toxicity near the limit dose of 1,000 mg/kg/day.

Carcinogenicity and Cancer Classification

There are no currently registered or proposed food uses for tolclofos-methyl. Carcinogenicity 

studies are not required for non-food use chemicals. Carcinogenicity studies in mice and rats are 

available for tolclofos-methyl and both of these studies were deemed unacceptable for use in the 

risk assessment. These cancer studies would be required under the Revised Part 158 Guidelines 

should a food use for tolclofos-methyl be requested in the future.

Uncertainty Factors

Food Quality Protection Act (FQPA) considerations do not apply to tolclofos-methyl as the 

proposed seed treatment uses have been deemed non-food uses. However, there are three 

outstanding studies according to revised 40 CFR Part 158 Toxicology Data Requirements. These 

studies include a development toxicity study in rabbits, a reproduction study in rats, and an 

adequate in vivo mammalian cell assay. The Agency is not requesting any of these studies at this 

time and does not believe a UFDB is required for the lack of these studies. Based on the proposed 

uses, quantification of risk is limited to short- and intermediate-term inhalation exposure for 

workers. The PoD used for assessing repeated inhalation exposure is based on the most sensitive 

endpoint in the most sensitive species (dogs) and supported by the observation of similar effects 

at a comparable dose in the rat. Consequently, the risk assessment does not underestimate 

potential risks to occupational workers and a total uncertainty factor of 100 is adequate.

Table 2.0. Summary of Toxicological Doses and Endpoints for Tolclofos-Methyl for Non-Food Use 

Occupational Risk Assessments

Exposure/

Scenario

Point of 

Departure 

(POD)

Uncertainty 

Factors

Level of 

Concern Study and Toxicological Effects

Acute Dietary (General 

Population, including 

Infants and Children)

The proposed seed treatment use is non-food.

Chronic Dietary (All 

Populations) The proposed seed treatment use is non-food.

Dermal 

(Short/Intermediate) Systemic toxicity was not observed up to the limit dose of 1,000 mg/kg/day.
Page 6 of 18

Table 2.0. Summary of Toxicological Doses and Endpoints for Tolclofos-Methyl for Non-Food Use 

Occupational Risk Assessments

Exposure/

Scenario

Point of 

Departure 

(POD)

Uncertainty 

Factors

Level of 

Concern Study and Toxicological Effects

Inhalation

(Short/Intermediate)

NOAEL= 

23 mg/kg

UFA = 10X

UFH = 10X MOE = 100

Co-Critical:

1. 6-month dog (00156138); 

LOAEL = 70 mg/kg/day, based on

decreased bodyweight and gain, hematocrit, 

hemoglobin, and erythrocyte count in both 

sexes. In addition, ↓relative thyroid weight, 

↑ALK and ↑absolute and relative liver wt at 

high dose.

A consistent dose-response for ChE was not 

observed.

2. 90-day rat (41422901)

RBC BMDL10=34 MKD

RBC BMD10=72 MKD

Cancer (oral, dermal, 

inhalation) Not required for non-food use pesticides.

Point of Departure (POD) = A data point or an estimated point that is derived from observed dose-response data and used to mark the beginning 

of extrapolation to determine risk associated with lower environmentally relevant human exposures. NOAEL = no observed adverse effect level. 

LOAEL = lowest observed adverse effect level. UF = uncertainty factor. UFA = extrapolation from animal to human (interspecies). UFH = 

potential variation in sensitivity among members of the human population (intraspecies).

Food Quality Protection Act (FQPA) considerations do not apply to tolclofos-methyl as the 

proposed seed treatment uses have been deemed non-food uses. However, there are three 

outstanding studies according to revised 40 CFR Part 158 Toxicology Data Requirements. These 

studies include a development toxicity study in rabbits, a reproduction study in rats, and an 

adequate in vivo mammalian cell assay. The Agency is not requesting any of these studies at this 

time and does not believe a UFDB is required for the lack of these studies. Based on the proposed 

uses, quantification of risk is limited to short- and intermediate-term inhalation exposure for 

workers. The PoD used for assessing repeated inhalation exposure is based on the most sensitive 

endpoint in the most sensitive species (dogs) and supported by the observation of similar effects 

at a comparable dose in the rat. Consequently, the risk assessment does not underestimate 

potential risks to occupational workers and a total uncertainty factor of 100 is adequate.

3.0 PROPOSED USE PATTERNS

Tolclofos-methyl is a new active ingredient being proposed for seed treatment use on various 

crops, turf grass, ornamental flower, and conifers. The proposed formulated product is a liquid 

containing 42.0% tolclofos-methyl active ingredient (4.17 lbs tolclofos-methyl per gallon). The 

proposed label is for both commercial and on-farm seed treatment. The proposed label restricts 

the use of tolclofos-methyl in hopper-box or planter-box seed treatment systems at planting time. 

The proposed label also states that the product is only to be applied to “true seeds” and is not to 

be applied on other propagation parts. The application rates range from 0.000489 to 0.00000977 

lb ai/lb seed.

Table 3.0: Use Profile for Proposed Tolclofos-methyl Uses

Rizolex Flowable Fungicide (Reg. No. XXX-XXX)

suspension concentrate (SC), 4.17 lb ai/gallon
Page 7 of 18

Crops Application 

Equipment

Maximum

Application 

Rate

Notes

- Root and Tuber Vegetables (Crop 

Group 1A)

Commercial Seed 

Treatment Facility 

and On-Farm

Standard Slurry or 

Mist-Type

0.000489 lb 

ai/lb seed

except Burdock, Chervil, Turnip-Rooted; 

Ginseng; Horseradish; Salsify; Skirret;

- Cotton

- Bulb Vegetables (Crop Group 3-7)

Commercial Seed 

Treatment Facility 

and On-Farm

Standard Slurry or 

Mist-Type

0.00000977 lb 

ai/lb seed

except Daylily, Bulb; Elegans Hosta; 

Fritillaria, Bulb; Fritillaria, Leaves; 

Garlic, Bulb; Garlic, Great-Headed, 

Bulb; Garlic, Serpent, Bulb; Lily, Bulb; 

Onion, Chinese, Bulb; Onion, 

Macrostem; Onion, Tree, Tops; Onion, 

Welsh, Tops; Shallot, Bulb ; Shallot, 

Fresh Leaves

- Leafy Vegetables (Crop Group 4) except Brassica Vegetables

- Brassica (Cole) Leafy Vegetables 

(Crop Group 5)

- Legume Vegetables (Succulent or 

Dried) (Crop Group 6)

- Fruiting Vegetables (Crop Group 8-

10)

- Cucurbit Vegetables (Crop Group 9)

- Cereal Grains (Crop Group 15) except Rice and Wildrice

- Grass Forage, Fodder, and Hay (Crop 

Group 17)

- Non-grass Animal Feeds (Forage, 

Fodder, Straw, and Hay) (Crop Group 

18)

- Herbs and Spices (Crop Group 19)

- Oilseeds (Crop Group 20) except cotton

- Ornamental Flowers

- Conifers

4.0 RESIDENTIAL (NON-OCCUPATIONAL) EXPOSURE

Residential exposure and risk estimates are not assessed in this document because the proposed 

uses of tolclofos-methyl do not involve applications by homeowners or commercial applicators 

in residential settings at this time and there are no existing or proposed residential uses.

5.0 OCCUPATIONAL EXPOSURE/RISK PATHWAY

Occupational handler exposure to tolclofos-methyl is expected for handlers involved in 

commercial seed treatment and on-farm seed treatment (not for direct use in a hopper-box or 

planter-box). However, with respect to treated seed, exposure from post-application activities is 

unlikely.

5.1 Seed Treatment Occupational Handler

Occupational seed treatment handlers may experience short- and intermediate-term exposure to
Page 8 of 18

tolclofos-methyl while performing seed treatment activities in commercial settings. In addition, 

occupational secondary handlers may experience short- and intermediate-term exposure while 

planting tolclofos-methyl -treated seeds. No chemical-specific handler exposure data were 

submitted in support of this use pattern. For assessing commercial seed treatment and seed 

planting activities, unit exposure data were taken from HED ExpoSAC Policy 14: SOPs for Seed 

Treatment. The amount of active ingredient handled depends on the application rate (lb ai/lb 

seed), the pounds of seed treated in a day, and the pounds of seed that can be planted in a day, all 

of which vary depending upon the seed type. Values for the amount of seed treated and planted 

per day were obtained from HED ExpoSAC Policy 14 and 15 as well as information obtained 

from the Biological and Economic Analysis Division (BEAD) memo entitled, “Acres Planted 

per Day and Seeding Rates of Crops Grown in the United States” (J. Becker and S. Ratnayake; 

3/24/11). 

Treating Seed (Primary Handler)

Potential occupational exposure scenarios from the use of tolclofos-methyl as a commercial seed 

treatment include:

 Mixing, loading, applying liquid formulations;

 Bagging treated seed;

 Sewing bags; and

 Multiple activities.

Typically, for large-scale commercial seed treatments, workers perform only those specific 

individual tasks listed above; however, it is assumed that workers also may perform multiple 

activities throughout the day. As a result a “multiple activities” scenario (i.e. where one worker 

performs all seed treatment tasks such as loading/applying, sewing, bagging, cleaning, 

calibration, repair, forklift driver, etc.) was addressed.

Planting Treated Seed (Secondary Handler)

Potential occupational exposure scenarios from the use of tolclofos-methyl as a commercial seed 

treatment include planting treated seed (secondary handler).

Planting treated seed consists of the farmer purchasing bags of treated seed, placing the seed in 

the hopper and applying seed to fields (considered a secondary handler exposure scenario).

5.3.1 Exposure Data, Factors, and Assumptions

The following are exposure factors and assumptions used to calculate exposure and risk

estimates in the occupational assessment for commercial seed treatment scenarios. 

Unit Exposures

Chemical-specific data for assessing exposure during commercial seed treatment and seed 

planting were not submitted to the Agency in support of this Section 3 application. Unit 

exposures are from ExpoSAC Policy 14: SOPs for Seed Treatment (May 1, 2003). Unit 
Page 9 of 18

exposure values from ExpoSAC Policy 14 are based on data for open mixing/loading/application 

systems. 

Amount of Seed Treated Per Day (Primary Handler)

HED is currently in the process of revising ExpoSAC Policy 15: Amount of Seed Treated or 

Planted per Day (March 2, 2004) in efforts to update the daily amount of seed treated in 

commercial seed treatment facilities. With the increasing demand for hybridized treated seeds, 

there have been modifications not only in the seed treatment equipment, but in the market shares 

of new and currently registered pesticide products. HED understands that due to the high cost of 

producing hybrid seeds, direct seeding is done in a precision manner which requires lower 

volumes of seed per acre. However, this does not provide a direct correlation to the amount of 

seed which is treated in the commercial seed treatment facilities. 

The amount of seed treated per day at a commercial facility is summarized below for each crop. 

 Root and Tuber Vegetables (Crop Group 1, except potato, sweet potato, and yam bean)- 5,500 lbs

 Bulb Vegetables (Crop Group 3-01)- 5,500 lbs

 Leafy Vegetables (except brassica vegetables) (Crop Group 4) - 5,500 lbs

 Brassica (Cole) Leafy Vegetables (Crop Group 5) - 5,500 lbs

 Legume Vegetables (Succulent or Dried) (Crop Group 6) - 5,500 lbs

 Fruiting Vegetables (Crop Group 8-10) - 5,500 lbs

 Cucurbit Vegetables (Crop Group 9) - 5,500 lbs

 Cereal Grains (Crop Group 15, except rice and wildrice) - 718,000 lbs

 Grass Forage, Fodder, and Hay (Crop Group 17) - 718,000 lbs

 Non-grass Animal Feeds (Forage, Fodder, Straw, and Hay) (Crop Group 18) - 718,000 lbs

 Herbs and Spices (Crop Group 19) - 5,500 lbs

 Oilseeds (Crop Group 20, except Cotton) - 718,000 lbs

 Cotton – 160,000 lbs

 Ornamental Flowers - 5,500 lbs

 Conifers – 2,000 lbs

Amount of Seed Planted Per Day (Secondary Handler)

Based on ExpoSAC Policy 15: Amount of Seed Treated or Planted per Day, the amount of seed 

planted per day is summarized below for each crop. The amount of seed planted per day

incorporates the information available from the BEAD memo entitled, “Acres Planted per Day 

and Seeding Rates of Crops Grown in the United States” (J. Becker and S. Ratnayake; 3/24/11). 

The amount of seed planted per day for ornamental seeds was obtained by researching various 

ornamental and grower websites1to obtain a seeding rate for the flower types identified by the 

registrant (i.e., zinnias, marigolds, lupine, dianthus, cyclamen, and verbenias). Typical seeding 

rates for these types of flowers appear to range from less than 1 lb of seed per acre to 11 lbs of 

seed per acre. To be protective of the various seed types, HED assumes that up to 11 lbs of 

ornamental flower seed can be planted per acre (or 440 lbs of seed planted per day). 

 

1

http://www.on.ec.gc.ca/wildlife/docs/doc-planting-prairie-e.html#plantingtheprojectsite; 

http://www.baileyseed.com/wildflowersmixes.asp; http://www.mowildflowers.net/growinginfo/wildmixes.html
Page 10 of 18

 Root and Tuber Vegetables (Crop Group 1, except potato, sweet potato, and yam bean)- 2,614 lbs

 Bulb Vegetables (Crop Group 3-01)- 1,004 lbs

 Leafy Vegetables (except brassica vegetables) (Crop Group 4) - 697 lbs

 Brassica (Cole) Leafy Vegetables (Crop Group 5) - 211 lbs

 Legume Vegetables (Succulent or Dried) (Crop Group 6) – 32,920 lbs

 Fruiting Vegetables (Crop Group 8-10) - 209 lbs

 Cucurbit Vegetables (Crop Group 9) – 726 lbs

 Cereal Grains (Crop Group 15, except rice and wildrice) - 37,500 lbs

 Grass Forage, Fodder, and Hay (Crop Group 17) – 2,800 lbs

 Non-grass Animal Feeds (Forage, Fodder, Straw, and Hay) (Crop Group 18) – 12,800 lbs

 Herbs and Spices (Crop Group 19) - 836 lbs

 Oilseeds (Crop Group 20, except Cotton) - 2,800 lbs

 Cotton – 2,667 lbs

 Ornamental Flowers - 440 lbs

 Conifers – 2,000 lbs

Application Rates

The proposed treatment range is 0.00000977 to 0.000489 lb ai/lb seed for seed treatment. The 

maximum application rates are shown above in Table 3. 

Body Weight

The average adult weight of 80 kg was used for estimating inhalation exposure. No dermal point 

of departure was selected, therefore a short- and intermediate-term dermal assessment is not 

being conducted for tolclofos-methyl.

Exposure Duration

It is anticipated that occupational tolclofos-methyl exposures will generally occur in short- (1-30 

days) and intermediate- (1-6 months) term durations.

Absorption Factor

Since no inhalation absorption data are available, toxicity by the inhalation route is considered to 

be equivalent to the estimated toxicity by the oral route of exposure (100% absorption factor).

Equations and Calculations

Daily Exposure

Daily handler exposures are estimated for each applicable handler task with the application rate, 

the amount of seed treated or seed planted in a day, and the applicable unit exposure using the 

following formula:

Daily Exposure (mg ai/day) = Unit Exposure (mg ai/lb ai handled) * Application Rate (lbs ai/lb seed) * 

Daily Amount Handled (lbs seed/day)

Where: 
Page 11 of 18

Daily Exposure = Amount (mg ai/day) deposited on the surface of the skin that is available for 

dermal absorption or amount inhaled that is available for inhalation 

absorption,

Unit Exposure = Unit exposure value (mg ai/day),

Application Rate = Normalized application rate based on a logical unit treatment, such as 

pounds seed or acres; maximum values are used (lb ai/lb seed), and

Daily Amount Handled = Amount seed treated per day (lb seed/day) or amount seed planted per day 

(lb seed/day).

Daily Dose

Daily dose (dermal or inhalation) was calculated by normalizing the daily dermal or inhalation 

exposure value by body weight and accounting for dermal and inhalation absorption. 

Average Daily Dose (mg/kg/day) = Daily Exposure (mg ai/day) x {Absorption Factor (%/100)}

Body Weight (kg)

Where:

Average Daily Dose = Absorbed dose received from exposure to a pesticide in a given scenario 

(mg pesticide active ingredient/kg body weight/day),

Daily Exposure = Amount (mg ai/day) deposited on the surface of the skin that is available for 

dermal absorption or amount inhaled that is available for inhalation 

absorption,

Absorption Factor = A measure of the amount of chemical that crosses a biological boundary 

such as the lungs, and

Body Weight = Body weight determined to represent the population of interest in a risk

assessment.

Margin of Exposure (MOE)

The daily inhalation doses received by occupational handlers were compared to the appropriate 

points of departure (i.e. NOAELs) to assess the risk estimates to occupational handlers for each 

exposure route. All MOEs were calculated using the following formula:

MOE = NOAEL (mg/kg/day)

Average Daily Dose (mg/kg/day)

Where:

MOE = Margin of exposure value used by HED to represent risk or how close a chemical 

exposure is to being a concern (unitless),

ADD = Average daily dose (ADD) is absorbed dose received from exposure to pesticide, and

NOAEL = Dose level in a toxicity study, where no observed adverse effects occurred in the study.

5.3.2 Seed Treatment Handler Exposure and Risk Estimates Summary 

Primary Handler

A summary of the inhalation risk estimates for each seed treatment exposure scenario is 

presented in Table 5 for short-term and intermediate-term inhalation exposures. 

The results of the occupational handler exposure and risk assessment indicate that inhalation risk

estimates are not of concern (MOEs ≥ 100) at baseline attire (i.e., long-sleeved shirt, long pants, 

shoes and socks) and no respirator. 

HED is currently in the process of revising ExpoSAC Policy 15 in efforts to update the daily 
Page 12 of 18

amount of seed treated in commercial seed treatment facilities. With the increasing demand for 

hybridized treated seeds, there have been modifications not only in the seed treatment 

equipment, but in the market shares of new and currently registered pesticide products. HED 

understands that due to the high cost of producing hybrid seeds, direct seeding is done in a 

precision manner which requires lower volumes of seed per acre. However, this does not 

provide a direct correlation to the amount of seed which is treated in the commercial seed 

treatment facilities. Over the past several years, HED has received submissions from Industry for 

the use of several seed treatment pesticides which provide a range of daily amounts of vegetable 

seeds treated (1,000 to 5,500 lbs). The amount chosen for many of the fruit, vegetable, and 

ornamental crop groups (5,500 lbs) is conservative. For Crop Groups 15, 17, 18, and 20 the 

standard assumption of 718,000 lbs of seed treated is appropriate, as is the 160,000 lbs 

assumption for cotton. 

Based on an email submitted by Scott Enebak, director of the Forest Health Dynamics 

Laboratory at Auburn University, an average nursery produces 30,000,000 seedlings per year. 

As such, 400-500 pounds of nursery tree seeds are treated per day for five days in the spring time 

during the treating season (enough to sow 30,000,000 seedlings). Nursery tree seeds can range 

anywhere from 4,900 seeds/lb to 75,000 seeds/lb, with the majority of seeds falling in the range 

from 12,000 seeds/lb to 15,000 seeds/lb. Table 4 shows the variation in the range of pine species 

seed sizes. To be protective of the variations in seed size, HED assumes that up to 10,000,000 

seeds can be treated per day (or 2,000 lbs, calculated from the most protective value of 4,900 

seeds/lb). This value will be used to represent the treatment of conifer seeds. 

Table 4. Amount of Seed Needed to Direct Seed an Acre and the Approximate Number of Seeds/Lb.

Pine Species Pounds of Seed Needed Per Acre Approximate Number of Seeds Per Pound

Loblolly 0.5 18,200

Slash 0.6 13,500

Longleaf 2.5 4,900

Sand 0.6 75,000

a Data from Forest Regeneration Methods: Natural Regeneration, Direct Seeding and Planting, M. L. Duryea, University of 

Florida Extension, Institute of Food and Agricultural Sciences, Circular 759, March 1992.

Secondary Handler

Table 6 shows that the planter (secondary handler) short- and intermediate-term inhalation

exposure risk estimates result in MOEs ranging from 160,000 to 24,000,000. These risk

estimates do not exceed HED’s level of concern (MOE ≥ 100) at some level of risk mitigation 

(i.e., gloves, no respirator) for handlers planting treated seed.

Nursery tree seedling planting is predominantly mechanized, and thus secondary handler 

exposure to planting treated nursery seeds is expected to be very low. Pine seeds are planted 

with seed drills that are capable of drilling several million seeds per day, averaging 6,000,000

seeds per day for medium sized nurseries of average production, equating to an average of 10 

acres of seed sown per day (e-mail correspondence with Scott Enebak, Director of Forest Health 

Dynamics Laboratory, Auburn University). To be protective of the variations in seed size, HED 

assumes that up to 10,000,000 seeds can be planted per day in a larger nursery (or 2,000 lbs, 
Page 13 of 18

calculated from the most protective value of 4,900 seeds/lb). This assumption was determined to 

be appropriate for conifer seeds as well. 

On-Farm Seed Treatment

On-farm seed treatment utilizes similar machinery as commercial seed treatment; the only

difference being the size of the equipment. With the specific label restricting direct product use 

in hopper-boxes and planter-boxes, the assessed commercial seed treatment exposure and risk

estimates are protective of on-farm seed treatment scenarios.

5.4 Seed Treatment Occupational Post-Application Exposures and Risk Estimates 

A post-application inhalation exposure assessment is not required as exposure is expected to be 

negligible. Seed treatment assessments provide quantitative inhalation exposure assessments for 

seed treaters and secondary handlers (i.e.planters). It is expected that these exposure estimates 

would be protective of most post-application inhalation exposure scenarios.

The potential for post-application exposures following the planting of tolclofos-methyl-treated 

seeds is unlikely. Sustained levels of contact with treated seed after it has been placed in the soil 

or other planting media would not be expected because no routine cultural practice required for 

the production of agricultural commodities involves such an activity as defined in the no/low 

contact criteria in the Worker Protection Standard (WPS). As a result, no quantitative postapplication assessment is required for exposure to treated seeds that have already been planted.

The labeling should state: Seed that has been treated with this product that is then packaged or 

bagged for future use must contain the following labeling on the outside of the seed package or 

bag. 

"Treated Seed - Do Not Use for Food, Feed, or Oil Purposes. Store away 

from feeds and other foodstuffs. 

When opening this bag or loading/pouring the treated seed, wear a long-sleeved 

shirt, long pants, shoes, socks, and chemical resistant gloves. After the seeds have 

been planted, do not enter or allow worker entry into treated areas during the 

restricted-entry interval (REI) of 12 hours. Exception: Once the seeds are planted 

in soil or other planting media, the Worker Protection Standard allows workers to 

enter the treated area without restriction if there will be no worker contact with 

the treated seeds in the soil or planting media."
Page 14 of 18

Table 5. Summary of Short- and Intermediate-Term Handler Exposures and Risk Estimates for Tolclofos-methyl

Seed Type Inhal UEa Max App Rateb Amt Treatedc

Inhal Dosed

Inhal MOEe

mg/lb lb ai/lb seed lb seed/day mg/kg/day LOC = 100

LOADER/APPLICATOR (single layer, gloves)

Root and Tuber Vegetables (Crop Group 

1, except potato, sweet potato, and yam 

bean)

0.00034 0.000489 5,500 1.14E-05 2,000,000

Bulb Vegetables (Crop Group 3-01) 0.00034 0.00009773 5,500 2.28E-06 10,000,000

Leafy Vegetables (except brassica 

vegetables) (Crop Group 4)

0.00034 0.00009773 5,500 2.28E-06 10,000,000

Brassica (Cole) Leafy Vegetables (Crop 

Group 5) 0.00034 0.00009773 5,500 2.28E-06 10,000,000

Legume Vegetables (Succulent or Dried) 

(Crop Group 6) 0.00034 0.00009773 5,500 2.28E-06 10,000,000

Fruiting Vegetables (Crop Group 8-10) 0.00034 0.00009773 5,500 2.28E-06 10,000,000

Cucurbit Vegetables (Crop Group 9) 0.00034 0.00009773 5,500 2.28E-06 10,000,000

Cereal Grains (Crop Group 15, except 

rice and wildrice) 0.00034 0.00009773 718,000 2.98E-04 77,000

Grass Forage, Fodder, and Hay (Crop 

Group 17) 0.00034 0.00009773 718,000 2.98E-04 77,000

Non-grass Animal Feeds (Forage, 

Fodder, Straw, and Hay) (Crop Group 

18)

0.00034 0.00009773 718,000 2.98E-04 77,000

Herbs and Spices (Crop Group 19) 0.00034 0.00009773 5,500 2.28E-06 10,000,000

Oilseeds (Crop Group 20, except 

Cotton) 0.00034 0.00009773 718,000 2.98E-04 77,000

Cotton 0.00034 0.000489 160,000 3.33E-04 69,000

Ornamental Flowers 0.00034 0.00009773 5,500 6.65E-05 350,000

Conifers 0.00034 0.00009773 2,000 8.31E-07 28,000,000

SEWER (single layer, NO gloves)

Root and Tuber Vegetables (Crop Group 

1, except potato, sweet potato, and yam 

bean)

0.00023 0.000489 5,500 7.73E-06 3,000,000

Bulb Vegetables (Crop Group 3-01) 0.00023 0.00009773 5,500 1.55E-06 15,000,000

Leafy Vegetables (except brassica 

vegetables) (Crop Group 4)

0.00023 0.00009773 5,500 1.55E-06 15,000,000

Brassica (Cole) Leafy Vegetables (Crop 0.00023 0.00009773 5,500 1.55E-06 15,000,000
Page 15 of 18

Table 5. Summary of Short- and Intermediate-Term Handler Exposures and Risk Estimates for Tolclofos-methyl

Seed Type Inhal UEa Max App Rateb Amt Treatedc

Inhal Dosed

Inhal MOEe

mg/lb lb ai/lb seed lb seed/day mg/kg/day LOC = 100

Group 5)

Legume Vegetables (Succulent or Dried) 

(Crop Group 6) 0.00023 0.00009773 5,500 1.55E-06 15,000,000

Fruiting Vegetables (Crop Group 8-10) 0.00023 0.00009773 5,500 1.55E-06 15,000,000

Cucurbit Vegetables (Crop Group 9) 0.00023 0.00009773 5,500 1.55E-06 15,000,000

Cereal Grains (Crop Group 15, except 

rice and wildrice) 0.00023 0.00009773 718,000 2.02E-04 110,000

Grass Forage, Fodder, and Hay (Crop 

Group 17) 0.00023 0.00009773 718,000 2.02E-04 110,000

Non-grass Animal Feeds (Forage, 

Fodder, Straw, and Hay) (Crop Group 

18)

0.00023 0.00009773 718,000 2.02E-04 110,000

Herbs and Spices (Crop Group 19) 0.00023 0.00009773 5,500 1.55E-06 15,000,000

Oilseeds (Crop Group 20, except 

Cotton) 0.00023 0.00009773 718,000 2.02E-04 110,000

Cotton 0.00023 0.000489 160,000 2.25E-04 100,000

Ornamental Flowers 0.00023 0.00009773 5,500 4.50E-05 510,000

Conifers 0.00023 0.00009773 2,000 5.62E-07 41,000,000

BAGGER (single layer, NO gloves)

Root and Tuber Vegetables (Crop Group 

1, except potato, sweet potato, and yam 

bean)

0.00016 0.000489 5,500 5.38E-06 4,300,000

Bulb Vegetables (Crop Group 3-01) 0.00016 0.00009773 5,500 1.08E-06 21,000,000

Leafy Vegetables (except brassica 

vegetables) (Crop Group 4)

0.00016 0.00009773 5,500 1.08E-06 21,000,000

Brassica (Cole) Leafy Vegetables (Crop 

Group 5) 0.00016 0.00009773 5,500 1.08E-06 21,000,000

Legume Vegetables (Succulent or Dried) 

(Crop Group 6) 0.00016 0.00009773 5,500 1.08E-06 21,000,000

Fruiting Vegetables (Crop Group 8-10) 0.00016 0.00009773 5,500 1.08E-06 21,000,000

Cucurbit Vegetables (Crop Group 9) 0.00016 0.00009773 5,500 1.08E-06 21,000,000

Cereal Grains (Crop Group 15, except 

rice and wildrice) 0.00016 0.00009773 718,000 1.40E-04 160,000

Grass Forage, Fodder, and Hay (Crop 0.00016 0.00009773 718,000 1.40E-04 160,000
Page 16 of 18

Table 5. Summary of Short- and Intermediate-Term Handler Exposures and Risk Estimates for Tolclofos-methyl

Seed Type Inhal UEa Max App Rateb Amt Treatedc

Inhal Dosed

Inhal MOEe

mg/lb lb ai/lb seed lb seed/day mg/kg/day LOC = 100

Group 17)

Non-grass Animal Feeds (Forage, 

Fodder, Straw, and Hay) (Crop Group 

18)

0.00016 0.00009773 718,000 1.40E-04 160,000

Herbs and Spices (Crop Group 19) 0.00016 0.00009773 5,500 1.08E-06 21,000,000

Oilseeds (Crop Group 20, except 

Cotton) 0.00016 0.00009773 718,000 1.40E-04 160,000

Cotton 0.00016 0.000489 160,000 1.56E-04 150,000

Ornamental Flowers 0.00016 0.00009773 5,500 3.13E-05 740,000

Conifers 0.00016 0.00009773 2,000 3.91E-07 59,000,000

MULTIPLE ACTIVITIES (combination of loader/applicator with gloves + no coveralls, sewer without gloves, stacker without gloves)

Root and Tuber Vegetables (Crop Group

1, except potato, sweet potato, and yam 

bean)

0.0016 0.000489 5,500 5.38E-05 430,000

Bulb Vegetables (Crop Group 3-01) 0.0016 0.00009773 5,500 1.08E-05 2,100,000

Leafy Vegetables (except brassica 

vegetables) (Crop Group 4)

0.0016 0.00009773 5,500 1.08E-05 2,100,000

Brassica (Cole) Leafy Vegetables (Crop 

Group 5) 0.0016 0.00009773 5,500 1.08E-05 2,100,000

Legume Vegetables (Succulent or Dried) 

(Crop Group 6) 0.0016 0.00009773 5,500 1.08E-05 2,100,000

Fruiting Vegetables (Crop Group 8-10) 0.0016 0.00009773 5,500 1.08E-05 2,100,000

Cucurbit Vegetables (Crop Group 9) 0.0016 0.00009773 5,500 1.08E-05 2,100,000

Cereal Grains (Crop Group 15, except 

rice and wildrice) 0.0016 0.00009773 718,000 1.40E-03 16,000

Grass Forage, Fodder, and Hay (Crop 

Group 17) 0.0016 0.00009773 718,000 1.40E-03 16,000

Non-grass Animal Feeds (Forage, 

Fodder, Straw, and Hay) (Crop Group 

18)

0.0016 0.00009773 718,000 1.40E-03 16,000

Herbs and Spices (Crop Group 19) 0.0016 0.00009773 5,500 1.08E-05 2,100,000

Oilseeds (Crop Group 20, except 

Cotton) 0.0016 0.00009773 718,000 1.40E-03 16,000

Cotton 0.0016 0.000489 160,000 1.56E-03 15,000
Page 17 of 18

Table 5. Summary of Short- and Intermediate-Term Handler Exposures and Risk Estimates for Tolclofos-methyl

Seed Type Inhal UEa Max App Rateb Amt Treatedc

Inhal Dosed

Inhal MOEe

mg/lb lb ai/lb seed lb seed/day mg/kg/day LOC = 100

Ornamental Flowers 0.0016 0.00009773 5,500 3.13E-04 74,000

Conifers 0.0016 0.00009773 2,000 3.91E-06 5,900,000

a Unit Exposures from HED Exposure Science Advisory Council Policy 14 (baseline inhalation = no respirator).

b Application Rates based on proposed label uses for tolclofos-methyl.

c HED default for lb seed treated per day from HED Exposure Science Advisory Council Policy 15.

d Daily Inhalation Dose (mg/kg/day) = daily inhalation unit exposure (mg/lb ai) x application rate (lb ai/lb seed) x amount treated (lb seed/day) x absorption factor (100%) / body weight (80 kg adult).

e Inhalation MOE = NOAEL (23.0 mg/kg/day for short- and intermediate-term exposure) / Inhalation Dose (mg/kg/day). Level of concern = 100.

Table 6. Summary of Secondary Handler (Planter) Exposures and Risk Estimates for Tolclofos-methyl (Single Layer, Gloves for Loading Only).

Seed Type Represented 

by

Max lbs of 

seed/acrea

Inhal 

UEb

Max App 

Ratec

Amt of Seed 

Planted/Dayd

Inhalation

Dosee Inhalation MOEf

lb seed/acre mg/lb lb ai/lb seed lb seed/day mg/kg/day LOC = 100

Root and Tuber Vegetables (Crop 

Group 1, except potato, sweet potato, 

and yam bean)

radish 33 3.4 0.000489 2,614 5.43E-05 420,000

Bulb Vegetables (Crop Group 3-01) onion seed 13 3.4 0.00009773 1,004 4.17E-06 5,500,000

Leafy Vegetables (except brassica 

vegetables) (Crop Group 4)

spinach 9 3.4 0.00009773 697 2.89E-06 8,000,000

Brassica (Cole) Leafy Vegetables 

(Crop Group 5) broccoli 3 3.4 0.00009773 211 8.76E-07 26,000,00

Legume Vegetables (Succulent or 

Dried) (Crop Group 6) pea, garden 412 3.4 0.00009773 32,920 1.37E-04 170,000

Fruiting Vegetables (Crop Group 8-

10) bell pepper 3 3.4 0.00009773 209 8.68E-07 26,000,000

Cucurbit Vegetables (Crop Group 9) watermelon 9 3.4 0.00009773 726 3.02E-06 7,600,000

Cereal Grains (Crop Group 15, except 

rice and wildrice)

wheat (table 

7) 188 3.4 0.00009773 37,500 1.56E-04 150,000

Grass Forage, Fodder, and Hay (Crop 

Group 17)

bluegrass, 

kentucky 35 3.4 0.00009773 2,800 1.16E-05 2,000,000

Non-grass Animal Feeds (Forage, 

Fodder, Straw, and Hay) (Crop Group 

18)

lupin 160 3.4 0.00009773 12,800 5.32E-05 430,000

Herbs and Spices (Crop Group 19) parsely 10 3.4 0.00009773 836 3.47E-06 6,600,000

Oilseeds (Crop Group 20, except 

Cotton) safflower 35 3.4 0.00009773 2,800 1.16E-05 2,000,000

Cotton cotton 13 3.4 0.000489 2,667 5.54E-05 420,000
Page 18 of 18

Table 6. Summary of Secondary Handler (Planter) Exposures and Risk Estimates for Tolclofos-methyl (Single Layer, Gloves for Loading Only).

Seed Type Represented 

by

Max lbs of 

seed/acrea

Inhal 

UEb

Max App 

Ratec

Amt of Seed 

Planted/Dayd

Inhalation

Dosee Inhalation MOEf

lb seed/acre mg/lb lb ai/lb seed lb seed/day mg/kg/day LOC = 100

Ornamental Flowers flowersvaried 11 3.4 0.00009773 440 1.83E-06 12,600,000

Conifers dust 10 3.4 0.00009773 2,000 8.31E-06 2,770,000

a Information from “Acres Planted per Day and Seeding Rates of Crops Grown in the United States” (J. Becker and S. Ratnayake; 3/24/11).: Number of seeds per acre (Table 10) ÷ Number of seeds 

per lb (Table B-1) = Max lbs of seed per acre

b Unit Exposures from HED Exposure Science Advisory Council Policy 14: Standard Operating Procedures for Seed Treatment (baseline inhalation = no respirator).

c Application Rates based on proposed label uses for tolclofos-methyl.

d Incorporation of acres treated per day from HED Exposure Science Advisory Council Policy 15 and “Acres Planted per Day and Seeding Rates of Crops Grown in the United States” (J. Becker and 

S. Ratnayake; 3/24/11): Max lbs of seed per acre x acres planted per day (Policy 15 Table 3)

e Daily Inhalation Dose (mg/kg/day) = daily inhalation unit exposure (mg/lb ai) x application rate (lb ai/lb seed) x amount planted (lb seed/day) x absorption factor (100%) / body weight (80 kg adult).

f Inhalation MOE = NOAEL (23 mg/kg/day for short- and intermediate-term exposure) / Inhalation Dose (mg/kg/day). Level of concern = 100.