UNITED STATES ENVIRONMENTAL PROTECTION AGENCY 

WASHINGTON, D.C. 20460 

OFFICE OF 

CHEMICAL SAFETY ANO 

POLLUTION PREVENTION 

MEMORANDUM 

Date: April 5, 2012 

SUBJECT: Fluridone: ID # I2ARD 1 Section 18 Emergency Exemption for Use on 

Cotton in Arkansas, South Carolina, Tennessee, and Florida. 

PC Codes: 112900 

Decision No.: 462422 

Petition No.: NA 

DP Barcode: 399892 

Registration No.: None 

Regulatory Action: Section 18 

Registration 

Risk Assessment Type: NA 

TXRNo.:NA 

Case No.: NA 

CAS No.: 59756·60-4 

MRID No.: NA 40 CFR: 180.420 

FROM: 

THROUGH: 

TO: 

Danette 

Matthew 

Drew. 

Lloyd 

Chemist! 

(CIH), Industrial 

Risk Assess Hygienist ~ ~ ~~M 

William Irwin, Ph.D., Toxicologist ) .? r-i;> 

Risk 

Health 

Assessment 

Effects Division 

Branch 

(7509P) 

VNII (j)~ ~ 

Michael S. Metzger. Branch Chie /c~/Jf'j rf~ Risk Assessment Branch V NIl M lA-' 

Health Effects Division (7509P) 

Keri Grinstead / Marcel Howard 

Registration Division (7505P) 

Executive Summary 

The Arkansas State Plant Board has requested a Section 18 Specific Exemption for the 

use of fluridone on cotton in Arkansas, South Carolina, Tennessee, and Florida. This 

Page 1 of 10 
Page 2 of 10

Section 18 would allow application of fluridone, as the end-use product Brake®(EPA 

Registration No. 67690-54), to control Palmer amaranth during the 2012 cotton growing 

season. This is the first Section 18 request for this use. 

EPA’s Health Effects Division (HED) has examined the Section 18 request materials and 

available data and has determined that the proposed use of fluridone on cotton, and on 

turnrows and ditchbanks adjacent to cotton fields, is supported by recent fluridone human 

health risk assessments, primarily those prepared for the 2004 Tolerance Reassessment 

Progress and Risk Management Decision (TRED). The dietary (food, water), residential, 

and aggregate risk estimates determined in the most recent risk assessments remain 

unchanged and are below HED’s level of concern. The occupational exposure scenarios 

assessed in conjunction with this Section 18 proposed use on cotton indicate that 

occupational handler exposures will not exceed HED’s level of concern with baseline 

clothing. The WPS reentry interval of 12 hours listed on the original label is adequate for 

the proposed use.

HED concludes that the application of Brake®(fluridone) to control Palmer amaranth in 

cotton would not result in occupational, dietary (food or water), residential, or aggregate 

(dietary plus residential) exposures or risk estimates of concern provided the Section 18 

supplemental label (EPA Reg. No. 67690-54) is modified to specify the maximum 

seasonal rate allowed [do not apply more than 1.56 gallons of Brake per acre (0.5 pounds 

active ingredient fluridone/acre) per year]. 

For the purposes of this Section 18 request only, the cited residue data may be used to 

conclude that the residues of fluridone on cotton would not be expected to exceed the 

current tolerance 0.1 ppm (cotton, undelinted seed) when fluridone is applied preplant or 

preemergent to cotton field soil, or to turnrows and ditchbanks adjacent to cotton fields, 

at a maximum seasonal rate of 0.5 lb ai/A.

Codex maximum residue limits (MRLs), Mexican MRLs, and Canadian MRLs have not 

been established for fluridone residues, so there are no concerns for international 

harmonization with U.S. tolerances.

General Use Information

Fluridone (1-methyl-3-phenyl-5-[3-trifluoromethyl)phenyl]-4(1 H)-5-[3-

(trifluoromethyl)phenyl]-4(1 H )-pyridinone) is an aquatic herbicide used on ponds 

(including a homeowner use), lakes, reservoirs, irrigation canals, drainage canals, and 

rivers. Fluridone may also be used in dry canals.

The currently registered uses of fluridone may result in dietary exposures from food from 

irrigated crops and from drinking water. Residential uses of fluridone can result in 

dermal and inhalation exposure. People may also be exposed when swimming in treated 

water, resulting in dermal, ingestion, aural, buccal/sublingual, and nasal/orbital exposure. 

Occupational uses may result in exposures via the dermal and inhalation routes.
Page 3 of 10

The proposed Section 18 use pattern is as follows: 

The end-use product, Brake®, is a soluble concentrate containing 3.79% fluridone (0.32 

lb ai/gallon). One broadcast or band application at a maximum seasonal rate of 0.5 lb 

ai/A is proposed for cotton fields and for turnrows and ditchbanks adjacent to cotton 

fields. Brake® may be applied as a preplant soil incorporated or preemergence surface 

application to cotton fields. Applications to turnrows and ditchbanks should be made 

prior to Palmer amaranth emergence or tankmixed with an herbicide labeled for removal 

of existing weeds. Chemigation is prohibited. There are no aerial applications as the 

label directions clearly direct the user to ground-based application equipment. The use 

period is from April to June 2012 for cotton fields and from March 1 to August 1, 2012 

for turnrows and ditchbanks. The exemption expiration would be August 1, 2012.

The Section 18 supplemental Brake®label, EPA Reg. No. 67690-54, does not specify a 

maximum seasonal (or annual) rate and states “do not make more than two consecutive 

applications”. The parent label, 67690-48, does specify “do not apply more than 1.56 

gallons of Brake per acre (0.5 pounds fluridone/acre) per year”. The supplemental label 

should specify the maximum annual rate allowed.

Hazard Identification and Toxicology

Fluridone has low to moderate acute oral, inhalation and dermal toxicity. Fluridone is 

not irritating to skin, nor is it a skin sensitizer, but is a moderate irritant to the eyes. The 

liver and kidneys were the target organs in rats following sub-chronic dietary exposures. 

Following sub-chronic exposure to dogs, no systemic toxicity was observed. Fluridone 

caused hepatotoxicity, characterized as alterations in a liver enzyme and increased liver 

weight, in chronic dog studies. The target organs for fluridone-induced toxicity were the 

liver, kidneys, and testes, revealed in chronic toxicity/carcinogenicity studies. Toxicity 

in mice was limited to the liver and manifested as changes in a liver enzyme and 

histopathology, observed in a carcinogenicity study. Based on the lack of evidence for 

carcinogenicity in these studies (mice and rats), fluridone is classified as Group E 

Carcinogen -Evidence of Non-Carcinogenicity for Humans. There is no evidence that 

fluridone has the potential to be toxic to either the nervous or the immune system. There 

is no evidence of increases susceptibility following in utero exposures to rats and rabbits 

or following pre-and post-natal exposures to rats for two generations.

Toxicological points of departure (PODs) were selected for acute and chronic oral 

exposures. PODs were also selected for short-term and intermediate-term oral, dermal, 

and inhalation exposures. The 10X FQPA Safety Factor was reduced to 1X since the 

toxicology data base is substantially complete, there are no residual uncertainties for preand/or post-natal toxicity, and dietary and residential exposures are not likely to be 

underestimated.

The hazard identification and toxicology for fluridone is based on the recent human 

health risk assessment scoping document completed in 2009 (D361849). Summary tables 
Page 4 of 10

of the most recent toxicological PODs and uncertainty factors can be found in Appendix 

1.

Residue Chemistry and Tolerance

Fluridone is currently not registered for direct application to crops, but crops may be 

irrigated with treated water. Tolerances are established for fish, crayfish and animal 

commodities. Tolerances are also established for indirect or inadvertent residues of 

fluridone on several crops as a result of irrigation with treated water. The current 

tolerance for residues of fluridone on cotton, undelinted seed is 0.1 ppm and is listed in 

40CFR 180.420 (c) under the following definition:

180.420(c) Tolerances are established in the following irrigated crops and crop 

groupings for residues of the herbicide fluridone, including its metabolites and 

degradates, resulting from use of irrigation water containing residues of 0.15 ppm 

following applications on or around aquatic sites. Where tolerances are 

established at higher levels from other uses of fluridone on the following crops, 

the higher tolerance also applies to residues in the irrigated commodity. 

Compliance with the tolerance levels specified below is to be determined by 

measuring only fluridone

Codex maximum residue limits (MRLs), Mexican MRLs, and Canadian MRLs have not 

been established for fluridone residues, so there are no concerns for international 

harmonization.

No residue data were submitted with this request. Several literature and unpublished 

study citations were provided by the petitioner. The conclusions of select unpublished 

studies were briefly summarized and indicated that residues of fluridone on cotton would 

not be expected to exceed the current tolerance based on the proposed Section 18 use.

HED has examined these studies and modified the petitioner conclusions as follows:

In Rainey et al. (1977), total radioactive residues (TRR), determined by liquid 

scintillation counter (LSC), in whole cotton plants grown in soil incorporated treatments 

at up to 0.75 lbs ai/A with C14-fluridone were ≤ 0.0006 ppm 60 days after treatment 

(CA). Additionally, at two sites (CA and MS) applications of up to 0.75 lbs ai/A C14-

fluridone were made as either soil incorporated or soil surface treatments prior to planting 

cotton. Cottonseed was harvested from mature cotton about five months after treatment 

and planting and was delinted prior to LSC analysis. At the CA site, which had a soil 

incorporated treatment, mean TRR in delinted cottonseed were < 0.0028 ppm (corrected 

for controls). At the MS site, control-corrected TRR in delinted cottonseed were < 

0.0009 ppm for soil incorporated treatments and were ≤ 0.0012 ppm for surface 

treatments.

In West and Burger (1978a), a variety of soil types in four sites (NC, MS (2), and AL) 

were surface treated (band application) with one application at either 0.4 lb ai/A or 0.6 lb 

ai/A fluridone. It was not clear from the study report if applications of fluridone were 
Page 5 of 10

made preemergent of cotton plants; however, sampling of mature cottonseed was 

performed approximately five months after treatment. Residues of fluridone in ginned 

cottonseed were nondetectable (<0.01 ppm) from all locations.

In West and Burger (1978b), a variety of soil types in four sites (CA, MS (2), and GA) 

were treated with fluridone as either a soil incorporated preplant application or as a 

surface application. Two applications were made one year apart. The annual (seasonal) 

application rates ranged from 0.6 lb ai/A to 1.0 ai/A of fluridone. Sampling of mature 

cottonseed was performed approximately five months after treatment. Residues of 

fluridone in ginned cottonseed were nondetectable (<0.01 ppm) from all locations.

In Day and West (1975a), a variety of soil types in ten sites (AR (2), AZ (2), GA, NC 

(2), and TX) were treated with one application of fluridone as either a soil incorporated 

preplant application or as a surface application (at planting). Application rates ranged 

from 0.75 lb ai/A to 1.5 ai/A of fluridone. Sampling of cottonseed was performed four to 

seven months after treatment. Residues of fluridone in cottonseed were nondetectable 

(<0.01 ppm) from all locations.

In the Rainey study, cottonseed was delinted (short cotton fibers removed from the seed) 

prior to analysis. Tolerances are established on the commodity cotton, undelinted seed

(short cotton fibers are not removed from the seed). Given the very low levels of TRR

found (<0.0028 ppm) in delinted cottonseed at preplant treatments of up to 0.75 lb ai/A, 

parent fluridone residues would not be expected to exceed the current tolerance 0.1 ppm 

in undelinted cottonseed when fluridone is applied to cotton field soil (or to turnrows and 

ditchbanks adjacent to cotton fields) at a maximum seasonal rate of 0.5 lb ai/A. 

Additionally, it is assumed that in West and Burger (1978a) and West and Burger 

(1978b) that the cottonseed was ginned but not delinted, i.e. the cottonseed was 

undelinted; residues were nondetectable in undelinted seed with soil treatment rates up to 

1.0 lb ai/A fluridone. 

For the purposes of this Section 18 request only, the cited data may be used to conclude 

that the residues of fluridone on cotton would not be expected to exceed the current 

tolerance 0.1 ppm (cotton, undelinted seed) when fluridone is applied preplant or 

preemergent to cotton field soil, or to turnrows and ditchbanks adjacent to cotton fields, 

at a maximum seasonal rate of 0.5 lb ai/A.

Dietary Exposure

Updated dietary exposure assessments are not required to support the proposed Section 

18 use of fluridone on cotton. The most recent assessments (2004 TRED) adequately

cover dietary exposure potential from the proposed use.

Fluridone may be applied directly to water bodies to achieve a target water concentration 

of 10 ppb to 90 ppb for whole lake treatments and 30 to 150 ppb for partial lake 

treatments. Product labels contain restrictions regarding fluridone use near potable water 

intakes. Applications of greater than 20 ppb are not allowed within a quarter mile of 
Page 6 of 10

intakes while applications of 6 to 20 ppb are allowed at intakes. Given this label 

restriction it can be assumed that the concentration of fluridone in drinking water drawn 

from lakes would be 20 ppb or less. A toxic environmental degradate of fluridone, Nmethyl formamide (NMF), may also be found in drinking water as a result of fluridone 

applications. Previous dietary risk estimates from drinking water only (including 

fluridone and NMF), based on surface water estimated concentrations of 20 ppb, were

well below the level of concern. Estimated Margins of Exposure (MOEs) ranged from 

values in the thousands to tens of thousands (the level of concern is MOE< 100).

EPA’s Environmental Fate and Effects Division (EFED) has provided a drinking water 

assessment (DWA) for the proposed Section 18 fluridone use on cotton (D399893 and 

D400398, 4/2/12). Surface water estimated drinking water concentrations (EDWCs) 

were estimated for broadcast spray on (1) cotton fields and adjacent turnrows using the 

FIRST model and (2) ditch banks adjacent to cotton fields using the Tier I Rice model 

and a screening scenario. Ground water EDWCs were estimated using the SCIGROW 

Tier 1 model. EFED concluded that these proposed uses result in water concentrations 

lower than those previously estimated based on direct application to water bodies 

(maximum EDWC of 20 ppb for ground or surface water). Based on the maximum 

fluridone application of 0.5 lb ai/A, the highest EDWCs were for surface water after 

application to cotton fields and turnrows; the estimated peak concentration for acute 

dietary exposure assessment is 9.6 ppm. The estimated annual average concentration for 

chronic assessment is 2.5 ppm. 

The EDWCs provided in EFED’s current assessment are conservative estimates of 

concentrations in drinking water. Degradate of concern N-methyl formamide (NMF) is 

not assessed separately as in the previous DWA. Instead, a total toxic residues approach 

is used and the aqueous photolysis half-life of fluridone is assumed to be stable to 

account for the formation of NMF as the parent compound declines. Dietary exposures 

to drinking water will not be greater than those assessed in 2004 and are not of risk 

concern.

A dietary exposure assessment (using DEEM) was conducted for food only (D299947; 

2004) in association with the TRED. The acute and chronic analyses were conducted 

using tolerance level residues and assumed 100% crop treated (including cotton). 

Resulting exposure estimates for the acute and chronic analyses were <5% of the 

population adjusted dose (PAD) for all population subgroups assessed and are not of risk 

concern. These analyses are conservative so the actual dietary exposure is likely lower 

than the estimates provided. For example, between the years 2005 and 2009 the USDA 

Pesticide Data Program (PDP) analyzed more than 37,000 assorted crop samples for 

fluridone. Low level residues of fluridone were detected in just four of those samples 

(year 2009 potatoes; residues between 0.002 ppm -0.006 ppm). The unrefined (tolerance 

level, 100% crop treated) 2004 dietary exposure assessment is adequate to cover the 

proposed fluridone use on cotton.

Aggregate Risk Assessment
Page 7 of 10

The aggregate risk assessment considers the combined risk from dietary exposure (food 

and water) and any non-occupational (residential) exposures. In the 2004 TRED, the 

aggregate assessment considered combined exposures to fluridone from food, drinking 

water, and swimming in treated water bodies. Aggregate assessments were also 

performed for the aqueous photoproduct NMF for drinking water and swimmer exposure 

(NMF is not found in foods). All aggregate exposures were below the level of concern

(MOEs were all ≥ 1500; the level of concern is an MOE < 100). Since the TRED, a new 

homeowner-use product was registered, but that residential handler exposure has not been 

quantitatively assessed in an aggregate assessment with food and drinking water. 

However, considering the high MOEs for food, water, and residential handling 

exposures, the aggregate exposure will not result in risk estimates of concern. 

The proposed Section 18 use is to cotton in agricultural settings and does not impact 

residential exposure. As described previously in this memorandum, the proposed use 

pattern is not expected to impact dietary exposure estimates. Consequentially, the current 

aggregate exposure assessment for fluridone is not impacted by the Section 18 request. 

Occupational Exposure

HED conducted an occupational assessment for the proposed single maximum seasonal 

application rate of 0.5 lbs ai/A on cotton. Chemigation is prohibited, and the label 

directions clearly direct the user to ground-based application equipment so aerial 

exposure scenarios were not assessed.

Occupational handlers are expected to have exposures consistent with HED’s short- and 

intermediate-term exposure durations. Long-term (more than 6 consecutive months)

handler exposures are not expected. 

The following scenarios are expected from the proposed use on cotton:

1) Mixer/Loaders Using Open Pour loading of liquids, and

2) Applicators (applications will be made in conjunction with planting).

The Agency’s level of concern for occupational exposures and risk estimates is defined 

by the uncertainty factors that are applied to the assessment. For dermal and inhalation 

exposures, the total uncertainty factor that has been applied is 100X [10X interspecies 

factor (animal-to-human) extrapolation and 10X for intraspecies (human) variations]. A 

Margin of Exposure (MOE) greater than 100 would not exceed HED’s level of concern.

The results of the occupational handler assessment are summarized in Table 1 below. The 

resulting MOEs at the baseline scenario (no gloves or respiratory protection) are greater 

than 100 and do not exceed HED’s level of concern. Baseline personal protective 

equipment is proposed on the Section 18 label.
Page 8 of 10

Table 1. Short-/Intermediate-Term Occupational Exposure and Risk Estimates for Fluridone.

Exposure Scenario

Application 

Rate (lb 

ai/gallon)2

Amount 

Handled 

Daily 

(gallons)3

Baseline Unit 

Exposures (ug/lb ai)1 Dose (mg/kg/day) MOE Total MOE6

Dermal Inhalation Dermal4Inhalation4 Dermal5Inhalation5

Dermal + 

* Inhalation No 

Respirator * No Respirator *

No 

Respirator

Occupational Handler Scenarios - Cotton

Groundboom: 

Mixer/Loader (liquids) 0.5 200 220 0.219 0.43 0.0011 140 14,000 140

Groundboom: 

Applicator 0.5 200 78.6 0.34 0.15 0.0017 390 8,800 380

1. Unit Exposures are taken the U.S. Environmental Protection Agency, Office of Pesticide Programs’ “Occupational Pesticide Handler Unit Exposure Surrogate Reference Table” March 2012. Units = 

mg a.i./pound of active ingredient handled. Dermal unit exposure is for use of a single layer of work clothing (long pants, long-sleeved shirt, shoes plus socks). This personal protective equipment 

(PPE) is specified on the product label.

2. Applic. Rate. = Taken from Section 18 request; listed in lbs ai/A

3. Units Treated are taken from information in ExpoSAC policy 9.

4. Average Daily Dose ; Dermal ADD incorporates 39% dermal absorption factor

5. MOE = Margin of Exposure = NOAEL ADD. NOAEL for dermal and inhalation = 15 mg/kg bw/day. 

6 Total MOE = NOAEL (mg/kg/day)/Dermal Dose + Inhalation Dose.
Page 9 of 10

Because of the proposed application methodology, HED does not expect worker postapplication exposure. Fluridone is classified as Toxicity Category III via the dermal 

route of exposure and as Toxicity Category IV for skin irritation potential. It is not a skin 

sensitizer. Therefore, the WPS reentry interval (REI) of 12 hours listed on the original 

label is adequate for the Section 18 proposed uses. 

Conclusions

HED concludes that the application of Brake® (fluridone) to control Palmer amaranth in 

cotton would not result in occupational, dietary (food or water), residential, or aggregate 

(dietary plus residential) exposures or risk estimates of concern provided the Section 18 

supplemental label is modified to specify the maximum seasonal rate allowed [do not 

apply more than 1.56 gallons of Brake per acre (0.5 pounds active ingredient 

fluridone/acre) per year]. 

For the purposes of this Section 18 request only, the cited residue data may be used to 

conclude that the residues of fluridone on cotton would not be expected to exceed the 

current tolerance 0.1 ppm (cotton, undelinted seed) when fluridone is applied preplant or 

preemergent to cotton field soil, or to turnrows and ditchbanks adjacent to cotton fields, 

at a maximum seasonal rate of 0.5 lb ai/A.

Codex maximum residue limits (MRLs), Mexican MRLs, and Canadian MRLs have not 

been established for fluridone residues, so there are no concerns for international 

harmonization.

References

Author Barcode Date Title

M. Lloyd D400522 4/4/12 Fluridone: Occupational Assessment to Support Registration for the 

Proposed Section 18 Use on Cotton.

E. Gelmann D399893, 

D400398

4/2/12 Drinking Water Assessment for the Proposed Section 18 Emergency 

Exemption Use of Fluridone on Arkansas Cotton

C. Olinger, A. 

LaMay, B. Chin

D361849 7/16/09 Fluridone. Human Health Assessment Scoping Document in Support 

of Registration Review

A. LaMay D353630 9/19/08 Fluridone: Occupational and Residential Exposure/Risk Assessment 

for Proposed Use of Fluridone in a Ready-to-Use Formula for 

Residential Ponds.

U.S. EPA NA 9/20/04 Report of the Food Quality Protection Act (FQPA) Tolerance 

Reassessment Progress and Risk Management Decision (TRED) for 

Fluridone

T. Dole D306456 8/17/04 Human Health Risk Assessment for Fluridone TRED

C. Olinger D299947 8/12/04 Fluridone Acute and Chronic Dietary Exposure Assessments for the 

Reregistration Eligibility Decision

Rainey et al. NA 1977 14C Fluridone Residue Study in Cotton and Selected Rotational 

Crops. Unpublished Study. (petitioner citation)

Day and West NA 1975a Residue Data on EL-171 for Weed Control in Cotton. Unpublished 

Study. (petitioner citation)

West and Burger NA 1978a Fluridone and Trifluralin Residues in Cottonseed. Unpublished 

Study. (petitioner citation)

West and Burger NA 1978b Fluridone Residue in Cottonseed. Unpublished Study. (petitioner 

citation)
Page 10 of 10

Appendix 1

Summary of Toxicological Doses and Endpoints for Fluridone for Use in Dietary and Non-occupational 

Human Health Risk Assessments

Exposure/

Scenario

Point of 

Departure

Uncertainty 

Factors RfD/PAD Study and Toxicological Effects

Acute Dietary 

(females 13-49 

years of age )

Dev. NOAEL 

= 125 

mg/kg/day

UFA= 10x

UFH=10x

FQPA SF = 

1X

Acute RfD = 

1.25 

mg/kg/day 

Acute PAD = 

1.25 

mg/kg/day

Developmental Toxicity - Rabbit

LOAEL = 300 mg/kg/day based on 

increased incidences of abortions

Acute Dietary 

(general population)

NOT APPLICABLE. A dose and endpoint were not selected for this population group 

because there were no effects observed in oral toxicology studies including maternal 

toxicity in the developmental toxicity studies in rats and rabbits that are attributable to a 

single exposure (dose).

Chronic Dietary 

(all populations)

NOAEL = 15 

mg/kg/day

UFA= 10x

UFH=10x

FQPA SF = 

1X

Chronic RfD 

= 

0.15mg/kg/da

y

Chronic PAD 

= 0.15 

mg/kg/day

2 yr cancer study in mice 

LOAEL =50 mg/kg/day based on 

increased alkaline phosphatase activity 

and increased incidence of 

heptocellular hyperplasia

Incidental oral

Short- and 

Intermediate-Term 

exposures

NOAEL = 15 

mg/kg/day

UFA= 10x

UFH=10x MOE = 100 2 yr cancer study in mice 

(Same as above)

Cancer (oral) Fluridone is classified as “not likely” to be a human carcinogen. Quantitative cancer risk 

assessment is not required.

Summary of Toxicological Doses and Endpoints for Fluridone for Use in Residential and Occupational 

Human Health Risk Assessments 

Exposure/

Scenario

Point of 

Departure 

Uncertainty 

Factors

Level of 

Concern for 

Risk 

Assessment Study and Toxicological Effects

Dermal 

Short- and 

Intermediate-Term 

NOAEL = 

15 

mg/kg/day

UFA= 10x

UFH=10x MOE = 100 2 yr cancer study in mice 

(Same as above)

Dermal 

Long-Term The endpoint is not applicable because use pattern does not indicate long-term exposure.

Inhalation Short- and 

Intermediate Term

NOAEL = 

15 

mg/kg/day

UFA= 10x

UFH=10x MOE = 100 2 yr cancer study in mice

(Same as above)

Inhalation 

Long-Term The endpoint is not applicable because use pattern does not indicate long-term exposure.

Cancer (dermal and 

inhalation)

Fluridone is classified as “not likely” as a human carcinogen. Quantitative cancer risk 

assessment is not required.

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). 

UFDB=Database uncertainty factor. PAD = population adjusted dose (a = acute, c = chronic) = the NOEL/all appropriate uncertainty

and safety factors. RfD = reference dose. MOE = margin of exposure.