UNITED STATES ENVIRONMENTAL PROTECTION AGENCY 

WASHINGTON D.C., 20460 

OFFICE OF 

CHEMICAL SAFETY AND 

POLLUTION PREVENTION 

PC Code: 080807 

DP Barcode: 407490 

Date: May 28, 2013 

MEMORANDUM 

SUBJECT: 

FROM: 

THRU: 

TO: 

Registration Review- Preliminary Problem Formulation for the Ecological Risk 

Assessment for Simazine (PC Code 080807; DP Barcode 407490) 

Frank T. Farruggia, Ph.D., Biologist ~.: ~~ '-

Melanie Biscoe, Physical Scientist ~--;;:;:) / 

Environmental Risk Branch Ill 

Environmental Fate and Effects Division {7507P) 

Office of Pesticide Programs 

Dana Spatz, Chief~ .... -........................ 

Rosanna Louie-Juzwiak, RAPL 

Melissa Panger, Ph.D., Senior Bio gist 

James Hetrick, Ph.D., Senior Environmental Fate Scient 

Environmental Risk Branch 3 C:::~~~~~ 

Environmental Fate and Effects Division (7507P) 

Molly Clayton, Chemical Review Manager 

Avivah Jakob, Team Leader 

Patricia Parrott, Branch Chief 

Risk Management and Implementation Branch 3 

Pesticide Re-evaluation Division (7508P) 

The Environmental Fate and Effects Division (EFED) has completed the problem formulation for 

the ecological risk and drinking water exposure assessments to be conducted as part of the 

Registration Review of the herbicide simazine. Functioning as the first stage of the risk 

assessment process for registration review, this problem formulation provides an overview of 

what is currently known about the environmental fate and ecological effects associated with 

simazine and its degradates. It also describes the preliminary ecological risk hypothesis and 

analysis plan for evaluating and characterizing drinking water exposure and risk to non-target 

1 

• 
2 

species and the environment in support of the registration review of simazine. Finally, this

document identifies data gaps for ecological risk assessment and recommends studies to

address remaining uncertainties.  

As noted in Section 7, Preliminary Identification of Data Gaps, the database for environmental

fate and transport for simazine is sufficient for risk assessment such that, with the exception of

the need for an updated analytical method for soil, no additional data are needed at this time.

With regard to the ecological effects database, while the database is incomplete, no additional

data are needed at this time. Please refer to this section for additional details.

1. Introduction

The purpose of this problem formulation is to provide an understanding of the environmental

fate and ecological effects of simazine in support of Registration Review.  

Simazine is a non‐selective systemic triazine herbicide labeled for pre‐ and post‐emergent

applications to control annual and perennial grasses and broadleaf weeds on a variety of crops

and non‐agricultural use sites.  The mechanism of action of simazine involves inhibition of

photosynthesis via disruption of CO2 fixation and production of intermediary energy

components including ATP and NADPH.

1.1 Previous Assessments

A drinking water assessment and an ecological risk assessment for registered uses was

conducted as part of EPA’s Reregistration Eligibility Decision (RED) for simazine in 2006 (DPs

324226, 325446, 307018)1.  In 2006 EPA also conducted a chloro‐s‐triazine cumulative drinking

water assessment inclusive of simazine (DP 317976).  Based on data needs identified in the

RED, a Data‐Call‐In (DCI) was issued on August 19, 2008 that required the simazine registrants

to conduct several environmental fate and ecological effects studies, as well as establish a

simazine drinking water monitoring program.  

   

The RED assessment identified risks to:  

Aquatic Organisms:

 Amphibians (uncertainty); the RED stated that future studies on atrazine’s potential

sublethal effects to amphibians, specifically impacts on gonadal development in frogs,

may be applicable to simazine because the two chemicals share a similar mechanism of

toxicity, a similar mechanism of herbicidal action, and similar degradates.  

 Aquatic non‐vascular and vascular plants, and communities.

 

1

 U.S. EPA. 2005. Interim Reregistration Eligibility Decision: Environmental Fate and Effects Chapter, 

Environmental Fate and Ecological Risk Assessment for Simazine C-Chloro-N,N-diethyl-1,3,5-triazine-2,4-diamine 

(PC 080807). 
3 

Terrestrial Organisms:

 Chronic risk to both birds and mammals, based on sublethal effects on weight gain

 Non‐target terrestrial plants, including both monocots and dicots

In addition to the potential risks to non‐target organisms noted above, the endangered

species level of concern was exceeded for the following taxa and use scenarios:

 Freshwater fish – granular application for nonselective weed control on turf and other

non‐crop land;

 Freshwater invertebrates – all non‐granular application on citrus, pine trees, nuts,

peaches, apples, and corn; granular application for nonselective weed control on turf

and other non‐crop land;

 Vascular aquatic plants – all non‐ granular application on citrus, nuts, peaches, and corn;

granular application for nonselective weed control on turf and other non‐crop land as

well as apples;

 Birds – non‐granular application for all uses;

 Mammals – non‐granular and granular application for all uses; and

 Monocot and dicot terrestrial plants – non‐granular and granular application for all uses.

The RED required revisions to simazine labels that included mitigation measures to address

non‐target terrestrial exposures to animals and plants.  These mitigation measures were placed

on the label in 2011 and were as follows:

 Prohibit use as “non‐selective weed control on non‐crop land” on product labels;

 Prohibit formulation of simazine into granular formulations for agricultural use; and

 Reduce the maximum application rates to typical rates, and harmonize application

rates on simazine product labels.

o Single application rates for use on corn set to 2.0 pounds of active ingredient

(lb a.i.)/acre, and a maximum of 2.5 lb a.i./acre/year.

o Further restrict use on corn in areas with highly erodible soils (<30% plant

residue cover) to a single preemergence application of 1.6 lb a.i./acre/year.  

1.1.1 Drinking Water Exposure

The RED, subsequent DCI, and Memorandum of Agreement with the simazine registrants also

required the registrants to establish an on‐going drinking water monitoring program, called the

Simazine Monitoring Program (SMP).  In this program, simazine data collected by states under

the Safe Drinking Water Act (SDWA) are evaluated to determine whether a particular

Community Water System (CWS) has detections of simazine and its two chlorinated degradates

approaching the simazine Maximum Contaminant Level Goal (MCLG) of 4 μg/L for finished

drinking water.  If finished drinking water in a CWS has an annual average of simazine and its

two chlorinated degradates at or above 2.6 μg/L under SDWA, registrants are required to

monitor the raw (untreated) and finished drinking water in that CWS for five years on a weekly

basis during the peak simazine use season and biweekly during the rest of the year.  SMP
4 

monitoring samples are analyzed for simazine, atrazine, and their chlorinated degradates, as all

are considered equally toxic to humans.  More specific details concerning the SMP may be

found in the simazine RED.  More information on the AMP as well as the monitoring data

collected the SMP and the AMP may be found on EPA’s Atrazine Updates Website,

http://www.epa.gov/oppsrrd1/reregistration/atrazine/atrazine_update.htm#cws.

1.1.2 Endangered Species Assessments

EPA conducted several simazine ecological risk assessments for federally‐listed endangered

species from 2000‐2010.  EPA conducted an assessment for the Endangered and Threatened

Salmon and Steelhead in 20032

.  The Agency made a “no effect” determination for Pacific

anadromous salmonids.

EPA conducted an assessment for the California Red‐legged Frog (Rana aurora draytonii) in

20073

.  The Agency made a Likely to Adversely Affect (LAA) determination for the aquatic‐phase

California Red‐legged Frog, and also made a LAA determination for the terrestrial‐phase

California Red‐legged Frog for chronic direct effects and indirect effects.  Additionally, the

Agency determined that there is the potential for modification of designated critical habitat for

the California Red‐legged Frog from the uses of simazine in California.

In 2007, EPA also conducted an assessment for the Barton Springs Salamander (Eurycea

sosorum)

4

.  The Agency made a “no effect” determination for the Barton Springs salamander.

EPA conducted an assessment for the Delta smelt (Hypomesus transpacificus) in 20105.  The

Agency made a LAA determination for the Delta Smelt from the use of simazine in California.  

Additionally, the Agency determined that there is the potential for modification of designated

critical habitat for the Delta Smelt from the uses of simazine in California.

 

2 USEPA. 2003. Simazine: Analysis of Risks to Endangered and Threatened Salmon and Steelhead. Environmental

Fate and Effects Division, Office of Pesticide Programs, Washington, D.C.  20460

3 USEPA. 2007. Risks of Simazine Use to California Red‐legged Frog (Rana aurora draytonii). Environmental Fate

and Effects Division, Office of Pesticide Programs, Washington, D.C.  20460

4 USEPA. 2007. Risks of Simazine Use to Barton Springs Salamander (Eurycea sosorum). Environmental Fate and

Effects Division, Office of Pesticide Programs, Washington, D.C.  20460

5 USEPA. 2010. Risks of Simazine Use to Federally Threatened Delta Smelt (Hypomesus transpacificus).

Environmental Fate and Effects Division, Office of Pesticide Programs, Washington, D.C.  20460
5 

1.2 Stressor Source and Distribution

Simazine is part of the triazine herbicide family (such as atrazine, cyanazine, propazine) in the

Weed Science Society group 5 with the mechanism of action of inhibiting photosynthesis at

photosystem II. The structure of simazine, as well as the chemical name and other identifiers

are provided below.

  

2‐chloro‐4,6‐bis(ethylamino)‐s‐triazine

CAS Number: 122‐34‐9

Simazine can be used on post‐emergent weeds, applied as a foliar herbicide, but it is also

readily absorbed through the root system, so it is primarily applied as a pre‐plant incorporated

or soil‐applied herbicide. Simazine is registered for uses on terrestrial food crops, terrestrial

nonfood crops, non‐crop sites, forestry, and aquatic nonfood sites.   

Simazine is formulated as an emulsifiable, soluble or flowable concentrate, or as a water

dispersible granule.  Simazine may be applied by broadcast, sprinkler irrigation, ground

chemigation, ground and canopy spray, or sprayed from aircraft.  Simazine is registered for use

on the following agricultural commodities: alfalfa, almond, apple, avocado, blueberry, broccoli,

Brussels sprouts, cabbage, caneberries, cherry, citrus, corn (field, sweet), cranberry, filbert

(hazelnut), grapefruit, grapes, kale, kohlrabi, lemon, macadamia nut (bushnut), nectarine, olive,

orange, peach, pear, pecan, persimmon, plum, strawberry, and walnut (English/black). It is also

registered for use on nursery stock (ornamental plants, ornamental woody shrubs and vines,

ornamental trees), forestry (black walnut, oak, loblolly pine, slash pine, white pine), christmas

tree plantations, shelterbelt plantings, turf (golf course, ornamental, sod farms, residential

lawns), ornamental ponds and aquaria, uncultivated agricultural areas, farm buildings, and

other non‐agricultural areas (Appendix D). The risk assessment will rely upon the labeled rates

and usage information summarized in (Appendix E).

Based on a report from the Biological and Economical Analysis Division (USEPA 2012), between

2006‐2010, the annual total agricultural usage averaged approximately 5 million pounds of

simazine active ingredient (a.i.) for 4 million treated acres. During this time frame, the crops

with the most use in terms of total pounds of active ingredient were corn (53%), oranges (22%),

and wine grapes (7%). The crop with the most use in terms of total area treated was also corn

(71%). On average, the states with the most agricultural usage in terms of pounds a.i. applied

are California (23%), Illinois and Florida (16% each), and Indiana (13%) (Proprietary Data, 2006‐

2010).  There is uncertainty as to the total usage of simazine in non‐crop areas (e.g., forestry,
6 

ornamentals, turf, and aquatic areas), as these data are not currently available for non‐

agricultural uses.

The food and non‐food uses with the highest application rates (based on application and use

rates) for simazine according to the current label use information are provided in Appendix E.

These uses and rates will be used to estimate exposure and potential risk to non target

organisms.

2. Environmental Fate Summary

Simazine is mobile and persistent in the environment. The main routes of dissipation are

microbial degradation under aerobic conditions, runoff, and leaching. Because of its persistence

and mobility, simazine can move into surface and groundwater. This is confirmed by the

detections of simazine in surface water and groundwater in monitoring data. Summaries of the

environmental fate data are shown in Table 1.  

There is no evidence that simazine degrades by abiotic hydrolysis at pH 4, 7, and 9 (MRID

00027856). Simazine is persistent to direct photodegradation in water (t1/2 > 386 days; MRID

42503708), and persistent to photodegradation on soil (t1/2= 132 days; MRID 42739101).  It is

moderately soluble in water with an aqueous solubility of 3.5 mg/L at 20oC.

Simazine is persistent in aerobic loam soils (t1/2 ranges from 89 to 859 days) and aerobic aquatic

environments (t1/2= 97 days; MRID 43004501; 46561301; 43004502). Simazine is also persistent

in anaerobic aquatic (t1/2 > 1,766 days) and potentially persistent in anaerobic soil environments

(no degradation occurred within a 51‐day study duration) (MRIDs 40614411, 00027857).   

Soil sorption coefficients for simazine (KF) range from 0.5 to 4.3 (

1

/n=0.79‐1.40) (MRID

41442903). The average Koc of 123.25 ml/g‐OC (n=4; MRID 41442903) indicates a FAO mobility

classification of moderately mobile in soil6

.  

Field dissipation studies show that simazine dissipation is driven by microbial‐mediated

degradation and by leaching.  The half‐life of simazine in one terrestrial field study was 36 days

in the top 8 inches of soil in bare ground plots in Florida (MRID 40634202).  Another terrestrial

field study detected simazine 480 days after application in 12 to 24 inches of soil in Nebraska

(MRID 00027863).  The half‐life in three aquatic field dissipation studies in multiple states

ranged from 10 to 700 days (MRIDs 00027829, 40614420, 40614422). Microbial‐mediated

degradation is an important route of dissipation in the cited aquatic field studies. The half‐lives

in the terrestrial and aquatic field dissipation studies were often shorter than the half‐lives in

the laboratory studies, which may be attributed to the availability of multiple routes of

dissipation and degradation in the field dissipation studies.

 

6 Food and Agriculture Organization of the United Nations (FAO). 2000. Assessing Soil Contamination: A Reference

Manual.  FAO Pesticide Disposal Series 8.   
7 

With low vapor pressure (6.1 x 10‐9 mm Hg at 20C) and low Henry's Law Constant (3.2 x 10‐10

atmm3/mol at 25C), volatilization losses of simazine from soil and water systems are expected

to be insignificant compared to dissipation by chemical degradation and metabolism7.  The low

octanol water partitioning coefficient (Kow = 122) and the steady‐state and kinetic

Bioconcentration Factors (BCFs) reported in Table 1 indicate that simazine has low potential to

bioaccumulate in fish (MRID 00043668)8.

Table 1 . Environmental Fate Parameters for Simazine

Parameter Value Source and Classification

Persistence      

Hydrolysis (20C) Stable at pH 4, 7, and 9

MRID 00027856

Acceptable

Aqueous photolysis half‐life (25C) 386‐3496 days* at pH 7

MRID 42503708

Acceptable

Soil photolysis half‐life (25C) 132 days

MRID 42739101

Acceptable

Aerobic soil metabolism half‐life

137 days (20°C)

MRID 46561301

Supplemental

80 days (25°C)

MRID 00158638

Supplemental

89 days (25°C)

MRID 43004501

Supplemental

Anaerobic soil metabolism (25°C) No degradation within  

51‐day study duration

MRID 00027857

Supplemental

Aerobic aquatic metabolism half‐life

(25°C) 97 days MRID 43004502

Acceptable

Anaerobic aquatic metabolism half‐

life (25C)

1766‐3614 days**             

(sandy clay)

MRID 40614411

Acceptable

Mobility      

KF

4.3, 1

/n = 0.84 (clay)

0.7, 1/n = 1.08 (sand)

1.3, 1/n = 0.79 (sandy loam)

0.5, 1/n = 1.40 (loam) MRIDs 41442903, 41257903

 

7

 U.S. EPA. 2005. Interim Reregistration Eligibility Decision: Environmental Fate and Effects Chapter, 

Environmental Fate and Ecological Risk Assessment for Simazine C-Chloro-N,N-diethyl-1,3,5-triazine-2,4-diamine 

(PC 080807). 

8

 U.S. EPA. 2005. Interim Reregistration Eligibility Decision: Environmental Fate and Effects Chapter, 

Environmental Fate and Ecological Risk Assessment for Simazine C-Chloro-N,N-diethyl-1,3,5-triazine-2,4-diamine 

(PC 080807). 
8 

Table 1 . Environmental Fate Parameters for Simazine

Parameter Value Source and Classification

Kfoc

153 (clay) Acceptable

123 (sand)   

114 (sandy loam)   

103 (loam)   

Field Dissipation      

Terrestrial field dissipation half‐life

and/or leaching depth

36 days in 0‐8 inches of  

bare soil (Florida)

MRID 40634202

Supplemental

Present at 480 days in 18‐24 inches

of soil (Nebraska)

MRID 00027863†

Supplemental

Aquatic field dissipation half‐life;

leaching depth

60 to 700 days‡

MRID 00027829

in lakes Supplemental

10 days (Iowa)  

man‐made pond – water MRID 40614422

80 days (Iowa)   Supplemental

man‐made pond – sediment   

Bioaccumulation

Fish bioconcentration factor BCFsteady state = 4.92 (whole fish)

BCFkinetic = 7.30 (whole fish) MRID 00043668           

Supplemental

Depuration rate constant 0.06

* Analysis conducted for one soil using Normal Phase Thin Layer Chromatography resulted in a half‐life of 386

days, while analysis using Reverse Phase Thin Layer Chromatography resulted in a half‐life of 3,946 days.

** Analysis conducted for one soil using a chloroform:methanol:formic acid:water 80:15:4:2 v:v:v:v solvent system

resulted in a half‐life of 1,766 days, while analysis using a solvent system of tolulene:acetone 75:25 v:v resulted in

a half‐life of 3,614 days.

†

This is the only soil compartment analyzed; simazine concentrations were not measured at day 0 and

consequently the half‐life was not calculated.  Plant bioassay was used to determine simazine or simazine‐

equivalents in other soil compartments.   

‡

Sediment samples were not analyzed.

2.1 Degradation Products

There are two main types of degradation products for simazine. The first type of degradation

products are formed through dealkylation of the amino groups. The second type of degradation

products are formed through substitution of a chlorine by a hydroxy group. These two types of

degradation products can be formed through abiotic and microbial‐mediated processes. Two

simazine degradation products, 6‐Deisopropylatrazine (DIA) and 2‐Chloro‐4,6‐diamino‐s‐triazine
9 

(DDA), are also degradation products of atrazine and propazine. Chemical names, formulas, and

degradation products of simazine are shown in Appendix A, Table A‐1.

Environmental fate data indicate that DIA and hydroxysimazine (HS) are the major degradates

of simazine (>10% applied a.i.). DIA and HS were detected in all environmental fate laboratory

studies with the exception of the hydrolysis study and the aqueous photolysis study (MRIDs

00027856, 42503708). DIA and HS were the only degradates reported in field studies (Table 2).  

For studies limited to several months, DIA was usually detected at greater concentrations than

HS.  DIA has been detected in surface water monitoring conducted for the SMP, although these

detections are not likely solely due to simazine degradation as atrazine is typically applied in the

CWS watersheds where simazine is used. Note that HS data are not reported for the SMP, as it

is not considered of concern for human health (USEPA 20029

).  

The presence of DIA as a major degradate in several laboratory studies and field data is

important because DIA is mobile in soil and therefore susceptible to runoff and leaching (Table

2) 10.  Runoff and leaching of DIA has the potential to increase human exposure to total chloro‐

triazines (TCT) through drinking water.  Simazine degradation to DIA also has the potential to

adversely impact non‐target terrestrial mammals and freshwater aquatic organisms (see

Section 4.2).   

DIA formation was 12.5 to 16.1 percent of applied simazine after 30 days of photodegradation

on soil (MRID 42739101).  DIA was also formed in the dark control of this study (albeit at a

lower percentage of applied simazine), which is likely the result of aerobic soil metabolism due

to the use of microbially‐active soil in the study.  This is supported by the occurrence of DIA as a

major and minor degradate in the aerobic soil metabolism studies (MRIDs 46561301,

00158638, 43004501).

In one study DIA formation was 17.5 percent of applied simazine after 90 days of aerobic soil

metabolism (MRID 46561301) and in another study 10.3 percent of applied simazine after 60

days of aerobic soil metabolism (MRID 00158638).  A third aerobic soil metabolism study

detected DIA but could not quantify the amount present because there was an insufficient

amount of analyte in the test sample.  DIA was a minor degradate in the anaerobic soil

metabolism, anaerobic aquatic metabolism and aerobic aquatic metabolism studies (MRIDs

00027857, 40614411, 43004502).  In the anaerobic soil metabolism study, DIA formation was

7.7 percent of applied on day 0 of the study. In the anaerobic aquatic metabolism study, DIA

formation was 6.87 percent of applied simazine after 365 days.  In the aerobic aquatic

metabolism study, DIA formation was 1.6 percent of applied simazine on days 0 and 7 of the

study.

HS is slightly to hardly mobile in soil and therefore not expected to be susceptible to runoff or

 

9

 USEPA, 2002. The Grouping of a Series of Triazine Pesticides Based on a Common Mechanism of Toxicity. U.S. 

Environmental Protection Agency, Office of Pesticide Programs, Human Health Division. 10 Food and Agriculture Organization of the United Nations (FAO). 2000. Assessing Soil Contamination: A Reference

Manual.  FAO Pesticide Disposal Series 8.   
10 

leaching (Table 2)

11. Although HS is a major degradate of simazine, like other non‐chlorinated

simazine degradates, HS is not considered to be toxic to humans or non‐target aquatic or

terrestrial organisms.  Information on the extent of formation of HS in the laboratory and field

studies is located in Table 2.  

DDA is a minor degradate (<10% applied a.i.) of simazine, and its mobility is similar to that of

DIA (Table 2)

12.  Unlike the other minor degradates identified in the laboratory and field

studies, DDA is a chlorinated degradate of simazine and therefore considered to be as toxic as

simazine to humans. Runoff and leaching of DDA has the potential to increase human exposure

to total chloro‐triazines (TCT) through drinking water, although not to as great an extent as DIA.  

DDA is not expected to adversely impact non‐target terrestrial or aquatic organisms based on

its ecotoxicity profile (see Section 4.2).   

DDA formation was 1.0 percent of applied simazine after 30 days of photodegradation on soil

(MRID 42739101).  In aerobic soil metabolism studies, DDA formed at maxima of 9.2 percent of

applied simazine after 270 days and 1.4 percent of applied simazine after 365 days (MRIDs

46561301 and 00158638).  Another aerobic soil metabolism study did not detect DDA (MRID

43004501).  DDA was detected in the anaerobic soil metabolism and anaerobic aquatic

metabolism studies (MRIDs 00027857, 40614411).  In the anaerobic soil metabolism study, DDA

formation was 2.2 percent of applied on day 0 of the study. In the anaerobic aquatic

metabolism study, DDA formation was 0.62 percent of applied after 30 days.  DDA was not

detected in the aerobic aquatic metabolism study (MRID 43004502).  DDA was also not

detected in the terrestrial and aquatic field dissipation studies.  DDA has been detected in

surface water monitoring conducted for the SMP, although these detections are not likely

solely due to simazine degradation as atrazine is typically applied in the CWS watersheds where

simazine is used.

Other minor degradates identified in the environmental fate studies include s‐Triazin‐2‐ol, 4‐

amino‐6‐(ethylamino)‐ (8CI) (DIHA), Ammeline (OAAT), 2‐Amino‐4‐ethylamino‐6‐methoxy‐s‐

triazine (MAET), o‐methyl hydroxysimazine, and 2‐chloro‐4‐ethylamino‐6‐hydroxyethylamino‐s‐

triazine.   

Table 2. Identification of Simazine Degradation Products in Environmental Fate Studies  

Study Degradation

Products

Maximum Percentage of

Applied Simazine (day) References

Hydrolysis   None NoneMRID 00027856

Acceptable

Photodegradation in

Water

No known

degradates

identified

No known degradates

quantified

MRID 42503708

Acceptable

 

11 Food and Agriculture Organization of the United Nations (FAO). 2000. Assessing Soil Contamination: A Reference

Manual.  FAO Pesticide Disposal Series 8.    12 Food and Agriculture Organization of the United Nations (FAO). 2000. Assessing Soil Contamination: A Reference

Manual.  FAO Pesticide Disposal Series 8.   
11 

Table 2. Identification of Simazine Degradation Products in Environmental Fate Studies  

Study Degradation

Products

Maximum Percentage of

Applied Simazine (day) References

Photodegradation

on Soil 

DIA 12.5‐16.1 (30 d) MRID 42739101

Acceptable HS 2.2 (30 d)

DIHA 1.7 (30 d)

DDA 1.0 (30 d)

Aerobic Soil

Metabolism

DIA 17.5 (90 d) MRID 46561301

Supplemental DDA 9.2 (270 d)

HS 4.3 (180 d)

2‐chloro‐4‐

ethylamino‐6‐

hydroxyethylamino‐

s‐triazine

1.6 (180 d)

DIHA 0.1 (270 d)

OAAT < 0.1 (270 d)

DIA 10.3 (60 d) MRID 00158638

Supplemental HS 4.0 (365 d)

DDA 1.4 (365 d)

DIHA 0.7 (365 d)

2‐chloro‐4‐

ethylamino‐6‐

hydroxyethylamino‐

s‐triazine

3.1 (28 d)

OAAT 0.2 (365 d)

HS 62.08 (371 d) MRID 43004501

Supplemental DIHA 4.88 (371 d)

DIA Not quantified

Anaerobic Soil

Metabolism

DIA 7.7 (0 d) MRID 00027857

Supplemental DDA 2.2 (0 d)

HS 5.6 (70 d)

DIHA 2.8 (0 d)

Anaerobic Aquatic

Metabolism

HS 6.98 (365 d) MRID 40614411

Acceptable DIA 6.87 (365 d)

DDA 0.62 (30 d)

Aerobic Aquatic

Metabolism

HS 11.7 (30 d) MRID 43004502

Acceptable MAET 0.4 (14 d and 21 d)

o‐methyl

hydroxysimazine 0.4 (14 d)
12 

Table 2. Identification of Simazine Degradation Products in Environmental Fate Studies  

Study Degradation

Products

Maximum Percentage of

Applied Simazine (day) References

DIA 1.6 (0 d and 7 d)

Terrestrial Field

Dissipation

DIA 1.8 (15 d) (0‐8 inches) MRID 40634202

Supplemental HS 4.9 (31 d) (0‐8 inches)

Degradates not extracted, analyzed, or reported.

MRID 00027863

Supplemental

Aquatic Field

Dissipation

DIA 8.0 (90 d) MRID 00027829

Supplemental Florida

8.0 (27, 60, 90, 120, 150 d)

Washington

10.0 (120 d, 400 d)

Oklahoma

6.0 (150, 200 d)

Arizona

4.0 (21, 60, 90 d)

New York

DIA 36.8* (6 d) MRID 40614420

Supplemental HS 6.9* (6 d)

DIA 2.6 (1 d)** water MRID 40614422

Supplemental HS 2.8 (1 d)** water

* Percent applied based on an initial application of 2.04 mg/L, as the 0‐day simazine concentration

measurement was below the LOD.  An additional application of simazine was made on day 7 of the

study.  Maximum degradate concentrations in water during the study period were 1.02 ppm on

day 9 for DIA and 0.81 ppm on day 8 for HS.   

** An additional simazine application was made on day 2 of the study.  Maximum degradate

concentrations during the study period were 0.13 ppm on days 3 and 7 for DIA and 0.3 ppm on

day 242 for HS.  Maximum degradate concentrations in sediment during the study period were 0.1

ppm on day 2 for DIA and 0.22 ppm on day 365 for HS.

3. Water Monitoring Data

Simazine surface water and groundwater monitoring data prior to 2006 were analyzed in the

USEPA Simazine IRED (2006).  As a result of the 2006 IRED, simazine registrants were required

to establish a monitoring program that focused on drinking water exposures in Community

Water Systems (CWS).  This program is called the Simazine Monitoring Program (SMP).  In this

program, simazine registrants are required to intensively monitor a CWS when quarterly Safe

Drinking Water Act (SDWA) monitoring data collected in that CWS result in an annual average
13 

of 2.6 ppb or greater for simazine and its two chlorinated degradates.  For the CWS where

intensive monitoring is required, registrants monitor for simazine and its degradates in ambient

and finished drinking water in the CWS on a weekly basis during the peak simazine use season

and biweekly the rest of the year.   

In 2003, a drinking water program similar to the SMP was established for atrazine.  In this

program, called the Atrazine Monitoring Program (AMP), registrants collect ambient and

finished drinking water data on a weekly and bi‐weekly basis.  Though this program is targeted

to atrazine use areas, the CWS monitoring data are also analyzed for simazine and its chloro‐s‐

triazine degradates DIA, and DDA.

In addition to the data from the SMP and the AMP, surface water and groundwater monitoring

data from the National Water‐Quality Assessment Program (NAWQA), the USGS‐EPA Pilot

Monitoring Program, the USDA PDP Program, the California Surface Water and Groundwater

Monitoring Programs, and additional simazine surface water and groundwater data submitted

to OPP by states, tribes, and the registrants will be reviewed and included in the drinking water

assessment and the ecological risk assessment, when appropriate.  The USGS‐EPA Pilot

Monitoring Program, the USDA PDP Program, the SMP and the AMP monitor finished drinking

water as well as ambient surface water. The NAWQA and the USDA PDP Programs also monitor

for simazine in groundwater as well as surface water.   

Programs monitoring for simazine in surface water vary regarding their objective and

monitoring strategy. Programs such as the NAWQA, the California Surface Water, and the

USGS‐EPA Pilot Monitoring Program were developed to assess general pesticide occurrence in

ambient surface water. In contrast, other monitoring programs, such as the SMP and AMP,

were targeted to simazine and atrazine use areas, respectively.  A key difference among the

monitoring programs is the annual sampling frequency at each sampling station. The sampling

frequency will be an important consideration in quantitative interpretation of the pesticide

concentrations from monitoring data.

EPA encourages states and tribes to submit additional monitoring data for simazine and its

degradates during the Preliminary Work Plan comment period.  EPA will consider these data in

the drinking water assessment and the ecological risk assessment.  

4. Receptors

Assessment of risk is based on the most sensitive species tested for terrestrial and aquatic

organisms. The following sections outline the most sensitive toxicity data for simazine and its

degradates of concern.  

4.1 Parent: Simazine

The acute and chronic toxicity values for the most sensitive aquatic animals and plants tested
14 

are presented in Table 3. The most sensitive terrestrial animal acute and chronic toxicity values

are presented in Table 4, and the terrestrial plant toxicity data are presented in Table 5. The

complete available ecotoxicity dataset including open literature studies can be found in the

appendices of the Endangered Species risk assessment for the Red‐legged Frog (USEPA 200713).

Prior to conducting the risk assessment for registration review, a new ECOTOX report will be

generated and these appendices will be updated.

Aquatic Toxicity Summary

A considerable number of aquatic toxicity and field studies are available for simazine.  Reported

acute toxicity values generally exceed the water solubility limit of simazine (approximately 3.5

mg/L at 20o C).  While simazine concentrations in water would appear to be stable to hydrolysis

and photolysis for the duration of the acute static studies, the actual exposure levels are

uncertain because mean‐measured concentrations are not available, and precipitation is

frequently reported in the acute studies.  Test concentrations were rarely measured to verify

exposure levels; therefore, a high degree of uncertainty exists for the freshwater toxicity data

for simazine.  As such, studies with reported LC50 values > 100 μg/L are highly uncertain.   

Table 3 summarizes the most sensitive ecological toxicity endpoints for aquatic organisms.

Below the table an additional summary discussion of simazine toxicity to the listed taxonomic

groups is provided.

Table 3. Summary of the Most Sensitive Endpoints from Aquatic Toxicity Studies for Simazine

Assessment

Endpoint Acute/ Chronic SpeciesTGAI/TEP % a.i.

Toxicity

Value Classification

Citation  

or MRID

Number1

Comment

Freshwater

fish  

Acute Fathead Minnow,

Pimephales

promelas

(TGAI)

96‐hour LC50

= 6,400 μg

a.i./L  

Moderately

Toxic

MRID

00033309

Supplemental:  

Nominal

concentrations; no

raw data provided

Chronic Fathead Minnow,  

Pimephales

promelas  

(80% formulated

product)

NOAEC = 960

μg a.i./L

LOAEC =

2,000 μg

a.i./L

NA MRID

00043676

Supplemental:;

Raw data

unavailable; F0

generation used

10 month old fish;

No hatch data.

Freshwater

invertebrates

Acute Daphnid,

Daphnia magna

(TGAI)

48‐hour EC50

2

= 1,000 μg

a.i./L  

Highly Toxic MRID

45088221

Supplemental:  

Nominal

concentrations; no

raw data provided.

Chronic Daphnid,

Daphnia magna

(80% formulated

product)

Calculated

NOAEC = 40

μg a.i./L

NA  ‐ Calculated from D.

magna ACR3 from

atrazine data,

using the D.

magna acute

endpoint of 1000

 

13 USEPA. 2007. Risks of Simazine Use to California Red‐legged Frog (Rana aurora draytonii). Environmental Fate

and Effects Division, Office of Pesticide Programs, Washington, D.C.  20460
15 

Assessment

Endpoint Acute/ Chronic SpeciesTGAI/TEP % a.i.

Toxicity

Value Classification

Citation  

or MRID

Number1

Comment

μg a.i./L.

Estuarine/

marine fish

Acute Seabream  

(Sparus aurata)

yolk‐sac larvae  

(TGAI)

72‐ hour LC50

= 4,190 μg

a.i./L

Moderately

Toxic

E76270

Arufe et

al., 2004  

Supplemental:  

Nominal

concentrations;  

Chronic Seabream  

(Sparus aurata)

Calculated using

Fathead minnow

ACR4 (6.7)

NOAEC = 625

μg a.i./L

NA ‐‐  Calculated data

based on acute

to chronic ratio

from freshwater

data4

Estuarine/

marine

invertebrates

Acute Eastern oyster,  

Crassostrea virginica

(TGAI)

96‐hr EC50 =

>3700 μg

a.i./L

Moderately

Toxic

MRID

42503703

Acceptable:

6.8% reduction

in shell growth

at the highest

test

concentration

Chronic  ‐‐   

No Data

NA ‐‐  ‐‐ 

Aquatic plants Vascular Duckweed,  

Lemna gibba

(TGAI)

Freshwater

14‐day IC50 =

140 μg a.i./L  

NOAEC = 54

μg a.i./L  

NA MRID

42503704

Acceptable:  

LOAEC of 110 μg/L

based on

reduction in frond

number

Non‐vascular Pseudokirchneriella

subcapitata

Oxygen

Evolution

Test  

IC50 = 2.24

ug/L  

Bottle Test

(Biomass)

IC50 =  0.614

ug/L  

NA Turbak et

al. 1986

ECOTOX#

11780

Supplemental/

Quantitative:  

Nominal

concentrations; no

raw data provided;

no information

provided to

determine NOAEC

or EC05

1 ECOTOX references are designated with an E followed by the ECOTOX reference number.   2

Threshold Limit, term used by authors to identify the threshold concentration in which immobility was observed

at a certain level, in this case, 50% immobilization which is for our purpose, the same as an EC50 and used in

calculations in the same way. 3

ACR calculations from atrazine data:  data from MRIDs 45087413 and 00024377 showed atrazine acute and

chronic toxicity endpoints for D. magna of 3500 and 140 μg a.i./L, respectively; therefore, 3500/140 = 25. 4

ACR calculations for fathead minnow simazine toxicity data above:  6400/960 = 6.7.

Fish:  

It appears that simazine is acutely toxic to some freshwater fish and aquatic invertebrates in

the range of 1 to 10 mg/L. While there are no submitted freshwater fish early life‐stage tests
16 

using the TGAI, two fish life‐cycle tests with fathead minnow were submitted for simazine

formulated products; however, these have been reclassified as supplemental and can only be

used in a qualitative manner in the risk assessment. The decision to reclassify these studies

from acceptable to supplemental was based on the lack of raw data for the study, mature fish

used to start the study were not less than 24 hr old embryos, and lastly, the total number of

spawns and eggs, as well as survival, is not clear from the study report. A NOAEC value of 960

μg a.i./L was selected, based on 12% reduction in growth (length) to 30‐day old fry at a

continuous exposure treatment level of 2,000 μg a.i./L (MRID 00043676). In the absence of new

850.1500 and/or 850.1400 studies, open literature data for simazine as well as available data

for other triazines will be evaluated for use in the risk assessment.  

In addition to registrant submitted studies, data available from the open literature show

sublethal effects to freshwater fish at lower concentrations than those previously used in risk

assessments (e.g., MRID 00043676). Although these studies (see USEPA 200714) report

potentially sensitive endpoints (olfactory detection of female priming pheromone and priming

response of male), effects on survival, growth, or reproduction were not observed in the

available full life‐cycle studies, and so they will not be used in RQ calculations, but will be useful

for risk characterization.  

Aquatic Invertebrates:  

Acute toxicity data for simazine are available for daphnids (Daphnia magna), seed shrimp

(Cypridopsis vidua), scuds (Gammarus lacustris and G. fasciatus), stoneflies (Pteronarcys

californica), sowbugs (Asellus brevicaudus), glass shrimp (Palaemonetes kadiakensis) and

crayfish (Orconectes nais), and the estuarine/marine species Eastern oyster (Crassostrea

virginica). Results of acute toxicity tests are found in USEPA 2007. Based on these data simazine

is classified as highly toxic to freshwater invertebrates and moderately toxic to saltwater

invertebrates on an acute exposure basis.  

No freshwater invertebrate life‐cycle test using the TGAI was submitted for simazine; however,

one was submitted that used the simazine formulated product Aquazine (80% formulation;

MRID 00043676). No treatment‐related adverse effects to D. magna, including parental

mortality and offspring production, occurred during the 21‐day study at the highest

concentration tested, 2,000 μg a.i./L. This chronic endpoint, however, is actually higher than

the acute endpoint (Table A).  This inversion of expected results emphasizes the uncertainty of

testing near the saturation limit. Concentrations were confirmed in the chronic test but not the

acute test.  In the acute test technical grade simazine was used along with ethanol as a carrier

solvent; in the chronic test, an 80% formulated product was used and results adjusted for

concentration of a.i. Therefore, the most sensitive endpoint, the acute endpoint of EC50 = 1000

μg a.i./L, was adjusted with an ACR of 25 calculated from atrazine D. magna toxicity data

 

14 USEPA. 2007. Risks of Simazine Use to California Red‐legged Frog (Rana aurora draytonii). Environmental Fate

and Effects Division, Office of Pesticide Programs, Washington, D.C.  20460
17 

(3500/140 = 25; MRIDs 45087413 and 00024377 respectively). Applying this ACR to D. magna

acute data for simazine, a chronic endpoint of 40 μg a.i./L is calculated.  

A registrant submitted chronic mysid toxicity study (MRID 47984801, Guideline 850.1300) is

currently under review and will be considered for inclusion in the risk assessment. At this time

however, no acceptable chronic saltwater invertebrate toxicity data are available for simazine.  

Aquatic Plants:  

Guideline Tier II toxicity data for technical grade simazine is available for vascular duckweed

(Lemna gibba) and the following non‐vascular plants:  blue‐green algae (Anabaena flos‐aquae),

marine diatom (Skeletonema costatum and Phaeodactylum tricornutum), freshwater alga

(Pseudokirchneriella subcapitata), freshwater diatom (Navicula pelliculosa), marine algae

(Isochrysis galbana), and marine green algae (Chlorococcum sp. and Dunaliella tertiolecta).

Aquatic vascular plant endpoints from the Tier II Lemna study suggested that frond number was

the most sensitive endpoint (IC50 = 140 μg/L; NOAEC = 54; LOAEC = 110 μg/L). The Tier II results

indicate that freshwater blue‐green algae (Anabaena) is the most sensitive non‐vascular plant

to simazine (IC50 = 36 μg/L, IC05 = 5.4 μg/L; MRID 42662401) based on reduction in growth rates

observed by day 5.  In addition, a 28% reduction in cell density was observed at the lowest test

concentration of 20 μg/L.  

Freshwater Aquatic Field/Mesocosm Studies:  

A number of freshwater microcosm, mesocosm, and field studies are available for simazine,

although the lowest concentration of simazine tested in these studies was 1,000 μg/L, well

above environmentally relevant concentrations (summarized in USEPA 200715). Therefore, the

available field study data are inadequate to determine whether simazine applications to aquatic

habitats or runoff from terrestrial uses resulting in water concentrations below 1,000 μg/L

result in adverse effects to the aquatic community structure, productivity or function.

Prior to the risk assessment, a review of open literature for available mesocosm and microcosm

studies will be completed, and a determination made as to the appropriateness of their use in

the risk characterization.  The criteria for evaluating the cosm studies will be based upon those

already established for atrazine (http://www.regulations.gov/#!docketDetail;D=EPA‐HQ‐OPP‐

2003‐0367).

 

 

15 USEPA. 2007. Risks of Simazine Use to California Red‐legged Frog (Rana aurora draytonii). Environmental Fate

and Effects Division, Office of Pesticide Programs, Washington, D.C.  20460
18 

Table 4. Summary of the Most Sensitive Endpoints from Terrestrial Animal Toxicity Studies for

Simazine

Species Toxicity Value Used in

Risk Assessment

Citation

MRID#

Comment

Mallard Duck

Anas

platyrhynchos

LD50 = >4,640 mg

a.i./kg‐bw

000727‐98

(Fink, 1976)

Supplemental: No mortality at the highest

test concentration; however, reduced

reaction to external stimuli, wing droop, and

depression were observed at concentrations

as low as 1,000 mg a.i./kg‐bw one hour after

dosing.  

Mallard Duck

Anas

platyrhynchos

LC50 = >5,000 mg

a.i./kg‐diet

000229‐23

(Hill et al., 1975)

Acceptable: No mortality at the highest test

concentration

Northern

Bobwhite Quail

(Colinus

virginianus)

NOAEC = 100 mg a.i./kg

LOAEC = 500 mg a.i./kg

001631‐34

(Beavers, 1986)

Acceptable: Reduction in number of eggs

laid, viable embryos, live embryos,

hatchlings, and 14‐day old chick survivors at

500 mg a.i./kg

Laboratory rat

Rattus

norvegicus

Simazine LD50 = >5,000

mg a.i./kg‐bw

001488‐97

(Rosenfeld,

1985)

Acceptable: At 5,000 mg a.i./kg‐bw, 3/10

animals died

Laboratory rat

Rattus

norvegicus

NOAEC = 10 mg a.i./kg

LOAEC = 100 mg a.i./kg

418036‐01

(Epstein et al.,

1991)

Acceptable: Reduction in body weight gain

Honey bee acute

contact

LD50 = >96.7 μg a.i./bee 000369‐35

(Atkins et al.,

1975)

Acceptable: 6.5% mortality in the 96.7 μg

a.i./bee treatment group

Birds:  

Simazine is classified as practically non‐toxic to birds on an acute exposure basis. Subacute

avian dietary toxicity values for the technical grade and an 80% formulation indicate that

simazine is practically non‐toxic to birds.  

The available avian reproductive studies determined NOAECs 100 mg a.i./kg (MRID 001631‐34)

and 150 mg a.i./kg (MRID 435769‐01), based on the reduction in the number of eggs laid, viable

embryos, live embryos, hatchlings, and 14‐day old chick survivors.  

Mammals:  

Rats exposed to technical grade simazine showed no mortality at the highest doses tested

(Appendix A). The corresponding LD50 value for the TGAI is >5,000 mg/kg‐bw, suggesting

technical grade simazine is practically non‐toxic (MRID 001488‐97) to mammals on an acute

basis. Although a definitive LC50 was not established in the study, mortality was noted. In order

to gain a better understanding of how the EECs for the maximum proposed simazine
19 

application rate relate to the toxicity data currently available for mammals, the TREX model is

used to calculate the ratio of the EEC and toxicity endpoint.  In this exercise the acute ratios are

> 0.1. Although the highest dose tested is above the maximum expected exposure level, the

study indicates that there is a risk of mortality to non‐target mammals from the use of this

pesticide. Therefore, based on the available data the risk to federally listed species from the use

of simazine is an uncertainty.  

Acute mammalian oral toxicity data are also available for one degradate of simazine, DIA

(MRID 430123‐01). In this study both the female and male LD50 values for the degradate  

showed that the degradate appears to be more toxic to laboratory rats than technical grade

values for the parent simazine with respective values of 810 mg/kg for the female and 2,290

mg/kg for the male. The combined LD50 value for males and females is 1,240 mg/kg.

Reproductive and developmental mammalian toxicity studies provide adequate toxicity data on

chronic developmental and reproductive effects of simazine (USEPA 200716).  Chronic studies

using laboratory rats show consistent reductions in adult body weight gain and adult body

weight at simazine concentrations of 100 mg/kg‐diet.  The corresponding NOAEC value for

these studies is 10 mg/kg‐diet (MRIDs 418036‐01 and 406144‐05).  In addition, reproductive

effects including increased abortions, reduced fetal weight, and increased skeletal variations

were observed in New Zealand white rabbits at a concentration of 200 mg/kg/day, with a

corresponding NOAEL value of 75 mg/kg/day (MRID 001614‐07).  

Terrestrial Invertebrates:  

The use of simazine may result in exposure to non‐target insects, such as the honey bee. The

results of acute contact toxicity testing of simazine on the honey bee (Apis mellifera) show that

by 48 hours in the contact test (MRID 000369‐35), 6.5% mortality was observed in the 96.7

μg/bee treatment group; therefore, the LD50 value for the contact test is >96.7 μg/bee.  As a

result, simazine is categorized as practically non‐toxic to honeybees on an acute contact basis.   

Three open literature studies on simazine effects to non‐target insects including earthworms

and beetles were located and are summarized in USEPA 200717.  The results of two earthworm

studies (Martin, 1982: ECOTOX #58170; Lydy and Linck, 2003; ECOTOX #71459) showed no

adverse effects to mortality and growth, following 96‐hours of exposure at 10 ug/cm2 and 7

days of exposure at 100 ppm, the highest simazine concentrations tested. Samsoe‐Peterson

(1987; ECOTOX # 70278) evaluated the effects of Gesatop 50‐WP (50% simazine) on the rove

beetle, Aleochara bileneata.  Following 5‐days of exposure, no mortality or reduction in egg

production were observed in the simazine‐treated adult female beetles at an application rate of

 

16 USEPA. 2007. Risks of Simazine Use to California Red‐legged Frog (Rana aurora draytonii). Environmental Fate

and Effects Division, Office of Pesticide Programs, Washington, D.C.  20460 17 USEPA. 2007. Risks of Simazine Use to California Red‐legged Frog (Rana aurora draytonii). Environmental Fate

and Effects Division, Office of Pesticide Programs, Washington, D.C.  20460
20 

600 L/ha. According to the standard used by the International Organization of Biological Control

(IOBC) working group “Pesticides and Beneficial Organisms”, simazine was classified as

“harmless” to the rove beetle.   

Terrestrial Plants:

Plant toxicity data from both registrant‐submitted studies and studies in the scientific literature

were reviewed for this assessment (USEPA 2007).  Based on the results of the tests, it appears

that seedlings are more sensitive to simazine via soil/root uptake exposure than emerged

plants via foliar routes of exposure.  However, all tested plants, with the exception of corn,

exhibited adverse effects in both the seedling emergence and vegetative vigor toxicity tests,

following exposure to Princep 4L at 4 lb a.i./A.  The most sensitive endpoints resulting from the

Tier II seedling emergence and vegetative vigor toxicity tests on non‐target plants are

summarized below in Table 5. The full results are summarized in USEPA 2007.   

Table 5. Terrestrial Tier II Plant Seedling Emergence (MRID 42634603) and Vegetative Vigor Toxicity

Data (MRID 42634604).

Crop Type of Study

Species

NOAEC

[IC05]]

(lb a.i./A)

IC25

(lb a.i./A)

Most sensitive

parameter

Seedling Emergence

Monocot Onion 0.049

[0.0017] 0.02 Shoot Height

Dicot Lettuce 0.0018   0.009 Dry weight

Vegetative Vigor

Monocot Oat 0.016 0.030 Dry weight

Dicot Lettuce 0.016 0.028 Dry weight

4.2 Simazine Degradates

The degradates of simazine have been identified based on environmental fate studies. The two

major degradates are HS and DIA. As described above, there is evidence that DIA is more

acutely toxic than simazine to the laboratory rat. The endpoint for DIA will be used to evaluate

the risk to terrestrial mammals from the exposure to DIA. The remaining registrant‐submitted

data available for simazine terrestrial or aquatic degradates suggests that the degradates are

either as toxic or much less toxic than the parent.  

If available, observed terrestrial and acute toxicity endpoints for degradates of other triazines

that are closely related (i.e., have similar structures) to simazine degradates will be evaluated

for use in the risk assessment.
21 

4.3 Review of Incident Databases

A review of the Ecological Incident Information System (EIIS) database for ecological incidents

involving simazine was completed on January 25, 2013.  The results of this review for terrestrial

animal, plant, and aquatic animal incidents are discussed below in Sections 4.3.1 through 4.3.3,

respectively. The Aggregate Incident Summary report in IDS shows six simazine related

incidents, including two involving plant damage; and the others were single reports involving

moderate property damage, minor to moderate effects on domestic animals, fatal domestic

animal event, and one unspecified human event. The Avian Monitoring System (AIMS) is a

database administered by the American Bird Conservancy that contains publicly available data

on reported avian incidents involving pesticides.  Many of the incidents listed in this database

are also in the EIIS.   

4.3.1 Terrestrial Incidents

Only three simazine incidents have been reported involving terrestrial animals, two with

an “unlikely” certainty index and one “probable.”  In the incident with a certainty index of

“probable,” which occurred on June 26, 1998, five Canada geese were found dead in a corn

field in Rockingham County, Virginia, following spray application of Princep 4L (#I008168‐001).  

Soil and vegetative samples were collected along the bank near the creek in which the dead

geese were found.  Substantial concentrations of simazine and atrazine were found in the

samples.  Simazine detections ranged from 0.16 to 2.3 ppm in soil and 8.5 to 20.5 ppm in

foliage.   

4.3.2 Plant Incidents

Four simazine incidents have been reported for terrestrial plants, with two rated as being

“unlikely” a result of simazine.  In one incident, water from a simazine‐treated swimming pool

affected a section of lawn grass.  The certainty index for the lawn incident (# I003567‐001) is

“highly probable.”  Another incident report from New York, was a Syngenta 6(a)2 submission

regarding an allegation that the spraying of three herbicide formulations (a.i. included were

atrazine, simazine and primisulfuron‐methyl) caused loss of milk production and loss of corn

and hay production. The treatment site nor the magnitude of the incident were given, neither

was the magnitude or any analysis (IO16790‐007, September 20, 2005). The certainty index for

the incident involving simazine is listed as “probable.”

4.3.3 Aquatic Incidents

Ten freshwater aquatic incidents involving fish kills have been reported for simazine between

the years of 1976 and 2004.  Seven incidents have a certainty index of “highly probable” or

“probable,” and the other three have certainty indices of “possible” and “unlikely.”  One

incident resulted from runoff into a lake due to a valve failure in a chemical application hose

that was dispensing glyphosate and simazine to golf course turf. The incident resulted in the

death of 6 unknown species of fish.  Six incidents resulted from treatment of a lake, pond, or
22 

lagoon; two incidents were associated with simazine use on corn and from simazine use along

railroad tracks; one was due to a spill from golf course use, and the treatment site for the other

incident was not reported.  In a number of the incidents involving direct application of simazine

to lakes, ponds, and lagoons, the legality of use was listed as “misuse” or “undetermined.”  For

those incidents where the legality of use is reported as “registered use,” the volume of the

water bodies is not provided; therefore, it is unclear whether simazine was applied in

accordance with its intended use.  The six incidents involving direct application of simazine to

water all occurred prior to 1996, when label language was clarified to restrict direct applications

to ornamental ponds and aquaria.  It is important to note that in a number of the incidents

involving direct application of simazine to water, low dissolved oxygen, caused by decaying

aquatic vegetation, is attributed as an indirect effect related to the fish kills.   The certainty

index associated with the remaining three incidents (those resulting from use on corn, railroad

tracks, and an unspecified treatment site) was reported as “unlikely.”  

Of the ten reported incidents, three were reported in California, two were reported in

Nebraska, two were reported in South Carolina, and one was reported in Michigan, Oklahoma,

and in Tennessee. Fish species listed in these kills include smelt, bullheads, stickleback, striped

bass, bluegills, channel catfish, croaker, menhaden, mullet, northern pike, pinfish, yellow perch,

sea trout, black bullhead, and fathead minnows.   

The total number of actual incidents associated with the use of simazine may be higher than

what is reported to the Agency.  Incidents may go unreported since effects may not be

immediately apparent and/or readily attributed to the use of a chemical.

5. Exposure Pathways of Concern

For terrestrial vertebrates, the major routes of exposure to simazine is considered to be via

contact exposure and dietary ingestion of food items such as plants and/or animals that have

simazine residues as a result of direct application, spray drift, and/or runoff.  Exposure to

terrestrial vertebrates through inhalation is considered unlikely given simazine’s low vapor

pressure; a more quantitative analysis of risk through inhalation exposure via EFED’s Screening

Tool for Inhalation Risk (STIR v. 1.0) is not applicable because most of the avian endpoints and

the lowest rat inhalation endpoint are non‐definitive (LC50 > 1.7 mg/L; MRID 00148899).

However, when these endpoints are considered as definitive endpoints the exposure is

determined to be not likely significant at the highest labeled application rates for mammals,

and potentially significant for birds (Appendix C). The avian risk through inhalation is an

overestimation due to the non‐definitive endpoints and is not expected to lead to RQs

exceeding LOCs. EFED’s Screening Imbibition Program (SIP v. 1.0) suggests no concern for risk to

birds and mammals from acute and chronic exposure through the consumption of drinking

water with simazine residues (Appendix B).

For terrestrial invertebrates, the major routes of exposure to simazine are considered to be

direct contact as a result of direct application and spray drift and dietary ingestion of plants,
23 

animals, and/or soil that have simazine residues as a result of direct application, spray drift, and

runoff.   

For aquatic animal species, the major route of exposure to simazine is considered to be uptake

via the respiratory surface (gills) or the integument from surface water/sediment that has

simazine residues as a result of spray drift and/or runoff.

For terrestrial (upland and semi‐aquatic) non‐target plants, the major routes of exposure to

simazine are considered to be direct contact as a result of direct application and spray drift and

root uptake via soil contaminated via spray drift and runoff.

For aquatic plants, the major routes of exposure to simazine are considered to be uptake from

surface water/sediment containing simazine residues as a result of spray drift and/or runoff.

6. Analysis Plan

6.1 Stressors of Concern

The stressors of concern for terrestrial organisms are parent simazine and DIA.  The stressor of

concern for aquatic organisms is parent simazine alone.  The data indicate that the toxicity of

the major degradates of simazine to aquatic organisms is equal or less than that of the parent.  

Furthermore, the concentrations of the degradates are unlikely to be greater than the parent.

Therefore, any potential risk posed by degradates is expected to be inconsequential in

comparison to the parent.

6.2 Measures of Exposure  

To estimate risks to aquatic and terrestrial organisms from exposure to simazine, all exposure

modeling and resulting risk conclusions will be made based on maximum application rates,

application methods, and any mitigation measures  indicated on the label or formally agreed to

by registrants prior to the conduct of the risk assessments.  Models that will be used to predict

estimated environmental concentrations (EECs) of simazine are discussed on OPP’s model

website18.  These models include: PRZM (Pesticide Root Zone Model) and EXAMS (EXposure

Analysis Modeling System), PRZM‐groundwater (PRZM‐GW), T‐REX, and TerrPlant.

6.3 Measure of Effects

Ecological effects data are used as measures of direct and indirect effects to biological

receptors. Data are typically obtained from registrant‐submitted studies or from literature

 

18 http://www.epa.gov/pesticides/science/models_db.htm
24 

studies identified by ECOTOX. The ECOTOX database provides more ecological effects data in an

attempt to bridge existing data gaps. ECOTOX is a source for locating single chemical toxicity

data and potential chemical mixture toxicity data for aquatic life, terrestrial plants, and

wildlife. ECOTOX was created and is maintained by the USEPA, Office of Research and

Development, and the National Health and Environmental Effects Research Laboratory's Mid‐

Continent Ecology Division.

6.4 Integration of Exposure and Effects

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

potential ecological risk from the use of pesticides and the likelihood of direct and indirect

effects to non‐target organisms in aquatic and terrestrial habitats. For the assessment of risks,

the risk quotient (RQ) method is used to compare exposure and measured toxicity values. EECs

are divided by acute and chronic toxicity values. The resulting RQs are then compared to the

Agency’s Levels of Concern (LOCs). These criteria will be used to indicate when simazine use, as

directed on the label, has the potential to cause adverse direct or indirect effects to non‐target

organisms. In addition, incident data from the EIIS, IDS, and AIMS will be considered as part of

the risk characterization.

6.5 Drinking Water Assessment

A new drinking water assessment will be conducted to support future human health dietary risk

assessments of simazine and will consider all currently registered uses. The new drinking water

assessment will incorporate model estimates as well as available monitoring data of simazine

and any transformation products of toxicological concern that might be identified by the Health

Effects Division in surface water and groundwater.  The potential toxicity of simazine

transformation products will be considered in the drinking water assessment conducted during

the Registration Review process.   

6.6 Endocrine Disruptor Screening Program (EDSP)  

As required by FIFRA and FFDCA, EPA reviews numerous studies to assess potential adverse

outcomes from exposure to chemicals. Collectively, these studies include acute, subchronic and

chronic toxicity, including assessments of carcinogenicity, neurotoxicity, developmental,

reproductive, and general or systemic toxicity. These studies include endpoints which may be

susceptible to endocrine influence, including effects on endocrine target organ histopathology,

organ weights, estrus cyclicity, sexual maturation, fertility, pregnancy rates, reproductive loss,

and sex ratios in offspring. For ecological hazard assessments, EPA evaluates acute tests and

chronic studies that assess growth, developmental and reproductive effects in different

taxonomic groups. As part of its reregistration decision, EPA reviewed these data and selected

the most sensitive endpoints for relevant risk assessment scenarios from the existing hazard
25 

database. However, as required by FFDCA section 408(p), simazine is subject to the endocrine

screening part of the Endocrine Disruptor Screening Program (EDSP).  

EPA has developed the EDSP to determine whether certain substances (including pesticide

active and other ingredients) may have an effect in humans or wildlife similar to an effect

produced by a “naturally occurring estrogen, or other such endocrine effects as the

Administrator may designate.”  The EDSP employs a two‐tiered approach to making the

statutorily required determinations. Tier 1 consists of a battery of 11 screening assays to

identify the potential of a chemical substance to interact with the estrogen, androgen, or

thyroid (E, A, or T) hormonal systems. Chemicals that go through Tier 1 screening and are found

to have the potential to interact with E, A, or T hormonal systems will proceed to the next stage

of the EDSP where EPA will determine which, if any, of the Tier 2 tests are necessary based on

the available data. Tier 2 testing is designed to identify any adverse endocrine‐related effects

caused by the substance, and establish a dose‐response relationship between the dose and the

E, A, or T effect.  

Under FFDCA section 408(p), the Agency must screen all pesticide chemicals. Between October

2009 and February 2010, EPA issued test orders/data call‐ins for the first group of 67 chemicals,

which contains 58 pesticide active ingredients and 9 inert ingredients. Simazine was included on

that list and has been issued an order to conduct the Tier 1 testing. Once all required Tier 1 and

Tier 2 data have been received and reviewed, the endpoints and safety factors used for risk

assessment purposes will be examined and a new risk assessment performed if necessary. For

further information on the status of the EDSP, the policies and procedures, the list of 67

chemicals, future lists, the test guidelines and the Tier 1 screening battery, please visit our

website:  http://www.epa.gov/endo/.  

6.7 Endangered Species Assessments

Consistent with the Agency’s responsibility under the Endangered Species Act (ESA), the Agency

will evaluate exposure and potential risks to federally listed threatened and/or endangered

(listed) species from registered uses of pesticides in registration review.

7. Preliminary Identification of Data Gaps  

The following sections identify the available data that will be considered for the upcoming

ecological risk assessment in support of the Registration Review of the registered uses of

simazine.   

Environmental Fate and Transport

Table 6 identifies the environmental fate studies submitted by the registrant that will be

considered to support the registration review exposure assessments. The database for
26 

environmental fate and transport for simazine is sufficient for risk assessment. No additional

data are needed at this time.

Table 6.  Submitted Environmental Fate Data for Chemical Simazine

OCSPP

Guideline

Data

Requirement

Submitted

Studies

(MRID)

Study

Classifications

Are data

needed to

conduct risk

assessment?

Comments

835.2120 Hydrolysis 27856 Acceptable   no

835.2240 Aqueous

photolysis 42503708 Acceptable no   

835.2410 Soil photolysis 42739101 Acceptable no   

835.4100 Aerobic soil

metabolism

158638 Supplemental

no   

43004501 Supplemental   

835.4200 Anaerobic soil

metabolism   27857 Supplemental no

The 51‐day anaerobic soil

metabolism study included

substantial unextractable

residues, which inhibited half‐

life estimation.  EPA intends to

assume that simazine is stable

to anaerobic soil metabolism in

the ecological risk assessment

and drinking water assessment

for registration review, as this

assumption is not expected to

substantially change risk

assessment results.

835.4300 Aerobic aquatic

metabolism 43004502 Acceptable no   

835.4400

Anaerobic

aquatic

metabolism

40614411 Acceptable no

  

835.1230

835.1240

Adsorption/

desorption and

leaching

41442903   Acceptable

no   

41257903   Acceptable   

835.1410 Volatility –

laboratory 24331 Supplemental no

With low vapor pressure (6.1 x

10‐9 mm Hg at 20°C) and low

Henry's Law Constant (3.2 x 10‐

10 atm m3/mol at 25°C),

volatilization losses of simazine

from soil and water systems are

expected to be insignificant.  

835.6100 Terrestrial field

dissipation  

40634202 Supplemental

no   

27863 Supplemental   
27 

OCSPP

Guideline

Data

Requirement

Submitted

Studies

(MRID)

Study

Classifications

Are data

needed to

conduct risk

assessment?

Comments

850.6100 Analytical

method in soil

None

identified

for above

TFD studies

n/a   yes

A current analytical method for

soil is needed.  

835.6200 Aquatic field

dissipation

27829 Supplemental

no

  

40614420 Supplemental   

40614422 Supplemental   

850.6100 Analytical

method in water

  None

identified

for above

AFD studies

n/a

  

850.1730 Fish

bioconcentration 43668   Supplemental no

860.1340

Residue

Analytical

Method

47629802 Acceptable no

This MRID is the analytical

method used for measuring

residues in the Simazine and

Atrazine drinking water

Monitoring Programs.  Prior

methods have been submitted

but are no longer used.

   
28 

Effects

The ecological effects database is incomplete for the risk assessment; however, in the absence

of acceptable studies for simazine, data available from other triazine herbicides will be

evaluated for use in the simazine risk assessment. Table 7 and Table 8 identify the ecological

effects studies, as well as study classifications and whether or not further data are needed in

order to support risk assessment.  

Table 7. Submitted Aquatic Ecological Effects Data for Simazine

OCSPP

Guideline

Data

Requirement

Submitted

Studies

(MRID)

Study

Classifications

Are data

needed to

conduct risk

assessment?

Comments

850.1010 Freshwater

invertebrate  

acute toxicity

45088221 Supplemental No

850.1025

850.1035

850.1045

850.1055  

Saltwater

invertebrate  

acute toxicity  

00043677 Supplemental No

42503703 Acceptable

00023331 Acceptable

850.1075 Freshwater fish

acute toxicity  

00023321 Acceptable No

00023322 Supplemental

00033309 Supplemental

00163135 Supplemental

00163136 Supplemental

00043668 Supplemental

40245701 Supplemental

850.1075 Saltwater fish

acute toxicity  

42503702 Supplemental No

850.1300 Freshwater

invertebrate  

life cycle  

No At this time no acceptable

chronic freshwater invertebrate

toxicity data are available for

simazine; however, an ACR will

be used for the risk assessment

in the absence of new data.
29 

OCSPP

Guideline

Data

Requirement

Submitted

Studies

(MRID)

Study

Classifications

Are data

needed to

conduct risk

assessment?

Comments

850.1350 Saltwater

invertebrates  

life cycle  

47984801 ‐ 

Pending

review

No – see

comment.

A registrant submitted chronic

mysid toxicity study (MRID

47984801) is currently under

review and will be considered

for inclusion in the risk

assessment.  

850.1400 Freshwater fish  

early‐life stage

none No No freshwater fish early life‐

stage tests using the TGAI are

available. Data from open

literature and other triazines will

be used in the absence of a

registrant submitted study.  

850.1400 Saltwater fish   

early‐life stage  

none No This study is not requested at

this time. Data from open

literature and other triazines will

be used in the absence of a  

registrant submitted study.

850.1500 Fish life cycle   00043676 No – see

comment.

The available data will only be

used qualitatively in the risk

assessment. Although data are

not currently available for risk

quantification, a study is not

requested at this time. Data

from open literature and other

triazines will be used in the

absence of a registrant

submitted study.

850.4400 Aquatic plant

growth:

Tier II vascular

plants

42503704 Acceptable No

850.4500 Aquatic Plant

Growth:

Tier II Algal

Toxicity

42503705 Acceptable No

42503706 Acceptable

42503707 Acceptable

42662401 Supplemental

850.4550 Aquatic Plant

Growth:

Tier II

Cyanobacteria

Toxicity

42662401 Supplemental No
30 

   
31 

Table 8. Submitted Terrestrial Ecological Effects Data for Simazine

OCSPP

Guideline Data Requirement

Submitted

Studies

(MRID)

Study

Classifications

Are data needed

for risk

assessment?

Comments

850.2100 Avian oral toxicity 00072798 Supplemental No Acute avian oral toxicity

studies using mallard duck,

chicken, and pigeon are

available.  Although data are

not available for a passerine

species, based on existing

information, it is not

expected that a passerine

study would add any

valuable information to the

avian risk assessment.  

00037750 Supplemental

00037751 Supplemental

850.2200 Avian dietary toxicity   00022923

(Japanese

Quail)

Supplemental No

00022923

(Bobwhite

Quail)

Acceptable

00022923

(Mallard

Duck)

Acceptable

00022923

(Ring‐

Necked

Pheasant)

Supplemental

00139393 Supplemental

00023318 Supplemental

00025436 Supplemental

00023319 Acceptable

850.2300 Avian reproduction 00163134 Acceptable No

43576901 Acceptable

00043678 Supplemental

850.3020 Honey bee acute contact

toxicity

00036935 Acceptable No

850.4100 Terrestrial plant toxicity:

Tier II seedling

emergence

42634603 Acceptable No

850.4150 Terrestrial plant toxicity:

Tier II vegetative vigor

42634604 Acceptable No
32 

Appendix A:  Simazine Degradation Products in Environmental Fate Studies

Table A‐1. CAS Numbers, Names, Formulas, and Structures of Simazine Degradates

CAS Number, Name,

Chemical Formula Structure Synonyms

1007‐28‐9

6‐Deisopropylatrazine

C5H8ClN5

Deisopropylatrazine

Deethylsimazine

CAET/CEAT/DIA/G‐28279/GS‐

28279

2599‐11‐3

Hydroxysimazine

C7H13N5O

OEET/HS/G‐30414/GS‐30414

3397‐62‐4

2‐Chloro‐4,6‐diamino‐s‐

triazine

C3H4ClN5

Diadealkylatrazine

Diaminochloro‐s‐triazine

CAAT/DACT/DDA/G‐28273/GS‐

28273
33 

CAS Number, Name,

Chemical Formula Structure Synonyms

7313‐54‐4

s‐Triazin‐2‐ol, 4‐amino‐6‐

(ethylamino)‐ (8CI)

C5H9N5O

Deisopropylhydroxyatrazine

Desethylhydroxysimazine

OEAT/OAET/DIHA/GS‐17792

645‐92‐1

Ammeline

C3H5N5O

OAAT/AAOT/GS‐17791

30360‐56‐6

2‐Amino‐4‐ethylamino‐6‐

methoxy‐s‐triazine

C6H11N5O

Debutylsecbumeton

MAET/GS‐31709/G‐31709

CAS number not found 2‐chloro‐4‐ethylamino‐6‐

hydroxyethylamino‐s‐triazine  

G‐28516
34 

CAS Number, Name,

Chemical Formula Structure Synonyms

CAS number not found o‐methyl hydroxysimazine

G‐30044
35 

Appendix B: SIP (v 1.0) Inputs and Results

The purpose of this model is to provide an upper bound estimate of exposure of birds and mammals to

pesticides through drinking water alone. This model is intended for use in problem formulation to determine

whether or not drinking water exposure alone is a potential pathway of concern. This does not aggregate

drinking water exposure with other exposure routes (i.e., diet, inhalation, dermal).

  

Assumptions:

  

SIP employs the following conservative assumptions to derive upper bound exposure estimates:

1) The chemical concentration in drinking water is at the solubility limit in water (at 25oC).

2) The assessed animals obtain 100% of their daily water needs through drinking water.

3) The daily water need is equivalent to the daily water flux rate as calculated by Nagy and Peterson (1988).

4) The body weight of the assessed bird is equivalent to the smallest generic bird modeled in T‐REX (i.e., 20 g).

This assumption results in the highest ratio of exposure to toxicity for the 3 assessed avian body weights of T‐

REX (i.e., 20, 100, 1000 g).

5) The body weight of the assessed mammal is equivalent to the largest generic mammal modeled in T‐REX (i.e.,

1000 g). This results in the highest ratio of exposure to toxicity for the 3 assessed mammalian body weights of T‐

REX (i.e., 15, 35, 1000 g).  

Table 1. Inputs      

Parameter Value   

Chemical name Simazine   

Solubility (in water at 25oC; mg/L) 5   

  

Mammalian LD50 (mg/kg‐bw) 5000   

Mammalian test species laboratory rat   

Body weight (g) of "other" mammalian species      

  

Mammalian NOAEL (mg/kg‐bw) 10   

Mammalian test species laboratory rat   

Body weight (g) of "other" mammalian species      

  

Avian LD50 (mg/kg‐bw) 4640   

Avian test species mallard duck   

Body weight (g) of "other" avian species      

Mineau scaling factor 1.15   

  

Mallard NOAEC (mg/kg‐diet) 0   

Bobwhite quail NOAEC (mg/kg‐diet) 100   

NOAEC (mg/kg‐diet) for other bird species      

Body weight (g) of other avian species      

NOAEC (mg/kg‐diet) for 2nd other bird species      

Body weight (g) of 2nd other avian species      

        

        

        
36 

Table 2. Mammalian Results      

Parameter      

Upper bound exposure (mg/kg‐bw)      

Adjusted toxicity value (mg/kg‐bw) Acute Chronic

Ratio of exposure to toxicity 0.8600 0.8600

Conclusion* 3845.8028 7.6916

   0.0002 0.1118

Table 3. Avian Results

Drinking water exposure

alone is NOT a potential

concern for mammals

Drinking water exposure

alone is NOT a potential

concern for mammals

Parameter      

Upper bound exposure (mg/kg‐bw)      

Adjusted toxicity value (mg/kg‐bw) Acute Chronic

Ratio of exposure to acute toxicity 4.0500 4.0500

Conclusion* 2409.2059 10.6298

   0.0017 0.3810

*Conclusion is for drinking water exposure

alone.  This does not combine all routes of

exposure.  Therefore, when aggregated with

other routes (i.e., diet, inhalation, dermal),

pesticide exposure through drinking water may

contribute to a total exposure that has potential

for effects to non‐target animals.

Drinking water exposure

alone is NOT a potential

concern for birds

Drinking water exposure

alone is NOT a potential

concern for birds

     
37 

Appendix C: STIR model results using maximum label rate.  

Input      

Application and Chemical Information      

Enter Chemical Name Simazine    

Enter Chemical Use Grapefruit    

Is the Application a Spray? (enter y or n) y    

If Spray What Type (enter ground or air) ground    

Enter Chemical Molecular Weight (g/mole) 201.66    

Enter Chemical Vapor Pressure (mmHg) 6.10E‐09   

Enter Application Rate (lb a.i./acre) 8    

        

Toxicity Properties      

Bird      

Enter Lowest Bird Oral LD50 (mg/kg bw) 4600    

Enter Mineau Scaling Factor 1.15    

Enter Tested Bird Weight (kg) 1.58    

Mammal      

Enter Lowest Rat Oral LD50 (mg/kg bw) 5000    

Enter Lowest Rat Inhalation LC50 (mg/L) 1.7    

Duration of Rat Inhalation Study (hrs) 4   

Enter Rat Weight (kg) 0.35    

        

Output      

Results Avian (0.020 kg )      

Maximum Vapor Concentration in Air at Saturation (mg/m3) 6.62E‐05    

Maximum 1‐hour Vapor Inhalation Dose (mg/kg) 8.32E‐06    

Adjusted Inhalation  LD50   6.28E+00    

Ratio of Vapor Dose to Adjusted Inhalation LD50 1.32E‐06 Exposure not Likely Significant

Maximum Post‐treatment Spray Inhalation Dose (mg/kg) 8.45E‐01    

Ratio of Droplet Inhalation Dose to Adjusted Inhalation LD50   1.35E‐01 Proceed to Refinements

        

Results Mammalian (0.015 kg )      

Maximum Vapor Concentration in Air at Saturation (mg/m3) 6.62E‐05    

Maximum 1‐hour Vapor Inhalation Dose (mg/kg) 1.05E‐05    

Adjusted Inhalation  LD50   1.01E+02    

Ratio of Vapor Dose to Adjusted Inhalation LD50 1.03E‐07 Exposure not Likely Significant

Maximum Post‐treatment Spray Inhalation Dose (mg/kg) 1.06E+00    

Ratio of Droplet Inhalation Dose to Adjusted Inhalation LD50   1.05E‐02 Exposure not Likely Significant
38 

Appendix D. Simazine Registered Products included in the Registration Review

PRODUCT NAME Ai% Site Desc REG#

ALGICLEAR 0.9 Ornamental Ponds/Aquaria 9712‐8

CLEAN CROP

SIMAZINE 4L

FLOWABLE

HERBICIDE

42.8 Alfalfa WA900040

Brussels Sprouts, Cabbage WA900005

DREXEL SIMAZAT

4L HERBICIDE

21.41 Christmas Tree Plantations, Corn, Field, Corn, Sweet 19713‐171

DREXEL SIMAZAT

90DF

45 Christmas Tree Plantations, Corn, Field, Corn, Sweet 19713‐553

DREXEL SIMAZINE

4F

42.1 Almond, Apple, Avocado, Blueberry, Caneberries, Cherry,

Christmas Tree Plantations, Corn, Field, Corn, Sweet,

Cranberry, Filbert (Hazelnut), Golf Course Turf, Grapefruit,

Grapes, Lemon, Macadamia Nut (Bushnut), Nectarine,

Nursery Stock, Olive, Orange, Ornamental Lawns And Turf,

Ornamental Sod Farm (Turf), Peach, Pear, Pecan, Plum,

Residential Lawns, Shelterbelt Plantings, Strawberry, Walnut

(English/Black)

19713‐273

DREXEL SIMAZINE

4L

42.1 Alfalfa WA090015

Brussels Sprouts, Cabbage WA090016

Almond, Apple, Avocado, Blueberry, Caneberries, Cherry,

Christmas Tree Plantations, Corn, Field, Corn, Sweet,

Cranberry, Filbert (Hazelnut), Golf Course Turf, Grapefruit,

Grapes, Lemon, Macadamia Nut (Bushnut), Nectarine,

Nursery Stock, Olive, Orange, Ornamental Lawns And Turf,

Ornamental Sod Farm (Turf), Peach, Pear, Pecan, Plum,

Residential Lawns, Shelterbelt Plantings, Strawberry, Walnut

(English/Black)

19713‐60

OXON ITALIA SIM‐

TROL 4L SIMAZINE

FLOWABLE

HERBICIDE

42.8 Almond, Apple, Avocado, Blueberry, Caneberries, Cherry,

Christmas Tree Plantations, Corn, Field, Cranberry, Filbert

(Hazelnut), Golf Course Turf, Grapefruit, Grapes, Lemon,

Macadamia Nut (Bushnut), Nectarine, Nursery Stock, Olive,

Orange, Ornamental Lawns And Turf, Ornamental Sod Farm

(Turf), Peach, Pear, Pecan, Plum, Shelterbelt Plantings,

Strawberry, Walnut (English/Black)

35915‐11

PRINCEP 4L 41.9 Shelterbelt Plantings SD040005

SD090009

Citrus CA050004

Almond, Apple, Avocado, Blueberry, Caneberries, Cherry,

Christmas Tree Plantations, Corn, Field, Corn, Sweet, Filbert

(Hazelnut), Golf Course Turf, Grapefruit, Grapes, Lemon,

Macadamia Nut (Bushnut), Nectarine, Nursery Stock, Olive,

Orange, Ornamental Lawns And Turf, Ornamental Sod Farm

(Turf), Peach, Pear, Pecan, Plum, Shelterbelt Plantings,

Strawberry, Walnut (English/Black)

100‐526

PRINCEP CALIBER

90  

90 Cherry OR080038

Black Walnut (Forest) Oak (Forest/Shelterbelt) Persimmon MD980002
39 

PRODUCT NAME Ai% Site Desc REG#

Almond, Apple, Avocado, Blueberry, Caneberries, Cherry,

Christmas Tree Plantations, Corn, Field, Corn, Sweet, Filbert

(Hazelnut), Golf Course Turf, Grapefruit, Grapes, Lemon,

Macadamia Nut (Bushnut), Nectarine, Nursery Stock, Olive,

Orange, Ornamental Lawns And Turf, Ornamental Sod Farm

(Turf), Peach, Pear, Pecan, Plum, Shelterbelt Plantings,

Strawberry, Walnut (English/Black),  

100‐603

Shelterbelt Plantings SD090010

SIMAZINE 4L,   41.9 Alfalfa WA090005

Almond, Apple, Avocado, Blueberry, Caneberries, Cherry,

Christmas Tree Plantations, Corn, Field, Corn, Sweet, Filbert

(Hazelnut), Golf Course Turf, Grapefruit, Grapes, Lemon,

Macadamia Nut (Bushnut), Nectarine, Nursery Stock, Olive,

Orange, Ornamental Lawns And Turf, Ornamental Sod Farm

(Turf), Peach, Pear, Pecan, Plum, Shelterbelt Plantings,

Strawberry, Walnut (English/Black)

9779‐296

42.8,   Broccoli, Brussels Sprouts, Cabbage, Kale, Kohlrabi OR050017

SIMAZINE 4L

FLOWABLE

HERBICIDE

41.9,   Almond, Apple, Avocado, Blueberry, Caneberries, Cherry,

Christmas Tree Plantations, Corn, Field, Corn, Sweet,

Cranberry, Filbert (Hazelnut), Grapefruit, Grapes, Lemon,

Macadamia Nut (Bushnut), Nectarine, Olive, Orange, Peach,

Pear, Pecan, Plum, Shelterbelt Plantings, Strawberry,

Walnut (English/Black)

34704‐687

SIMAZINE 90

HERBICIDE,  

90,   Almond, Apple, Avocado, Blueberry, Caneberries, Cherry,

Christmas Tree Plantations, Corn, Field, Corn, Sweet,

Cranberry, Filbert (Hazelnut), Grapefruit, Grapes, Lemon,

Macadamia Nut (Bushnut), Nectarine, Olive, Orange, Peach,

Pear, Pecan, Plum, Shelterbelt Plantings, Strawberry,

Walnut (English/Black)

34704‐916

SIMAZINE 90 WDG 90 Almond, Apple, Avocado, Blueberry, Caneberries, Cherry,

Christmas Tree Plantations, Corn, Field, Corn, Sweet,

Cranberry, Filbert (Hazelnut), Grapefruit, Grapes, Lemon,

Macadamia Nut (Bushnut), Nectarine, Olive, Orange, Peach,

Pear, Pecan, Plum, Shelterbelt Plantings, Strawberry,

Walnut (English/Black)

34704‐686

SIMAZINE 90DF,   90,   Almond,  , Apple, , Avocado, , Blueberry, , Caneberries,  ,

Cherry,  , Christmas Tree Plantations,  , Corn, Field,  , Corn,

Sweet,  , Cranberry,  , Filbert (Hazelnut),  , Golf Course Turf,

, Grapefruit,  , Grapes,  , Lemon,  , Macadamia Nut

(Bushnut),  , Nectarine, Nursery Stock,  , Olive,  , Orange,  ,

Ornamental Lawns And Turf,  , Ornamental Sod Farm (Turf),

, Peach,  , Pear,  , Pecan,  , Plum,  , Shelterbelt Plantings,  ,

Strawberry,  , Walnut (English/Black),   

19713‐252,

9779‐295

SIM‐TROL 9DF,   90,   Almond, Apple, Avocado, Black Walnut (Forest), Blueberry,

Caneberries, Cherry, Christmas Tree Plantations, Corn, Field,

Corn, Sweet, Cranberry, Filbert (Hazelnut), Golf Course Turf,

Grapefruit, Grapes, Lemon, Loblolly Pine (Forest),

Macadamia Nut (Bushnut), Nectarine, Nursery Stock, Olive,

Orange, Ornamental Lawns And Turf, Ornamental Sod Farm

(Turf), Peach, Pear, Pecan, Plum, Shelterbelt Plantings, Slash

Pine (Forest), Strawberry, Walnut (English/Black), White

35915‐12
40 

PRODUCT NAME Ai% Site Desc REG#

Pines (Forest)

SMZ 4L 41.9 Almond, Apple, Avocado, Blueberry, Caneberries, Cherry,

Christmas Tree Plantations, Corn, Field, Corn, Sweet,

Cranberry, Filbert (Hazelnut), Grapefruit, Grapes, Lemon,

Macadamia Nut (Bushnut), Nectarine, Olive, Orange, Peach,

Pear, Pecan, Plum, Shelterbelt Plantings, Strawberry,

Walnut (English/Black)

34704‐913

UCPA SIMAZINE 4L,   42.1,   Almond, Apple, Avocado, Blueberry, Caneberries, Cherry,

Christmas Tree Plantations, Corn, Field, Corn, Sweet,

Cranberry, Filbert (Hazelnut), Golf Course Turf, Grapefruit,

Grapes, Lemon, Macadamia Nut (Bushnut), Nectarine,

Nursery Stock, Olive, Orange, Ornamental Lawns And Turf,

Ornamental Sod Farm (Turf), Peach, Pear, Pecan, Plum,

Residential Lawns, Shelterbelt Plantings, Strawberry, Walnut

(English/Black)

72693‐7

UCPA SIMAZINE

90DF

90 Almond, Apple, Avocado, Blueberry, Caneberries, Cherry,

Christmas Tree Plantations, Corn, Field, Corn, Sweet,

Cranberry, Filbert (Hazelnut), Golf Course Turf, Grapefruit,

Grapes, Lemon, Macadamia Nut (Bushnut), Nectarine,

Nursery Stock, Olive, Orange, Ornamental Lawns And Turf,

Ornamental Sod Farm (Turf), Peach, Pear, Pecan, Plum,

Shelterbelt Plantings, Strawberry, Walnut (English/Black)

72693‐8

UPI SIMAZINE 4L 42.8 Almond, Apple, Avocado, Blueberry, Caneberries, Cherry,

Christmas Tree Plantations, Corn, Field, Corn, Sweet,

Cranberry, Filbert (Hazelnut), Golf Course Turf, Grapefruit,

Grapes, Lemon, Macadamia Nut (Bushnut), Nectarine,

Nursery Stock, Olive, Orange, Ornamental Lawns And Turf,

Ornamental Sod Farm (Turf), Peach, Pear, Pecan, Plum,

Shelterbelt Plantings, Strawberry, Walnut (English/Black)

70506‐232

UPI SIMAZINE 90DF

HERBICIDE

90 Almond, Apple, Avocado, Black Walnut (Forest), Blueberry,

Caneberries, Cherry, Christmas Tree Plantations, Corn, Field,

Corn, Sweet, Cranberry, Filbert (Hazelnut), Golf Course Turf,

Grapefruit, Grapes, Lemon, Loblolly Pine (Forest),

Macadamia Nut (Bushnut), Nectarine, Nursery Stock, Olive,

Orange, Ornamental Lawns And Turf, Ornamental Sod Farm

(Turf), Peach, Pear, Pecan, Plum, Shelterbelt Plantings, Slash

Pine (Forest), Strawberry, Walnut (English/Black), White

Pines (Forest)

70506‐233

   
41 

Appendix E: Labeled Uses and Rates to be used for the risk assessment

Site Desc Max

App

Rate  

(lbs

a.i./A)

Max

App

Rate/Ye

ar (lbs

a.i./A)

Max #

Apps

MRI Applicatio

n Method

Type

Applicatio

n Method

Equipmen

t

Application

Method

Timing

Reg# Geo Areas

ALFALFA 1.5922 NS 1 / yr NS Broadcast

.

Ground. Postharvest. WA090005 Washington

         Early spring. WA090005 Washington

   1.41582

4

NS 1 / yr NS Broadcast

.

Aircraft. Postharvest. WA900040 Washington

         Early spring. WA900040 Washington

   1.39266

8

NS 1 / yr NS Broadcast

.

Ground. Dormant. WA090015 Washington

BROCCOLI 7.07912 NS NS NS Broadcast

.

Ground. Late fall. OR050017 Oregon,Other (refer

to issues report)

BRUSSELS

SPROUTS

7.07912 NS NS NS Broadcast

.

Ground. Late fall. OR050017 Oregon,Other (refer

to issues report)

   0.7999 NS NS NS Broadcast

.

Ground. Fall. WA090016 Washington

         Early spring. WA090016 Washington

CABBAGE 7.07912 NS NS NS Broadcast

.

Ground. Late fall. OR050017 Oregon,Other (refer

to issues report)

   0.7999 NS NS NS Broadcast

.

Ground. Fall. WA090016 Washington

         Early spring. WA090016 Washington

CORN        

CORN, FIELD 2.0009 2.50112

5

NS NS Broadcast

.

Ground. Preemergence

.

35915‐11

         Chemigati

on.

Sprinkler

irrigation.

Preplant. 19713‐273

CORN, SWEET 2.0009 2.50112

5

NS NS Broadcast

.

Ground. Preemergence

.

70506‐232

         Chemigati

on.

Sprinkler

irrigation.

Preplant. 19713‐273

Berries/Fruit

Crops

      

BLUEBERRY 4.0018 4.0018 NS NS Band

treatment

.

Band

sprayer.

Spring. 35915‐11

         Fall. 35915‐11

         Broadcast

.

Ground. Spring. 35915‐11

         Fall. 35915‐11

         Spot

treatment

.

Ground. Spring. 35915‐11

         Fall. 35915‐11

         Chemigati

on.

Sprinkler

irrigation.

Spring. 19713‐273

         Fall. 19713‐273

         Spot

treatment

.

Ground. Spring. 19713‐273
42 

CANEBERRIES 4.0018 4.0018 NS NS Band

treatment

.

Band

sprayer.

Spring. 35915‐11

         Broadcast

.

Ground. Fall. 35915‐11

         Chemigati

on.

Sprinkler

irrigation.

Spring. 19713‐273

         Fall. 19713‐273

         Spot

treatment

.

Ground. Spring. 19713‐273

         Fall. 19713‐273

CRANBERRY 4.0018 4.0018 1 / yr NS Band

treatment

.

Band

sprayer.

Postharvest. 35915‐11 Massachusetts

         Broadcast

.

Ground. Postharvest. 35915‐11 Massachusetts

         Spot

treatment

.

Ground. Postharvest. 35915‐11 Massachusetts

         Chemigati

on.

Sprinkler

irrigation.

Postharvest. 19713‐273 Massachusetts

STRAWBERRY 1.00045 1.00045 1 / yr NS Band

treatment

.

Band

sprayer.

Renovation. 35915‐11 Washington,Oregon

         Fall. 35915‐11 Washington,Oregon

         Broadcast

.

Ground. Renovation. 35915‐11 Washington,Oregon

         Fall. 35915‐11 Washington,Oregon

         Spot

treatment

.

Ground. Renovation. 35915‐11 Washington,Oregon

         Fall. 35915‐11 Washington,Oregon

         Chemigati

on.

Sprinkler

irrigation.

Renovation. 19713‐273 Washington,Oregon

         Fall. 19713‐273 Washington,Oregon

Grapes        

GRAPES 4.0018 4.0018 1 / yr NS Band

treatment

.

Band

sprayer.

Postharvest. 35915‐11

         Broadcast

.

Ground. Postharvest. 35915‐11

         Spot

treatment

.

Ground. Postharvest. 35915‐11

         Chemigati

on.

Sprinkler

irrigation.

Postharvest. 19713‐273

Leafy Greens        

KALE 7.07912 NS NS NS Broadcast

.

Ground. Late fall. OR050017 Oregon,Other (refer

to issues report)

KOHLRABI 7.07912 NS NS NS Broadcast

.

Ground. Late fall. OR050017 Oregon,Other (refer

to issues report)

CITRUS        

CITRUS 3.99726 3.99726 NS NS Chemigati

on.

Sprinkler

irrigation.

Foliar. CA050004 Specific County

(refer to the issues

report),California

   1.99863 3.99726 NS NS Chemigati

on.

Sprinkler

irrigation.

Spring. CA050004 Specific County

(refer to the issues
43 

report),California

         Fall. CA050004 Specific County

(refer to the issues

report),California

GRAPEFRUIT 8.0036 8.0036 1 / yr NS Band

treatment

.

Band

sprayer.

Spring. 35915‐11 Florida

   4.0018 8.0036 2 / yr NS Broadcast

.

Ground. Spring. 35915‐11 Florida

         Chemigati

on.

Sprinkler

irrigation.

Spring. 19713‐273 Florida

   4.0018 NS NS Band

treatment

.

Band

sprayer.

Weed

preemergence

.

35915‐11 California,Texas

         Broadcast

.

Ground. Weed

preemergence

.

35915‐11 Texas,California

         Spot

treatment

.

Ground. Weed

preemergence

.

35915‐11 California,Texas

         Chemigati

on.

Sprinkler

irrigation.

Weed

preemergence

.

19713‐273 California,Texas

         Spot

treatment

.

Ground. Weed

preemergence

.

19713‐273 Texas,California

LEMON 4.0018 4.0018 NS NS Band

treatment

.

Band

sprayer.

Weed

preemergence

.

35915‐11 California

         Broadcast

.

Ground. Weed

preemergence

.

35915‐11 California

         Spot

treatment

.

Ground. Weed

preemergence

.

35915‐11 California

         Chemigati

on.

Sprinkler

irrigation.

Weed

preemergence

.

19713‐273 California

   1.60072 3.20144 2 / yr NS Band

treatment

.

Band

sprayer.

Fall. 35915‐11 Arizona

         Broadcast

.

Ground. Fall. 35915‐11 Arizona

         Spot

treatment

.

Ground. Fall. 35915‐11 Arizona

         Chemigati

on.

Sprinkler

irrigation.

Fall. 19713‐273 Arizona

ORANGE 8.0036 8.0036 1 / yr NS Band

treatment

.

Band

sprayer.

Spring. 35915‐11 Florida

   4.0018 8.0036 2 / yr NS Broadcast

.

Ground. Spring. 35915‐11 Florida

         Chemigati

on.

Sprinkler

irrigation.

Spring. 19713‐273 Florida

   4.0018 NS NS Band

treatment

.

Band

sprayer.

Weed

preemergence

.

35915‐11 California,Texas

         Broadcast

.

Ground. Weed

preemergence

.

35915‐11 Texas,California
44 

         Spot

treatment

.

Ground. Weed

preemergence

.

35915‐11 California,Texas

         Chemigati

on.

Sprinkler

irrigation.

Weed

preemergence

.

19713‐273 California,Texas

   1.60072 3.20144 2 / yr NS Band

treatment

.

Band

sprayer.

Fall. 35915‐11 Arizona

         Broadcast

.

Ground. Fall. 35915‐11 Arizona

         Spot

treatment

.

Ground. Fall. 35915‐11 Arizona

         Chemigati

on.

Sprinkler

irrigation.

Fall. 19713‐273 Arizona

Orchards        

APPLE 4.0018 4.0018 1 / yr NS Band

treatment

.

Band

sprayer.

Weed

preemergence

.

35915‐11

         Broadcast

.

Ground. Weed

preemergence

.

35915‐11

         Spot

treatment

.

Ground. Weed

preemergence

.

35915‐11

   3.9995 3.9995 1 / yr NS Chemigati

on.

Sprinkler

irrigation.

Weed

preemergence

.

19713‐273

AVOCADO 4.0018 4.0018 1 / yr NS Band

treatment

.

Band

sprayer.

Weed

preemergence

.

35915‐11 Florida,California

         Broadcast

.

Ground. Weed

preemergence

.

35915‐11 Florida,California

         Spot

treatment

.

Ground. Weed

preemergence

.

35915‐11 Florida,California

         Chemigati

on.

Sprinkler

irrigation.

Weed

preemergence

.

19713‐273 California,Florida

CHERRY 4.0018 4.0018 1 / yr NS Band

treatment

.

Band

sprayer.

Weed

preemergence

.

35915‐11

         Broadcast

.

Ground. Weed

preemergence

.

35915‐11

         Spot

treatment

.

Ground. Weed

preemergence

.

35915‐11

         Chemigati

on.

Sprinkler

irrigation.

Weed

preemergence

.

19713‐273

NECTARINE 2.0009 2.0009 1 / yr NS Band

treatment

.

Band

sprayer.

Weed

preemergence

.

35915‐11 California

OLIVE 4.0018 4.0018 1 / yr NS Band

treatment

.

Band

sprayer.

Fall. 35915‐11

         Broadcast

.

Ground. Fall. 35915‐11

         Spot

treatment

.

Ground. Fall. 35915‐11
45 

         12

mon

Band

treatment

.

Band

sprayer.

Winter. 35915‐11

         Broadcast

.

Ground. Winter. 35915‐11

         Spot

treatment

.

Ground. Winter. 35915‐11

   3.9995 3.9995 1 / yr NS Band

treatment

.

Band

sprayer.

Fall. 19713‐273

         Broadcast

.

Ground. Fall. 19713‐273

         Chemigati

on.

Sprinkler

irrigation.

Fall. 19713‐273

         Spot

treatment

.

Ground. Fall. 19713‐273

PEACH 4.0018 4.0018 1 / yr NS Broadcast

.

Ground. Weed

preemergence

.

35915‐11 Oklahoma,Louisiana

,East of Miss.

River,Missouri,Texa

s,Arkansas

         Spot

treatment

.

Ground. Weed

preemergence

.

35915‐11 Oklahoma,Louisiana

,East of Miss.

River,Missouri,Texa

s,Arkansas

         Chemigati

on.

Sprinkler

irrigation.

Weed

preemergence

.

19713‐273 Arkansas,Oklahoma,

Texas,Louisiana,Mis

souri,East of Miss.

River

PEAR 4.0018 4.0018 1 / yr NS Band

treatment

.

Band

sprayer.

Weed

preemergence

.

35915‐11

         Broadcast

.

Ground. Weed

preemergence

.

35915‐11

         Spot

treatment

.

Ground. Weed

preemergence

.

35915‐11

         Chemigati

on.

Sprinkler

irrigation.

Weed

preemergence

.

19713‐273

PERSIMMON 0.9 NS NS NS Broadcast

.

Ground. Seed bed. MD980002 Maryland

PLUM 4.0018 4.0018 1 / yr NS Band

treatment

.

Band

sprayer.

Weed

preemergence

.

35915‐11 East of Miss.

River,Missouri; NOT

ALLOWED IN

TENNESSEE

         Broadcast

.

Ground. Weed

preemergence

.

35915‐11 East of Miss.

River,Missouri; NOT

ALLOWED IN

TENNESSEE

         Spot

treatment

.

Ground. Weed

preemergence

.

35915‐11 East of Miss.

River,Missouri; NOT

ALLOWED IN

TENNESSEE

         Chemigati

on.

Sprinkler

irrigation.

Weed

preemergence

.

19713‐273 East of Miss.

River,Missouri; NOT

ALLOWED IN

TENNESSEE

TURF        
46 

GOLF COURSE

TURF

2.0009 3.00135 NS NS Broadcast

.

Ground. Weed

preemergence

.

35915‐11 Specific region

(refer to the issues

report)

         Established

plantings.

35915‐11 Specific region

(refer to the issues

report)

         Chemigati

on.

Sprinkler

irrigation.

Weed

preemergence

.

19713‐273 Specific region

(refer to the issues

report)

         Established

plantings.

19713‐273 Specific region

(refer to the issues

report)

RESIDENTIAL

LAWNS

1.68750

68

NS NS 30 d Broadcast

.

Ground. Late winter. 19713‐273

         Fall. 19713‐273

         Broadcast

.

Ground. Weed

postemergenc

e.

19713‐273

ORNAMENTAL

SOD FARM

(TURF)

4.0018 6.0027 NS NS Broadcast

.

Ground. Seed bed. 35915‐11 Florida

         Established

plantings.

35915‐11 Florida

         Chemigati

on.

Sprinkler

irrigation.

Seed bed. 19713‐273 Florida

         Established

plantings.

19713‐273 Florida

ORNAMENTAL

LAWNS AND

TURF

2.0009 3.00135 NS NS Broadcast

.

Ground. Weed

preemergence

.

35915‐11 Specific region

(refer to the issues

report)

         Established

plantings.

35915‐11 Specific region

(refer to the issues

report)

         Chemigati

on.

Sprinkler

irrigation.

Weed

preemergence

.

19713‐273 Specific region

(refer to the issues

report)

         Established

plantings.

19713‐273 Specific region

(refer to the issues

report)

Tree Nuts      

ALMOND 2.0009 2.0009 1 / yr NS Band

treatment

.

Band

sprayer.

Weed

preemergence

.

35915‐11 California

BLACK

WALNUT

(FOREST)

3.96 lb /

gal

3.96 1 / yr NS Band

treatment

.

Band

sprayer.

Spring. 35915‐12

         Pretransplant. 35915‐12

         Posttransplant

.

35915‐12

         Broadcast

.

Ground. Spring. 35915‐12

   0.9 NS NS NS Broadcast

.

Ground. Seed bed. MD980002 Maryland

FILBERT

(HAZELNUT)

4.0018 4.0018 NS NS Band

treatment

.

Band

sprayer.

Fall. 35915‐11

         Broadcast

.

Ground. Fall. 35915‐11
47 

         Spot

treatment

.

Ground. Fall. 35915‐11

         Chemigati

on.

Sprinkler

irrigation.

Fall. 19713‐273

MACADAMIA

NUT

(BUSHNUT)

4.0018 4.0018 1 / yr NS Band

treatment

.

Band

sprayer.

Preharvest. 35915‐11

         Broadcast

.

Ground. Preharvest. 35915‐11

         Spot

treatment

.

Ground. Preharvest. 35915‐11

         Chemigati

on.

Sprinkler

irrigation.

Preharvest. 19713‐273

PECAN 4.0018 4.0018 1 / yr NS Band

treatment

.

Band

sprayer.

Weed

preemergence

.

35915‐11 Not allowed in:

Specific area (refer

to the issues

report),New

Mexico,California,Ar

izona

         Broadcast

.

Ground. Weed

preemergence

.

35915‐11 Not allowed in:

Specific area (refer

to the issues

report),New

Mexico,California,Ar

izona

         Spot

treatment

.

Ground. Weed

preemergence

.

35915‐11 Not allowed in:

Specific area (refer

to the issues

report),New

Mexico,California,Ar

izona

         Chemigati

on.

Sprinkler

irrigation.

Weed

preemergence

.

19713‐273 Not allowed in

Arizona,Specific

area (refer to the

issues

report),California,N

ew Mexico

WALNUT

(ENGLISH/BLA

CK)

4.0018 4.0018 1 / yr NS Band

treatment

.

Band

sprayer.

Weed

preemergence

.

35915‐11

         Broadcast

.

Ground. Weed

preemergence

.

35915‐11

         Spot

treatment

.

Ground. Weed

preemergence

.

35915‐11

         Chemigati

on.

Sprinkler

irrigation.

Weed

preemergence

.

19713‐273

Ornamentals        

NURSERY

STOCK

3.00135 3.00135 1 / yr NS Broadcast

.

Ground. Spring. 35915‐11

         Fall. 35915‐11

         Chemigati

on.

Sprinkler

irrigation.

Spring. 19713‐273

         Fall. 19713‐273

Forestry Uses        
48 

CHRISTMAS

TREE

PLANTATIONS

4.0018 4.0018 1 / yr NS Broadcast

.

Ground. Posttransplant

.

35915‐11

         Fall. 35915‐11

         Chemigati

on.

Sprinkler

irrigation.

Posttransplant

.

19713‐273

         Fall. 19713‐273

   2 4 2 / yr NS Band

treatment

.

Ground. Posttransplant

.

19713‐553 Specific region

(refer to the issues

report)

         Broadcast

.

Ground. Dormant. 19713‐553 Specific region

(refer to the issues

report)

   1.99969

4

4 2 / yr NS Band

treatment

.

Band

sprayer.

Posttransplant

.

19713‐171 Specific region

(refer to the issues

report)

         Broadcast

.

Ground. Dormant. 19713‐171 Specific region

(refer to the issues

report)

OAK

(FOREST/SHEL

TERBELT)

0.9 NS NS NS Broadcast

.

Ground. Seed bed. MD980002 Maryland

SHELTERBELT

PLANTINGS

4.0018 4.0018 1 / yr NS Broadcast

.

Ground. Posttransplant

.

35915‐11

         Fall. 35915‐11

         Chemigati

on.

Sprinkler

irrigation.

Posttransplant

.

19713‐273

         Fall. 19713‐273

   1.99863 3.99726 2 / yr NS Broadcast

.

Ground. Early spring. SD040005 South Dakota

         Dormant. SD090009 South Dakota

LOBLOLLY

PINE (FOREST)

3.96 lb /

gal

3.96 1 / yr NS Band

treatment

.

Band

sprayer.

Spring. 35915‐12 Southern States

SLASH PINE

(FOREST)

     Pretransplant. 35915‐12 Southern States

WHITE PINES

(FOREST)

     Posttransplant

.

35915‐12 Southern States

         Broadcast

.

Ground. Spring. 35915‐12 Southern States

         Pretransplant. 35915‐12 Southern States

         Posttransplant

.

35915‐12 Southern States

         Spot

treatment

.

Ground. Spring. 35915‐12 Southern States

         Pretransplant. 35915‐12 Southern States

         Posttransplant

.

35915‐12 Southern States

Ornamental

Aquaria

      

ORNAMENTAL

PONDS/AQUA

RIA

.004685

63 lb /

720 gal

NS NS 6 d Water

treatment

.

Product

container.

Initial/Subseq

uent/mainten

ance.

9712‐8