0055'
                                                                      January 1992
«y
                                     FINAL



                     DRINKING WATER C3UTERIA DOCUMENT0

                                     FOR

                                   SIMAZINE
                          Health and Ecological Criteria Division
                             Office of Science and Technology
                                   Office of Water
                           U.S. Environmental Protection Agency
                                Washington, DC 20460
   I-
    CM
                                       HEADQUARTERS LIBRARY
                                       ENVIRONMENTAL PROTECTION AGENCY
                                       WASHINGTON, D.C. 20460

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     Simazine Criteria Document
                               CONTENTS


LIST OF TABLES  	ui

LIST OF FIGURES	iii

FOREWORD 		  iv

L SUMMARY	 M

IL PHYSICAL AND CHEMICAL PROPERTIES 	H-l
   A.  GENERAL PROPERTIES	DM
   B.  MANUFACTURE AND USES 	n-1
   C.  ENVIRONMENTAL FATE	.'	H-3
   D.  SUMMARY 	n-4

m.  ToxicoioNEncs 	ni-i
   A.  ABSORPTION	EM
   B.  DISTRIBUTION 	ffl-1
   C  METABOLISM	IH-3
   D.  EXCRETION	ffl-5
   E.  BIOACCUMULATION AND RETENTION	ID-6
   F.  SUMMARY	HI-6

IV. HUMAN EXPOSURE	IV-1

V.  HEALTH EFFECTS IN ANIMALS	V-l
    A. SHORT-TERM EXPOSURE	 V-l
      1.  Lethality			V-l
      2.  Subacute Toxicity	V-3
    B. LONG-TERM EXPOSURE	V^
      1.  Subchronic  Toxicity	V-4
      2.  Chronic Toxicity		".	V-7
    C REPRODUCnVE/TERATOGENIC EFFECTS . . . .'	V-17
    D. MUTAGENICITY  ..	V-23
      1.  Gene Mutation Assays (Category 1)		V-23
      2.  Chromosome Aberration Assays  (Category 2)	V-25
      3.  Other Mutagenic Mechanisms (Category 3) I	V-25
    E. CARdNOGENICITY	V-26
      1.  Female Rats 	V-27
      2.  Male Rats	V-33
    F. SUMMARY	V-39

 VL HEALTH EFFECTS IN'HUMANS	VI-1
    A. CLINICAL CASE  STUDIES . .	. . . VI-1
    B. EPIDEMIOLOGICAL STUDIES	VI-1
    C HIGH-RISK POPULATIONS	VI-1
    D. SUMMARY  	VI-1

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Simazine Criteria Document
   C' HIGH-RISK POPULATIONS 	 VI-1
   D.  SUMMARY  	 VI-1

Vn. MECHANISMS OF TOXTCITY	  VH-l

Vm.  QUANTTHCATTON OF TOXICOLOGICAL EFFECTS	vTH-l
   A.  PROCEDURES FOR QUANTIFICATION OF TOXICOLOGICAL EFFECTS	VEI-1
      1. Noncarcinogenic Effects	•	VET-1
      2. Carcinogenic Effects  	'.	, . . . .	vm-3
   B.  QUANTIFICATION OF NONCARCINOGENIC EFFECTS FOR SIMAZINE  	VEI-5
      1. One-day Health Advisory	'	"..	 VUJ-5
      2. Ten-day Health Advisory	'	'.	VEI-5
      3. Longer-term Health Advisory	'	VHI-8
      4. Reference Dose and DrinJdng Water Equivalent Level	VHI-9
   C.  QUANTIFICATION OF CARCINOGENIC EFFECTS FOR SIMAZINE  .	VDI-12
      I. Categorization of Carcinogenic Potential  	vni-12
      2. Quantitative Carcinogenic Risk Estimates	-.	VttI-13
   D.  EXISTING GUIDELINES AND STANDARDS	VHI-15
   E.  SUMMARY ;	,	VTH-15

DC REFERENCES	K-li

APPENDIX:  HUMAN EXPOSURE
                                      u

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    Simazine Cr/.eria Document
                                        LIST OF TABLES

    Table E-l. Physical and Chemical Properties of Simazine	n-2
    Table ffl-l.  :*C Residue Levels in Tissues of Sprague-Dawley Rats 7
       Days After Receiving Single Oral Doses of '"C-Simazine	^ .  m-2
    Table V-l. Toxicological Effects of Single Doses of
       Commercial Simazine Administered to Sheep  	V-2
    Table V-2.- Orai Toxicicy of Simazine in Sheep'Following                        '       .
       Administration of Various Dosing Regimens. .	•	V-8
 .   Table V-3. Experimental Design for the Chronic/Carcinogenicity Study With Rats	V-ll
    Table \M. Schedule  for Hematology, Blood •Chemistry, and Urinalyses for the
       Chronic/Carcinogenicity Study With Rats	V-13
"£,   Table V-5. Summary of Histopathological Lesions in Male Rats Fed Diets
 *•"     Containing Simazine for 2 Years	V-28
 „  Table V-6. Summary of Histopathological Lesions in Female Rats Fed Diets
       Containing Simazine for 2 Years	•	V-29
   Table V-7. Incidence of Mammary Gland Tumors in Female Rats Fed Diets
       Containing Simazine for 2 Years*	:	V-30
   Table V-8. Incidence of Mammary Gland Tumors in Sprague-Dawley Rats Fed Simazine
       for 2 Years—Female Mammary Gland Tumor Rates and Peto Prevalence Test Results  .. .  V-31
   Table V-9.  Incidence of Pituitary Tumors in Sprague-Dawley Rats Fed Simazine                 f
       for 2 Years—Female Pituitary Gland Tumor Rate, Fatal Tumor
       Analysis, and Generalized K/W Test Results	V-34
   Table V-10.  Incidence of Kidney Tumors in Sprague-Dawley Rats Fed Simazine                      ..
       for 2 Years—Female Kidney Tubule Tumor Rate, Cochran-Armitage                              ||
      Trend Test, and Fisher's Exact Test Results  	V-35
   Table V-ll.  Incidence of Liver Tumors in Sprague-Dawley Rats Fed Simazine
      for 2 Years—Male Liver Tumor Rate, Cochran-Armitage Trend Test,
      and Fisher's Exact Test Results	  V-36
   Table V-l2.  Incidence of Thyroid Tumors in Sprague-Dawley Rats Fed Simazine
      for 2 Years—Male Thyroid C-Cell Tumor Rates and Peto Prevalence Test Results	V-37
   Table V-13,  Incidence of Kidney Tumors in Sprague-Dawley Rats Fed Simazine
      for 2 Years—Male Kidney Tubule Tumor Rates and Peto Prevalence Test Results 	V-38
   Table VTH-1,  Summary of Candidate Studies for Derivation  of the Ten-day
      Health  Advisory for Simazine  	Vm-6
   Table VIE-2.  Summary of Candidate Studies for Derivation  of the DWEL for Simazine ..  VHI-11
   Table VHI-3.  Summary of Candidate Studies Considered for Derivation of the
      Carcinogenic Risk Estimates for Simazine	Vffl-14
   Table VTJI-4.  Summary of Quantification of Toxicoiogical Effects for Simazine  	Vffl-16



                                      LIST OF FIGURES

   Figure ffi-1.  Proposed In Vivo Metabolism of Simazine in Rats	IH-4
                                              111

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Simazine Criteria Document
                                       FOREWORD
    Section 1412 (b)(3)(A) of the Safe Drinking Water Act, as amended in 1986, requires the
Administrator of the Environmental Protection Agency to publish Maximum Contaminant Level Goals
(MCLGs) and promulgate National Primary Drinking Water Regulations for each contaminant, which,
in the judgment of the Administrator, may have an adverse effect on public health and which is known
or anticipated to occur in public water systems.  The MCLG is nonenforceable and is set at a level at
which no known or anticipated adverse health effects in humans occur and which allows for an adequate
margin of safety.  Factors considered in setting the MCLG include health effects data and sources  of
exposure other than drinking water.

    This document'provides the health effects basis to be considered in establishing the MCLG.  To
achieve this objective, data on pharmacokinetics, human exposure, acute and chronic toxicity to animals
and humans, epidemiology, and mechanisms of toxicity were evaluated.  Specific emphasis is placed on
literature data providing dose-response information.  Thus, while the literature search and evaluation
performed in support of this document was comprehensive, only the reports considered most pertinent
in the derivation of the MCLG are cited in the document  The comprehensive literature data base in
support of this document includes information published up to July 1989; however, more recent data may
have been added during the review process.
                                                                                          i.
    When  adequate health effects data exist. Health Advisory values for less-than-lifetime exposures
(One-day, Ten-day, and Longer-term, approximately 10% of an individual's lifetime) are included in this
document.  These values  are  not used  in-setting the MCLG, but serve as informal guidance  to
municipalities and other organizations when emergency spills or contamination situations occur.
    James R. Elder
    Director
    Office of Ground Water and Drinking Water
Tudor T. Davies
Director
Office of Science and Technology
                                              IV

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 Simazine Criteria Document
                                         I.  SUMMARY

     Simazine (CAS No. 122-34-9) is the common name for 2-chloro-4,6-bi5(ethylamino)-l,3,5-niazine.
 It is a herbicide belonging to the triazine family of pesticides.  It is a noncorrosive, nonflammable,
 colorless, crystalline  solid with low water solubility (3.f  mg/L at 20°C).  It is formulated as a powder
 and marketed under the trade names Aquazine, Gesatop, Primatol S, or Princep.

     Simazine is produced by the reaction of cyanuric chloride with two equivalents of ethylamine in the
 presence of an acid acceptor. It is used at a rate of 0.5 to 4 kg/hectare (ha) as a selective preemergent
 herbicide for the control of annual grasses and broadleaf weeds, in deep-rooted crops, and at higher rates
 (5 to 20 kg/ha) for nonselective control of herbaceous weeds on noncropland.  Simazine is also approved
 for selective control of algae and submerged weeds in ponds and small bodies of water. Forestry uses,
 all uses on alfalfa, and uses on drainage ditch banks, forage Bermuda grass  and hay, and grass grown
 for seed in the Pacific Northwest were canceled prior to January 1989.
                                                                                               i
     Simazine is reported to have relatively low mobility in soil, mostly remaining in the upper 5 cm of
 the soil profile for several months after application.  Degradation is reported  to occur via chemical
 hydrolysis and microbial breakdown.  The half-life of simazine in soil has been estimated to be 4 to 6
 months.  The half-life  in water has been reported to be 50 to 70 days, with 99% loss in 12 months.
 Based on its physicochemical  properties, its persistence in water and soil, and the mobility of the
 pesticide and its degradates, simazine can potentially contaminate ground and surface water.  In fact, its
 presence has been detected in these waters.

     Little information on the toxicokinetics of simazine  in animals was located in the available literature.
. Data for goats, sheep, and rats suggest that about 70 to 74% of an oral dose may be absorbed. Simazine
 was metabolized by rats, rabbits, and ruminants to yield the mono- and di-N-dealkylated metabolites,
 without disruption of the triazine ring.  Limited data suggest that the principal route of excretion is the
 urine, with peak urinary levels  occurring several days  after exposure.

     The acute oral LDio estimates are 5,000 mg/kg or higher in rats, mice, rabbits, and birds, but a dose
 of 500 mg/kg  has been  reported to  be lethal  in sheep.   Pharmacotoxic signs in sheep  included
 incoordination. tremors, weakness, cyanosis,  and clonic convulsions.  A dose of 4,200 mg/kg caused
 anorexia, weight loss, and some lethality in rats.

                                               1-1

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                  Simazine Criteria Document
I*:
    In rats, short-term oral administration of 500 mg/kg/day caused death in 11 to 20 days.  A dose level
of 15 mg/kg/day was found to produce mild hepatic degeneration in 3 days, but this condition did not
progress with repeated dosing.  The validity of these data is questionable.'

    Simazine orally administered to albino  mice at dose levels ranging  from 0 to 4,500 mg/kg/day
showed no discernible adverse effects in gross pathology, food consumption, and body weight at levels
up to 450 mg/kg/day at the end of 28 days.  A NOAEL of 450 mg/kg/day has been identified from this
study.                                 .     .

    Daily oral administration of simazine at  50, 100, or 400 mg/kg/day for 31, 14, or 9 days, respect-
ively, produced death in Delaine sheep. Toxic symptoms consisted of muscular spasms, fasiculation,
stiff gait, and increased breathing.

    Simazine applied dermaily to rabbits at doses up to 1 g/kg for 21 days produced neither-systemic
toxicity, dermal irritation, nor dermal sensitization.                       .                       ,
                     0
    No treatment-related deaths were observed in rats fed simazine at dose levels up to 343 mg/kg/day
(4.000 ppm in females for 13 weeks), but decreases in body weight gain and changes in hematological
parameters were noted. Histopathology revealed dose-related increased incidences of renal calculi and
renal epithelial hyperplasia in males, which was significant at the highest dose. Based on these findings,
a NOAEL. of less than 10 mg/kg/day was identified. The same protocol was used to study the effects
of simazine  in dogs,  and a NOAEL of approximately 7 mg/kg/day  was  identified based on reduced
serum albumin and increased serum globulin, and elevated urinary ketone bodies at 64 to 65 mg/kg/day.
A 6-month study in rats and guinea pigs indicated that a dose of 20 mg/kg/day had no effect, but a dose
of 100 mg/kg/day suppressed normal weight gain and caused an increase in leukocyte count Lower
doses (1.4 to 25 mg/kg/day) have been reported to cause hypothyroidism in sheep following daily doses
for 63 to 142 days.
                     A detailed 95-week chronic feeding study in Crl:CDl(lCR)BR mice revealed a NOAEL of 6 mg/kg'
                  day and a LOAEL of 150 mg/kg/day based on decreased body weight gain. The body weight reductions
                  were significant (p <0.0l) at dose levels of 150 and 600 mg/kg/day.  Hematocrit and hemoglobin values
                  tended  to be lower in high-dose  mice than in controls.  Amyloidosis was more pronounced in all dose
                  groups  than in controls; this and other incidental effects were not considered to be compound related.
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Simazine Criteria Document
Another chronic feeding toxicity study (17 to 22 months) with Charles River CD-I mice receiving dose
levels ranging from 0 to 300 mg/kg/day was determined to be invalid.

    A recent 2-year chronic feeding study in Sprague-Dawley rats established a NOAH, of 0.52 mg/kg/
day and a LOAEL of 5.3  mg/kg/day based on decreased body weights and hematological indices (red
blood cell count, hemoglobin concentration, and hematocrit in females).  In an earlier 2-year feeding
study in rats, doses up to  100 ppm in the diet (about 5 mg/kg/day) did not produce apparent systemic
toxicity.                                                     •                  '  •
             f.
    A 1-year chronic feeding study in beagles also revealed a NOAEL of 0.72/mg/kg/day (0.76 and 0.68
mg/kg/day for females and males, respectively) and a LOAEL of 3.6 mg/kg/day based  on decreased
body weight gain, erythrocyte count, and hemoglobin concentration, and a nominal increase in platelets
in females. In an earlier 2-year feeding study in beagles, doses up to 150 ppm (about 3.5 mg/kg/day)
were without effect.  However, a dose of 1,500 ppm (about 35 mg/kg/day) resulted in  slight thyroid
hyperplasia  and  a slight increase in  serum alkaline phosphatase and  serum glutamic-oxaloacetic
transaminase activities.  However, neither chronic toxicity nor oncogenic potential could be determined
from this study.

    A two-generation reproductive toxicology study in rats fed simazine technical (96.9% pure)  in the
diet at 10, 100, and 500  ppm  levels produced no adverse health effects at 10 ppm and a transient
treatment-related reduction in weight gain at  100 ppm.  At 500 ppm, observed adverse effects included
reduced weight gain and increased mean relative testicular and ovarian weights. No effect on reproduc-
tive parameters, pup survival weights, sex  ratios, or malformation at any dose  level was produced.
Additionally, remarkable  gross  or histopathological  findings were absent in any of the examined*—*•-•
generations.  This study  suggested a reproductive NOAEL of  500 ppm  and a  parental NOAEL of-
10 ppm for simazine technical.                                                       .         -   .  '

    In a three-generation reproduction study with Charles River rats fed simazine SOW in the diet at 50
or 100 ppm, a parental toxicity  NOAEL of less than 50 ppm and a LOAEL of 50 ppm were identified
based on  reduced weight gains in males during the  premating periods.  The reproductive toxicity
NOAEL/LOAEL  could not  be  detected in this study because the apparent sterility in FH,  generation
males was not evaluated.
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Sirnazine Criteria Document


    In a teratology study with rats, simazine administered at high doses (78 and 2,500 mg/kg/day) during
gestation days 6 through 15 delayed fetal development  and was embryotoxic but not teratogenic.
Another teratology study in CrkCOBS CD SD BR rats administered simazine by gavage at doses of 30,
300, and 600 mg/kg/day  on  gestation days 6 through 15 revealed developmental and maternal toxicity
NOAELs of 30 mg/kg/day and LOAELs of 300 mg/kg/day based on skeletal variations (incomplete
ossification) in fetuses and decreased weight gain in dams.  However, the U.S. EPA has raised  some
questions and has requested additional information for this study.  Similarly,  maternal tpxicity was
observed in New Zealand rabbits given oral doses of 75 or 200 mg simazine/kg on gestation days  7-19.
The maternal toxicity NOAEL was 5 mg/kg/day based on decreased body weight gain, tremors, and
abortions at higher levels. The teratogenic NOAEL was 200 mg/kg/day, and this dose produced reduc-
tions in fetal body weight and fetal skeletal variations. The fetotoxic NOAEL was 75 mg/kg/day. Doses
of 6 'or 25 mg/kg/day administered to sheep for 142 days or 37 to 111 days, respectively, caused
decreased spermatogenesis.

                                                                       *                   *.
    Most tests of mutagenic potential for simazine have .been negative, both in  procaryotic and
                                                                                          i
eucaryotic systems.  The herbicide was  nonmutagenic in the S<2/m0ne//o/rnicrosome assay, mitotic
recombination assay in Saccharomyces, and unscheduled DNA synthesis assay in human fibroblasts.
However, it induced sex-linked recessive lethal mutations in Drosophila and sister chromatid exchanges
in human lymphocytes.
    No increase in tumor frequency and/or neoplastic lesions was observed in C57BL/6 x C3H/Anf and
C57BL/6 x AKR mice dosed with simazine at 215 mg/kg/day by stomach tube for 18 months.  A 95-
week feeding toxicity/oncogenicity study in CrhCDl  mice fed diets containing 40, 1,000, or 4,000 ppm
simazine revealed no evidence suggestive of oncogenic activity.  A chronic 2-year oncogenicity
                                                                                         i
with Sprague-Dawley rats fed simazine  at dietary  levels  of  10, 100. and  1,000 ppm revealed the
occurrence of  mammary  rumors at 100  ppm (5.3  mg/kg/day) and 1,000 ppm (63.1  mg/kg/day)  in
females; in males, simazine appeared to induce the formation of liver tumors at 1,000 ppm (45.8 mg/kg/
day).
    Almost no information is available regarding simazine toxicity in humans. One study reported acute
and subacute dermatitis in workers at plants manufacturing simazine.
                                             1-4

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Simazine Criteria Document
    The mechanism of simazine toxicity in animals is not known. Simazine has been reported to inhibit
the activity of plant, animal, and yeast alcohol dehydrogenases.  When tested with HeLa cells, simazine
had no effect on the incorporation of labeled amino acids into protein or labeled uridine into RNA.

    No suitable studies were found to permit calculation of the One-day and Ten-day Health Advisories
(HAs).  Consequently, the Longer-term HA value for a child is used as a conservative estimate of the
One-day and Ten-day HA values. The Longer-term HA value for simazine was calculated to be 70 ug/L
for a child and 300 ug/L for an adult.  However, it is advisable that the Longer-term HA value of
70 ug/L for a 10-kg child also be used as the Longer-term HA value for a 70-kg adult because the
relative  source contribution for Longer-term dietary exposure for adults could not be determined at this
time from the available data.  A 2-year chronic toxicity study in rats is used as the basis for calculation
of a Reference Dose (RfD) of 5 ug/kg/day, and for a DWEL of 180 ug/L for simazine.

    Based on available data, simazine was found to produce mammary tumors in female rats and liver
tumors in male rats. Simazine was determined to be a Category C oncogen.  The excess cancer risk has
been determined for simazine.  The Q!* was estimated to be 1.2 x 10"l (mg/kg/day)"1 in human equiva-
lents.  The oncogenic risk of exposure  to 1 ppb simazine in drinking water is 3.4 x 10"6, assuming that
a 70-kg man consumes 2 liters of water per day.
                                             1-5

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                        n. PHYSICAL AND CHEMICAL PROPERTIES

 A. GENERAL PROPERTIES

    Simazine (CAS No. 122-34-9) is the common name for the compound known alternatively as 2-
 cnloro-4,6-bis(ethylamino)-l,3,5-aiazine (International Union of Pure and Applied Chemistry) or 6-
 chloro-N,N'-diethyl-l,3,5-triazine-2,4-diamine (Chemical Abstracts). It is a herbicide belonging to the
 triazine family of pesticides. It is a noncorrosive, nonflammable, colorless, crystalline solid (Worming,
 1979; Weed Science Society of America, 1983). The physical and chemical properties of simazine are
 shown in Table n-1.

 B.  MANUFACTURE AND USES

    Simazine is produced by the reaction of cyanuric chloride and two equivalents of ethylamine in the
presence of an  acid acceptor  (Sittig,  1980).   Simazine  may  be applied preemergence, preplan!
incorporated, at planting, or postemergence. Application rates as high as 40 pounds of active ingredient
per acre have been used in noncrop sites such as rights-of-way.                  Simazine is used at
0.5 to 4 kg/hectare (ha) as  a selective preemergent herbicide to control annual grasses and broadleaf
weeds in deep-rooted crops (e.g., citrus, alfalfa, deciduous fruits,  olives, asparagus, corn, certain nuts,
grapevines, and various ornamental and tree nursery stock), and in turf grass sod production. It is used
at 5 to 20 kg/ha as a nonseiective herbicide to control herbaceous weeds in noncropiand (Meister, 1983;
Worthing, 1979). Simazine is also approved  for selective  control of algae and submerged weeds in
ponds, and is used to control algae in swimming pools, large aquaria, ornamental fish ponds, fountains,^
and recirculating water-cooling towers (Weed Science Society'of America, 1983).

   The estimated uses  for simazine are as follows:  30% on com (field); 10% on alfalfa (prior to the
voluntary cancellation by the registrant in 1987);  less than 22% on fruits and nuts; 27% on water
treatment sites; 3% on noncrop sites; 10% on tree nurseries (cancelled); and 9% on other nonagricultural
sites.                   Currently, simazine is registered for uses on terrestrial food crops, terrestrial
nonfood crops, noncrop sites, and aquatic nonfood sites. Forestry uses, all uses on alfalfa, and uses on
drainage ditch banks, forage Bermuda grass and hay, and grass grown for seed in the Pacific Northwest
were canceled prior to January 1989.
                                             H-1

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Simazine Criteria Document
                     Table n-1. Physical and Chemical Properties of Simazine
Property
Value
Reference
Chemical Abstracts
(CAS) Registry Number

Registry of Toxic
Effects of Chemical
Substances (RTECS)
Number

Simazine products
Chemical formula

Structure
122-34-9
XY5250000
Aquazine, Gesatop,
Primatol S, Princep

C,H,2C1NS
Lewis and Tatken (1980)
Lewis and Tatken (1980)
Worthing (1979)
Windholz (1983)

Weed Science Society of America
(1983)
Molecular weight

Melting point

Vapor pressure

Density

Stability in water


Solubility in water
201.7

226-227°C

6.1 x 10-' mmHg (20°C)

1.302 g/cm3

Little or no hydrolysis
in water

2.0 mg/L  at 0°C
3.5 mg/L  at 20°C
84,0 mg/L at 85eC
Windholz (1983)

Windholz (1983)

Meister (1984)

Esser et al. (1969)

Freed (1976)
 Weed Science Society of
 America (1983)
                                                H-2

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Simazine Crksna Document
C  ENVIRONMENTAL FATC

    Simazine has relatively low mobility in soil (Ghassemi et aL, 1981).  Several investigators have
reported that the greatest concentration of simazine remains in the upper 5 cm of the soil profile for
several months  after application (Marriage et aL, 1975; Hance et aL,  1976).  The depth to  which
simazine penetrates increases with the amount of water applied (Bumside et aL, 1961; Kozlowski and
Kuntz, 1962), up to a maximum of about 18 cm (Haque and Freed,  1974). Leaching and desorption of
simazine are lowest in soils high in clay or organic matter (Harris  and Warren, 1964; Helling,  1970).
Absorption of simazine onto soil colloids decreases with increasing pH and increasing temperature
(Talbert, 1963).  Simazine has little lateral movement in soil but can be washed along with soil particles
(Weed Science Society of America, 1983).

    Degradation of simazine in soil occurs via chemical hydrolysis and microbial breakdown (Ghassemi
et aL, 1981). Degradation follows first-order reaction kinetics with no lag period (Zimdahl et aL, 1970).
The half-life of simazine in soil has been estimated to be 4 to  6 months (Ghassemi et aL,  1981).  The
major soil metabolite is hydroxysimazine (2-hydroxy-4,6bis(ethylamino)-s-triazine) (Khan and Marriage,
1979).  The annual rate of degradation of hydroxysimazine is 80 to 85% compared with an annual
simazine degradation of over 95% (Khan and Marriage,  1979). Degradation of simazine from soil by
photodecomposition and/or volatilization is considered to be insignificant  (Weed  Science Society of
America, 1983).

    The half-life of simazine in water is 50 to 70 days, with 99% loss in 12 months (Ghassemi at aL,
1981).  The average  half-life of simazine in pond water was  reported to be 30 days (Weed Science
Society of America, 1983). According to the manufacturer, water from treated ponds may not be used
for irrigation, for watering animals, or for human consumption until  12 months following treatment
(Ciba-Geigy Corporation, 1976).

   Based on simazine's physiochemical properties, its persistence in water and soil, and the mobility of
simazine and its degradates, there is potential for contamination of ground and surface water with the
herbicide and its degradates.  In fact, detection of simazine has been reported in ground and surface
water.
                                            H-3

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 Simazine Criteria Dce-mer.t
 D.  SUMMARY

     Simazine (2-cMoro-4,6-bis(ethylamino)-i,3,5-triazine; CAS No. 122-34-9) is a herbicide belonging
 to the triazine family of pesticides.  It is a noncorrosive, nonflammable, colorless, crystalline solid with
 low water solubility (3.5 mg/L at 20°C).  Simazine is formulated as a powder and is marketed under the
 trade names of Aquazine, Gesatop, Primatol S,  and Princep.  It is currently registered for uses on
 terrestrial food crops,, and nonfood crops, noncrop sites,  and aquatic nonfood sites. Forestry  uses, all
 uses on alfalfa, and uses on drainage ditch banks, forage Bermuda grass and hay, and grass grown for
 seed in the  Pacific Northwest were canceled prior to January 1989.

     Simazine is produced by the reaction of cyanuric chloride with two equivalents of ethylamine in the
                         »
 presence of an acid acceptor.  It is used at a rate of 0.5 to 4 kg/ha as a selective preemergent herbicide
 for the control of annual grasses and broadleaf weeds in deep-rooted crops, and at higher rates (5 to 20
 kg/ha) for nonselective control of herbaceous weeds on  noncropland.  Simazine  is also approved for
 selective control of algae and submerged weeds in  ponds and small bodies  of water.                ^
                                                                                               (
    "Simazine is reported to have relatively low mobility in soil, with most remaining in the upper 5 cm
"•-''',-'.    .-*-      .-„...            fe
 of the soil profile for several  months after application.  Degradation is reported to occur via chemical
.hydrolysis and microbialbreakdown. The half-life in soil has been estimated to be 4 to 6 months.  The
 half-life of simazine in water has been reported to be 50 to 70 days, with 99% loss in 12 months.  Based
                              *
 on its physicochemical properties, its persistence in both water and soil, and the mobility of the herbicide
 and its degradates, there is potential for contamination of ground and surface water.  Detection of
 simazine  in ground and surface has been reported.
                                               E-4

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 Simazine Criteria Document
                                   HI. TOXICOKINEnCS

 A. ABSORPTION

    Orr and Simoneaux (1986) studied the metabolism of uC-simazine (uniformly labeled in the niazine
 ring), in groups of five male and five female. SpragueDawley rats following oral administration in single
•doses at 0.5 or 200 mg/kg. At the low dose, 51 to 62% of the dose was eliminated in the urine and about
 -12% was found in the tissues, suggesting that about 63 to 74% (Le., 0.315 to 0.37 mg/kg) of the dose
 was absorbed. At the high dose, only about 22% (i.e., 44 mg/kg) of the dose was found in urine and
 2% (4 mg/kg) in the tissues of males or females.  A third group of animals  received daily single oral
 doses of unlabeled simazine at 0.5 mg/kg/day for 14 days followed .by a single  14C dose.  Elimination
 of 14C in urine ranged from 59 to 66% of the dose,  and 8% was found in the  tissues.  Bakke and
 Robbins (1968) reported that in goats and sheep, from 67  to 77% of a dose (the dose was not reported
 in this abstract) of 14C-simazine (given orally in gelatin capsules) was excreted in urine.  This suggests
 absorption  was around 70%.     '                                                            (

 B.  DISTRIBUTION
    Orr and Simoneaux (1986) reported that 7 days following oral administration of l*C-simazine to male
and female Sprague-Dawley rats at 0.5 or 200 ug/kg, the highest 14C residue levels were found in the
red blood cells, accounting for 16.3 to 19.9 ppm at the high dose and 0.18 to 0.23 ppm at the low dose.
Residue levels in red blood cells were slightly higher in males  than  in females.  The data  are
summarized in Table DI-1  and expressed as percent  of dose found in individual tissues.  Lower
concentrations were found in the other tissues, ranging from 0.0 to 0.16 ppm at the low dose and from
0.78 to 5.2 ppm at the high dose. Relatively higher residues were found in the liver and kidney of rats
receiving the low dose (0.1  to 0.16 ppm), with lower levels found in fat, plasma,  and bone (0.0 to 0.03
ppm). A similar pattern was observed in rats receiving  the high dose, except that the spleen contained
higher MC residues (4.1 to 5.2 ppm) than the liver and kidney (2.9 to 4.0  ppm).

    Residue levels in tissues of animals receiving the low 14C dose following 14 days of repeated dosing
were generally lower than those observed in rats receiving a single low dose, except in red blood cells
(see Table ffi-1).  The authors suggested that repeated dosing with unlabeled simazine  significantly
reduced the number of available binding sites in all tissues, except the red blood cells.
                                             m-i

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Sraazine Chreria Document
              Table ffl-1.  14C Residue Levels in Tissues of Sprague-Dawley Rats 7
                  . Days After Receiving Single Oral Doses of t4C-Simazine
                                       14C Residues expressed as % of dose
Tissue
Heart
Lung
Spleen
Kidney
Liver
Fat
Testes/Uteius
Muscle
Brain
Carcass
Plasma
RBC
Bone
Total
0.5 me/kg Csinele')
Males Females
0.04 '
0.06
0.02
0.23
1.08
0.19
0.11
2.76 .
0.09
5.40
0.16
1.13
0.01
11.79
0.04
0.05
0.03
0.15
1.26
0.09
0.01
3.28
0.10
6.34
0.07
0.83
0.01
12.26
0,5 mg/kg
Males
0.08
0:03
0.02
0.10
0.88 •
0.29
0.05
1.61
0.04
3.99
0.04
1.13
0.01
8.21
(repeated*)*
Females • •
0.03
• 0.04
0.02
0.10
0.90
-0.26
0.01
1.54
0.05
3.63
0.03
1.10
0.01
7.73 •
200 mg/kg Csingle)
Males Females
0.01
0.01 '
o.or '
0.01
0.09
0.05
0.01
0.44
0.01
1.13
0.03
0.27
0.00
2.05
0.01
0.01
0.01
0.02
0.08
0.05
0.00
0.45
0.01
1.00
0.03 1
0.23
0.00 '
1.89
•Animals received daily single oral doses of unlabeled simazine followed by a single 14C dose.

SOURCE: Adapted from Orr and Simoneaux (1986).
                                           m-2

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 Simazine Criteria Document                     "      -           .


    In rats receivi g the high dose, UC residue levels, expressed as ppm, were 29-fold (kidney) to 516-
 fold (spleen) higher than those in animals receiving the low dose (Orr and Sirnoneaux, 1976).

 C. METABOLISM

    Simoneaux and Sy  (1971) conducted a preliminary investigation on  the metabolites of UC ring-
Jabeled simazine found in the urine of female white rats. The rats were orally dosed once at 1.5 mg/kg,
 and the urine eliminated within 24 hours was collected  and analyzed by thin-layer chromatography and
 thin-layer elecuophoresis.  The  metabolites identified by. comparison  to authentic  compounds were
 hydroxysimazine,  2-hydroxy4-amind-6-ethylamino-s-triazine,  and  2-hydroxy-4,6-diamino-s-oriazine.
 These metabolites accounted for 6:8, 6.1, and 14.0%  of  the administered radioactivity, respectively.
                i                                       '  •                 •       -'
 When the urine was hydrolyzed  with performic acid to cleave sulfur-carbon bonds prior to thin-layer
. chrorrtatography,  about 8.1, 7.7, and 31.3% of the radiolabel were detected  as  the. three identified
 metabolites, respectively.  Approximately half of the radioactivity in the urine  was not identified.    J
                                                                                             i
    Based on these findings, Orr  (1985) proposed the metabolic pathway for simazine  depicted in Figure
 m-L
     Bradway and Moseman (1982) investigated the metabolism of rimazine in rats. Male Charles River
 rats averaging 300 g were given simazine (suspended in peanut oil) by gavage.  Two doses of 1 mL,
 containing 0, 0.005, 0.5, 5, or 50 mg/mL, were given 24 hours apart. This corresponds to doses of 0,
 0.017, 1.7,  17, or 167 mg/kg/day, respectively.  Urine samples (24-hour intervals) were extracted and
 analyzed by gas cinematography for the presence of the mono- and di-N-dealkylated metabolites.  The
 percent of the dose excreted as these metabolites depended somewhat on the dose level, with higher
 doses yielding higher percent excretion of the metabolites. The di-N-deaikylated metabolite (2-chloro-
 4,6-diamino-s-triazine) appeared to  be the major product, ranging from 1.6% at the 0.5-mg dose to
 18.2% at the 50-mg dose, while the mono-N-dealkylated metabolite ranged from 0.35% at the 0.5-mg
 dose to 2.8% at the 50-mg dose.

     Similar results were obtained by Bohme and Bar (1967).  Albino rats (200 to 300 g) or rabbits (2
 to 3 kg) were fed simazine at levels of 50 to 200 mg/rat (200 to 800 mg/kg) or 600 to 1,000 mg/rabbit
 (240 to 400 mg/kg). Several metabolites wen: isolated and identified, all of which retained the triazine
 ring intact.  The principal metabolites were the mono- and di-N-dealkylated metabolites.
                                              m-3

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Simazine Criteria Document
     SlMAZlHf
               A.
                                    "^
                                      M
                                      1*
                                                          OM
        A,
                                                           an
                                                        A *l
                                                        'r^'-^»
                                           a
                                           i
!
                Figiue ffl-1.  Proposed /n Wvo Metabolism of Simazine in Rats
SOURCE: Adapted from Orr (1985).
                                        ffl-4

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 Simazine Criteria  Document
     Bohme and Bar (1967) and Larsen and Bakke (1975) observed that rat and rabbit urinary metabolites
 from the 2-chloro-s-triazines were all 2-chloro analogs of their respective parent molecules, and none
 of the metabolites contained the 2-hydroxy moiety. Total N-dealkylation, partial N-dealkylarion, and
 N-dealkylation with N-alkyl oxidation were suggested as the major routes of the metabolism of 2 chloro-
 s-triazines in rats and rabbits.                                                          a

     Guddewar and Dauterman (1979) purified glutathione-s-transferase 61-fold from mouse liver. This
 enzyme conjugates chloro-s-triazine herbicides.  A chloro group at the C2-position was found to be
-itf- *
 necessary for conjugation to occur.  When this 2-chloro was replaced by a methylmercapto group, no
 conjugation occurred.  The reaction rate decreased with triazine analogs lacking the alkyl side-chains.
 Atrazine was  conjugated faster than  either simazine or propazine.

     Bakke and Robbins (1968) investigated the metabolism of simazine in goats and sheep.  Animals
 were orally dosed (the dose was not reported in  this abstract) using gelatin capsules.  The sheep were
 given l4C-simazine labeled on the triazine ring or on the ethylamino side-chain, while goats were given
                                - 0
 the ring-labeled compound only. ,No 14C02 was detected from animals receiving ring-labeled herbicides,
               ~i.-~ "••••••'"«.
 which suggested that  the triazine 'ting was  not metabolized. • In sheep that received chain-labeled
 triazines,  at  least  40%  of the  ethylamino  side-chains  were  removed.   Using ion-exchange
 chromatography, 18 labeled metabolites were found in urine.

 D.  EXCRETION
     Orr and Simoneaux (1986) studied the metabolism of 14C-simazine in Sprague-Dawley rats following
 oral administration in single doses. Male and females receiving 0.5 mg/kg eliminated 50.5 and 62.1%
 of the dose, respectively, in the urine, and 19.1 and 13.3% of the dose in the feces, 7 days after dosing.
 In animals receiving a single dose of 14C-simazine following repeated dosing at 0.5 mg/kg/day for 14
 days with unlabeled simazine, males eliminated 58.5 and 24.5% of the dose  in  urine and  feces,
 respectively, whereas  females eliminated 66.0 and  17.8% of the dose.  A third  group of males and
 females receiving a single dose of 200 mg/kg eliminated about 21% of the dose in the urine and about
 2.0% in the feces.

     The elimination pattern with time after dosing was biphasic with rates being faster in females than
 males.  Most of the radioactivity  was  eliminated in 72  hours  with a half-life of 9 to  15  hours.
                                               DI-5

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 Simazir.e Criteria Document
 Elimination of the remaining radioactivity followed slower kinetics with half-life values ranging from
 21 to 32 hours. In a preliminary study with two female white rats dosed orally at 1.5 mg/kg, Simoneaux
 and Sy (1971) found less than 0.05% of the dose being eliminated as uC-carbon dioxide 96 hours after
 dosing.  Approximately 49.3% of the dose was eliminated in  the urine and 40.8% in the feces.

             »
     Bakke and Robbins (1968) studied the  excretion of simazine in lactating goats and sheep using
 triazines labeled with !*C  on the ring or on  the ethylamino side-chains. No '*C02 was detected from
 animals that  received the ring-labeled compounds, which suggested thai the triazine ring was not
   V                                 '       '
 metabolized.  Approximately 67 to 77% of the administered ring-labeled activity was found in the urine,
 and }3 to-25% was found in the feces.  About 0.1-6 ppm of 14C  residues were present in the milk
 immediately after dosing,  but the level decreased to 0.04 ppm within 48 hours.

     St. John et al. (1965) fed unlabeled simazine (5 ppm) to a lactating cow.for 3 days.  Urine and milk
• were collected and analyzed during  the feeding  period and'for 3-days .thereafter. 'No simazine was;
 detected .in the milk  (sensitivity of method approximately  0.1 ppm), and.only'about,1% of the
 administered  simazine was  excreted in the  urine as the. parent -compound. Milk, excreta, and body
                   *           '                       •'  .                 •-.-•*
. tissues were not analyzed for simazine metabolites.                         •
     *      .   *                                      "                                     .

     Hapke (1968) reported that simazine residues were present in the urine of sheep for up to" 12 days
 after administration of single oral doses of 250, 500, 630, 700,  and l-.OOO mg simazine (50% active
 ingredient)/kg. The maximum concentrations (from 6 ppm in  the low dose to 70 ppm in the high dose)
 in the urine occurred from 2 to 10 days after administration.
                                                                                            >.
 E.  BIOACCUMULATION AND RETENTION                                              '

     No studies providing quantitative information on simazine bioaccumulation or retention in mammals
 were located.

 F.  SUMMARY

     Little information is available on the toxicokinetics of simazine in animals.  Up to 74% of an oral
 dose was absorbed in Sprague-Dawley rats following a single administration of 0.5 mg "C-simazine./kg.
 The highest !4C residue levels were found in the  red blood cells 7 days following administration.  Data
                                             m-6

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 Simazine Criteria Document


 on goats and sheep  suggest that about  70% of an  oral dose  may  be absorbed.   Simazine was
 metabohzed, without hydrolysis of the triazine ring, by rats and rabbits to yield the mono- and di-N-'
 dealkylated metabolites and the corresponding 2-hydroxy derivatives resulting from dechlohnation of
 S1mazine. Similar results have been reported in ruminants. Limited data suggest that the principal route
ol excretion is the urine, with r*ak urinary levels occurring several days after exposure.  No data are
available on tissue distribution,  bioaccumulation, and retention of simazine.
                                           ra-7

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Slimline Criteria Document
                              IV.  HUMAN EXPOSURE
   Information on human exposure is presented in the appendix portion of this document.
                                        IV-1

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 Simazine Catena Document


                            V.  HEALTH EFFECTS IN .ANIMALS

 A. SHORT-TERM EXPOSURE

 1.  Lethality                      .                                             •      ,
                                                                                         . a
    The  acute oral LDJO of simazine in rats, mice, rabbits, chickens, and pigeons has been reported to
'be greater than 5,000 mg/kg (Dalgaard-Mikkelsen and Poulsen, 1962; Martin and Worthington,  1977;
 .USDA, 1984; Cosmopolitan Safety Evaluation, 1985). The acute dermal'LD50 in rabbits is more than
10,200 mg/kg (We.ed Science Society of America, 1983).
    Cosmopolitan Safety -Evaluation (1985) conducted an acute oraUoxicity study with five female and
 five male Sprague-Dawley albino rats given ,a Single oral dose of simazine in com oil at 5,000 mg/kg
 body weight (bw).  .One male and two females';died  qri day '6 or 7'following administration of
 herbicide:- No additional deaths occurred during the 2-week observation period.'
    The animals lost a significant amount of weight during the first week after dosing.  OfTdays 3
 through  10 or  11,  several  signs  of  poisoning were  observed, including chromorhinorrhea,
                                  •                 •          *
 chromodacryorrhea, perinea! and/or abdominal staining, reduced activity, emaciation, and ataxia before
 death.  Necropsy of the three rats that died during the study showed  congestion of the gastrointestinal
 tract, which contained a reddish-brown fluid.  Survivors had no pathognomonic signs at necropsy.

    Mazaev (1965) studied the effect  of a single oral dose of simazine administered to rats at 4,200
 mg/kg.  Anorexia and a loss of weight were observed, with some of the animals dying in 4 to 10 days.
 When Mazaev (1965) administered 500 mg/kg daily, all of the animals died in the period between days
 11 and 20.  The time of death was correlated with loss of weight.  No other data on acute toxicity were
 reported in this abstract.

    Hapke  (1968) administered,  by  oral intubation, single doses of commercial simazine (50% active
 ingredient) to sheep (merino meat sheep, blackheaded sheep, or milk sheep) at dose levels of 200, 250,
 500, 600, 630, 790, and 6,000 mg/kg. The numbers of deaths and  effects at  various  dose levels  are
 shown in Table V-l. No discernible  effects were noted at the 200-mg/kg dose level,  although minor
 toxicity was observed at 250 mg/kg. The lowest dose at which deaths were observed was 500 mg/kg.
                                             V-l

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Simazine Criteria Document
                      Table V-l.  Toxicological Effects of Single Doses of
                         Commercial Simazine Administered to Sheep
Dose
mg/kg
(50% a.i.)'
200
" 250 ' .
No. of
animals
5
2
No. of deaths
0"
0
Effects
No discernible effects.
Slight reduction in feed uptake,
   500
   600
   630*  *'   "
   790
6,000
6  .
Four on days
6, 7, 8, and
25

One on day 6


    0
            Three on days
            10, 12, and 16
            One on day 4
'polydipsia, apathy for 3 to 8
 days.

 Slight reduction in feed uptake,
 polydipsia, ataxia, trembling,
 salivation.

 Same as above plus slight       .       «;_
 paralysis  of the hind-legs.   :   •          *
                                        i
 Reduction in feed uptake, difficulty
 in standing, ataxia, motor inactivity.

 Difficulty in moving, paralysis of
 hindquarters,  pale   mucous   membranes,
 urination and defecation impeded.

 Trembling muscles, ataxia, clonic cramps,
 paralysis  of rear extremities,  bleeding in
 stomach mucous membrane.
"a.i. - Active ingredient.
The animals were under observation for at least 4 weeks.

SOURCE:  Adapted from Hapke (1968).
                                             V-2

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 Simazine Criteria Document
 The toxic signs in affected animals included reduction in feed uptake, pblydipsia, ataxia, paralysis .of
 extremities, and finally death.  Although the types of sheep used foE each dose were not identified, the
 authors indicated that the milk sheep, and  merino sheep were more susceptible to simazine than the
 blackheaded sheep.  A  N'OAEL of 200 mg simazine (50<&)/kg and  a LOAEt of 250 mg simazine
 (50%)/kg have been identified from this study. •
                                                •»

   • In primary irritation studies in rabbits (USDA, 1984), simazine caused transient Inflammation of the
 conjunctiva.                              •          .                      '    ft

                           "                                       *
*2.  Subacute Toxicitv    ..                           .    •
                                                                   v                   •       .
  •                                                                  *      1
   ' No lethality was.observed in rats fed 1,250 or 2,500 mg simazine/kg six times/week for 4 weeks
 (Gysin and Knusli, 1960).  Oledza-Slotwinska (1974) gave simazine via stomach tube to male albino
 rats at a dose of 15 mg/kg/day for 3 or 28 days. Histologic examination of the livef showed a few focai
 lesions in hepatic parenchyma after the first 3 days.'but the condition.did not progress.  The hepatocyies
                     
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Simazine Criteria Document
    Palmer and Radeieff (1964) found that repeated oral administration of simazine, at daily doses of
50 mg/kg for 31 days,  100 mg/kg for 14 days, or 400 mg/kg for 9 days,'was fatal to Delaine sheep.
One sheep and one dairy cow receiving daily oral doses of 250 mg/kg for 3 days survived but showed
toxic effects after one dose. Muscular spasms and fasciculation. stiff gait, and increased respiratory rates
were observed. Simazine was also  lethal  when administered  at 100 mg/day for  14 days by drench
(Palmer and Radeieff, 1969).               .  .           •          •    '            •   •
                                                                          •  °   »
    In a 21-day subacute dermal toxicity. study  in rabbits, Ciba-Geigy <198jOa) reported, that dermal
                                                                            .  o
applications of technical simazine at doses up to 1  g/kg produced no  systemic toxicity and no dose-
related alterations of the sldrh                  '.  •

B.  LONG-TERM EXPOSURE
                      •                                   ,
                         P                       a
                                                                •
1. Subchrontc Toxicitv                                                                      i
           *                 •  •                                            .                  *
                 0
    A subchronic toxicity study was carried out in 10-week-old Sprague-Dawley Cri:COB CD (SD) BR
rats (Tai et aL. 1985a). This study was reviewed by'the O.S: EPA (Robinson et aL,  1985).  Animals
were randomly assigned to one of four groups, each consisting of 10 rats/sex, and were fed technical
simazine (97.5% pure)  in a powdered feed ad libitum for  13 consecutive weeks (7 days/week).  The .
concentrations of  simazine were  0 (control), 200, 2,000, and 4,000 ppm. Hematological and clinical '
chemistry studies and urinalyses were performed on blood and urine samples collected from the animals
prior to study termination.  All surviving  animals at the  end of the  dosing period (91 days) were
necropsied, and tissues were examined histopathologically.
                                                                               r
    Significant dose-related reductions in mean body weights and mean body weight gains occurred in-
both sexes in all  treated groups.  This paralleled dose-related reductions in mean feed intake.  The
average feed intake was reduced by 52.5 and 46.4% in males  and females  receiving 4,000 ppm, by 37.2
and 32.1% in males and females receiving 2,000  ppm, and by 6.5 and 7.9% in males  and females
receiving 200 ppm, respectively.  Based on actual feed consumption, the average doses of simazine for
the 200-, 2,000-, and 4,000-ppm diets in males ranged from 9.6 to 17.4, 104.6 to  151.8, and 199.3 to
289.7 mg/kg/day, and  in females from 13.8 to 18.8, 143.3 to 186.4, and 239.2 to  343 mg/kg/day,
respectively.  Dose-related reductions were detected in  mean  erythrocyte counts in  both sexes in all
treated groups. Decreased hematocrit was detected in females dosed at 2,000 and 4,000 ppm and in

                                             V-4

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 Simazine Criteria Document
 males receiving 4,000 ppm.  Mean leukocyte counts  were significantly lower in males at ail doses.
 Neutrophil and platelet counts were significantly higher in females at the 2,000-  and 4,000-ppm dose
 levels.  Several differences in clinical chemistry and urinalysis indices occurred in treated rats compared
 with controls, including lowered blood glucose, sodium, and calcium in males; increased cholesterol and
 inorgan:c phosphorus levels in both sexes; and  decreased  levels of blood urea  nitrogen, lactic acid
 dehydrogenase, serum glutamic-oxaloacetic acid transaminase (SCOT), and  creatinine in  females.
 Elevated urinary ketone levels were seen in males, and decreased urinary protein was seen in females
 «SSt
 when compared with controls.
    Reduced absolute organ weights and increased relative organ weights were observed for the brain,
 heart, kidney, liver, and lestes in males, and for the brain and spleen in females. Other effects consisted
 of increased relative adrenal weights for both sexes, reduced absolute weight for trie spleen in males,
 and reduced absolute weights of the ovary and heart in females receiving 2,000 and 4.000 ppm. Relative
 ovarian weight was also reduced in females  receiving 4,000 ppm.  Histological examination revealed
 .a flose-related increase, in the incidences of renal calculi but no gross lesions.  The incidence of calculi,
•  ^                                   '"                   '                                     '
 renal epithelial hyperplasia, and tissue reaction to calculi were significant in males receiving 4,000 ppm.
          *  >
 The effects were most pronounced in the high-dose groups. Most  of these effects were considered to
 represent secondary changes that occurred as  a result of reduced dietary intake and reduced growth rate.
 This study suggested a NOAEL  of less than 200 ppm  (10 mg simazine/kg/day) based on adverse
 hematological and clinical chemistry indices  and dose-related incidence of renal calculi The results of
 this study were, however, considered to  be of limited  value because the reduction in food intake
 associated with the addition of simazine to the diet seriously affected the nutritional status of treated rats.

    A subchronic toxicity study for simazine  was carried out in dogs (Tai et aL, 1985b) using a protocol
 similar to that described  above and was also reviewed by the U.S. EPA (Robinson et aL, 1985)^
 Purebred 7- to 8-month-old beagle dogs (body weight ranging from 8.0 to 10.0 kg for males and 7.0 to,:
 8.6 kg for females) were assigned to one of four groups, each consisting of four/sex, and were fed diets
 containing technical grade simazine (97.5% pure) at concentrations  of 0, 200,2,000, and 4,000 ppm for
 at least 91 consecutive days.  All dogs were observed daily for mortality and signs of toxiciry. Blood
 and urine were collected from all dogs at predose and at study days 44 and 92 for hematologicai, clinical
 chemistry, and urinalysis determinations.  All dogs were sacrificed and necropsied between 93 and 98
 days of study for gross and histopathological investigation.
                                               V-5

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Simazine Catena Document
    Treaimem-related clinical signs observed in dogs receiving 4,000 ppm included alopecia, tremors,
dermatitis (males), and emesis (females). Mean daily feed consumption was significantly reduced in the
2,000- and 4,000-ppm dose groups compared with controls in both sexes throughout the 13-week feeding
period.  Males in the 4,000-ppm dose group and females in the 2,000- and 4,000-ppm dose groups lost
weight during the 13-week feeding.  Based on actual feed consumption, the average dose of simazine
for the 200-, 2,000-, and 4,000-ppm groups was 6.9, 65.2, and 133.6 mg/kg/day for males and 8.2, 64.3,
and 136.7 mg/kg/day for females, respectively.  Erythrocyte counts, hemoglobin, and hematocrit were
reduced in. both sexes dosed, at 4,000 ppm during weeks  7 and  13;  lieutrophils  were higher and
lymphocytes were lower compared with controls in males dosed at 4,000 ppm at week 13; platelet count
was increased in males receiving 400 ppm  during weeks 7 and 13; eosinophils were reduced in males
at all doses at'week 7 and  in males  receiving 4,000  ppm  at week  13;  and  prothrombin time was
significantly less in females at all doses at week 13,when compared with controls. Significantly lowered
serum albumin/increased serum globulin, and decreased albumin/globulin ratio were observed in males
receiving  2,000 and 4;000 ppm at week 13.  Serum SCOT and creatinine levels were high in males
receiving 4,000 ppm at week. 13, and calcium ions (divalent) were increased in males receiving 2,000
and 4,000 ppm at week 13 when compared with controls. Urinary ketone levels were increased in males
and females in the mid- and high-dose  groups at week 7, and in males receiving the high dose at week
                                  *        i                       *
13 when compared with controls. Although differences were found in the organ weights (especially the
                                                                                     &
heart, brain, and liver compared with controls), no gross or microscopic lesions attributable to simazine
were revealed.                     «

    This study suggested a NOAEL of  200 ppm (7 mg/kg/day) based on reduced serum albumin levels,
increased  serum globulin, and elevated urinary ketone at 2,000 ppm (maximum  tolerated dose  of
simazine). The study  authors commented that 200 ppm simazine in the diet for 1 year might result in
a decreased weight gain.  However, as with the previous study in rats, the results of this study are of
limited  value because  the reduced feed consumption seriously affected the nutritional status of test
animals.

    Mazaev (1965) administered daily oral doses of 20  or 100 mg  simazine/kg in a starch solution to
rats and guinea pigs for 6 months.  The higher level suppressed the weight gain of the animals  and
caused an increase in the number of leukocytes and a decrease in cholinesterase activity in blood during
the first 2 months of the study. No changes in the blood protein fractions,  hemoglobin  content, number
of erythrocytes, or liver carbohydrate metabolism were  evident.  However, some dystrophic changes of
                                             V-6

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Simazine Criteria Document

              »
the kidneys and atrophic gastritis were found.  This study is of minimal value because the details of
experimental design (including number of animals) were not reported in this abstract.

    Dshurov (1979) studied histological changes in the organs  of 21 sheep (29 to 48 kg, 1.5 to 6 years
old) following oral administration of various dosing regimens of sinuzine (50% active ingredient) (Table
V-2).  Fatty and granular liver degeneration, diffuse granular kidney degeneration, neuronophagia, diffuse
glial proliferation, and degeneration of ganglion cells 'in the cerebrum and medulla, were found.  Sheep
that died showed spongy degeneration, hyperemia, and edema in the cerebrum; the de"gree of change
varied with the dose of simazine and the period  of dosing.  The thyroid showed  hypofunction after
repeated daily doses of 1.4 to 6.0 mg/kg administered for periods  varying ffom 63 to 142 days. The
                       •                     '       '                                       :>
greatest antithyroid effect followed one or two doses at 250 mg/kg, which produced parenchymatous
goiter and a papillary adenoma in one of the three dosed sheep. This type of goiter was  also seen in
Sheep administered 50 or 100 mg simazine/kg once each week  for approximately 22 weeks. The report
does not provide sufficient details on dose/duration effects on which  to  base  determination  of the
NOAEL or LOAEL.                                                                 '   -f    :
                                                                                            t
                                                             «
2. • Chronic Toxicitv                       .           •      -,,<--.
    A chronic toxicity study with Swiss white, Charles River CD-I mice fed diets containing simazine
herbicide for 17 to 22 months was reported by-Ciba-Geigy (1980a).  The study was conducted by
Industrial  Bio-Test  Laboratories/Inc.  (JBT).-..The EPA has declared  this study invalid owing to
                                          
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Simazine Criteria Document
                  Table V-2.  Oral Toxicity of Simazine in Sheep Following
                         Administration of Various Dosing Regimens
No. of sheep
2

2
2
2
8
2
- .•'-* .'"" i •
.2-


. -3-- ,- .

Dose (mg/kg)
(50% a.i.)'
0

1.4
3.0
6.0 '
25
50

100
•
. -*•- — *_y ?. * '. ' ,i
250
•
Exposure duration
— b
9 '
90 and 129 days
63 and 65 -days
;-.'. "141 and- 142, days
37, 49, 63. 69, 90, and 111 days
,% . Every. 7'days for 133 days. . . '•
* -. ' • -"
Every 7 days for -15 3 days '' '"
4
i^.- 	 "— " *
One or two doses with a 20- to • :
30-day interval between doses
*a.L = Active ingredient.
bNot reported.

SOURCE: Adapted from Dshurov (1979).
                                           V-8

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 Simaz-re Criteria Document
 higher incidence of enlarged seminal vesicles in males fed the 3,000-ppm diet and a greater number of
 enlarged spleens in females fed the 15- or 1,000-ppm diets when compared with all other groups of the
 same sex.  Antemortem observations such as skin irritation, hair loss, and skin lesions reportedly were
 not compound related. No histopathological lesions were found in any of the animals.  However, this
 study is inadequate for evaluating the chronic toxicity  of simazine owing to the questionable laboratory
 practices adopted by IBT.     .                                                ,             •

    A 95-week chronic feeding toxicity/oncogenicity study ire Crl:CDl(ICR)BR mice was .recently
 reported by Hazelette and Green  (1988 for Ciba-Geigy). Simazjne of undefined purity (the same batch
 of simazine was reported to be 97.5% pure in a subchronic oral study with rats) was mixed in the diet
 at concentrations of 0,40,1,000,  or 4,000 ppm and fed to.5-week-old mice (males weighing 19.1 to 32.1
 g and females weighing 14.4 to 26.3 g). These dietary levels correspond to simazine doses of 0, 6,150,
'and 600 mg/kg/day.. However, based on actual food intake, the mean compound intake for the  entire
 study was 0,5.3,131.5, and 542 mg/kg/day for males and 0, 6.2,160, and 652.1 mg/kg/day for females.
 Body weights and food consumption were determined weekly up to week 13 and monthly thereafter.
 Water "consumption was measure
-------
 Simazine Criteria Document
 groups, the' feed consumption also correlated with body weight gains. Water consumption tended to be
 decreased in males and females receiving 1,000 and 4,000'ppm.

    Hematocrit (HCT) and hemoglobin (HGB) values in high-dose mice tended to be lower than those
 of controls.  He wever, HCT was statistically significant (p <0.05) only in males at day 184, and HGB
 was significant in females at day 365. The changes in erythroid indices, mean corpuscular volume, and
 me^n corpuscular HGB concentration did not correlate with changes in red blood cells. HCT, and HGB.
                            C                            tt                *
 Slight alterations in other  hematologic indices  were considered to be of no biologic" significance.
 Urinary  indices were normal in dosed ^groups.  No significant changes were noted'in absolute and
                                               £                    *
•relative .organ weights and  organ-to-brain weight ratios in males after  26  weeks,  52 weeks,  or at the   .
    . «
 terminal sacrifice.  There were several significant (p = 0.05 or 0.01) increases in organ-to-body weight
 ratios in females receiving 1,000 and 4,000 ppm simazine. However, these changes generally correlated
 with  reductions of body weights and were not accompanied by increases in absolute organ weights or
 organ-to-brain weight ratios. -There were no dose-related incidences  of gross pathology. Histologicallv,
 amyloidosis  was significantly increased in dosed groups compared with controls.  The incidence was
 fairly high as early as'the 52-week sacrifice (62% of males and 20% of females in all groups combined)/ „'
 When "the numbers of mice from each group with amyloidosis at any site were compared, no increase
 was related to  dosing. Amyloidosis was not considered to be related to dosing with simazine.  This
 study suggested a LOAEL of 1,000 ppm (150 mg simazine/kg/day) based on decreased weight gain and
 a NOAEL of 40 ppm (6  mg simazine/kg/day).

    The  U.S. EPA (loannou and Copley, 1988) has reviewed and evaluated  an  oral 2-year chronic
 toxicity/oncogenicity study (McCormick et al., 1988, for Ciba-Geigy) in 6-week-old Sprague-Dawley
 albino rats (males weighing 126 to 189  g, females weighing 101 to 167 g). Groups of randoml^***"
 assigned animals (40 rats/sex in the control and 1,000-ppm groups,  and 30 rats/sex in the 10- and 100-
 ppm groups) were fed diets containing 0 (control), 10, 100, or  1,000 ppm technical grade simazine
 (96.9% pure), which corresponds to simazine doses of 0, 0.5, 5.0, and 50 mg/kg/day, respectively, for
 104 weeks (7 days/week) according to the schedule in Table V-3.
                                             V-10

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Simazine Criteria Document
           Table V-3.  Experimental Design for the Chronic/Carcinogenicity Study With Rais
Dose group
(ppmVphase
Control
",


' 10



100



1,000

-


Chronic •


Carcinogenicity
Chronic


Carcinogenicity
Chronic


Carcinogenicity
Chronic


Carcinogenicity

No. rats
Males
10
10
20
• 50
10
20

50
10
20

50
10
' 10"
20
50

Females
10
10
20
50
.10
20

50
10 " :
20

50
10
10b
20
50

Time of sacrifice • '
(52 weeks) Least number '•••
Males Females Of dose weeks
10 10 . 52
52 + 52-week recovery
104
104
10* 10 52 :'
104 i;
3 ' '
'.104 l
1.0 101 52 '' . A
' '• .104 ' M
i
104
10 101 52
52 + 52-week recovery
104
104
>•**•*;
•Only nine animals were actually sacrificed in these dose groups.
These 10 animals were excluded from analysis.

SOURCE:  Adapted from McCormick et al. (1988).
                                           V-ll

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Simarine Criieria  Document
    All animals were observed daily for clinical signs of toxiciiy and mortality. Food consumption and
body weights were determined weekly for study weeks  1  through 13, biweekly  for smdy  weeks 14
through 25, and monthly thereafter.  Water consumption was measured at study weeks 1, 2,' 53 'through
64, and 102.   Hematological, blood biochemistry, and urinalysis determinations  were carried out as
indicated in Table V-4.

   , The mortality rate  was' high (40-79%) between study  weeks 53 and 106 (terminal sacrifice) for all
groups.   The survival rate in females  in the 1,000-ppm group was  20% as .compared  with  34% in
controls; for males, the survival rate was higher than that of controls (60% versus 39%). Mean body
weights for males and  females in the 1,000-ppm group were significantly (p <0.0l) lower than those of
controls from day 7 through  termination of the study (day  728).  For the 100-ppm group, female rats
had significantly (p 
-------
       inff Criteria Document
             Table V^t.  Schedule for Hematology, Blood Chemistry, and  Urinalyses for the
                                  Chronic/Carcinogenicity Study With Rats
No. nu used for clinical
lab determinations!
Dose
group (ppts)
Baseline*
Control

10 .'
100

1.000

- NO;
M
20
to
20
.20
. 20

io
20
nil
•••WaBt
F
20
10
20
20°
20

10
20
Week of
ucnfice
•1
105-106
105-106
105-106
105-106

105-106
105-106
Haruiolog
M
10
10
to .
10
. 10

-to •
10 . .
r1
F -
10
10
to *
,10' -
aio
• •
to ':
10
|iocfl
M
' 10
10
10
10
10*
. - -
* 10'
10
on.*
F
10
10
10
10
10
a
10
10
Uriaalyserit
M
10
10
10
. • 10
10
> .
' • 10
10

F
to
10
10
10
10
<7
80'
10
•Aaimaii from the caicissf enicity pluat were wed Tor Qtett deiennioaaoDi u tin flnai sunpUng pehod ia
 order io luve lO/ieVgrovp.            '                          '      '    :
*AMlyiet wen conducted pradoM (lest weel^ -1) on baeline taiouto: al weeki 25 and M. T7 aad 78. ud 104
 on tainuli Jitigoed to toe 104-week chronic phue; and u week! 52, 65 ud 66, and 78 and 104 on tntmaU
 anigoed to (be recovery pbaie.         .
•Bueline aniroalt included tO/sex for hentiology ud 10/iez for b|oebeau»ry ud wiaalyiu.

SOURCE: Adapted £rom McCormidc ei aL (1988).
                                                         V-13

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      Simazir.e Criteria Document
      group males, significantly lower valuestwere seen on day 537 for MCV and on days 537 and 725 for'
      MCHB.

         The only changes in clinical chemistry indices attributable to simazine treatment were the depression
      of glucose levels in females at all  time points of sampling.  The lower glucose values, however, might
    . be the indirect result of depressed body weights  in this group.  Glucose depression was also seen with
      the recovery group females at all time points tested except day 725.  Most of the urinalysis indices were
      comparable in the control and treated groups in  both sexes.

         Significant (p <0.05 to 0.01) decreases in absolute organ weight were observed for the brain in males
      receiving 1,000 ppm at the 52-week sacrifice, for the heart in males receiving 1,000 ppm at the terminal
      sacrifice, and for the liver in females'receiving 1.000 ppm  at the 52-week  sacrifice.   In male rats
      receiving 1,000  ppm,'the relative weights for the brain, liver, and testes were significantly (p <0.05)
      higher than those of controls  at the.52-  and 104-week sacrifices. In females receiving' 1,000 ppm,.tH&
      relative weights  of the brain,  heart, adrenal, kidney, liver, and ovaries at the 52-week interim sacrifice/
      were significantly higher than those of  controls; for  kidneys,  a significant  difference was also seen at
      the 100-ppm dose.  Additionally, the relative weights of the heart, kidney,  and liver were significantly
      higher than controls in the 1,000-ppm  group at the  104-week terminal sacrifice. Significantly lower
      organ-to-brain weight ratios were observed for the heart in males receiving  1,000 ppm at the 104-week
      sacrifice and for the liver in females receiving 1,000 ppm at the 52-week sacrifice.  The organ weight
      changes mentioned above were not thought to indicate a major  lexicological  concern, since such changes
         -•
      were .not. associated  with concomitant clinical chemistry changes or changes in  macroscopic or
                     •    9     '
" {  / fpticroscopic.pathology in the  same organs. In this study, the LOAEL of 5.3 mg simazine/kg/day in rats
     »'-' -••••-.**.                    »
      Vas based on body_weight depression and depression of hematology indices (RBC, HGB, and HCT) in
     • female rats.,.,TheTICi^Hrwas found to be'0.52 mg simazine/kg/day.                        .4^.,-.-

         Gysin and Knusli (1960) reported that simazine, fed to  rats for 2 years' at  1,10, or 100 ppm in the
      diet, produced no apparent signs of systemic toxicity (no details given). These diets correspond to doses
      of about 0.05, 0.5,  or 5 mg/kg/day, assuming daily consumption of 40 g feed/kg bw.

         The U.S. EPA (Anderson and Copley, 1988) evaluated a 1-year chronic feeding study (McCormick
      and Green, 1988, for Cifaa-Geigy) in beagle dogs approximately 6 months old (males weighing 7.5 to
      9.1 kg, females  weighing 6.5 to 8.2 kg). Technical grade simazine of unspecified purity (the same batch

                                                  V-14

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Simazine Criteria Document


of simazine was reported to b^ ?/.5% pure in a previous study) was included in the diet at 0, 20, 100,
and 1,250 ppm, which corresponds to simazine doses of 0, 0.76, 3.6, and 45 mg/kg/day for females 'and
0,0.68, 3.4, and 43 mg/kg/day for males. The diet with or without (control) simazine was'administered
to randomly grouped (four per group) animals for 52  weeks (7 days/week).  Animals were inspected
daily for signs of toxicity and mortality.  The animals were weighed weekly for the first 12 weeks and
monthly thereafter. Mean daily dietary consumption was determined. Efficiency and compound intake
were calculated from the food consumption and the body weight gain data.  Hematology and clinical
chemistry analyses were carried out on blood samples  collected from.all animals before treatment and
at days §6,177, and 359. Urinalyses were carried out on usually catheterized urine from predosing and
at 86,177, and 359 days. All animals were sacrificed ori schedule and-subjected to gross pathology and
histopathology.       '   ..'                  .                         .

    Apparent dose-related fecal changes such as diarrhea,  discoloration and presence  of blood, and
infrequent emesis were observed:  Cachexia* was noted  in one male/and one female dog receiving 1.25Q
ppm from study'weeks 14 through 22.  No deaths occurred during the study period. Male body weigh;.
gain was depressed at the 1,250-ppm dose level during  most  of the study but not at the end of the study.
                  i                                         .                    •
Body weight gain in females dosed at 1,250 ppm was depressed through study week -36, when females
appeared to begin gaining body weight.  Almost all animals gained a normal amount of weight at the
100-ppm dose level. Food consumption was reduced  in females receiving 1,250 ppm during the first
20 .weeks of study; otherwise, no reductions in food intake were observed for males and females.  Food-
efficiency appeared to be compromised only in females receiving 1,250 ppm during the first 12 weeks *
of the study.

    In males receiving 1,250 ppm, a transient nominal decrease was observed in RBC and HGB at study
days 86 and 177, and a significant  (p <0.05) depression in.HCT was observed at study day 86 when
compared with controls. The platelet counts were significantly (p <0.05-0.01) elevated in the 1,250-ppm
males at the end of 86 (142%), 177 (170%), and 359 (155%) days of dosing. In the 1,250-ppm females,
a significant (p <0.05) transient decrease in RBC, HGB, and HCT occurred at study days 86 and 177.
MCHB was slightly but significantly elevated after 359 days of dosing, but MCV, MCHB, and MCHC
values were within the control range.  The study indicated that the hematologic effects were secondary
to body weight decrements, but additional data  were not provided as evidence.
                                            V.-1S

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  Sinmir.e Criteria Document


     Random  changes  occurred  in clinical chemistry  indices at the  1,250-ppm dose level, but they
  appeared to be neither consistent nor dose related. This was true for elevation in serum sodium in male
  dose groups  at 177 days and for decreases in serum calcium in all female dose groups at 86 days.
  Urinalyses did not reveal any treatment-related changes.  No dose-related effects occurred in organ
  weights, organ-to-brain weight ratios, and organ-to-body weight ratios despite some observed nominal
  increases" in  adrenal  (130%),  kidney  (111%), and  livet  (108%)  weights, and decreases  in the
.  thyroid/parathyroid (60%) and spleen (69%) weights in males dosed at 1,250 ppm.  Similarly, in females
..  dosed  at l;250 ppm, some nominal weight increases were noted in the  adrenal (129%), liver (104%),
 •and thyroid/parathyroid (114%), and weight decreases were  noted in the spleen (81%).  Neither gross
  nor microscopic dose-related effects were observed in the above organs and tissues.
                                                                                        3
•  ,   This' study indicated  a NOAEL of 20 ppm or  0.76 mg simazine/kg/day for females or 0.68 mg
  simazine/kg/day for males.   These Values  are quite close,.and,  therefpre,  a  mean of 0.72 rhg
  simazine/kg/day can t>e considered as the NOAEL. Based on decreased body weight gain, and decrease?
.  in  RBG, HGB,  HCT, and a nominal  increase in platelet  counts  in  tcmales,  idO ppm or 3.6 mg
  simazine/kg/day is indicated .as  the LOAEL.                          .

     In a 2-year chronic feeding study in beagles, simazine SOW (80%) was administered in the  diet at
  15,150, and  1,500 ppm (Woodard Research Corporation, 1965b, as cited in NAS, 1977). These levels
  correspond to doses of about 0.35, 3.5, or  35 mg/kg/day, assuming  1 ppm is. equivalent to 0.025
  mg/kg/day (Lehman, 1959).  Animals receiving the high dose (1,500 ppm) developed a slight thyroid
  hyperplasia, and several dogs fed 1,500 ppm had  slight  increases in serum alkaline phosphatase and
  serum glutamic-oxaloacetic transaminase activities. Minimal data were reported on which to base an
  evaluation of a dose-response relationship. U.S. EPA (1985) evaluated this study (submitted by Ciba-
  Geigy Chemical Corp. for registration), in which all dogs survived the  2-year period with no signs of
  toxieity due to dietary administration of simazine at 15,150. and 1,500 ppm, except for a net weight loss
  of 6%  at 1,500  ppm and reduced weight gain at 150 ppm  during the  first year of the study.  These
  differences could not be accounted for, since the  reports lacked individual feeding records. Neither
  chronic toxieity  nor oncogenic potential could be determined from this study.

     Clayton and Clayton (1981) reported that when simazine was fed to dogs for 2 years,  no adverse
  effects were  seen at the 12- and 120-ppm dietary concentrations; however,  slight signs of toxieity were
  noted at the  1,200-ppm dietary concentration.  Other  data were not presented.

                                              V-16

-------
                                                 EFFECTS


                                                                                                   i
              A two-generation reproductive toxicity study (Ciba-Geigy Corp., 1992) was carried out in Sprague-
          Dawley rats (CRL: COBS CD (SD) BR) using  simazine technical  (96.5% pure) in the die:.  Two
                                                                                                   ,l
          successive  generations  (F0  and  F.)  of  rats (30/sex/group)  were fed  continuously  throughout
          premating/rest, mating, gestation, and lactation periods with the herbicide at 10,100, and 500 ppm levels
         in the diet: a control group received the diet without simazine. The F, generation of all four groups fijad
         two matings, which produced F^ and Fa offspring. In the 10 ppm groups, neither adverse clinical signs,
                                                                                                   ;i
        toxicologic effects nor mortality were observed. Treatment-related transient reductions in body weight
        gains (about 6-13%} but no mortality were observed in the 100 ppm F0 and F, parental animals. In die
        500 ppm groups, significant reductions in mean body weight gains were noted during the feeding periocs
       in parental males (approximately 27% for F0, and 8-51% for F: generations) and in parental females
       (approximately 38% for F0? and 32-75% for F. generations).  A comparison between  treated (F0 and F»
      progeny)^ and  control groups revealed no treatment-related effects on mating, duration  of gestation,;
      fertility, and mating and gestation indices.  Similarly, no differences in die treatment-related effects, were;,

                                                                                               i    ,'
      noted in any of the measured reproductive parameters (the mean number of implantation sites and viable i:
                           *                              '                                     i     !
     rjeonates,  the mean number and percentage post-implantation loss and the-mean number and percentage ij
     of still births) between treated and control groups.  There were no treatment-related effects on F, and f
     Ffc pup survival, weights, sex ratios, or malformations at any feeding level.

        A significant increase (approximately 11 %) in mean relative testicuiar weight in F0 males was related
    to a treatment-related  decrease in body weight gain in  these animals since meari absolute testicular
   weights were unaffected.  Mean absolute and relative ovarian weights in F0 females were not affected
   by treatment. Also, slight increases in F, relative testicular weight and Fl  mean relative ovarian weights
   were attributed to treatment-related decreases in mean terminal body weights.  Treatment-related effects
  were not noted following gross necropsy or histopathological examination of tissues in any of the created
  groups.  Based on the results of this study, simazine technical was not considered t^ffecr reproductive
  performance in rats.  The-reproductive NOAEL was suggested as 500 ppm and the parental NOAEL as
  10 ppm.  The dietary level of 500 ppm simazine was considered equal to or greater than the maximum
 tolerated  dose, based on die significant reduction in body weights observed at this level.

    Woodard Research Corporation (1965a) conducted a mree-generation reproduction study in rats and
found no adverse effects on the development or reproductive performance of the animals, A group of

                                            V-17

-------
          Simazine Criteria Document
          40 weanling Charles River albino rats (20 males, 20 females; F, generation) were fed simazine SOW
          (80%) in the diet at 100 ppm (approximately 5-mg/kg/day, assuming a daily  consumption of 50 g
          feed/kg bw).  Another group of 20 males and '20 females served as controls. After exposure to the test
          compound for 74 days, the two sexes were paired and allowed to mate for 10 days. The Fu generation
         • and litters were examined for the number of live  pups and the mean litter weights, number of stillborn,
          and physical condition of test animals.  After weaning the first litters, parents were remated as different
          pairs  and F,b litters  were obtained and examined.  The Ft  animals were divided into two test groups.
          One group was. fed  simazine at 50 ppm (approximately 2.5 mg/kg/day), and the other group was  fed
          simazine at 100 ppm (approximately 5 mg/kg/day).  After 81 days of dosing, the animals were mated,
          and Fi and Fa litters 'were produced.  Fa"rats were mated to produce Fj, and F3b litters. At weaning,
          the F3, litters were sacrificed and the F3b Utters were necropsied,  Liver, kidney, and heart weights were
          determined for two animals/sex/litter at weaning.  These tissues plus the spleen, adrenal, thyroid, gonad,
          and bone marrow were preserved.  Tissues from one animal/sex/litter were examined histologically.
                                                0  ,
              Data from this. 1965 study were reevaluated by the U.S. EPA in 1989 (Spencer and Copley, 1989).,
          It was pointed out that the purity of simazine  used in this study  was 8(5%.  The test diets were not
                                                                        <>. •
          assayed for homogeneity orjpj the actual amount of simazine present in the diet.  No statistical analyses
         ..•'•."                                                         «
          of the data were performed.. Food and "water consumption data were not compiled. Daily observation
^•>c°.':-   rf .parental -afl&fiB&^alled no clinical signs of toxicity.  However, body weight gains were reduced •
 •     ---' "      £ _r. •'"•"''' '
              teJ^ generation in males but not in females. Reduced gains were observed as early as the second
               .  •" °                                            °
          'jpek of, exposure to 100 ppra,simazine.  A 9.5% reduction in weight  gain was seen by week 14 when
          compared with controls.

              In the Fls males, 7.7  and 15.6%  reductions in weight were observed by weeks 16 and 26,
          respectively, in the 100-ppm group as compared with controls. At 16 weeks, however, a greater change
          was observed in the 50-ppm group than in the 100-ppm group, in that the percentage of weight loss was
           18.7 and 22.7, respectively, as compared with controls. In Ftb females, the weight loss was about 7.5%
          by study week 8 in both the 50- and 100-ppm groups. Males in  the Fa generation appeared to be more
           affected by the 50-ppm dose diet than by the 100-ppm dose diet.  About 10% weight loss occurred at
           50 ppm by week 17 of the study! F^ females exhibited weight losses of about 10% by week 11 of the
           study at both dosages.  The adult animals were not weighed during gestation or lactation.
                                                       V-18

-------
Simazine Criteria Document
    Absolute organ weights and organ-to-body weight ratios were similar to those of treated animals and
controls.  However, a dose-related increasing trend in absolute  liver weights was noted  in the F3b
weanling males.  No gross  lesions  relating to dietary exposure to simazine were observed, although
necropsy results were sparsely reported.  No histopathqlogy wa.> reported in adult males, including 3/10
in the iOO-ppm Fib group that appeared to have been sterile in their mating efforts. No histopaihologic
changes were observed in one male and one female examined in each litter of the F3b pups as^compared
with controls. Treated pup mean weights (g/pup/litter) a: birth  did not vary significantly from controls
in any generation.

    The Agency concluded  (Spencer and  Copley,  1989)  that this study suggests a parental toxicity
NOAEL of <50 ppm and a LOAEL of 50 ppm based  on reduced weight gains  in males  during the
premating periods.  A reproductive toxicity NOAEL/LOAEL could not be determined based on lack of
evaluation of apparent sterility in the F,b generation males.  Up to 33% of the'potential parental stock
                                                                                   f        ••
at 100 ppm did not produce a pregnant female in two successive breeding sessions.    •  • • ';   .  l
                .                "                             '    *                       • *
    Chen (1981) studied the teratogenic effects of simazine in rats.  The herbicide was administered by
gastric intubation to pregnant rats from gestation days 6 through 15  at dose levels of 78,312,1,250, and
2,500 mg/kg bw/day. Ossification of the sternum and cranium was delayed at all four dose levels.  At
doses of 312-mg/kg and above, body weight gain was inhibited in the dams, the number of live fetuses
wa°s reduced, and the rate of fetal resorptions increased.  At the higher dose  level  (2,500 mg/kg),
simazine caused delayed fetal development.   The author concluded that simazine was toxic to rat
embryos but was not teratogenic.
    The U.S. EPA (Anderson and Copley, 1988) evaluated a maternal and developmental (embryo/fetal)
                              *
toxicity study carried out in Crl: COBS CD SD BR rats (Mainiero.et.al., 1986). The age of die animals
at mating was not specified, but weights were in the range of 200 to 350 g. Technical grade simazine
of unspecified purity (the same batch was specified as 97.5% pure in a previous subchronic study in
dogs) was administered by gavage in 2% carboxymethylcellulose in a volume of 10 mL/kg. Simazine
was administered on gestation days 6 through 15 in doses of 30, 300, and 600 mg/kg/day. Animals were
observed twice daily for signs of toxicity and mortality, and weighed on gestation days 0 (the day sperm
were detected), 6,  10, 14, 18, and 20; carcass weights (body:weight minus uterus and contents) were
determined on gestation day 20.  Feed consumption was reported between gestation days 0 and 5, from
gestation days 6 through 15, on days 16/17,  and days 18/19.  Relative  efficiency of feed utilization  was
                                             V-19

-------
 Simazir.e Criteria Document


 calculated as mean daily body weight gain (kg) divided by mean daily feed consumption (g). Dams
 .were killed on gestation day 20 by carbon dioxide asphyxiation and subjected to gross pathology. Fetal
- examination consisted of evaluation of viable litter size, live and dead fetuses, and postimplantation loss.

     Significant (p <0.5-0.1) reduction in body weights compared with vehicle-created controls occurred
 on gestation days 10 (93%), 14 (89%), and 18 (94%) in rats dosed at 300 mg/kg/day; at 600 mg/kg/day,
 the corresponding values were 90, 86, and 94%, respectively.  The carcass weight was  decreased 93 and
 91% in the 300-  and 600-mg/kg/day dose groups.  Body weight gains were significantly less (p <0.05)
 than controls from gestation days  6 to 10  and 10 to  14, and greater (p <0.05)  than controls from
    •                                                        a                               •
 gestation days  14 to 18 and 18 to 20 in animals dosed at 300 and 600.mg/kg/day.  Food consumption
 was significantly (p <0.05-0.01) decreased  from gestation days  6 through 15, and  increased during
 gestation days  15 through 19 at both the mid and high doses. The relative efficiency of food utilization
 apparently decreased at the mid and high doses for gestation days 7  to  10, and a nominal decrease
 occurred for days 7 to 10 at .the 30-mg/kg/day dose level, and for days 11 to 14 at the 600-mg/kg/day"
 dose level. Treated and control rats gained  the least body weight and consumed -the  least  food during
 gestation days 6  through 10.

     Gross pathology of dams demonstrated no dose-related effects.  No dose-related effects were noted
 for mean fetal weights, viable litter size, live and dead fetuses, .postimplantation loss,  and visceral
                           *
 malformations or variations. Some random variations occurred, including short or absent renal papillae,
 dilated uterus, dilated trachea,  and  mottled livers.  Skeletal effects that occurred in fetuses on a litter
 basis in a dose-related manner  but that were reported as not significant were unossified presphenoid at
 600 mg/kg/day and additional lumbar vertebrae/centra at 300 and 600 mg/kg/day. Additionally, the total
 number of variations were* nominally increased and appeared to  be dose-related in fetuses at all dose
 levels. Significant
 •(p <0.05-0.01) fetal skeletal variations that occurred at 300 and 600 mg/kg/day were as follows: head
 incompletely ossified, unossified teeth, unossified centra/vertebrae and/or additional, rudimentary ribs,
 and unossified stemebrae.  These  results suggested a NOAEL of 30 mg/kg/day for developmental
 (embryo/fetal) toxicity and a LOAEL of 300 mg/kg/day. No malformations were reported. A maternal
 toxicity NOAEL of 30 mg/kg/day and a LOAEL of 300 mg/kg/day and higher for decreased maternal
 body  weight and body weight gain, food consumption, and efficiency of food utilization  were also
 identified in this study.
                                              V-20

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 Simazine Criteria Document


    In evaluating this study, the U.S. EPA (Anderson and Copley, 1988) pointed out that most of the
 parameters associated with fetal toxicity frequently occur in association with maternal toxicity and some
 might disappear if the fetuses were followed after birth.  The statistically significant increase in fetuses
 but not in litters for unossified stemebrae at all dose levels may not be real, especially at 30 mg/kg/day.
                        *                                   o                               .
 The increase in unossified stemebrae at 30 mg/kg/day resulted from a high non-dose-related incidence
 of unossified stemebrae 5 and 6 in  all  groups, and a low incidence  for stemebrae 1,  2, 3, and 4.  A
 comparatively higher incidence of unossified stemebrae 2 and 3 resulted in a doss-related manner at 300
                                                                        '     '
 and 600 mg/kg/day and in the apparent dose-related response seen at the 30-mg/kg/day dose.  For this
.study, the high incidence in historical controls, the failure of the effects to be statistically significant in
                                         i
 litters, and the interaction of the incidence of the"six stemebrae and the unossified stemebrae in animals
                                              *                              *
 dosed at 30 mg/kg/day are not  considered to be an effect.  The Agency has requested additional
 information related to the mode of preparation of the test material, the appropriate particle sizes and the
•distribution of panicle sizes of the test material suspended in the vehicle, the analyses data on samples
 of dosing suspensions, the purity .of the test material, and the source of the test animals in the study}.
 The study  was graded as being supplementary because of the additional information requested.      -
                    »    "     .       ^                              *   .               -.
    »                                         •
    «
    iSimazins (technical grade), was administered by gavage to a group of 19 New Zealand White rabbits
 (2.5 to 4;5 kg) at daily doses of 5,75, or ?00 mg/kg for days 7 through 19 of presumed gestation (Ciba-
 Geigy, 1984). The herbicide was delivered as.a suspension in 3% comstarch containing 0.5% Tween-80.
 A control group was given  the vehicle  only. One death was observed in  each group; however, death
 of the low-dose dam was assumed to be due to a dosing accident and not to the compound-related drug.
 Maternal toxicity at 75 and 200 mg/kg was indicated by abortions, tremors, decreased motor control and
 activity, ataxia (in one high-dose animal), few or no stools, anorexia, weight loss, and decreased body
 weight gain,  Embryotoxicity was  not observed,  but fetal  toxicity, which was believed to be the
 consequence of maternal toxicity, was evident in the intermediate and high-dose groups as indicated by
 decreased  numbers of viable fetuses.  Fetal toxicity at 200 mg/kg also was reflected by reduced fetal
 body weights, increased occurrence  of floating  and fully formed ribs, and decreased ossification of the
 patellae.   No malformations  were associated  with any dose level of simazine, and at 5 mg/kg the
 herbicide exerted neither toxic nor teratogenic effects.   The authors concluded that at doses of 75
 mg/kg/day and higher, simazine was very toxic to  fetuses and dams but was neither embryotoxic nor
 teratogenic.
                                              V-21

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  SLmazine Criteria Docu.-r.ent


     Tnis teratology study has been reviewed by the U.S. EPA (Mount/on et al., 1986, for Ciba-Geigy),
  and adequate explanations for some of the issues were sought. Ciba-Geigy has responded to these issues
  by supplying additional information and satisfactorily addressing the issues raised in the review. First.
  while the study reported statistically significant decreases in the mean number of live fetuses at the 75-
  and 1100-mg/Tcg dose levels, the data presented for the groups dosed at 0 (control), 5,75, and 200 mg/kg
  were 7.9, 8.4, 6.8, and 7.8, respectively. The mean of 7.8 in the 200-mg/kg group was not significantly
  different from  the mean of 7.9 for the control group.  Furthermore, the differences between the control
 •group and  the 75- and 200-mg/kg groups  were demonstrated only, in a nonparametric analysis of
  covariance  with the number of implantation  sites as a covariant. Thus, no significant differences were
  found to  exist between controls and treated groups jor  this reproductive index.   Second, the EPA
  reviewers  questioned  the validity 'of calculating the  pre-  artd postimplamation  loss  rates.  They
  determined that instead of calculating loss  percentages per dam and .then deriving mean group loss
  percentages, the  investigators should  have calculated group percentages of pre- and postimplantation
  losses 'using the total .numbers of corpora  lutea,  implantations, and viable fetuses per dose group.1
                                                         a                       »
  However, the Ciba-Geigy group explained to the satisfaction of the Agency'that if one failed to use the
' - line/-as. the excsrimental unit, the latter procedure would lead to the incorrecj assumption that there can
c
  be no influence of litter ifize upon fetal and embryonic viability, and that the fetus, instead of the, liner.
                           5                                                .
  is the experimental-unit.
                  •                                 ft
     The Agency concluded that based on this study, the teratogenic NOAEL for simazine in rabbits was
  up to and including 200 mg/kg when administered by gavage on days 7 through 19 of gestation. At 200
  mg/kg, a significant reduction in mean fetal weight and a significant increase in the incidence of skeletal
  variations in fetuses were observed. The fetotoxic NOAEL was 75 mg/kg. The  maternal NOAEL was
  5 mg/kg based on decreased body weight gain, tremors, and increased abortions at 75 and 200 mg/kg.

      Dshurov (1979) reported that repeated oral administration of simazine to sheep (6.0 mg/kg for 142
  days or 25  mg/kg for 37 to  111 days) caused necrosis and dystrophy  in the germinal epithelium of the
  testes and disturbances of spermatogenesis.

      No treatment-related developmental effects were observed  by Newell and Dilley (1978) in the
  offspring of pregnant rats exposed to simazine  at 0, 17,  77, and 317 mg/mj via inhalation for 1 to 3
  hours/day on days 7 through 14 of gestation.
                                               V-22

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 Simazir.e Criteria Document


     Dunachie and Fletcher (1970) tested 25 herbicides, including simazine, for their toxiciry to chicken
 embryos, using an egg-injection technique. Except for feather blanching caused by some of the substitute
 phenoxy-acids, no teratogenic effects were found.  According to the authors, simazine was difficult to
 dissolve and to keep in solution; concentrations up to 300 ppm (in 75% acetone) did not produce any
 significant toxic effect. •

i'                 ."    .                                              '                          *
     The effect of simazine on the gonads of chick and quail embryos in in vitro culture has been studied
 by  Didier (1974).  In these studies, gonads of  9-day-old embryos were  explanted  on a  medium
 containing simazine.  After 5 days, the male gonads of the chick embryos displayed sterility or reduced
 fertility, while the ovaries reacted by a Joss of cortex.  In the quail embryos, the germinal material of
 the testes was destroyed and the gonocytes of the  ovary degenerated.

 D.  MUTAGENIC1TY  .
n.     •  '        ' '
                                                                        .                      ^
                                                                                               «.
     Relatively few studies  investigating  the genotoxic potential  of simazine have appeared in the
 published literature. This section includes the published experiments as well as a series of unpublished
 assays that were performed to meet U.S. EPA registration requirements. These are categorized into gene
       *
 mutation assays (Category 1), chromosome aberration assays (Category 2), and studies thar assess  other
 mutagenic mechanisms (Category 3),  The findings are discussed below.
                             o

 1. Gene Mutation Assays (Category I)

     a. Microorganisms, reverse and forward mutations
     Anderson et aL (1972) evaluated the mutagenicity of 110 herbicides including simazine by measuring
 reversion  frequency of histidine independence  in  eight unidentified mutant strains  of Salmonella
 typhimurium. Small crystals of simazine were applied directly to the surface of each plate after the top
 agar layer (containing the bacteria) had solidified. Further details were not reported.  Simazine did not
 cause a measurable  increase in reversion frequency in comparison with controls.

     Simmons et al. (1979) evaluated the mutagenicity of 18 pesticides including simazine by measuring
 reverse mutation  frequencies in S. rfphimurium and Escherichia colL  Simazine was negative in both
 tests.  Experimental details were not reported.  Simazine also elicited negative responses when tested
                                              V-23

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Simazir.e Criierla Document


for mutagenicity in 5. yphimurium (Commoner, 1976), E. coli, mdSerratia marcescens (Fahrig, 1974).
Details of the experiments were not reported.     '     ' '

   Eisenbeis y. al. (1981) tested the mutagenic" activity of 20 herbicides including simazine in five
mutant strains of S. typhimurium (TA 1535, 1537,  1538,  98, and 100) with and without a rat liver
microsomal preparation. Simazine (tested at full strength, details hot reported) did not produce an
increase in the number of revenant colonies per plate in comparison with controls.

   Nishimura et al. (1982) evaluated the mutagenic activities of 25 pesticides, including simazine, in
the Ames Salmonella microsome assay. S.ryphimurium strains TA98 and. TA 100 were tested both with
                                                                                   i
and without S-9.mix prepared from phenobarbital-induced rat livers. Simazine'did not elicit mutagenic
                                      '             •                        •*
responses in TA98 or TA100, either with or without the S-9 mix, over a wide dose range up to the fatal
dose. The results were reported for only one dose level, i.e., 1.0 umoVplate.          . •  ' "  '    .

    Plewa et al. (1979) repotted moderate positive mutagenic responses withjriazine herbicides in tests'
with 5. typhimurium. and Saccharomyces cerevislae, but no details were provided.   .

    (3. Gene mutations in mammalian cells

    Waters et al.  (1982)  reported positive results for simazine in a mouse lymphoma  assay.  Other
information was not available.

    Murnick and Nash (1977)  employed three assays to test simazine  for mutagenicity in Drosophila
melanogaster, Assays for dominant lethal mutations, sex-linked recessive lethal (SLRL) mutations, and
chromosomal nondisjunction, loss, and breakage  were .performed on male flies treated by injection or
by larval feeding of the herbicide simazine as Princep SOW (80% simazine, 20% inert ingredients).  The
feeding experiments used the highest concentrations of simazine (0.4 and 0.6%) found to be nonfatal to
larvae.  The average  dose given to  adults by injection was  0.074 mg simazine  solution (5.9 x 10"* g
simazine).  Simazine significantly increased the rate of dominant iethals; however, the reduction in egg
hatch was probably due to physiological toxicity to sperm. The herbicide did not significantly increase
sex-linked recessive Iethals, X or Y loss, XY nondisjunction, or partial loss of the Y chromosome when
 administered by larval feeding. However, when administered by injection in the adult males, simazine
                                             V-24

-------
 Simazins Criteria Document
 induced SLRL at a rate of 0.34%. which differed significantly from the control (p 
-------
 Simnzine Criteria Document
    c.  Sister chromatid exchange ("SCE1
                *
    Ghiazza et al. -(1984) investigated the induction of sister chromatid exchange in cultured human
 lymphocytes  exposed to simazine concentrations of 0.001, 0.01, and 1 ppm. An increase in 5CE per
 cell was found in cultures treated' with 1 ppm simazine (5.09 ± 1.19) as compared with the control (3.51
 + 1.14). 'The authors stated that these differences were statistically significant (p = 0.001).       .

    Waters et ai. 0982) reported that simazine was negative in a sister chromatid exchange study. Other
 information was not available.

    d.  Cell transformation»

    The U.S. EPA Gene-Tox Program reported that simazine was positive in cell transformation assay
                  **                                *                   «                     *.
 with hamster embryo cells.  Other data were not available.

 E.  CARdNOGENICITY                                            '

    Innes et al. (1969) performed a screening study on the tumorigenicity of 130 pesticides and industrial
•compounds, including simazine.  Beginning at 7 days of age, two hybrid strains of mice (C57BL/6 x
 C3H/Anf and C57BL/6 x AKR) were  administered simazine by stomach tube at 215 mg/kg/day. After
 weaning. 18 mice of each sex of each strain (total of 72)  were  fed 603 ppm simazine in the diet (215
 mg/kg/day for 4-week-old mice) ad libitum for 18 months.  The tumor incidence in mice treated with
 simazine was not significantly higher than that of controls (p <0.01) for any type of tumor.

    Simazine did not produce inflammatory, degenerative, proliferative, orneoplastic lesions in male and
 female Swiss Charles River mice fed simazine at dietary levels of 15,1,000, or 3,000 ppm for 17 to 22
 months (Ciba-Geigy,  1980a).   This  corresponds  to  average daily doses  of 1.5, 100, and  300 mg
 simazine/kg/day, assuming daily consumption of 100 g feed/kg bw.  Gross pathological examinations
 performed  on all 480 animals  (including 120 controls) showed no dose-related or  compound-related
 effects of simazine. However, this study was performed by IBT and is considered to be invalid.

    An oncogenicity study  in Crl:CDl(ICR)BR mice fed  technical grade  simazine in the diet  at
 concentrations of 40,1,000, or 4,000 ppm for 95 weeks (Hazelette and Green, 1988) did not reveal any

                                             V-26  -

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Simazine Criteria Document                                                              ~


evidence of carcinogenicity, suggesting that  the compound was not oncogenic in mice.  In fact, the
incidence of malignant lymphomas was higher in control females than in dosed groups. However, all
values were within the range of incidence found in other laboratories. There were several nononcogenic
effects; these effe'cts and^exgenmental details were discussed  in Section V.B.2 of this document.  .    -
                                                     *                %
    Low-level carcinogenicity was noted in  white rats and CC57 mice following chronic feeding or
dermal application of simazine (Pliss and Zabezhinsky, 1977).  Simazine also produced sarcomas at the "
site of subcutaneous, injection in both rats arid mice.  Tumors occurred in 30% of the experimental
animals following an 18-month latency period.  Details as to "tumor types and«control incidences were
not presented in this abstract. Thus, the study has no value in assessing carcinogenicity.
                                                      o                '
                                                                              »
                         '  *                                                   .
  . The U.S. EPA.(Ioannou and Copley, 1988) has evaluated the histopathological data from a 2-year
 #                                           .
feedlng/oncogenicity study in Sprague-Dawley albino rats (McCormick et al., 1988, for Ciba-Geigy).
The experimental details  and results of hematology, clinical chemistry, urinalysis. and gross and
histopathology as related to nononcogenic responses .for technical simazine were presented in Section
                 o
V.B.2 of this  repprt  Neoplastic and nonneoplastic  lesions encountered in male and female rats are
                            O          ,    i
summarized in Tables. V-5 and V-6, respectively. Based on the statistical evaluation of the neoplastic
findings described below, simazine technical  was considered to be onogenic in female Sprague-Dawley
rats receiving  100 and  1,000 ppm (including  the formation of mammary gland carcinomas).  Simazine
technical also appears to increase the induction of liver tumors in male rats receiving 1,000 ppm.

    Tumor incidences presented in Tables V-7 to V-13 in the following section are for the number of
tumor-bearing animals/number of animals at risk (excluding animals that died before the observation of
the first tumor or animals not examined), and the percent incidence is denoted in parentheses.  The
significance of trend is denoted in the "control" columns, and the significance of pairwise comparison
with contro4is denoted in the "dose level" columns.

      1. Female Rats
         *•  Mammarv gland - In female rats in the main study, there was  a statistically significant
             increase in the incidence of mammary carcinomas  in the mid- and  high-dose  groups
             compared with controls. A statistically significantly higher incidence of fibroadenomas
             was seen in the high-dose  group.  Table V-7 summarizes the incidence  of these  lesions
             when calculated separately for  female animals that died (or were sacrificed moribund) or
             animals that survived to terminal sacrifice.
                                             V-27

-------
Suukzine Criteria Document
           Table V-5. Summary of Histopaihological Lesions in Male, Rats Fed Diets
                              Containing Simazine for 2 Years
Dose (com)
Histopathological observation1
c
Neooiastic lesions
t t , ,
.Adrenal - Cortical adenoma • .
.
Kidney -.Adenoma •
- Carcinoma (primary) _ .
Liver - Hepatocellular adenoma
- Hepatocarcinoma
- Combined adendma and/or
carcinoma
thyroid - C-cell adenoma
- C-cell carcinoma
- Combined adenoma and/or
carcinoma
Pituitary • Adenoma
Nonneoolastic lesions
*
Adrenal • Cortical hypertrophy/
cystic degeneration
- Focal cortical
hyperplasia
Liver - Hyperplasia
Pituitary - Hyperplasia
Skin - Chronic lymphocytic
inflammation
Testis - Focal interstitial
cell hyperplasia
Thyroid - Focal interstitial
cell hyperplasia
0
•
0/69b -

' 0/70 *
.0/70. ; /
'""1/70
0/70
1/70
0
. 2/70
2/70-
4/70

42/69 -

7/69

2/69

2/70
12/69
1/70

6/70

7/70

10

•0/70
•
0/70
• 0/70.
1/70
2/70
3/70 . .

7/69
1/69
8/69

47/70

4/70

2/70

0/70
14/70
0/68

2/70

3/69

100
»
1/69 '
o
0/70
0/70
0/70
4/70
4/70'

. 5/69
1/69
6/69

47/70

6/69

3/69

0/70
10/70
1/69

8/70

5/69

1,000
•
' 2/69 '

1/70 ..
. 2/ZO
3/70
3/70
6/70

6/70
3/70 l
9/70

.38/70

13/69

.7/69

0/70
15/70
5/70

11/70

9/70

•Main study only (interim sacrifice and recovery groups not included).
"Number of rats* were specified observation/total number of tissues examined.

SOURCE:  loannou and Copley (1988).
                                           V-28

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Simazine Criteria Document
            Table V-6. Summaiy of Histopathological Lesions in Female Rats Fed Diets
                                Containing Simazine for 2 Years
0
Histopathological observation* '
• Neoplastic lesions
Mammary - Adenoma
- Carcinoma
- Fibroadenoma
Pituitary - Adenoma
" - Carcinoma
Kidney - Adenoma (tubular)
Nonneoplasric lesions
Mammary - Cystic glandular
hyperplasia
Pituitary - Hyperplasia
o
Kidney - Hydronephrosis
• Epithelial hyperplasia
pelvic
Adrenal • Focal medul hyperplasia
Liver - Hematopoiesis
Spleen - Hematopoiesis
Thyroid - Focal interstitial
cell hyperplasia

0

2/70" '
14/70 -'
22/70'
62/70
1/70
e?
0/70

51/70
2/70
3/70
0/70
0/70
0/70
3/70
0/70
Dose
10

4/70 .
13/70 '
27/70
57/70
3/70
0/70 '

50/70 .
6/70
0/70
0/70
4/70
1/70
1/70
2/70
(ppm)
100

1/70
19/70*
19/70
60/70
0/70
0/70

53/70 ..
- 3/69
0/70
0/70
3/70
1/70
1/70
2/70

1,000

5/70
35/70***
40/70** • '
57/70
6/70
2/70 i
i
65/70***
2/70
6/70
3/70
3/70
5/70*
10/70*
4/70
"Main study only (interim sacrifice and recovery groups not included).
"Number of rats were specified observation/total number of tissues examined.
*, **, ***rndicate significance at p <0.05, p <0.01, and p <0.001, respectively.

SOURCE:  loannou and Copley (1988).
                                             V-29

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Simazine Criteria .Document
           , Table V-7. Incidence of Mammary Gland Tumors in Female Rats Fed Diets
                               Containing Simazine for 2 Years
Dose (ppm)
Sacrifice schedule .
Early deaths (prior to
terminal sacrifice)

Scheduled sacrifice.
(104 weeks)

Combined incidence
*
• ,
Lesion
Adenoma*
Carcinoma
Fibroadenoma
Adenoma
Carcinoma
Fibroadenoma
Adenoma
Carcinoma
Fibroadenoma
0
2/46"'
10/46
14/46
0/24
4/24
8/24
2/70
14/70
22/70
10
. 3/47
9/47
• 17/47 3
1/23-
4/23
10/23
4/70 '
13/70
27/70
100
1/53
12/53 .
. 11/53
0/17
7/17
8/17
1/70
19/70*
19/70
1,000
4/56
28/56**
28/56**
1/14
7/14* .
12/14*
5/70.
. 35/70** "
40/70** *
"Number of animals .with specified observation/total number of tissues examined.
*,**Indicate significance at p <0.05 and p <0.01, respectively.

SOURCE:  loannou and Copley (1988).
                                                                                    0 '
                                             V-30

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Sirnazine Criteria Document
       Table V-8.  Incidence of Mammary Gland Tumors in Sprague-Dawley Rats Fed Simazine
         for 2 Years—Female Mammarv Gland Tumor Rates and Peto Prevalence Test Results


Tumor type •

-^Adenoma/
fibroadenoma
.~;
.* ..
• j


Carcinoma.

*
Adenoma/
carcinoma




0


23/89
(26)
p = 0.0689
. «


16/89- •
(18)
p <0.0001**

39/89
(44) .
p <0.0001**

a
10


20/78'
'(26)
• p= 0.302 :



13/80'-
(16)
p = 0.4740

33/80
(41)
• p = 0.4064
•j
Dose (ppm)
•
100
*
'- .•
11/71
(15)
' p m 0.177
.• . ,
. 0
4
. 20/75b. '
(27)
p = 0.0392*

31/75
(41)
p = 0.2229


i,odb '

0
21/75 •
0 (28)
p = 0.123

a '

• 40/78
(51)
. p<0.0001*
i
61/78
(78)
p<0.0001**
'First adenoma observed at 48 weeks at the 10-ppm dose level.  First
 fibroadenoma observed at 52 weeks at the 0-, 10-, and 1,000-ppm dose levels.
bFirst carcinoma observed at 48 weeks at the  100-ppm dose level.
 *, **Indicate significance at p <0.05 and p <0.01, respectively.

SOURCE:  loannou and Copley (1988).
                                             V-31

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Simazine Criteria Document
            As  the statistical analyses carried out by the authors  for different tumors in male and
            female rats were determined to be inadequate, further statistical, evaluation for the major
            rumors listed in Tables V-5 and V-6 was conducted by the Agency.  Data presented in all
            tables following are the combined tumor incidences from the 52-week' interim sacrifice and
            the  104-week study.   The incidence of mammary tumors in- female rats is presented in
            Table V-8.

          ." These results indicated a statistically significant dose-related trend in mammary carcinomas •
            and in combined adenomas and carcinomas. The incidence of mammary carcinomas was
            statistically  significantly  increased  in the mid- and5 high-dose groups -cempared with
            controls; also the incidence of combined adenomas and,carcinomas was significantly higher
            in the highest dose tested (HOT) compared.-with controls. Mammary carcinomas {in the
            main study—^104-week sacrifice) contributed, according  to the  authors, to the increased
            mortality in the high-dose group animals (1,000 ppm). A higher incidence of mammary .
            carcinomas was also seen in the recovery study (52 weeks of treatment, wish 1,000 ppm
            followed by 52  weeks  of recovery),  1/10  versus 4/10,  for the control and HDT,
          •  respectively.
                  1        *  *                                            .
            In female rats, the incidence of hyperplastic changes (cystic glandular hyperplasia) in the
            mammary gland was very statistically significantly higher than controls in the HDT-. TM§
            •finding  corroborates  the observed high incidence of tumors in the HDT.  It'.is generally
            understood that the higher tumor incidence correlates directly with a higher incidence of
         *  hyperplastic changes.'       • •           ,                »
                                    a-
         b. Pituitary gland -  In female rats,  the incidence  of pituitary (pars distalis) carcinoma was
            found to be higher than controls in the HTD.  The authors reported that this incidence was
            .statistically significant with the Peto life-table method of analysis used.  The incidence of
            adenomas was found to be extremely high in all groups,  but the authors reported that the
            incidence in the mid* and high-dose groups was statistically significantly increased when
            Peto's method was used for analysis (when contribution  to death is considered).  Further
            statistical analysis of these tumors (total tumor analysis) indicated, as shown in Table V-9,
            that the  incidence of combined adenomas/carcinomas in the mid-  and high-dose groups was
          o statistically  significantly higher than controls with a significant dose-related trend.
                                                                                            >.
            The authors reported that these tumors (adenomas and carcinomas) were considered to tfc
            fatal "by virtue of their size and compression of the mid-brain," and thus contributed to the
            decreased survivability of the mid- and high-dose group  females.  Although these tumors
            (adenomas/carcinomas) were of approximately the same numerical incidence in all groups
            (treated and control), examination of the Kaplan-Meier survival curves indicates that the
            onset of these tumors is 4 to 15 weeks earlier in the mid-  and high-dose groups as
            compared with the control and low-dose groups.

            For further evaluation of these rumor data, the Agency requested historical control data and
            the  results  of the immunocytochemical staining  of  the pituitary for identification of
            prolactin.                                                .               <&

         c. Kidney - A very low incidence of tubular adenomas was seen in female rats receiving the
            high dose  (Table V-10).   The low incidence of this tumor does  not appear to be
            biologically significant.
                                             V-32

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Simazine Criteria Document
      2.  Male Rais
         c.
 *                •                         «            .
 Liver - In male rats, the incidence of hepatocellular adenomas or carcinomas was very low
 in ail treated and control groups (0-5%).  As shown in Table V-ll, the incidence  of
 combined adenomas and carcinomas was* statistically significantly higher in the high-cose
 group compared with controls, possibly suggesting oncogenic potential of simazine to male
 rats.

 The incidence of hyperplastic changes, however, was very low in the control (2/70) and
 nonexistent in the treated groups (0/70, see Table V-5)

 Thvroid - Although  the incidence of combined thyroid £-cell adenomas  and carcinomas
 was numerically higher in .all treated groups as compared with controls, as shown in Table
 V-12, there was no significant dose-related tren,d or statistical significance between treated
 and control groups.   The incidence of hyperplastic changes  was comparable to  the
. incidence"of tumors  for each group.
     »
 Kidnev - A very low incidence of tubular adenomas and carcinomas was seen in male rats
 (Table V-13). A statistically significant dose-related trend was observed for the incidence
 of carcinomas  as  well as  the incidence of combined adenomas and carcinomas. As in
 female rats, the very low incidence of this rare rumor in male rats does not appear to be
 of biological significance.
                                             V-33

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Simazir.e Criteria Dccumeni
         Table V-9. .Incidence of Pituitary Tumors in Sprague-Dawley Rats Fed Simazine
                 for 2 Years—Female Pituitary Gland Tumor Rate, Fatal Tumor
                     .    . Analysis, and Generalized K/W Test Results

Tumor type
Adenoma


Carcinoma


Adenoma/.
carcinoma •
a


0
73/89
(82.0)
. p = 0.0033**
1/73
-.. -0-4)
p = 0.0010**

74/89
(83.1)
p = 0.0005**
•
10 . .
0
57/80
(71,2) .
p =» 0.9944
3/61 •
(4.9)
p = 0.2351

' 60/80
' (75.0)
p = 0.8351 -
Dose (ppm)
•100 •
63/771 " ' '
(81.8)
p = 0.020.6*
0/52 '
-(0.0) '
- p = 0.4545

63/77.
(81.8)
p..= 0.025,1*
*
1,000 • •
61/79
(77.2)
p = 0.0033**
6/53b
(11-3)
p = 0.0153*

67/79
(84.8) •
p = 0.0005**
'First adenoma observed at 35 weeks at the 100-ppm dose level
bFirst carcinoma observed at 72 weeks at the 1,000-ppm dose level
*, **Indicate significance at p <0.05 and p <0.0l, respectively.

SOURCE:  loannou and Copley (1988).
                      .    .

                         "*
                                         '   V-34

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Sirrozine Criteria Document
         Table V-10.  Incidence of Kidney Tumors in Sprague-Dawley Rats Fed Simazine
              for 2 Years—Female  Kidney Tubule Tumor Rate, Cochran-Armitage
                          Trend Test, and Fisher's Exact Test Results
                                                      Dose (ppm)
Tumor type
                         10
                     100
                       1,000
Adenoma
  0/74
' (0.0)   •
p * 0.0042**
  0/62   -
  (0.0)
p = 1.0000
    0/54
  .  .(0.0)'
'  p = 1.0000
  2/551
  (3.6)
p = 0.1799
'First adenoma observed at 71 we.eks at the 1,000-ppm dose level  No
 carcinomas were noted.
**Indicates significance at p <0.01.

SOURCE:' loannou and Copley (1988).
                                            V-35

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Simazins Criteria Document
          Table V-ll.  Incidence of Liver Tumors in Sprague-Dawley Rats Fed Simazine
              for 2 Yean—Male Liver Tumor Rate, Cochran-Armitage Trend Test,
                               and Fisher's Exact Test Results
• . •• .& -
Tumor type "
» .
Adenoma


Carcinoma

.*
Adenoma/
carcinoma


•
0 .
1/88
(1.1)
p = 0.0824
0/88
(0.0)
p. = 0.2169

1/88
(1.1)
p = 0.0643

10 .
2/79" '
. (2.5)
p • .0.4594
* m
2/79
(2.5)
p = 0.2223

4/79
(5.1)
p = 0.1519
Dose (ppm)
100
0/80
(0.0)
p = 0.5238/
4/80"
(5.0)
p = 0.0494*

4/80
(5.0) .
p = 0.1554
+ ,
• 1,000
a ...
3/80 ' ' .
" C3.8J
•p- 0.2752
3/80
(3.8) .
p = <0.1058
i.
6/80
(7.5)
p = 0,0449*
"First adenoma observed at 52 weeks at the 10-ppm dose level.
"First carcinoma observed at 99 weeks at the 100-ppm dose level.
*Indicates significance at p <0.05.

SOURCE:  loannou and Copley (1988).
                                           V-36

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Simazine Criteria Document
        Table V-12. Incidence of Thyroid Tumors in Sprague-Dawley Rats Fed Simazine
        for 2 Years—Male Thyroid C-Cell Tumor Rates and Peto Prevalence Test Results

9
Tumor type
Adenoma


Carcinoma


Adenoma/
carcinoma


-

0
2/52
(4)
p = 0.3355
2/34
' (6)
p = 0.1762

4/52 ' -
(8)
p = 0.1924


10
7/52* '
(13)
p = 0.0606
1/31 •
(3)
p = 0.1082

8/52
(15)
p = 0.1965 •
Dose (ppm)

100
5/51
(10)
p F 0.1082
1/36
(3)
p = 0.2881*

6/51
(12)
p = 0.2261 .


1,000
'6/58
(10)>.
p = 0.0870
• 3/45"
'(7)
p = 0.4183
i
9/58 i
(16) •
p = 0.1505
"First adenoma observed at 89 weeks at theJO-ppm dose level.
"First carcinoma observed at 102 weeks at the 1,000-ppm dose level
*Indicates significance at p <0.05.

SOURCE:  loannou and Copley (1988).
                                           V-37

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Simazine Criteria Document
         Table V-13.  Incidence of Kidney Tumors in Sprague-Dawley Rats Fed Simazine
         for 2 Years—Male Kidney Tubule Tumor Rates and Peto Prevalence Test Results
                                                      Dose (ppm)
Tumor type
Adenoma


Carcinoma


Adenoma/
carcinoma


0
0/51
(0)
p = 0.0543
1/66
(2)
p = 0.0332**

1/66
(2)
p - 0.0056**
'' 10
0/46
(0)
p = 1.0000
0/62
(0)
p = 0.1660

0/62
(0)
p = 0.1410
100
0/48
(0)
p= 1.0000
0/64
(0)
p = 0.1821

0/64
(0)
p = 0.1721
1,000
1/57'
(2)
p = 0.5278"
2/656
(3)
p = 0.2091

3/65
(5)
p = 0.1087
'First adenoma observed at 92 weeks at the 1,000-ppm dose level.
The p values for adenomas were calculated using the Cochran-Armitage Trend
 test and Fisher's Exact test, since the Peto Prevalence method collapsed to
 one interval.
**Indicates significance at p <0.01.

SOURCE:  loannou and Copley (1988).
                                            V-38

-------
    In a 2-year dietary study (Hazleton Laboratories, 1960; NAS, 1977), simazine SOW (49.9% active
ingredient) was administered in the diet to Charles River rats at 0, 1, 10, and 100 ppm (expressed on
the basis of 100% active ingredient). These doses correspond to 0,0.05,0.5, and 5 mg/kg/day, assuming
daily consumption of 50 g feed/kg bw (Lehman, 1959). Thyroid and mammary tumois were observed
in high-dose females. Complete histopathological details were not provided, and statistical significance
was not evaluated. This study was not considered to be adequate for evaluation of carcinogenic potential
owing to high incidence of respiratory and ear infections  in all groups.

F.-  SUMMARY
 '£•
 '$-
    The acute oral LD50 estimates in rats, mice, rabbits, and birds are 5,000 mg/kg or higher, but a dose
of 500  mg/kg  has  been reported to be lethal in  sheep.  Pharmacotoxic signs in sheep included
incoordination, tremors, weakness, cyanosis, and clonic convulsions.  A single dose of 4,200 mg/kg
caused anorexia, weight loss, and some lethality in rats.

    Short-term oral administration of 500 mg/kg/day in rats resulted in lethality within 20 days. Doses
of 15 mg/kg/day in rats produced mild hepatic degeneration in 3 days, but this condition did not progress
with repeated dosing.

    In a 28-day oral toxicity study, simazine was fed to albino mice at dose levels ranging from 0 to
4,500 mg/kg/day. The animals were examined for gross pathology, food consumption, and body weight
at the end of 28 days.  No discernible toxicologic effects were noted in mice fed simazine up to 450
mg/kg/day. A NOAEL of 450 mg/kg/day has been identified from this study.

    Death occurred in Delaine sheep administered daily oral doses of simazine at 50, 100, or 400
mg/kg/day for 31,14, or 9 days, respectively. Toxic symptoms produced consisted of muscular spasms,
fasciculations, stiff gait, and increased breathing.

    Dermal application of simazine  to rabbits at doses  up to 1 g/kg/day for 21 days did not show
 systemic  toxicity, dermal irritation, or dermal sensitization.

    No treatment-related deaths were observed in rats fed simazine at dose levels up to 343 mg/kg/day
 for 13 weeks, but significant reduction in body weight and organ weight were observed in both males
                                             V-39

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Simazir.e C.-:er.j Document


and females at ail dose levels. Other parameters affected included decreased erythrocyte and leukocyte
counts and other hematology  indices in all treated groups, lowered blood glucose, sodium and calcium,
high cholesterol, and low liver function.  Histology revealed a dose^related increase in the incidences
of renal calculi and renal epithelial hyperplasia, which was significant in the 4,000-ppm males. Based
on these findings, a NOAEL  of less than 10 mg/kg/day was identified.

   The- same protocol  was  used  to study the  effects  of simazine in dogs, and  a  NOAEL  of.
                                                a                 .            •       •
 '  9 ,                 •       .                     •           '  -
approximately 7 mg/kg/day was  obtained based on reduced serum  albumin  levels, increased serum
             B
globulin, and elevated urinary ketone bodies at the 2,000-ppni dose level (64 to 65  mg/kg/day).  A 6-
month study in rats and guinea pigs indicated .that a dose of 20 mg/kg/day was without effect, but a dose
of 100 mg/kg/day suppressed normal weight gain and caused an increase in leukocyte count. Lower
                                    . *
doses (1.4 to 25 mg/kg/day) have been reported to cause hyppthyroidism in sheep following daily doses
for 63 to 142 days.           •'.:.''•
           '                                  .         •         "                          »
             •    '                             '              a                  .
    In a chronic oral toxicity  study, simazine was fed to Charles  River CD-I mice for 17 to 22 months
 c                      '          °                                          •   .          • '
at dose.levels ranpng from  0 to 300 mg/kg/day.  A decline HI survival rate and body  weight was
observed in animals receiving the high dose  (300 mg/kg/day). No treatment-related effects were noted '
with regard to gross pathology. However, this study  was determined to  be invalid. A detailed 95-week
       •     f
chronic feeding study in  Crl:CDl(ICR)BR mice revealed a NOAEL of 6 mg simazine/kg/day and a
LOAEL of 150 mg/kg/day based on decreased body weight gain. The body weight reductions were
significant (p <0.01) at dose levels of 150  and 600 mg/kg/day.  Hematocrit and hemoglobin values
tended to be lower in the high-dose animals  than in controls. Amyloidosis  was more pronounced in all
dose  groups than in controls; this  and other incidental effects  were not considered to be compound
related.                  :

    In a 2-year feeding study with rats, doses up to 100 ppm in the diet (about 5  mg/kg/day) did  not
produce apparent systemic toxicity.  A  recent 2-year chronic feeding study in Sprague-Dawley rats
revealed a NOAEL of 0.52 mg simazine/kg/day and a LOAEL of 5.3 mg/kg/day based on decreased
body weights and on hematology indices (red blood  cells, hemoglobin concentration, and hematocrit in
females).

    A 1-year chronic feeding study in beagles revealed a NOAEL of 0.72 mg/kg/day (0.76 and 0.68 mg
simazine/kg/day for female  and male dogs, respectively) and  a LOAEL of 3.6 mg/kg/day based on

                                             V-40

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 Simazine Criteria Document
 and females at all dose levels.  Other parameters affected included decreased erythrocyte and leukocyte
   *  •                                              -i          * •
.counts and other hematology indices in all treated groups,.lowered blood glucose,'sodium and calcium.
 high cholesterol, and low liver function. Histology revealed a dose-related increase in the incidences
 of renal calculi and renal epithelial" hyperplasia, which was significant in the 4,000-ppm males.  Based
 on these findings, a NOAEL of less than 10 mg/kg/day was identified.

    The same protocol  was used  to  study  the effects  of  simazine  in dogs, -and a NOAEL of
 approximately 7 mg/kg/day was obtained  based  on reduced  serum> albumin levels, increased serum
•«                •                                   .                           "     '    *
 globulin, and elevated urinary ketone bodies at the 2,000-ppm dose level (64 to 65, mg/kg/day),  A 6-
 month study in rats' and guinea pigs indicated that a dose of 20 mg/kg/day was without effect, but a dose
 of 100 mg/kg/day suppressed notrrial weight gain-and caused an increase in> leukocyte count.  Lower
 doses  (-1.4 to 25 mg/kg/day) have been reported to cause hypothyroidism in sheep following daily doses
 for 63 to 142 days.                          .          '••••'     •     ."•-,'
                                                                    °
    In a chronic oral toxicity study, simazine' was  fed to Charles River CD-I mice for 17 to 22  months
                   6                 '                   *     •'    -       '
 at dose levels ranging from 0 to 300 mg/kg/day.  A decline in survival rate and body .weight was
 observed, in animals receiving the high dose- (300 mg/kg/day).  No treatment-related effects were noted
 with regard to gross pathology. However, this study was determined to be invalid,  A detailed ^5-week
                                                                  a •
 chronic feeding study in Crl:CDl(ICR)BR mice  revealed a NOAEL  of 6 mg simazine/kg/day and a
 LOAEL of 150 mg/kg/day based on decreased body weight gain.  The body weight reductions were
 significant (p <0.01) at dose levels  of 150 and 600 mg/kg/day. Hematocrit and hemoglobin values
 tended to be lower in the high-dose animals than in controls.  Amyloidosis was more pronounced in all
 dose groups  than in controls;  this and other incidental  effects were not considered to be compound
 related.

    In a 2-year feeding study with rats, doses up to 100 ppm in the diet (about 5 mg/kg/day)  did not
 produce apparent systemic toxicity.  A recent 2-year chronic feeding study in Sprague-Dawley rats
 revealed a NOAEL of 0.52 mg simazine/kg/day and a LOAEL of 5.3 mg/kg/day based on decreased
 body weights and on hematology indices (red blood cells, hemoglobin concentration, and hematocrit in
 females).
     A 1-year chronic feeding study in beagles revealed a NOAEL of 0.72 mg/kg/day (0.76 and 0.68 mg
 simazine/kg/day for female and male dogs, respectively) and a LOAEL of 3.6 mg/kg/day  based on
                                             V-40

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Sirnazine Criceria Document
decreased body weight gain, erythrocyte count, and hemoglobin concentration, and a nominal increase
in platelets in females.  In a 2-year feeding study in dogs, doses up to 150 pprn'(about 3.5 mg/Tsg/day)
were without effect. However, a dose 'of 1,500 ppm (about 35 mg/kg/day) resulted in a slight thyroid
hyperplasia  and a slight increase in serum alkaline  phosphatase  and serum  glutamic-oxaloacetic
transaminase activities.                   .      '              •

    A two-generation reproductive toxicology study in rats fed simazine technical in the diet at 10, 100,
and 5QO ppm revealed no. adverse-clinical signs, treatment-related toxic effects, or mortality at the
10 ppm level.  A transient treatment-related decrease in body weight gain was observed in the parental
animals at the  100 ppm level.  However, at 500  ppm, treatment-related adverse effects were noted in
                                            .       0
FO and F! parental animals  and included reduced body, weight gain, slightly ingreased mean relative
testicular weights  as well  as mean relative ovarian weights in F; females. No treatment-related effects  '
                  '-                                       t  *
were observed on reproductive parameters, F, and.F^ pup survival, weights, sex ratios,'or malformations
              *                   t                   •»'          *                           ',
at any 'dose level  Remarkable gross or hi|topathoiogical effects were not observed in any of the
                    "                    °     . '
examined generations at any dietary level.  Based on significant weight gain reductions at 500 ppnvthis
          •                               a
dose was considered equal to or greater  than the maximal tolerated  dose.  This study suggested a
reproductive NOAEL of 500 ppm and a- parental NOAEL of 10 ppm.

    In a three-generation reproduction study with Charles River rats continuously fed  simazine SOW in
the diet at 50 (2.5 mg/kg/day) or 100 ppm (5 mg/kg/day), a parental NOAEL of less  than 50 ppm and
a  LOAEL of 50 ppm were identified based on reduced weight gain  in males during the premating
periods.  The reproductive toxicity NOAEL/LOAEL could not be determined in  this  study because of
the lack of evaluation  of  apparent sterility in FIb generation males.
    In a teratology study with rats, simazine administered in high doses (78 to 2,500 mg/kg/day) during
gestation days 6  through 15 delayed fetal development  and was embryotoxic  but not teratogenic.
Another teratology study in Crl:COBS CD SD BR rats administered simazine by gavage in doses of 30,
300, and 600 mg/kg/day on gestation days 6 through 15 revealed developmental and maternal toxicity
NOAELs of 30 mg/kg/day and LOAELs of 300 mg/kg/day based on skeletal variations (incomplete
ossification) in fetuses and decreased body weight gain in dams. At the LOAEL, several developmental
variations were observed, but the U.S. EPA has not considered them to be a compound-related effect.
The study  was graded as  supplementary  because additional  information  was requested.  Similarly,
maternal and fetal toxicity were observed in  rabbits given oral doses of 75 or 200 mg simazine/kg on

                                             V-41

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            Criteria Document
   gestation days 7 through  19.  The  teratogenic .N'OAEL was 200 mg simazine/kg.  At this dose, a
   significant reduction in mean fetal weight and a significant increase in the  incidence of skeletal
   variations in fetuses were observed.  The fetotoxic NOAEL was 75 mg/kg. The maternal N'OAEL was
   5 mg/kg, which was based on decreased body weight gain, tremors, and increased abortions at 75 and
   200 mg/kg. Doses of 6 or 25 mg/kg/day for 142 diiys  or 37 to 111 days, respectively, caused decreased
 6-spermatogenesis in sheep.   -'                             ".                           "...."

      Most  tests  of mutagenic potential for simazine have been negative,  both in  procaryotic and
   eucaryotic systems. The herbicide was nonmutagenic in the Ames Salmonelia/micTOsomt assay,' mitotic
                 *                                                                   ...
   recombination assay in Stocpharomyces, and unscheduled DNA  synthesis assay in human fibroblasts.
   However, it induced sex-linked recessive lethal mutations in Drpsophila and sister chromatid exchanges
'  in human lymphocytes. .              '            '                             -       •
           «    . i           .                                              *
               • •  •  •'                        '           '   v                        "
      No increases in tumor frequency and/or neoplastic lesions were observed in C57BL/6 x C3H/An£
          t                    '   '
   and C57BL/6 x AKR mice dosed with simazine at 215 mg/kg/day. by stomach tube for 18 months.  A
.  17- to 22-month feeding study IH Swiss Charles River mice (Ciba-Geigy, I980a) indicated no  dose-
   ;elated adverse effects for simazine, but this study, performed by 1ST, is considered to be invalid.  A
   95-week oral toxicity/oncogenicity study in Crl:CDl mice receiving diets containing 40,1,000, or 4.000
   ppm simazine revealed no evidence suggestive of oncogenic activity.  In the 2-year carcinogenicity  study
   in Sprague-Dawley rats fed dietary simazine at 10, 100, and 1,000 ppm for 104 weeks, simazine was
   found to be oncogenic in female rats, inducing  mammary tumors at dose  levels  of 100 ppm (5.3
   mg/kg/day) and 1,000 ppm (63.1 mg/kg/day).  In  male rats, simazine appears to induce the formation
   of liver tumors at the 1,000-ppm dose level (45.8  mg/kg/day).
                                               V-42

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 Siraazine Criteria Document


                            VI.  HEALTH EFFECTS IN HUMANS' •

 A. CLINICAL CASE STUDIES                "

    No reports of toxicity resulting from oral ingestion of simazine by humans were located. Yelizarov
 (1977) reported that simazine and propazirie caused acute and subacute dermatitis in 124 workers who
 had" close contact with the herbicides in the U.S.S.R.  In subacute cases, pale pink erytherna and slight
 edema of the skin, lasting 3 to 4 days, Were observed.  Symptoms of acute cases usually lasted 7 to 10
 days  and included erytherna and edema as well as a number of small vesiculopapular elements  that
 sometimes produced dermatitis bullosa.

 B-. EPIDEMIOLOGICAL STUDIES

    No epidemiological studies of simazine exposure were located in the literature.    .    '        .l
           «                                                            *.'"'''
. C. HIGH-RISK POPULATIONS      .                .  .                             ' '

                                               o
    No data were located regarding differential sensitivity of different human subpopulations.

 D. SUMMARY

    Almost no information is available regarding simazine toxicity in humans. One study reported acute
 and subacute dermatitis in wo±ers at plants manufacturing simazine.                            ^
                                            VI-1

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 Simazine Criteria Document
                             .VH.  MECHANISMS OF TOXIQIY

    Very  little infonnation was found on the mechanism  of simazine-induced toxicity in animals.
 Lefalova et al.  (1983) reported that terbutylazine and simazine inhibited the activity of plant, animal, and
 yeast alcohol  dehydrogenases in vitro.  The  character 6f inhibition for both herbicides studied in the
 reaction catalyzed by pea, liver, and yeast alcohol dehydrogenase was always noncompetitive toward
 ethanol and competitive with respect to nicotinamide adenine .dinucleotide.  Inhibition constants were
 about KT'to 10'5 M.            .                               ...

   • Myhr (1973). measured the toxic effect of eight pesticides on protein and RNA synthesis in HeLa
 cells. -The effect of a 30-minute exposure to pesticides on the incorporation rates of labeled amino acids
 into protein and labeled undine into RNA in HeLa cells was examined;  Simazine (0.35 mg/mL) had
                 ' . •       <           .'                      •                   «
 no effect on the incorporation rates.                 .                       .
. «         . -        *                                                                    *
                                                                                             i
                 8
    Atrazine, a structural analog of simazine, has been found  to interfere'with nucleic acid synthesis both,
 in vivo  in BALB/c mice and in vitro in ascites tumor cells (Walker et al., 1979). Similarly, arrazine has
 been found to inhibit glycogen synthesis following intraperitoneal injection 'in adult- female Sprague-
 Dawley rats in vivo and in isolated hepatocytes in vitro (Messner, 1979).
                                              VH-1

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Simazine Criteria Document
                     . QUANTIFICATION OF TOXICOLOGICAL EFFECTS

    The  quantification of  toxicological  effects  of a  chemical consists  of an  assessment of
noncarcinogenic and  carcinogenic  effects.  Chemicals that do not produce carcinogenic  effects are
believed to have a threshold dose below which no adverse, noncarcinogenic health effects. occur.' whereas
carcinogens are assumed to act without a threshold.               .    .
                                            i»
A.  PROCEDURES FOR QUANTIFICATION OF TOXICOLOGICAL EFFECTS       '   .

L Noncarcinogenic Effects     .              •                                     ----
    In the quantification of noncarcinogenic effects, a Reference  Dose (RfD),  formerly called the
Acceptable Daily Intake (ADI), is calculated.  The RfD is. an estimate of a daily exposure of the human
population that .is likely to be without appreciable risk of deleterious health effects, even if exposure}
•occurs over a lifetime.  The RfD is derived from a No Observed Adverse Effect Level (NOAEL) or
Lowest Observed Adverse  Effect Level (LOAEL), identified from a subchronic or chronic study, and
divided by an uncertainty factor  (UF). The RfD is calculated as follows:
                        RfD .  (NOAEL or LOAEL)  , _ mg/kg/day
                                 UncenimyFactors
    Selection of the  uncertainty factor to be employed in the calculation of the RfD is based on
 professional judgment while considering the entire data base of toxicological effects for the chemical
 To ensure that uncertainty factors are selected and applied in-a consistent manner, the Office of Science
 and Technology (OST), formerly Office of.Drinking Water (OD W), employs a modification to the guide-
 lines proposed t>y" the National Academy of Sciences (NAS, 1977, 1980), as follows:
         a
  * An uncertainty factor of 10 is generally used when good chronic or subchronic human exposure data
    identifying a NOAEL are available and are supported by good chronic or subchronic toxicity data
    in other species.
                                           vni-i

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Simazine Criteria Document


  •  An uncertainty factor of 100 is generally used when good chronic toxicity data identifying a NOAEL
    are available for one  or more  animal species (and human data are not available), or when good
    chronic or subchronic toxicity data identifying a LOAEL in humans are available.

  •  An uncertainty factor  of 1,000  is generally, used when limited or incomplete chronic or subchronic
    toxicity data are available, or when good chronic or subchronic  toxicity data identifying a LOAEL.
    but not a NOAEL, for one or more animal species are available.

    The uncertainty factor used for a specific risk assessment is based principally on scientific judgment,
               .-"-.'.'       .•            ' .      •
rather than scientific fact, and accounts for possible intra- -and intejrspecies differences.  Additional
considerations not incorpprated in the NAS/OST guidelines for selection of an uncertainty factor include
the  use of a less-than-lifetime  study for deriving an RfD, the significance of the adverse health effect,
and the counterbalancing  of beneficial effects,                               .     •
                                                                               4           «.
    From the RfD, a Drinking Water Equivalent Level (DWEL) can be calculated. The DWEL represents,
a medium-specific (i.e., drinking water) lifetime exposure at which  adverse, noncarcinogenic health
effects are not expected to occur. The DWEL assumes 100% exposure from drinking water. The DWEL
provides the noncarcinogenic  health effects basis for establishing a  drinking water standard.   From'
ingestion data, the DWEL is derived as follows:
                    DWEL
  RfD x (body weight in kg)
Drinking water volume in L/day
,_.  mg/L
where:                                                                                     ^
            Body weight = assumed to be 70 kg for an adult.
    Drinking water volume  = assumed to be 2 L per day for an adult.

    In addition to the RfD and the DWEL, Health Advisories  (HAs) for exposures of shorter duration
(One-day, Ten-day, and Longer-term HAs) are determined. The HA values are used as informal guidance
to municipalities and other organizations when emergency spills or contamination situations occur. The
HAs are calculated using a similar equation to the RfD and DWEL; however, the NOAELs or LOAELs
are identified from acute or subchronic studies.  The HAs are derived as follows:
                                            vm-2

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 Simazi-.c Criteria Document
                  (NOAEL or LOAEL) x (BW)
                "                    L/day)     '
    Using the above equation, the following drinking water HAs ire developed for noncaicinogenic
 effects:
                                                                                    o

    1. One-day HA for a 10-kg child ingesting 1- L water per day.  •
    2. Ten-day HA for a 10-kg child ingesting 1 L water per  day,
   . 3. Longer-term HA for a 10-kg child .ingesting 1 L water per day.
    4. Longer-term HA.for a 70.-kg adult'ingesting 2 L water per day.'  .
                          •"                                             *             *
                                  . "                    .   »•          -               '
    The One-day HA calculated for a 10-kg child assumes a single acute.exposure to the criemical and
 is generally derived from a.study of less than 7'days' duration. The Ten-day HA  assumes a limited^
                               o        a                      ,
 exposure period of 1 to 2 weeks  and is generally derived from a study of less than  30 days'-duration.
 ' '                     •                              «                                    .  *
 The Longer-term HA is calculated for both a 10-kg child and  a 70-kg adult and assumes an exposure
                                             »          ^
 period of approximately 7 years (or 10% of an individual's lifetime). The Longer-term HA is generally
.  •
 derived from a study of subchronic duration (exposure for 10% of an animal's lifetime).

 2.  Carcinogenic Effects

    The  EPA categorizes the  carcinogenic  potential of a chemical, based on the  overall weight of
 evidence, according to the following scheme:

  • Group A:  Known Human Carcinogen.   Sufficient evidence exists from epidemiology studies to-
               support a causal association  between exposure to the chemical and human cancer.

  • Group B:  Probable Human Carcinogen. Sufficient  evidence of carcinogenicity in  animals with
               limited (Group Bl) or inadequate (Group B2) evidence in humans.

  • Group C:  Possible Human Carcinogen.  Limited evidence of carcinogenicity in animals in the
               absence of human data.
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 Simazir.e Criteria Document
                                                    -
  • Group D:  Not Classified as  to Human Carcinogenicitv.  Inadequate human and animal evidence
               of carcinogenicity or for which no data are available.

  • Group E:  Evidencejjf Noncarcinogenfcity for Humans. .No evidence pf carcinogenicity in at least
               two adequa:e animal tests in different species or in both adequate epidemioiogic and
               animal studies.                 •                            •  •

    If toxicological evidence leads to the classification of the contaminant as a known, probable, or
 possible human carcinogen, mathematical models are used to calculate .the estimate of excess cancer risk
 associated with the ingestion of the contaminant in drinking water. The data used in these estimates
      o                 .                                      •                                •
 usually come from  lifetime exposure studies in animals. To predict the risk for humans from animal •
 data, animal doses must Jje convened to equivalent human doses.  This conversion includes correctipn
 for noncontinuous exposure, less-than-lifetime studies, and  for differences in  size.   The  factor that
                                                                              •«       .  '   *    '
•compensates for the size difference is the cube root of the ratio of the animal. and human bod/ weightsC
 It is assumed that the average adult human body weight is 70 kg and that the average water consumption
                           a                                                        "  «
'of an adult human is 2 liters per day.                           ',-.,''

    For contaminants with a carcinogenic potential, chemical levels are  correlated with a carcinogenic
 risk estimate by employing a cancer potency (unit risk) value together with  the assumption for lifetime
 exposure  via ingestion of water.  The cancer unit risk is usually derived from a linearized  multistage
 model, with a  95% upper confidence limit providing a low-dose estimate; that is,  the true  risk to
 humans, while  nc£. identifiable", is not likely to exceed the upper limit estimate and, in fact, may be
 lower. . Excess cancer,risk estimates may also be  calculated using other models such as the one-hit,
 Weibull, logit, and probit. There is little basis in the current understanding of the biological mechanisms
_ involved in cancer to suggest that any one of these models is able to predict risk more accurately than
 any other. Because each model is based on differing assumptions, the estimates that were derived for
 each model can differ by several  orders of magnitude.
    The scientific data base used to calculate and support the setting of cancer risk rate levels has an
 inherent uncertainty due to the systematic and random errors in scientific measurement. In most cases,
 only studies using laboratory animals have been performed. Thus, there is uncertainty when the data
 are extrapolated to humans. When developing cancer risk rate levels, several other areas of uncertainty
 exist, such as the incomplete knowledge concerning the health effects of contaminants in drinking water.
                                             vm-4

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      iive Criteria Document
 the 'impact of the laboratory animal's age, sex, and species; the nature of the target organ system(s)
 examined; and the.acruai rate of exposure of the internal targets in laboratory animals or humans. Dose-
 response data usually are available only for high1 levels of exposure, not for the lower levels of exposure
 closer to where a standard may be set.  When there is exposure to more than one contaminant, additional  ,
 uncertainty results from a lack of information about possible synergistic or antagonistic effects.

 B.  QUANTIFICATION OF NONCARCINOGENIC EFFECTS  FOR SIMAZJNE '    .

 1. One-dav Health Advisory

    The only study (except for LDJO/lethality studies) considered to be of possible use in ..the calculation
                                 *               *       '       -          •        a
 of a One-day HA value for simazine was a single-dose oral toxicity study in sheep (Hapke, 1968). The
 sheep were administered a single  dose of commercial  simazine (50% active ingredient),  by oral
                                                                c
 incubation, at dose levels of 200, 250, 500,  600, 630, 790, and 6,000 mg/Kg and observed for toxic
.effects for at least 4 weeks. No discernible effects were  noted  in the 200-mg/kg dose group. Slight
                                                      *
 •reduction in feed uptake," polydipsia, and apathy were observed in the 250-mg/kg dose group. A dose
 of 500 mg/kg was fatal to four 'out of six sheep.   A NOAEL  of 200 mg simazine (50%)/kg  and a
 LOAEL of 250 mg simazine (50%)/kg have been identified from this  study. These NOAEL and
 LOAEL values would  correspond to 400 and 500  mg/kg, respectively, if the active ingredients  were
 100% simazine. These are conservative estimates,  since Hapke  found sheep to be more susceptible to
 simazine than rats and  mice. This study, however,  was not considered to  be adequate for derivation of
 the  One-day HA value because the number of animals used was  low (two to  six/dose), and  no
 histopathology was performed.                                                              ...,
                                                                                           •,\
     Since no studies found in the literature were suitable for determination of the One-day or Ten-day.
 HA values for simazine, it is recommended that the Longer-term HA value of 70 ug/L be used as a
 conservative estimate of the One-day HA and Ten-day HA values.

 2.  Ten-dav Health Advisory

     Of several studies considered for calculation of the Ten-day Health Advisory, none was found to be'
 adequate.  Table VIII- 1 summarizes  the studies  considered  for calculation of the Ten-day HA for
 simazine.  The teratology study carried out by Ciba-Geigy (1984) in New Zealand rabbits was described

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Simazine Criteria Document
           Table Vm-1.  Summary of Candidate Studies for Derivation of the Ten-day
                               Health Advisory for Simazine
Specie)
Rabbit
'. .




.
Rat


'
' '







&




Rat

Mouse


Route
Gsvige
in 3%
com-
• lurch
* 0.5*
Tweea-.
SO
Gavage
in 2%
carbony
methyi-
eeliu-
lose











Oral

Oral


Exposure
Duration
Oayi 7
through
19 of
gestation



Days 6
through
15 of
gestation o













3 or 28
day*
28 days


Endpoinu
Reduced
mean body
weight.
increased
itcefetal
variations
at LOAEL
Reduced body
weight, in-
creased in-
cidences of
incompletely
ossified
head, urfoj-
itfled teeth.
unoisified
. ' centra/

vertebrae.
pnsphenoid.
and siemebrae. •
and/o; addi-
tional rudi-
mentary ribs
Liver
histopaihuiujiy
Body weight
' gross
pathology
NOAEL o LOAEL
(rag/kg/day) (mg*g/day) Reference
i 200 Ciba-Ceigy
(maumai) (matemaj (1984)
75 and fetal) • . ' •
(fetal)

••"-•'•'
' ." •'"'.'.
30 300.' Mauuero
(fetal) (fetal) eial. (19*6)
30 300- « '
(maternal) (mtumai) 3

a • •
.
,
•



» ^
to .•
' f

' ' •
— • 	 OledM-
Sloiwinska
<1?74)
450 — Ciba-deigy
(1976)

"Hn determined.
                                          vm-6

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 Sinazir.e Criteria Document
 in Section V.C of this document.  Pregnant rabbits were given, by gavage, simazine in doses, ranging
•from 5 to 200 mg/kg over days 7 through 19 of gestation.  Maternal toxicity was observe'd at 75 mg/kg
 as indicated by. increased abortions, tremors, decreased motor control activity, and decreased weight gain.
' Fetal toxicity was noticed at 200 mg/kg and was associated with reduced body- weights, increased occur-
 rence  of floating and fully formed ribs, and decreased ossification of the patellae. aAt the 5-mg/kg dose
.level,  simazine did not exert a toxic or teratogenic effect.  No malformations were associated with any
 dose level of simazine.  The maternal toxicity NOAEL of 5 'iflg/kg/day is, however,  higher than- the
                                               fl  •                                       a
 NOAEL of 0.72' mg/kg/day suggested in the 1-year study with dogs (McCormick et al., 1988) chosen
 for deriving the Longer-term HA.
                                                                        ">  *                 .
                                                                    o
     "n the teratology study described by Mainiero et al. (1986), rats were dosed by gavage with simazine
 in 2% carboxyrhethylcellulose vehicle on gestation  days  6  through  15  at doses of 30,  300, or 600
 mg/kg/day.  This study suggested a NOAEL and LOAEL of 30  and 300 mg/kg/day, respectively, for
 fetal toxicity based on increased incidence of developmental indices  such as head incompletely ossified^
.teeth unossified, central vertebrae unossified and/or additional, rudimentary ribs, presphenoid unossified,,
 and stemebrae unossified.   As mentioned in Section V.C, the U.S. EPA raised several issues such as
 those  concerning the role of maternal toxicity and its influence on fetuses, the non-dose-related  nature
 of the incidence of unossified stemebrae 5 and 6, the  higher  incidence of dose-related unossified
 stemebrae 2 and 3  at higher doses, the high incidence of unossified stemebrae in historical controls, the
 mode of preparation of the test materials, and the source of  test animals. For these reasons, and until
 more  information becomes available on the concerns raised, the NOAEL and LOAEL suggested  in this
 study have not  been considered for development of the Ten-day  HA value.

     The 3-  to 28-day oral toxicity study in rats by  Oiedza-Slotwinska (1974) was  not  selected  for
 calculation of die Ten-day HA value because the  animals were exposed to only one dose (15 mg/kg/day)
 for 3  or 28 days/ Focal lesions were observed in hepatic parenchyma  after the first 3 days, but the
 condition did not progress.  Since a wide range of doses was  not employed, a NOAEL or LOAEL could
 not be identified.

     A 28-day oral toxicity study in albino mice (Ciba-Geigy, 1976), which was described in detail in
 Section V.A.2, was not considered for calculation of the Ten-day HA value for a child because this was
 a range-finding study and did not include adequate histopathological evaluations.
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 Sumzine Criteria Document
 3. Longer-term Health Advisory
               «  ' A                            •  •
    The l^ear feeding study in dogs (McCormick and Green, 1988), described in Section V.B.2, was1
 considered suitable for calculating a Longer-term HA. In this smdy, beagle dogs were fed simazine in.
 the diet at dose levels corresponding to (£76,. 3.6, and 45 mg/kg/day for females, and 0.68, 3:4, and 43
                                                •'                    *«      .     »
 mg/kg/day for males, for 52 weeks. Detailed monitoring of food consumption, body weight, hema'tdlogy, .
 clinical chemistry, urinalysis, and gross and histopathology of organs/tissues was carried out. This study
 indicated a NOAEL  of 0.76 mg/kg/day for females and 0.68 mg/kg/day for males.. These values are
-close to each other, and the mean of 0.72 mg/kg/day is considered to be the NOAEL.  The NOAEL is
 based on decreases in body weight gain, red blood cells (RBQ, hemoglobin (HGB), hematocrit (HCT),
 and a nominal increase in platelet counts noted in females 'at the LOAEL of 3.6 mg/kg/day and in males
 ai 43 mg/kg/day.   ,    •

    Two other studies were also considered. The 13-week oral toxicity study in rats (Tai.et al.,  1985a^
                                                                               i
 did not determine a NOAEL.  The 13-week- oral toxicity smdy in dogs (Tal et aL,  1985b), which
 indicated a NOAEL of 200 ppm, was considered less appropriate than  the 1-year oral toxicity study in
 dogs (McConnick and Green. 1988).  The latter study was chosen for deriving a Longer-term HA.

    The NOAEL of 0.72 mg/kg/day in the dog is selected for use as the basis for calculating the Longer-
 term HA.  This value is also close to the NOAEL of 0.52 mg/kg/day  suggested in the 2-year chronic
 toxicity study with rats (McCormick et aL, 1988) described in Section V.B.2. The latter study, which
 has been verified  by the U.S. EPA,  is considered to be more appropriate for calculating the RfD.

    The Longer-term HA for a 10-kg child is calculated as follows:
Longer-tern HA  -
                   (OJ2
                                              *? - 0.072 mg/L  (rounded to 70 ug/L)
 where:
      0.72 mg/kg/day = NOAEL, based on adverse effects such as decreases in body weight gain, RBC,
                      HGB, and HCT, and a nominal increase in platelet counts at the 3.6-mg/kg/day
                      dose level in female dogs.
                      This NOAEL is also supported by the NOAEL of 0.52 mg/kg/day developed
                      in the 2-year chronic toxicity study in rats.
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 Simazine Criteria Document
               10 kg = assumed weight of a child.-
            *   '        •          "              .            '   • .    •
               .  100 = uncertainty factor, chosen in accordance with NAS/OST guidelines for use with
                      a NOAEL from an animal study.

             I  L/day = assumed water consumption of a 10-kg child.

     The Longer-term HA for a 70-kg adult is calculated as follows:    •      '
       Longer-tern HA  . (b'72 *&***> <70 ^ . 0.252 mg/L  (rounded to 300 ug/L)
             .  ' '              (100H2 L/day)                *
                         - ' •                                   '   •.
 where:-     "             .   .o  *   .

      0.72 rag/kg/day = NOAEL, based on adverse effects in -female dogs such as decreases in body,
             '   '      weight gain, RBC, HGB, and HCT,  and a nominal increase in platele; counts
                      at the 3.6-mg/kg/day dose level.          .              •  •'
  *                                                   *           •         *            *
                      This NOAEL is also supported by the NOAEL of 0.52 mg/kg/day developed.
                      in the '2-year chronic toxicity study in  rats. '
              • .           "   *                                     o                         *
               70 kg = assumed weight of an adult.
                             *                a
                                     a
          .  v-V  100 = uncertainty^actor, chosen in accordance with NAS/CST guidelines for use with
                      a NOAEL from ^n •animal study.

             2 L/day = assumed water consumption of a 70-kg adult.

     However, it is advisable that the Longer-term HA value  of 70 ug/L for a 10-kg child also be used
  as the Longer-term HA for value for a 70-kg adult, because the relative source contribution for longer-

  term dietary exposure for adults could not be determined from the available data at this time.
•4.  Reference Dose and Drinking Water Equivalent Level


     A carefully controlled and executed 2-year chronic toxicity study (McCormick et al., 1988) in rats
  was described in detail in Section V.B.2.   This study has been verified by the U.S. EPA  for
  determination of the RfD, and was considered to be most suitable for calculation of the DWEL.  In this
  study, the LOAEL was 5.3 mg simazine/kg/day, and at this level, depressed body weight gain and
  adverse effects on several hematological parameters were observed.  The NOAEL was 0.52 mg/kg/day.
  This NOAEL is also supported by the NOAEL of 0.72 mg/kg/day obtained in the 1-year chronic toxicity
  study in dogs (McCormick and Green,  1988), described in detail in Section V.B.2.
                                            vm-9

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Simazine Criteria Document
                                  o
    Table VDI-2 summarizes the studies considered for calculation of the Rfl>and DWEL for simazine.
                                                       *   '         ">
Ciba-Geigy (1980) reported a 17- to 22-month orii toxicity study with  mice.  This study was not
                                 '"                       ••"'•»•"
selected for calculation- of the DWEL because it  was declared invalid by EPA owing to inadequate.
                                                      »
laboratory performance by Industrial Bio-Test Laboratories, Inc.        ?           " '
   *                                     *
    A 95-week oral chronic .toxicity study in Cri:CDl(ICR)BR mice (Hazelette and Green, 1988) was
                           «               ,
also considered For developing the DWEL. The  LOAEL for this study was 150 rag simazine/kg/day
based on depressed weight gain, and the NOAEL was 6 mg/kg/day.  10 this study the irigestion period
was less, and the NOAEL is much higher than that obtained in the 2-year chronic study with rats. The
2-year oral chronic toxicity studies in rats (Gysin and Knusli, 1960) and dogs (Woodard Research
Corporation, I965b) were not selected because they lacked sufficient documentation on which to base
               4          "                   "                                         *
evaluation of dose-response. The 1-year chronic feeding study with dogs (McCormick and Green, 1988)
was considered more useful for calculating the Longer-term HA than for determination of the RfD, since
the study did not involve lifetime exposure to simazine. This study suggested a NOAEL of 0.76 mg/kg4
day for females and 0.68 mg/kg/day for males, and supports the NOAEL determined in the 2-year study,
with rats.

     The three-generation reproduction study with rats by Woodard Research Corporation (1965a) was
considered and evaluated by the U.S. EPA (Spencer and Copley, 1989) for derivation of the RfD and
DWEL for simazine.  Although this study  suggested  a  parental NOAEL of less than  50 ppm,
reproductive toxicity could not be assessed owing to lack of histologic evaluations in apparently sterile
males in the Flfc generation.  Up to 33% of the potential parental stock at 100 ppm (5 mg/kg/day) did
not produce a pregnant female in two successive breeding sessions. Additionally, tissues from the male
 and female parents were not examined histologically in any  generation.  The  parental NOAEL of
 <50 ppm (<2.5  mg/kg/day)  indicated in this study is  higher than the  NOAEL of 0.52 mg/kg/day
 suggested in the 2-year chronic toxicity study in rats (McCormick et aL,  1988).

     Therefore, a NOAEL of 0.52 mg/kg/day observed in toe 2-year chronic study in rats is used for
 calculation of the RfD.
                                           vm-io

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Simazine Criteria Document
          Table Vin-2.  Summary of Candidate Studies for Derivation of the DWEL for Simazine
Specie*
Mouie




Mouse

R«

Rat



Rat


Dog




Dog

Exposure
Route duniioD
Diet 17 to 22
months




Diet 93 weeks

Diet 2 yean

Diet 74 days
(jea.1);
81 days
(lea. 2);
uadeier-
mined
Diet 2 yean


Diet 2 yean




Diet 1 year

Eadpointt
Food con-
sumption.
gross
pathology.
Oisto-
patbolojy
Body weigbi

Systaltic
toxieiiy
Three-
generation
reproduction
winy
Body weigbL
denuulogy

Thyroid
byperplasia



Body weigol.
hematology
NOAH. LOAEL
(mg/kg/day) ' (mg/kg/day) Refemce
— « ^ Ciba-Oeiw
(1980-b)




6 ISO Hizelene and
Green (1988)
>5 — Gysin and
Knuiii (i960)
<2J 12 Woodatd
(puoittl KesearcB
uxieicy} Careontion
(1965a)
Q-S2 S.3 MeCormidc
etit
(1988)
3J — Woodart
Reseaieb
ogTsb)
cued in
NAS. 1977)
0.76 3.6 MeComiek and
Green (1988)
 •4ot deiorained.
                                           vm-n

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ounazme
              d. L>ocumeni
   Using this study, the DWEL is derived as follows:
Step 1:  Determination of the Reference Dose (RfD)
= (0.52 mg/kg/day)  =
                                                       (rounded to 5 u/kg/day)
where:
     0.52 rag/kg/day = NOAEL, based on depression  in  body weight and several hematological
                     parameters in the 2-year chronic toxicity study at 5.3 mg/kg/day.

                100 = uncertainty factor of 100 was chosen in accordance with NAS/OST guidelines
                     for use with  a NOAEL from an  animal study of lifetime duration.
 Step 2: Determination of the Drinking Water Equivalent Level (DWEL)


           D      n  (0.005 mR/kg/day) (70 kg)  =                 ^     g
                            (2 L/day)

 where:

    0.005 mg/kg/day = RfD (after rounding).      '

              70 kg = assumed body weight of an adult

            2 L/day = assumed daily water consumption of an adult


    The proposed DWEL reflects the assumption that 100% exposure to simazine is from drinking water.
 Since this chemical is used on food crops, the potential dietary exposure should be assessed. When the
 percentage contribution in  the diet is determined,  the DWEL should be adjusted to accommodate this

 factor in the determination of the MCLG.                        *


 C QUANTIFICATION OF CARCINOGENIC EFFECTS FOR SIMAZINE


 1. Categorization of Carcinogenic Potential
     Based on the available data, there is evidence (McCormick et al., 1988) to show that simazine is
  carcinogenic in female Sprague-Dawley rats, inducing mammary tumors at dose levels of 100 ppm (5.3
                                           VEI-12

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Simazine Criteria Document
mg/kg/day) and 1,000 ppm (63.1 mg/kg/day). In male rats, the formation of liver tumors (hepatocellular
adenomas/carcinomas) was  observed at 1,000 ppm (45.8 mg/kg/day). Table  Vffi-3 summarizes the
studies considered for the calculation of the carcinogenic risk estimates for simazine. No evidence of
carcinogenicity was found in an 18-monrh study with mice (Innes et al., 1969)  or a 95-week mouse
oncogenicity study (Hazelette and Green, 1988).  The 2-year study with rats  by Hazleton Laboratories
(1960) was not considered adequate to assess the carcinogenicity of simazine  because of the high
incidence of respiratory and ear infections.  Similarly, the 17- to 22-month study in mice by Ciba-Geigy
(1980t)yas invalid.

    Applying the criteria described in EPA's guidelines for the assessment of carcinogenic risk (U.S.
EPA, 1986), simazine may  be classified in Group C: Possible Human Carcinogen.  This category is
use'd for substances with limited evidence of carcinogenesis in animals in the absence of human data.

2.  Quantitative Carcinogenic Risk Estimates

    Quantitative carcinogenic risk estimates of simazine have been developed (  Fisher , 1989). "The
Agency's peer review committee recommended (Fisher, 1989) the use of rat mammary gland carcinomas
for the estiamtion of Qt*. The females had a statistically significant incidence of mammary carcinomas
(40/78) and adenomas/carcinomas (61/78) at the high dose (1,000 ppm) and in carcinomas (20/75) at the
mid dose (100 ppm) as compared to controls (16/89 for carcinomas, 39/89 for adenomas/carcinomas).
There was also a significantly increasing trend in mortality in females with dose increments of simazine
from 100 to 1,000 ppm, as compared to controls (for details see Section V.B.2  and Section VS.,
Carcinogenicity). The calculation of the unit risk was made by the use of Weibull 83 (time to death
with tumor multistage mode by K. Crump). The unit risk calculated from the female data in ppm doses
was converted to rat mg/kg/day by the use of Lehman's tables and then to human equivalents by the use
of interspecies surface area adjustments as recommended by EPA cancer guidelines (U.S. EPA, 1986).

    The unit risk, Qt*. of simazine is 1.2 x 10'1 (mg/kg/day)'1 in human equivalents. The oncogenic risk
of exposure to drinking water is 3.4 x 10"* assuming that a 70-kg man consumes 2 liters of water per
day with a Maximum Contaminant Level Goal of 1 ppb (1 ug/L) for simazine. It is to be noted that
 Qt* is an estimate of the upper-bound (95%) on risk and that as stated in the EPA guidelines (U.S. EPA,
 1986), the true value of the risk is  unknown and the lower limit of the risk may be as low as zero.
                                           Vm-13

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Simazine Criteria Document
          Table Vffl-3. Summary of Candidate Studies Considered for Derivation of the
                         Carcinogenic Risk Estimates for Simazine
Species
Mouse
Mouse
Mouse
Rai
RM
Exposure Dote
Route duration (mg/Xg/day) Results
liionjich 18 months 215 Treatment did noi increase tumor
tube incidence.
Diet 17 to 22 1.5 to 300 Invtlid IBT study.
months
Diet 95 weeks 6 to 600 No evidence of oeopiastic
lesions.
Diet 2 yeas 0.05 to 5 Tumors in high-dose females:
btitopainological details.
not provided
Diet 2 yean 0.52 to 50 At doses of 100 and 1.000 ppro
(5.3 tod 63.1 mgAg/day).
incidence of micusary gland
catcinoma is female no. la mile
rats, hepaiocellultr idenomas/
caicinomaf wen observed at 1,000
ppra (45.8 mg/kg/dty).
Reference
innes et aL (1969)
Ciba-Geigy <1980b)
Htzeteae and Green
Green (1988)
(1960)
McCormick et al.
(1988)
                                         vm-H

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Simazine Criteria Document
D.  EXISTING GUIDELINES AND STANDARDS

    A tolerance level of 10 }ig/L has been established for simazine and its metabolites in potable water
when present as a result of application to growing aquatic weeds (U.S. FDA, 1979).

    Residue tolerances for simazine in or on raw agricultural commodities ranged between 20 and 15,000
mg/kg (U.S. EPA, 1986b).

E.  SUMMARY

    Table Vin-4 summarizes the HA and DWEL values (calculated on the basis of noncarcinogenic
endpoints).  Since no studies found in the literature were suitable for determination of the One-day and
Ten-day HA values for simazine, the Longer-term HA of 0.072 mg/L for a 10-kg child is used as a
conservative estimate for the One-day and Ten-day HA values.  A. DWEL of 0.175 mg/L (rounded to
180 ug/L) was calculated for a 70-kg adult.  Simazine is classified as a Category C carcinogen.  Excess
cancer risk has been determined for simazine.  The Qt* = 1.2 x 10*' (mg/kg/day)'1 in human equivalents.
The oncogenic risk of exposure to 1 ppb simazine in drinking water is 3.4 x 10"*, assuming that a 70-kg
man consumes 2 liters of water per day.
                                          VHI-15

-------
 Simazine Crusru; Document
           Table vni-4.  Summary of Quantificadon of Toxicological Effects for Simazine
       Value
Drinking Water
Concentration
(ug simazine/L)
Reference
 One-day HA for 10-kg child            —'

'^Ten-day HA for 10-kg child            —'

..Longer-term HA for 10-kg child       70

 Longer-term HA for 70-kg adult       300"

 DWEL  for 70-kg adult                180

 Excess cancer risk (3.4 x 10"6)          le
                        McCormick and Green (1988)

                        McCormick and Green (1988)

                        McCormick and Green (1988)

                        McCormick and Green (1988)

                        McCormick et al. (1988)
 The Longer-term HA value for a 10-kg child is recommended as a conservative estimate of the One-day
  and Ten-day HA values.
 •"It is advisable that the Longer-term HA value of 70 ug/L for a 10-kg child also be used as the Longer-
  term HA value for a 70-kg adult, because the relative source contribution for Longer-term dietary
  exposure for adults could not be determined at this time from the available data.
 The unit drinking water risk is the risk associated with exposure to 1 ug/L simazine; this is 3.4 x 10*
  excess cancer risk per year.
                                             VHI-16

-------
   Simazine Criteria Document
                                       IX.  REFERENCES
   Anderson DG. Copley M. 1988. U.S. EFA Data Evaluation Report on Simazine Technical: A 52-week
   Oral Feeding Study in Dogs by McCormick GC and Green JD. Ciba-Geigy Corp.'  Study No. A7/17
..  (MIN 862001). Report No. 87122.  MRJD No. 406144-02.               •>      '.
       *                                                    * *      .
 *                                         •                           .
  • Anderson KJ, Leighty EG,  Takahashi MT.  1972.  Evaluation of herbicides  for possible  mutagenic  .,
•   properties. J. Agric. Food Chem. 20:649-656. '       ,

   Bakke JE, Robbins JD. 1968. Metabolism of-atrazine and simazine by the goat and sheep. Abstr. Pap.
   155th National Meeting Am. Chem. Soc. (A43).

   Bohme C, Bar F.   1967.  The transformation of triazine herbicides in the animal organism.  Food v
   Cosmet Toxicol. 5:23-28.

   Bradway DE, Moseman RF. 1982. Determination of urinary residue levels of the N-dealkyl metabolites
   of triazine herbicides. J. Agric. Food Chem.  30:244-247.
                                                                                           i
   Bumside OC, Schmidt EL, Behrens R. 1961. Dissipation of simazine from the soil. Weeds 9:477-484.
                                                                                           i
   •Chen BQ. 1981.  Experimental studies on toxicity and teratogenicity of simazine. Chung Hua Fang I
   Hsueh Tsa Chih.  15(2): 83-85.

   Ciba-Geigy Corporation.  1976. Product label-Aquazine. Agricultural  Division, Greensboro, NC.

   Ciba-Geigy Corporation.  1980a. 21-Day Dermal Study in Rabbits. Bio-Research. No. 12017. January
   14.

   Ciba-Geigy Corporation.  1980b.  Carcinogenicity Study With Simazine Technical in Albino Mice.
   MRID  No.  154317.   Accession Nos. 255580, 255581.  IBT Report
   No. 8580-8907.

   Ciba-Geigy Corporation.  1984.  A Teratology Study  of Simazine Technical in New Zealand White
   Rabbits.  MRID No. 161407.  Accession No. 252938.

   Ciba-Geigy  Corporation.   1991.   Two-Generation Reproductive Toxicology Study  in  Rats, EPA
   Guidelines No. 83-4. MRID No. 418036-01.  RA Accession No. 96 BB.

   Clayton GD, Clayton FE.  1981.  Patty Industrial Hygiene and Toxicology.  Vol.  1, 2A,  3.  3rd Ed.
   New York:  John Wiley and Sons, p. 2775.

   Commoner B.  1976. Reliability of bacterial mutagenesis techniques to distinguish carcinogenic and
   noncarcinogenic chemicals.  Availalbe from:  NTIS, Springfield, VA.

   Cosmopolitan  Safety Evaluation, Inc.  1985.  Acute Oral Toxicity Study in Rats. MRID No. 148897.

   Dalgaard-Mikkelsen SV, Poulsen E.  1962.  Toxicology of herbicides.  Pharmacol. Rev. 14:225-250.
                                              IX-1

-------
 Simazine Criteria Document
 DeUarco VL, Movoumin KH, Waters MD.  1986.  Aneuploidy data review committee: Summary
 compilation of chemical data base, and evaluation of test methodology. Mutat.  Res. 167:149-169.

 Didier R. 1974.  Action du 2,4,5-T et de la simazine sur les gonades de 1'embiyon de poulet et de caille
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                                                                *

 Dollenrneier P.   1988.  Structural chromosomal aberration test-Chromosome studies on  human
 lymphocytes in vitro. "Ciba Geigy report No. 871099.  MRID No. 406144-07.

:Dsriurov A. 1979.  Histological changes in organs of sheep in chronic simazine poisoning. .Zentralbi
^Veterinaermed.  Reihe'A. 26:44-54.
            .            »

:.DunaChie JF, Fletcher WW.  1970. The toxicity of certain herbicides to hens' eggs assessed by the egg-
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           .'   .         .   %             • •                                '          •   •
 Eisenbeis SJ,.Lynch DL, Hampel AE.  1981. The Ames mutagen assay'tested against herbicides and
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 Esser HO, Dupuis G, Ebert E, Vogel C, Marco GJ.  1969.  S-triazines. In: Kearney PC, Kaufman DD.
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                              .»       .            '                                      '
 Fahrig R.  1974.  Comparative mutagenicity studies  with pesticides.  IARC Sci. Publ. 10:161-181.
          •"' •"••**-      • ;
 Fisher 8. 1989. Simazine-Quantitative Risk Assessment, Two Year Chronic/ Oncogenicity Sprague-
 Dawley Rat Study.  Washington, DC: U.S.  Environmental Protection Agency.

 Freed VH.  1976.  Solubility, hydrolysis, dissociation constants and other constants. In: A Literature
 Survey of Benchmark Pesticides.  Washington, DC: George Washington University Medical Center, p.
 14.

 Ghassemi M, Fargo L, Painter P, Quinlivan S, Scofield R. Takata A. TRW Environmental Division.
 1981. Environmental Fates and Impacts of Major Forest Use Pesticides.  Redondo Beach, CA:  U.S.
 Environmental Protection Agency, Office of Pesticides and Toxic Substances. Contract No. 68-02-3174.

 Ghiazza G, Zavarise G, Lanero M. Ferraro G.  1984. Sister chromatid exchanges induced  in human
 lymphocyte chromosomes by thfluralin, atrazine, and simazine. Boll. Soc. Ital. Sper.  60( 11 ):2149-53.

 Guddewar MB, Dauterman WC.  1979.  Studies on a glutathione S-transferase  preparation from mouse
 liver which conjugates chloro-s-triazine  herbicides. Pestic. Biochem. Physiol. 12:1-9.

 Gysin H, Knusli E.  1960. Chemistry and herbicidal properties of triazine derivatives.  In:  MetcalfRL,
 ed. Advances in Pest Control Research.  Vol.ni. New York:  Interscience Publishers Inc., pp. 328-330.

 Hance RJ, Smith PD, Byast TH, Cotterell EG.  1976.  Variability in the Persistence and Movement in
 the Field of Abnormally High Rates of Simazine and Linuron:  Some Wider Implications. Proc. 1976
 Brit. Crop Rot. Conf.-Weeds, pp. 643-648.
                                            IX-2

-------
Simazine Criteria Document
Hapke  H,   1968.-  Research into The toxicology  of weedkiller simazine.  Berl. Muench. Tieraerztl.
Wochenschr. 81:301-303.
                                                                                         •>

Haque R, Freed VH.  1974.  Behavior of pesticides in the environment: Environmental chemodynamics. '
Residue Rev. 52:89-116.                  '              .            ./  .
                                                                              o
Hams CI, Warren GF.  1964.' Adsorption and desorption of herbicides by soil. Weeds  12:120-126- .

Hazelette JR. Green JD.  1988.  Simazine Technical.  95-Week Oral Toxicity/Oncogenicity Study In
Mice.  Ciba-Geigy Corp.  Laboratory Study No. 842121. MRID.No. 406144-04.     •           '
                                                  *        *                «•
Hazleton Laboratories.  1960.  Two-year dietary feeding study in albino rats. MRJD Nos.  37752,25441,
25442, 42793, 80626.  Accession Nos. 222507, 100942,    '
42793,090488.              ;                             .                    .   9

Helling'CS.  1970.  Movement of s-triazine herbicides in soils. Residue Rev.  32:175-210-.  -    0
     -•'••'      *
Innes JRM, Ulland BM, Valerio MG.  1969.  Bioassay  of pesticides and industrial  chemicals  for
tumorigenicuy in mice.  A preliminary note. J. Natl. Cancer Jjist. 42:1101-1114.

loannou YM, Copley M.  1988.  U.S. EPA Data Evaluation Report on SimazineTechnical: 104-Week,
Oral Chronic Toxicity and  Carcinogenicity  Study°in Rats by McCormick CC, Arthur AT, Green JD,
Ciba-Geigy Corp. Study No. 2-011-09. MRID No. 406144-05.

Khan SU, Marriage PB.  1979.  Residues of simazine  and hydroxysimazine in an orchard soil.  Weed
Sci. 27:238-241.

Kozlowski TT, Kuntz JE  1962.  Leaching and movement of simazine and propazine in forest nursery
soil. Weed Abstr. 11:1994.

Leblova S, Galociova J, Cerovska N.  1983. A comparative study of the effect of triazine herbicides
on alcohol dehydrogenases  isolated from various  sources. Environ. Res. 30:389-392.

Lehman AJ. 1959. Appraisal of the safety of chemicals in foods, drugs and cosmetics.  Assoc. Food
Drug Off., U.S. Q. Bull.

Lewis  RJ, Tatken RL, eds.  1980. Registry of Toxic Effects of Chemical Substances.  1979 Ed. VoL
2. Cincinnati, OH: U.S. Dept.  of Health and
Human Services, p. 637.

Mainiero J, Wimbert K, Wright J, Infuma RN, Arthur AT, Yau ET.   1986.   Simazine Technical.  A
Teratology Study in Rats.  Ciba-Geigy Corp.  Report  No. 83058. MRID No. 406144-03.

McCormick GC, Arthur AT,  Green JD. 1988.  SimazineTechnical:   104- Week Oral
Chronic Toxicity and Carcinogeniciiy Study in Rats.  Ciba-Geigy Corp. Study No. 2-011-09.  MRJD
No. 406144-05.

McCormick GC, Green JD.  1988.  Simazine Technical:  A 52-Week Oral  Feeding  Study in Dogs.
Ciba-Geigy Corp. Study No.  A7/17 (MIN 862001). MRID No. 406144-02.


                                           IX-3

-------
Simazine Criteria Document
 Marriage PB. Saidak WJ, Von Stryk FG.  1975. Residues of-atrazine.-simazme,, linuron and diuron after
 repeated annual applications in a peach .orchard. Weed Res. 15:373-379.
                                                             t   ^ i
                              <"
 Manin H, Worthing CR, eds.  1977.  Pesticide Manual.  Worcester, England: British Crop Protection ^
 Council.

 Mazaev VT.  1965.   Experimental determinations of the maximum  permissible Concentrations of
 cyanuric acid, simazine, and a 2-hydroxy derivative of simazine in water reservoirs.  Chem. Abstr.
 62:15304.                   '   •'   •                                               •

 MeisterRT.  1984. Farm Chemicals Handbook. Willoughby, OH:  Meister Publishing Co., p. C214.
                    » '               *                 •
•Messner B.  1979.  Increases in rat liver cyclic AMP and glycogen phosphorylase caused by the
 herbicide, ariazine. Biochem. Pharmacol. 28:207°-210.
           .  •
 Mountfort RF, Robinson GW, Ritter DL  1986.  EPA Reg. No.' 100-541,  Simazine Technical:  Ciba-
 Geigy Response to EPA Comments on Rabbit Teratology Study, Ace. Nos. 252938, 260651.  Caswell
 No. 740.
                                                           »                             *

 Murnik MR, Nash CL.  1977. Mutagenicity of the triazine herbicides atrazine. cyanazine, and simazine,
 in Drosophila melanogasrer.  J. Toxicol. Environ. Health 3:691-697.
                                                                                          <
 MyhrBC  1973. A screen for pesticide toxicity to protein and RNA synthesis in HeLa cells. J.'Agric.
 Food Chem. 21:362-367.
                                                               *
 NAS.  1977. National Academy of Sciences. Safe Drinking Water Committee. Drinking Water and
 Health,  vol. J. Washing tony7' DC: 'National AcaHom^ Pr'e'ss. -p>-  i<>-637~
NAS.  1980. National Academy of Sciences.  Drinking Water and Health, VoL 3. Washington, DC:
National Academy Press,  pp-  25-67.

Nishimura H, Nishimura H, Oshima H.  1982.  Survey on the mutagenicity of two pesticides by the
Salmonella microsome test.  Aich Ika Daigaku Igakukai Zasshi. VoL 10, ISS 4:305-12.

Oledzka-Slotwinska H.  1974.  Effects de la simazine sur rultiastructure des hepatocytes et 1'activite
des cenaines hydrolases.  Pest. Abstr. 8:75-3032.

Orr GR.  1985. Review of Simazine Metabousm in Rat.  MRID No. 262646.

Orr GR, Simoneaux BJ.  1986. Disposition of Simazine in Rat  MRID No. 262646.

Palmer J3, Radeleff RD.  1964. The toxicologic effects of certain fungicides and herbicides on sheep
and canfe. Ann. N.Y. Acad. Sci 111:729-736.

Palmer JS, Radeleff RD.  1969. The toxicity of some organic herbicides to cattle, sheep, and chickens.
Production Research Report No. 106, U.S. Department of Agriculture, Agricultural Research Service.
 1-26.
                                            IX-4

-------
Simazine Criteria Document
Plewa  MJ, Wagner ED, Gentile  JM.  1979.  Analysis of the  mutagenic properties of pesticides
incorporating animal and plant activation.  Environ. Mutagen. 1:142.

Pliss GB, Zabezhinsky MA. 1977.  Carcinogenicity of symmetric triazine derivatives. Pest. Abstr. 5:72-
1017.

Robinson GW, Mountfort R, Jaeger RB.  1985. ID No. 100-541.  Simazine Registration Standard:
Recent Toxicity Studies, Ace. Nos.  257692,257694, and 244268. Caswell No. 740.  U.S. Environmental
Protection Agency, Office of Pesticides and Toxic Substances.

Simmons  VF,  Poole DC,  Riccio ES, Robinson DE,  Mitchell AD, Waters MD.   1979. In vitro
mutagenicity and genotoxicity assays of 38 pesticides. Environ. Mutagen. 1:142-143.

Simoneaux BJ. Sy A. 1971. Metabolism of Simazine and Its Metabolites in Female Rats. MRID No.
262646.

Sittig M.  1980.  Simazine.  In: Pesticide Manufacturing and Toxic  Materials Control Encyclopedia.
Park Ridge, NJ:  Noyes Data Corp.,  p. 673.

Spencer HW, Copley MP.  1989.  U.S. EPA Data Evaluation Report on Simazine: Three-Generation
Reproduction Study in the Rat by Johnston CD. Woodard Research Corporation.  Study sponsored by
Ciba-Geigy Research Laboratories.  MRID Nos. 0023365, 00080631.

St.  John LE, Ammering JW, Wagner DG,  Warner RG, Lisk DJ.   1965.  Fate of 4,6-dinitro-2-
isobutylphenol, 2-chloro-4,6-bis-(ethylamino)-s-triazine, and pentachloronitrobenzene in the dairy cow.
J. Dairy Sci. 48:502-503.

Tai CN, Breckenridge C, Green JD.  1985a.  Simazine Technical  Subacute Oral 13-Week Toxicity
Study in Rats.  MRID No.  143265.  Accession  No. 257693.

Tai CN, Breckenridge C, Green JD.  1985b.  Simazine Technical.  Subacute Oral 13-Week Toxicity
Study in Dogs. MRID  No. 146655.  Accession No. 257693.

Talbert RE. 1963. Studies of the behavior of some triazine herbicides in soils.  Diss. Abstr. 24:923.

USDA.   1984.  United States Department  of Agriculture.  Forest Service.  Pesticide  Background
Statements. Vol. 1. Herbicides.

U.S. EPA.  1985.  U.S. Environmental Protection Agency.  U.S. EPA Data Evaluation Report 01
Simazine  SOW:  Two-Year Dietary  Feeding  Study in Dogs.  Study conducted by Woodard Research
Corporation for Ciba-Geigy Corporation.  MRID Nos. 00023364, 00080627.

U.S. EPA.  1986.  U.S. Environmental Protection Agency. Guidelines for carcinogen risk assessment.
Fed. Reg. 51(185)33992-34003. September 24.
                                            IX-5

-------
Simazine Criteria Document
U.S. FDA.  1979.  U.S. Food and Drug  Administration.  Code of Federal Regulations.  21 CFR
193.400.  April 1.

Valencia  R.   1981.   Mutagenesis  screening of pesticides  using  Drosophila. Project  Summary.
Research Triangle  Park, NC:   U.S. Environmental  Protection Agency, Health  Effects  Research
Laboratory.  EPA-600/S1-81-017.

Walker EM Jr., Gale GR,  Atkins LM, Gadsden RH.  1979.  Some effects of atrazine on Ehrlich
ascites tumor cells in vitro and in vivo.  Bull. Environ. Contain. Toxicol. 22:95-102.

Waters MD, Saindhu  S, Simmon ZS.   1982.   Study of pesticide genotoxicity.   In: Fleck RA,
Nollaender A, eds.  Gen. Toxicol. Agric. Persp.  21:275-326.  Basic Life Sciences Series.

Weed Science  Society of America.  1983.  Herbicide Handbook.  5th Ed. Champaign, IL:   Weed
Science Society of America, pp. 433-437.

Windholz M, ed.  1983.  The Merck Index:  An Encyclopedia of Chemicals, Drugs, and Biologicals.
10th Ed.  Rahway, NJ:  Merck and Co.. p. 1225.

Woodard Research  Corporation.   1965a. Three-generation reproduction study of simazine in the diet
of rats. MRID Nos. 23365, 80631.

Woodard Research Corporation.  1965b.  Two-year dietary study in dogs.  MRID Nos. 00023364,
00080627.

Worthing CR.   1979.   The Pesticide Manual:  A World Compendium. 6th Ed. Croydon:  British
Crop Protection Council, p. 474.

Yelizarov GP.   1977.   Occupational skin diseases caused by simazine and propazine. Pest.  Abstr.
6:73-0352.

Zimdahl  RL, Freed VH, Montgomery ML, Furtick WR.  1970,  The degradation of ttiazine and
uracil herbicides  in soil.  Weed Res.  10:18-26.
                                            IX-6

-------
   APPENDIX
HUMAN EXPOSURE

-------
 Human Exposure to Simazine
                                   CONTENTS
 HUMAN. EXPOSURE	
    A.  EXPOSURE ESTIMATION
    ..  1. Drinking Water	
       2. Diet.::...;	
_1    ' 3. Air ...'	
    B.  SUMMARY	
~ '  C  REFERENCES	
A-l
A-2'
A-2
A-2
A-4
A-4
A-8
                              '   LIST OF TABLES

 Table A-l. Estimated Daily Intake of Sinffiine From Drinking Water
'Table A-2. Tolerances for Simazine .'	'.	
A-3
A-5

-------
          H.-oosure to Simazine
                                      HUMAN EXPOSURE

      Humans may be exposed to chemicals such as simazine from a variety of sources, including
  surface water, groundwater, drinking water, food, ambient air, and consumer products.
                                                                      o
      Simazine has. been found in 877 of 5,067 surface water samples analyzed and in 229 of 2,282
  groundwater samples.  Samples were collected at 472 surface water locations and 1,730 groundwater'
  locations, and simazine was found in 22 States.*  The- 85th perceiitile of all non-zero samples was
  2.18 ug/L in surface water and 1.60 ug/L in groundwater sources. The maximum concentrations
  found in ground and surface water were 800 ug/L and 1,300 ug/L, respecfively,  Simazine has been
  found .in groundwater  in California, Pennsylvania, and Maryland; typical positives were 0.2 to 3.0
                                          •
  ppb (Cqhen et al., 1986). EPA documented findings of simazine in groundwater in several States,
                           0                q.      •       o   -
  including California, .Connecticut, Maryland, "Nebraska, and Pennsylvania (U.S. EPA, 1989). 'Several
  detections have approached or exceeded the Maximum Contaminant Level goal of 1 ppb.  Additional
                                        o               '                                       «
                                                                    "                   .      *•
' ' available data provided by the registrant indicated that simazine is present at the level of 0.25 ppb of
                                                                                              t
  above in groundwater in 6 of 11 states studied across the country.  However, nationwide assessment
  is not possible from these data in view of the limited scope of the study  and the low intensity of
  sampling.  There is evidence for the detection of simazine in surface waters, and maximum
  detections are found in Pennsylvania, Ohio, Michigan, Wisconsin, Texas, and Nebraska. The
  validity of. these data has not been confirmed.

      The following analysis of human exposure to simazine is limited to drinking water, food, and
  ambient air because those media are considered to be sources common to all individuals.  Even in
  limiting the analysis to these three sources, it must be recognized that  individual exposure will vary
  widely based on many personal choices and on several factors over which little  control exists. Daily
  exposure  and intafee are profoundly affected by the area in which an individual lives, works, and
  travels;.by an individual's diet; and by physiologic characteristics related to age, sex, and  health
  status. Individuals living in the same neighborhood  or even yi the same household can experience
  vastly different exposure patterns.

      Human exposure to simazine, through close contact with the herbicide, has been documented in
   124 workers from the U.S.S.R. (Yelizarov, 1977). The workers suffered from acute and subacute
  dermatitis (for details, see Section VLA). Detailed information concerning the occurrence of and

                                                A-l

-------
 Human Exposure to Simazine
 exposure to simazine in the environment is presented in a report by Borum (1984). Section A of this
 appendix summarizes the pertinent information presented in that document to assess the relative
                   ™                                      »
 source contribution from drinking "water, food, and air.  Available information is presented on the
                           •,                •                     e
 range of human exposure to and intake of simazine from drinking water, food, and ambient  air for a
 70-kg aciuir male;  It is not possible, to provide an estimate of the number of individuals experiencing
 specific combined  exposures from these three sources.                                 „  '

 A. EXPOSURE ESTIMATION          '            .  .     •       -         '  •  -  '       :
    1. Prinking Water           .                                               ?
•*•-            "                      *                                                    •

    Levels of simazine in drinking water vary from one location to another.  The highest
 concentration of simazine reported in the National Screening Program (NSP) for Organics in
 Drinking Water was 4.4 pg/L (Borum, 1984).  However, concentrations of simazine in drinking
                                                                                           i
 water typically appear to be somewhat lower than this level. Analysis of the data in the NSP
 suggests that median levels of simazine in drinking water systems are below 0.1 pg/L, since only 1
 of the 12 groundwater systems and 13 of the 104 surface water systems sampled contained levels of
 simazine above the quantification limit of 0.1 ug/L (Boland, 1981). Some areas may not contain
 simazine in drinking water. Sufficient monitoring data are not available to determine regional
 variations in levels of exposure to simazine.

    The estimated daily intake of simazine from drinking water of a 70-kg adult m?.le consuming 2
 L/day ranges from 0.0 to 0.126 pg/kg/day (Table A-l). However, the values presented do not account
 for variances in individual exposure or uncertainties in the assumptions used to estimate exposure   >
                                                                                           i
 levels.

    A tolerance level of 10 pg/L has been established for simazine and its metabolites in potable
 water when present as the result of application to growing aquatic weeds (U.S. EPA, 1986).
    2.  Diet
     Data obtained on levels of simazine in foods in the United States were insufficient for use in
 determining typical dietary intake levels.  Tolerances for residues of simazine and combined residues
                                                                             3
                                             A-2

-------
Human exposure to Simazine
4   "           Table A-l.  Estimated Daily Intake of Simazine From Drinking Water*





   Drinking water concentration (pg/L)          *         Intake (pg/kg/day)



    °     »                                                    '

              o.o      -...             .        o.o
                                                                            1


           -   0.1                                             0.003



              4.4               "            .                 0.126
                                         0




'Assumed consumption of a 70-kg adult male is 2 L water/day.
                                             A-3

-------
Human Exposure to Simazine
of simazine and its metabolites, in and on raw agricultural commodities, and in foods are listed in
Table A-2. These data cannot be used, however, to estimate typical dietary intake.
    3.  Air
    No data were qbtained on levels of simazine in ambient air.  Therefore, the intake of simazine
from ambient air could not be estimated.          .                   .    .
                         n
      *            6

B.  SUMMARY            '
                  '                     e»
    Sufficient dataware available to indicate that simazine can  leach into groundwater although a
nationwide assessment is not possible at this time because of  the limited scope of the study and the
low intensity of sampling. Simazine has been found in surface water samples, but the validity of
these findings remains to be confirmed.  Data are being developed on the maximum concentrations
of simazine in these waters as well as on the major source contributor to total intake of simazine.
                                              A-4

-------
Human Exposure to Simazine
                            Table A-2. Tolerances for Simazine
       Commodity
     Food

        Sugarc'ane syiup

        Sugarcane molasses
                        o
     Raw agricultural commodity
Tolerance (mg/kg)
          • 1,000
           «
           1,000
Alfalfa
forage
hay
Almonds
hulls-
' • Apples
Artichokes
Asparagus
Avocados
Bananas
Bermuda grass
forage
hay
Blackberries
Blueberries
Boysenbenies
Cattle
fat
meat by-products
meat
15,000
15,000-
15,000
250
250 i
250
500
10,000
250
200*
15,000
15,000
15,000
250
250
250
20
20
20
                                                                             (continued)
                                          A-5

-------
Human Exposure to Simazine
v •
. o Commodity •. ••'
A '
. - : -Cherries
- Com
• • ; fodder • 	 ' '
•forage
fresh (including sweet)"
grain
Cranberries
Currants
• ° » 3
Dewberries
Eggs t
Filberts-
Fish
Goats
fat
meat by-products
meat
Grapefruit
Grapes
Grass
forage
hay
Hogs
fat
meat by-products
Horses
fat
meat by-products
meat
Table A-2. (contiqued)
Tolerance (mg/kg)
250
0
.3 *
250
250 ...
.250 ....
250-
250 ' ,
. . 250 - - '
250
20
•i,
250 \
12,000*
20
20
20
250
250
15,000
15,000
15,000
20
20
20
20
20
                                                                             (continued)
i
                                          A-6

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Human Exposure to Simazine
p '
Commodity
Lemons . • '
Loganberries
Macadarnia nuts
Milk
Olives
Oranges 0
Peaches
t
Pears
Pecans

Plums .
Poultry
fat
meat by-products
meat
Raspberries
Sheep
fat
meat by-products
meat
Strawberries
Sugarcane
Table A-2. (continued) • .
Tolerance (mg/kg)
250
.250 .
.250 • .-.-••
20
. ' . , 250
250
. 250 .
250 - ' - i
'"•"'• ' 100
a
250
20
20
20
250
20
20
20
250
250
Tor combined residues of simazine and its metabolites.
''Kernels plus cob with husk removed.

SOURCE: Adapted from U.S. EPA (1986).
                                         A-7

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                            >
  Human Exposure to Simazine




  C.  REFERENCES                                   .         '-             •

                        o            i             .                      .

  Borurn D.  JRB Associates.  1984. Pesticide Occurrence in Drinking Wate/, Food and Air.  Vol. n.

  Draft prepared by JRB Associates, McLean, VA, for Office  of Drinking Water, U.S. Environmental
'  Protection-Agency, Washington, DC. EPA Contract No. 68-01-6388.

              '       .          *  '                                                   •'
  Boland PA.  SRI International.  1981.  National screening program for organics in drinking water.

  Pan n. • Data.  Prepared by SRI International, $lenlo park, CA, for Office of Drinking Water, U.S.

 Environmental Protection Agenqy, Washington, DC. EPA Contract No. 68-01-4666.

  .'*-.'»•''*      '    . ••         '                           '   '
 Cohen SZ, Eiden C, Lorber MN.  1986. Monitoring ground water for pesticides in the U.S.A. In:-

 American Chemical Society Symposium Series titled Evaluation'of Pesticides in Ground Water (in
 press).'



 U.S. EPA.   1986. U.S. Environmental Protection Agency. Code of Federal Regulations,  40 CFR
 180.213." July 1.             '


                                        9                  »
U.S. EPA.   1989. Guidance for the Registration of Pesticide Products Containing Simazine as the
Active Ingredient. Internal/External Review Draft. August 1989.

                                                rt

YeJizarov GP.  1977. Occupational skin diseases caused by simazine and propazine.  Pest, Abstr.  ,
6:73-0352.
                                          A-8

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