TXR# 0050775 TXR# 0050775 May 30, 2002 May 30, 2002 OFFICE OF PREVENTION, PESTICIDES AND MEMORANDUM: TOXIC SUBSTANCES Subject: 107201: The Toxicology Chapter for the TRED for Hexazinone.

DP Barcode: D275620 Submission: S598837 ReReg Case# 0266 CAS#: 51235 04 02 From: David G Anderson RRB 2 HED (7509C)

To: Carol Christensen, Risk Assessor RRB 2 HED (7509C)

Thru: Alan Nielsen, BSS RRB 2, HED (7509C)

cc Pauline Wagner The Toxicology Chapter for the Tolerance Reassessment Evaluation Decision (TRED) for Hexazinone is attached. 1 Hexazinone PC Code: 107201 Toxicology Disciplinary Chapter for the Tolerance Reassessment Evaluation Decision Document Date completed: May 16, 2002 Prepared for: Health Effects Division Office of Pesticide Programs U. S. Environmental Protection Agency Arlington, VA 22202 Prepared by:

David G Anderson form: FINAL June 21, 2000 2 TABLE OF CONTENTS 1.0 HAZARD CHARACTERIZATION ........................................ 3

2.0 REQUIREMENTS ..................................................... 4

3.0 DATA GAP( S) ........................................................ 5

4.0 HAZARD ASSESSMENT ............................................... 5 4.1 Acute Toxicity ................................................... 5 4.2 Subchronic Toxicity ............................................... 5 4.3 Prenatal Developmental Toxicity ...................................... 8 4.4 Reproductive Toxicity ............................................ 11 4.5 Chronic Toxicity ................................................. 13 4.6 Carcinogenicity ................................................. 14 4.7 Mutagenicity ................................................... 18 4.8 Neurotoxicity ................................................... 21 4.9 Metabolism .................................................... 22 4.10 Special/ Other Studies ............................................. 23

5.0 TOXICITY ENDPOINT SELECTION .................................... 23 5.1 See Section 9.2 for Endpoint Selection Table. ........................... 23 5.2 Dermal Absorption ............................................... 23 5.3 Classification of Carcinogenic Potential ................................ 23

6.0 FQPA CONSIDERATIONS ............................................ 24 6.1 Special Sensitivity to Infants and Children .............................. 24 6.2 Recommendation for a Developmental Neurotoxicity Study ................. 24

7.0 OTHER ISSUES ...................................................... 24

8.0 REFERENCES ....................................................... 24 Other references ...................................................... 27

9.0 APPENDICES ..................................................... 28 9.1 Toxicity Profile Summary Tables ..................................... 29 9.1.1 Acute Toxicity Table ....................................... 29 9.1.2 Subchronic, Chronic and Other Toxicity Tables ................... 29 9.2 Summary of Toxicological Dose and Endpoints .......................... 34 HEXAZINONE/ 107201/ May/ 2002 TRED Toxicology Chapter 3 1.0 HAZARD CHARACTERIZATION Hexazinone is a herbicide used to control a broad spectrum of weeds including woody plants in alfalfa, rangeland, pastures, woodlands, pineapple, sugarcane and blue berries. Non crop areas include ornamental plants and forests. Hexazinone is used as a pre emergent, post emergence herbicide. It is applied by direct spray to plants and to soils. There are no non occupational (residential) uses. Hexazinone is a triazine herbicide, which structurally dissimilar and toxicology different from other triazines, such as atrazine. The selectivity of triazine herbicides depends on the plant's ability to degrade or metabolize the parent compound. Sensitive plants have limited ability to metabolize hexazinone. Hexazinone acts through inhibition of photosynthesis. Hexazinone has low acute toxicity by the oral (Category III), dermal (Category IV ) and inhalation routes (Category III). Primary eye irritation is severe, causing corneal opacity and moderate irritation in unwashed eyes (Category I). It causes mild skin irritation and is classified Category IV for skin irritation. It is not a skin sensitizer in the Guinea pig. The 21 day dermal study in the rabbit showed no systemic toxicity and mild dermal irritation at the limit dose. Body weight decrement and liver toxicity were the most frequent effects shown in studies with hexazinone. Liver toxicity was seen in the chronic dog and mouse studies. Body weight decrement was seen in the chronic rat studies and the studies on reproduction. No quantitative or qualitative susceptibility was shown in the prenatal or reproduction studies. In a reproduction study, pup weight decrement occurred at the same dose as parental body weight decrement. No reproductive effects were seen in the study other than pup weight decrement. The rat prenatal study showed fetal weight decrement and possibly renal malformations but no increased susceptibility. The rabbit study possibly showed skeletal anomalies and delayed ossifications at the highest dose tested, however it is classified as unacceptable and susceptibility in this species could not be assessed. The chronic study in dogs showed severe body weight decrement, changes in liver related clinical chemistry values, and microscopic lesions. Body weight decrement was seen in a chronic carcinogenicity studies in rats and mice. Liver toxicity was seen in mice. The mouse carcinogenicity study showed an increased trend for liver carcinomas, but no pair wise significant increases. The rat study showed no carcinogenic potential. Based on these studies in rats and mice, hexazinone was classified in a group D, not classifiable as a carcinogen. Hexazinone is clastogenic in one in vitro test for chromosomal aberrations, but negative in the remaining six other mutagenicity studies including an in vivo micronucleus test in mouse bone marrow. Rat metabolism studies showed that hexazinone was rapidly absorbed and excreted and essentially no difference in the metabolism of males and females at high or low dose levels. Almost no parent hexazinone was recovered in urine or feces. Two major metabolites were recovered from feces and urine, in addition to lesser amounts of a third metabolite and individually small amounts of conjugated products from urine. The HIARC requested a 28 day inhalation study with hexazinone because of the concern for potential inhalation exposure based on the use pattern. The rabbit developmental toxicity study is classified as unacceptable. A 10X uncertainty factor was applied until this data gap is fulfilled. Another study in the rabbit, requested by Cal EPA, is expected to be submitted to OPP as well. HEXAZINONE/ 107201/ May/ 2002 TRED Toxicology Chapter 4 2.0 REQUIREMENTS The requirements (40 CFR 158.340) for food and non food use for HEXAZINONE are in Table 1. Use of the new guideline numbers does not imply that the new (1998) guideline protocols were used.

Table 1.

Test Technical Required Satisfied 870.1100 Acute Oral Toxicity .............................. 870.1200 Acute Dermal Toxicity ............................ 870.1300 Acute Inhalation Toxicity ......................... 870.2400 Primary Eye Irritation ............................. 870.2500 Primary Dermal Irritation .......................... 870.2600 Dermal Sensitization .............................. Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes 870.3100 Oral Subchronic (rodent) .......................... 870.3150 Oral Subchronic (nonrodent) ...................... 870.3200 21 Day Dermal ................................... 870.3250 90 Day Dermal ................................... 870.3465 90 Day Inhalation ................................ Yes Yes Yes No 1 No 2 Yes Yes Yes Yes No 870.3700a Developmental Toxicity (rodent) ................... 870.3700b Developmental Toxicity (nonrodent) ............... 870.3800 Reproduction ................................... Yes Yes Yes Yes No 3 Yes 870.4100a Chronic Toxicity (rodent) ......................... 870.4100b Chronic Toxicity (nonrodent) ...................... 870.4200a Oncogenicity (rat) ............................... 870.4200b Oncogenicity (mouse) ............................ 870.4300 Chronic/ Oncogenicity ........................... Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes 870.5100 Mutagenicity— Gene Mutation  bacterial ........... 870.5300 Mutagenicity— Gene Mutation  mammalian ......... 870.5xxx Mutagenicity— Structural Chromosomal Aberrations . 870.5xxx Mutagenicity— Other Genotoxic Effects ............ Yes Yes Yes Yes No Yes Yes Yes 870.6100a Acute Delayed Neurotox. (hen) .................... 870.6100b 90 Day Neurotoxicity (hen) ........................ 870.6200a Acute Neurotox. Screening Battery (rat) ............ 870.6200b 90 Day Neuro. Screening Battery (rat) .............. 870.6300 Develop. Neuro .................................. No 4 No 4 No 5 No 5 No 5

870.7485 General Metabolism .............................. 870.7600 Dermal Penetration .............................. Yes No 6 Yes No Special Studies for Ocular Effects 7 Acute Oral (rat) .................................. Subchronic Oral (rat) ............................. Six month Oral (dog) .............................

1 Study not required by use pattern. 2 A 28 day inhalation study was recommended by the HIARC and is required. 3 Data gap, another rabbit developmental toxicity is required 4 Required of organophosphates only. 5 Not required by toxicity pattern. 6 Study is optional. 7 Not required for this class of pesticides.

3.0 DATA GAP( S) HEXAZINONE/ 107201/ May/ 2002 TRED Toxicology Chapter 5 1. 28 Day Inhalation Study (Contact Agency before conducting test) 2. A Rabbit Developmental Toxicity Study is required (Guideline# 870.3700b)

4.0 HAZARD ASSESSMENT 4.1 Acute Toxicity Adequacy of data base for acute toxicity: The data base for acute toxicity is considered complete. No additional studies are required at this time. The acute toxicity data on HEXAZINONE technical is summarized below.

Acute Toxicity of Hexazinone Guideline No. Study Type MRIDs # Results Toxicity Category 81 1 Acute Oral/ Rat 41235004 (1989) LD50 = 1200 mg/ kg III 81 2 Acute Dermal/ Rabbit 00104974 LD50 >5278 mg/ kg IV 81 3 Acute Inhalation 41756701 (1991) LC50 > 3.94 mg/ L( 4 hour) III 81 4 Primary Eye Irritation 00106003 (1982) Irreversible corneal opacity, Severe I 81 5 Primary Skin Irritation 00106004 (1982) Mild IV 81 6 Dermal Sensitization 41235005 (1989) NA Not a skin sensitizer 4.2 Subchronic Toxicity Adequacy of data base for subchronic toxicity: The data base for subchronic toxicity is considered adequate for reregistration. Only a 28 day inhalation study is required at this time. HEXAZINONE/ 107201/ May/ 2002 TRED Toxicology Chapter 6 870.3100 90 Day Oral Toxicity  Rat EXECUTIVE SUMMARY: In this subchronic oral toxicity study (MRID 00104977), hexazinone (INA 3674; purity not provided; Lot/ Batch # not provided) was administered in the diet to 16 ChRCD rats/ sex/ group at nominal doses of 0, 200, 1000, or 5000 ppm (equivalent to 0/ 0, 16.0/ 16.4, 81.0/ 87.3, or 440.4/ 450.7 mg/ kg for males/ females) for 13 weeks. After 4, 8, and 13 weeks on the test diet, 10 of the 16 rats/ sex/ dose were subjected to hematology, clinical chemistry, and urinalysis tests. After 13 weeks, 10 rats/ sex/ group were sacrificed for necropsy and histopathological examination. The remaining 6 rats/ sex/ group continued on the test diet for at least 3 weeks in a onegeneration one litter reproduction study. There were no treatment related effects on mortality, clinical signs, food consumption, hematology, urinalysis, organ weights, or histopathology. No data were provided for gross pathology. In the 200 and 1000 ppm animals, all parameters examined were comparable to controls. Body weights were decreased in the 5000 ppm animals (94 15%) throughout the study. Likewise, overall body weight gains (calculated by the reviewers) were decreased in this group (98 20%). Although food consumption was comparable among treated animals and controls, overall (Days 0 91) mean food efficiency was decreased (statistics not performed) in the 5000 ppm males (911%) and females (915%) compared to controls. Food efficiency in males and females was unchanged for the first 28 days of the study. Males showed a 6% and 9% decrement for days 28 56 and days 56 91, respectively at 5000 ppm. Females showed a 25% and 64% decrement in food efficiency for the same respective days. The progressive nature of the reduced food efficiency, especially in females, supports a body weight decrement at 5000 ppm from toxicity. Alanine aminotransferase (ALT) was increased (statistics not performed) in the 5000 ppm females at 1 (863%), 2 (863%), and 3 (825%) months. However, because there were no treatmentrelated changes in liver weights or histology, increases in ALT were considered of equivocal toxicological significance. For all other clinical chemistry parameters examined, treatment groups were either comparable to controls, sporadic, or differences were not dose related. Additionally, in the one generation, one litter reproduction study, there were no treatmentrelated differences in pregnancy rate (fertility), gestation, number of pups born, pup viability, or lactation. However, the mean pup weight was lower (924%; statistics not performed) in the 5000 ppm group than in controls. The LOAEL for this study is 5000 ppm (equivalent to 440.4/ 450.7 mg/ kg/ day for male/ females) based on decreased body weights and food efficiency. The NOAEL is 1000 ppm (equivalent to 81.0/ 87.3 mg/ kg/ day for males/ females). The submitted study is classified as acceptable does satisfy the guideline (§ 82 1a; OPPTS 870.3100) requirements for a subchronic oral toxicity study in the rat.

870.3100 90 Day Oral Toxicity  Mouse No study is available. HEXAZINONE/ 107201/ May/ 2002 TRED Toxicology Chapter 7 870.3150 90 Day Oral Toxicity  Dog EXECUTIVE SUMMARY: In this subchronic oral study (MRID 00114484), hexazinone INA3674 97.5% a. i.; Lot/ Batch# not provided) was administered in the diet to 4 beagle dogs/ sex/ group at doses of 0, 200, 1000, or 5000 ppm (equivalent to 0/ 0, 5.1/ 7.0, 25.9/ 31.6, 122.5/ 137.3 mg/ kg/ day for males/ females) for 13 weeks. Homogeneity, concentration, and stability analyses were not performed on the test diets. No mortalities occurred during the study. Clinical signs and hematology were unaffected by the test substance. At 5000 ppm, the negative overall (Weeks 0 13) body weight gains show that these animals were unable to maintain body weight ( 0.9 kg in males, 0.3 kg in females). Food consumption was decreased in the females in this dose group at Weeks 1 (941%) and 2 (915%). In the males, food consumption was comparable among treated and control groups throughout the study. Findings in organ weights and clinical chemistry at 5000 ppm indicate liver toxicity as an effect of treatment. Absolute liver weights were increased in the males at 200 (810%), 1000 (821%), and 5000 (826%) ppm and in the females at 5000 (833%) ppm. However, relative liver weights were only increased at 5000 ppm in the males (827%) and females (840%), indicating the increases in absolute liver weights at 200 and 1000 ppm were most likely due to increased body weights in these animals compared to controls. Alkaline phosphatase levels were increased in the males and females in this dose group at 1 (846 75%), 2 (886 125%), and 3 (8124 214%) months. Serum levels of this enzyme increased as the study progressed. In the 5000 ppm males, proteinuria was observed at Months 2 and 3 (1/ 4 each treated vs 0/ 4 in any other dose group). Vacuolation of the cytoplasm of the cells lining the Loop of Henle was observed in the males (1/ 4 treated vs 0/ 4 controls) and females (1/ 4 treated vs 0/ 4 controls) in this dose group. The LOAEL was 5000 ppm (equivalent to 122.5/ 137.3 mg/ kg/ day in males/ females) based on decreased body weight gains, increased relative liver weights, and increased alkaline phosphatase levels in both sexes and transiently decreased food consumption in the females. The NOAEL for this study is 1000 ppm (equivalent to 25.9/ 31.6 mg/ kg/ day for males/ females). The submitted study is classified as acceptable and does satisfy the guideline (§ 82 1b; OPPTS 870.3150) requirement for a subchronic oral toxicity study in the dog. The deficiencies in the parameters reported did not appear to compromise the study results.

870.3200 21/ 28 Day Dermal Toxicity – Rat EXECUTIVE SUMMARY: In a repeated dose dermal toxicity study (MRID 41309005), groups of five male and five female New Zealand White rabbits received applications of 0, 50, 400, or 1000 mg/ kg/ day Hexazinone technical (> 98%, Lot No. T02118994) in distilled water, 6 hours/ day for 21 consecutive days. There were no treatment related deaths, clinical signs, hematological or clinical chemistry HEXAZINONE/ 107201/ May/ 2002 TRED Toxicology Chapter 8 effects, organ weight effects or gross or histopathological effects attributable to treatment. No treatment related body weight, food consumption, or food efficiency effects were observed. Treatment related dermal irritation was observed on rabbits in all treatment groups, including controls. Slight erythema was noted on 3/ 5 control females, 4/ 5 low dose males, 4/ 5 low dose females, and all mid and high dose males and females. Slight edema was noted on 1/ 5 control female, 1/ 5 high dose male, and 1/ 5 high dose female. These dermal effects were not considered toxicologically significant. The systemic and dermal NOAEL for Hexazinone technical in male and female rabbits is the limit dose of 1000 mg/ kg/ day. The systemic and dermal LOAEL were not identified. This study is classified as Acceptable/ Guideline and does satisfy the guideline requirements for a repeated dose dermal study [OPPTS 870.3200 (§ 82 2)] in rabbits.

870.3465 90 Day Inhalation – Rat No study is available. The HIARC determined that a 28 day inhalation study is required to address the concern for inhalation exposure due in part to the irritating properties of hexazinone. The Agency should be contacted prior to conducting this study.

4.3 Prenatal Developmental Toxicity Adequacy of data base for Prenatal Developmental Toxicity: The data base for prenatal developmental toxicity is not complete. The HIARC declared the Rabbit developmental toxicity study unacceptable/ upgradable. Another study is required. There was no quantitative or qualitative evidence of increased susceptibility following in utero exposure to the acceptable rat study or the unacceptable rabbit study. In rats, maternal toxicity was seen at a lower dose than developmental toxicity, and in rabbits, developmental effects may have been at the same dose level as maternal toxicity.

870.3700a Prenatal Developmental Toxicity Study  Rat EXECUTIVE SUMMARY: In a developmental toxicity study (MRID 40397501), hexazinone (99.26% a. i.; Lot# S30306A, Batch# 2/ 36) in 0.5% methylcellulose was administered orally via gavage to 25 Crl: CD ® BR female rats/ group at dose levels of 0, 40, 100, 400, or 900 mg/ kg on gestation day (GD) 7 through 16. The dosing volume was 10 mL/ kg (calculated by reviewers). All dams were sacrificed on GD 22 and their fetuses removed by cesarean and examined. When compared to concurrent controls, no treatment related changes in clinical signs, gross pathology, pregnancy rate, live fetuses, resorptions, pre or post implantation loss, corpora lutea, or implantations were noted at any dose level tested. No treatment related findings were noted in the 100, or 40 mg/ kg groups. HEXAZINONE/ 107201/ May/ 2002 TRED Toxicology Chapter 9 In the 900 mg/ kg dams, one treatment related death occurred; alopecia and an enlarged stomach containing fluid and food were noted at necropsy. Decreased (p< 0.05) body weight gains were noted during GDs 15 17 (937%) and 17 22 (917%). In addition, body weight gains were decreased (p< 0.05) for the overall (GDs 7 17) treatment interval (930%). Gravid uterine weights were not reported; however, adjusted (for gravid uterine weight) terminal body weights were slightly decreased (96%; p#0.05). A significant (p#0.05) trend by linear combination of dose ranks from ANOVA was noted for GDs 9 11, 15 17, 7 17, and 17 22. Decreased (p#0.05) food consumption was observed throughout treatment (GDs 7 17; 916 22%) and post treatment (GDs 17 22; 99%). A significant (p#0.05) trend by linear combination of dose ranks from ANOVA was noted for GDs 7 9, 9 11, 11 13, 13 15, 15 17, 7 17, and 17 22. Also a significantly decreased food consumption was seen at 400 mg/ kg/ day (GD9 11; 91%) and (GD 7 17; 98%). In addition, relative (to body) liver weights were increased (p#0.05) in the 400 (5.2%) and 900 (5.6%) mg/ kg dams compared to concurrent controls (4.9%). Decreased (p#0.05) terminal body weights were noted at 900 mg/ kg (96%). A significant (p#0.05) trend by linear combination of dose ranks from ANOVA was noted for relative liver weights and adjusted terminal body weights. In addition, a significant (p#0.05) trend by linear combination of dose ranks from ANOVA was noted for absolute liver weights. Despite this trend, the observed increases in absolute liver weights at 100, 400, and 900 mg/ kg (81 8%) were not statistically significant. Liver weight findings are considered equivocal. The maternal LOAEL is 400 mg/ kg/ day based on decreased food consumption during dosing and nominal decreases in body weight gain from day 7 to day 17 and at all measured intervals between and at 900 mg/ kg/ day on mortality and decreased body weight gains and food consumption. The maternal NOAEL is 100 mg/ kg/ day. In the 900 mg/ kg/ day group, male and female fetal weights were decreased (921%; p#0.05); a significant (p#0.05) trend by Jonckheere's test was noted for this parameter. At 400 mg/ kg/ day, only female fetal weights were significantly decreased by 2% (insufficient to be considered an effect). At necropsy, an increased (p#0.05) incidence of misaligned sternebrae (1), a variation, was observed (fetal incidence: 0.0217; litter incidence: 0.30) relative to concurrent controls (fetal incidence: 0.0066; litter incidence: 0.09). In addition, an increased (p#0.05) incidence of misaligned sternebrae (2+), a variation, was noted (fetal incidence: 0.0217; litter incidence: 0.30) relative to concurrent controls (fetal incidence: 0.0033; litter incidence: 0.04). Furthermore, an increased incidence of kidneys with no papilla was observed (fetal incidence: 0.0347; litter incidence: 0.25) relative to concurrent controls (fetal incidence: 0.0062; litter incidence: 0.04). Although the incidence was not statistically significant, a dose related trend (p#0.05) was observed. The developmental toxicity LOAEL is 900 mg/ kg/ day based on decreased male and female fetal weight, increased incidence of kidneys with no papilla (malformation), and an increased incidence of misaligned sternebrae (variation). The developmental toxicity NOAEL is 400 mg/ kg/ day. The developmental toxicity study in the rat is classified acceptable/ guideline (OPPTS 870.3700; §83 3 a) and satisfies the guideline requirement for a developmental toxicity study in the rat. HEXAZINONE/ 107201/ May/ 2002 TRED Toxicology Chapter 10 870.3700a Prenatal Developmental Toxicity Study  Rat EXECUTIVE SUMMARY: In a developmental toxicity study (MRID 00114486), hexazinone (97.5% a. i.; Code# INA 3674 19, Lot/ Batch# N. B. 6849 30 [6842 29]; no further information provided) was administered orally in the diet to 25 27 ChR CD female rats/ group at dose levels of 0, 200, 1000, or 5000 ppm (equivalent to 0, 18.9, 94.5, and 482.0 mg/ kg) on GD 6 through 15. All dams were sacrificed on GD 21 and their fetuses removed by cesarean and examined. When compared to concurrent controls, no treatment related changes in food consumption, or number of implantations, live fetuses, dead fetuses, or premature deliveries were noted. It was stated that no treatment related changes in mortality, clinical signs, or gross pathology were observed; however no data were provided. Gravid uterine weights were not reported. Sex ratios, the number of corpora lutea, pre implantation loss, and post implantation loss were not reported and could not be calculated without individual data (not provided). Throughout the study, standard deviations were not calculated, individual data were not provided, and statistical analyses were not performed. Mean body weight gains and food efficiency were decreased during treatment (GDs 6 16). At 5000 ppm, mean body weight gains were decreased by 74% compared to concurrent controls. In addition, food efficiency during the treatment interval was 0.84 (vs. 3.0 in controls). At 5000 ppm, markedly decreased body weights were observed at GDs 16 (919%) and 21 (912%). Additionally at 5000 ppm, the number of females showing partial resorption (excluding complete resorptions) was 56.5%. This incidence exceeded the concurrent control incidence (39.1%); however, it was within the range of historical controls (mean was 40.6%, range was10.5 77.8%). The maternal LOAEL is 5000 ppm (equivalent to 482 mg/ kg/ day) based on decreased body weights, body weight gains, and food efficiency. The maternal NOAEL is 1000 ppm (equivalent to 94.5 mg/ kg/ day). No treatment related findings were noted in the fetuses at 200, 1000, or 5000 ppm. The developmental toxicity LOAEL was not observed. The developmental toxicity NOAEL is 5000 ppm (equivalent to 482.0 mg/ kg/ day). This developmental toxicity study in the rat is classified unacceptable/ upgradable pending submission of the following information:

 Individual maternal and fetal data  Statistical analyses of the data  Environmental conditions of the testing laboratory  Gross pathology data.  Sex ratios, the number of corpora lutea, pre implantation loss, and post implantation loss  Litter incidence for fetal necropsy findings  Clinical signs and mortality data HEXAZINONE/ 107201/ May/ 2002 TRED Toxicology Chapter 11 870.3700b Prenatal Developmental Toxicity Study  Rabbit EXECUTIVE SUMMARY: In a developmental toxicity study (MRID 00028863), hexazinone (100% a. i.; Lot/ batch # E21216A) was administered orally via gavage in a dosing volume of 1 mL/ kg) to 17 female New Zealand White rabbits/ group at dose levels of 0, 20, 50, or 125 mg/ kg on GD 6 through 19. All does (except those that died or delivered prematurely) were sacrificed on GD 29, and their fetuses removed by cesarean and examined. When compared to concurrent controls, no treatment related changes in mortality, clinical signs, body weights, gross pathology, fetal weights, sex ratios, pre implantation or post implantation losses, or the number of corpora lutea, implantations, resorptions, live fetuses, or dead fetuses were observed. At 125 mg/ kg, food consumption was decreased (p#0.05), relative to concurrent controls, at the beginning of treatment from GD 7 through 11 (961 89%). Decreases in food consumption, that were not statistically significant, continued throughout treatment (GDs 12 19; 92 37%). Diminished food consumption resulted in decreased (not statistically significant) body weight gains in the does 241.5 g) relative to concurrent controls ( 7.2 g) during GDs 6 11. However, weight gain in these animals recovered quickly and was higher than control animals during subsequent treatment intervals (GDs 11 15 and 15 19). The maternal LOAEL is 125 mg/ kg/ day based on transient decreases in food consumption and body weight gains. The maternal NOAEL is 50 mg/ kg/ day. At 125 mg/ kg/ day, the following skeletal variations were noted (data presented as fetal incidence vs. 0 controls): (i) lagging ossification in extremities (0.0882); (ii) malaligned thoracic vertebrae (0.0294); and (iii) flexed wrist( s) (0.0294). In addition, non ossified thumb, an anomaly, was noted at an increased incidence (0.0294) relative to concurrent controls (0). In the absence of historical control data, these findings are considered treatment related. In addition, it could not be determined how many of these nominally increased incidences were from different litters, which would have increased concern for developmental toxicity. The developmental toxicity LOAEL is 125 mg/ kg/ day, based on possible skeletal abnormalities and total abnormalies. The developmental toxicity NOAEL is 50 mg/ kg/ day. The developmental toxicity study in the rat is classified unacceptable/ upgradable, pending submission of acceptable purity, concentration, stability and litter data and historical control data. A letter dated 9/ 26/ 01 from the registrant provided no additional information about this rabbit developmental toxicity study other than the doses were not analyzed and that a repeat rabbit developmental toxicity was currently being conducted.

4.4 Reproductive Toxicity Adequacy of data base for Reproductive Toxicity: The data base for reproductive toxicity is considered complete. No additional studies are required at this time. There was no evidence of qualitative or quantitative susceptibility in a two generation study HEXAZINONE/ 107201/ May/ 2002 TRED Toxicology Chapter 12 of reproduction.

870.3800 Reproduction and Fertility Effects  Rat Executive Summary: In a two generation reproduction study, hexazinone (98% a. i., Lot No. T02118994) was administered to groups of 30 male and 30 female Sprague Dawley rats in the diet at concentrations of 0, 200, 2000, or 5000 ppm (MRID 42066501). One litter was produced in the first generation and two litters were produced in the second generation. Test substance intake for the treated F0 groups was 11.8, 117, and 294 mg/ kg/ day, respectively, for males and 14.3, 143, and 383 mg/ kg/ day, respectively, for females. Test substance intake for the treated F1 groups was 15.3, 154, and 399 mg/ kg/ day, respectively, for males and 17.7, 180, and 484 mg/ kg/ day, respectively, for females. F0 and F1 parental animals were administered test or control diet for 73 or 105 days, respectively, prior to mating, throughout mating, gestation, and lactation, and until necropsy. Deaths of several F0 and F1 parental animals were considered incidental to treatment. No treatment related clinical signs of toxicity were observed in the adult animals of either generation. Gross necropsy was unremarkable and no microscopic lesions were observed in selected tissues from the reproductive tracts of male and female parental animals. Body weights and body weight gains of the F0 males were not affected by treatment. Premating body weight gains by the mid and high dose F0 females were 76% and 62% (p # 0.05 for both), respectively, of the control level resulting in final premating body weights 93% and 87% (p # 0.05), respectively, of the controls. Body weights of the high dose F1 males and females were significantly reduced (p # 0.05) during the premating interval with overall weight gains 87% and 82%, respectively, of the control group amounts. Reductions in body weights and body weight gains during premating for the mid and high dose F0 and high dose F1 dams continued during gestation and lactation. Food consumption during premating was similar between the treated and control groups for males and females of both generations. However, during gestation significantly (p # 0.05) lower food consumption was noted for the high dose F1 dams during production of both litters and for the middose F1 dams during production of the second litter. There was a statistically significant increase in absolute P0 testes weight that appeared to be dose related, but a nominally decrease absolute F1 adult testes weight in the 5000 ppm dose groups. The F1 testes weight change did not appear to dose related. The testes weight changes in males would appear to be incidental. Therefore, the systemic toxicity LOAEL is 2000 ppm (117 154 mg/ kg/ day for males and 143 180 mg/ kg/ day for females) based on reduced body weight and body weight gains by F1 males and F0 and F1 females. The systemic toxicity NOAEL is 200 ppm (11.8 15.3 mg/ kg/ day for males and 14.3 17.7 mg/ kg/ day for females). No reproductive effects were seen in the study except for the weight effects on offspring. Live birth and viability indices and litter survival were similar between the treated and control groups. The lactation index for the F2b high dose litters was 85.8% (p # 0.05) compared to 97.5% for the control group. Pup body weights were decreased throughout lactation in the mid and high dose groups of all litters as compared with the control groups with statistical significance (p # 0.05) attained HEXAZINONE/ 107201/ May/ 2002 TRED Toxicology Chapter 13 at most time points. The lower pup body weights were more pronounced in females than in males. F1 and F2a female pup weights were statistically significantly decreased at birth, day 7 and 14 of lactation at $2000 ppm. There were no obvious reproductive effects other than the pup weight decrement. Therefore, the offspring LOAEL is 2000 ppm (117 154 mg/ kg/ day for males and 143 180 mg/ kg/ day for females) based on reduced female pup body weights at birth and during lactation. The reproductive toxicity NOAEL was 200 ppm (11.8 15.3 mg/ kg/ day for males and 14.3 17.7 mg/ kg/ day for females). This study is classified as Acceptable/ Guideline and satisfies the guideline requirements for a reproductive toxicity study [OPPTS 870.3800 (§ 83 4)] in rats.

4.5 Chronic Toxicity Adequacy of data base for chronic toxicity: The data base for chronic toxicity is considered complete. No additional studies are required at this time. The chronic study in dogs showed severe body weight decrement, changes in liver related clinical chemistry values, and microscopic lesions. Body weight decrement was seen in a chronic carcinogenicity studies in rats and mice. Liver toxicity was seen in mice.

870.4100a Chronic/ Carcinogenic Toxicity  Rat See Section below on Carcinogenicity study in rats (870.4300 Chronic/ Carcinogenicity in rats).

870.4100b Chronic Toxicity  Dog EXECUTIVE SUMMARY: In a one year chronic toxicity study, hexazinone (98% a. i., Lot No. T02118994) was administered to groups of 5 male and 5 female beagle dogs in the diet at concentrations of 0, 200, 1500, or 6000 ppm (MRID 42162301). Time weighted average doses for the treated groups were 5.00, 41.24, and 161.48 mg/ kg/ day, respectively, for males and 4.97, 37.57, and 166.99 mg/ kg/ day, respectively, for females. All animals survived to scheduled necropsy. Treatment related clinical signs of toxicity included the observation of thinness in 1/ 5 mid dose males, 3/ 5 high dose males, and 1/ 5 high dose females. Body weights of the high dose groups were significantly (p # 0.05) less than those of the control throughout most of the study. Final body weights of the high dose males and females were 78% and 67%, respectively, of the control levels. Food consumption by the high dose groups was slightly (n. s.) less than that of the controls throughout the study with statistical significance (p # 0.05) attained for females at week 52. Overall food consumption (weeks 1 52) for high dose males and females was 85% (n. s.) and 74% (p # 0.05), respectively, of the control group levels. Body weights HEXAZINONE/ 107201/ May/ 2002 TRED Toxicology Chapter 14 and food consumption for the low and mid dose groups were not affected by treatment. No treatment related ophthalmological lesions, changes in urinalysis parameters, or gross necropsy findings were noted. A moderate macrocytic anemia was observed in the high dose groups as evidenced by slight or significant (p # 0.05) decreases in RBC counts, hemoglobin, and hematocrit and increases in MCV and MCH in one or both sexes throughout the study. Cholesterol levels were significantly (p # 0.05) decreased in the high dose groups beginning at week 13 for males (52 64% of controls) and at week 26 for females (45 51% of controls). Albumin levels were significantly (p # 0.05) decreased in the mid dose males (93% of controls) at week 13 only, and in the high dose males (74 78% of controls) and females (75 82% of controls) throughout the study. Beginning on week 13 or 26, the high dose groups had aspartate aminotransferase levels 140 203% (p # 0.05) of the control values and alanine aminotransferase levels 206 276% (p # 0.05) of the control values. Alkaline phosphatase levels were significantly (p # 0.05) increased in the mid dose males (259 409% of controls) and females (163 194% of controls; n. s.) beginning at week 26 and in the high dose males (346 1363% of controls) and females (307 559% of controls) beginning at week 13. For the high dose animals, decreases in absolute testes weights in males and kidney, heart, and brain weights in females ( 12%) and increases in relative liver weights in males and females were considered due to lower final body weights of these animals as compared with controls. Microscopic lesions in the liver of high dose animals included concentric membranous bodies in 4 males and 5 females, centrilobular single cell necrosis in 3 males and 3 females, hepatocellular pigment in 3 males and 3 females, and vacuolation in 3 males and 4 females. In addition vacuolation was observed in one mid dose male and pigment and membranous bodies were each observed in one mid dose female. These lesions were not seen in control or low dose animals. Therefore, the LOAEL for hexazinone in male and female beagle dogs is 1500 ppm (41.24 and 37.57 mg/ kg/ day, respectively) based on thinness in one male and hepatotoxicity as evidenced by changes in clinical chemistry parameters and microscopic lesions. The NOAEL is 200 ppm (5.00 and 4.97 mg/ kg/ day, respectively). This study is classified as Acceptable/ Guideline and satisfies the guideline requirements for a chronic toxicity study [OPPTS 870.4100 (§ 83 1b)] in dogs.

4.6 Carcinogenicity Adequacy of data base for Carcinogenicity: The data base for carcinogenicity is considered complete. No additional studies are required at this time. HED's Carcinogenicity Peer Review Committee classified hexazinone as a Group D chemical (not classifiable as to human carcinogenicity) (7/ 27/ 94). This classification was based on the following weight of evidence considerations. In rats, females showed no evidence for carcinogenicity; males showed a significant trend only for thyroid adenomas. In mice, the evidence of carcinogenicity was equivocal: a positive trend test for liver tumors was observed only in female mice, but no significant difference was seen by pair wise comparison (CPRC Report dated July 27, 1994). HEXAZINONE/ 107201/ May/ 2002 TRED Toxicology Chapter 15 870.4200b Carcinogenicity (feeding)  Mouse EXECUTIVE SUMMARY: In this mouse oncogenicity study (MRIDs 00079203, 41359301, 42509301 and 43202901), hexazinone ($95% a. i.; Lot/ Batch #: H 11, 265 and 265 2) was administered in the diet to CD 1 mice (80/ sex/ group) for up to 104 weeks at nominal doses of 0, 200, 2500 or 10,000 ppm (equivalent to 28, 366 and 1635 mg/ kg/ day in males and 0, 34, 450 and 1915 mg/ kg/ day in females). No treatment related differences were observed in mortality, food consumption, food efficiency or hematology. Hepatotoxicity was evident at the terminal sacrifice. Macroscopic liver nodule/ mass (% treated vs % controls; n = 28 55) was observed in males at 2500 (39% vs 7%) and 10,000 ppm (33%). Increased incidences (% treated vs 0% controls; n = 38 55) in the following microscopic liver lesions were observed: hyperplastic nodule( s) (includes both foci of cellular alteration and adenoma) in males at 2500 (39% vs 20%) and 10,000 ppm (36%) and in females at 10,000 ppm (15% vs 3%); and necrosis (severity and type unspecified) in the 10,000 ppm males (36% vs 7%). Centrilobular hepatocyte hypertrophy was observed (% treated vs % controls) at the terminal sacrifice (n = 38 55) in males at 2500 (18% vs 0%) and 10,000 ppm (98%) and in females at 10,000 ppm (46% vs 0%) and in the dead and moribund males (n = 25 40) at 2500 (44% vs 0%) and 10,000 ppm (60%). Increased (p#0.05 or 0.01) liver/ gall bladder weights were observed at 10,000 ppm in males in both absolute and relative to body weights and in females in relative to body weight. Other signs of toxicity were evident. Distal tail tip sloughing and/ or discoloration was observed at 10,000 ppm in males at Weeks 13 104 and in females at Weeks 5 and 13 104. Macroscopically, tip of tail missing/ sloughed was observed at the terminal sacrifice in the 10,000 ppm males (31% vs 5%) and females (61% vs 11%) and in the dead and moribund 10,000 ppm females (46% vs 2%). The toxicological significance of these findings was unclear. Minor decreases (p#0.05 or 0.01) in body weights were observed in the 10,000 ppm treatment groups at Weeks 13 104 in both sexes. Overall body weight gains (calculated by the reviewers) were decreased in the 10,000 ppm males (925%) and females (931%). The LOAEL is 2500 ppm for males (equivalent to 366 mg/ kg/ day) based on gross liver nodules/ masses, hyperplastic nodules in the liver and centrilobular hepatocyte hypertrophy and 10,000 ppm for females (equivalent to 1915 mg/ kg/ day [limit dose]) based on decreased body weights, increased relative liver/ gall bladder weights, hyperplastic nodules and centrilobular hepatocyte hypertrophy. The NOAEL is 200 ppm (equivalent to 28 mg/ kg/ day) for males and 2500 ppm (equivalent to 450 mg/ kg/ day) for females. Liver samples were first evaluated using the term hyperplastic nodule which did not clearly distinguish neoplasia from non neoplasia. Re evaluation was conducted to make this distinction, and no significant differences were observed between the treatment groups and the concurrent controls. However positive trends (p< 0.05) were observed (% treated vs % controls) in focus/ foci of cellular alteration in males, hepatocellular neoplasm( s) (including adenoma, sarcoma, carcinoma, leukemia, and HEXAZINONE/ 107201/ May/ 2002 TRED Toxicology Chapter 16 lymphoma) in females, and singular hepatocellular adenoma in females. Focus/ foci of cellular alteration were observed in males at 2500 (11.3% vs 5.0%) and 10,000 ppm (24.1%) and females at 10,000 ppm (12.5% vs 3.8%) beginning at Week 57. Singular hepatocellular adenoma was observed in the 10,000 ppm females (7.5% vs 2.5%) beginning at Week 77. Hepatocellular neoplasm( s) were observed in the 10,000 ppm females (8.8% vs 2.5%). A carcinoma in the 10,000 ppm treatment groups was first observed at Week 65. The incidence of carcinomas were within historical control ranges for each sex, while the incidence of adenomas were increased by 3.21% in the 10,000 ppm females. A dose dependent increase in adenomas was not observed in males. The Health Effects Division Carcinogenicity Peer Review Committee (CPRC) concluded that hexazinone should be classified as a Group D (not classifiable as to human carcinogenicity)( 7/ 27/ 94). Under the conditions of this study, evidence of carcinogenic potential was equivocal: a positive trend test for neoplasia was observed in female mice, but no significant difference was determined by pair wise comparison.

The submitted study is classified as acceptable for guideline 870 4200 carcinogenicity study in mice.

870.4300 Chronic/ Carcinogenicity Study  rat EXECUTIVE SUMMARY: In this combined chronic/ oncogenicity study (MRID 00108638), hexazinone (94 96% a. i.; Lot/ Batch #: 6897 40 and 74.25) was administered in the diet to ChR CD rats (36/ sex/ group) for up to 25 months at nominal doses of 0, 0, 200, 1000, or 2500 ppm (equivalent to 0, 0, 10.2, 53.4, and 138.3 mg/ kg/ day in males and 0, 0, 12.5, 67.5, and 178.6 mg/ kg/ day in females). No treatment related differences were observed in mortality, clinical signs, food consumption, hematology, clinical chemistry, organ weights, and gross or microscopic pathology. No adverse effects were observed in the 200 ppm animals. There were several signs of general toxicity, but a target organ could not be clearly identified at any dose. Terminal body weights were decreased 8% in1000 ppm and 20%, p#0.05, in the 2500 ppm females. A decrease in overall body weight gain (Days 0 728; calculated by the reviewers) was also observed in the 1000 ( 10%) and 2500 ppm ( 25%) females. Nominal decreases in body weight and body weight gain ( 3 to 5%) occurred in males at 1000 ppm during the study, which may have been biologically significant at the end of the study ( 12% body weight and 14% for body weight gain). Decreases (p values not calculated) in total food efficiency were observed in females at 1000 ( 10%) and 2500 ppm ( 25%) and in males at 1000 ppm during the study with overall decrement in food efficiency in 1000 ppm males ( 10%). In males at 2500 ppm, food efficiency was depressed for the first 6 months of the study ( 25%), but from 6 months to the end of the study, it was increased 139%. The reviewer noted problems interpreting the body weights and food efficiency in males at the top dose level, which were not consistent with the mid dose level. For the first 6 months of the study in males, a body weight decrement due to probable toxicity was seen at 1000 and 2500 ppm. HEXAZINONE/ 107201/ May/ 2002 TRED Toxicology Chapter 17 After 6 months food efficiency in males at the 1000 ppm remained less than controls ( 56%) while food efficiency at 2500 ppm in males was higher than controls (+ 139%)( Table 4). By the end of the study, male body weight at 1000 ppm was 12% and body weight gain 14%, where as body weight and body weight gain in males at 2500 ppm was +3% for both weight and gain. The reason for this recovery in male body weight decrement at 2500 ppm is unknown, but it appears to be real. [Since absolute and relative liver weights were decreased in males at 2500 ppm, liver enzyme induction allowing the recovery seems unproven.] The body weight decrement at 1000 and 2500 ppm with recovery in body weight at 2500 ppm indicates the an adequate dose level to test for carcinogenicity in males was approached, but probably not attained. Other treatment groups were similar to the average of concurrent controls. Dosing was considered adequate based on decreased body weights, body weight gains, and food efficiency in the 2500 and 1000 ppm females and food efficiency and body weights in the 2500 ppm males for the first 6 months. Body weight ( 12%) and body weight gain 14 in males at 1000 ppm were decreased at the end of the study, in addition overall food efficiency ( 14%) was decreased by the end of the study. Thus female body weight and body weight gain was decreased sufficiently to adequately test for carcinogenicity. Male body weight and body weight gain at 1000 ppm appeared to be adequate to test for carcinogenicity by the end of the study, but the lack of dose response in male body weight and body weight gain at 2500 ppm (showing recovery after 6 months such that body weight and body weight gain were higher than control values) may indicate problems with the interpretation of the body weights and body weight gains at 1000 ppm. In the 2500 ppm males, creatinine was increased (NS) in the urine at months 18 and 24 and bilirubin was detected at month 18 and 24. The Sponsor reported that the urine was more alkaline in the 2500 ppm treatment groups (data not reported). Also at 2500 ppm, decreased (p#0.05) absolute and relative liver and kidney organ weights were observed in the males and increased (p#0.05) relative (to body) stomach and kidney organ weights were observed in the females. However, histopathological data did not corroborate these findings. The LOAEL is 1000 ppm for males and females (equivalent to 53.3 for males and 67.5 mg/ kg/ day for females) based on decreased body weight and food efficiency in males and females. In males at 2500 ppm the body weight decrement and food efficiency decrement occurred only for the first 6 months of the study. The NOAEL is 200 ppm for males and females (10.2 for males and 12.5 mg/ kg/ day for females). Neoplasm data were evaluated by two pathologists. An increase incidence of thyroid Ccell adenomas was observed in the 2500 ppm males, but when analyzed by the Fisher's exact test (p> 0.10) or life table methods (p> 0.20) no significant differences were observed between controls and treated groups. Using life table analyses a significant (p< 0.05) dose response trend was observed in thyroid C cell tumors in only one of the two pathology reports. Female rats did not show any potential for C cell thyroid adenomas. The incidence, malignancy and latency of tumors were comparable among control and treated rats of both sexes. Under the conditions of this study, carcinogenic potential of hexazinone is considered negative. The submitted study is classified as acceptable for guideline 870.4300 combined HEXAZINONE/ 107201/ May/ 2002 TRED Toxicology Chapter 18 chronic/ carcinogenicity study in rats.

4.7 Mutagenicity Adequacy of data base for Mutagenicity: The data base for Mutagenicity is considered adequate based on pre 1991 mutagenicity guidelines. Hexazinone was found to be positive for mutagenicity in one chromosomal aberration assay (in vitro cytogenics) (MRID# 00130709), but negative in the remaining studies. It is concluded that the test material was clastogenic in both of the non activated trials and was also clastogenic in the one adequate S9 activated trials. Under both test conditions, concentrations providing evidence of clastogenicity induced an acceptable level of cytotoxicity (> 50% relative cell survival). Thus, the findings can not be considered to be a secondary effect of cytotoxicity. Nevertheless, the outcome of the induced structural damage (i. e., primarily chromatid and chromosome breaks) is unclear since these types of structural aberrations would not likely be passed on to daughter cells. Because unambiguous positive results were achieved, it was concluded that the study provided adequate evidence that INA3674 112 (hexazinone, technical) is clastogenic in an acceptable study.

Gene Mutation 4.7.1 Guideline 870.5100, Reverse mutation in Salmonella EXECUTIVE SUMMARY: In a reverse gene mutation assay in bacteria (MRID 40826201), strains TA98, TA100, TA1535, TA1537 and TA1538 of S. typhimurium were exposed to S triazine2,4 1H, 3H) dione, 3 cyclohexyl 6 dimethylamino 1 methyl (95% a. i.) in ethanol at concentrations of 200, 400, 600, 800 and 1000 :g/ plate without mammalian metabolic activation (S9 mix) and at concentrations of 400, 800, 1200, 1600 and 2000 :g/ mL with S9 mix. The S9 fraction was obtained from Aroclor 1254 induced male Crl: CD( SD) BR rat liver. The maximum concentrations of S triazine 2,4( 1H, 3H) dione, 3 cyclohexyl 6 dimethylamino 1 methyl tested produced little or no cytotoxicity, were not limited by solubility and were not a limit dose for the assay. No statistically significant increases in the number of revertants per plate or positive linear dose response were seen. The solvent and positive controls induced acceptable responses in the corresponding strains. There was no evidence of induced mutant colonies over background. This study is classified as Unacceptable. It does not satisfy the requirement for FIFRA Test Guideline [OPPTS 870.5100 (§ 84 2)] for in vitro mutagenicity [bacterial reverse gene mutation] data and should have used higher doses. HEXAZINONE/ 107201/ May/ 2002 TRED Toxicology Chapter 19 4.7.2 Guideline 870.5300, Gene mutation at HGPRT locus EXECUTIVE SUMMARY: In a mammalian cell gene mutation assay at the HGPRT locus (MRID No. 00076956), Chinese hamster CHO K1 BH4 cells cultured in vitro were exposed to INA 3674 112, (Lot No. 7612 5E6E, 95% a. i.) in ethanol in two trials. Concentrations used in Trial 1 were 2.0, 11.1, 13.1, 13.9 and 14.3 mM under nonactivated conditions and concentrations of 2.0, 7.9, 8.9, 9.3 and 9.9 mM under activated conditions (S9 mix). Concentrations used in Trial 2 were 2.0, 5.9, 11.1, 13.1 and 13.9 mM without S9 mix and concentrations of 2.0, 7.9, 8.9, 9.3 and 9.9 mM with S9 mix. The S9 fraction was obtained from Aroclor 1254 induced male Charles River CD® rat livers. INA 3674 112 was tested up to cytotoxic concentrations. In Trial 1, the cultures treated at 14.3 mM were not plated for mutation determination due to cytotoxicity and in both Trials 1 and 2, those cultures treated at 13.9 mM were excluded from analysis because no mutants were seen. No statistically significant increases in mutant frequency over solvent control values were seen with or without S9 mix in either Trial 1 or 2. The expected marked increase in the mutation were seen with the positive controls. There was, however, no indication that INA 3674 112 induced a mutagenic effect either in the presence or the absence of S9 activation. This study is classified as acceptable. It satisfies the requirement for FIFRA Test Guideline OPPTS [870.5300 (§ 84 2)] for in vitro mutagenicity (mammalian forward gene mutation) data.

4.7.3 Guideline: 870.5375: In vitro mammalian cytogenics (chromosomal aberrations) in Chinese hamster CHO cells.

EXECUTIVE SUMMARY: In a mammalian cell cytogenetics assay (MRID No. 00130709), Chinese hamster ovary CHO K1 BH4 cell cultures were exposed to INA 3674 112 (Hexazinone, 95% a. i.) in ethanol in two separate trials. Exposure was for two hours with activation and for 10 hours without activation. Cells were harvested 10 hours after the start of treatment. In Trial 1, cells were treated at concentrations of 1.58, 3.94, 15.85 and 19.82 mM without metabolic activation (S9 mix) and at concentrations of 0.32, 3.17, 7.93 and 15.85 mM with S9 mix. In Trial 2, cells were treated at concentrations of 1.58, 3.94, 7.93 and 15.85 without S9 mix and at concentrations of 0.32, 3.17, 7.93 and 15.85 mM with S9 mix. The S9 fraction was obtained from Aroclor 1254 induced CD rat livers. INA 3674 112 was tested up to cytotoxic concentrations. Based on the results of a preliminary cytotoxicity test, upper concentrations of 23.78 mM without S9 mix and 47.56 mM with S9 mix were selected for the first cytogenetic assay but these concentrations proved excessively cytotoxic and were not scored for chromosomal aberrations. Without S9 activation, statistically significant increases (p< 0.01) in structural aberrations per cell (excluding gaps), lesions per cell and percent abnormal cells were seen at 15.85 mM (Trials 1 and 2) and 19.82 mM (tested in Trial 1 only). Relative percent survival (RPS) at this level was .50%. The percent abnormal cells averaged over all cultures from both trials was 28.0% and 21.5% at 19.82 and 15.85 mM, respectively, compared to the solvent control values of 2.0% (0.5% ethanol in Trial 2) and 7.0% (0.75% ethanol in Trial 1). The percent abnormal cells in positive control cultures was 18% in both Trial 1 (4.83 mM EMS) and Trial 2 (6.44 mM EMS). In the presence of S9 mix, no statistically significant increases in chromosomal HEXAZINONE/ 107201/ May/ 2002 TRED Toxicology Chapter 20 aberration induction were seen in Trial 1; however, very low positive control values indicated a problem with the S9 mix. Statistically significant increases were seen at 15.85 mM in Trial 2; RPS at 15.85 mM was 75%. There was a statistically significant dose related trend for all three parameters. The statistically significant (p <0.01) increases at 15.85 mM remained when the data from Trial 1 and 2 were combined (average of 20% abnormal cells compared to 10% for the solvent control). The predominant aberrations with or without S9 mix were chromatid and isochromatid breaks. Solvent and positive controls (except the positive control in Trial 1 with S9 mix) induced the appropriate responses. INA 3674 112 was positive for the induction of structural chromosomal aberrations in both the presence and absence of S9 mix.

This study is classified as Acceptable/ guideline and satisfies the requirement for FIFRA Test 4.7.4 Guideline 870.5385: In vivo cytogenics assay in rat bone marrow cells EXECUTIVE SUMMARY: In a mammalian cell cytogenetics assay (MRID 00131355), in bone marrow cells of Sprague Dawley CD rats, three rats/ dose/ sex/ harvest time were exposed to H# 14,555 in corn oil ( assumed 100% a. i.) at doses of 100, 300 and 1000 mg/ kg by oral gavage. Bone marrow cells were harvested at 6, 12, 24 and 48 hours post treatment. The highest dose tested (1000 mg/ kg) was lethal. A major limitation of this study was the number of animals treated and the number of cells analyzed per animal. At most, three rats/ sex/ dose/ harvest time were treated with, at most, 50 cells per rat analyzed. Few or no analyzable cell were available from many rats. Positive control values were significantly (p= 0.03) increased. There was no evidence that H# 14, 14,555 induced an increase in the incidence of chromosomal aberrations in the bone marrow cells of treated animals. This study is classified as Unacceptable. The number of cells analyzed and the number of rats treated was insufficient. The study does not satisfy the requirement for FIFRA Test Guideline [OPPTS 870.5385 (§ 84 2)] for in vivo cytogenetic mutagenicity data.

4.7.5 Guideline 870.5395: Micronucleus assay in mouse bone marrow EXECUTIVE SUMMARY: In a Crl: CD 1 (ICR) BR mouse bone marrow micronucleus assay (MRID 45124401), 5 mice/ sex/ dose/ harvest time were treated orally with Hexazinone 25L (Lot No. 9912033, 25% Hexazinone a. i. (24.5% by analysis) and 75% inert ingredients) at doses of 1000, 2000 and 3000 mg/ kg. Bone marrow cells were harvested at 24 and 48 hours post treatment and examined for micronucleated polychromatic erythrocytes (MPCEs). The vehicle was Milli Q ® water. Signs of toxicity noted at 3000 mg/ kg included: death, convulsions, half shut eyes, head tilt, irregular respiration, lethargy, low carriage, pallor, prostration, uncontrollable spinning, shovel nosing, straining up on toes and tremors. Micronuclei were scored in bone marrow from mice treated at 3000 mg/ kg and from the solvent and positive controls. Mice from the two lower dose groups were not evaluated for micronuclei induction. No statistically significant increases in the frequency of MPCEs or HEXAZINONE/ 107201/ May/ 2002 TRED Toxicology Chapter 21 in the PCE/ NCE ratio over the solvent control values were seen in either sex at either the 24 or 48 hour harvest time. The solvent and positive control values were appropriate and within the testing laboratory's historical control ranges. There was no evidence that Hexazinone 25L induced a clastogenic or aneugenic effect in bone marrow at any harvest time. This study is classified as Acceptable/ Guideline. It satisfy the requirement for FIFRA Test Guideline [OPPTS 870.5395 (§ 84 2)] for in vivo cytogenetic mutagenicity data.

4.7.6 Guideline 8760.5550: Unscheduled DNA synthesis assay in rat hepatocytes EXECUTIVE SUMMARY: In an unscheduled DNA synthesis assay (MRID 00130708), primary rat hepatocyte cultures were exposed to INA 3674 112 (Lot No. 7612 5E6E, 95% a. i.) in ethanol for 18 hours at concentrations of 1 x 10 5 , 1 x 10 4 , 1 x 10 3 , 1 x 10 2 , 0.1, 1.0, 10.0 and 30.0 mM in Trial 1 and at concentrations of 1 x 10 5 , 1 x 10 4 , 1 x 10 3 , 1 x 10 2 , 0.1, 1.0, 5.0, 10.0 and 30.0 mM in Trial 2. INA 3674 112 was tested up to the highest achievable concentration in the solvent. Two slides per dose, 25 cells per slide were evaluated for UDS induction in Trial 1. One slide per dose, 25 cells per slide were evaluated in Trial 2. The author did not report that the slides were coded prior to analysis. The average net nuclear grain counts of test material treated cells in Trial 1 were all less than zero with the exception of one slide at 1 x 10 5 mM (0.1 ± 9.6) and one slide at 1.0 mM (1.6 ± 5.2). The average net nuclear grain count was below zero for all test material concentrations in Trial 2 with the exception of 0.1 mM where the average net nuclear grain count was 0.0 ± 2.9. The criterion for a positive response was an average net nuclear grain count of at least five in two experiments at any tested concentration. The results were thus negative. The number of cells in repair was not reported. The solvent and positive (DMBA) controls induced the appropriate responses. There was no evidence that unscheduled DNA synthesis, as determined by radioactive tracer procedures [nuclear silver grain counts] was induced. This study is classified as Acceptable/ Guideline. It satisfies the requirement for FIFRA Test Guideline; OPPTS 870.5550 [§ 84 2] for other genotoxic mutagenicity data. Compliance statements were not provided.

4.8 Neurotoxicity Adequacy of data base for Neurotoxicity: No neurotoxicity data are required.

870.6100 Delayed Neurotoxicity Study  Hen Study is not required of hexazinone, which is not an organophosphate.

870.6200 Acute Neurotoxicity Screening Battery HEXAZINONE/ 107201/ May/ 2002 TRED Toxicology Chapter 22 Study not required 870.6200 Subchronic Neurotoxicity Screening Battery Study not required.

870.6300 Developmental Neurotoxicity Study Study not required.

4.9 Metabolism Adequacy of data base for metabolism: The data base for metabolism is considered to be complete. No additional studies are required at this time.

870.7485 Metabolism  Rat EXECUTIVE SUMMARY: A metabolism study (MRID 00109237 & 00140162) was conducted to evaluate the absorption, distribution, metabolism, and excretion of hexazinone in male and female CD rats. Radiolabeled ( 14 C at position 2 or 4 on the cyclohexyl ring) hexazinone, (Lot # not reported, purity >95%, radiochemical purity >99%) was administered by gavage to groups of one male and one female rat at concentrations of 14 mg/ kg or 1000 mg/ kg. A third group of two male and two female rats received unlabeled hexazinone (~ 5 mg/ kg/ day) in the diet for three weeks before being given a single 14 mg/ kg radiolabeled gavage dose. Mass balance was excellent and ranged from 95 102% recovery for all treatment groups. Based on the amount of radiolabel recovered in the urine and cage wash, absorption of the test material was at least 83% with no dose or sex dependent differences noted. By 72 hours after treatment, essentially none of the radiolabeled test material was present in the tissues. Urine was the primary route of elimination accounting for ~83% of the administered dose. Urinary elimination was rapid and ~96% complete within 48 hours of treatment. No apparent sex or dose related differences were found. Fecal excretion was a minor route of elimination, accounting for ~16% of the dose and was rapid with ~95% occurring within 72 hours of treatment. Once again, no apparent sex or dose related differences were found. Essentially none of the parent compound was found in the urine (-83% of dose) or feces (-16% of dose) of male and female rats following multiple low dose or a single high dose treatment with hexazinone. (Molecular structures of the parent and metabolites can be found in Section IV, Appendix.) 3( 4 hydroxycyclohexyl) 6( dimethylamino) 1 methyl 1,3,5 triazine 2,4( 1H, 3H) dione (metabolite A) and 3( 4 hydroxycyclohexyl) 6( methylamino) 1 methyl 1,3,5 triazine 2,4( 1H, 3H) dione (metabolite C) comprised ~66 and 28%, respectively, of the identified fecal metabolites in males and females. These two metabolites resulted from hydroxylation of the cyclohexyl ring and differed only by the metabolic conversion of the 6 dimethyl amine to a secondary methyl amine. No sex, or HEXAZINONE/ 107201/ May/ 2002 TRED Toxicology Chapter 23 dose related differences in the formation and excretion of these metabolites were found. Three metabolites were identified in the urine of males and females (metabolite A and C, -57% and -28% of identified metabolites, respectively) . Two of the metabolites were identical to those found in the feces . The third metabolite (3( cyclohexyl) 6( methylamino) 1 methyl 1,3,5 triazine 2,4( 1H, 3H) dione) (metabolite B, -9% of urinary metabolites) resulted from demethylation of the 6 dimethyl amine group to form a secondary amine without hydroxylation of the 4 position on the cyclohexyl ring. Approximately 3% of the urine metabolites were unidentified polar compounds and 5% were isolated from the hydrolyzed urine, suggesting they had undergone glucuronide or sulfate conjugation. No differences between the sexes or dose groups in the metabolic conversion of hexazinone were found. This metabolism and disposition study with rats is considered Acceptable/ Nonguideline and does satisfy the requirements for a Metabolism and Pharmacokinetics Study [OPPTS 870.7485 (§ 85 1)]. Major deficiencies include the use of 1 2 male and female rats/ group; no submission of test material lot numbers, stability, or dose confirmation data; and study dates.

4.10 Special/ Other Studies None available.

5.0 TOXICITY ENDPOINT SELECTION 5.1 See Section 9.2 for Endpoint Selection Table.

5.2 Dermal Absorption No dermal absorption study is available. For dermal absorption, the NOAEL from the 21 day dermal toxicity study at the limit dose of 1000 mg/ kg/ day was considered a lower bound for the LOAEL, which was compared with LOAEL of 250 mg/ kg/ day from the range finding rabbit study (MRID# 00028863). The ratio of these two numbers was used to estimate a dermal absorption factor of 25%. The range finding study was chosen instead of the main rabbit developmental toxicity study (MRID# 00028863) for comparison because the main study was considered to be unacceptable for regulatory purposes.

Dermal Absorption Factor: 25 %

5.3 Classification of Carcinogenic Potential 5.3.1 Conclusions There was no evidence of treatment related tumors in chronic rat or mouse studies.

5.3.2 Classification of Carcinogenic Potential HEXAZINONE/ 107201/ May/ 2002 TRED Toxicology Chapter 24 The RfD/ Peer Review Committee has classified hexazinone as a group D chemical; no evidence of carcinogenicity in rats and in mice insufficient evidence of human carcinogenic potential.

5.3.3 Quantification of Carcinogenic Potential Not required.

6.0 FQPA CONSIDERATIONS 6.1 Special Sensitivity to Infants and Children There was no evidence of quantitative or qualitative postnatal susceptibility in a twogeneration study of reproduction. There was no quantitative or qualitative evidence of increased susceptibility following in utero exposure to rats or rabbits in developmental toxicity studies. However, the rabbit developmental toxicity study was unacceptable/ upgradable. Until another study is review, a 10X uncertainty factor for the data gap will remain. In rats, no developmental toxicity was seen at the highest dose level tested, and in rabbits, developmental effects were seen at a dose that was higher than that showing maternal toxicity.

6.2 Recommendation for a Developmental Neurotoxicity Study No neurotoxic potential was seen in any of the studies. A developmental neurotoxicity study is not required.

7.0 OTHER ISSUES None 8.0 REFERENCES:

MRID 00028863. Unknown (1980) Teratology Study in Rabbits. E. I. du Pont de Nemours and Company, Inc., Haskell Laboratory for Toxicology and Industrial Medicine, Newark, DE. Laboratory Project Id.: Haskell Laboratory Report No. 201 522, February 14, 1980. Unpublished.

MRID 00076956. McCooey, K. T., and Krahn, D. F. (1980). Chinese Hamster Ovary Cell Assay for Mutagenicity. E. I. du Pont de Nemours and Company, Haskell Laboratory for Toxicology and Industrial Medicine, Elkton Road, Newark, DE HEXAZINONE/ 107201/ May/ 2002 TRED Toxicology Chapter 25 19711. Haskell Laboratory Report No.: 56 81, MR No.: 0581 865, December 1, 1980. Unpublished.

MRID 00079203. Unknown (1981) Two Year Feeding Study in Mice. International Research and Development Corporation, Mattawan, MI. Laboratory Project Id.: HLO414 81, June 23, 1981. Unpublished.

MRID 00104977. Sherman, H. et. al. (1973) Ninety Day feeding Study in Rats with INA 3674. Haskell Laboratory. Laboratory Study Id.: 235 73, May 21, 1973. Unpublished.

MRID 00108638. Kaplan, A. M., Frazier, C. V., et al. (1977) Long Term Feeding Study in Rats with INA 3674. E. I. du Pont de Nemours and Company, Inc., Haskell Laboratory for Toxicology and Industrial Medicine, Newark, DE. Laboratory Project Id.: Haskell Laboratory Report No. 353 77, May 13, 1977. Unpublished MRID 00109237. Repisarda, C. (1982). Metabolism of 14 C labeled hexazinone in the rat. E. I. duPont de Nemours and Co., Biochemicals Dept., Research Div., Experimental Station, Wilmington, DE 19898. Document No. AMR 79 82. Unpublished.

MRID 00114484. Sherman, H. et al. (1973) Three Month Feeding Study in Dogs with INA3674 E. I. du Pont de Nemours and Company, Inc., Haskell Laboratory for Toxicology and Industrial Medicine, Newark, DE. Laboratory Project Id.: Haskell Laboratory Report No. 408 73, September 12, 1973. Unpublished.

MRID 00114486. Culik, R., et al. (1974) Teratogenic Study in Rats with INA 3674. E. I. du Pont de Nemours and Company, Inc., Haskell Laboratory for Toxicology and Industrial Medicine, Newark, DE. Laboratory Project Id.: Haskell Laboratory Report No. 265 74, April 9, 1974. Unpublished.

MRID 00130708. Summers, J. C. (1983) Unscheduled DNA Synthesis/ Rat Hepatocytes In Vitro. E. I. du Pont de Nemours and Co., Inc., Haskell Laboratory for Toxicology and Industrial Medicine, Elkton Road, P. O. Box 50, Newark, Delaware 19711. Laboratory Report No.: 766 82, MR No.: 4508 001, Date Issued: January 4, 1983. Unpublished.

MRID 00130709. Valachos, D., Irr, J. and Krahn, D. F.( 1982) In Vitro Assay for Chromosome Aberrations in Chinese Hamster Ovary (CHO) Cells. E. I. du Pont Nemours and Co., Inc., Haskell Laboratory for Toxicology and Industrial Medicine, HEXAZINONE/ 107201/ May/ 2002 TRED Toxicology Chapter 26 Elkton Road, P. O. Box 50, Newark, Delaware 19711. Laboratory Report No. 768 82, MR No. 4508 001, December 3, 1982. Unpublished.

MRID 00131355. Farrow, M. G., Cortina, T. and Zito, M. (1982). In Vivo Bone Marrow Cytogenetic Assay in Rats with H# 14,555: Final Report. Hazleton Laboratories America, Inc., 9200 Leesburg Turnpike, Vienna, Virginia 22180. HLA Project number: 201 573, December 9, 1982. Unpublished.

MRID 00140162. Rhodes, R. C., Jewell, R. A., Sherman, H. (No date). Metabolism of "Velpar" weed killer in the rat. E. I. duPont de Nemours and Co., Biochemicals Dept., Experimental Station and Haskell Laboratory for Toxicology and Industrial Medicine, Wilmington, DE 19898. No document or report number. Results published in J. Agric. and Food Chem., 28, 303 (1980)

MRID 40397501. Mullin, L. S. (1987) Teratogenicity Study of INA 3674 in Rats. E. I. du Pont de Nemours and Company, Inc., Haskell Laboratory for Toxicology and Industrial Medicine, Newark, DE. Laboratory Project Id.: Haskell Laboratory Report No. 748 86, January 30, 1987. Unpublished.

MRID 40826201. J. F. Russell Jr. and D. F. Krahn (1977). Mutagenicity Evaluation of Striazine 2,4( 1H, 3H) dione, 3 cyclohexyl 6 dimethylamino 1 methyl in Salmonella typhimurium. E. I. du Pont de Nemours and Company, Inc., Haskell Laboratory for Toxicology and Industrial Medicine, Elkton Road, P. O. Box 50, Newark, Delaware 19714. Haskell Laboratory Report No. 588 77, MR No. 0581 693; Date Issued: July 29, 1977. Unpublished.

MRID 41309005. Malek, D. (1989). Repeated Dose Dermal Toxicity: 21 Day Study with DPXA3674 207 (Hexazinone) in Rabbits. E. I. du Pont de Nemours and Company, Inc., Haskell Laboratory for Toxicology and Industrial Medicine, P. O. Box 50, Elkton Road, Newark, DE 19714. Study No. HLA 673 89. November 22, 1989. Unpublished.

MRID 41359301. Goldenthal, E. I. (1989) Supplement 1 to: Two Year Feeding Study in Mice with Hexazinone. International Research and Development Corporation, Mattawan, MI. Laboratory Project Id.: HLO 414 81, November 22, 1989. Unpublished.

MRID 42066501. Mebus, C. A. (1991). Reproductive and fertility effects with IN A3674 207; multigeneration reproduction study in rats. Haskell Laboratory, Newark, Delaware. Study No. HLA 404 91. September 11, 1991. Unpublished. HEXAZINONE/ 107201/ May/ 2002 TRED Toxicology Chapter 27 MRID 42162301. Dalgard, D. W. (1991) Chronic toxicology study in dogs with DPX A3674 207 (Hexazinone). Hazleton Washington, Inc., 9200 Leesburg Turnpike, Vienna, VA 22182. Laboratory Study No. 201 905. November 5, 1991. Unpublished.

MRID 42509301. Slone, Jr., T. W. (1992) Supplement 1 to: Two Year Feeding Study in Mice with Hexazinone. E. I. du Pont de Nemours and Company, Newark, DE. Laboratory Project Id.: HLO 414 81, October 2, 1992. Unpublished.

MRID 43202901. Slone, Jr., T. W., (1994) Supplement No. 3: Two Year Feeding Study in Mice with Hexazinone. E. I. du Pont de Nemours and Company, Newark, DE. Laboratory Project Id.: HLO 414 81, April 11, 1994. Unpublished.

MRID 45124401. Ford, L. S. (2000) Hexazinone 25L: Mouse Bone Marrow Micronucleus Assay. DuPont Pharmaceuticals Company, Safety Assessment Section, Stine Haskell Research Center, P. O. Box 30, Elkton Road, Newark, Delaware 19714 3507. Laboratory Project ID: DuPont 3852; Company Study Number: THA 00 02 47, April 12, 2000. Unpublished.

Other references:

U. S. EPA Report: Peer Review of Hexazinone (August 12, 1992).

U. S. EPA Report: RfD/ Peer Review Report of Hexazinone (March 24, 1993).

U. S. EPA Report: Carcinogenicity Peer Review of Hexazinone. (July 27, 1994).

U. S. EPA Report: Hexazinone 2 nd Report of the Hazard Identification Assessment Review Committee (TXR# 0050695).

U. S. EPA Report: HEXAZINONE  Report of the FQPA Safety Factor Committee (TXR# 0050750). HEXAZINONE/ 107201/ May/ 2002 TRED Toxicology Chapter 28 9.0 APPENDICES Tables for Use in Risk Assessment HEXAZINONE/ 107201/ May/ 2002 TRED Toxicology Chapter 29 9.1 Toxicity Profile Summary Tables 9.1.1 Acute Toxicity Table Acute Toxicity Data on FENBUTATIN OXIDE Guideline No./ Study Type MRID No. Results Toxicity Category 870.1100 Acute oral toxicity 41235004 LD50 = 1200 mg/ kg III 870.1200 Acute dermal toxicity 00104974 LD50 > 5278 mg/ kg IV 870.1300 Acute inhalation toxicity 41756701 (1991) LC50 > 3.94 mg/ L( 4 hour) III 870.2400 Acute eye irritation 00106003 Irreversible corneal opacity I 870.2500 Acute dermal irritation 00106004 Mild IV 870.2600 Skin sensitization 41235005 Not a dermal sensitizer in the Buehler test in Guinea pigs NA 9.1.2 Subchronic, Chronic and Other Toxicity Tables Guideline No./ Study Type MRID No. (year)/ Classification /Doses Results 870.3100 90 Day oral toxicity rats 0010977 (1973) Dose: 0, 200, 1000, 5000 ppm (equivalent to 0, 16.0/ 16.4, 81.0/ 87.3, 440/ 451 mg/ kg/ day, male/ female) Acceptable NOAEL = 1000 ppm (81.0/ 87.3 mg/ kg/ day male/ female) LOAEL = 5000 ppm (440/ 451 mg/ kg/ day male/ female) based decreased body weight and food efficiency.

870.3150 90 Day oral toxicity in non rodents 00114484 (1973) Doses of 0, 200, 1000, or 5000 ppm (equivalent to 0/ 0, 5.1/ 7.0, 25.9/ 31.6, 122.5/ 137.3 mg/ kg/ day, males/ females)

Acceptable NOAEL = 1000 ppm (equivalent to 25.9/ 31.6 mg/ kg/ day for males/ females). LOAEL = 5000 ppm (equivalent to 122.5/ 137.3 mg/ kg/ day in males/ females) based on decreased body weight gains, increased relative liver weights, and increased alkaline phosphatase levels in both sexes and transiently decreased food consumption in the females. HEXAZINONE/ 107201/ May/ 2002 TRED Toxicology Chapter Guideline No./ Study Type MRID No. (year)/ Classification /Doses Results 30 870.3200 21/ 28 Day dermal toxicity in rabbits 41309005 (1989) Doses: 0, 50, 400, or 1000 mg/ kg/ day Acceptable NOAEL = 1000 mg/ kg/ day. LOAEL = was not identified for systemic and dermal toxicity.

870.3250 90 Day dermal toxicity Not required 870.3465 90 Day inhalation toxicity The 90 day inhalation study is not required, however a 28 Day inhalation study is required (contact Agency prior to conducting study)

870.3700a Prenatal developmental in rats 40397501 (1980) Doses: 0, 40, 100, 400, or 900 mg/ kg Acceptable Maternal NOAEL = 100 mg/ kg/ day LOAEL = 400 mg/ kg/ day based on decreased food consumption during dosing and nominal decreases in body weight gain from day 7 to day 17 and at all measured intervals between and at 900 mg/ kg/ day on mortality and decreased body weight gains and food consumption. Developmental NOAEL = 400 mg/ kg/ day LOAEL = 900 mg/ kg/ day based on decreased female fetal weight, and increased incidence of kidneys with no papilla (malformation), and an increased incidence of misaligned sternebrae (variation).

870.3700a Prenatal developmental in rats 00114486 (1974) Doses: 0, 200, 1000, or 5000 ppm (equivalent to 0, 18.9, 94.5, and 482.0 mg/ kg) Unacceptable/ Upgradable Maternal: NOAEL is 1000 ppm (equivalent to 94.5 mg/ kg/ day). LOAEL = 5000 ppm (equivalent to 482 mg/ kg/ day) based on decreased body weights, body weight gains, and food efficiency. Developmental: NOAEL = 5000 ppm (equivalent to 482.0 mg/ kg/ day). LOAEL was not observed. HEXAZINONE/ 107201/ May/ 2002 TRED Toxicology Chapter Guideline No./ Study Type MRID No. (year)/ Classification /Doses Results 31 870.3700b Prenatal developmental in rabbits 00028863 (1980) Doses: 0, 20, 50, or 125 mg/ kg Unacceptable/ Upgradable Maternal NOAEL = 50 mg/ kg/ day LOAEL = 125 mg/ kg/ day based on transient decreases in food consumption and body weight gains. Developmental NOAEL = 50 mg/ kg/ day LOAEL = 125 mg/ kg/ day based on possible skeletal abnormalities and total abnormalies.

870.3800 Reproduction and fertility effects in rats 42066501 (1991) Acceptable 0, 200, 2000 or 5000 ppm M: 0, 11.8, 117 or 294 mg/ kg/ day F: 0, 14.3, 143 or 383 mg/ kg/ day Parental/ Systemic NOAEL = 14.3 mg/ kg/ day LOAEL = 143 mg/ kg/ day based on male body weight decrement. Reproductive NOAEL = 383 mg/ kg/ day LOAEL = None based on no effects on or organs of reproduction. Offspring NOAEL = 14.3 mg/ kg/ day LOAEL = 143 mg/ kg/ day based on reduced female pup weight at birth and during lactation.

870.4100a Chronic toxicity in rats See 870.4300 NOAEL = LOAEL =

870.4100b Chronic toxicity dogs 42162301 (1991) Doses: 0, 200, 1500, or 6000 ppm (equivalent to 5.00/ 4.97, 41.24/ 37.6 and 161/ 167 mg/ kg/ day, male/ female.

Acceptable NOAEL = 200 ppm (5.0/ 5.0 mg/ kg/ day, male/ female) LOAEL = 1500 ppm (41.2 and 37.57 mg/ kg/ day, respectively) based on thinness in one male and hepatotoxicity as evidenced by changes in clinical chemistry parameters and microscopic lesions.

870.4200 Carcinogenicity rats See below 870.4300 No evidence of carcinogenicity HEXAZINONE/ 107201/ May/ 2002 TRED Toxicology Chapter Guideline No./ Study Type MRID No. (year)/ Classification /Doses Results 32 870.4200 Carcinogenicity mice 00079203 (1981), 41359301 (1989), 42509301 (1992) and 43202901 (1994) Doses: 0, 0, 200, 2500 or 10,000 ppm (equivalent to 28/ 34, 366/ 450 and 1635/ 1915 mg/ kg/ day, male/ female)

Acceptable NOAEL = 200/ 2500 ppm (28/ 450 mg/ kg/ day, male/ female, respectively) LOAEL = 2500 ppm for males (equivalent to 366 mg/ kg/ day) based on gross liver nodules/ masses, hyperplastic nodules in the liver and centrilobular hepatocyte hypertrophy and 10,000 ppm for females (equivalent to 1915 mg/ kg/ day [limit dose]) based on decreased body weights, increased relative liver/ gall bladder weights, hyperplastic nodules and centrilobular hepatocyte hypertrophy. Insufficient evidence for carcinogenicity.

870.4300 Combined chronic/ carcinogenicity/ rats 00108638 (1977) Doses: 0, 200, 1000, or 2500 ppm (equivalent to 0, 10.2/ 12.5, 53.4/ 67.5, or 138/ 179 mg/ kg/ day, male/ female)

Acceptable NOAEL = 200 ppm for males and females (10.2/ 12.5 mg/ kg/ day, male/ female). LOAEL = 1000 ppm for males and females (equivalent to 53.3/ 67.5 mg/ kg/ day, male/ female) based on decreased body weight and food efficiency in males and females. In males at 2500 ppm the body weight decrement and food efficiency decrement occurred only for the first 6 months of the study. The carcinogenic potential of hexazinone is considered negative.

Gene mutation 870.5100; Reverse mutation in Salmonella strains 40826201 (1977) 200, 400, 600, 800 and 1000 :g/ plate S9 and 400, 800, 1200, 1600 and 2000 :g/ mL + S9 mix.

Unacceptable No mutagenic potential was seen, but doses insufficent to cause cell toxicity.

Gene mutation 870.5300; hamster CHO cells/ HPRT assay 00076956 (1980) Trial 1 were 2.0, 11.1, 13.1, 13.9 and 14.3 mM S9 and 2.0, 7.9, 8.9, 9.3 and 9.9 mM +S9. Trial 2 were 2.0, 5.9, 11.1, 13.1 and 13.9 mM S9 and 2.0, 7.9, 8.9, 9.3 and 9.9 mM + S9. Acceptable No evidence of mutagenic potential at cytotoxic doses. HEXAZINONE/ 107201/ May/ 2002 TRED Toxicology Chapter Guideline No./ Study Type MRID No. (year)/ Classification /Doses Results 33 Cytogenics 870.5375; Chromosomal aberrations in hamster CHO cells 00130709 (1982) In Trial 1, 1.58, 3.94, 15.85 and 19.82 mM S9 and 0.32, 3.17, 7.93 and 15.85 mM + S9. In Trial 2, 1.58, 3.94, 7.93 and 15.85 S9 0.32, 3.17, 7.93 and 15.85 mM + S9 Acceptable Positive for structural chromosomal aberrations with and without S9.

Other Effects 870.5385, In vivo Rat bone marrow cytogenics assay 00131355 (1982) Rat doses: 100, 300 or 1000 mg/ kg Unacceptable No evidence of mutagenic potential, but insufficient animals and cells were tested.

Other Effects 870.5395 Mouse bone marrow micronucleus test 45124401 (2000) Mouse doses: 1000, 2000 and 3000 mg/ kg Acceptable No evidence of clastogenic or aneugenic effect in bone marrow at toxic doses..

Other Effects 870.5550, UDS in rat hepatocytes 00130708 (1983) Trial 1: 1 x 10 5 , 1 x 10 4 , 1 x 10 3 , 1 x 10 2 , 0.1, 1.0, 10.0 and 30.0 mM and Trial 2: 1 x 10 5 , 1 x 10 4 , 1 x 10 3 , 1 x 10 2 , 0.1, 1.0, 5.0, 10.0 and 30.0 mM. Acceptable No evidence of mutagenic potential at precipitating dose levels.

870.6200a Acute neurotoxicity screening battery Not required 870.6200b Subchronic neurotoxicity screening battery Not required 870.6300 Developmental neurotoxicity Not required  HEXAZINONE/ 107201/ May/ 2002 TRED Toxicology Chapter Guideline No./ Study Type MRID No. (year)/ Classification /Doses Results 34 870.7485 Metabolism and pharmacokinetics 00140162 & 00109237 (1980 &1982) Acceptable No parent was seen in urine or feces, which was rapidly absorbed and excreted. Two identified metabolites resulted from hydroxylation of the cyclohexyl ring and differed only by the metabolic conversion of the 6 dimethyl amine to a secondary methyl amine. No sex, or doserelated differences in the formation and excretion of these metabolites were found.

870.7600 Dermal penetration Not required Special studies None submitted 9.2 Summary of Toxicological Dose and Endpoints for HEXAZINONE for Use in Human Risk Assessment Exposure Scenario Dose (mg/ kg/ day) UF /MOE Hazard Based Special FQPA Safety Factor Endpoint for Risk Assessment Dietary Risk Assessments Acute Dietary females 13 50 years of age NOAEL = 400 UF = 1000 Acute RfD = 0.40 mg/ kg/ day 1x Developmental Toxicity  Rat LOAEL is 900 mg/ kg/ day based on decreased male and female fetal weight, kidneys with no papilla (malformation) and misaligned sternebrae (variation)

Acute Dietary general population including infants and children An appropriate endpoint attributable to a single dose was not identified in the oral studies, including the rat and rabbit developmental studies.

Chronic Dietary all populations NOAEL= 5.0 UF = 100 Chronic RfD = 0.05 mg/ kg/ day 1x Chronic one year feeding  Dog LOAEL = 41.24 male; 37.57 female mg/ kg/ day based on severe body weight decrement and clinical chemistry changes including elevated aspartate aminotransferase and alkaline phosphatase. HEXAZINONE/ 107201/ May/ 2002 TRED Toxicology Chapter Exposure Scenario Dose (mg/ kg/ day) UF /MOE Hazard Based Special FQPA Safety Factor Endpoint for Risk Assessment 35 Incidental Oral Short Term (1  30 Days) Residential Only There are no residential uses at the present time and therefore, endpoints were not selected.

Incidental Oral Intermediate Term (1  6 Months) Residential Only There are no residential uses at the present time and therefore, endpoints were not selected.

Non Dietary Risk Assessments Dermal Short Term (1  30 days) No hazard was identified, therefore quantification of risk is not required. No systemic toxicity was seen at the limit dose following repeat dermal application, and there were no concerns for developmental or reproductive toxicity.

Residential Occupational Dermal Intermediate Term 1 (1  6 Months) Oral NOAEL= 5.0 mg/ kg/ day Chronic one year feeding  Dog LOAEL = 41.24 male; 37.57 female mg/ kg/ day based on severe body weight decrement and clinical chemistry changes including elevated aspartate aminotransferase and alkaline phosphatase. Residential MOE= N/ A N/ A Occupational MOE= 100 N/ A Dermal Long Term 1 (1  6 Months) Oral NOAEL= 5.0 mg/ kg/ day Chronic one year feeding  Dog LOAEL = 41.24 male; 37.57 female mg/ kg/ day based on severe body weight decrement and clinical chemistry changes including elevated aspartate aminotransferase and alkaline phosphatase. Residential MOE= N/ A N/ A Occupational MOE= 100 N/ A Inhalation Short Term 2 (1  30 days) Oral NOAEL= 100 mg/ kg/ day Developmental Toxicity  Rat LOAEL = 400 mg/ kg/ day based on decreases in maternal food consumption and dose related body weight decrement. Residential MOE= N/ A N/ A Occupational MOE= 100 N/ A HEXAZINONE/ 107201/ May/ 2002 TRED Toxicology Chapter Exposure Scenario Dose (mg/ kg/ day) UF /MOE Hazard Based Special FQPA Safety Factor Endpoint for Risk Assessment 36 Inhalation Intermediate Term (1  6 Months) Oral NOAEL= 5.0 mg/ kg/ day Chronic one year feeding  Dog LOAEL = 41.24 male; 37.57 female mg/ kg/ day based on severe body weight decrement and clinical chemistry changes including elevated aspartate aminotransferase and alkaline phosphatase. Residential MOE = N/ A N/ A Occupational MOE= 100 N/ A Inhalation Long Term (> 6 Months) Oral NOAEL= 5.0 mg/ kg/ day Chronic one year feeding  Dog LOAEL = 41.24 male; 37.57 female mg/ kg/ day based on severe body weight decrement and clinical chemistry changes including elevated aspartate aminotransferase and alkaline phosphatase. Residential MOE= N/ A N/ A Occupational MOE= 100 N/ A Cancer Classification: D  Not Classifiable as to human carcinogenicity 1 Since an oral NOAEL was selected 25% dermal absorption factor should be used for route to route exposures. 2 Absorption via the inhalation route is assumed to be equivalent to oral absorption. N/ A = Not Applicable; there are no residential uses.


March 4, 2010

MEMORANDUM

TO:  		Docket EPA-HQ-OAR-2009-0472

SUBJECT:	Economy-Wide Impacts of Greenhouse Gas Tailpipe Standards

EPA has undertaken an analysis of the economy-wide impacts of the
greenhouse gas emissions (GHG) tailpipe standards as an exploratory
exercise that EPA believes could provide additional insights into the
potential impacts of the rule.  This analysis updates the work done for
the rule to reflect the final rulemaking estimates of vehicle costs,
fuel savings, and world oil prices.  The results presented in this memo
were not a factor regarding the appropriateness of the GHG tailpipe
standards.  It is important to note that the results of this modeling
exercise are dependent on the assumptions associated with how consumers
will respond to increases in higher vehicle costs and improved vehicle
fuel economy as a result of the rule.  Please see Preamble Section III.H
of the rule for a discussion of the underlying distinctions and
implications.

It is anticipated that the GHG tailpipe standards would have impacts on
the U.S. economy that extend beyond the transportation sector.  The
price of light-duty vehicles would increase with this rule.  This rule
would also lower the demand for transportation fuels, resulting in fuel
savings to vehicle users and a lower overall world oil price. This
combination of effects—price increases for vehicles and lower demand
and world oil prices—would impact all sectors of the economy that use
light-duty vehicles and fuels as intermediate inputs (e.g., delivery
vehicles) to produce final goods.  Households would also be impacted
indirectly as consumers of final goods, and directly as consumers of
fuels and light-duty vehicles.

It is important to note, however, that these potential impacts do not
represent additional benefits or costs from the regulation.  Instead,
they represent the effects on the U.S. economy as its direct benefits
and costs are transmitted through changes in prices in the affected
markets, including those for vehicles and their components, fuel, and
the various resources used to supply them.

To estimate the impacts of this rule on U.S. Gross Domestic Product
(GDP) and personal consumption, EPA has used an economy-wide, computable
general equilibrium (CGE) model.  The economy-wide model used in this
analysis is the Intertemporal General Equilibrium Model (IGEM).  IGEM is
a model of the U.S. economy with an emphasis on the economy’s energy
and environmental aspects.  IGEM is a dynamic model which depicts growth
of the economy due to capital accumulation, technical change and
population change.  The model utilizes a unified accounting framework
consistent with the National Income and Product Accounts and the
Industry Classification System.  It is a detailed multi-sector model
covering thirty-five industries, consisting of five energy and thirty
non-energy sectors.  The model ensures market balances (supply equals
demand) in value and quantity terms, including limits placed on private
investment dictated by domestic and foreign saving behavior and by the
fiscal policies of federal, state and local governments.  Capital
accumulation in the model arises from the saving and investment behavior
of households and businesses and provides an essential input to
production and consumption.  Households in the model make choices
regarding present and future consumption (i.e., saving) and make choices
regarding the allocation of time between labor and leisure.  The model
covers all aspects of long-run growth including the supply of capital,
labor, imported and intermediate inputs to production; the rates and
directions of exogenous and endogenous technical change for each
producing sector; and the degrees of substitutability among inputs and
commodities in production and final demand (consumption, investment,
governments and foreign trade).  The substitution possibilities for both
producers and consumers in IGEM are driven by model parameters that are
based on observed market behavior revealed over the past forty to fifty
years.

In order to model this rule, the CGE model uses outputs of the
transportation sector models as inputs to determine the economy-wide
impacts of this rule.  Specifically, the model uses information from
other models on incremental costs of vehicle technologies, reduction in
fuel consumption, and impacts on the world oil price.  The incremental
cost of vehicle technologies is used to generate a percentage change in
vehicle cost that is applied to the IGEM motor vehicles sector.  Since
cars and light duty trucks make up approximately 50% of the motor
vehicles sector, the cost increases represented here only apply to that
portion of the IGEM sector.  The data on reduction in fuel consumption
are used as inputs to IGEM in order to reduce the amount of refined
petroleum sector output required by the transportation sector and other
sectors in the model.  Finally, the estimates of reductions in the world
oil price are directly used to reduce the oil price in the model.  The
changes in world oil price are estimated using the Energy Security Oil
Premium Model maintained by Oak Ridge National Laboratory, which is
discussed in more detail in Chapter 4 of the Technical Support Document
(TSD).

Impacts on U.S. GDP

In order to use IGEM to estimate the real U.S. GDP impacts of this rule,
we analyzed the impact of changes in the costs of light-duty vehicles,
changes in fuel consumption from the shift to a lower GHG-emitting
vehicle stock, and the impacts of changes in the demand for motor fuels
on fuel prices.  See the Regulatory Impact Analysis (RIA) Chapter 4 for
additional information on the change in vehicle technology costs, RIA
Chapter 6.3 for details on changes in fuel demand, and RIA Chapter 8.2
for a discussion on the monopsony effect.  It is important to note that
the economy-wide analysis does not include a representation of a number
of additional benefits (e.g. reducing greenhouse gas and non-GHG
emissions, reducing refueling time), and thus the GDP impacts presented
here do not incorporate the results of a complete cost benefit analysis.
 Table 1 and Figure 1 show the Reference Case GDP and GDP with this rule
from 2012 through 2050.

Table 1 Annual GDP Impacts Associated with This Rule (Billions of 2007
dollars)

year	reference case gdp	gdp with RULE	% change from reference case

2012	$15,582	$15,610	0.18%

2016	$17,214	$17,254	0.23%

2020	$18,920	$19,005	0.45%

2030	$24,315	$24,503	0.77%

2040	$30,459	$30,718	0.85%

2050	$37,904	$38,244	0.90%

Figure   SEQ Figure \* ARABIC  1  Gross Domestic Product

In the Reference Case, GDP rises from approximately $15.6 trillion in
2012 to $17.2 trillion in 2016, $18.9 trillion in 2020, $24.3 trillion
in 2030, $30.5 trillion in 2040, and $37.9 trillion in 2050.  With this
rule, GDP rises from approximately $15.6 trillion in 2012, to $17.3
trillion in 2016, $19.0 trillion in 2020, $24.5 trillion in 2030, $30.7
trillion in 2040, and $38.2 trillion in 2050.

The fuel savings and lower world oil prices that result from this rule
lead to lower prices economy-wide, even when the impact of higher
vehicle costs are factored into this analysis.  Lower prices allow for
additional purchases of investment goods which, in turn, lead to a
larger capital stock.  These price reductions also allow higher levels
of real government spending while improving U.S. competitiveness thus
promoting increased exports relative to the growth driven increase in
imports.  As a result, GDP is expected to increase as a result of this
rule.

Impacts on U.S. Consumption

In addition to showing the impacts of the GHG vehicle rule on U.S. GDP,
EPA also shows the impacts on real U.S. personal consumption
expenditures.  Table 2 and Figure 2 show the Reference Case consumption
and consumption with this rule from 2012 through 2050.

Table 2 Consumption Impacts of the Rule (Billions of 2007 dollars)

year	reference case consumption	consumption with RULE	% change from
reference case

2012	$9,559	$9,559	-0.01%

2016	$10,669	$10,687	0.18%

2020	$11,764	$11,806	0.36%

2030	$14,945	$15,083	0.92%

2040	$18,804	$19,040	1.26%

2050	$23,165	$23,505	1.47%

Figure   SEQ Figure \* ARABIC  2  Consumption

In the Reference Case, consumption rises from approximately $9.6
trillion in 2012 to $10.7 trillion in 2016, $11.8 trillion in 2020,
$14.9 trillion in 2030, $18.8 trillion in 2040, and $23.2 trillion in
2050.  With this rule, consumption rises from approximately $9.6
trillion in 2012 to $10.7 trillion in 2016, $11.8 trillion in 2020,
$15.1 trillion in 2030, $19.0 trillion in 2040, and $23.5 trillion in
2050.  The consumption impacts on a per household basis are presented in
Table 3 and Figure 3  REF _Ref238028495 \h   .

Higher vehicle costs are projected to reduce household consumption
slightly in the first few years of the rule implementation.  Over time,
fuel savings increase and the price of world oil decreases, which leads
to lower prices economy-wide.  As a result, household consumption
increases over the long term.

Table 3 Consumption Impacts of This Rule per Household (2007$)

year	reference case consumption	consumption with RULE	change from
reference case

2012	$77,251	$77,246	-0.01%

2016	$82,016	$82,161	0.18%

2020	$86,174	$86,483	0.36%

2030	$98,140	$99,046	0.92%

2040	$112,607	$114,024	1.26%

2050	$127,556	$129,426	1.47%

Figure   SEQ Figure \* ARABIC  3  Consumption per Household

See the attached spreadsheet for additional information.

 The model is developed and run by Dale W. Jorgenson Associates for EPA.
  Model Homepage:

  HYPERLINK "http://www.dja.insightworks.com/"
http://www.dja.insightworks.com/

 For the economy-wide analysis, the change in fuel consumption projected
in Section 6 was modeled relative to the AEO 2009 baseline projections.
Thus, the Reference Case used in the economy-wide analysis differs from
the baseline used in other sections of this rule.