Interregional Research Project No. 4 (IR

- 4)

PP# 3E8211

EPA has received a pesticide petition ( 3E8211 ) from IR

- 4
, Rutgers, The State University of New Jersey, 500 College Road East, Suite 201W, Princeton, NJ 08540 proposing, pursuant to section 408(d) of the Federal Food, Drug, and Cosmetic Act (FFDCA), 21 U.S.C. 346a(d), to amend 40 CFR part 180

, by establishing a tolerance for residues of

m etrafenone , (3

- bromo

- 6

- methoxy

- 2

- methylphenyl)(2, 3,4

- trimethoxy

- 6

- methylphenyl) methanone] in or on the raw agricultural commodity a pricot at 0 .7 part s per million (ppm) ; c herry, subgroup 1 2

- 12A at 2.0 ppm ; f ruit, small, vine climbing, except fuzzy kiwifruit, subgroup 13

- 07F at 4

. 5 ppm ; h op , dried cones at 70 .0 ppm ; p each, subgroup 12

- 12 B at 0 .7 ppm ; and v egetable, cucurbit, group 9 at 0 .5 ppm. IR

- 4 also propose d , upon the approval of the aforementioned tolerances, to remove established tolerance for grapes

. EPA has determined that the petition contains data or information regarding the elements set forth in section 408 (d)(2) of FDDCA; however, EPA has not fully evaluated the sufficiency of the submitted data at this time or whether the data supports granting of the petition. Additional data may be needed befo re EPA rules on the petition.

A. Residue Chemistry

1. Plant metabolism. In plant metabolism studies conducted i n grape vine s, cucumber
, and wheat with metrafenone
, the parent compound was the principal residue in almost all
matrices

. M etrafenone is metabolized through methyl and ring oxidative bio

- transformations, followed by enzymatic glucoside conjugation reactions to yield the conjugates from their corresponding aglycons. All major metabolites, which were present at very low levels, are
consi dered non

- relevant as all were detected in the rat metabolism study as aglycons or conjugates, and can therefore be considered as not toxicologically significant. Thus, only parent metrafenone is considered relevant to define the residue in plants.

2. A nalytical method. The residues o f parent metrafenone in /on Cherry, Hops, Peach,
C ucu mber, Cantaloupe , and Squash RAC samples were quantitated using an LC/MS/MS
multi

- residue QuEChERS method (BASF Study No. 398340)

. The method was successfully

validated on all the relevant commodities in conjunction with these studies prior to analysis of the field samples. Acceptable concurrent method recovery data for all the RAC samples
were also obtained for metrafenone. The va lidated limit of quantitation (LOQ) for residues
of metrafenone in/on all the commodities was 0.01 ppm. The method li mit of detection (LOD) was 0.001 ppm, or approximately 1 0% of the LOQ. An independent laboratory validation demonstrated good performance of the QuEChERS method.

3. Magnitude of residues. IR

- 4 has submitted field trial data for metrafenone (BAS

560 F ) on cherry, hops, peach, cucumber, cantaloupe, and squash

. The number and
locations of field trials are in accordance with OPPTS Guideline 860.1500. Field trials were carried out using the maximum label rates, the maximum number of applications, and the minimum pre

- harvest interval (PHI) for all the crops.

B. Toxicological Profile2

1. Acute toxicity. In an acute toxicity study with rats, metrafenone was practically

non
- toxic (EPA Tox. Category IV). In an acute neurotoxicity study with rats, no signs of neurotoxicity were detected up to 2,000 mg/kg b.w., the highest dose tested.

2. Genotoxicty. M etrafenone was evaluated for its potential genotoxicity in vitro using bacterial and mammalian cell mutagenicity tests and a chromosome damage (clastogenicity) test. The results of these studies demonstrated the absence of a genotoxic
effect. In vivo , the test substance was assessed for the induction of micronuclei in mice. The result of this study showed that metrafenone has no chromosome

- damaging potential.

It is therefore concluded, that metrafenone has no mutagenic or genotoxic properties both

in vitro and in vivo

.

3. Reproductive and developmental toxicity. The reproductive and developmental toxicity of metrafenone was investigated in a 2

- generation reproduction study in rats as well as in prenatal toxicity studies in rats and rabbits.

In the definitive 2

- generation reproduction study in rats, the NOAEL for fertility and reproduction was 10,000 ppm (the highest concentration tested), equivalent to approximately 811 mg/kg b.w./day based on food consumption data during the premating periods. The parental NOAEL of metrafenone is 500 ppm (approximately 39 mg/kg b.w./day based on food consumption data). The 1,000 ppm treatment showed statistically significant decreases in body weight and weight gain in F1 parental males and increased

absolute and re lative liver weights in females. The NOAEL for pup (offspring) toxicity was 1,000 ppm (approximately 79 mg/kg b.w./day based on food consumption data); the 10,000 ppm treatment showed a statistically significant decrease in pup body weight (31%) during

la ctation, an increase in relative liver weights at weaning, and a delay in vaginal opening (F1 only).

In the prenatal toxicity study in rats, there was no treatment

- related maternal or developmental toxicity observed, even at the highest dose tested (1,000 mg/kg b.w./day). On the basis of these data, the maternal NOAEL of metrafenone is 1,000 mg/kg b.w./day (highest dose tested). The 1,000 mg/kg b.w./day dose showed a statistically significantly increased ratio of liver weight to terminal body weights. Ho wever, no correlating microscopic changes were diagnosed, indicating that the increased relative liver weight was not considered toxicologically significant. The developmental NOAEL for metrafenone is 1,000 mg/kg b.w./day (no effects were observed at the highest dose tested). Based on the above results, metrafenone is not selectively toxic to the fetus. In addition, metrafenone was not teratogenic in rats.

In the rabbit prenatal toxicity study, developmental toxicity was observed in the presence
of maternal toxicity. Specifically, the maternal NOAEL is 50 mg/kg b.w./day based on the following: reduced body weight gains and reduced feed consumption (absolute and relative) at both 350 and 700 mg/kg b.w./day. In addition, at these two dose levels, a do se
related, statistically significant increase in absolute and relative (to body weight) liver weights occurred, as compared to controls. Also, increased incidences and/or severities of3

periportal hepatocellular hypertrophy and diffuse and/or periportal h epatocellular vacuolation were observed at 350 and 700 mg/kg b.w./day. In this prenatal toxicity study in rabbits, the developmental NOAEL of metrafenone is 350 mg/kg b.w./day, as based on the slight but statistically significant reduction in fetal body w eights at 700 mg/kg b.w./day. Therefore, because developmental toxicity was only observed at dose levels that were maternally toxic, metrafenone is not selectively toxic to the fetus. In addition, metrafenone was not teratogenic in rabbits.

Overall, for the reproductive and developmental toxicity studies, the lowest NOAEL for maternal/parental toxicity was 39 mg/kg b.w./day (two

- generation reproduction study) and for pup toxicity was 79 mg/kg b.w./day (two

- generation reproduction study).

4. Subchronic toxicity. The subchronic toxicity of metrafenone was investigated in a dietary 28

- day study in rats, a 28

- day oral toxicity study in dogs, and 3

- month toxicity studies in rats, mice, and dogs. In addition, a 28

- day neurotoxicity study as well as a 28

- day immunotoxicity study
, were conducted with rats

.

The signs of toxicity observed in the three species tested were overall similar and consisted of reduced body weight gain at the highest tested dose levels. The observed effects on clinical chemistry in r ats and mice can be linked to the microscopic effects observed in the liver. The effects observed typically included increased cholesterol, total protein, and total bilirubin (mice only). Organ weights and/or pathology indicated the liver to be the only consistent target organ in all three species tested. The changes included, periportal cytoplasmic vacuolation in rats, centrilobular hepatocellular hypertrophy in mice, and increased liver weights in rats, mice, and dogs.

In the 28

- day neurotoxicity study with rats, there was no evidence of neurotoxicity in all treatment groups, with a No

- Observed

- Adverse

- Effect Level (NOAEL) for neurotoxicity of 15,000 in the diet (equivalent to 1,371 mg/kg b.w./day for both sexes , as base d on food consumption data , which exceeds a limit dose of 1,000 mg/kg b.w./day ). These results, coupled with the lack of neurotoxic effects observed in acute, sub

- chronic and chronic studies with other species, indicate that metrafenone is not potentially neurotoxic.

In the 28

- day immuno toxicity study with female rats , there was no evidence of
immuno toxicity in all treatment groups, with a No

- Observed

- Adverse

- Effect Level (NOAEL) for immuno toxicity of 12 ,000 in the diet (equivalent to 1, 086 mg/kg b.w./d ay , as based on food consumption data , which exceeds a limit dose of 1,000 mg/kg b.w./day ).

These res ults, coupled with the lack of immuno toxic effects observed in acute, sub

- chronic and chronic studies with other species, indicate that metrafenone is not potentially
immuno toxic.

5. Chronic toxicity. The chronic toxicity of metrafenone was evaluated in a 1

- year oral administration study in dogs, a 24

- month feeding study with rats and an 18

- month feeding study with mice.

Administration of metrafenone to dogs for one year resulted in mild increases in mean alkaline phosphatase in males after 9 and 12 months of dosing at 500 mg/kg b.w./day4

(highest dose tested). Mean absolute and relative liver weights were both statistically significantly increased in females at 500 mg/kg b.w./day and relative liver weights were statistically significantly increased in males at 500 mg/kg b.w./day. However, there were no associated macroscopic or microscopic findings in the livers of these animals. Therefore, the slig ht but statistically significant differences in liver weights and alkaline phosphatase (in males) were not considered to be of toxicological significance. All other parameters evaluated including mortality, clinical observations, body weights and food con sumption data, ophthalmology, hematology, coagulation and urinalysis data, and macroscopic and microscopic examinations revealed no adverse effects due to administration of
metrafenone . Therefore, the NOAEL for oral administration of metrafenone to pure

- b red Beagle Dogs was 500 mg/kg b.w./day, the highest dose tested.

Treatment of Sprague

- Dawley rats with metrafenone for 24 months resulted in markedly reduced body weight gains in females at 5,000 (26%) and 20,000/10,000 ppm (42%) and a

lesser reduction in body weight gain for males at 20,000 ppm (14%). Microscopic effects in the liver and kidney were associated with clinical chemistry changes in males and females at doses of 5,000 ppm and greater. Slight anemia was observed in females at 5,000 ppm

and hi gher, which was reversed at 24 months. An increase in the incidence of hepatocellular necrosis after 12 months and benign hepatocellular adenomas was observed in females at 5,000 ppm and greater which are dietary concentrations that exceeded the

MTD. The refore, the NOAEL for systemic toxicity and for oncogenic effects following dietary administration of metrafenone to Sprague

- Dawley rats for 24 months, was 500 ppm (25 mg/kg b.w./day as based on food consumption data).

Treatment of albino mice with metraf enone for 18 months resulted in statistically significant increases in the following: liver weights (absolute and relative, in females), hepatocellular hypertrophy in males, renal chronic nephropathy in males and extramedullary hematopoiesis in the spleen of females at 1,000 ppm, the next highest concentration tested. Therefore, the NOAEL for systemic toxicity following dietary
administration of metrafenone to albino mice for 18 months, was 250 ppm (46 mg/kg b.w./day as based on food consumption data).

A statistically significant (P<0.01) increase in the incidence of hepatocellular neoplasms (adenomas and carcinomas) was observed in the livers of male mice receiving 7,000 ppm (19/66, 28.8%), as compared to controls (6/65, 9.2%). There was also a marginal increase in the incidence of hepatocellular neoplasms in females receiving 7,000 ppm (4/65), as compared to the control mice (2/65). The incidence of 14/66 (21.2%) hepatocellular adenoma for males at 7,000 ppm is slightly above the maximum range of histori cal control data at the testing laboratory (14.8%) and at Charles River Laboratories (19.2%). The incidence of 5/66 (7.6%) hepatocellular carcinoma in males at 7,000 ppm is within the maximum range of historical control data at both the testing facility ( 9.2%) and Charles River Laboratories (11.5%). Although the number of hepatocellular neoplasms in males receiving 1,000 ppm was also slightly increased (9/65, 13.8%) compared to the untreated controls (6/65, 9.2%), this slight increase was not statisticall y significant (p<0.05) and was within the range of the historical controls (9.2

- 18.5%) at the testing laboratory. The slight increase in hepatocellular neoplasms in male mice at 1,000 ppm may have resulted from5

increased survival observed at termination i n male mice at 1,000 ppm as compared to controls (55 versus 45 in the surviving male controls). The incidences of hepatocellular neoplasms in terminally sacrificed male mice were 5/45 or 11%, 3/53 or 6%, 8/55 or 15% and 18/54 or 33%, at respective treatme nt levels of 0, 250, 1,000 and 7,000 ppm.

For females, whereas the incidence of hepatocellular adenoma was the same (2/65 or 3.1%) at 7,000 ppm and for controls, the incidence of hepatocellular carcinoma was slightly increased at 7,000 ppm (2/65 or 3.1%) versus control (0/65 or 0%). Since this incidence of hepatocellular carcinoma (3.1%) for females at 7,000 ppm is slightly above the maximum range of historical control data at both the testing facility (1.5%) and Charles River Laboratories (2.0%), the inc idence represents an equivocal finding. However, because this increase was very small, was not statistically significant, and did not demonstrate decreased latency compared to the controls, this finding was considered to represent only equivocal toxicolog ic significance.

Therefore, based on the weight

- of

- the

- evidence analysis, the NOAEL for oncogenicity is 1,000 ppm (approximately 190 mg/kg of b.w./day, calculated from food consumption data and nominal concentrations) based on the increased incidence of h epatocellular neoplasms observed in male mice at 7,000 ppm, as compared to controls.

In summary, long

- term exposure studies with metrafenone in dogs, rats and mice resulted in increased liver weights with corresponding changes in clinico

- chemical paramete rs. Microscopic pathological changes were identified in the liver, kidney, and spleen for rats and/or mice. The main target organ was identified as the liver in all species. Additionally, increased incidences of primary hepatocellular neoplasms were obse rved at the highest
doses in rats and mice.

6. Animal metabolism. M etrafenone was rapidly absorbed and efficiently excreted following oral administration in the rat. The amount of absorption ranged from approximately 89 to 92% of the administered dose of 10 mg/kg b.w. Most of the

administered dose was eliminated via bile within 72 hours (85.2 to 90.1%) and feces within 7 days (84.1 to 98.8%), with a small amount (0.69 to 6.6%) in urine. metrafenone

- related residues showed no potential for accumulation as <1.2% of the applied dose was retained over seven days, with highest levels of residues found in the liver, GI tract, plasma, blood, kidney, and fat. The tissue retention of the orally administered dose was less than 2% at
48

- 72 hours and less than 1.2% at 168 hours. metrafenone was extensively metabolized in the rat to multipl e metabolites formed via demethylation of the aromatic methoxy

- group(s) followed by mono

- O

- glycosidation, hydroxylation of the bromophenyl ring, and hydroxylation of the methyl substituent to hydroxymethyl followed by O

- glycosidation or

further oxidation t o aldehyde or lactone.

7. Metabolite toxicology

. In plant metabolism studies conducted in grapevines with

metrafenone , the parent compound was the principal residue in grapes. metrafenone is metabolized through methyl and ring oxidative biotransformatio ns, followed by enzymatic glucoside conjugation reactions to yield the conjugates from their corresponding aglycons. All major metabolites, which were present at very low levels, are considered non

- relevant6

as all were detected in the rat metabolism study as aglycons or conjugates, and can therefore be considered as not toxicologically significant. Thus, only parent metrafenone is considered relevant to define the residue in plants.

The results from a hydrolysis study designed to simulate different indus trial and household processes (pasteurization, brewing, boiling and sterilization) showed that metrafenone is stable. Therefore, metrafenone as unchanged parent is proposed as the relevant residue in grapes and industrial or household preparations of grap es.

Since metrafenone is not registered for use in the United States, the toxicity of metabolites formed in matrices other than the raw or processed treated commodity (e.g., water, soil) is

not relevant.

8. Endocrine disruption

. Data from the reproduction / developmental toxicity and

short

- and long

- term repeated dose toxicity studies with metrafenone in the rat, rabbit, mouse, or dog, do not suggest any endocrine disruption activity. This information is based
on the absence of a ny treatment

- related effects from the histopathological examination of endocrine organs as well as the low level of concern for possible effects on fertility, reproductive performance, or any other aspect of reproductive function, or on growth and developm ent of the offspring.

C. Aggregate Exposure

1. Dietary exposure. Assessments were conducted to evaluate the potential risk due to chronic dietary exposure of the U.S. population to residues of m etrafenone. The U.S. EPA has not established an acute reference dose for either the general population or females ages 13

– 49 years because no study demonstrated evidence of toxicity from a single dose exposure for these populations. Therefore, an acute exposure ris k evaluation is not required. The chronic assessment was conducted using all currently established tolerances
for metrafenone listed in 40CFR180.624 , the pending tolerance for the Pome Fruit Crop Group 11

- 10 of 1.5 ppm , and the proposed new tolerances for crop group 8

– fruiting vegetables at 1.0 ppm, crop group 9

– cucurbit vegetables at 0.5 ppm, crop subgroup 12

- 12A

– cherry subgroup at 2.0 ppm, crop subgroup 12

- 12B

– peach subgroup at 0.7 ppm, hops at 70 ppm, and apricots at 0.7 ppm , and crop subgroup 13

- 07F

– small fruit vine climbing except fuzzy kiwifruit at 4.5 ppm

.

i. Food. The dietary assessment analysis followed an initial tier approach using 100% crop treated and current or proposed tolerance values for all commodities. D i etary exposure assessments were conducted using Dietary Exposure Evaluation Module (DEEM

FCID Ver 3.1 8 ).

Acute Dietary Exposure Assessment
An acute assessment was not conducted because there are no relevant toxicological endpoints for acute dietary expos ure and a risk assessment is not required.

Chronic Dietary Exposure Assessment7

Results of the chronic exposure estimates were compared against the chronic Population Adjusted Dose (cPAD) of 0.25 mg/kg b.w./day that was based on the NOAEL from the rat chronic toxicity study, a safety factor of 100, and n o additional FQPA safety factor is required.

Results of the chronic dietary exposure assessments are listed in Table 1. The highest chronic dietary exposure of 11.8% of the cPAD was for children 1

- 2 years old

.

Table 1. Chronic Dietary Food Exposure Assessment for Metrafenone.

Population Exposure
Estimate %cPAD

Subgroups (mg/kg b.w./day)
US Population 0.005349 2.1 All infants (< 1 year) 0.021824 8.7

Children 1

- 2 0.029566 11.8

Children 3

- 5 0.017028 6.8

Children 6

- 12 0.007348 2.9

Youth 13

- 19 0.002893 1.2

Adults 20

- 49 0.003558 1.4 Adults 50+ yrs 0.003375 1.4

Females 13

- 49 yrs 0.003025 1.2

The results in Table 1 demonstrate there are no unreasonable risk concerns for any subpopulation based on established and new uses, and that the results clearly meet the FQPA standard of no unreasonable adverse effect.

ii. Drinking water

. The drinking water exposure values used in this assessment are from the most recent U.S. EPA risk assessment for Grapes (U.S. EPA, March 1, 2010 “Metrafenone: Human Health Risk Assessment for Foliar Use on Grape”). The water values calculated by EPA are the higher values than the p ending and pro posed new uses

. The chronic surface water concentration used in the human exposure assessment was 2 2 .82 ug/L.

Drinking water chronic exposure w as assessed based on a metrafenone water concentration
of 2 2. 82 ug/L using drinking water consumption
, and body weights reported in CSFII, using DEEM

- FCID Ver 3.1 8 software. The chronic estimated water exposure values are
summarized in Table 2.

Table 2. Summary of chronic dietary exposure assessment for drinking water considering
direct and indirect sources.
Population Subgroups Exposure Estimate (mg/kg b.w./day) %cPAD8

US Population 0.000478 0.2 All infants (< 1 year) 0.001232 0.5

Children 1

- 2 0.000689 0.3

Children 3

- 5 0.000581 0.2

Children 6

- 12 0.000419 0.2

Youth 13

- 19 0.000348 0.1

Adults 20

- 49 0.000477 0.2 Adults 50+ yrs 0.000471 0.2

Females 13

- 49 yrs 0.000475 0.2 %cPAD = percent of chronic population adjusted dose Exposure based on the maximum estimated water concentration of 2 2. 82 ug/L

Acute Aggregate Exposure (Food + Water ) An acute assessment was not needed because there are no relevant toxicological endpoints for acute dietary exposure and an aggregate risk assessment is not required.

Short

- and Intermediate Aggregate Exposure (Food + Water + Residential)
Metrafenone is not registered for any use which will result in residential exposure. Therefore, a short

- or intermediate

- term exposure and aggregate risk evaluation is not required.

Chronic Aggregate Exposure (Food + Water) The aggregate chronic risk includes residue s of metrafenone from food and water (Table 3). The results demonstrate there are no unreasonable risk concerns for any subpopulation based on established and new uses, and that the results clearly meet the FQPA standard of
no unreasonable adverse effect

.

Table 3. Estimated chronic aggregate exposure and risk of Metrafenone

Population Subgroup cPAD (mg/kg/day) Total Exposure,

Food and

Water (mg/kg/day) %
cPAD

US Population 0.25 0.005827 2.3 All infants (< 1 year) 0.25 0.023056 9.2

Children 1

- 2 0.25 0.030255 12.1

Children 3

- 5 0.25 0.017609 7.0

Children 6

- 12 0.25 0.007767 3.1

Youth 13

- 19 0.25 0.003241 1.3

Adults 20

- 49 0.25 0.004035 1.6 Adults 50+ yrs 0.25 0.003846 1.5

Females 13

- 49 yrs 0.25 0.0035 00 1.4
]9

2. Non

- dietary exposure

. Metrafenone is not registered for any use which will result

in non

- dietary residential exposure.

D. Cumulative Effects

At this time, there is no available information to indicate that metrafenone or its metabolites have a common mechanism of toxicity with other substances. Therefore, there is no reason to include this pesticide or its metabolites in a cumulative risk assessment. For the purposes of this tolerance action EPA has not assumed that metrafenone and its
metabolites have a common mechanism of t oxicity with other substances.

E. Safety Determination

1. U.S. population. Results of the analysis demonstrate no unreasonable risk

concerns for the U.S. population based on established and new proposed uses, and that the results clearly meet the FQPA standard of no unreasonable adverse effect.

2. Infants and children

. Results of the analysis demonstrate no unreasonable risk

concerns for any U.S. population including infants and children based on established and

new proposed uses, and that the results clearly meet the FQPA standard of no unreasonable adverse effect

.

F. International Tolerances

No maximum residue levels (MRLs) have been established for m etraf enone by the
Codex Alimentarius Commission (CODEX) or in Mexico.