UNITED STATES ENVIRONMENTAL PROTECTION AGENCY

WASHINGTON, D.C. 20460

OFFICE OF PREVENTION, PESTICIDES

AND TOXIC SUBSTANCES

MEMORANDUM

DATE:		June 27, 2007

SUBJECT:		Bromonitrostyrene:  Toxicology Disciplinary Chapter for the
Issuance of the Reregistration Eligibility Decision (RED) Document.

			Case No.:

			PC Code: 101401

DP Code: 338740

FROM:		Jenny J. Tao

	 		Senior Toxicologist

 		Risk Assessment and Science Support Branch (RASSB)

	 		Antimicrobials Division (7510P)

TO:			ShaRon Carlisle, Chemical Review Manager

Diane Isbell, Team Leader

			Mark Hartman, Chief

			Regulatory Management Branch II

			Antimicrobials Division (7510P)

THROUGH:		Norm Cook, Chief

	 		Risk Assessment and Science Support Branch

	 		Antimicrobials Division (7510P)

TRADE NAME:

REGISTRANT:	The Dow Chemical Company

Attached is the Toxicology Disciplinary Chapter for Bromonitrostyrene
for the purpose of issuing a Reregistration Eligibility Decision (RED)
document.

Bromonitrostyrene

PC Code: 101401

Toxicology Disciplinary Chapter for the Reregistration Eligibility
Decision (RED)

Document

TABLE OF CONTENTS

0.0
BACKGROUND……………………………………………………
………………………..4

1.0 HAZARD
CHARACTERIZATION………………………………………………
………..5

2.0 TOXICOLOGY DATA
REQUIREMENTS..……………………………………………...7

3.0 DATA
GAP(S)………………………….……………………………
…………………….....8

4.0 HAZARD
ASSESSMENT……………………………………………………
……………...9

 	4.1 Acute
toxicity………………………………………………………
………………….9

	4.2 Subchronic
toxicity………………………………………………………
…………..10

	4.3 Prenatal developmental
toxicity……….…………………………..…………………1
3

	4.4 Reproductive
toxicity………………………………………………………
………...15

	4.5 Chronic
toxicity………………………………………………………
……………...15

	4.6
Carcinogenicity…………………………………………………
……………………15

	4.7
Mutagenicity……………………………………………………
……………………15

	4.8
Neurotoxicity…………………………………………………
……………………...19

	4.9 Metabolism and
pharmacokinetics……………………..…………………………
…19

5.0 TOXICITY ENDPOINT
SELECTION…………………….……………………………..20

	5.1 Toxicological Doses and Endpoint
Selection..……….…….………………………..20

	5.2 Dermal
Absorption…………………………………….………………
……………..23

	5.3 Classification of Carcinogenic
Potential…...……..………………………………….23

6.0 FQPA
CONSIDERATIONS……………….…………………………………
……………26

	6.1 Special Sensitivity to Infants and Children
………………………………………….26

6.2 Developmental Toxicity Study
Conclusions………………………………………....26

	6.3 Reproductive Toxicity Study
Conclusions…………………………………………..27

6.4 Pre- and/or Post-natal
Toxicity………...…………………………………………….
27

	6.5 Recommendation for Developmental Neurotoxicity
Study………….………………27

7.0
REFERENCES..............................................................
.........................................................28

8.0 APPENDICES	31

8.1 Toxicity Profile
Summary………………………………………………………
……	32

		8.1.1	Acute Toxicity
Table…………………………….………………………32

8.1.2	Subchronic, Chronic and Other Toxicity
Table..………………………...32

0.0	BACKGROUND

β-bromo-β-nitrostyrene, BNS) is an aromatic nitro-vinyl halide.  The
cis and trans isomers occur as yellow solids that are soluble in most
organic solvents.  Its solubility in water is low.  Bromonitrostyrene is
a wide-spectrum organo-nitrogen biocide and is used as an fungicide,
antimicrobial agent, and a preservative.  Bromonitrostyrene’s uses as
a preservative include industrial lubricants, polymer emulsions, aqueous
emulsions, cutting oils, acrylic-based paints, starch-based adhesives,
and fuel oil.  It is most frequently used as a fungicide to combat the
formation of slime in metalworking fluids, recirculating water cooling
systems and in paper and pulp mill operations.  Its use in paper and
pulp mill operations may result in indirect contact with food even
though the Registrant stated that the food use applications currently on
the product labels are not supported (Ingram, 2006).

β-Bromo-β-nitrostyrene

CAS No. 7166-19-0

1.0	HAZARD CHARACTERIZATION

Bromonitrostyrene has a moderate to severe acute toxicity via the oral
and inhalation routes (both Toxicity Category II) and a moderate acute
toxicity by the dermal route of exposure (Toxicity Category III).
Bromonitrostyrene causes moderate to severe irritation to the eyes
(Toxicity Category II) and is corrosive to the skin (Toxicity Category
I).  It exhibited a moderate potential to produce dermal sensitization
in guinea pigs.

β-bromo-β-nitrostyrene, clinical signs of toxicity including diarrhea,
lethargy, ruffled fur, weight loss, nasal and eye discharge, oral and
anal discharge, and abnormal breathing were observed in rats at the
dosage level at which mortality was also observed.  Body weight gain,
final mean body weights, absolute and relative thymus organ weights were
lower, but there were no corresponding gross or microscopic pathology.
Hematological evaluations indicated mild anemia and monocytosis likely
related to inflammatory and ulcerative lesions were noted in the
gastrointestinal tract.  Clinical chemistry showed lower alkaline
phosphatase, serum total protein and albumin concentrations.
Histopathological lesions were noted in the forestomach, glandular
stomach, cecum, nasal passages, and testis with males more adversely
affected than females.

In a 4-week oral toxicity study in mice (also conducted by NTP),
bromonitrostyrene was found to cause mortality (mid-high dose group) as
well as clinical signs of toxicity including diarrhea and ruffled fur in
males and lethargy in males and females (high dose group).  There were
no treatment-related effects in final mean body weights or mean body
weight gains.  Hematological evaluations indicated responsive anemia in
males (mid-high dose group) likely related to inflammatory lesions noted
in the gastrointestinal tract of these mice.  Treatment-related
histopathological lesions were observed in the forestomach and
gallbladder mucosa (mid-high and high dose groups), and in the testis
(high dose males).

Bromonitrostyrene was tested in a 21-day dermal toxicity study in
rabbits.  Dose-related dermal irritation (erythema, edema, atonia, and
desquamation) was seen in all treatment groups after the first week of
treatment.  The most severe effects (necrosis and fissuring) were
observed in the female which was killed in moribund condition on day 9.
The dermal responses generally decreased in severity in the second and
third week of study, and only very slight or slight erythema with little
or no edema and generally moderate atonia and desquamation remained at
the end of the study.  Microscopic findings of treated skin from the
high-dose animals included minimal to slight hyperkeratosis and minimal
to moderated surface accumulation of inflammatory cells/cell debris and
minimal to moderate acute/subacute inflammation of the dermis (in
increased incidence and severity relative to controls).  Minimal
congestion of the dermis and hyperplasia and vesicle formation involving
the stratified epithelium were also revealed.

Systemic toxicity was observed only in the high dose group, evidenced by
mortalities (sacrifice in a moribund condition) in two females, reduced
body weight gains or weight losses (the two females which were
sacrificed showed substantial antemortem weight losses) and poor food
consumption.  Statistically significant elevations in serum potassium
levels were seen in high-dose males and females at termination; these
were more pronounced (p≤0.01) in females.  Because of the severity and
uncertainty of the effects seen in this 21-day dermal study (true
systemic effects or secondary to the dermal effects), particularly at
the high-dose level (death), a 90-day dermal study in rabbits is needed.

In a developmental toxicity study in rats by gastric intubation from
days 6 through 15 of gestation, an increased incidence of excessive
salivation was in the mid-dose group.  A further increased incidence of
excessive salivation and additional symptoms including moist rales,
anogenital staining, a reduced (21.2% below the control value, not
statistically significant) mean weight gain occurred in the high-dose
group.  In addition, two dams died at this dose level only two days
after dosage was initiated.  Mean fetal body weights were significantly
reduced in the high-dose group.  There was no indication of any effect
involving external or visceral anomalies.  The fetal (litter) skeletal
malformations were seen in one control fetus, three low-dose fetuses and
four high-dose fetuses, mostly wavy ribs.

In a NTP performed microbial gene mutation assay, ß-brom-ß-nitrostyrol
caused a dose-dependent increase in the mean revertant frequency over
the value of the solvent control in Salmonella typhimurium strains TA98
and TA100 in the absence of metabolic activation system. In another two
independently performed microbial gene mutation assay,
ß-brom-ß-nitrostyrol induced a positive, dose-related mutagenic
response in strain TA100 at the histidine locus both in the absence and
presence of S9 mix.

ß-bromo-ß-nitrostyrene was positive as a clastogen in an in vitro
mammalian chromosome aberration test with Chinese hamster ovary (CHO)
cells, and was positive in inducing frequency of micronuclei (p≤0.005,
but not in a dose-response manner) in peripheral blood erythrocytes in
male mice in an in vivo mammalian cytogenetics assay performed by the
NTP and negative in a guideline in vivo mouse micronucleus assay.

There were no evidence that ß-bromo-ß-nitrostyrene induced a genotoxic
response in an unscheduled DNA synthesis (UDS) assay with primary rat
hepatocytes.

No data are available for reproductive toxicity, chronic toxicity and
carcinogenicity of ß-bromo-ß-nitrostyrene.

Additional studies are required to assess exposure in the occupational
setting for the current registered uses: a 90-day dermal and inhalation
study, carcinogenicity and chronic toxicity studies, a developmental
study in a non-rodent species and a 2-generational reproductive toxicity
study.

2.0	TOXICOLOGY DATA REQUIREMENTS

  SEQ CHAPTER \h \r 1 The Toxicology database for bromonitrostyrene is
listed in the following Table 1.

Table 1.  Toxicologic Data Requirements for Bromonitrostyrene

Test

	MRID	Technical

Required	Satisfied

870.1100	Acute Oral Toxicity (Rat)

870.1200	Acute Dermal Toxicity (Rabbit)

870.1300	Acute Inhalation (Rat)

870.2400	Primary Eye Irritation (Rabbit)

870.2500	Primary Dermal Irritation (Rabbit)

870.2600	Dermal Sensitization (Guinea pig)  	41603501 and 41603506

44524506

43452701

44524509

41744601, 44178401 and 44524508

44524510 and 45094806	yes

yes

yes

yes

yes

yes	yes

yes

yes

yes

yes

yes

870.3100	Oral Subchronic

870.3250     90-Day Dermal (Rabbit)

870.4365     90-Day Inhalation	NTP studies

40830101

	yes

yes

yes	yes

no

no

870.3700	Developmental Toxicity (Rat)

870.3700    Developmental Toxicity (Rabbit)

870.3800	Reproduction	40691402 and 40728701

	yes

yes

yes	yes

no

no

870.4100a   Chronic (Rat)

870.4100b   Chronic (Mouse)

870.4200a   Carcinogenicity (Rat)

870.4200b   Carcinogenicity (Mouse)

	yes

yes

yes

yes	no

no

no

no

870.5100	Mutagenicity – Bacterial Reverse                      Gene
Mutation assay

870.5375	Mutagenicity – Chromosome
aberrations  (CHO) MRID

870.5395	Mutagenicity – Mammalian
erythrocyte micronucleus test                                (Mouse)

870.5550	Mutagenicity – Unscheduled DNA                    synthesis
in primary rat hepatocytes 	40691401 and NTP study

40641309

NTP study and 47010001

40641310 and 46972603

	yes

yes

yes

no	yes

yes

yes

3.0	DATA GAPS

  SEQ CHAPTER \h \r 1 There are data gaps in the hazard database for
bromonitrostyrene based on the current use patterns.  Due to the
potential for inhalation exposure in the occupational setting, a 90-day
inhalation toxicity study must be performed with bromonitrostyrene.

Risks from the metalworking fluid use of bromonitrostyrene cannot be
adequately characterized without conducting of chronic toxicity studies
in the rat and mouse as well as carcinogenicity studies in these two
species.  Metalworking fluid use is considered a high exposure
antimicrobial use pattern and requires chronic toxicity and
carcinogenicity data.  In addition, the positive results of in vitro and
in vivo genetic toxicity studies warrant a carcinogenicity study.

  SEQ CHAPTER \h \r 1 There are no data on the reproductive toxicity of
bromonitrostyrene.  The data for characterizing the developmental and
reproductive toxicity of bromonitrostyrene are limited to one
developmental toxicity study in rats.  A non-rodent species needs to be
tested based on the current registered uses of bromonitrostyrene.  A
reproductive toxicity study is also necessary to assess any effects on
fertility and reproduction, and is required to support the current uses
of bromonitrostyrene.

In conclusion, the following studies are required to complete the hazard
database for bromonitrostyrene to support its current uses: 1) a 90-day
dermal and inhalation toxicity study; 2) chronic toxicity studies in the
rat and mouse; 3) carcinogenicity studies in the rat and mouse; 4) a
developmental study in rabbits; and 5) a reproductive toxicity
study.4.0	HAZARD ASSESSMENT

Acute Toxicity

Adequacy of Database for Acute Toxicity:  The acute toxicity database
for bromonitrostyrene is considered complete.  No additional studies are
required at this time.

The acute oral toxicity of bromonitrostyrene is moderate to severe
(Toxicology Category II), with mortality, urinary and fecal staining,
soft stool, nasal and/or oral discharge, unthrifty coat, hypoactivity,
and decreased food consumption observed in acute oral toxicity studies
(MRIDs 41603501 and 41603506).  The acute dermal toxicity of
bromonitrostyrene is moderate (Toxicity Category III); effects such as
black discoloration, eschar formation, and scabs were noted, in addition
to lacrimation (MRID 44524506).  Bromonitrostyrene has a moderate to
severe toxicity via the inhalation route (Toxicity Category II),
substantial weight losses and frequent respiratory and secretory
symptoms were reported (MRID 43452701).  Bromonitrostyrene is a
Toxicology Category II eye irritant.  Conjunctival, corneal, and iridial
irritation were observed and positive scores for opacity and ulceration
were obtained in the primary eye irritation study (MRID 44524509).
Severe dermal irritation effects (Toxicology Category I) were noted in
the primary dermal irritation studies (MRIDs 41744601, 44178401, and
44524508), including erythema, subepidermal necrosis, and subepidermal
damage.  Bromonitrostyrene exhibited a moderate potential to produce
dermal sensitization in guinea pigs (MRIDs 44524510 and 45094806).

The acute toxicity data for Bromonitrostyrene is summarized in Table 2.
below.

Table 2.  Acute Toxicity Profile for Bromonitrostyrene

Guideline Number	Study Type/

Test substance (% a.i.)	MRID Number/

Citation	Results	Toxicity Category

870.1100

	Acute Oral- Rat

Giv 2-0820 (99.1% a.i.) 	41603501	LD50(M): 446 mg/kg LD50(F): 466 mg/kg
LD50(M/F): 457 mg/kg	II

870.1100 	Acute Oral- Rat

ß-bromo-ß-nitrostyrene

(25.1% a.i.)	41603506	LD50(M): 1837 mg/kg LD50(F): 1464 mg/kg LD50(M/F):
1678 mg/kg	III

870.1200

	Acute Dermal- Rabbit

Giv-Gard BNS (25% a.i.) 	44524506	LD50: > 2000 mg/kg bw	III

870.1300

	Acute Inhalation- Rat

Bromonitrostyrene

(98.2% a.i.)	43452701	LC50(M): 0.14 mg/L

LC50 (F): 0.30 mg/L

LC50 (M/F): 0.20 mg/L	II

870.2400

	Primary Eye Irritation- Rabbit

Giv-Gard BNS (25% a.i.)	44524509	Moderate to Severe Irritant	II

870.2500

	Primary Dermal Irritation- Rabbit

ß-bromo-ß-nitrostyrene (25.1% a.i.)	41744601	Corrosive	I

870.2500

	Primary Dermal Irritation- Rabbit           Bromonitrostyrene (25%
a.i.)	44178401	Corrosive	I

870.2500

	Primary Dermal Irritation- Rabbit           Giv-Gard BNS (25% a.i.)
44524508	Severe, Reversible Dermal Irritation	II

870.2600	Dermal Sensitization – Guinea Pig

Giv-Gard BNS (25% a.i.)	44524510	Moderate Sensitization	N/A

870.2600	Dermal Sensitization – Guinea Pig

Spectrum RX4101 (9.2% a.i.)	45094806	Moderate Sensitization	N/A

Subchronic Toxicity

Adequacy of Database for Subchronic Toxicity:  The database for
subchronic toxicity is considered incomplete.    SEQ CHAPTER \h \r 1
Although a subchronic oral and dermal toxicity study are available, a
90-day inhalation toxicity study is required in order to adequately
assess inhalation risks and occupational exposure concerns for the
current registered use patterns.

	90-Day Oral Toxicity – Rat

In a 4-week oral toxicity study (NTP study), β-bromo-β-nitrostyrene
(trans isomer; 99% a.i., Lot # C-61559) was administered to 10 F344/N
rats/sex/dose by gavage for five days per week for 4 weeks at dose
levels of 0, 37, 75, 150, 300 or 600 mg/kg bw/day.  An additional
supplemental 10 rats/sex/dose were utilized for interim clinical
pathology evaluations.

Mortality was observed in the 150 mg/kg and higher doses male group and
in 300 mg/kg and higher doses female group within the first week of
treatment; all rats in the 600 mg/kg dose level died.  Clinical signs of
toxicity including diarrhea, lethargy, ruffled fur, weight loss, nasal
and eye discharge, oral and anal discharge, and abnormal breathing were
observed in rats treated at 150 mg/kg and higher doses.  Body weight
gain and final mean body weights were lower in 300 mg/kg males.
Absolute and relative thymus organ weights were lower in 300 mg/kg rats,
but there were no corresponding gross or microscopic pathology.
Hematological evaluations indicated mild anemia and monocytosis likely
related to inflammatory and ulcerative lesions that were noted in the
gastrointestinal tract.  Clinical chemistry showed lower alkaline
phosphatase, serum total protein and albumin concentrations.
Histopathological lesions were noted in the forestomach, glandular
stomach, cecum, nasal passages, and testis with males more adversely
affected than females.  The LOAEL is 75 mg/kg/day in males and 150
mg/kg/day in females, based on histopathology findings in the
forestomach.  The NOAEL is 37 mg/kg/day in males and 75 mg/kg/day in
females.

This study is classified as Acceptable – Nonguideline.

870.3100	90-Day Oral Toxicity – Mouse

In a 4-week oral toxicity study (NTP study), β-bromo-β-nitrostyrene
(trans isomer, 99% a.i., Lot # C-61559) was administered to 10 B6C3F1
mice/sex/dose in 5 mL/kg body weight of corn oil by oral gavage at dose
levels of 0, 37, 75, 150, 300 or 600 mg/kg bw/day.

Mortality was observed in one 300 mg/kg male mouse and in all 600 mg/kg
mice.  Clinical signs of toxicity were observed at 600 mg/kg and
included diarrhea and ruffled fur in males and lethargy in males and
females.  There were no treatment-related effects in final mean body
weights or mean body weight gains.  Hematological evaluations indicated
responsive anemia in 300 mg/kg males likely related to inflammatory
lesions noted in the gastrointestinal tract of these mice.
Treatment-related histopathological lesions were observed in the
forestomach and gallbladder mucosa of ≥300 mg/kg mice, and in the
testis of 600 mg/kg males.  The LOAEL is 300 mg/kg/day based on
microscopic pathology of the forestomach and gallbladder.  The NOAEL is
150 mg/kg/day.

This study is classified as Acceptable – Nonguideline.

870.3100	90-Day Oral Toxicity – Rat

In a subchronic oral toxicity study (MRID 00150525), GIV 0820
(bromonitrostyrene; purity and Lot # not reported) was administered to 8
CFE albino rats/sex/dose in the diet at dose levels of 0, 500, 1000, or
2500 ppm (0, 50, 110, and 300 mg/kg/day) for at least 30 days.

No adverse, treatment-related effects were observed on mortality,
clinical signs, body weight, food consumption, clinical chemistry,
urinalysis, gross pathology, or histopathology.

In the ≥1000 ppm males, a decrease (↓51-63%) in terminal WBC counts
was observed when compared with controls.  However, in the absence of
other relevant data, this effect was considered to be equivocal.

The kidneys from female rats fed 110 mg/kg/day and males fed 300
mg/kg/day showed increased organ-body weight ratios as were the adrenals
from the males fed 110 mg/kg/day.  However, no toxicity or microscopic
findings were noted.  The LOAEL was not established.  The NOAEL is 2500
ppm (300 mg/kg/day).

This study is classified as Unacceptable because of its major
deficiencies including not reported purity.

Short-Term Oral Toxicity (Range-Finding) – Rat

In this range-finding study (MRID 00150524), GIV 0820
(bromonitrostyrene; purity and Lot # not reported) was administered to 3
Charles River strain rats/sex/dose in the diet at dose levels of 0,
1000, 2500, or 5000 ppm (approximately equivalent to 0/0, 107/94,
237/253, and 370/368 mg/kg/day in males/females) for at least 7 days.
On Day 8, all animals were returned to the control diet and were
observed until Day 14.

No treatment-related effects were observed on mortality, clinical signs,
body weights, organ weights, or gross pathology.

At ≥2500 ppm, food efficiency ratios were decreased by 26-36% in both
sexes.  Additionally at 5000 ppm, body weight gains (Days 0-7) were
decreased by 48% in males and 54% in females.

The LOAEL is 2500 ppm (equivalent to approximately 237/253 mg/kg/day in
males/females) based on decreased food efficiency ratios in both sexes.
The NOAEL is 1000 ppm (equivalent to approximately 107/94 mg/kg/day in
males/females).

This study is classified as Unacceptable for a preliminary range-finding
oral toxicity study in the rat.  Purity was not reported and dose
formulations were not analyzed.  Other major deficiencies were also
observed.

870.3200	90-Day Dermal Toxicity Study – Rabbit

In a 21-day dermal toxicity study (MRID 40830101), Giv-Gard 2-0820
(99.1% a.i.) was dermally applied (clipped skin up to 10% of the body
surface area) to 5 New Zealand white rabbits/sex/dose at dose levels of
0 (vehicle only), 10, 50, and 100 mg/kg/day for 6 hours/day; 5 days/week
for 3 weeks (total of 15 exposures).  The test material was applied as a
suspension in dimethyl phthalate at a constant dose of 5 ml/kg.

Dose-related dermal irritation (erythema, edema, atonia, and
desquamation) was seen in all treatment groups after the first week of
treatment.  The most severe effects (necrosis and fissuring) were
observed in the female which was killed in moribund condition on day 9.
The dermal responses generally decreased in severity in the second and
third week of study, and only very slight or slight erythema with little
or no edema and generally moderate atonia nad desquamation remained at
the end of the study.  Dermal irritation scores were recorded pretest,
on day 8 (after 5 exposures), day 15 (after 10 exposures) and day 22
(after 15 exposures).  The most pronounced dermal irritation in all
treated groups was observed on day 8 (mean erythema scores: 10
mg/kg/day: 0.5; 50 mg/kg/day: 1.7; 100 mg/kg/day: 3.4).  Microscopic
findings of treated skin from the high-dose animals included minimal to
slight hyperkeratosis and minimal to moderated surface accumulation of
inflammatory cells/cell debris and minimal to moderate acute/subacute
inflammation of the dermis (in increased incidence and severity relative
to controls).  Minimal congestion of the dermis and hyperplasia and
vesicle formation involving the stratified epithelium were also
revealed.

Systemic toxicity was observed only in the high dose (100 mg/kg/day)
group, evidenced by mortalities (sacrifice in a moribund condition) in
two females, reduced body weight gains or weight losses (the two females
which were sacrificed showed substantial antemortem weight losses) and
poor food consumption.  Statistically significant elevations in serum
potassium levels were seen in high-dose (100 mg/kg/day) males and
females at termination; these were more pronounced (p≤0.01) in
females.

The systemic LOAEL is 100 mg/kg/day, based on mortality in 2/5 females,
reduced mean body weights in both sexes, and statistically significant
elevations in serum potassium levels in both males and females at
termination.  The systemic NOAEL is 50 mg/kg/day.  The dermal irritation
NOAEL is ≤ 10 mg/kg/day (LDT), based on dermal irritation effects
observed at all dose levels.

This study is classified as Acceptable – Guideline.

There is some question as to whether the effects seen in this study were
actually due to systemic toxicity, or were secondary to the dermal
effects.  However, it can be assumed, as a worst-case scenario that
these effects were due to systemic toxicity.  The study does not define
a NOAEL in terms of the dermal irritation potential of this test
substance, as dermal effects were present even in the low-dose (10
mg/kg/day) group, but the concern is with systemic effects.

Because of the severity and uncertainty of the systemic effects of this
21-day dermal study, particularly at the high-dose level (death), a
90-day dermal study in rabbits is needed.

4.3	Prenatal Developmental Toxicity

Adequacy of Database for Prenatal Developmental Toxicity:  The database
fro developmental toxicity is considered incomplete.  There is only one
developmental toxicity study (MRID 40728701, with accompanying
range-finding study 40691402) in rats available for this chemical. A
developmental toxicity study in non-rodent species is required to
fulfill the data requirement for the registered uses.

870.3700a	Prenatal Developmental Toxicity (Gavage) Study – Rat

In a developmental toxicity study (MRID 40728701), Giv 2-0820 (99.1%
ß-bromo-ß-nitrostyrene) was administered (as a suspension in corn oil)
to 24 or 25 mated female CDR  Sprague-Dawley derived rats/dose level by
gastric intubation at dose levels of 0 (vehicle only), 30, 75, and 150
mg/kg/day from days 6 through 15 of gestation.

There were no indications of any maternal toxicity at 30 mg/kg/day.  At
75 mg/kg/day there was an increased incidence of excessive salivation.
A further increased incidence of excessive salivation and additional
symptoms including moist rales, anogenital staining, a reduced mean
weight gain (21.2% below the control value, although not statistically
significant) occurred at 150 mg/kg/day.  In addition, two dams died at
this dose level only two days after dosage was initiated.

Mean fetal body weights were significantly reduced in the high-dose (150
mg/kg/day) group, and were somewhat reduced (not statistically
significant) at 75 mg/kg/day, with no indication of an effect on this
parameter at 30 mg/kg/day (mean body weights: controls: 3.67 g; 30
mg/kg/day: 3.69 g; 75 mg/kg/day: 3.53 g; 150 mg/kg/day: 3.35 g).  There
was no indication of any effect involving external or visceral
anomalies; the fetal (litter) incidences of skeletal malformations were
2/143 (2/22), 3/161 (1/24), 0/144 (0/24), and 8/137 (4/20) for the
controls, 30 mg/kg/day, 75 mg/kg/day and 150 mg/kg/day groups,
respectively.  The most common malformation was wavy ribs, seen in one
control fetus, three low-dose fetuses and four high-dose fetuses.

The maternal toxicity NOAEL is 75 mg/kg/day; the maternal LOAEL is 150
mg/kg/day (increased incidence of excessive salivation along with a
reduced in mean weight gain [21.2% below the control value but not
statistically significant] during the treatment period [6-15 days of
gestation]).

The developmental NOAEL is 75 mg/kg/day; the developmental LOAEL is 150
mg/kg/day (a statistically significant [p ≤ 0.01] decrease in mean
fetal body weight and a slight [not statistically significant] increased
incidence of skeletal malformations, mostly wavy ribs).

This study is classified as

Developmental Toxicity (Range-Finding) – Rat

In a developmental range-finding study (MRID 40691402), Giv 2-0820
(99.1% purity) was administered to 5 CD Sprague-Dawley derived mated
female rats/dose level by gastric intubation in corn oil at dose levels
of 0 (vehicle only), 30, 75, 150, 300, and 600 mg/kg/day from days 6
through 15 of gestation.  Females were sacrificed on Day 20 of
gestation.

There was no maternal mortality at 30 or 75 mg/kg/day.  At 150 mg/kg/day
one female was found dead on day 9; it was not clear if this death was
related to dosage with the test material or was caused by an intubation
injury.  No other deaths occurred in this group.  At 300 mg/kg/day, 2/5
females were sacrificed moribund (gestation days 8 and 11), and at 600
mg/kg/day 5/5 females died on gestation Days 7-10 (after receiving 1 to
4 doses of the test material).  During the treatment period, mean body
weight gains were similar in controls and the 30 and 75 mg/kg/day
groups, but were reduced (by 16.7%) in the 150 mg/kg/day group and (by
31%) in the 300 mg/kg/day group.  At termination, there was no
indication of fetotoxicity at doses of up to 300 mg/kg/day (no increased
number of late resorptions, no dead fetuses, no effect on mean fetal
body weight).

The study is classified as Acceptable – Nonguideline.

  	4.4	Reproductive Toxicity

Adequacy of Database for Reproductive Toxicity:  The database for
reproductive toxicity is considered incomplete.  There are no
reproductive toxicity data for bromonitrostyrene.  The assessment for
the reproductive and developmental toxicity of bromonitrostyrene can not
be completed with only one developmental toxicity study in rats.  A
2-generational reproductive toxicity study is required to assess any
effects on fertility and reproduction and to support the current uses of
this chemical.

4.5	Chronic Toxicity

Adequacy of Database for Chronic Toxicity:  The database for chronic
toxicity is considered incomplete.    SEQ CHAPTER \h \r 1 No chronic
toxicity data are available for bromonitrostyrene.  In order to address
the hazardous risks from the metalworking fluid use, chronic toxicity
studies in the rat and mouse are required.

Carcinogenicity

Adequacy of Database for Carcinogenicity:  The database for
carcinogenicity is considered incomplete.  There are no carcinogenicity
data for bromonitrostyrene.  A determination of carcinogenic potential
cannot be made based on the available data.  Metalworking cutting fluid
use triggers the requirement for carcinogenicity studies as described on
the 1987 Antimicrobial Data Call-In Notice.  In addition, the positive
findings of in vitro and inclusive results of in vivo genetic toxicity
studies warrant a carcinogenicity study.

Mutagenicity

Adequacy of Database for Mutagenicity:  The database for mutagenicity is
considered complete.  Several mutagenicity studies have been submitted
and reviewed by the Office of Pesticide Programs (OPP) and found
acceptable.  The summaries of these studies are provided below.

	Gene Mutation

In two independently performed microbial gene mutation assays (MRID
40691401), Salmonella typhimurium strains TA 1535, TA 1537, TA 1538, and
TA 98 were exposed to 0.01 to 3.33 µg/plate ß-Brom-ß-Nitrostyrol (>
92%) in the absence of S9 activation.  In addition, TA 100 was exposed
to concentrations ranging from 0.10 to 33.33 µg/plate.  In the presence
of S9 mix, TA 1535, TA 1537, TA 1538, TA 98, and TA 100 were exposed to
concentrations ranging from 1.00 to 333.3 µg/plate.  The S9 fraction
was derived from Aroclor 1254-induced male Wistar (strain CFHB) rat
livers and the test material was delivered to the test system in DMF
(not otherwise identified).

In a preliminary toxicity assay, there was complete cytotoxicity to
strain TA 98 at 10 µg/plate -S9, and at 333.33 µg/plate +S9.  There
was complete cytotoxicity to strain TA 100 at 33.33 µg/plate -S9, and
at 333.33 µg/plate +S9.  In the mutagenicity assays, there was complete
cytotoxicity for almost all strains at the highest dose levels tested
(3.33 µg/plate -S9; 333.33 µg/plate +S9) except TA 100, which was
tested at up to 33.33 µg/plate -S9, and 333.33 µg/plate +S9 and TA
1535 (no indication of cytotoxicity at 3.33 µg/plate -S9).  All strains
responded in the expected manner to the nonactivated and S9-activated
positive controls.  Under the test conditions, a positive, dose-related
mutagenic response was elicited in strain TA 100 at the histidine locus
both in the absence and presence of S9 mix.  There was, however, no
evidence that ß-brom-ß-nitrostyrol induced a mutagenic response in any
of the other strains (TA 1535, TA 1537, TA 1538, or TA 98) at any
nonactivated or S9-activated dose, although there is no indication that
strain TA 1535 was tested to sufficiently adequate levels in the absence
of S9 mix.

The study is classified as Partially Acceptable – Guideline.  It is
acceptable for all strains in the presence of S9 mix, and for all
strains except TA 1535 in the absence of S9 mix, and partly satisfies
the guideline requirement for a microbial gene mutation assay (84-2).
The assay with TA 1535 in the absence of S9 mix must be repeated, to
demonstrably cytotoxic levels.

In a NTP reverse gene mutation assay in bacteria, Salmonella typhimurium
strains TA97, TA98, TA100, and TA1535 were exposed to
β-bromo-β-nitrostyrene, (>95%), in an unknown solvent at
concentrations ranging from 0.3 to 200 µg/plate either in the presence
or absence of mammalian metabolic activation system using pre-incubation
method.  Two different mammalian metabolic activations were used,
derived from the livers of Aroclor 1254-induced Sprague-Dawley rats or
Syrian hamsters.

β-bromo-β-nitrostyrene was tested using TA100 by preincubation
techniques at half-log concentration intervals up to a maximum dose of
10 mg/plate in order to find the toxic concentration.  At least 5 doses
in triplicate were utilized and were repeated at least one week
following the initial test; however, the doses used were not reported.
A maximum of 0.05 ml solvent was added to each plate (Zeiger et al,
1992).

In the mutagenicity assay, slight toxicity was observed at the top dose
levels in all strains in both conditions.  In TA100 and TA98,
dose-dependent increases in the mean revertant frequency over the mean
revertant frequency of solvent control were observed in cultures without
metabolic activation system only.  An equivocal response was observed in
TA97 in cultures without S9.  The positive controls gave the appropriate
responses.  There was a concentration-related positive response of
induced mutant colonies over background in strains TA98 and TA100 in
cultures without metabolic activation system.

This study is classified as Acceptable – Nonguideline.

	Cytogenetics

In an in vitro mammalian chromosome aberration test (MRID 40641309),
Chinese hamster ovary (CHO) cells were exposed for approximately 7.25
hours to Giv 2-0820 (ß-bromo-ß-nitrostyrene, 99.1%) without activation
at concentrations ranging from 1.00 to 3.00 µg/ml in the first assay,
and 2.25 to 5.00 µg/ml in the second assay.  The test material was
delivered as a solution in DMSO.  Following exposure, cells were washed
and then exposed to 0.1 µg/ml Colcemid for 2.5 hrs, followed by
harvest.  With S9 activation, cells were exposed for 2 hrs to
concentrations of 0.997 to 7.48 µg/ml in the first assay; they were
then washed, followed by incubation for 17.8 hours with 0.1 µg/ml
colcemid present during the last 2.5 hrs of incubation.  Doses were
based on a preliminary range-finding study in which complete
cytotoxicity was observed at 3.33 µg/ml –S9 and at 33.3 µg/ml +S9,
with noticeable cell cycle delays at ≥ 998 ng/mL ± S9.

e was a significant (p ≤ 0.01) increase in % of cells with chromosomal
aberrations at only the next-to-highest dose level (4.99 µg/ml), but
not at the two lower dose levels (0.997 and 2.49 µg/ml) nor at the
highest dose level (7.48 µg/ml); however, there was a 50% reduction in
cell monolayer confluency at 7.48 µg/ml, and mitotic figures were
present in only one of two cultures.  The lack of a significant increase
in percentage of aberrant cells at 7.48 µg/ml may have been due to
cytotoxicity of the test material at this dose level, although it is
noted that a number of complex chromatid exchanges (including triradials
and quadriradials) typical of chemical clastogens were observed at both
4.99 and 7.48 µg/ml.  Triradials and quadriradials were also observed
following exposure to Giv 2-0820 in the absence of S9 activation.  Under
the conditions of this assay, Giv 2-0820 is positive as a clastogen.
Positive controls induced the appropriate responses.

This study is classified as Acceptable – Guideline.

β-bromo-β-nitrostyrene (>99%; Lot No. C-61559) in 5 mL/kg body weight
of corn oil at doses of 0, 37, 75, 150, 300 or 600 mg/kg.  Peripheral
blood cells were harvested 4 weeks post-treatment.

There were significant increases (p≤ 0.005) in micronucleated
normochromatic erythrocytes (MNCEs) in two of the four dosed groups of
males, although these increases did not show a clear dose-respondent
relationship, as shown by the trend analysis (p=0.520).  No significant
increases in MNCEs were reported at any dose in females.  There was a
significant increase in the frequency of micronucleated normochromatic
erythrocytes in peripheral blood of male mice after treatment time.

The positive controls information was not provided in the NTP report;
however, it was referenced to a study by MacGregor et al (1990) for the
study details.  In MacGregor et al. study, B6C3F1 mice were treated with
triethylenemelamine (1, 4, 16, or 64 μg/mL) or urethane (0.75 or 2.0
mg/mL) in drinking water for up to 90 days.  Sampling of peripheral
blood was performed before the addition of chemicals and after 45 days
of exposure, and both blood and bone marrow samples were obtained after
90 days of exposure.  All samplings and compounds produced clear
positive but nondose-response results.

β-bromo-β-nitrostyrene (99.9±0.05 mol %; Lot No. 395-99-A) in corn
oil at doses of 0, 75, 150, or 300 mg/kg.  An additional 6 mice were
dosed at 300 mg/kg and were used as possible replacements for animals in
this treated group in the event of death.  Bone marrow cells were
harvested at 24 hours after the final dosing.  Cyclophosphamide (CP) was
used as a positive control.

All animals survived the treatment period.  Also, no significant changes
in body weights or body temperatures were observed at any dose compared
to controls.  At 300 mg/kg/day, clinical signs of toxicity including
decreased, soft and watery feces was observed in 5/12 males, and
perineal soiling was observed in 7/12 males compared with 0/6 controls.

No statistically significant increases in the micronucleated
polychromatic erythrocytes (MN-PCE) frequency or % PCE were observed in
any treatment group when compared to controls.  The positive control
induced statistically significant increases (p≤0.05) in MN-PCEs
compared to the concurrent vehicle controls.

This study is classified as Acceptable – Guideline.

Other Genotoxicity

In an unscheduled DNA synthesis assay (MRID 40641310), primary rat
hepatocytes were exposed for 18 hours to doses of Giv 2-0820
(ß-bromo-ß-nitrostyrene, 99.1%)
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Concentrations ≥ 15 µg/ml resulted in cells which could not be
analyzed due to inadequate flattening on the slides.  Although it was
possible to analyze cells at 10 µg/ml, normal cell morphology was
present only at doses ≤ 2.5 µg/ml.  The positive control induced the
expected marked increase in nuclear labeling.  There was, however, no
evidence that Giv 2-0820 induced a genotoxic response.

The study is classified as Acceptable – Guideline.

In an in vivo/in vitro unscheduled DNA synthesis assay (MRID 46972603),
rat hepatocyte cultures were prepared from 4-7 male Fischer 344 rats
that were orally dosed (gavage, 20 mL/kg) once with
ß-bromo-ß-nitrostyrene (99.9±0.05 mol%; Lot No. 395-99-A) in corn oil
at doses of 0, 350, or 700 mg/kg.  Hepatocytes were harvested at 2.3 to
2.8 or 15.1 to 16.1 hours post-dosing.  N-dimethylnitrosamine (DMN) was
used as positive control.

ß-bromo-ß-nitrostyrene was tested up to 700 mg/kg.  The net nuclear
grain (NNG) counts in the treated animals (–1.57 to 0.91) were well
below the threshold of 5 or more NNG required for a positive response,
and the mean percent of cells in repair (>5 NNG/cell) in the treated
animals was only 1.67-6.33% in both trials.  The positive controls
induced the appropriate response in both trials.  There was no evidence
that unscheduled DNA synthesis, as determined by radioactive tracer
procedures (nuclear silver grain counts) was induced.

The study is classified as Acceptable – Nonguideline

4.8	Neurotoxicity

Adequacy of Database for Neurotoxicity:  These studies are not required
at this time.  From the available repeated-dose toxicity studies, there
was no evidence of neurotoxicity of bromonitrostyrene.  It is concluded
that there is no concerns for neurotoxicity resulting from exposure to
bromonitrostyrene based on the fact that no neurotoxicity findings in
the available studies.

	4.9	Metabolism and Pharmacokinetics

Adequacy of Database for Metabolism and Pharmacokinetics:  There is one
NTP study.  SEQ CHAPTER \h \r 1   SEQ CHAPTER \h \r 1

β-bromo-β-nitrostyrene (β carbon of the vinyl side chain labeled, 98%
a.i., 1.13 mCi/mmole, Lot No. 2014-148), a solution containing 3.8 mCi
[3H]-β-Bromo-β-nitrostyrene per milliliter of toluene (C-4 position
benzene ring labeled, 98% a.i., 1.25 Ci/mmole, Lot N o. 317-8), and
unlabeled β-Bromo-β-nitrostyrene (>99% a.i.; Lot No. 267) was
administered to groups of 3 to 4 male F344 rats/dose.  The oral study
rats were given a single gavage dose of 1.0, 10, or 100 mg/kg; the
intravenous study rats were injected with a single dose of 9.1 mg/kg bw;
and the dermal study rats were treated with a single dose of 0.1, 10, or
100 mg/cm2.  An additional group of 4 rats was treated orally for 4 days
with 100 mg/kg bw lincomycin and 100 mg/kg bw neomycin to deplete
intestinal microflora, after which the rats received a single oral dose
of 10 mg/kg bw by gavage.  Urine, feces, expired air, and tissues were
collected from all rats, bile was collected from two rats, and
gastrointestinal and urinary tract samples were collected from rats in
the oral and dermal studies, at various time points from 0 to 72 hours
after dosing.

C]-β-bromo-β-nitrostyrene.

 It is likely that significant absorption of
[3H/14C]-β-bromo-β-nitrostyrene administered from the oral route
occurs in the upper gastrointestinal (GI) tract and that unabsorbed
parent compound is degraded by intestinal microflora.  Only low levels
of radioactivity are retained in tissues following exposure to
[3H/14C]-β-bromo-β-nitrostyrene by any route and most metabolites are
excreted in the urine and feces within 24 to 48 hours.  In contrast to
other routes, oral exposure results in significant formation and
absorption of major metabolite 1-Phenyl-2-nitroethyl-1-sulfonic acid
(PNSA), and formation of PNSA is not due to microbial action in the gut.

This metabolism study in the rat is classified Acceptable –
Nonguideline.

5.0	Toxicity Endpoint Selection

Toxicological Doses and Endpoint Selection

5.1.1	Acute Reference Dose (aRfD) tc \l2 "1. Acute Reference Dose (aRfD)
 –all populations

Study Selected: 28-day Oral Toxicity in Rats

MRID No.: N/A – NTP study

Dose and Endpoint Proposed for Establishing aRfD:  NOAEL = 37 mg/kg/day
based on histopathology findings in the forestomach at 75 mg/kg/day
(LOAEL).

Uncertaninty Factor(s) Proposed for Consideration:	100 (10x interspecies
extrapolation, 10x intraspecies variation)

Comments about Study/Endpoint/Uncertaninty Factor(s):  Although a
developmental toxicity study in rats revealed a NOAEL of 75 mg/kg/day
based on increased incidence of excessive salivation along with a
reduced in mean weight gain during the treatment period and a
developmental NOAEL of 75 mg/kg/day based on a statistically significant
(p ≤ 0.01) decrease in mean fetal body weight and a slight increased
incidence of skeletal malformations (not statistically significant), a
28-day oral toxicity in rats with a NOAEL of 37 mg/kg/day is determined
to be more appropriate, given the fact of irritation characteristics of
bromonitrostyrene.  Further, this endpoint will provide adequate
protection for all populations including females 13-49 years old (i.e.,
pregnant workers).

Acute RfD (all populations) =       37 mg/kg    = 0.37 mg/kg

				    			     100

5.1.2	Chronic Reference Dose (cRfD) tc \l2 "1. Acute Reference Dose
(aRfD)  –all populations  tc \l2 "3. Chronic Reference Dose (cRfD)

Study Selected: 28-day Oral Toxicity in Rats

MRID No.: N/A – NTP study

Dose and Endpoint Proposed for Establishing aRfD:  NOAEL = 37 mg/kg/day
based on histopathology findings in the forestomach at 75 mg/kg/day
(LOAEL).

Uncertainty Factor(s):  1000 (10x inter-species extrapolation, 10x
intra-species variation, 10x database uncertainty)

Comments about Study/Endpoint/Uncertainty Factor:  A 10x database
uncertainty factor is applied because of no data on developmental study
in a non-rodent species and chronic studies.

Chronic RfD (all populations) =       37 mg/kg/day    = 0.037 mg/kg/day

          1000

5.1.3	Incidental Oral Exposure:  tc \l2 "4. Incidental Oral Exposure:
Short-Term (1-30 days)

Study Selected: 28-day Oral Toxicity in Rats

MRID No.: N/A – NTP study

Dose and Endpoint for Risk Assessment:  NOAEL = 37 mg/kg/day based on
histopathology findings in the forestomach at 75 mg/kg/day (LOAEL).

Uncertaninty Factor(s) Proposed for Consideration:	100 (10x interspecies
extrapolation, 10x intraspecies variation)

Comments about Study/Endpoint:  None.

5.1.3	Incidental Oral Exposure:  tc \l2 "4. Incidental Oral Exposure:
Intermediate-Term (1-6 months)

Study Selected: 28-day Oral Toxicity in Rats

MRID No.: N/A – NTP study

Dose and Endpoint for Risk Assessment:  NOAEL = 37 mg/kg/day based on
histopathology findings in the forestomach at 75 mg/kg/day (LOAEL).

Uncertaninty Factor(s) Proposed for Consideration:	300 (10x interspecies
extrapolation, 10x intraspecies variation, 3x database uncertainty)

Comments about Study/Endpoint/Uncertainty Factor:  A 3x database
uncertainty factor is applied because of no data on developmental study
in a non-rodent species.

Dermal Exposure:  Short-term (1-30 days) and Intermediate-Term (30
days-6months)

Type of Study Proposed:  21-Day Dermal Toxicity in Rabbits

MRID No.:  40830101

Dose and Endpoint Proposed for Consideration:  NOAEL = 50 mg/kg/day,
based on mortality in 2/5 females, reduced mean body weights in both
sexes, and statistically significant elevations in serum potassium
levels in both males and females at 100 mg/kg/day.

Uncertainty Factor(s) Proposed for Consideration:  100 (10x interspecies
extrapolation, 10x intraspecies variation).

Comments about Study/Endpoint/Uncertainty Factor(s):

5.1.5	Dermal Exposure:  Long-Term (>6months) tc \l2 "7. Dermal Exposure:
All Durations  Exposure

Type of Study Proposed:  21-Day Dermal Toxicity in Rabbits

MRID No.:  40830101

Dose and Endpoint for Risk Assessment:  NOAEL = 50 mg/kg/day, based on
mortality in 2/5 females, reduced mean body weights in both sexes, and
statistically significant elevations in serum potassium levels in both
males and females at 100 mg/kg/day.

Uncertainty Factor(s):  300 (10x interspecies extrapolation, 10x
intraspecies variation, 3x for use of subchronic endpoint for long-term
endpoint).

Comments about Study/Endpoint:  None.

5.1.6	Inhalation Exposure:  All Durations tc \l2 "10. Inhalation
Exposure: All Durations

Study Selected: 28-day Oral Toxicity in Rats

MRID No.: N/A – NTP study

Dose and Endpoint for Risk Assessment:  NOAEL = 37 mg/kg/day based on
histopathology findings in the forestomach at 75 mg/kg/day (LOAEL).

Uncertainty Factor(s):  1000 (10x inter-species extrapolation, 10x
intra-species variation, 10x route-to-route extrapolation)

Comments about Study/Endpoint:  An extra 10x is used because the current
inhalation endpoint is based on an oral NOAEL, and although the target
inhalation MOE is 1000, if the MOE is below 1000, the Agency may request
a confirmatory inhalation toxicity study.  In addition, a 100%
inhalation absorption value must be applied for route-to-route
extrapolation.

Dermal Absorption

Dermal Absorption Factor:    SEQ CHAPTER \h \r 1 Since a dermal endpoint
was selected from a dermal toxicity study, a dermal absorption factor is
not needed for bromonitrostyrene.

Classification of Carcinogenic Potential

There are no carcinogenicity data for bromonitrostyrene.  A
determination of carcinogenic potential cannot be made based on the
available data.  Metalworking cutting fluid use triggers the requirement
of carcinogenicity studies as described on the 1987 Antimicrobial Data
Call-In Notice.  In addition, the positive results of in vitro and in
vivo genetic toxicity studies warrant a carcinogenicity toxicity study.

The toxicological doses and endpoints selection are summarized below in
Table 3.

Table 3. Summary of Toxicological Doses and Endpoints for
Bromonitrostyrene

Exposure Scenario	Dose Used in

Risk Assessment

(mg/kg/day)	Target MOE, UF, Special FQPA SF, for Risk Assessment	Study
and

 Toxicological Effects

Dietary Risk Assessments

Acute Dietary

(all populations)

NOAEL = 37

UF = 100 (10x inter-species extrapolation, 10x intra-species variation)

28-day (Oral) Toxicity Study in Rats (NTP study)

LOAEL = 75 mg/kg/day based on histopathology findings in the forestomach

	aRfD = 0.37 mg/kg/day

Chronic Dietary

(all populations)

NOAEL= 37

UF = 1000 (10x inter-species extrapolation, 10x intra-species variation,
10x database uncertainty)

28-day (Oral) Toxicity Study in Rats (NTP study)

LOAEL = 75 mg/kg/day based on histopathology findings in the forestomach

	cRfD = 0.037 mg/kg/day

Non Dietary Risk Assessments

Incidental Oral

Short-Term

 (1-30days 	NOAEL=37

	Residential = 100 (10x inter-species extrapolation, 10x intra-species
variation)

Occupational = NA	28-day (Oral) Toxicity Study in Rats (NTP study)

LOAEL = 75 mg/kg/day based on histopathology findings in the forestomach

Incidental Oral

Intermediate-Term

(1-6 months)  	NOAEL=37

	Residential = 300 (10x inter-species extrapolation, 10x intra-species
variation and 3x database uncertainty)

Occupational = NA	28-day (Oral) Toxicity Study in Rats (NTP study)

LOAEL = 75 mg/kg/day based on histopathology findings in the forestomach

Dermal

Short-Term (1-30 days) and Intermediate-Term

(1-6 months)

	NOAEL (systemic) = 50 	MOE = 100 (10x inter-species extrapolation, 10x
intra-species variation)	21-Day (Dermal) Subchronic Toxicity Study in
Rabbits (MRID 40830101)

LOAEL = 100 mg/kg/day based on mortality in 2/5 females, reduced mean
body weights in both sexes, and statistically significant elevations in
serum potassium levels in both males and females.

Dermal

Long-Term

(> 6 months)	NOAEL (systemic) = 50 	MOE = 300 (10x inter-species
extrapolation, 10x intra-species variation, 3x for use of a subchronic
endpoint for the long-term endpoint) 	21-Day (Dermal) Subchronic
Toxicity Study in Rabbits (MRID 40830101)

LOAEL = 100 mg/kg/day based on mortality in 2/5 females, reduced mean
body weights in both sexes, and statistically significant elevations in
serum potassium levels in both males and females.

Inhalation

(All Durations)	NOAEL = 37 a	MOE = 1000b (10x inter-species
extrapolation, 10x intra-species variation, 10x route-to-route
extrapolation)   	28-day (Oral) Toxicity Study in Rats (NTP study)

LOAEL = 75 mg/kg/day based on histopathology findings in the forestomach

Cancer

(oral, dermal, inhalation)	No carcinogenicity data available for
bromonitrostyrene.

UF = uncertainty factor, NOAEL = no observed adverse effect level, LOAEL
= lowest observed adverse effect level, RfD = reference dose, MOE =
margin of exposure

a  A 100% inhalation absorption value is used for route-to-route
extrapolation.

b An extra 10x is used because the current inhalation endpoint is based
on an oral NOAEL, and although the       target inhalation MOE is 1000,
if the MOE is below 1000, the Agency may request a confirmatory
inhalation       toxicity study.

FQPA Considerations

6.1	Special Sensitivity to Infants and Children

The toxicology database for bromonitrostyrene with respect to assessing
sensitivity of infants and children is not complete.  There is only one
developmental toxicity study in rats available for this chemical.  There
are no data on developmental toxicity in a non-rodent species and no
data on reproductive toxicity.

	6.2	Developmental Toxicity Study Conclusions

In a developmental toxicity study (MRID 40728701), Giv 2-0820 (99.1%
ß-bromo-ß-nitrostyrene) was administered (as a suspension in corn oil)
to 24 or 25 mated female CDR  Sprague-Dawley derived rats/dose level by
gastric intubation at dose levels of 0 (vehicle only), 30, 75, and 150
mg/kg/day from days 6 through 15 of gestation.

There were no indications of any maternal toxicity at 30 mg/kg/day.  At
75 mg/kg/day there was an increased incidence of excessive salivation.
A further increased incidence of excessive salivation and additional
symptoms including moist rales, anogenital staining, a reduced mean
weight gain (21.2% below the control value, although not statistically
significant) in the treatment period occurred at 150 mg/kg/day.  In
addition, two dams died at this dose level only two days after dosage
was initiated.

Mean fetal body weights were significantly reduced in the high-dose (150
mg/kg/day) group, and were somewhat reduced at 75 mg/kg/day (not
statistically significant), with no indication of an effect on this
parameter at 30 mg/kg/day (mean body weights: controls: 3.67 g; 30
mg/kg/day: 3.69 g; 75 mg/kg/day: 3.53 g; 150 mg/kg/day: 3.35 g).  There
was no indication of any effect involving external or visceral
anomalies; the fetal (litter) incidences of skeletal malformations were
2/143 (2/22), 3/161 (1/24), 0/144 (0/24), and 8/137 (4/20) for the
controls, 30 mg/kg/day, 75 mg/kg/day and 150 mg/kg/day groups,
respectively.  The most common malformation was wavy ribs, seen in one
control fetus, three low-dose fetuses and four high-dose fetuses.

The maternal toxicity NOAEL is 75 mg/kg/day; the maternal LOAEL is 150
mg/kg/day (increased incidence of excessive salivation along with a
reduced [21.2% below the control value but not statistically
significant] in mean weight gain during the treatment period [6-15 days
of gestation]).

p ≤ 0.01] decrease in mean fetal body weight and a slight [not
statistically significant] increased incidence of skeletal
malformations).

A developmental toxicity study in non-rodents was not available.  This
is a deficiency.

	6.3	Reproductive Toxicity Study Conclusions

  SEQ CHAPTER \h \r 1 There are no data on the reproductive toxicity of
bromonitrostyrene.  For the current registered uses of this chemical,
this study is required and is considered a data gap in the absence of
the study.

	6.4	Pre-and/or Postnatal Toxicity

6.4.1	Determination of Susceptibility

  SEQ CHAPTER \h \r 1 There is no evidence for susceptibility to
bromonitrostyrene, but the data are limited to one developmental
toxicity study.  For this reason, extra uncertainty factors will be
employed to account for the lack of a complete database.

6.4.2	Degree of Concern Analysis and Residual Uncertainties

  SEQ CHAPTER \h \r 1 Uncertainties exist with respect to determination
of both developmental and reproductive effects of bromonitrostyrene, as
the data are limited to the one developmental toxicity study.  Lacks of
a reproductive toxicity study and a developmental toxicity study in a
non-rodent species raise the level of concern for adequately
characterizing potential susceptibility of bromonitrostyrene.

		6.4.3	Proposed Hazard-based Special FQPA Safety Factor(s)

It is decided that   SEQ CHAPTER \h \r 1   SEQ CHAPTER \h \r 1 no
special hazard-based safety factor under the FQPA is needed for
bromonitrostyrene based on its current registered use patterns.
Instead, additional database uncertainty factors will be used to take
into account the incompleteness of the database as well as regarding
infants and children’s susceptibility.

6.5	Recommendation for a Developmental Neurotoxicity Study

6.5.1	Evidence of Neurotoxicity

From the available repeated-dose toxicity studies, there was no evidence
of neurotoxicity of bromonitrostyrene.  It is concluded that there is no
concern for neurotoxicity resulting from exposure to bromonitrostyrene
based on the fact that no neurotoxicity findings in the available
studies.

  SEQ CHAPTER \h \r 1 It is further concluded that there is not a
concern for developmental neurotoxicity resulting from exposure to
bromonitrostyrene.7.0	REFERENCES

MRID 00150524	Fogleman, R. (1969) Short-term toxicity of GIV 0820 to
albino rats.  Affiliated Medical Enterprises, Inc., Princeton, New
Jersey.  Laboratory Contract No.:  20-284-9-69, October 30, 1969.
Unpublished

MRID 00150525	Fogleman, R. (1970) Thirty-day subacute oral toxicity in
rats on compound GIV 0820.  Affiliated Medical Enterprises, Inc.,
Princeton, New Jersey. Laboratory Contract No.: 120-285-9-69, February
17, 1970.  Unpublished.

MRID 40641309	Ivett, JL (1987) Mutagenicity Test on GIV 2-0820 in an In
Vitro Cytogenetic Assay Measuring Chromosomal Aberration Frequencies in
Chinese Hamster Ovary (CHO) Cell. Hazleton Laboratories, Inc.,
Kensington, MD; HLA Study No. 9725-0-437; report Date: April 1, 1987.
Unpublished.

MRID 40641310	Cifone, MA (1987) Mutagenicity Test on GIV 2-0820 in the
Rat Primary Hepatocyte Unscheduled DNA Snthesis Assay; Hazleton
Laboratories, Inc., Kensington, MD; HLA Study No. 9720-0-447; report
Date: August 6, 1987. Unpublished.

MRID 40691401	Timm A. (1987) Salmonella/Mammalina Microsome Mutagenicity
Test with (-brom-(-nitrostyrol: CCR, Cytotest Cell Research GmbH & Co.,
KG-6100, Darmstadt, Federal Republic of Germany; CCR Project #102205;
Reprot Date: July 8, 1987. Unpublished.

MRID 40691402	Schroeder, R. (1987) A Range-Finding Study to Evaluate the
Toxicity of Giv 2-0820 in the Pregnant Rat: Project No. 87-3162.
Unpublished study prepared by Bio/dynamics, Inc.

MRID 40728701	Schroeder, R. (1988) A Teratogenicity Study in Rats with
GIV 2-0820. Bio/Dynamics Inc., East Millstone, NJ 08875-2360. Project
No. 87-3163. 6 July 1988. Unpublished.

MRID 40830101	Auletta, CS. (1988) A 21-day Dermal Toxicity Study in
Rabbits with GIV 2-0820. Bio/Dynamics, Inc. Project No. 4541-87; July
28, 1988.  Unpublished.

MRID 41603501	Blaszcak, D. (1990) Acute Oral Toxicity Study in Rats with
Giv 2-0820: Final Report: Lab Project Number: 5723-89. Unpublished study
prepared by Bio/dynamics, Inc.

MRID 41603506	Blaszcak, D.L. (1990) Acute Oral Toxicity in Rats with BNS
25% AF: Final Report: Lab Project Number 5753-89.  Unpublished Study
prepared by Bio/dynamics., Inc.

MRID 41744601	Blaszcak, D. (1990) Primary Dermal Irritation Study in
Rabbits with BNS 25% AF: Lab Project Number: 5876-90.  Unpublished study
prepared by Bio/dynamics, Inc.

MRID 43452701	Hoffman, G. (1994) An Acute (4-Hour) Inhalation Toxicity
Study of BNS in the Rat via Nose-Only Exposure: Lab Project Number: 94
-5176. Unpublished study prepared by Pharmaco LSR Inc.

MRID 44178401	Blanset, D. (1996) Skin Corrosivity Evaluation of BNS 25%
AF in the Rabbit: Lab Project Number: 96-1498. Unpublished study
prepared by Huntingdon Life Sciences. 21 p.

MRID 44524506	Madarasz, A. (1997) Acute Dermal Toxicity Study in
Rabbits: GIV-GARD BNS 25% BA: Final Report: Lab Project No. 97-1653.
Unpublished study prepared by Huntingdon Life Sciences.

MRID 44524508	Madarasz, A. (1997) Primary Dermal Irritation Study in
Rabbits: GIV-GARD BNS 25% BA: Final Report: Lab Project Number: 97-1654.
Unpublished study prepared by Huntingdon Life Sciences. 18 p.

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24509	Madarasz, A. (1997) Primary Eye Irritation Study in Rabbits:
GIV-GARD BNS 25% BA: Final Report: Lab Project Number: 97-1655.
Unpublished study prepared by Huntingdon Life Sciences. 25 p.

MRID 44524510	Madarasz, A. (1997) Guinea Pig Maximization Test (Method
of Magnusson and Kligman): GIV-GARD BNS 25% BA: Final Report: Lab
Project Number: 97-1656. Unpublished study prepared by Huntingdon Life
Sciences. 33 p.

MRID 45094806	Hoffman, G. (1999) Guinea Pig Maximization Test (Method of
Magnusson and Kligmann): Spectrum RX4101: Final Report: Lab Project
Number: 98 -1866. Unpublished study prepared by Huntingdon Life
Sciences. 39 p.

MRID 46972603	Cifone, M. A. (2001) In vivo/in vitro unscheduled DNA
synthesis in rat primary hepatocyte cultures at two time points with a
dose rangefinding assay with (-brom-(-nitrostyrol. Covance Laboratories
Inc., Vienna, VA. Covance Study No.: 21569-0-494OECD, Dow Study No.:
001099, January 25, 2001. Unpublished.

MRID 47010001	Spencer, P.J., T.A. Hammond and D.J. Beuthin. (2001)
Evaluation of β-bromo-β-nitrostyrene in the mouse bone marrow
micronucleus test. Toxicology & Environmental Research and Consulting,
The Dow Chemical Company, Midland, MI. Laboratory Project Study ID.:
001150, January 16, 2001. Unpublished.

Bucher, J. (1994) NTP Technical Report on Toxicity Studies of
β-Bromo-β-nitrostyrene administered by gavage to F344 rats and B6C3F1
mice. Microbiological Associates, Inc. NTP Toxicity Report Series No.:
40, August, 1994. MRID # not assigned at this time. Published (NIH
Publication 94-3389).

Ingram, K. (2006)  Re: Bromonitrostyrene: A letter to the Agency for
cancellation of product labels, Slime-Trol RX-41 (74655-5), Slime-Trol
RX-45 (74655-8), Slime-Trol RX-52 (74655-13).  October 31, 2006.

MacGregor, J., C. Wehr, P. Heniks, et al. (1990). The in vivo
erythrocyte micronucleus test: Measurement at steady state increases
assay efficiency and permits integration with toxicity studies.
Fundamentals of Applied Toxicology. 14, 513-522.

Zeiger E., B. Anderson, S. Haworth S, et al. (1992) Salmonella
mutagenicity tests: V. Results from the testing of 311 chemicals.
Environmental Molecular Mutagenesis. 19 Suppl 21:2-141.

8.0  APPENDICES

Toxicity Profile Summary

Toxicity Profile Summary Tables

8.1.1  Acute Toxicity Table – See Section 4.1

8.1.2  Subchronic, Chronic and Other Toxicity Table

Table 4:  Subchronic, Chronic, and other Toxicity Profiles for
Bromonitrostyrene

Guideline Number/

Study Type/

Test Substance (% a.i.)	MRID Number (Year)/

Classification/ Doses	Results

870.3100

28-day Oral – Rat

Bromonitrostyrene

Purity: >99% (trans isomer)	NTP study (1994)

Acceptable – Non-guideline

0, 37, 75, 150, 300, or 600 mg/kg/day	NOAEL: 37 mg/kg/day (males) and 75
mg/kg/day (females)

LOAEL: 75 mg/kg/day (males) and 150 mg/kg/day (females), based on
histopathology findings in the forestomach.

870.3100

28-day Oral – Mouse

Bromonitrostyrene

Purity: >99% (trans isomer)	NTP study (1994)

Acceptable – Non-guideline

0, 37, 75, 150, 300, or 600 mg/kg/day	NOAEL: 150 mg/kg/day

LOAEL: 300 mg/kg/day based on microscopic pathology of the forestomach
and gallbladder.

870.3100

30-day Oral – Rat

Giv 0820

Purity: Not reported

Rang-finding – Rat

 Giv 0820

Purity: Not reported	150525 (1970)

Unacceptable

0, 50, 110, or 300 mg/kg/day (0, 500, 1000, 2500 ppm)

150524 (1969)

Unacceptable

0, 110, 300 or 370 mg/kg/day (0, 1000, 2500, 5000 ppm)	NOAEL: 300
mg/kg/day (2500 ppm)

LOAEL:  Not established (although increased kidney-body weight ratio in
the males were observed, no toxicity or histopathological changes were
noted).

NOAEL: 110 mg/kg/day (1000 ppm)

LOAEL: 300 mg/kg/day (2500 ppm) based on decreased food efficiency
ratios in both sexes.

870.3200

21-day Dermal - Rabbit

GIV 2-0820

Purity: 99.1%	40830101 (1988)

Acceptable - Guideline

0, 10, 50, or 100 mg/kg/day	Systemic Toxicity

NOEL: 50 mg/kg/day

LOEL: 100 mg/kg/day based on mortality in 2/5 females, reduced mean body
weights in both sexes, and statistically significant elevations in serum
potassium levels in both males and females at termination.

Dermal Toxicity

NOEL: ( 10 mg/kg/day (LDT) based on dermal irritation effects observed
at all dose levels.

870.3700

Developmental – Rat (a range-finding study)

Bromonitrostyrene

Purity: 99.1%	40691402 (1987)

Acceptable – Non-guideline

0, 30, 75, 150, 300, and 600 mg/kg/day

	At 300 mg/kg/day, 2/5 females were sacrificed moribund (gestation days
8 and 11), and at 600 mg/kg/day 5/5 females died on gestation days 7-10
(after receiving 1-4 doses of the test material).  During the treatment
period, mean body weight gains were similar in controls and the 30 and
75 mg/kg/day groups, but were reduced in the 150 mg/kg/day group (by
16.7%) and the 300 mg/kg/day group (by 31%).†ഠ

There was no indication of fetotoxicity (no ↑ number of late
resorption, no dead fetuses, no effect on mean fetal body weight) at
doses of up to 300 mg/kg/day at termination.

870.3700

Developmental - Rat

GIV 2-0820

Purity: 99.1%	40728701 (1988)

Acceptable - Guideline

0, 30, 75, or 150 mg/kg/day	Maternal Toxicity

NOAEL: 75 mg/kg/day

LOAEL: 150 mg/kg/day for increased incidence of excessive salivation
along with a reduced in mean weight gain (21.1% below the control value
but not statistically significant) during the treatment period (6-15
days of gestation).

Developmental Toxicity

NOAEL: 75 mg/kg/day

≤0.01) and a slight increased incidence of skeletal malformations,
mostly wavy ribs (not statistically significant).

870.5100

Salmonella typhimurium Reverse Mutation Test

(-brom-(-nitrostyrol

Purity: > 92%	40691401 (1987)

Partially Acceptable - Guideline

Without S9 activation:

0.01 to 3.33 µg/plate (TA 1535, TA 1537, TA 1538, and TA 98);

and

0.10 to 33.33 µg/plate (TA 100);

With S9 activation:

1.0 to 333.3 (g/plate (all strains)	Positive

(TA100 in the absence and presence of S9 mix)

870.5100

Salmonella typhimurium Reverse Mutation Test

(-brom-(-nitrostyrol

Purity: > 95%	NTP study  (1994)

Acceptable – Non-guideline

Without S9 activation: 0, 1, 3.3, 5, 10, 15, or 20 µg/plate (TA97,
TA98, and TA100)

and

0, 0.3, 1, 3.3, 10, or 20 µg/plate (TA1535)

With S9 activation (5% hamster or rat S9): 0, 1, 3.3, 10, 15, 20, 33, or
100 µg/plate (TA97, TA98, and TA100)

and

(10% hamster or rat S9): 0, 3.3, 10, 33, 100 or 200 µg/plate (TA97,
TA98, TA100, and TA1535)	Positive

(TA98 and TA100 in the absence of S9 mix)

In Vitro Mammalian Chromosome Aberration Test

GIV 2-0820                     Purity: 99.1%

	40641309 (1987)

Acceptable - Guideline

1.00 to 3.00 (g/mL (first assay, without S9 activation)
2.25 to 5.00 (g/mL (second assay, without S9 activation)   0.997 to 7.48
(g/mL (with S9 activation)	Positive

870.5395

In Vivo Mammalian Cytogenetics - Erythrocyte Micronucleus Assay

(-brom-(-nitrostyrol

Purity: > 99%	NTP study (1994)

Acceptable – Non-guideline

0, 37, 75, 150, 300 or 600 mg/kg/day in 5 mL/kg bw of corn oil	Positive

(significant increase in the frequency of micronucleated normochromatic
erythrocytes)

870.5395

In Vivo Mammalian Cytogenetics - Erythrocyte Micronucleus Assay

(-brom-(-nitrostyrol

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Acceptable – Guideline

0, 75, 150, or 300 mg/kg in 10 mL/kg bw of corn oil	Negative

870.5550

Unscheduled DNA Synthesis in Mammalian Cells in Culture - Rat

GIV 2-0820

Purity: 99.1%	40641310 (1987)

Acceptable – Guideline

0.25 to 25 µg/mL 	Negative

870.5550

Unscheduled DNA Synthesis in Mammalian Cells in Culture - Rat

(-brom-(-nitrostyrol

Purity: >99%	46972603 (2001)

Acceptable – Nonguideline

0, 350, 700 mg/kg in 20 mL/kg bw of corn oil	Negative

870.7485

Metabolism and

Pharmacokinetics – Rat

β-bromo-β-nitrostyrene

Purity: 98%	NTP study (1994)

Acceptable – Nonguideline

Oral (gavage): 1.0, 10, 100 mg/kg

IV: 9.1 mg/kg

Dermal: 0.1, 10, 100 mg/m2	Absorption:

Oral: 84%, 100%, 91% (1.0, 10, 100 mg/kg, respectively)

Dermal: 56%, 55%, 9% (1.0, 10, 100 mg/kg, respectively)

Excretion:

Oral: 49-57% (24 hr) and 50-66% (72 hr) in urine; 27-37% (24 hr) and
33-40% (72 hr) in feces

IV: 67% (12 hr) in urine and 11-13% (0-24 hr) in feces

Dermal: 0-24 hr: 45%
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Page   PAGE  4  of   NUMPAGES  37


[Federal Register Volume 79, Number 4 (Tuesday, January 7, 2014)]
[Proposed Rules]
[Pages 763-764]
[FR Doc No: 2014-00029]

========================================================================
Proposed Rules
                                                Federal Register
________________________________________________________________________

This section of the FEDERAL REGISTER contains notices to the public of
the proposed issuance of rules and regulations. The purpose of these
notices is to give interested persons an opportunity to participate in
the rule making prior to the adoption of the final rules.

========================================================================

Federal Register / Vol. 79, No. 4 / Tuesday, January 7, 2014 /
Proposed Rules

DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. FAA-2013-1009; Directorate Identifier 2013-NE-35-AD]
RIN 2120-AA64

Airworthiness Directives; Pratt & Whitney Canada Corp. Turboprop
Engines

AGENCY: Federal Aviation Administration (FAA), DOT.

ACTION: Notice of proposed rulemaking (NPRM).

-----------------------------------------------------------------------

SUMMARY: We propose to adopt a new airworthiness directive (AD) for
certain Pratt & Whitney Canada Corp. (P&WC) turboprop engines. This
proposed AD was prompted by in-service events involving the perforation
of engine cases as a result of the liberation of power turbine (PT)
blades and the fracture/displacement of the PT containment ring. This
proposed AD would require installing a reinforcement liner to the PT
containment ring and, for certain PT containment rings, adding
scallops. We are proposing this AD to prevent uncontained engine
failure and damage to the airplane.

DATES: We must receive comments on this proposed AD by March 10, 2014.

ADDRESSES: You may send comments by any of the following methods:
     Federal eRulemaking Portal: Go to http://www.regulations.gov and follow the instructions for sending your
comments electronically.
     Mail: Docket Management Facility, U.S. Department of
Transportation, 1200 New Jersey Avenue SE., West Building Ground Floor,
Room W12-140, Washington, DC 20590-0001.
     Hand Delivery: Deliver to Mail address above between 9
a.m. and 5 p.m., Monday through Friday, except Federal holidays.
     Fax:<PHONE_NUMBER>.
    For service information identified in this proposed AD, contact
Pratt & Whitney Canada Corp., 1000 Marie-Victorin, Longueuil, Quebec,
Canada, J4G 1A1; phone:<PHONE_NUMBER>; fax:<PHONE_NUMBER>; Internet:
www.pwc.ca. You may view this service information at the FAA, Engine &
Propeller Directorate, 12 New England Executive Park, Burlington, MA.
For information on the availability of this material at the FAA, call
781-238-7125.

Examining the AD Docket

    You may examine the AD docket on the Internet at http://www.regulations.gov by searching for and locating Docket No. FAA-2013-
1009; or in person at the Docket Operations office between 9 a.m. and 5
p.m., Monday through Friday, except Federal holidays. The AD docket
contains this proposed AD, the mandatory continuing airworthiness
information (MCAI), the regulatory evaluation, any comments received,
and other information. The street address for the Docket Operations
office (phone:<PHONE_NUMBER>) is the same as the Mail address provided
in the ADDRESSES section. Comments will be available in the AD docket
shortly after receipt.

FOR FURTHER INFORMATION CONTACT: Robert Green, Aerospace Engineer,
Engine Certification Office, FAA, Engine & Propeller Directorate, 12
New England Executive Park, Burlington, MA 01803; phone:<PHONE_NUMBER>;
fax:<PHONE_NUMBER>; email<EMAIL_ADDRESS>
SUPPLEMENTARY INFORMATION:

Comments Invited

    We invite you to send any written relevant data, views, or
arguments about this proposed AD. Send your comments to an address
listed under the ADDRESSES section. Include ``Docket No. FAA-2013-1009;
Directorate Identifier 2013-NE-35-AD'' at the beginning of your
comments. We specifically invite comments on the overall regulatory,
economic, environmental, and energy aspects of this proposed AD. We
will consider all comments received by the closing date and may amend
this proposed AD based on those comments.
    We will post all comments we receive, without change, to http://www.regulations.gov, including any personal information you provide. We
will also post a report summarizing each substantive verbal contact
with FAA personnel concerning this proposed AD. Using the search
function of the Web site, anyone can find and read the comments in any
of our dockets, including, if provided, the name of the individual who
sent the comment (or signed the comment on behalf of an association,
business, labor union, etc.). You may review the DOT's complete Privacy
Act Statement in the Federal Register published on April 11, 2000 (65
FR 19477-78).

Discussion

    Transport Canada Civil Aviation, which is the aviation authority
for Canada, has issued AD CF-2013-33R1, dated November 14, 2013
(referred to hereinafter as ``the MCAI''), to correct an unsafe
condition for the specified products. The MCAI states:

    There have been in-service events involving the perforation of
PT6A small series engine cases as a result of the loss of integrity
of Power Turbine (PT) Containment Rings under failure loads.
Perforation of engine cases has been seen to result from the
liberation of PT blades and from fracture/displacement of the PT
Containment Ring itself.

You may examine the MCAI in the AD docket on the Internet at http://www.regulations.gov by searching for and locating it in Docket No. FAA-
2013-1009.

Relevant Service Information

    P&WC has issued Service Bulletin (SB) No. PT6A-72-A1427, Revision
3, dated January 27, 2012. The SB describes procedures for reworking an
affected PT containment ring by installing a reinforcement liner and,
depending on the part number of the reworked ring, machining scallops
into the ring.

FAA's Determination and Requirements of This Proposed AD

    This product has been approved by the aviation authority of Canada,
and is approved for operation in the United States. Pursuant to our
bilateral agreement with Canada, they have notified us of the unsafe
condition described in the MCAI and service information referenced
above. We are proposing this AD because we evaluated all information
provided by Transport Canada Civil Aviation and determined the unsafe
condition exists and is likely to exist or develop on other products of
the same type design. This proposed AD would require installing a
reinforcement liner to the PT containment ring and, for

certain PT containment rings, adding scallops.

Costs of Compliance

    We estimate that this proposed AD affects 1,000 engines of U.S.
registry. We also estimate that it would take about 3 hours per engine
to comply with this proposed AD. The average labor rate is $85 per
hour. Required parts cost about $1,655 per engine. Based on these
figures, we estimate the cost of this proposed AD on U.S. operators to
be $1,910,000.

Authority for This Rulemaking

    Title 49 of the United States Code specifies the FAA's authority to
issue rules on aviation safety. Subtitle I, section 106, describes the
authority of the FAA Administrator. ``Subtitle VII: Aviation
Programs,'' describes in more detail the scope of the Agency's
authority.
    We are issuing this rulemaking under the authority described in
``Subtitle VII, Part A, Subpart III, Section 44701: General
requirements.'' Under that section, Congress charges the FAA with
promoting safe flight of civil aircraft in air commerce by prescribing
regulations for practices, methods, and procedures the Administrator
finds necessary for safety in air commerce. This regulation is within
the scope of that authority because it addresses an unsafe condition
that is likely to exist or develop on products identified in this
rulemaking action.

Regulatory Findings

    We determined that this proposed AD would not have federalism
implications under Executive Order 13132. This proposed AD would not
have a substantial direct effect on the States, on the relationship
between the national Government and the States, or on the distribution
of power and responsibilities among the various levels of government.
    For the reasons discussed above, I certify this proposed
regulation:
    (1) Is not a ``significant regulatory action'' under Executive
Order 12866,
    (2) Is not a ``significant rule'' under the DOT Regulatory Policies
and Procedures (44 FR 11034, February 26, 1979),
    (3) Will not affect intrastate aviation in Alaska to the extent
that it justifies making a regulatory distinction, and
    (4) Will not have a significant economic impact, positive or
negative, on a substantial number of small entities under the criteria
of the Regulatory Flexibility Act.
    We prepared a regulatory evaluation of the estimated costs to
comply with this proposed AD and placed it in the AD docket.

List of Subjects in 14 CFR Part 39

    Air transportation, Aircraft, Aviation safety, Incorporation by
reference, Safety.

The Proposed Amendment

    Accordingly, under the authority delegated to me by the
Administrator, the FAA proposes to amend 14 CFR part 39 as follows:

PART 39--AIRWORTHINESS DIRECTIVES

0
1. The authority citation for part 39 continues to read as follows:

    Authority: 49 U.S.C. 106(g), 40113, 44701.

Sec.  39.13  [Amended]

0
2. The FAA amends Sec.  39.13 by adding the following new airworthiness
directive (AD):

Pratt & Whitney Canada Corp.: Docket No. FAA-2013-1009; Directorate
Identifier 2013-NE-35-AD.

(a) Comments Due Date

    We must receive comments by March 10, 2014.

(b) Affected ADs

    None.

(c) Applicability

    This AD applies to Pratt & Whitney Canada Corp. (P&WC) turboprop
engines as follows: all model PT6A-20, PT6A-20A, PT6A-20B, PT6A-25,
PT6A-28, PT6A-34B, PT6A-36, and PT6A-135 engines; model PT6A-21
engines, serial number (S/N) PCE-25361 and earlier; model PT6A-25A
engines, S/N PCE-48757 and earlier; model PT6A-25C engines, S/N PCE-
26258 and earlier; model PT6A-27 engines, S/N PCE-42523 and earlier
as well as all engines converted to PT6A-27; model PT6A-34 engines,
S/N PCE-57303 and earlier as well as all engines converted to PT6A-
34; model PT6A-34AG engines, S/N PCE-57312 and earlier as well as
all engines converted to PT6A-34AG; model PT6A-114 engines, S/N PCE-
17218 and earlier; and model PT6A-135A engines, S/N PCE-35089 and
earlier.

(d) Reason

    This AD was prompted by in-service events involving the
perforation of engine cases as a result of the liberation of power
turbine (PT) blades and the fracture/displacement of the PT
containment ring. We are issuing this AD to prevent uncontained
engine failure and damage to the airplane.

(e) Actions and Compliance

    (1) Comply with this AD within the compliance times specified,
unless already done.
    (2) Within 24 months after the effective date of this AD, modify
the existing PT containment ring. Use paragraph 3., Accomplishment
Instructions, of P&WC Service Bulletin (SB) No. PT6A-72-A1427,
Revision 3, dated January 27, 2012, to make the modification.

(f) Credit for Previous Actions

    If you modified the PT containment ring before the effective
date of this AD using P&WC SB No. PT6A-72-A1427, Revision 3, dated
January 27, 2012, or earlier versions, you have met the requirements
of this AD.

(g) Alternative Methods of Compliance (AMOCs)

    The Manager, Engine Certification Office, FAA, may approve AMOCs
to this AD. Use the procedures found in 14 CFR 39.19 to make your
request.

(h) Related Information

    (1) For more information about this AD, contact Robert Green,
Aerospace Engineer, Engine Certification Office, FAA, Engine &
Propeller Directorate, 12 New England Executive Park, Burlington, MA
01803; phone:<PHONE_NUMBER>; fax:<PHONE_NUMBER>; email:
<EMAIL_ADDRESS>    (2) Refer to MCAI Transport Canada Civil Aviation AD CF-2013-
33R1, dated November 14, 2013, for more information. You may examine
the MCAI in the AD docket on the Internet at http://www.regulations.gov by searching for and locating it in Docket No.
FAA-2013-1009.
    (3) P&WC SB No. PT6A-72-A1427, Revision 3, dated January 27,
2012, pertains to the subject of this AD and can be obtained from
P&WC, using the contact information in paragraph (h)(4) of this AD.
    (4) For service information identified in this AD, contact Pratt
& Whitney Canada Corp., 1000 Marie-Victorin, Longueuil, Quebec,
Canada, J4G 1A1; phone:<PHONE_NUMBER>; fax:<PHONE_NUMBER>; Internet:
www.pwc.ca.
    (5) You may view this service information at the FAA, Engine &
Propeller Directorate, 12 New England Executive Park, Burlington,
MA. For information on the availability of this material at the FAA,
call<PHONE_NUMBER>.

    Issued in Burlington, Massachusetts, on January 2, 2014.
Colleen M. D'Alessandro,
Assistant Directorate Manager, Engine & Propeller Directorate, Aircraft
Certification Service.
[FR Doc. 2014-00029 Filed 1-6-14; 8:45 am]
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