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Description of key information

Oral: ALD; rat; gavage; reliability = 2; CLASSIFIED: Cat 4.
Dermal: ALD; rabbit; reliability = 2; CLASSIFIED: Cat 4. [CAS# 95-54-5]
Inhalation: 4-hr LC50; rat; reliability = 2; CLASSIFIED: Cat 4.
Dermal ALD = 1500 mg/kg

Key value for chemical safety assessment

Acute toxicity: via oral route

Link to relevant study records
Reference
Endpoint:
acute toxicity: oral
Type of information:
experimental study
Adequacy of study:
key study
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
comparable to guideline study with acceptable restrictions
Qualifier:
equivalent or similar to
Guideline:
OECD Guideline 401 (Acute Oral Toxicity)
Deviations:
yes
Remarks:
Only one animal per dose level.
GLP compliance:
not specified
Test type:
standard acute method
Species:
rat
Strain:
other: Crl:CD BR
Sex:
male
Details on test animals and environmental conditions:
TEST ANIMALS
- Source: Charles River Laboratories, Raleigh, North Carolina
- Age at study initiation: 7 weeks
- Weight at study initiation: 239-297 g
- Housing: individually in suspended stainless steel, wire-mesh cages
- Diet (e.g. ad libitum): Purina Rodent Chow #5002 ad libitum
- Water (e.g. ad libitum): ad libitum
- Acclimation period: one week

ENVIRONMENTAL CONDITIONS
- Temperature (°C): 23± 1°C
- Humidity (%): 50% ± 10%
- Photoperiod (hrs dark / hrs light): 12/12

IN-LIFE DATES: From: 7/18/95 To: 8/10/95
Route of administration:
oral: gavage
Vehicle:
water
Details on oral exposure:
The test substance was suspended in deionized water and administered to 1 rat per dose rate by intragastric intubation. Rats were administered doses ranging from 130 to 670 mg/kg-bw in increments of approximately 50%. Additionally, 1 rat was dosed at 2300 mg/kg. The dosing day was test day one; post exposure day 14 was test day 15.
Doses:
Dosage (mg/kg): 130, 200, 300, 450, 670, 2300
Dose vol (mL): 0.18, 0.30, 0.42, 0.61, 0.80, 2.8
Suspension (mg/L): 200, 200, 200, 200, 200, 200
No. of animals per sex per dose:
1 rat per dose level
Control animals:
not specified
Details on study design:
- Duration of observation period following administration: 14 days
- Frequency of observations and weighing: Following administration the rats were observed for clinical signs of toxicity. All surviving rats were weighed and observed daily until toxicity subsided up to test day 15.
- Necropsy of survivors performed: no
Sex:
male
Dose descriptor:
other: Approximate Lethal Dose (ALD)
Effect level:
450 mg/kg bw
Mortality:
The lowest dose of the test substance which resulted in death of a test animal was 450 mg/kg. The rat dosed at 450 mg/kg was found dead by day 2. Deaths also occurred in rats treated at 670 and 2300 mg/kg. The rat treated at 670 mg/kg was found dead 2 days after dosing. The rat treated at 2300 mg/kg was found dead 1 day after dosing.
Clinical signs:
NONLETHAL DOSES: Lethargy was observed in the rats treated at 130, 200, and 300 mg/kg approximately 1 hour after dosing. Ruffled fur was observed in rats treated at 200 or 300 mg/kg up to 3 days.

LETHAL DOSES: Lethargy was observed in the rats treated at 450 or 2300 mg/kg, and lethargy and partially closed eyes were observed in the rat treated at 670 mg/kg approximately 1 hour after dosing.
Body weight:
A weight loss of approximately 8% of initial body weight was observed in the 200 mg/kg treated rat 1 day after dosing. A combined total of approximately 13% of initial body weight was observed in the 300 mg/kg treated rats by 3 days after dosing. The rat dosed at 450 mg/kg exhibited a weight loss of approximately 5% of initial body weight one day after dosing.
Gross pathology:
Pathological examinations were not performed.

Dosage (mg/kg)

Dose Volume (mL)

Suspension (mg/mL)

Initial body weight (g)

Mortality

130

0.18

200

272

No

200

0.30

200

297

No

300

0.42

200

282

No

450

0.61

200

273

Yes

670

0.80

200

239

Yes

2300

2.8

200

240

Yes

Interpretation of results:
Category 4 based on GHS criteria
Conclusions:
Under the conditions of this study, the ALD for the test substance was 450 mg/kg of body weight.
Executive summary:

The test substance was administered as a single oral dose by intragastric intubation to male rats. Rats were found dead up to 2 days after dosing. Clinical signs of toxicity were observed in lethally and nonlethally dosed animals. Under the conditions of this test, the ALD was 450 mg/kg of body weight.

Endpoint conclusion
Endpoint conclusion:
adverse effect observed
Dose descriptor:
discriminating dose
Value:
450 mg/kg bw

Acute toxicity: via inhalation route

Link to relevant study records
Reference
Endpoint:
acute toxicity: inhalation
Type of information:
experimental study
Adequacy of study:
key study
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
comparable to guideline study with acceptable restrictions
Qualifier:
equivalent or similar to
Guideline:
OECD Guideline 403 (Acute Inhalation Toxicity)
Deviations:
yes
Remarks:
partical size distribution not monitored; temperature, humidity, and pressure in chambers not reported
GLP compliance:
not specified
Test type:
standard acute method
Species:
rat
Strain:
other: Crl:CD
Sex:
male
Details on test animals and environmental conditions:
TEST ANIMALS
-Age at study initiation: 7-8 weeks
- Weight at study initiation: 236 - 278 grams
- Fasting period before study: not reported
- Housing: in pairs in 8"x8"x14" stainless steel cages
- Diet (e.g., ad libitum): ad libitum
- Water (e.g., ad libitum): ad libitum
- Acclimation period: 1 week

ENVIRONMENTAL CONDITIONS
-Temperature (ºC): not reported
- Humidity (%): not reported
- Air changes (per hr): not reported
- Photoperiod (hrs dark / hrs light): not reported
Route of administration:
inhalation: aerosol
Type of inhalation exposure:
nose only
Vehicle:
other: Nitrogen
Details on inhalation exposure:
Animals were exposed nose-only for single 4-hour periods to atmospheres containing MPD.
Generation: The test material was heated (146-188 ºC) in a round bottom flask. Heated nitrogen (52-75 ºC) was blown through the flask, sweeping MPD vapors into a dilution air stream. Prior to chamber entry, oxygen was added to this mixture to assure a final chamber O2 concentration >20%.
Analytical verification of test atmosphere concentrations:
yes
Remarks:
Test atmospheres were sampled by drawing chamber atmosphere through a fritted glass impinger containing methanol as the trapping solvent. Samples were analyzed on a Hewlett-Packard 5700A Gas Chromotograph equipped with a flame ionization detector.
Duration of exposure:
4 h
Concentrations:
Mean: 0.72, 2.0, 3.2, 3.9 mg/L
No. of animals per sex per dose:
10
Control animals:
not specified
Details on study design:
During exposure all rats were observed, clinical signs noted, and chamber oxygen content and temperature monitored. Following exposure, all surviving rats were weighed and observed for 14 days.
Sex:
male
Dose descriptor:
LC50
Effect level:
3.2 mg/L air (analytical)
95% CL:
> 2.6 - < 4.1
Exp. duration:
4 h
Sex:
male
Dose descriptor:
other: LOAEL
Effect level:
0.72 mg/L air
Exp. duration:
4 h
Remarks on result:
other: At all concentrations, rats exhibited red ocular and nasal discharge.
Mortality:
Deaths occurred 1-7 days post exposure.
Clinical signs:
other: At all concentrations, rats exhibited red ocular and nasal discharge. Rats at all concentrations showed hair loss and wet perineum. Lung noise, brown stained fur, pallor, and tremors were observed at concentrations ≥ 2.0 mg/L. Labored breathing, dry re
Body weight:
At all concentrations, rats exhibited moderate to severe weight loss for 1-3 days followed by weight gain.
Other findings:
Upon contact with the cool dilution air, the test substance's vapors condensed into an aerosol. The resulting atmosphere was visible to the unaided eye. Chamber temperature was ≤ 31 ºC and oxygen content was ≥ 20% for all exposures.
Interpretation of results:
Category 4 based on GHS criteria
Conclusions:
4-hour LC50 = 3.2 mg/L
Executive summary:

An inhalation Median Lethal Concentration for the test substance was determined in male Crl:CD®rats given single 4 -hour exposures. The calculated LC50 is 3.2 mg/L with 95% confidence limits of 2.6 and 4.1 mg/L.

Endpoint conclusion
Endpoint conclusion:
adverse effect observed
Dose descriptor:
LC50
Value:
3 200 mg/m³

Acute toxicity: via dermal route

Link to relevant study records
Reference
Endpoint:
acute toxicity: dermal
Type of information:
read-across from supporting substance (structural analogue or surrogate)
Adequacy of study:
key study
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
comparable to guideline study with acceptable restrictions
Justification for type of information:
Additional documentation, provided within the IUCLID Assessment Reports (Section 13), supports the read-across approach.
Reason / purpose:
read-across: supporting information
Qualifier:
equivalent or similar to
Guideline:
OECD Guideline 402 (Acute Dermal Toxicity)
Deviations:
yes
Remarks:
only 1 animal per dose level, only one sex tested, necropsy on only 7 of the 9 animals conducted
GLP compliance:
not specified
Species:
rabbit
Strain:
other: albino
Sex:
male
Details on test animals and environmental conditions:
TEST ANIMALS
- Age at study initiation: Not reported
- Weight at study initiation: 2.5-3.0 g
- Fasting period before study: None
- Housing: Not reported
- Diet (e.g. ad libitum): Not reported
- Water (e.g. ad libitum): Not reported
- Acclimation period: Not reported

ENVIRONMENTAL CONDITIONS
- Temperature (°C): Not reported
- Humidity (%): Not reported
- Air changes (per hr): Not reported
- Photoperiod (hrs dark / hrs light): Not reported
Type of coverage:
occlusive
Vehicle:
other: hydrophilic ointment or polypropylene glycol
Details on dermal exposure:
TEST SITE: Rabbits were clipped at the trunk and fitted with collars.

REMOVAL OF TEST SUBSTANCE
- Washing (if done): After 24 hours contact, wrappings were removed and the treated areas were washed with water and dried.

TEST MATERIAL
- For solids, paste formed: Yes; material suspended in polypropylene glycol and applied through a single layer of gauze wrapped around the clipped trunk. For higher doses, a 50% paste of the material in hydrophilic ointment, U.S.P., was applied directly to the clipped skin without gauze. After application, all rabbits were then wrapped with impervious film, gauze, and elastic bandage.



Duration of exposure:
24 hours
Doses:
450, 670, 1000, 1500 (in polypropylene glycol), 1500, 2250 (yellow brown paste), 2250 (orange paste), 7500 and 11000 mg/kg
No. of animals per sex per dose:
one
Control animals:
no
Details on study design:
Animals were observed for 14 days before sacrifice. Necropsies were done on 7 of the 9 animals treated, and major tissues of 6 rabbits were saved for histopathological examination. No-necropsy rabbits: dosed at 11000 mg/kg and at 1500 mg/kg of the test substance in hydrophilic ointment; necropsy only - rabbit dosed at 1500 mg/kg of the test substance in polypropylene glycol.

Tissues examined included kidney, liver, trachea, lung, brain, testes, bone marrow, spleen, thymus, gastrointestinal tract and skin.
Sex:
male
Dose descriptor:
other: Approximate Lethal Dose (ALD)
Effect level:
1 500 mg/kg bw
Mortality:
Dose Level Mortality Ratio
(mg/kg)

450 (in 50% H.O.): 0/1
670 (in 50% H.O.): 0/1
1000 (in 50% H.O.): 0/1
1500 (in 15% DMP): 0/1
1500 (in 50% H.O.): 1/1
2250 (in 50% H.O.)
yellow brown paste: 0/1
2250 (in 50% H.O.)
orange paste: 1/1
7500 (in 50% H.O.): 1/1
11,000 (in 50% H.O.): 1/1
Clinical signs:
Clinical signs of toxicity observed included hematuria and abnormally dark urine, hyperemic eyelids, salivation, and debility.

Local signs: Irritation in most cases was at least partially obscured by residual dye. However, the rabbit dosed at 1000 mg/kg showed initial erythema and edema followed by desquamation. Initial erythema was noted at dose levels above 450 mg/kg.
Body weight:
2250 mg/kg (yellow brown paste): significant weight loss through 14 days
2250 mg/kg (orange paste): weight loss slight at 1 day, severe at 2 days
Gross pathology:
The following pathologic changes were observed at lethal doses:
Bladder - distended with red-tinged urine (gross exam)
Kidney - congestion (gross exam), inflammation and papillary necrosis (7500 mg/kg)
Liver - necrosis (2250 mg/kg)
Spleen - atrophy of lymphoid elements
Skin - necrosis of epithelium of deeper portions of hair follicles
Bone marrow - generalized necrosis
Thymus - lymphocytolysis
Small intestine - degeneration

The following pathologic changes were observed at non-lethal doses:
Kidney - papillary necrosis (2250 mg/kg)
Thymus - lymphoid atrophy at doses above 450 mg/kg
Bone marrow - generalized necrosis (2250 and 1000 mg/kg with regenerative response at 1000 mg/kg)
Interpretation of results:
Category 4 based on GHS criteria
Conclusions:
Dermal ALD = 1500 mg/kg
Executive summary:

The Approximate Lethal Dose (ALD) was 1500 mg/kg for rabbits when the test material was administered as 50% paste in hydrophilic ointment, U.S.P. Clinical signs of toxicity included hematuria and abnormally dark urine, hyperemic eyelids, salivation, and debility. Pathologic examination was done in most cases and showed frequent tissue changes in kidney, liver, bone marrow, lymphoid tissue, small intestine and skin. Local reaction was frequently obscured by the color of the test material; however, temporary moderate to mild irritation from occluded 24 hour contact was sometimes noted. In general, the orange-brown fraction appeared to be more toxic than the yellow-brown fraction in the skin absorption test.

Endpoint conclusion
Endpoint conclusion:
adverse effect observed
Dose descriptor:
discriminating dose
Value:
1 500 mg/kg bw

Additional information

The substance has a rat ALD value of 450 mg/kg, and a rat 4 -hour LC50 value of 3.2 mg/L (3200 mg/m3). In the acute inhalation toxicity test, rats exhibited red ocular and nasal discharge at all concentrations tested (LOAEL = 0.72 mg/L (720 mg/m3)). The structurally similar substance, o-phenylenediamine (CAS 95-54-5), was used as a surrogate for acute dermal data. o-Phenylenediamine has a rabbit ALD value of 1500 mg/kg.

Justification for classification or non-classification

Based on the rat 4-hour LC50 of 3.2 mg/L (3200 mg/m3), the rat oral ALD value of 450 mg/kg, and the rabbit dermal ALD value of 1500 mg/kg, the test substance is classified as Cat 4 (harmful if swallowed) for acute oral, Cat 4 (harmful in contact with skin) for acute dermal, and Cat 4 (harmful if inhaled) for acute inhalation according to the EU Classification, Labelling and Packaging of Substances and Mixtures (CLP) Regulation (EC) No. 1272/2008. Although, this classification deviates from the harmonized classification, the harmonized classification will be adhered as it is stricter.