Reference type

Author

Year

Title

Bibliographic source

Testing laboratory

Report no.

Owner company

Company study no.

Report date

publication

MHLW

2011

Twenty-eight-day Repeat Dose Oral Toxicity Test of 2-Nitro-p-cresol in Rats

available in the web of Japan Existing Chemical Data Base (JECDB) at http://dra4.nihs.go.jp/mhlw_data/jsp/SearchPageENG.jsp

Research institute for animal science in biochemistry and toxicology (RIAS)

data published

subacute

Qualifier

Guideline

Deviations

according to

other guideline: other guideline: Guideline for 28-Day Repeated Dose Toxicity Test in Mammalian Species (Chemical Substances Control Law of Japan)

equivalent or similar to

OECD Guideline 407 (Repeated Dose 28-Day Oral Toxicity in Rodents)

yes

yes

- Name of test material (as cited in study report): 2-Nitro-p-cresol
- Analytical purity: 99.8%
- Lot No.: FBR01
- Storage condition of test material: at a cold (temperature 2-6 ℃) and dark place, with airtight stopper.
- Stability under test conditions: The stability of test material was identified by analysis of the remainder.

rat

other: Crl:CD(SD)

male/female

TEST ANIMALS
- Source: Charles River Japan, Inc.
- Age at study initiation: 5 weeks old
- Weight at study initiation: male 161 g (146-173 g), female 144 g (130-154 g)
- Housing: Animals were individually housed in a metallic cage with wire mesh bottoms
- Diet: Solid feed (MR stock: Nosan Corporation) was given ad libitum.
- Water: Tap water was given ad libitum.
- Acclimation and quarantine period:7-8 days

ENVIRONMENTAL CONDITIONS
- Temperature (°C): 22±3 (actual temperature: 22.0-22.6 ℃)
- Humidity (%): 55±10% (actual humidity: 55-62%)
- Air changes (per hr): 10-15
- Photoperiod (hrs dark / hrs light): 12 hr dark/12 hr light (light: 7:00~19:00)

oral: gavage

olive oil

yes

28 days

once a day

0, 15, 60, 250, 1000 mg/kg bw/day

Basis

actual ingested

10/sex (0, 1000 mg/kg bw/day)
5/sex (15, 60, 250 mg/kg bw/day)

yes, concurrent vehicle

- Dose selection rationale: Doses in this test were set based on the results of the following study: 14-day repeated dose oral toxicity test (Crl:CD(SD) rats, doses: 0 (olive oil), 10, 30, 100, 250, 500 or 1000 mg/kg bw/day). At 500 mg/kg/day and higher, sedation and salivation, and tendency of urine oxidation were observed in both sexes. At 1000 mg/kg/day, anemia and changes in liver functions were observed. At 250 mg/kg/day and higher, an increasing tendency on the liver weight was observed in both sexes. On the basis of these effects, a dose level of 1000 mg/kg was selected as the maximum dose expecting to induce the toxic changes, and then dose levels of 250, 60 and 15 mg/kg bw/day were selected, in accordance with a common ratio of approximately 4.

- Rationale for animal assignment (if not random): Body weight-balanced randomization
- Post-exposure recovery period in satellite groups: 14 days

CLINICAL OBSERVATIONS: Yes
- Time schedule: every day during the administration (4 times a day) and recovery periods (at least once a day)

DETAILED CLINICAL OBSERVATIONS: Yes
The functional observational battery testing (FOB) was performed on all animals. Among the measures in the FOB, detailed clinical observations were made before the initiation of dosing. Thereafter, detailed clinical observations were made once a week in dosing and recovery periods.
Sensory motor reflexes, forelimb and hindlimb grip strengths, and motor activity were measured on week 4 of administration period (main/recovery group animals) and week 2 of recovery period (recovery group animals).

BODY WEIGHT: Yes
- Time schedule for examinations: Before administration (on days 1, 7, 14, 21 and 28 of the administration period, days 7 and 14 of the recovery period) and the necropsy days after completion of every period.

FOOD CONSUMPTION AND COMPOUND INTAKE (if feeding study):
- Food consumption: Yes. Once a week for 24-h (males: on days 5, 12, 19 and 26 of the administration period and days 5 and 12 of the recovery period. females: on days 4, 11, 18 and 25 of the administration period and days 4 and 11 of the recovery period)

OPHTHALMOSCOPIC EXAMINATION: No

HAEMATOLOGY: Yes
- Time schedule for collection of blood: the after completion of the administration and recovery periods
- Anaesthetic used for blood collection: ether
- Animals fasted: Yes (overnight)
- How many animals: all animals

CLINICAL CHEMISTRY: Yes
- Time schedule for collection of blood: the day after completion of the administration and recovery periods
- Anaesthetic used for blood collection: ether
- Animals fasted: Yes (overnight)
- How many animals: all animals

URINALYSIS: Yes
- Time schedule for collection of urine: on weeks 4 of the administration period and weeks 2 of the recovery period.
- Metabolism cages used for collection of urine: Yes

NEUROBEHAVIOURAL EXAMINATION: No

GROSS PATHOLOGY: Yes

ORGAN WEIBHT: Yes [brain, pituitary gland, thyroid, adrenal, spleen, heart, liver, kidney, thymus, testis, epididymis, ovary]

HISTOPATHOLOGY: Yes [brain (cerebrum, cerebellum and medulla oblongata), pituitary gland, spinal cord (cervical, thoracical, lumber), thymus, thyroid (including parathyroid), adrenal glands, spleen, heart, stomach, liver, duodenum, jejunum, ileum (including Peyer's patches), cecum, colon, rectal, mesenteric lymph nodes, submandibular lymph nodes, trachea, lung, kidney, bladder, testis, epididymis, prostate, seminal vesicles, ovary, uterus, vagina, eye, bone marrow (femur) and the sciatic nerve. (see tables in the study report.)

As for parametric data (grip strength, locomotor activity, body weight, body weight gain, food consumption, hematology and clinical chemistry data, organ weights), the values of means and standard deviations were calculated per group. When more than three groups exist in the test group, Bartlett test for variance was done, and if the variance was homogenous, ANOVA was applied. If the variance was not homogenous or data was non-parametric (differential WBC percentage, urinalysis data), Kruskal-Wallis rank sum test was used. Consequently, if the result was significant, Dunnett multiple comparison or Dunnett-typed method was used for detection of statistical significance against control group. When the number of the test group was two, F-test was used as for parametric data. Then, student's t-test or Aspin-Welch's t-test was applied depending on the result of homogeneity of variance. While, as for non-parametric data, Man-Whitney's U-test was applied. Furthermore, as for categorized data (incidence of abnormal findings in clinical observation, detailed observation, sensory functional examination, necropsy and histopathology), Fischer's exact test was used. In any tests, level of significance was set at 5%.

Endpoint

Effect level

Based on

Sex

Basis for effect level / Remarks

NOAEL

60 mg/kg bw/day (actual dose received)

test mat.

male/female

At 250 mg/kg bw/day and higher, sedation and ptosis were observed in both sexes. Increase in the liver weight was observed at 250 mg/kg bw/day and higher in females and at 1,000 mg/kg bw/day in males. Histopathological examinations revealed hypertrophy of hepatocytes at 250 mg/kg bw/day and higher in females.

yes (see Details on results)

no effects

no effects

yes (see Details on results)

yes (see Details on results)

yes (see Details on results)

no effects (see Details on results)

yes (see Details on results)

yes (see Details on results)

yes (see Details on results)

CLINICAL SIGNS AND MORTALITY
At 250 mg/kg bw/day and higher, sedation and ptosis were observed in both sexes.
Transient salivation was observed in both sexes at 1,000 mg/kg bw/day. Soiled fur in one female and reddish tear in one male were observed at 1,000 mg/kg bw/day.

NEUROBEHAVIOUR
Clinical signs in detailed observation: No effects.
Sensory/reflex function test: No effects.
Grip strength: In the recovery period, high value of hindlimb strength in males and low value of forelimb strength in female were observed. (These were within background date.)
Motor activity: No effects.

BODY WEIGHT AND WEIGHT GAIN: No effects.

FOOD CONSUMPTION: No toxicological effects.

HAEMATOLOGY
At 1,000 mg/kg bw/day, low values of Hb, Ht and MCHC, and high values of Ret were observed in males and females, and high value of APTT was observed in females. At the end of recovery period, high values of MCV and MCH, and low value of MCHC were observed in males.

CLINICAL CHEMISTRY
At 1,000 mg/kg bw/day, high values of Alb, A/G, T-Cho, and K in males, and high values of γ-GTP and T-Bil in females were observed. At the end of recovery period, high value of Na was observed in males.

URINALYSIS
Pale yellow color was observed at 250 mg/kg bw/day and higher in males and females. At 1,000 mg/kg bw/day, low value of pH were observed in males and females. In the recovery period, low value of specific gravity was observed in males.

ORGAN WEIGHTS
At 250 mg/kg bw/day and higher, sedation and ptosis were observed in both sexes. Increase in the liver weight was observed at 250 mg/kg bw/day and higher in females and at 1,000 mg/kg bw/day in males. Furthermore, increases in the kidney weight in males and spleen weight in both sexes were observed at 1,000 mg/kg bw/day.

GROSS PATHOLOGY
At 1,000 mg/kg bw/day, blackish color of the spleen was observed in males and females at the ends of administration and recovery periods.

HISTOPATHOLOGY: NON-NEOPLASTIC
Histopathological examinations revealed hyperostosis metaphysis of the femur in females at 200 mg/kg bw/day. Furthermore, at 1,000 mg/kg bw/day, hyperkeratosis of the mucosal epithelium in the forestomach, grade enhancement of regeneration of the tubular epithelium, dilatation of the renal tubules in the cortex, and cyst-like extension of the collecting duct in the kidney, and hyperostosis metaphysis of the femur were observed in both sexes. Additionally in males at 1,000 mg/kg bw/day, degeneration of nerve fibers in the sciatic nerve and atrophy of muscle fibers in the skeletal muscle were observed. And in females at 1,000 mg/kg bw/day, squamous cell hyperplasia of the boundary edge in the stomach was observed. These changes tended to resolve after the recovery period.

(See tables in the full report for more details)

7.5.1 Repeated dose toxicity: oral.002

UUID

IUC5-c2b1b0b7-0568-4483-b21c-54cfa1d1f5a7

Dossier UUID

0

Author

dra / National Institute of Health Sciences / Tokyo / Japan

Date

2017-02-15 15:35:18 JST

Remarks

Purpose flag

key study

Study result type

experimental result

Reliability

1 (reliable without restriction)

Rationale for reliability incl. deficiencies

GLP guideline study