2,3,5-trimethylhydroquinone

Repeated dose toxicity: oral

Administrative data

Endpoint:

short-term repeated dose toxicity: oral

Type of information:

experimental study

Adequacy of study:

key study

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: GLP guideline study.

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

1996

Report date:

1996

Materials and methods

Test guideline

Qualifier:

according to guideline

Guideline:

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

GLP compliance:

yes

Limit test:

no

Test material

Test material information

Constituent 1

Reference substance name:

2,3,5-trimethylhydroquinone

EC Number:

211-838-3

EC Name:

2,3,5-trimethylhydroquinone

Cas Number:

700-13-0

Molecular formula:

C9H12O2

IUPAC Name:

2,3,5-trimethylbenzene-1,4-diol

Details on test material:

- Name of test material (as cited in study report): Trimethylhydroquinone
- Physical state: yellow powder
- Analytical purity: 99 .8%
- Purity test date: Nov 09, 1994
- Lot/batch No.: 4361662
- Stability under test conditions:
purity and chemical identification of the test material was determined prior to the start of the study and at the end of the study.
- Storage condition of test material:
room temperature (19/08/93 to 14/09/93)
afterwards: room temperature in the dark, over
silica gel, under nitrogen gas

Test animals

Species:

rat

Strain:

Sprague-Dawley

Sex:

male/female

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Source: Charles River (U .K .) Limited, Manston, Kent
- Age at study initiation:
- Weight at study initiation: 131-165g (males), 124-158g (females)
- Fasting period before study:
- Housing: groups of five by sex in polypropylene gridfloor cages suspended over trays lined with absorbent paper
- Diet: pelleted diet (Rat andMouse SQC Expanded Diet No . 1, Special Diets Services Limited, Witham, Essex, U .K .) ad libitum
- Water: ad libitum
- Acclimation period: 7d


ENVIRONMENTAL CONDITIONS
- Temperature (°C): 20-22
- Humidity (%): 44-61
- Air changes (per hr): minimum of 15
- Photoperiod (hrs dark / hrs light): 12/12


IN-LIFE DATES: From: Oct 6, 1993 To: Nov 3, 1993

Administration / exposure

Route of administration:

oral: gavage

Vehicle:

arachis oil

Details on oral exposure:

VEHICLE
- Concentration in vehicle: 0, 22.5; 62.5; 200 mg/ml
- Amount of vehicle (if gavage): 2 ml/kg

Analytical verification of doses or concentrations:

yes

Duration of treatment / exposure:

28 days

Frequency of treatment:

daily

Doses / concentrations

Remarks:

Doses / Concentrations:
45, 125, 400 mg/kg bw/d
Basis:
actual ingested

No. of animals per sex per dose:

5

Control animals:

yes, concurrent vehicle

Details on study design:

Post-exposure period: none

Examinations

Observations and examinations performed and frequency:

DETAILED CLINICAL OBSERVATIONS: Yes
- Time schedule:
All animals were examined for overt signs of toxicity, ill-health or
behavioural change immediately before dosing and one and five hours
after dosing during the working week . Animals were observed immediately
before dosing and one hour after dosing at weekends .


BODY WEIGHT: Yes
- Time schedule for examinations:
Individual bodyweights were recorded on Day 0 (the day before the
start of treatment) and on Days 7, 14, 21 and 28 . Bodyweights were
also recorded at terminal kill .

FOOD CONSUMPTION:
Food consumption was recorded for each cage group at weekly intervals
throughout the study .

FOOD EFFICIENCY:
- Body weight gain in kg/food consumption in kg per unit time X 100 calculated as time-weighted averages from the consumption and body weight gain data: No


OPHTHALMOSCOPIC EXAMINATION: Yes / No / No data
- Time schedule for examinations:
- Dose groups that were examined:


HAEMATOLOGY: Yes
- Time schedule for collection of blood: day 28
- Anaesthetic used for blood collection: Yes (identity) / No / No data
- Animals fasted: No
- How many animals: all surviving animals
- Parameters:
Haematocrit, Haemoglobin, Erythrocyte count, Total leucocyte count, Differential leucocyte count
Anisocytosis, Polychromatic erythrocyte count, Micronucleated erythrocyte count, Platelet count , mean corpuscular haemoglobin, mean corpuscular volume, mean corpuscular haemoglobin concentration, clotting time


CLINICAL CHEMISTRY: Yes
- Time schedule for collection of blood: day 28
- Animals fasted: No
- How many animals: all surviving animals
- Parameters:
Blood urea, Calcium, Total protein, Inorganic phosphorus, Albumin, Alkaline phosphatase, Albumin/globulin ratio, Alanine aminotransferase, Aspartate aminotransferase, Sodium Glucose, Potassium ,Total bilirubin,Chloride, Creatinine

URINALYSIS: Yes
- Time schedule for collection of urine: during week 4 (collection time 16h)
- Metabolism cages used for collection of urine: Yes
- Animals fasted: No
- Parameters :
Volume, Specific gravity, pH, Protein, Glucose, Ketones, Bilirubin, Urobilinogen, Reducing substances, Blood


NEUROBEHAVIOURAL EXAMINATION: No

Sacrifice and pathology:

GROSS PATHOLOGY: Yes
All animals were subjected to a full external and internal examination, and any macroscopic abnormalities were recorded .

ORGAN WEIGHTS:
Adrenals, Brain, Gonads, Heart, Kidneys,
Liver, Pituitary, Spleen, Uterus

HISTOPATHOLOGY: Yes
Adrenals, Jejunum, Sciatic nerve, Aorta (thoracic), Kidneys, Seminal vesicles,
Bone & Bone Marrow ((femur, sternum) , Liver, Skin (hind limb)
Lungs, Spleen, Lymph nodes (cervical and mesenteric), Spinal Cord (cervical), Brain, Muscle (skeletal), Stomach,
Caecum, Oesophagus, Testes,Colon, Ovaries, Thymus,
Duodenum, Pancreas, Thyroid/parathyroid, Eyes, Pituitary, Trachea,Gross lesions, Prostate, Urinary bladder,
Heart, Rectum, Uterus, Ileum, Salivary glands

Statistics:

Absolute and relative organ weights, haematological and blood chemical
data were analysed by one way analysis of variance incorporating
'F-max' test for homogeneity of variance . Data showing heterogeneous
variances were analysed using Kruskal Wallis non-parametric analysis of
variance and Mann Whitney U-Test .

Results and discussion

Results of examinations

Details on results:

CLINICAL SIGNS AND MORTALITY
400 mg/kg/day:
Several females dosed at 400 mg/kg/day showed clinically observable signs of toxicity during the first three days of treatment . One animal appeared pale towards the end of Day 1 whilst another was hunched and lethargic during Days 2 and 3 . These two animals quickly recovered and appeared normal in comparison with controls from Days 2 and 4 respectively . A further female from this dose group was pale and lethargic approximately one hour after dosing on Day 1 and showed respiratory abnormalities . This animal was found dead approximately ten minutes after the observations had been performed . There were no further deaths during the study . Animals of either sex dosed at 400 mg/kg/day also showed increased salivation immediately after dosing from Day 9 onwards .
125 or 45 mg/kg/day: no clinical signs of toxicity

BODY WEIGHT AND WEIGHT GAIN
Animals treated with the test material showed similar bodyweight gains to
controls over the treatment period .

FOOD CONSUMPTION
There was no adverse effect on food consumption during the study .

WATER CONSUMPTION
400 mg/kg/day; slightly greater water intake than controls during the study .
No appreciable differences in water intake were evident at the remaining
dose levels.

HAEMATOLOGY
400 mg/kg bw/d: Animals of either sex had a slightly lower haemoglobin
concentration, erythrocyte count, haematocrit and mean corpuscular
haemoglobin concentration than controls together with a slightly elevated
mean corpuscular volume . In addition, these animals showed a significantly
higher number of polychromatic erythrocytes than controls together with a
marginally higher incidence of micronucleated cells. Total leucocyte counts
were also slightly higher in males than in controls.
125 or 45 mg/kg/day: no treatment-related changes

CLINICAL CHEMISTRY
400 mg/kg/day: Animals of either sex dosed had a higher total plasma
protein concentration than controls . Female plasma albumin concentration
was also raised at this dose level whilst male albumin/globulin ratio was
reduced.
125 or 45 mg/kg/day: no treatment-related changes

URINALYSIS
no treatment-related changes

ORGAN WEIGHTS
400 mg/kg/day : Males showed a statistically significant increase in
spleen weight (absolute and relative) and females showed increased relative spleen weights.
Animals of either sex showed a statistically
significant increase in relative liver weight c whilst
an increase in absolute liver weight was confined to females.
125 mg/kg/day : males showed increased relative spleen weights.
No other test substance related changes were observed.

GROSS PATHOLOGY
No toxicologically significant macroscopic abnormalities

HISTOPATHOLOGY
400 mg/kg/day:
spleen: increased severities of extramedullary haemopoiesis, characterised as essentially erythropoiesis ,
and haemosiderin pigment deposition were observed in relation to treatment ,
for rats of either sex. No treatment-related microscopic changes were identified in the sections of bone marrow examined
and an increased severity of haemosiderin pigment deposition was not evident in either the liver or the kidneys at this dose level .

45, 125 mg/kg/day:
Increased severity of splenic extramedullary haemopoiesis in male rats.

No morphological abnormalities were detected for female rats dosed at 125 or
45 mg/kg/day.

Effect levels

1

Dose descriptor:

NOAEL

Effect level:

125 mg/kg bw/day (nominal)

Sex:

male/female

2

Dose descriptor:

LOAEL

Effect level:

400 mg/kg bw/day (nominal)

Sex:

male/female

Target system / organ toxicity

Critical effects observed:

not specified