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Toxicological information

Repeated dose toxicity: oral

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Administrative data

Endpoint:
short-term repeated dose toxicity: oral
Type of information:
migrated information: read-across based on grouping of substances (category approach)
Adequacy of study:
weight of evidence
Study period:
Nov - Dec 1992
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: see 'Remark'
Remarks:
GLP - Guideline study. According to the ECHA guidance document "Practical guide 6: How to report read-across and categories (March 2010)", the reliability was changed from RL1 to RL2 to reflect the fact that this study was conducted on a read-across substance.

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
1993
Report Date:
1993

Materials and methods

Test guideline
Qualifier:
equivalent or similar to
Guideline:
OECD Guideline 407 (Repeated Dose 28-Day Oral Toxicity in Rodents)
Deviations:
no
GLP compliance:
yes
Limit test:
no

Test material

Reference
Name:
Unnamed
Type:
Constituent

Test animals

Species:
rat
Strain:
other: Alpk:APfSD
Sex:
male/female
Details on test animals and environmental conditions:
TEST ANIMALS
- Source: Zeneca Pharmaceuticals, Alderly Park, Macclesfield, Cheshire, UK
- Age at study initiation: 28 d
- Weight at study initiation: 148.45 g (males); 122.6 g (females)
- Housing: sexes separately, five per cage, cages had measurements of 26.5 x 50.0 x 20.0 cm and were constructed of stainless steel mesh with one solid side.
- Diet: CT1 diet; Special Diets Services Limited, Witham, Essex, UK
- Water: tap water, ad libitum
- Acclimation period: approx. 1 week

ENVIRONMENTAL CONDITIONS
- Temperature (°C): 19-23
- Humidity (%): 45-65 (71 at one occasion)
- Air changes (per hr): 25-30
- Photoperiod (hrs dark / hrs light): 12 / 12

IN-LIFE DATES: From: November 1992 To: December 1992

Administration / exposure

Route of administration:
oral: feed
Vehicle:
other: in diet
Details on oral exposure:
PREPARATION OF DOSING SOLUTIONS: All diet preparations were based on CT1 diet (Special Diets Services Limited, Witham, Essex, UK). They were prepared by grinding the appropriate amount of test substance with 1 kg of milled CT1 diet. This premix was then added to 14 kg of diet and mixed thoroughly with a Pharma Blender Model PMA 100S (T K Filder).

DIET PREPARATION
- Rate of preparation of diet (frequency): 15 kg batches
- Mixing appropriate amounts with (Type of food): CT1 diet (Special Diets Services Limited, Witham, Essex, UK)
- Storage temperature of food: - 20°C, stored at room temperature for usage up to 14 days
Analytical verification of doses or concentrations:
yes
Details on analytical verification of doses or concentrations:
Chemical stability was determined for diet preparations over a period of 5 weeks following storage at room temperatureT or at -20°C.
Samples were extracted by chemical shaking with ethyl acetate. The supernatant was diluted with ethyl acetate to give solutions containing appropriate concentrations of the test substance. Extracts were analysed by gas chromatography using flame ionisation detection. The extract concentration was calculated by reference to data from a standard containing a known concentration.
Duration of treatment / exposure:
daily
Frequency of treatment:
28 d
Doses / concentrationsopen allclose all
Remarks:
Doses / Concentrations:
1000 ppm, 5000 ppm, 12500 ppm
Basis:
nominal in diet
Remarks:
Doses / Concentrations:
112, 562, 1450 mg/kg bw/d
Basis:
other: actual ingested for males
Remarks:
Doses / Concentrations:
119, 586, 1613 mg/kg bw/d
Basis:
other: actual ingested for females
No. of animals per sex per dose:
5
Control animals:
yes
Details on study design:
- Dose selection rationale: Based on results of preliminary feeding studies

Examinations

Observations and examinations performed and frequency:
CAGE SIDE OBSERVATIONS: Yes
- Time schedule: Daily
- Cage side observations checked: changes in clinical condition and behaviour and significant changes were recorded.

DETAILED CLINICAL OBSERVATIONS: Yes
- Time schedule: on Days 8, 15, 22, 29
- observations included, but were not limited to the assessment of autonomic function (e.g. lacrimation, salivation, piloerection, exophthalmus, urination, defecation, pupillary function, ptosis); description, incidence and severity of any convulsions, tremors, abnormal motor function, alteration in respiration, reactivity to stimuli, changes in the level of arousal, sensorimotor responses

BODY WEIGHT: Yes, measurement in replicate order immediately before feeding and at the same day once a week until termination.

FOOD CONSUMPTION AND COMPOUND INTAKE:
- Food consumption for each animal determined and mean daily diet consumption calculated as mg food/kg body weight: Yes, on a weekly basis
- Compound intake calculated as time-weighted averages from the consumption and body weight gain data: Yes

HAEMATOLOGY: Yes
At termination, all rats were bled by cardiac puncture and samples were collected. Parameters determined: Hemoglobin, red cell count, haematocrit, mean cell volume, mean cell haemoglobin, mean cell haemoglobin concentration, platelet count, white blood cell count, neutrophil count, lymphocyte count, monocyte count, eosinophil count, prothrombin time and kaolin-cephalin time

CLINICAL CHEMISTRY: Yes
At termination, all rats were bled by cardiac puncture and samples were collected. Parameters determined: Albumin, total protein, cholesterol, triglycerides, urea, creatinine, glucose, total bilirubin and alkaline phosphatase, plasma gamma-glutamyl transferase, plasma alanine aminotransferase, plasma aspartate aminotransferase, plasma creatine kinase, plasma sodium, plasma potassium, plasma chloride, plasma calcium and plasma phosphorus

NEUROBEHAVIOURAL EXAMINATION: Yes
- Time schedule for examinations: on Days 8, 15, 22, 29
- Dose groups that were examined: All
- Battery of functions tested: sensory activity / grip strength
Sacrifice and pathology:
GROSS PATHOLOGY: Yes

HISTOPATHOLOGY: Yes (adrenals, aorta, bladder, bone and bone marrow (femur), brain, caecum, colon, cervical lymph node, cervix, colon, duodenum, epididymis, eye and harderian gland, heart, ileum, jejunum, kidney, liver, lungs, mammary gland, mesenteric lymph node, nasal passages, oesophagus, oral cavity, ovaries, pancreas, parathyroid glad, pituary gland, prostate gland, rectum, salivary glands, sciatic nerve, seminal vesicles, skin, spinal chord, spleen, sternum, stomach, testes, thymus, thyroid gland, trachea, uterus, voluntary muscle)
Statistics:
Bodyweights were considered by analysis of covariance on initial body weight, separately for males and females.
Time to tail flick and fore and hindlimb grip strength at weeks 2, 3, 4 and 5 were considered by analysis of variance, separately for both sexes.
Haematological and clinical blood parameters were considered by analysis of variance.
Organ weights were considered by analysis of variance and covariance on final body weight separately for both sexes.

Results and discussion

Results of examinations

Clinical signs:
no effects observed
Mortality:
no mortality observed
Body weight and weight changes:
no effects observed
Food consumption and compound intake (if feeding study):
no effects observed
Haematological findings:
effects observed, treatment-related
Description (incidence and severity):
reduction in haemoglobin and haematocrit (males), reductions in haemoglobin, haematocrit and in white blood cell count (females).
Clinical biochemistry findings:
effects observed, treatment-related
Description (incidence and severity):
minor reductions in plasma cholesterol, triglyceride, total protein levels and plasma alanine transferase activities in males
Behaviour (functional findings):
no effects observed
Organ weight findings including organ / body weight ratios:
effects observed, treatment-related
Description (incidence and severity):
increased kidney weights (males), slightly increased kidney weights (females), increased liver weights (males/females) in 5000 and 12500 ppm groups
Gross pathological findings:
no effects observed
Histopathological findings: non-neoplastic:
effects observed, treatment-related
Description (incidence and severity):
kidney: increased tubular hyaline droplet formation, tubular basophilia, granular cast formation (males). liver: minimal hepatocyte hypertrophy in 4/5 male rats
Histopathological findings: neoplastic:
no effects observed
Details on results:
DIET ANALYSIS:
All diets prepared were found to be within 4% of the target concentration. The homogeneity of the test material in the diet, determined at 1000 and 12500 ppm inclusion levels was within 2 % of the overall mean concentration for both levels. Chemical stability of the test material, assessed at the 1000 and 12500 ppm inclusion levels stored at room temperature or at -20 °C was satisfactory over the period of use.
Dose rates (based on nominal dietary levels) were highest at the start of the study and declined rapidly during the period of rapid growth to week 4.

MORTALITY
There were no mortalities.

FUNCTIONAL OBSERVATION BATTERY
A slightly reduced splay reflex was observed in one female of the 1000 ppm group (on days 29 and 30), in one male of the 5000 ppm group (on day 29) and in one male of the 12.500 ppm group (on day 29). As isolated observations, these were considered to be incidental.
There were no differences in time to tail flick in either sex which could be attributed to treatment. The statistically significant increase in time to response observed on day 22 for males (5000 ppm) and day 8 for females (1000 ppm) were considered to be incidental to treatment in the absence of similar changes at higher dose levels.
There was no evidence of any treatment related effects on forelimb or hindlimb grip strength.
Any other statistically significant changes were considered spurious and unrelated to treatment with the test material.

BODY WEIGHT AND WEIGHT GAIN
There were no statistically significant effects on body weight and all final bodyweights were within 3% of the respective controls, after adjusting for initial weight differences.

FOOD CONSUMPTION
Food consumption in all treated groups remained similar to, or exceeded that, of the respective control group throughout the study.

HAEMATOLOGY
There were statistically significant reductions in haemoglobin and haematocrit at 12.500 ppm in male rats. Statistically significant reductions in haemoglobin and haematocrit were seen in females at 1000 and 5000 ppm and in white blood cell count at 1000 ppm. In the absence of a coherent dose-response relationship, these differences were considered incidental to treatment.
Any other statistically significant changes were considered spurious and unrelated to treatment with the test material.

CLINICAL CHEMISTRY
There were minor reductions in plasma cholesterol, triglyceride and total protein levels and plasma alanine transferase activities in males at 12500 ppm compared to controls. Any other statistically significant changes were considered spurious and unrelated to treatment with the test material.
ORGAN WEIGHTS
Kidney weights adjusted for body weight were statistically significant increased in males at 5000 and 12500 ppm. All the females in the treatment groups had slightly raised kidney weights compared to control, but none achieved statistical significance, and there was no evidence of a coherent dose response relationship.
Liver weights adjusted for body weight were statistically significant increased in both sexes at 12500 ppm and in males at 5000 ppm.
Any other statistically significant changes were considered spurious and unrelated to treatment with the test material.

PATHOLOGY:
Macroscopic findings:
No treatment-related macroscopic findings were apparent at the end of the study.
HISTOPATHOLOGY:
Microscopic findings:
Treatment related findings were present in the kidney of male rats from all dose groups. In the 5000 and 12500 ppm dose group these comprised increased tubular hyaline droplet formation and tubular basophilia in all animals, and granular cast formation in four of the 5000 ppm animals and all of the 12500 ppm animals; the latter occurring at the cortico-medullary injection. In the 1000 ppm group, increased renal hyaline droplet formation and/or tubular basophilia were seen, but not granular cast formation.
In the liver, there was minimal hepatocyte hypertrophy in 4/5 male rats in the 12500 ppm group.

The increased kidney weights and microscopic findings of renal tubular basophilia, granular cast formation and increased hyaline droplet formation present in male rats at 5000 and 12.500 ppm are clearly treatment related. These findings are consistent with the well characterized light hydrocarbon nephropathy described for male rats, following to a variety of chemicals including light hydrocarbons such as unleaded gasoline and trimethyl pentane. The characteristics include an increased accumulation of hyaline droplets in male rat kidneys, the main constituent of which is alpha 2µ-globulin (Alden et al. Adv. Modern Environ Toxicol 7: 107-120 (1984); Stonard et al. Renal Heterogeneity and Target Cell Toxicity. Bach PH and Lock EA Eds, John Wiley and Sons (1985)). It is widely accepted that this phenomenon is specific to male rat and as such appears to have no relevance for man (Swenberg et al. Toxicol and App. Pharmacol. 97: 35-46 (1989)).

Effect levels

open allclose all
Dose descriptor:
NOAEL
Effect level:
1 613 mg/kg bw/day (actual dose received)
Based on:
test mat.
Sex:
female
Basis for effect level:
other: No effects observed in female rats
Dose descriptor:
NOAEL
Effect level:
1 450 mg/kg bw/day (actual dose received)
Based on:
test mat.
Sex:
male
Basis for effect level:
other: corresponding to 12500 ppm

Target system / organ toxicity

Critical effects observed:
not specified

Applicant's summary and conclusion