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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 from supporting substance (structural analogue or surrogate)
Adequacy of study:
weight of evidence
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: see 'Remark'
Remarks:
Guideline study with acceptable restrictions (Lack of data on test substance. Not all required organs were weighed and examined during necropsy (only liver, kidneys, adrenals, brain and testes/ovaries) and histopathology (only liver, kidneys, adrenals, heart, spleen, lung, testes/ovaries and gross lesions))

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
1995
Report Date:
1995

Materials and methods

Test guideline
Qualifier:
equivalent or similar to
Guideline:
OECD Guideline 407 (Repeated Dose 28-Day Oral Toxicity in Rodents)
Deviations:
yes
Remarks:
(not all required organs were examined during necropsy and histopathology, positive control was included)
GLP compliance:
yes

Test material

Reference
Name:
Unnamed
Type:
Constituent
Details on test material:
- Name of test material (as cited in study report): only trade name given
- Physical state: pale yellow liquid
- Analytical purity: no data
- Storage condition of test material: room temperature

Test animals

Species:
rat
Strain:
other: Crl:CD BR
Sex:
male/female
Details on test animals and environmental conditions:
TEST ANIMALS
- Source: Charles River Laboratories, Stone Ridge, NY, USA
- Age at study initiation: approximately 7 weeks
- Weight at study initiation: 216.6 - 251.2 g (males); 161.9 - 187.8 g (females)
- Assigned to test groups randomly: yes, by a computer-generated body weight sorting program
- Housing: the animals were housed individually in suspended stainless steel and wire mesh cages with absorbent paper below the cages.
- Diet: certified Rodent Diet # 5002 (pellets) (PMI Feeds Inc.), ad libitum
- Water: tap water, ad libitum
- Acclimation period: 13 d

ENVIRONMENTAL CONDITIONS
- Temperature (°C): 20 - 24
- Humidity (%): 40 - 70
- Photoperiod (hrs dark / hrs light): 12/12

IN-LIFE DATES:
From: 28 Sep 1994
To: 27 Oct 1994

Administration / exposure

Route of administration:
oral: gavage
Vehicle:
other: polyethylene glycol (PEG 400)
Details on oral exposure:
PREPARATION OF DOSING SOLUTIONS: The test substance was diluted in the vehicle to a concentration of 2% (w/v).

VEHICLE
- Justification for use and choice of vehicle (if other than water): the test substance was soluble in PEG 400 at the concentrations required for this study.
- Concentration in vehicle: 2% (w/v)
- Amount of vehicle (if gavage): 5 mL/kg bw
Analytical verification of doses or concentrations:
yes
Details on analytical verification of doses or concentrations:
The stability, uniformity and concentration of the test substance and the positive control substance in their vehicles were analysed. The analysis for the stability and uniformity were initiated prior to or concomitant with the initiation of dosing. Concentration analysis were performed for the mixtures of weeks 1 and 4.
A solution of 2% (w/v) test substance in PEG 400 was stable for at least 8 d at room temperature. The relative standard deviation of a solution of 2% of the test substance in PEG 400 was 0.732. The analysis of the concentration indicated that all solutions were within 9% of the nominal concentrations for weeks 1 and 4.
Duration of treatment / exposure:
28 d
Frequency of treatment:
once daily, 7 d/week
Doses / concentrations
Remarks:
Doses / Concentrations:
100, 500 and 1000 mg/kg bw/d
Basis:
actual ingested
No. of animals per sex per dose:
5
Control animals:
yes, concurrent vehicle
Positive control:
acrylamide

Examinations

Observations and examinations performed and frequency:
CAGE SIDE OBSERVATIONS: Yes
- Time schedule: twice daily monday through friday, once daily on weekends and holidays

DETAILED CLINICAL OBSERVATIONS: Yes
- Time schedule: daily

BODY WEIGHT: Yes
- Time schedule for examinations: on the day of initiation of dosing (Day 0), on Days 7, 14, 21, 27 and on the day of sacrifice (Day 28)

FOOD CONSUMPTION AND COMPOUND INTAKE:
- Food consumption for each animal determined and mean daily diet consumption calculated as g food/kg body weight/day: Yes
- Time schedule: weekly

HAEMATOLOGY: Yes
- Time schedule for collection of blood: Day 28
- Anaesthetic used for blood collection: es, methoxyflurane
- Animals fasted: Yes
- How many animals: all surviving animals
- Parameters observed: hematocrit, hemoglobin, erythrocyte count, leukocyte count (total and differential), platelet count, reticulocyte count, mean corpuscular volume, mean corpuscular hemoglobin and mean corpuscular hemoglobin concentration; to estimate the clotting potential prothrombin time and thromboplastin time were observed

CLINICAL CHEMISTRY: Yes
- Time schedule for collection of blood: Day 28
- Animals fasted: Yes
- How many animals: all surviving animals
- Parameters observed: albumin, urea nitrogen, calcium, creatinine, electrolytes (Na+, CI-, K+), glucose, phosphorus, gamma glutamyl transpeptidase, serum alanine aminotransferase, serum aspartate aminotransferase, serum alkaline phosphatase, total protein, total bilirubin, cholesterol and triglycerides

NEUROBEHAVIOURAL EXAMINATION: Yes
- Time schedule for examinations: prior to initiation of dosing, on Day 8 and on the last day of dosing (both at least 1 h after dosing)
- Dose groups that were examined: all surviving animals
Sacrifice and pathology:
GROSS PATHOLOGY: Yes, including organ weights of liver, kidneys, adrenals, brain and testes/ovaries
HISTOPATHOLOGY: Yes, histopathological examination of liver, kidneys, adrenals, spleen, heart, lungs, testes/ovaries and gross lesions from the animals of the vehicle and positive control groups and the high dose group; histopathological examination of liver, kidneys, lungs and gross lesions from the animals of the low and mid dose groups.
Statistics:
The statistical evaluation of equality of means was done by an appropriate one way analysis of variance (ANOVA) and a test for ordered response in the dose groups. To determine if the dose groups have equal variance, Bartlett's Test was performed. If the variances were equal, the testing was done using parametric methods, otherwise nonparametric techniques were used.
For the parametric procedures, a standard one way ANOVA using the F distribution to assess significance was used. If significant differences among the means were indicated, Dunnett's Test was used to determine which treatment groups differed significantly from control. In addition to the ANOVA, a standard regression analysis for linear response in the dose groups was performed. The regression also tested for linear lack of fit in the model.
For the nonparametric procedures the test of equality of means was performed using the Kruskal-Wallis Test. If significant differences among the means were indicated, Dunn's Summed Rank Test was used to determine which treatment groups differed significantly from the control. In addition to the Kruskal-Wallis Test, Jonckheere's Test for monotonic trend in the dose response was performed.
Bartlett's Test for equal variance was conducted at the 1% level of significance. All other tests were conducted at the 5% and 1% level of significance.

Results and discussion

Results of examinations

Clinical signs:
effects observed, treatment-related
Description (incidence and severity):
but no treatment-related effects
Mortality:
mortality observed, treatment-related
Description (incidence):
but no treatment-related effects
Body weight and weight changes:
no effects observed
Food consumption and compound intake (if feeding study):
no effects observed
Food efficiency:
not examined
Water consumption and compound intake (if drinking water study):
not examined
Ophthalmological findings:
not examined
Haematological findings:
effects observed, treatment-related
Description (incidence and severity):
but no dose-response pattern
Clinical biochemistry findings:
effects observed, treatment-related
Description (incidence and severity):
but no dose-response pattern
Urinalysis findings:
not examined
Behaviour (functional findings):
effects observed, treatment-related
Description (incidence and severity):
but no dose-response pattern
Organ weight findings including organ / body weight ratios:
effects observed, treatment-related
Description (incidence and severity):
but no dose-response pattern
Gross pathological findings:
effects observed, treatment-related
Description (incidence and severity):
but no treatment-related effects
Histopathological findings: non-neoplastic:
effects observed, treatment-related
Description (incidence and severity):
but no treatment-related effects
Histopathological findings: neoplastic:
not examined
Details on results:
CLINICAL SIGNS AND MORTALITY
One male animal of the 500 mg/kg bw group died after the first application due to a gavage error. This animal was replaced on Day 1 with another animal, that received one less dose than the other animals. All animals survived the study period to the scheduled termination.
No clinical signs occurred that were judged to be related to the treatment with the test substance. In one or more groups including the controls, there were single or very low incidences of scabs (1/5 males in the control and in the mid dose group), sores (1/5 males in the control and in the mid dose group), dental abnormalities (1/5 males in the mid and high dose group), red material penis (1/5 males in the mid dose group), dry rales (1/5 females in the low and high dose group) and alopecia (1/5 males in the control group) observed. Soft stool was observed in 1/5 males and 2/5 females of the control group, 3/5 females of the low dose group, 3/5 males and 1/5 females of the mid dose group and 4/5 females of the high dose group.

BODY WEIGHT AND WEIGHT GAIN
No effects on the body weight were observed after treatment of the animals with the test substance.

FOOD CONSUMPTION AND COMPOUND INTAKE
No effects on the food consumption of the test substance treated animals were observed.

HAEMATOLOGY
There were no significant differences in the hematology parameters between the negative control and the animals received the test substance. The hemoglobin of the females of the low dose group was slightly decreased compared to the negative control. This effect was not considered to be clinically significant due to the absence of similar findings in other red blood cell parameters and a dose-response pattern.

CLINICAL CHEMISTRY
There were no significant differences in the clinical chemistry parameters between test substance treated and negative control animals which were judged to be test substance related. In male animals, statistically significant decreases in mean calcium, total protein and albumin in the mid dose group and an increase in alanine aminotransferase in the low dose group were observed. These effects were not considered to be clinically significant due to the absence of a clear dose-response pattern.

NEUROBEHAVIOUR
The neurobehavioural observations made on Day 8 and Day 27 were unremarkable for the animals treated with the test substance.
On Day 8, the following anomalities in neurobehaviour were observed: increased respiration in 1/5 males at 100 mg/kg bw/d and 1/5 females at 500 mg/kg bw/d, decreased toe pinch response in 1/5 females at 100 mg/kg bw/d and 2/5 males at 1000 mg/kg bw/d, increased toe pinch response in 1/5 females of the negative control and abnormal air righting in 1/5 males at 1000 mg/kg bw/d.
On Day 27, there was an increased incidence of decreased arousal in 3/5 males and 4/5 females of the negative control group, 5/5 males and 3/5 females at 100 mg/kg bw/d, 2/5 males and 1/5 females at 500 mg/kg bw/d and 4/5 males and 1/5 females at 1000 mg/kg bw/d. Irregular breathing was observed in 4/5 males and 2/5 females of the negative control group, 3/5 males and 1/5 females at 100 mg/kg bw/d, 2/5 males and 1/5 females at 500 mg/kg bw/d and 1/5 males and 1/5 females at 1000 mg/kg bw/d. Additionally, there occurred increased muscle tone in one male of the negative control group, slightly impaired gait in 1/5 males of the negative control group, decreased startle response in 1/5 males of the negative control group, increased arousal in 1/5 males at 1000 mg/kg bw/d and decreased toe pinch response in 1/5 males of the negative control group and 1/5 females at 1000 mg/kg bw/d.
Due to the absence of a dose-response pattern, these effects were judged to be incidental and not related to treatment.

ORGAN WEIGHTS
There were no significant differences in mean absolute organ weight between the test substance treated and negative control animals. In the mid dose group, there was a statistically significant increase in the mean relative testes weight. Due to the absence of a dose-response pattern, this effect was judged to be incidental.

GROSS PATHOLOGY
The necropsy revealed no treatment-related findings. Single incidences of dilated renal pelvis (1/5 males at 100 mg/kg bw/d), scabs (1/5 males at 500 mg/kg bw/d), thickened/roughened stomach (1/5 females at 500 mg/kg bw/d) and distended uterus (1/5 females at 500 mg/kg bw/d) were observed. These findings were considered to be incidental and not treatment-related.

HISTOPATHOLOGY: NON-NEOPLASTIC
No treatment-related histopathologic changes were observed in any of the organs or tissues examined. The most common spontaneously occurring incidental findings were focal mononuclear or mixed inflammatory cell infiltrations in the liver (5/5 males and 5/5 females of the negative control, 5/5 males and 1/5 females at 100 mg/kg bw/d, 3/5 males and 5/5 females at 500 mg/kg bw/d, 2/5 males and 4/5 females at 1000 mg/kg bw/d) and the heart (2/5 males and 0/5 females of the negative control and 2/5 males and 0/5 females at 1000 mg/kg bw/d). Furthermore, focal tubular degeneration in the kidneys of male rats of all groups (4/5 of the negative control, 5/5 at 100 mg/kg bw/d, 2/5 at 500 mg/kg bw/d, 4/5 males at 1000 mg/kg bw/d) was observed. This effect was not observed in any dose group in the kidneys of the female rats.
The changes observed were considered to have been spontaneous in origin and were typical of incidental findings commonly encountered in laboratory rats of this age and strain. Because these changes occurred at similar incidence and intensity among all groups, they were not considered to be related to treatment.

Effect levels

Dose descriptor:
NOAEL
Effect level:
>= 1 000 mg/kg bw/day (actual dose received)
Based on:
test mat.
Sex:
male/female
Basis for effect level:
other: NOAEL corresponds to the highest dose tested

Target system / organ toxicity

Critical effects observed:
not specified

Applicant's summary and conclusion