diethyl 1-(2,4-dichlorophenyl)-5-methyl-4,5-dihydro-1H-pyrazole-3,5-dicarboxylate

Repeated dose toxicity: oral

Administrative data

Endpoint:

chronic toxicity: oral

Remarks:

combined repeated dose and carcinogenicity

Type of information:

experimental study

Adequacy of study:

key study

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

1994

Report date:

1994

Materials and methods

Test guideline

Test guideline 1

Qualifier:

according to guideline

Guideline:

OECD Guideline 453 (Combined Chronic Toxicity / Carcinogenicity Studies)

Deviations:

no

Test guideline 2

Qualifier:

according to guideline

Guideline:

other: EPA OPP 83-5

Deviations:

no

GLP compliance:

yes

Limit test:

no

Test material

Test material information

Constituent 1

Reference substance name:

diethyl 1-(2,4-dichlorophenyl)-5-methyl-4,5-dihydro-1H-pyrazole-3,5-dicarboxylate

EC Number:

603-923-2

Cas Number:

135590-91-9

Molecular formula:

C16H18Cl2N2O4

IUPAC Name:

diethyl 1-(2,4-dichlorophenyl)-5-methyl-4,5-dihydro-1H-pyrazole-3,5-dicarboxylate

Test animals

Species:

rat

Strain:

Wistar

Sex:

male/female

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Source: BRL, Biological Research Laboratories Ltd., CH-4414 Fuellinsdorf/Switzerland
- Age at study initiation: 4 weeks
- Weight at study initiation: males: 63-96 g (mean: 79 g) females: 42-74 g (mean: 58 g)
- Housing: groups of five in Makrolon type-4 cages with wire mesh tops and granulated softwood bedding (Lignocel, Schill AG, Muttenz/ Switzerland)
- Diet (e.g. ad libitum): pelleted standard Kliba 343 rat/mouse maintenance diet ("Kliba", Klingentalmuehle AG, 4303 Kaiseraugst/Switzerland), and was available ad libitum.
- Water (e.g. ad libitum): tap water ad libitum via water bottles
- Acclimation period: 7 days under test conditions, after veterinary examination.


ENVIRONMENTAL CONDITIONS
- Temperature (°C): 22 ± 3
- Humidity (%): 40 - 70 %
- Air changes (per hr): 10-15
- Photoperiod (hrs dark / hrs light): 12/12

Administration / exposure

Route of administration:

oral: feed

Vehicle:

acetone

Details on oral exposure:

DIET PREPARATION
Dissolved in acetone and mixed to microgranulated food, pelleted in a Buehler pelleting machine. Water was added to each feed preparation at an approximate 1:10 volume/weight ratio to ensure pelleting, after which the pellets were dried with warm air for approximately 48 hours before storage.
- Rate of preparation of diet (frequency): monthly up to treatment week 8, and every two weeks thereafter
- Mixing appropriate amounts with (Type of food): microgranulated feed
- Storage temperature of food: room temperature


VEHICLE
- Justification for use and choice of vehicle (if other than water): admixed to the diet, which is recognized as an efficacious method of absorption.

Analytical verification of doses or concentrations:

yes

Details on analytical verification of doses or concentrations:

Stability, homogeneity and content of the test article in feed was determined prior to study initiation with RCC Project 285028 and was repeated with the first diet batches prepared for the study. Intercurrent sampling for analyses (homogeneity and content) was performed every two months. Analyses were performed in the Analytical Chemistry Laboratory of RCC Umweltchemie AG according to a method supplied by the sponsor.

Duration of treatment / exposure:

124 weeks oncogenicity, 104 weeks chronic toxicity, 52 weeks interim sacrifice

Frequency of treatment:

continuously

Doses / concentrations

Doses / concentrations 1

Dose / conc.:

40 ppm

Remarks:

nominal in diet

Doses / concentrations 2

Dose / conc.:

200 ppm

Remarks:

nominal in diet

Doses / concentrations 3

Dose / conc.:

1 000 ppm

Remarks:

nominal in diet

Doses / concentrations 4

Dose / conc.:

5 000 ppm

Remarks:

nominal in diet

No. of animals per sex per dose:

80 (50 oncogenicity 124 weeks, 20 chronic toxicity 104 weeks, 10 interim sacrifice after 52 weeks)

Control animals:

yes, plain diet

Details on study design:

- Dose selection rationale: Based upon results of a subchronic toxicity study in the rat (RCC Project 285028), the top dose level (5000 ppm) was expected to cause a significant reduction in body weight gains, a slight anemia, urinary enzyme changes, and changes in liver function. The mid-high dose level (1000 ppm) was expected to cause minimal, if any, signs of toxicity. The lower dose levels (40 and 200 ppm) were expected to establish a "no observable effect level" (NOEL).

Examinations

Observations and examinations performed and frequency:

CAGE SIDE OBSERVATIONS: Yes
- Time schedule: mortality twice daily, clinical signs at least once daily
- Cage side observations included: mortality, clinical signs

DETAILED CLINICAL OBSERVATIONS: Yes
- Time schedule: weekly detailed clinical examination which included a palpation for tissue masses (except for acclimatization/pretest phase). A description of any lesion or mass observed at any examination was recorded and the subsequent progress monitored.

BODY WEIGHT: Yes
- Time schedule for examinations: weekly until week 13 and every two weeks thereafter using an on-line electronic recording system consisting of a
Mettler balance connected to the RCC computer system.

FOOD CONSUMPTION AND COMPOUND INTAKE (if feeding study):
The food consumption was recorded for a 7-day period. The data were recorded weekly until week 13 and every 2 weeks thereafter using an on-line electronic recording system consisting of a Mettler balance connected to the RCC computer system.
- Food consumption for each cage determined and average daily diet consumption calculated as g food/day: Yes
- Compound intake calculated as time-weighted averages from the consumption and body weight gain data: No, cage means were calculated as mg compound/kg bw/day.
- The relative food consumption (RFC) was calculated weekly as g food/kg bw/day.

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

WATER CONSUMPTION: Yes, mean water consumption values were calculated as g water /animal/day over the measurement intervals.
- Time schedule for examinations: once monthly in the first 3 months and every 3 months thereafter using an on-line electronic recording system, consisting of a Mettler balance connected to the RCC computer system, recorded over 24 hours.

OPHTHALMOSCOPIC EXAMINATION: Yes
- Time schedule for examinations: at pretest, 26, 51, 78 and 104 weeks
- Dose groups that were examined: all dose groups of the animals scheduled for assessment of chronic toxicity (20/sex/dose, actual number examined depending on survival). After the application of a mydriatic solution (Disperse AG, Winterthur, Switzerland) the cornea, lens, anterior chamber, vitreous body and ocular fundus of both eyes were examined using a Heine Miroflex 2 Ophthalmoscope (Eisenhut Vet AG, Allschwil/Switzerland).

HAEMATOLOGY: Yes
- Time schedule for collection of blood: Animals of the interim sacrifice group at 52 weeks, animals scheduled for assessment of chronic toxicity at 26, 52, 78 and 104 weeks. Blood samples were collected between 06.00 and 09.15 to reduce biological variation caused by circadian rhythms. Blood samples were drawn from the retro-orbital plexus using a micro-hematocrit glass capillary tube. Blood smears for differential blood counts were taken for all remaining animals scheduled for assessment of carcinogenicity at 123 weeks of treatment.
- Anaesthetic used for blood collection: Yes (light ether anaesthesia)
- Animals fasted: Yes, approximately 18 hours before blood sampling but allowed access to water ad libitum, animals of the carcinogenicity group were not fasted before blood sampling.
- How many animals: All animals (10/sex/dose) scheduled for interim sacrifice and half of the animals (10/sex/dose, with the lowest identification numbers) scheduled for assessment of chronic toxicity.
- Parameters examined: erythrocyte count, hemoglobin, hematocrit, mean corpuscular volume, mean corpuscular hemoglobin, mean corpuscular hemoglobin concentration, platelet count, reticulocyte count, nucelated erythrocytes (normoblasts), total leukocyte count, differential leukocyte count, red cell morphology, coagulation (thromboplastin time, activated partial thromboplastin time)

CLINICAL CHEMISTRY: Yes
- Time schedule for collection of blood: Animals of the interim sacrifice group at 52 weeks, animals scheduled for assessment of chronic toxicity at 26, 52, 78 and 104 weeks. Blood samples were collected between 06.00 and 09.15 to reduce biological variation caused by circadian rhythms. Blood samples were drawn from the retro-orbital plexus using a micro-hematocrit glass capillary tube.
- Animals fasted: Yes, approximately 18 hours before blood sampling but allowed access to water ad libitum.
- How many animals: All animals (10/sex/dose) scheduled for interim sacrifice and half of the animals (10/sex/dose, with the lowest identification numbers) scheduled for assessment of chronic toxicity.
- Parameters examined: glucose, urea, creatinine, bilirubin total, bilirubin direct, cholesterol total, triglycerides, aspartate aminotransferase, alanine aminotransferase, lactate dehydrogenase, alkaline phosphatase, gamma-glutamyltransferase, calcium, phosphorus, sodium, potassium, chloride, protein total, protein electrophoresis (albumin, alpha 1-globulin, alpha 2-globulin, sum of beta-globulins, gamma-globulin).

URINALYSIS: Yes
- Time schedule for collection of urine: Urine was collected from all animals of the interim sacrifice group at 52 weeks and from 10 animals/sex/dose (with the lowest identification numbers) scheduled for assessment of chronic toxicity at 26, 52, 78 and 104 weeks.
- Metabolism cages used for collection of urine: Yes, urine collected on ice during the 18-hours fasting period into a specimen vial.
- Animals fasted: Yes
- Parameters examined: volume, specific gravity, colour, appearance, pH, protein, glucose, ketone, bilirubin, blood, urobilinogen, urine sediment, gamma-glutamyltransferase, lactate dehydrogenase, alkaline phosphatase, leucine aminopeptidase, beta-N-Acetyl-D-glucosaminidase, sodium, phosphorus, potassium, protein total, creatinine, creatinine clearance, urea


NEUROBEHAVIOURAL EXAMINATION: No

Sacrifice and pathology:

GROSS PATHOLOGY:
Yes, all surviving animals and all animals which died spontaneously or were killed in extremis were necropsied and descriptions of all macroscopic abnormalities were recorded. All surviving animals were weighed prior to necropsy. Necropsies were performed by experienced prosectors supervised by a veterinary pathologist. All animals surviving to the end of the observation period and all moribund animals were anesthetized by intraperitoneal injection of sodium pentobarbital and killed by exsanguination. Samples of the following tissues and organs were collected from all animals at necropsy and fixed in neutral phosphate buffered 4 % formaldehyde solution (the tissues between brackets need to be examined only if indicated by signs of toxicity or target organ involvement): Adrenal glands, Aorta, Brain [including sections of medulla/pons, cerebral and cerebellar cortex], Cecum, Colon, Duodenum, Epididymides, Esophagus, Eyes - with optic nerve and Harderian gland, Femur [including joint], Heart, Ileum, Jejunum, Kidneys, (Larynx), Lacrimal gland [exorbital], Liver, Lungs [infused with formalin], Lymph nodes [mandibular, mesenteric], Mammary gland area, (Nasopharynx), Ovaries, Pancreas, Pituitary gland, Prostate gland, Rectum, Salivary gland [mandibular, sublingual], Sciatic nerve, Seminal vesicles, Skeletal muscle, Skin, Spinal cord [cervical, midthoracic, lumbar], Spleen, Sternum with bone marrow, Stomach, Testes, Thymus - if present, Thyroid gland/parathyroid, Tongue, Trachea, Urinary bladder [infused with formalin], Uterus, Vagina, All gross lesions and tumors

Samples of liver (approximately 2 grams) and kidneys (approximately 1 gram for males and approximately 0.7 gram for females), brain (1 gram), fatty
tissue (perirenal) and skeletal muscle for possible future tests were taken from interim sacrifice-animals at scheduled necropsy. The remainder of tissues was used for histopathological evaluations. The organ samples for biochemistry were placed on ice in labelled plastic bags, rinsed in ice-cold saline (0.9% NaCl solution), blotted dry and immediately frozen in liquid nitrogen, and stored at -80°C. Only organs without macroscopical abnormalities were used for these purposes.

HISTOPATHOLOGY: Yes
The tissues were embedded in paraffin. The sections were cut at an approximate thickness of 4 micrometers and stained with hematoxylin and eosin.
Sections of the following tissues from rats scheduled for interim sacrifice as well as from all animals that died or were killed in extremis were examined microscopically (number of sections per tissue):
Adrenal glands (2), aorta (1), bone [femur with stifle joint sternum] (2), bone marrow [sternum, femur] (2), brain (1), epididymides (2), esophagus (1), exorbital lacrymal glands (2), eyes with optic nerve (2), Harderian glands (2), heart (1), kidneys (2), large intestine [cecum, colon, rectum] (3), liver (2), lungs (2), lymph nodes [mandibular, mesenteric] (2), mammary gland area [female] (1), ovaries (2), pancreas (1), parathyroid glands (2), pituitary gland (1), prostate (1), salivary glands [sublingual, mandibular] (2), sciatic nerve (1), seminal vesicles (2), skeletal muscle (1), skin (1), small intestine [duodenum, jejunum, ileum] (3), spinal cord (3), spleen (1), stomach (1), testes (2), thymus (l), thyroid gland (2), tongue (1), trachea (1), urinary bladder (1), uterus (1), vagina (1) and all gross lesions.

Other examinations:

ORGAN WEIGHTS:
Brain, Adrenals, Kidneys, Heart, Liver, Pituitary, Lungs, Ovaries, Spleen, Thyroid, Testes

Statistics:

The following statistical methods were used to analyze the body weight, food consumption, water consumption, organ weights and clinical laboratory data :
Univariate one-way analysis of variance was used to assess the significance of intergroup differences. If the variables can be assumed to follow a normal distribution, the Dunnett test (many to one t-test) based on a pooled variance estimate was applied for the comparison between the treated groups and the control groups for each sex.
The Steel-test (many-one rank test) was applied when the data could not be assumed to follow a normal distribution.
The exact Fisher-test was applied to ophthalmoscopic examinations and overall spontaneous mortality data.
Statistical evaluation of neoplastic lesions was performed according to Peto et al., 1980, using the test for positive trend with respect to dose rates. Group means were calculated for continuous data and medians were calculated for discrete data (scores) in the summary tables.
Individual values, means, standard deviations and statistics were rounded-off before printing. For example, test statistics were calculated on the basis of exact values for means and pooled variances and then rounded-off to two decimal places. Therefore, two groups may display the same printed means for a given parameter, yet display different test statistics values.
The age-specific survival rate up to termination for each group and sex was calculated with Kaplan-Meier non-parametric estimates based on censored survival data, censorship being imposed on unnatural causes of death (death during blood sampling procedures, trauma, etc.).

Results and discussion

Results of examinations

Clinical signs:

no effects observed

Mortality:

no mortality observed

Body weight and weight changes:

effects observed, treatment-related

Food consumption and compound intake (if feeding study):

no effects observed

Food efficiency:

not examined

Water consumption and compound intake (if drinking water study):

no effects observed

Ophthalmological findings:

no effects observed

Haematological findings:

effects observed, treatment-related

Clinical biochemistry findings:

no effects observed

Urinalysis findings:

no effects observed

Behaviour (functional findings):

not examined

Organ weight findings including organ / body weight ratios:

no effects observed

Gross pathological findings:

no effects observed

Histopathological findings: non-neoplastic:

no effects observed

Histopathological findings: neoplastic:

no effects observed

Details on results:

CLINICAL SIGNS AND MORTALITY
Survival was not affected by the test article. For distribution of unscheduled deaths within the groups see table 1. Neither the type nor the incidences of the clinical signs (mainly alopecia) or of the nodules and masses noted indicated an effect of treatment with the test article.

BODY WEIGHT AND WEIGHT GAIN
Compared with the control group, group 5 (5000 ppm,) females had statistically significantly reduced mean body weights from start of treatment throughout the recording period. These constantly reduced values were considered to be a borderline effect of test article. At this dose level, no effects on the body weight of the male animals were evident. The difference between male and female animals was considered to be caused by the higher test article intake (ca. 26%) of the females in comparison with the respective males. In the dose groups 2 (40 ppm), 3 (200 ppm) and 4 (1000 ppm), the body weight development of the male and female animals was not considered to be affected by treatment with the test article.

In the group 4 (1000 ppm) males, body weight gain was increased in comparison with that of the control group. After reaching a peak of approximately 11% at 91 weeks the difference in body weight gain nearly disappeared until the end of study. In absence of any dose relationship this finding was considered to be incidental.

FOOD CONSUMPTION AND COMPOUND INTAKE (if feeding study)
Up to and including the highest dietary concentration of 5000 ppm, in both the male and female animals the differences in food consumption between the respective control group and the dose groups were not considered to be caused by treatment with the test article.
Generally, in both male and female animals of the dose groups relative food consumption compared favourably with that of the respective control animals. Although, in several cases differences from control values attained statistical significance, in particular for the group 5 (5000 ppm) animals, these findings were not considered to indicate test article related effects.

Test article intake was proportional to dietary concentrations and slightly higher in females than in males (see table 2).


WATER CONSUMPTION
In comparison with the control group, water consumption was increased in the males of group 5 (5000 ppm) during the first three recording periods (on days 17-18, 38-39 and 73-74 of treatment) and in the males of group 4 (1000 ppm) up to week 123 (last measurement). This finding was considered to be incidental and not test article related because no dose-relationship was evident between groups 4 (1000 ppm) and 5 (5000 ppm). Males of groups 1 (0 ppm), 2 (40 ppm) and 3 (200 ppm) and the female animals of all groups had similar water consumption.
As for absolute water consumption, relative water consumption was increased during the first weeks of treatment in males of groups 4 (1000 ppm) and 5 (5000 ppm). As from week 25 up to week 123 (last measurement) relative water consumption in these dose groups was similar to that of the control males. Females of group 5 (5000 ppm) had increased relative water consumption in comparison with the control group during the pretest period as well as during the treatment period. This finding was considered to be caused by the reduced mean body weights noted in the females at this dose level (see above) and was not considered to be test article related. Males of groups 2 (40 ppm) and 3 (200 ppm) and females of groups 2 (40 ppm), 3
(200 ppm) and 4 (1000 ppm) had similar relative water consumption to that of the respective controls throughout the treatment period.

OPHTHALMOSCOPIC EXAMINATION
Up to and including the highest dose level of 5000 ppm, no treatment related effects were noted in both male and female animals at ophthalmoscopic examinations.

HAEMATOLOGY
The assessment of hematological data indicated a few changes with statistical significance during the course of the treatment. The effects noted were most obvious in the rats of group 5 (5000 ppm) and were as follows:
-slightly lower erythrocyte count by 7 to 8 % on average for females at 26 and 52 weeks (a slight decrease by 8 % was also noted at 104 weeks, however, the finding did not achieve statistical significance);
-slightly lower hemoglobin concentration by 7 % on average for females at 26 weeks, by 3 to 7 % for both sexes at 52 weeks and by 10 % for females at
104 weeks (a slight decrease by 4 % was also noted for females of group 4 (1000 ppm) at 26 weeks);
-slightly lower hematocrit value by 4 to 3 % on average for females at 26 and 52 weeks;
-slightly higher mean corpuscular volume (MCV) by 5 % on average for females at 52 weeks;
-slightly lower mean corpuscular hemoglobin concentration (MCHC) by 2 to 4 % on average for both sexes at 26 and 52 weeks and by 5 % for females at 104 weeks (a slight decrease by 2 to 4 % was also noted for females of group 4 at 52 and 104 weeks);
-Higher reticulocyte count (relative and absolute) by 40 to 52 % on average for both sexes at 26 weeks, by 13 to 10 % for males and 42 to 30 % for females at 52 weeks, by 24 to 32 % for both sexes at 78 weeks, and 72 to 44 % for females at 104 weeks. In addition, a slight increase by 14 to 16 % on average was noted for males of group 4 at 26 weeks and by 92 to 69 % at 104 weeks.

The findings noted were considered treatment-related and suggest slight anemia with an increase in hemopoietic activity as indicated by the increase in reticulocytes. Furthermore, there was no effect on differential blood counts after 123 weeks of treatment. All other differences in the results of the hematology parameters were considered to be incidental or unrelated to the treatment and of normal biological variation for rats of this strain and age.

CLINICAL CHEMISTRY
For clinical biochemistry data there were no changes of toxicological significance during the course of the treatment. The only change of note was a
slight decrease in the total bilirubin concentration by 11 % on average for males of group 5 (5000 ppm) at 26 weeks, by 21 to 24 % for both sexes at 52 weeks and by 30 to 34 % for both sexes at 78 weeks. A slight decrease by 26 to 28 % was also noted for females of group 4 (1000 ppm) at 52 and 78 weeks. For the direct bilirubin concentration, a slight decrease by 24 to 20 % on average was noted for both sexes of groups 4 and 5 at 52 weeks and by 28 to 33 % for females of groups 4 and 5 at 78 weeks. The lower bilirubin concentrations were not considered of toxicological significance but more likely an expression of the functional activity of reticuloendothelial cells (bilirubin production) and hepatic cell function (bilirubin removal).
All other differences in the results of the clinical biochemical parameters were considered to be incidental or unrelated to the treatment and of normal biological variation for rats of this strain and age.

URINALYSIS
For urinalysis data the following effects were recorded in the rats of groups 4 (1000 ppm) and/or 5 (5000 ppm) during the course of the treatment:
-Decreased gamma-glutamyltransferase, alkaline phosphatase, leucine aminopeptidase and B-N-acetyl-D-glucosaminodase activity (females).
However, in contrast to the increase in urinary excretion of enzymes (enzymuria) which reflect lesional changes of renal tubuli, the biological significance of the above changes - slightly reduced urinary enzyme excretion - of membrane bound and lysosomal enzymes remains doubtfully, particularly in the absence of any other measurable biochemical abnormality and any histological correlate.

ORGAN WEIGHTS
No treatment related effects on the organ weights of the animals were noted in all dose groups. The statistically significant differences noted were considered to be incidental or for the group 5 (5000 ppm) females to correlate with the slightly reduced terminal body weight.

GROSS PATHOLOGY
A number of gross lesions were observed in the rats that died during the course of the study and in those that were sacrificed on schedule. The type, incidence, and severity of these gross lesions did not distinguish treated rats from controls.

HISTOPATHOLOGY: NON-NEOPLASTIC
A number of non-neoplastic lesions were diagnosed. The type, incidence, severity and organ distribution of these non-neoplastic changes did not distinguish treated rats from controls.
The non-neoplastic lesions were primarily inflammatory, degenerative, and/or hyperplastic changes. These lesions mainly affected the endocrine, reproductive, and large parenchymatous organs.

HISTOPATHOLOGY: NEOPLASTIC (if applicable)
A number of neoplastic lesions were diagnosed in the rats at scheduled and unscheduled necropsy. The type, incidence, severity and organ distribution were considered to be similar in both treated and control rats. The same was true for the number of primary neoplasms, the number of rats with more than one primary neoplasm, the number of rats with metastases, and the number of benign and malignant neoplasms per dose group and sex.

HISTORICAL CONTROL DATA (if applicable)
All other differences in the results of the hematology parameters apart from those thought to be treatment-related were considered to be incidental or unrelated to the treatment and of normal biological variation for rats of this strain and age.

Effect levels

1

Key result

Dose descriptor:

NOEL

Remarks:

systemic

Effect level:

200 ppm

Based on:

test mat.

Sex:

male/female

Basis for effect level:

other: no effect observed

Remarks on result:

other: corresponding to 9.80 and 12.07 mg/kg bw/day for males and females, respectively.

2

Key result

Dose descriptor:

NOAEL

Remarks:

systemic

Effect level:

1 000 ppm

Based on:

test mat.

Sex:

male/female

Basis for effect level:

other: no observed adverse effect

Remarks on result:

other: corresponding to 48.47 and 59.98 mg/kg bw/day for males and females, respectively.

3

Key result

Dose descriptor:

LOAEL

Remarks:

systemic

Effect level:

5 000 ppm

Based on:

test mat.

Sex:

male/female

Basis for effect level:

clinical biochemistry

Remarks on result:

other: corresponding to 251.60 and 317.96 mg/kg bw/day for males and females, respectively.

4

Key result

Dose descriptor:

NOAEL

Remarks:

carcinogenicity

Effect level:

5 000 ppm

Based on:

test mat.

Sex:

male/female

Basis for effect level:

other: no observed adverse effect

Remarks on result:

other: corresponding to 251.60 and 317.96 mg/kg bw/day for males and females, respectively.

Remarks:

highest dose tested

Target system / organ toxicity

Key result

Critical effects observed:

not specified

Any other information on results incl. tables

Table1: Distribution of unscheduled deaths:

	Number of unscheduled deaths		Survival (Kaplan-Meier Estimate)
Concentration (ppm)	Males	Females	Males	Females
0	25	30	60 %	49 %
40	29	33 (A)	53 %	49 %
200	29	33	53 %	43 %
1000	32	29	48 %	55 %
5000	22	32	65 %	47 %

(A) = One female died during anaesthesia

Table 2: Test article intake:

	Average test article intake up to 52 weeks (mg/kg/day)
Concentration (ppm)	Males	Females
40	1.92	2.38
200	9.80	12.07
1000	48.47	59.98
5000	251.60	317.96

Conclusion:

Based on the results obtained in this study, the "No observed effect level" (NOEL) of HOE 107892 SUBSTANCE TECHNICAL in the rat was considered to be 200 ppm in the diet, corresponding to an average daily intake of 9.80 mg/kg for males and 12.07 mg/kg for females. In consideration that the findings in the clinical biochemistry investigations expressed physiological-functional changes the "No observed adverse effect level" (NOAEL) was considered to be 1000 ppm in the diet, corresponding to an average daily intake of 48.47 mg/kg for males and 59.98 mg/kg for females. Up to and including the highest dietary concentration of 5000 ppm, there was no indication of any oncogenic potential of the test article.