Registration Dossier

Diss Factsheets

Administrative data

Description of key information

For repeated dose toxicity following study results are available for 3-Methylpyrazole:

1. 28-day sub-acute oral toxixity in mice: No NOAEL was identified based on adverse effects in the lung

2. 90-day sub-chronic oral toxicity in rats: NOAEL: 40 mg/kg

3. 90-day sub-chronic oral toxicity in mice: NOAEL: female: 5.31 mg/kg, male: 5.2 mg/kg

4. chronic toxicity (18 month) in rats: NAEL: 0.7 mg/kg based on liver alterations

5. Supporting: 90-day sub-chronic oral toxicity in rats: NOEL: 2 mg/kg

6. Supporting: 4-weeks lung toxicity study in mice: lung toxicity observed at all concentrations tested (900, 1125, 1575 ppm drinking water)

7. 2-week palatability study in mice: no effects observed at all concentrations tested (225, 675 ppm drinking water)

Key value for chemical safety assessment

Toxic effect type:
dose-dependent

Repeated dose toxicity: via oral route - systemic effects

Link to relevant study records

Referenceopen allclose all

Endpoint:
sub-chronic toxicity: oral
Type of information:
experimental study
Adequacy of study:
key study
Study period:
1998-07-21 - 2000-01-07
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
other: GLP-study
Qualifier:
according to guideline
Guideline:
OECD Guideline 408 (Repeated Dose 90-Day Oral Toxicity Study in Rodents)
Deviations:
no
GLP compliance:
yes (incl. QA statement)
Limit test:
no
Species:
mouse
Strain:
B6C3F1
Sex:
male/female
Route of administration:
oral: drinking water
Vehicle:
water
Details on oral exposure:
To achieve the target dose levels the test article concentrations in the water were adjusted weekly according to mean water consumption and mean body weight of the animals.
Analytical verification of doses or concentrations:
yes
Details on analytical verification of doses or concentrations:
Samples for the determination of the concentration, homogeneity and stability of the test article mixtures were drawn from the first test article preparations. Intercurrent samples for the determination of the concentration were drawn twice during the study, at monthly intervals. All samples were stored at room temperature prior to analysis by RCC Ltd, Environmental Chemistry and Pharmanalytics Division, CH-4452 Itingen by HPLC.
Duration of treatment / exposure:
13 weeks
Dose / conc.:
5 mg/kg bw (total dose)
Remarks:
Doses / Concentrations:
5 mg/kg
Basis:
nominal in water
Dose / conc.:
10 mg/kg bw (total dose)
Remarks:
Doses / Concentrations:
10 mg/kg
Basis:
nominal in water
Dose / conc.:
20 mg/kg bw (total dose)
Remarks:
Doses / Concentrations:
20 mg/kg
Basis:
nominal in water
Dose / conc.:
40 mg/kg bw (total dose)
Remarks:
Doses / Concentrations:
40 mg/kg
Basis:
nominal in water
No. of animals per sex per dose:
10 animals per sex and dose group
Control animals:
yes, concurrent no treatment
Positive control:
no
Observations and examinations performed and frequency:
Observations:

Clinical signs: At least once daily

Viability/mortality: Twice daily

Food consumption: Weekly

Water consumption: Weekly

Body weights: Weekly

Ophthalmoscopic examinations: Pretest: on all mice per sex and group.
At week 13: control and high dose animals.
At week 17: control and high dose animals.
After the application of a mydriatic solution (CIBA Vision AG, 3172 Niederwangen / 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) and the results were recorded. Unless otherwise indicated in the table, the contralateral eye was without abnormalities.

Sacrifice and pathology:
All animals were weighed and necropsied. Descriptions of all macroscopic abnormalities were recorded. 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 will be anesthetized by intraperitoneal injection of sodium pentobarbitone and killed by exsanguination.

Samples of the following tissues and organs will be collected from all animals at necropsy and fixed in neutral phosphate buffered 4% formaldehyde solution:
Adrenal glands

Aorta

(Auricles)

Bone marrow (femur)

Brain - including section of medulla/pons,

cerebral and cerebellar cortex

Cecum

Colon

Duodenum

Epididymides

Esophagus

(Exorbital lacrymal glands)

Eyes with optic nerve and Harderian gland

Femur - including articular surface

Heart

Ileum

Jejunum

Kidneys

Liver with gall bladder Lungs, infused with formalin Lymph nodes - mesenteric, mandibular Mammary gland area
Nasal cavity Ovaries Pancreas Pituitary gland Prostate gland Rectum

Salivary glands - mandibular, sublingual

Sciatic nerve

Seminal vesicles

Skeletal muscle

Skin

Spinal cord - cervical, midthoracic, lumbar Spleen

Sternum with bone marrow

Stomach

Testes

Thymus

Thyroid gland / parathyroid gland Trachea

Urinary bladder, infused with formalin

Uterus

Vagina

All gross lesions
Other examinations:
Blood samples for hematology and clinical biochemistry were collected from all allocation A animals at 13 weeks and from all allocation B animals at 17 weeks under light ether anesthesia. The animals were fasted for approximately 18 hours before blood sampling but allowed access to water ad libitum. Blood samples were collected early in the working day between the hours of 06.00 and 08.35 to reduce biological variation caused by circadian rhythms. Blood samples were drawn from the retro-orbital plexus using a micro-hematocrit glass capillary tube.
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
Food efficiency:
not examined
Water consumption and compound intake (if drinking water study):
effects observed, treatment-related
Description (incidence and severity):
Water consumption over treatment was marginally increased in females of groups 4 (20 mg/kg) and 5 (40 mg/kg) and slightly increased in males of groups 2 (5 mg/kg), 3 (10 mg/kg), 4 (20 mg/kg) and 5 (40 mg/kg).
Ophthalmological findings:
no effects observed
Haematological findings:
no effects observed
Clinical biochemistry findings:
no effects observed
Urinalysis findings:
not examined
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:
effects observed, treatment-related
Description (incidence and severity):
The Clara cell alteration noted in mice of groups 10, 20, and 40 mg/kg following the treatment period is considered to represent a mixed degenerative and regenerative process indicating a probable systemic effect of the test article.
Key result
Dose descriptor:
NOAEL
Effect level:
5 mg/kg bw/day (actual dose received)
Based on:
test mat.
Sex:
male/female
Basis for effect level:
other: toxicological endpoint: effects on Clara cells (lung)
Key result
Critical effects observed:
yes
Lowest effective dose / conc.:
10 mg/kg bw (total dose)
System:
respiratory system: lower respiratory tract
Organ:
lungs
Treatment related:
yes
Conclusions:
Based on these results the "no-observed-adverse-effect level (NOAEL)" in this study is considered to be the target dose of 5 mg/kg body weight/day corresponding to a test article intake of 5.20 mg/kg body weight/day in male mice and 5.31 mg/kg body weight/day in female mice.

The dose of 10 mg/kg/day is considered to represent a threshold dose level for the Clara cell alteration, since the incidence and severity of this lesion were substantially lower at this dose level when compared with the higher doses.
Executive summary:

Treatment of SPF-bred Crl:B6C3Fl mice with MP (3-Methylpyrazole) via their drinking water for a period of 13 weeks at doses of 5, 10, 20 or 40 mg/kg had no effect on survival, clinical signs, food consumption, body weight, ophthalmoscopy findings, hematology and clinical biochemistry parameters, organ weights or macroscopical findings. The increased water consumption noted in females of groups 4 (20 mg/kg) and 5 (40 mg/kg) as well in all male groups treated with MP reversed during the 4-week treatment-free recovery period and might reflect impaired palatability of the water by the test article resulting in undetected water spillage. The only other findings observed in this study were confined to histopathology. The Clara cell alteration noted in mice of groups 3 (10 mg/kg), 4 (20 mg/kg), and 5 (40 mg/kg) following the treatment period is considered to represent a mixed degenerative and regenerative process indicating a probable systemic effect of the test article. This Clara cell alteration was dose-dependent in incidence and severity in the groups affected. At the end of the treatment-free recovery period, Clara cell regeneration and repair were noted in association with a persistent Clara cell alteration. The 4-week treatment-free recovery period was insufficient to allow for full reversal of this Clara cell alteration. However the incidence and mean severity of this alteration showed a dose-related decrease in the recovery mice when compared with the mice sacrificed at termination of the treatment period. No Clara cell alterations were noted in mice of group 2 (5 mg/kg). Based on these results the "no-observed-adverse-effect level (NOAEL)" in this study is considered to be the target dose of 5 mg/kg body weight/day corresponding to a test article intake of 5.20 mg/kg body weight/day in male mice and 5.31 mg/kg body weight/day in female mice. The dose of 10 mg/kg/day is considered to represent a threshold dose level for the Clara cell alteration, since the incidence and severity of this lesion were substantially lower at this dose level when compared with the higher doses.

Based on the publications of the German MAK commission for napthalene ( see http://onlinelibrary.wiley.com/doi/10.1002/3527600418.mb9120d0021/full) and of the German Federal Environmental Agency (see http://www.umweltbundesamt.de/gesundheit/publikationen/ad-hoc/Naphthalin.pdf) clara cells of mice are considered to have a specific sensitivity to lung toxicants, because they have a cytochrome P450 dependent oxidation potency, which is 1 to 2 magnitudes higher as of humans (see also Buckpitt A. et al., Relationship of cytochrome P450 activity to Clara cell cytotoxicity. IV. Metabolism of naphthalene and naphthalene oxide in microdissected airways from mice, rats, and hamsters. , http://www.ncbi.nlm.nih.gov/pubmed/7838135). This means, that effects on clara cells of mice are not transferable to man a priori.

Endpoint:
chronic toxicity: oral
Type of information:
experimental study
Adequacy of study:
supporting study
Study period:
1985
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: In the highest dose group the test substance was not administered at a constant level during the whole study period. The dose level was changed from 2,000 to 1,000 ppm.
Qualifier:
no guideline followed
GLP compliance:
no
Limit test:
no
Species:
rat
Strain:
Wistar
Sex:
male/female
Route of administration:
oral: drinking water
Vehicle:
unchanged (no vehicle)
Analytical verification of doses or concentrations:
no
Duration of treatment / exposure:
18 months
Dose / conc.:
10 ppm
Remarks:
Doses / Concentrations:
10 ppm
Basis:
nominal in water
Dose / conc.:
40 ppm
Remarks:
Doses / Concentrations:
40 ppm
Basis:
nominal in water
Dose / conc.:
1 000 ppm
Remarks:
Doses / Concentrations:
2000 pmm (week 1-4), 1000 ppm (week 5-80)
Basis:
nominal in water
No. of animals per sex per dose:
32 male and 32 female animals per dose group
Control animals:
yes, concurrent no treatment
Clinical signs:
effects observed, treatment-related
Description (incidence and severity):
1000 ppm group
Mortality:
mortality observed, treatment-related
Description (incidence):
1000 ppm group
Body weight and weight changes:
effects observed, treatment-related
Description (incidence and severity):
1000 ppm group
Food consumption and compound intake (if feeding study):
effects observed, treatment-related
Description (incidence and severity):
1000 ppm group
Food efficiency:
not specified
Water consumption and compound intake (if drinking water study):
effects observed, treatment-related
Description (incidence and severity):
1000 ppm group
Haematological findings:
effects observed, treatment-related
Description (incidence and severity):
1000 ppm group
Clinical biochemistry findings:
effects observed, treatment-related
Description (incidence and severity):
40 and 1000 ppm group
Organ weight findings including organ / body weight ratios:
effects observed, treatment-related
Description (incidence and severity):
1000 ppm group
Gross pathological findings:
effects observed, treatment-related
Description (incidence and severity):
1000 ppm group
Histopathological findings: non-neoplastic:
no effects observed
Details on results:
Body weight:
10 and 40 ppm: No effects on body weight change were observed.
1000 ppm: Decreased body weights (males 82.3%, females 70.6 % of control group)

Food and water consumption:
10 and 40 ppm: no effects.
1000 ppm: Decreased water and food consumption.

Clinical signs:
All treatment and control group: Dyspnoea, cachexia, pneumonia

Mortality: cumulative death in the 1000 ppm group

Red blood cell count:
10 and 40 ppm: no effects
1000 ppm: Decrease of erythrocytes, decrease of haemoglobin and haematocrit

Clinical chemistry:
10 ppm: no effects
40 and 1000 ppm: Increase of aminotransferase, leucine aminopeptidase and alkaline phosphatase, inhibition of activity of cholinesterase (female only), decrease of gamma globulins, increase of cholesterol

Organ weights:
10 and 40 ppm: no effects
1000 ppm: Increased weight of heart, liver, kidney brain and thyroid

Histopathology:
10 and 40 ppm: no effects
1000 ppm: focal alterations in the liver

Ovaries: no effects on follicular maturation and evolution of corpus luteum

Testis: no effects on spermiogenesis
1000 ppm
Key result
Dose descriptor:
NOAEL
Effect level:
0.7 mg/kg bw (total dose)
Based on:
test mat.
Sex:
male/female
Basis for effect level:
haematology
mortality
Key result
Critical effects observed:
yes
Lowest effective dose / conc.:
10 ppm
System:
hepatobiliary
Organ:
liver
Treatment related:
yes
Conclusions:
Under the described conditions of the test the no adverse effect level of
3-Methylpyrazol is 0.7 mg/kg body weight per day (10 ppm; male and female). The revrsibility of the effects is not documented.
Executive summary:

Under the described conditions of the test, the no adverse effect level of 3-Methylpyrazol is 0.7 mg/kg body weight per day (10 ppm; male and female).

Endpoint:
repeated dose toxicity: oral
Remarks:
other: 2 weeks
Type of information:
experimental study
Adequacy of study:
supporting study
Study period:
not stated
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: Study is used as supporting study. No purity of test substance and several details of study performance are given.
Qualifier:
no guideline followed
GLP compliance:
no
Limit test:
no
Species:
mouse
Strain:
B6C3F1
Sex:
male/female
Route of administration:
oral: drinking water
Vehicle:
unchanged (no vehicle)
Analytical verification of doses or concentrations:
no
Duration of treatment / exposure:
2 weeks
Frequency of treatment:
daily
Dose / conc.:
173 mg/kg bw (total dose)
Remarks:
females
Dose / conc.:
140 mg/kg bw (total dose)
Remarks:
males
Dose / conc.:
61 mg/kg bw (total dose)
Remarks:
females
Dose / conc.:
47 mg/kg bw (total dose)
Remarks:
males
No. of animals per sex per dose:
3 males and 3 females per dose group
Control animals:
yes, concurrent no treatment
Observations and examinations performed and frequency:
Water consumption and body weights were determined each week. The animals were examined for signs of toxicity or mortality once a day. At the end of the 2-week administration period, all animals were subjected to gross-pathological assessment.
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):
not examined
Water consumption and compound intake (if drinking water study):
no effects observed
Ophthalmological findings:
not examined
Haematological findings:
not examined
Clinical biochemistry findings:
not examined
Urinalysis findings:
not examined
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
Key result
Dose descriptor:
NOAEL
Effect level:
173 mg/kg bw (total dose)
Based on:
test mat.
Sex:
female
Basis for effect level:
other: no effects observed
Key result
Dose descriptor:
NOAEL
Effect level:
140 mg/kg bw (total dose)
Based on:
test mat.
Sex:
male
Basis for effect level:
other: No substance-related effects were observed.
Conclusions:
In this palatabilty study, no substance related effects were observed.
Executive summary:

3 -Methylpyrazol was administered to groups of 3 male and 3 female mice in drinking water at concentrations of 0, 225 and 675 ppm for 2 weeks.

No substance related effects, concerning clinical signs, body weights and pathology, were observed.

Endpoint:
short-term repeated dose toxicity: oral
Type of information:
experimental study
Adequacy of study:
key study
Study period:
1997-01-07 - 1997-09-23
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: No hematological and clinical biochemistry investigations were performed.
Qualifier:
according to guideline
Guideline:
EU Method B.7 (Repeated Dose (28 Days) Toxicity (Oral))
Deviations:
no
GLP compliance:
yes (incl. QA statement)
Limit test:
no
Species:
mouse
Strain:
B6C3F1
Sex:
male/female
Details on test animals or test system and environmental conditions:
Mouse B6C3F1 Cri BR (SPF-Qua111y)
Recognised by international guidelines as the recommended test system (e.g. EPA, FDA, OECD, EEC). Females were nulliparous and non-pregnant.
Source : Charles River UK, Margate, Kent Approximately 6 weeks.
40 males, 40 females
Conditions
Air-conditioned room with approximately 15 air changes per hour and the environment controlled with optimal conditions considered as being a temperature of 21°C and a relative humidity of 50%. Fluctuations from these optimal conditions were noted, but were considered not to have affected study integrity. Lighting was 12 hours artificial fluorescent light and 12 hours dark per day.
Accommodation
Animals were housed individually in labelled MacroIon plastic cages with sterilised sawdust (B.M.I. Helmond, The Netherlands) provided as bedding. Certificates of analysis of the bedding are examined and archived.
Acclimatisation period was at least 5 days before start of treatment under laboratory conditions.
Diet
Free access to standard pelleted laboratory animal diet (from Carfil Quality BVBA, Oud-Turnhout, Belgium). Each batch is analysed for nutrients and contaminants are analysed on a regular basis. Results are examined and archived.
Water
Free access to tap-water during the pretest period and recovery period.
Free access to the control or test substance formulations in tap-water during the treatment period.
Certificates of analysis (performed quarterly) were examined and archived.
Route of administration:
oral: drinking water
Vehicle:
water
Details on oral exposure:
Free access to tap-water during the pretest period and recovery period. Free access to the control or test substance formulations in tap-water during the treatment period.
Certificates of analysis (performed quarterly) were examined and archived. Oral administration ad 1ibitum via the drinking water for at least 28 days. The day of first application is defined as Day 1. Animals were treated with the test substance up to the day of planned necropsy after 4 weeks.
Twice weekly the test formulations were changed.
Analytical verification of doses or concentrations:
yes
Details on analytical verification of doses or concentrations:
Test substance formulations in tap-water were noted as stable for at least 100 hours. Analysis of the accuracy of dose preparations revealed overall mean values of 92, 100 and 99 % of the nominal concentration for 300, 900 and 1575 ppm formulations. This was considered to represent an acceptable level of accuracy for formulations of this type.
Duration of treatment / exposure:
Oral administration ad 1ibitum via the drinking water for at least 28 days. The day of first application is defined as Day 1.
Dose / conc.:
70 mg/kg bw/day (actual dose received)
Remarks:
males
Dose / conc.:
82 spores/kg bw/day (actual dose received)
Remarks:
females
Dose / conc.:
151 mg/kg bw/day (actual dose received)
Remarks:
males
Dose / conc.:
193 mg/kg bw/day (actual dose received)
Remarks:
females
Dose / conc.:
223 mg/kg bw/day (actual dose received)
Remarks:
males
Dose / conc.:
252 mg/kg bw/day (actual dose received)
Remarks:
females
No. of animals per sex per dose:
5 males and 5 females per dose level
Control animals:
yes, concurrent no treatment
Details on study design:
The test substance was administered ad libitum in the drinking water for 28 days to SPF-bred B6C3F1 mice. One control group and three treated groups were tested, each consisting of 5 males and 5 females for termination after 28 days. An extra 5 animals per sex in all dose groups were allowed 14 days of recovery, The following parameters were evaluated:

clinical signs daily; body weight and food consumption weekly; water consumption twice weekly; macroscopy at termination; lung weights and histopathology of the lungs.
Positive control:
no
Observations and examinations performed and frequency:
Clinical signs At least once daily from day 1 onwards. The time of

onset, degree and duration were recorded. All symptoms were recorded and graded according to fixed scales:

Maximum grade 4: grading slight (1) to very severe (4).

Maximum grade 3: grading slight (1) to severe (3).

Maximum grade 1: presence is scored (1).
Sacrifice and pathology:
PATHOLOGY

NECROPSY

Animals were not fasted prior to necropsy.

All animals of the main groups surviving the application period, and all animals of the recovery groups surviving at least 14 days after the end of the application period, were deeply anaesthetised using ether vapour and subsequently exsanguinated. All animals assigned to the study were necropsied and descriptions of all macroscopic abnormalities recorded.

Samples of the following tissues and organs were collected from all animals at necropsy and fixed in neutral phosphate buffered 4% formaldehyde solution:

Adrenal glands

Aorta

Brain

Caecum

Cervix

Clitoral gland Colon Duodenum Epididymides

Eyes with optic nerve and Harderian gland Female mammary gland area Femur including joint
Heart

Ileum

Jejunum

Kidneys

Larynx

Lacrimal gland, exorbital

Liver with gall bladder

Lung, infused with formalin

Lymph nodes - mandibular, mesenteric

Nasopharynx

Oesophagus

Ovaries

Pancreas

Pituitary gland

Preputial gland

Prostate gland

Rectum

Salivary glands - mandibular, sublingual

Sciatic nerve

Seminal vesicles

Skeletal muscle

Skin

Spinal cord -cervical, midthoracic, lumbar Spleen

Sternum with bone marrow

Stomach

Testes

Thymus

Thyroid including parathyroid

Tongue

Trachea

Urinary bladder

Uterus

Vagina

All gross lesions

ORGAN WEIGHTS

The following organ weights (and terminal body weight) were recorded from the surviving animals on the scheduled day of necropsy:

Lungs (absol ute and relative weights are reported)

HISTOTECHNOLOGY

Lungs were processed, embedded and cut at a thickness of 2-4 micrometers and stained with haematoxylin and eosin.
HISTOPATHOLOGY

Slides were sent to Dr. med.vet. H.J. Chevalier, Experimental Pathology Services Ltd., Hauptstrasse 77a, CH-4132 Muttenz (Basel), Switzerland.

Lungs from all Main and Recovery animals were examined, with special emphasis on Clara cells. All abnormalities were described and included in the report.


Clinical signs:
effects observed, treatment-related
Description (incidence and severity):
Tremors and/or hunched posture were observed in up to 3 females treated with 900 or 1575 ppm of MP in the drinking water. Observations were recorded in the last half of the treatment period, and in some instances also in the recovery period.
Other findings noted among treated animals were considered not to be indicative of a treatment-related effect, but to remain within the range of biological variation for mice in this type of study.
Mortality:
no mortality observed
Body weight and weight changes:
effects observed, treatment-related
Description (incidence and severity):
A statistically significant decrease in body weight was noted for females receiving 1575 ppm after 4 weeks of treatment.
A statistically significant decrease in body weight gain was noted after 1 and 4 weeks of treatment for males receiving 1575 ppm, and after 2, 3 and 4 weeks of treatment for females of that dose group.
In females of the 900 ppm dose group, body weight gain was decreased after 4 weeks of treatment only.
During the recovery period, no differences in body weight gain were noted between control and treated groups.
Food consumption and compound intake (if feeding study):
effects observed, treatment-related
Description (incidence and severity):
Group mean food consumption values were decreased with statistical significance throughout the treatment period in males and females receiving 1575 ppm and females receiving 900 ppm.
Males treated with 900 ppm showed a decrease in food consumption in week 1 only.
Relative food consumption values showed the same tendency as described above. In addition, females receiving 300 ppm also showed a decrease in relative food consumption in week 4.
During the recovery period, no differences in (relative) food consumption were noted between control and treated groups, with the exception of a low value for food consumption in 1575 ppm treated females in the first week of recovery.
Food efficiency:
not examined
Water consumption and compound intake (if drinking water study):
effects observed, treatment-related
Description (incidence and severity):
Water consumption in ml/animal/day was decreased with statistical significance throughout the treatment period in both males and females of the 900 ppm and 1575 ppm dose groups.
In addition, water consumption was decreased in females receiving 300 ppm in week 2 of treatment.
During recovery, normal water consumption was noted among all groups.
The test substance intake was calculated from the water consumption, nominal test substance concentration in the drinking water and body weight values. Mean values for males and females respectively over the study period were calculated to be as follows:
Group 2: 70 and 82 mg/kg body weight/day
Group 3: 151 and 193 mg/kg body weight/day
Group 4: 223 and 252 mg/kg body weight/day

Ophthalmological findings:
not examined
Haematological findings:
not examined
Clinical biochemistry findings:
not examined
Endocrine findings:
not examined
Urinalysis findings:
not examined
Behaviour (functional findings):
not examined
Immunological findings:
not examined
Organ weight findings including organ / body weight ratios:
effects observed, treatment-related
Description (incidence and severity):
At the 4-week terminal sacrifice, the mean absolute lung weights were increased in the females of the 900 and 1575 ppm groups, while the mean organ-body weight ratios of the lungs were increased in males of the 900 and 1575 ppm groups, and in females of the 300, 900 and 1575 ppm groups.
At the 6-week sacrifice after the recovery period, the mean absolute lung weight was increased in females of the 900 ppm group, while the mean organ-body weight ratios were increased in females of the 900 and 1575 ppm groups.

Gross pathological findings:
effects observed, treatment-related
Description (incidence and severity):
Macroscopic observations at necropsy did not reveal any alterations that were considered to have arisen as a result of treatment.
Findings noted among treated and/or control animals included a reduced size of the kidneys and enlargement of the iliac or bronchial lymph nodes. These findings were considered to be within the range of biological variation for mice of this age and strain and not to represent a change of toxicological significance.
Neuropathological findings:
not examined
Histopathological findings: non-neoplastic:
effects observed, treatment-related
Description (incidence and severity):
At the end of the 4-week treatment period, Clara cell alteration was noted in all treated mice. This alteration was moderate in the 300 and 900 ppm groups, and moderate to marked in the 1575 ppm group. This change was characterised by a loss of the characteristic dome-shaped appearance and the apical ’bleb’, by cytokaryomegaly, and basophilia. In addition, mitotic figures and/or macrophages were noted in this altered epithelium in mice of the 1575 ppm group. This alteration involved bronchi and bronchioli, but was more prominent in the bronchioli.
In a few mice of the 900 and 1575 ppm groups, interstitial histiocytosis, alveolar macrophages, alveolar hemorrhage, alveolar edema, and/or interstitial edema/congestion were noted, in addition. The severity of these changes was mainly siight.
At the end of the recovery period, Clara cell alteration was noted in all treated mice. This alteration was slight to moderate in the 300 and 900 ppm groups, and moderate to marked in the 1575 ppm group. In addition, slight to moderate Clara cell proliferation was noted in all treated mice. This change was characterised by increased numbers of the afore-mentioned cytokaryomegalic, basophilic, and sometimes multinuclear cells. In addition, these cells were arranged in two cell layers instead of the normal one layer. Mitotic figures were occasionally noted.
Alveolar macrophages were noted in one female of the 1575 ppm group, and alveolar hemorrhage was noted in one male each of the 900 and 1575 ppm groups.
Histopathological findings: neoplastic:
not examined
Key result
Dose descriptor:
LOAEL
Effect level:
82 mg/kg bw (total dose)
Based on:
test mat.
Sex:
female
Basis for effect level:
body weight and weight gain
gross pathology
histopathology: non-neoplastic
Key result
Dose descriptor:
LOAEL
Effect level:
70 mg/kg bw (total dose)
Based on:
test mat.
Sex:
male
Basis for effect level:
body weight and weight gain
gross pathology
histopathology: non-neoplastic
other: A morphologic no-effect level could not be established when mice were exposed to 3-MP in the drinking water for 28 days. Moreover, complete recovery of the alterations in the lungs was not accomplished in a 14 day follow-up period.
Key result
Critical effects observed:
yes
Lowest effective dose / conc.:
193 mg/kg bw/day (actual dose received)
System:
respiratory system: lower respiratory tract
Organ:
lungs
Treatment related:
yes
Dose response relationship:
not specified
Relevant for humans:
not specified
Conclusions:
A morphologic no-effect level could not be established when mice were exposed to MP in the drinking water for 28 days. Moreover, complete recovery of the alterations in the lungs was not accomplished in a 14 day follow-up period.

The actual intake of test substance was 70/82, 151/193 and 223/252 mg/kg body weight/day for males/females of the 300, 900 and 1575 ppm dose groups respectively.
Executive summary:

The study was based on the following guideline: EC Directive 96/54/EC, B.7 Repeated Dose (28 days) Toxicity (oral), 1996. The test substance was administered ad libitum in the drinking water for 28 days to SPF-bred B6C3F1 mice. One control group and three treated groups were tested, each consisting of 5 males and 5 females for termination after 28 days. An extra 5 animals per sex in all dose groups were allowed 14 days of recovery, The following parameters were evaluated: clinical signs daily; body weight and food consumption weekly; water consumption twice weekly; macroscopy at termination; lung weights and histopathology of the lungs.

Formulations:Accuracy and stability of test substance formulations were demonstrated by analyses.

The administration of MP via the drinking water to B6C3F1 mice at dose levels of 300, 900 and 1575 ppm did not result in treatment-related intercurrent deaths.

Clinically, effects included observations of tremors and hunched posture (females 900 and 1575 ppm), decreased body weights (males and/or females 900 and 1575 ppm), and decreased food and water consumption (males and females 900 and 1575 ppm).

At the 300 ppm dose level, the only effects noted were a slight and incidental decrease in food and water consumption of female mice.

Nearly all clinical effects reversed completely during the recovery phase.

Microscopic examination of the lungs revealed changes among all treated mice. The Clara cell alteration is considered to represent a mixed degenerative and regenerative process indicating a systemic toxic effect of the test substance. At the end of the recovery period, cell regeneration and repair were considered to be more pronounced, as indicated by Clara cell proliferation.

Since the parenchymal lung changes, i.e. interstitial histiocytosis, alveolar macrophages, alveolar hemorrhage, alveolar edema, and interstitial edema/ congestion, were only noted in mice of the 900 and 1575 ppm dose groups, they are considered to represent a slight treatment-related toxic injury and may correspond to the lung weight increase noted in the 900 and 1575 ppm dose groups.

The 2-week recovery period did not suffice for reversal of the treatment-related changes.

300 ppm:

1) Slight and incidental decrease in food and water consumption in females.

2)Increased lung weights in females.

3)Moderate Clara cell alteration in males and females.

900 ppm:

1) Tremors and hunched posture noted in females.

2)Decreased body weights noted in females. Decreased food and water consumption noted in males and females.

3)Increased lung weights in males and females.

4)Moderate Clara cell alteration in males and females. Parenchymal lung changes in a few mice.

1575 ppm:

1) Tremors and hunched posture noted in females.

2)Decreased body weights, food and water consumption noted in males and females.

3)Increased lung weights in males and females.

4)Moderate to marked Clara cell alteration in males and females. Parenchymal lung changes in a few mice.

CONCLUSION:

A morphologic no-effect level could not be established when mice were exposed to MP in the drinking water for 28 days. Moreover, complete recovery of the alterations in the lungs was not accomplished in a 14 day follow-up period. The actual intake of test substance was 70/82, 151/193 and 223/252 mg/kg body weight/day for males/females of the 300, 900 and 1575 ppm dose groups respectively.

Endpoint:
sub-chronic toxicity: oral
Type of information:
experimental study
Adequacy of study:
key study
Study period:
1998-05-29 - 1999-03-31
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
Qualifier:
according to guideline
Guideline:
OECD Guideline 408 (Repeated Dose 90-Day Oral Toxicity Study in Rodents)
Deviations:
no
Qualifier:
according to guideline
Guideline:
OECD Guideline 407 (Repeated Dose 28-Day Oral Toxicity Study in Rodents)
Deviations:
no
GLP compliance:
yes (incl. QA statement)
Limit test:
no
Species:
rat
Strain:
Wistar
Sex:
male/female
Route of administration:
oral: drinking water
Vehicle:
water
Details on oral exposure:
The dose was administered permanently via the drinking water, 7 days a week for 90 days as solution in tap water (municipal supply) adjusted to pH 5.5 with HC1.
Because the drinking water should be administered ad libitum, the concentration of the test article in the drinking water was adjusted according to the most recent mean drinking water consumption and the most recently weekly recorded mean body weight of all animals of the dose group, separated by sex.
Analytical verification of doses or concentrations:
yes
Details on analytical verification of doses or concentrations:
To determine actual concentrations, two samples each of the drinking water freshly prepared before put into bottles and after the two days administration period (mixing sample of all cages, separated by sex), prepared for use during week 1, 6 and 12 of dosing were taken and stored until analysis at -80 °C.
The amount of 3-Methylpyrazol in the formulation was analysed by HPLC.
Duration of treatment / exposure:
90 days
Frequency of treatment:
The dose was administered permanently via the drinking water, 7 days a week for 90 days as solution in tap water (municipal supply) adjusted to pH 5.5 with HC1.
Dose / conc.:
40 mg/kg bw (total dose)
Remarks:
Doses / Concentrations:
40 mg/kg
Basis:
nominal in water
No. of animals per sex per dose:
5 males and 5 females per dose group
Control animals:
yes, concurrent no treatment
Positive control:
no
Observations and examinations performed and frequency:
Clinical Observations

Ophthalmological examination, using a hand slitlamp (Heine OPTOTECHNIK), was made prior to the first administration of the test article and at the termination of the study in all animals.

A detailed clinical examination was carried out daily.

The following signs were given predominant consideration: changes in skin, fur, eyes, mucous membranes, gait, posture and response to handling; occurrence of secretions and excretions; autonomic activity, presence of clonic or tonic movements and stereotypies or bizarre behaviour.

Assessments of sensory reactivity (auditory, visual and proprioceptive stimuli), grip strength and motor activity were carried out prior to administration, at monthly intervals and in the last week of dosing and in the last week of the recovery period.

Mortality

Animals were examined daily for mortality and morbidity.

Body Weight

Body weights were recorded at the start of the study, then weekly thereafter and at the end of the administration and at the end of the recovery period in the animals of the satellite groups.

Drinking Water Consumption

Drinking water consumption was recorded every two days throughout the treatment and recovery period of each cage and group mean daily intakes per animal were calculated.

Calculation of realised mean daily intake of the test article in mg/kg body weight was made by means of the most recently weekly recorded individual body weights and drinking water consumption's.

Food Consumption

Food consumption was recorded weekly throughout the treatment and recovery periods and group mean daily intakes were calculated.
Sacrifice and pathology:
Pathology

All animals were killed at the end of the treatment or recovery period, respectively, by chloroform asphyxiation.

Macroscopic Pathology

All animals were examined externally. The cranial, thoracic and abdominal cavities were opened and examined macroscopically.

Organ Weights

The kidneys, liver and lungs of all animals were weighed after trimming off fat and other contiguous tissue.

The left and right kidney were weighed and reported separately.

Histology

The kidneys, liver and lungs and a tissue specimen of nasal mucosa of all animals were fixated in Formol-Alcohol* and preserved in 4 percent formaldehyde*.

The microscopic examination was made after staining using Hemalum-Eosin*. The nasal mucosa and the lung tissue were examined taking especially notice of Clara cells. Clara cells are characterised by following signs: Cuboidal to columnar and nonciliated cells with irregular, elongated nuclei varied in size and with deep nuclear folds and invagination; tubulary or papillary formed and by connective tissue septa separated adenomas which have not a true capsule but a clearly outlined borders of compressed tissue ("Respiratory System", T.C.Jones; U.Mohr; R.D.Hunt, Springer-Verlag Berlin Heidelberg New York Tokyo 1985).

Both kidneys were examined.

The fixated organs of the animals of the recovery satellite groups were not examined because pathological changes were not observed in the inspected organs of the treated animals killed at the end of the treatment period.
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
Food efficiency:
not examined
Water consumption and compound intake (if drinking water study):
effects observed, treatment-related
Description (incidence and severity):
A tendency for a decreased drinking water consumption was observed in all cases of the treated animals. This effect could be caused by the odour of the test article.
Ophthalmological findings:
no effects observed
Haematological findings:
not examined
Clinical biochemistry findings:
not examined
Urinalysis findings:
not examined
Behaviour (functional findings):
not examined
Organ weight findings including organ / body weight ratios:
effects observed, treatment-related
Description (incidence and severity):
The absolute and relative weights of the kidneys and of the liver were increased in the treated female animals The increased weights were no longer apparent at the end of the treatment-free recovery period.
Gross pathological findings:
no effects observed
Histopathological findings: non-neoplastic:
no effects observed
Histopathological findings: neoplastic:
not examined
Key result
Dose descriptor:
NOAEL
Effect level:
40 mg/kg bw/day (nominal)
Based on:
test mat.
Sex:
male/female
Basis for effect level:
other: reversible increased organ weights of the kidneys and the liver but fully reversible at the end of recovery
Key result
Critical effects observed:
no
Conclusions:
The daily oral administration of 3-Methylpyrazol at nominal doses of 40 mg/kg body weight via the drinking water to rats for a period of 90 days was tolerated without any marked effect.

Special histological attention was directed to epithelial cells but no signs of any adverse effects could be detected in the lungs as well as the nasal mucosa.
The reversible increased organ weights of the kidneys and the liver could be caused by a changed metabolism, but it does not cause any visible damage. The female animals react a little more sensitive than the male animals.
Executive summary:

The aim of the study was to provide information on the toxicity and reversibility of possible effects of the test article when administered by the oral route via drinking water to the rat, daily for 90 days with a 28 day treatment-free recovery period. A special issue of this study was to investigate the capacity of the test article to cause adverse effects to the nasal and lung epithelial cells under particular consideration of Clara cells.

Results:

None of the animals died during the course of investigation. No clinical symptoms were observed. None of the animals showed any alterations of their general state of well-being and behaviour at any observation period. Neither the body weights nor the food consumption of the animals were influenced by administration of the test article. The absolute and relative weights of the kidneys and of the liver were increased in the treated female animals The increased weights were no longer apparent at the end of the treatment-free recovery period. No pathological macroscopic findings were observed. No substance-dependent histopathological findings were observed.

Conclusion:

The daily oral administration of 3-Methylpyrazol at nominal doses of 40 mg/kg body weight via the drinking water to rats for a period of 90 days was tolerated without any marked effect. Special histological attention was directed to epithelial cells but no signs of any adverse effects could be detected in the lungs as well as the nasal mucosa. The planned nominal doses were well achieved. The reversible increased organ weights of the kidneys and the liver could be caused by a changed metabolism, but it does not cause any visible damage. The female animals react a little more sensitive than the male animals.

Endpoint:
short-term repeated dose toxicity: oral
Type of information:
experimental study
Adequacy of study:
supporting study
Study period:
1995-07-13 - 1996-02-08
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
other: GLP-study
Qualifier:
equivalent or similar to guideline
Guideline:
OECD Guideline 407 (Repeated Dose 28-Day Oral Toxicity Study in Rodents)
Deviations:
yes
Remarks:
no haematological investigations
GLP compliance:
yes (incl. QA statement)
Limit test:
no
Species:
mouse
Strain:
B6C3F1
Sex:
male/female
Route of administration:
oral: drinking water
Vehicle:
unchanged (no vehicle)
Analytical verification of doses or concentrations:
yes
Duration of treatment / exposure:
28 days
Frequency of treatment:
daily
Dose / conc.:
206 mg/kg bw (total dose)
Dose / conc.:
176 mg/kg bw (total dose)
Dose / conc.:
154 mg/kg bw (total dose)
Remarks:
Doses / Concentrations:
154, 176, 206 mg/kg body weight
Basis:
nominal in water
No. of animals per sex per dose:
5 males and 5 females per dose group
Control animals:
yes, concurrent no treatment
Observations and examinations performed and frequency:
Clinical observations:
-signs of toxicity or mortality twice a day
-comprehensive clinical examination once a week

Water consumption:
-weekly over a period of 4 days

Body weight:
-on day 0 (start of administration period) and thereafter at weekly intervals

PATHOLOGY:
Organ weights: liver, lungs, kidneys

Histopathology:
liver, lungs, kidneys, whole remaining animal body


Clinical signs:
no effects observed
Mortality:
no mortality observed
Body weight and weight changes:
effects observed, treatment-related
Description (incidence and severity):
impaired body weight change in the females
Food consumption and compound intake (if feeding study):
not examined
Water consumption and compound intake (if drinking water study):
effects observed, treatment-related
Description (incidence and severity):
impaired water consumption in both sexes
Ophthalmological findings:
not examined
Haematological findings:
not examined
Clinical biochemistry findings:
not examined
Urinalysis findings:
not examined
Behaviour (functional findings):
not examined
Organ weight findings including organ / body weight ratios:
effects observed, treatment-related
Description (incidence and severity):
increased mean absolute and relative lung weights, the latter without statistical significance in females
Histopathological findings: non-neoplastic:
effects observed, treatment-related
Description (incidence and severity):
karyomegaly in the epithelia of the air ducts of the lung (all animals), loss of domes in the Clara cells of the lung (all animals), hypotrophy of the air duct epithelia (all animals)
Key result
Dose descriptor:
NOAEL
Basis for effect level:
other: Clear signs of lung toxicity could be observed at all concentrations tested.
Remarks on result:
not determinable
Remarks:
no NOAEL identified
Key result
Critical effects observed:
yes
System:
respiratory system: lower respiratory tract
Organ:
lungs
Treatment related:
yes
Conclusions:
Clear signs of lung toxicity could be observed at all concentrations tested.
Executive summary:

3-Methylpyrazol was administered to groups of 5 male and 5 female B6C3F1 CrlBR mice in drinking water at concentrations of 0 ppm; 900 ppm; 1,125 ppm and 1,575 ppm over a period of 4 weeks. As clinical findings, an impairment of water consumption was seen dose-dependently in all treatment groups, and body weight change was impaired in high dose females. As a result of the impaired water consumption, the intended dose levels of 180, 225 and 315 mg/kg body weight, respectively, could not be achieved. Thus the actual, mean daily test substance intake was 154, 176 and 206 mg/kg body weight/day, only. Pathology revealed treatment related lesions in the lining epithelia of the air ducts from the main stem bronchi over the lobar and lobular bronchi to the terminal bronchioli of male and female mice at all dose levels tested. The lesions in the terminal bronchioles consisted of severe flattening or loss of the apical parts of the Clara cells (loss of domes) - thus loosing their cellular polarity - and of the development of irregularly formed Clara cells with large nuclei (karyomegaly). In the larger air ways, extending up into the main stem bronchi, the mucus producing cells show a comparable effect as the Clara cells in that their cell bodies are shrunken (hypotrophy), with no or inconspicuous amounts of mucus in the cytoplasm and considerably severe karyomegaly. As judged from the H.& E. stained slides, both lesions were not accompanied by an obvious cellular degeneration or necrosis, and in no case was there an indication for increased cell replication, viz. no mitoses could be detected, and there was no morphologic indication for cellular hyperplasia. On the contrary, the distorted and enlarged nuclei give raise to the suspicion that they may result from incomplete mitosis. It is astonishing that the morphologically severe alteration of mucus and surfactant production does not result in concomittant clinical or physiologic alterations. The importance of the minimal (grade 1) or slight (grade 2) focal histiocytosis - seen in each two female mice of dose groups 1 and 2 - is difficult to interpret. However, although this lesion was not seen in top dose female mice and in none of the treated males, it is regarded as a possibly treatment related effect, however, of marginal if any toxicologic relevance.

Endpoint:
sub-chronic toxicity: oral
Type of information:
experimental study
Adequacy of study:
key study
Study period:
1979-03-21 - 1979-06-14 (application period)
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: Administration of test substanece only 5 days per week, no post-administration observation
Qualifier:
equivalent or similar to guideline
Guideline:
OECD Guideline 408 (Repeated Dose 90-Day Oral Toxicity Study in Rodents)
Deviations:
not specified
Principles of method if other than guideline:
The study was perfomed in 1980 before implementation of validated guidelines in the German Democratic Republic
GLP compliance:
no
Limit test:
no
Species:
rat
Strain:
Wistar
Sex:
male/female
Route of administration:
oral: gavage
Vehicle:
water
Analytical verification of doses or concentrations:
no
Duration of treatment / exposure:
90 days
Frequency of treatment:
once daily, 5 days per week
Dose / conc.:
0.2 mg/kg bw/day (nominal)
Dose / conc.:
2 mg/kg bw (total dose)
Dose / conc.:
20 mg/kg bw (total dose)
Dose / conc.:
200 mg/kg bw (total dose)
No. of animals per sex per dose:
24 males and 24 females per dose group
Control animals:
yes, concurrent vehicle
Observations and examinations performed and frequency:
clinical signs, mortality: once daily
body weight, food consumption: weekly
haematology: 2., 3., 12. week
clinical chemistry: 2., 3., 12. week
24 and 48h; 2., 3., 12. week (ASAT, LAP, AP, ChE/Pl)
Sacrifice and pathology:
organ weights, macroscopic examinations, histopathology
Clinical signs:
effects observed, treatment-related
Description (incidence and severity):
hair loss (male and female) at 200 mg/kg; fragility of mandibular incisivi
Mortality:
mortality observed, treatment-related
Description (incidence):
hair loss (male and female) at 200 mg/kg; fragility of mandibular incisivi
Body weight and weight changes:
effects observed, treatment-related
Description (incidence and severity):
reduced body weight (male and female) at 200 mg/kg
Food consumption and compound intake (if feeding study):
effects observed, treatment-related
Description (incidence and severity):
reduced food consumption (male and female) at 200 mg/kg
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):
-decreased erythocytes, hematocrit and hemoglobin at 200 mg/kg (male and female), increased number of neutrophilic leucocytes at 200 mg/kg,
Clinical biochemistry findings:
effects observed, treatment-related
Description (incidence and severity):
slightly decreased total protein and albumin at 200 mg/kg, decreased glucose at 200 mg/kg, increased ASAT and LAP activity at 200 mg/kg, decreased ChE activity at 200 mg/kg (female)
Urinalysis findings:
no effects observed
Organ weight findings including organ / body weight ratios:
effects observed, treatment-related
Description (incidence and severity):
increased weight of liver, kidneys, adrenals, heart and brain at 200 mg/kg (male and female)
Gross pathological findings:
effects observed, treatment-related
Description (incidence and severity):
Nucleus anisomorphism, fatty degeneration and cell death of liver cells, alteration of thyroid glands
Histopathological findings: non-neoplastic:
effects observed, treatment-related
Description (incidence and severity):
liver: cell death and fatty degenerations
Key result
Dose descriptor:
NOAEL
Effect level:
20 mg/kg bw/day (nominal)
Based on:
test mat.
Sex:
male/female
Basis for effect level:
clinical signs
haematology
histopathology: neoplastic
Key result
Critical effects observed:
yes
Lowest effective dose / conc.:
200 mg/kg bw (total dose)
System:
hepatobiliary
Organ:
kidney
liver
thyroid gland
Treatment related:
yes
Dose response relationship:
not specified
Conclusions:
Under the described conditions of the test, the No-Effect-Level of 3-Methylpyrazol is 2 mg/kg body weight per day.
Executive summary:

3 -Methylpyrazol was tested for its sub-chronic toxicity in Wistar rats. The test substance was administered orally by gavage to male and female rats in doses of 0.2, 2, 20 and 200 mg/kg body weight. The control group was dosed with the vehicle only. The following findings were obtained and assessed as substance related:

-hair loss (male and female) at 200 mg/kg; fragility of mandibular incisivi (200 mg/kg)

- reduced body weight (male and female) at 200 mg/kg

- decreased erythocytes, hematocrit and hemoglobin (male and female), increased number of neutrophilic leucocytes at 200 mg/kg

- slightly decreased total protein and albumin at 200 mg/kg, decreased glucose at 200 mg/kg, increased ASAT and LAP activity at 200 mg/kg, decreased ChE activity at 200 mg/kg (female)

-increased weight of liver, kidneys, adrenals, heart and brain at 200 mg/kg (male and female)

- Nucleus anisomorphism, fatty degeneration and cell death of liver cells, alteration of thyroid glands

Based on these results, under the described study conditions, the No-effect-Level was 2 mg/kg body weight per day.

Endpoint conclusion
Endpoint conclusion:
adverse effect observed
Dose descriptor:
NOAEL
40 mg/kg bw/day
Study duration:
subchronic
Species:
rat
Quality of whole database:
The key study is GLP-compliant and has Klimisch score 1.
Organ:
kidney
liver

Repeated dose toxicity: inhalation - systemic effects

Endpoint conclusion
Endpoint conclusion:
no study available

Repeated dose toxicity: inhalation - local effects

Endpoint conclusion
Endpoint conclusion:
no study available

Repeated dose toxicity: dermal - systemic effects

Endpoint conclusion
Endpoint conclusion:
no study available

Repeated dose toxicity: dermal - local effects

Endpoint conclusion
Endpoint conclusion:
no study available

Additional information

Justification for classification or non-classification

From "Committee for Risk Assessment- RAC Opinion proposing harmonised classification and labelling at EU level of

3-methylpyrazol (citation):

"In one study in mice, effects were observed at a dose near the guidance value for STOT RE 1, but these effects occurred at lower incidences than in the higher dose groups and no club cell alterations were observed at the next lower dose level (5 mg/kg bw/d). Moreover, incidences and grades were lower in the recovery group, and proliferation of club cells was noted, indicating at least partial reversibility of the effect. In addition, no accompanying clinical signs were observed at 10 mg/kg bw/d. No details on the reported alterations were provided in the CLH report. Thus, RAC could not evaluate their severity. The observed effects are therefore considered not sufficient for classification as STOT RE 1. Effects in the two other studies were seen at dose levels clearly in the range of STOT RE 2 guidance values.

Given that effects seen at the upper limit of the guidance value for STOT RE 1 were not seen at the next lower dose level and were not supported by clinical signs, and since mice seem more prone to club cell effects compared to rats, RAC proposes in a weight of evidence approach to classify 3-methylpyrazole as STOT RE 2; H373 (lung).

The lung as target organ was only identified in a study with mice, but not with rats. This means, that a specific target toxicity to humans is not likely."

Therefore 3 -methylpyrazole has to be classified as STOT RE 2; H373 (lung).