Cyclopentane, methoxy-

Repeated dose toxicity: inhalation

Administrative data

Endpoint:

sub-chronic toxicity: inhalation

Type of information:

experimental study

Adequacy of study:

key study

Study period:

17 February 2004 - 14 September 2004

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: The study was performed according to OECD test guidelines, and in compliance with GLP, so the data is considered reliable without restrictions.

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2004

Report date:

2004

Materials and methods

Test guideline

Qualifier:

according to guideline

Guideline:

OECD Guideline 413 (Subchronic Inhalation Toxicity: 90-Day Study)

Deviations:

no

GLP compliance:

yes

Limit test:

no

Test material

Test material information

Constituent 1

Reference substance name:

-

EC Number:

445-090-6

EC Name:

-

Cas Number:

5614-37-9

Molecular formula:

C6 H12 O

IUPAC Name:

Cyclopentyl methyl ether

Test material form:

liquid

Specific details on test material used for the study:

- Analytical purity: 99.93%
- Lot/batch No.: 3700546

Test animals

Species:

rat

Strain:

Crj: CD(SD)

Sex:

male/female

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Age at study initiation: Five weeks
- Weight at study initiation:Males: 141 - 174 g; Additional males: 158 - 181 g; females 132 - 152 g
- Housing: Autoclaved polycarbonate cages, replaced once per week after the start of the administration period. Animals were housed in groups of 3 or fewer during the acclimatisation period, and two per cage during the administration period.
- Diet (e.g. ad libitum): Ad libitum, except during the daily dosing period
- Water (e.g. ad libitum): Ad libitum, except during the daily dosing period
- Acclimation period: (Quarantine period) - 5 days

ENVIRONMENTAL CONDITIONS
- Temperature (°C): Permissable range: 19.0 - 25.0°C; actual range: 21.6 - 22.7°C
- Humidity (%): Permissable range: 35 - 75%; actual range: 51.3 - 64.4%
- Air changes (per hr): 6 to 20 (10 to 30 per hour during the quarantine period)
- Photoperiod (hrs dark / hrs light): 12 hours light per day

IN-LIFE DATES: From: 02 March 2004 To: 14 July 2004

Administration / exposure

Route of administration:

inhalation

Type of inhalation exposure:

whole body

Vehicle:

air

Remarks on MMAD:

MMAD / GSD: Not recorded

Details on inhalation exposure:

GENERATION OF TEST ATMOSPHERE / CHAMBER DESCRIPTION
- Exposure apparatus: Rectangular parallelpiped chamber, inner volume approximately 90 L.
- Source and rate of air: Compressed air, 20 L/min (c.a. 13 air changes per hour)
- System of generating particulates/aerosols: Test material was passed through nitrogen to generate a gas.
- Air flow rate: 20 L/min
- Air change rate: 13 air changes/hour
- Treatment of exhaust air: Diluted into external air after passing through a charcoal filter.

TEST ATMOSPHERE
- Brief description of analytical method used: Atmosphere samples collected through an impinger (solvent used: methanol). Samples were analysed by GC:FID

VEHICLE (if applicable)
- Justification for use and choice of vehicle: Test material was nebulised using Nitrogen. The test atmosphere was mixed with air prior to exposure to the test animals to achieve the appropriate test material concentration for exposure.

Analytical verification of doses or concentrations:

yes

Details on analytical verification of doses or concentrations:

Once a week, duplicate atmosphere samples were collected at 0.5, 3.0, and 5.5 hours during the exposure period. Samples were collected using an impinger (solvent = methanol) and analysed by GC-FID.

Duration of treatment / exposure:

6 hours

Frequency of treatment:

Five days per week for 13 consecutive weeks (total of 65 days' exposure).

Doses / concentrations

Doses / concentrations 1

Dose / conc.:

0 mg/L air

Doses / concentrations 2

Dose / conc.:

0.2 mg/L air

Doses / concentrations 3

Dose / conc.:

0.4 mg/L air

Doses / concentrations 4

Dose / conc.:

0.8 mg/L air

Doses / concentrations 5

Dose / conc.:

4 mg/L air

No. of animals per sex per dose:

Ten males and ten females per dose level. The control (0 mg/L) and high dose (4.0 mg/L) levels had an additional six males and six females which underwent a recovery period after the end of the dosing phase.

Control animals:

yes, concurrent vehicle

Details on study design:

- Dose selection rationale: A prior 14-day range-finding study was conducted at targeted concentrations 0.8, 4.0, and 20.0 mg/L. Lethal effects were seen in the 20.0 mg/L level; salivation, body weight change and increased white blood cell count were seen in the 4.0 mg/L level. As toxic effects could be expected at 4.0 mg/L, it was chosen as the high level for the main study; 0.2 and 0.8 mg/L were chosen to give an approximate 5-fold spacing factor between levels. A 0.4 mg/L level was also used.
- Rationale for animal assignment (if not random): Stratified-by-weight randomisation, to obtain approximately mean bodyweights.
- Post-exposure recovery period in satellite groups: 28 Days

Examinations

Observations and examinations performed and frequency:

CAGE SIDE OBSERVATIONS: Yes
- Time schedule: Twice per day on exposure days (before and after exposure), and once per day on non-exposure days.

DETAILED CLINICAL OBSERVATIONS: Yes / No / No data
- Time schedule:

BODY WEIGHT: Yes
- Time schedule for examinations: Animals were weighed before exposure on days 1, 8, 15, 22, 29, 36, 43, 50, 57, 64, 71, 78, 85, 91, 92, 99, 106, 113, 119, and 120.

FOOD CONSUMPTION:
- Food consumption for each animal determined and mean daily diet consumption calculated as g food/kg body weight/day: Yes (Mean food consumption was measured on a weekly basis).

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: No

OPHTHALMOSCOPIC EXAMINATION: Yes
- Time schedule for examinations: Performed on the day of animal allocation to groups, and in the final week of the administration period.
- Dose groups that were examined: All

HAEMATOLOGY: Yes
- Time schedule for collection of blood: Day 91 for main group (non-recovery) animals, day 119 for recovery group animals.
- Anaesthetic used for blood collection: Yes (Thiopental sodium)
- Animals fasted: Yes
- How many animals: All
- Parameters checked in table 1 were examined.

CLINICAL CHEMISTRY: Yes
- Time schedule for collection of blood: As above (see Haematology)
- Animals fasted: Yes
- How many animals: All
- Parameters checked in table 2 were examined.

URINALYSIS: No

NEUROBEHAVIOURAL EXAMINATION: No

Sacrifice and pathology:

GROSS PATHOLOGY: Yes (see table 3)
HISTOPATHOLOGY: Yes (see table 4)

Results and discussion

Results of examinations

Clinical signs:

effects observed, treatment-related

Mortality:

mortality observed, treatment-related

Body weight and weight changes:

effects observed, treatment-related

Food consumption and compound intake (if feeding study):

effects observed, treatment-related

Food efficiency:

not examined

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

not examined

Ophthalmological findings:

no effects observed

Haematological findings:

no effects observed

Clinical biochemistry findings:

effects observed, treatment-related

Urinalysis findings:

not examined

Behaviour (functional findings):

not examined

Organ weight findings including organ / body weight ratios:

effects observed, treatment-related

Gross pathological findings:

no effects observed

Histopathological findings: non-neoplastic:

effects observed, treatment-related

Histopathological findings: neoplastic:

not examined

Details on results:

CLINICAL SIGNS AND MORTALITY
No rats died during the exposure or recovery period.
Salivation and nasal discharge were seen in the group exposed to 4.0 mg/L after the daily exposure period; these signs were not seen on the non-dosing days.

BODY WEIGHT AND WEIGHT GAIN
During the administration period, the THE SUBSTANCE 4.0 mg/L group had statistically significant lower body weights compared to the control group from Day 22 in males and from Day 36 in females. Males of the THE SUBSTANCE 4.0 mg/L group also indicated statistically significant lower body weight gains compared to the control group. During the recovery period, there were statistically significant lower body weights in males and females of the THE SUBSTANCE 4.0 mg/L group. However, males of the THE SUBSTANCE 4.0 mg/L group had higher body weight gains compared to the control group, but they did not achieve statistical significance.
Females of the THE SUBSTANCE 4.0 mg/L group had a statistically significant higher body weight gain as compared to the control group on Day 113. Additionally, there were statistically significant higher body weights and body weight gains in males of the THE SUBSTANCE 0.2 mg/L group as compared to the control group. However, since there were no similar differences in the other groups exposed to higher concentrations, this difference was considered to be incidental.

FOOD CONSUMPTION
During the administration period, there were statistically significant lower food consumptions in females of the THE SUBSTANCE 4.0 mg/L group on Days 43, 57, and 64 as compared to the control group. There were no statistically significant differences between the control group and the test substance exposed groups during the recovery period.
Males of the THE SUBSTANCE 0.2 mg/L group sporadically indicated statistically significant higher food consumptions as compared to the control group during the administration period; however, since there were no differences in the groups exposed to higher concentrations, the differences were considered not attributed to the test substance administration. Moreover, statistically significant lower food consumptions compared to the control group were sporadically observed in females of the THE SUBSTANCE 0.2, 0.4, and 0.8mg/L groups; however, since these differences did not show continuity and did not coincide with body weight change, the differences were considered not attributed to the test substance administration.

OPHTHALMOSCOPIC EXAMINATION
In the examination before the start of administration or on the final week of the administration period, there were corneal opacity in males of the control group and were particulate opacity in lens, focal opacity in lens, and persistent hyaloid artery in males and females of each group including the control group. These findings were considered to be spontaneous.

HAEMATOLOGY
Males of the THE SUBSTANCE 0.4 mg/L group indicated statistically higher values of reticulocyte ratio and white blood cell count as compared to the control group, and males of THE SUBSTANCE 0.2 mg/L group also indicated higher white blood cell count at the end of the administration period. However, since there were no dose-related pattern in the incidence or severity, these differences were not considered attributed to the test substance administration.
At the end of the recovery period, males of the THE SUBSTANCE 4.0 mg/L group indicated statistically significant higher eosinophil ratio as compared to the control group. However, since this difference did not occur at the end of the administration period and the difference was slight without variations in white blood cell count, the difference was not considered attributed to the test substance administration.

CLINICAL CHEMISTRY
At the end of the administration period, males of the THE SUBSTANCE 4.0 mg/L group indicated statistically higher values of ALAT (GPT) and potassium as compared to the control group. There were no differences in these parameters at the end of the recovery period. Males of the THE SUBSTANCE 0.2 mg/L group revealed statistically higher potassium as compared to the control group at the end of the administration period; however, since there were no differences in this parameter in the THE SUBSTANCE 0.4 or 0.8 mg/L group, the difference was not considered attributed to the test substance administration. Moreover, males of the THE SUBSTANCE 4.0 mg/L group had statistically significant higher values of ALP and chlorine as well as lower triglyceride at the end of the recovery period; however, since these differences did not occur at the end of the administration period, they were not considered attributed to the test substance administration.

ORGAN WEIGHTS
At the end of the administration period, there were the following statistically significant differences as compared to the control group. In the liver, there were higher absolute and relative weight in males of the THE SUBSTANCE 0.2 and 4.0 mg/L groups and higher relative weight in females of the THE SUBSTANCE 4.0 mg/L group and in males of the THE SUBSTANCE 0.8 mg/L group. In the kidneys, there were higher absolute weight in males of the THE SUBSTANCE 0.2 and 4.0 mg/L groups and higher relative weight in males and females of the THE SUBSTANCE 4.0 mg/L group. Males and females of the THE SUBSTANCE 4.0 mg/L group had a lower absolute brain weight. In the salivary gland, there were lower absolute weight in males of the THE SUBSTANCE 0.4, 0.8, and 4.0 mg/L groups and lower relative weight in males of the THE SUBSTANCE 0.2, 0.4, 0.8, and 4.0 mg/L groups. Females of the THE SUBSTANCE 4.0 mg/L group had higher relative heart weight. At the end of recovery period, there were statistically significant higher relative weight in the heart, liver, and kidney in females of the THE SUBSTANCE 4.0 mg/L group among the above differences. Additionally, females of the THE SUBSTANCE 0.8 mg/L group had statistically significant lower absolute and relative ovary weight at the end of the administration period.
Regarding the higher absolute and body weight-relative liver weight and higher absolute kidney weight in males of the THE SUBSTANCE 0.2 mg/L, since there were no similar differences in the THE SUBSTANCE 4.0 mg/L group or dose-related patterns, the differences were not considered to be toxicologically significant. Moreover, since there were no dose-related patterns in higher absolute and body weight-relative ovary weight in females of the THE SUBSTANCE 0.8 mg/L group, the differences were not considered to be toxicologically significant. In the following differences at the end of the recovery period, the lower absolute adrenal weight in males of the THE SUBSTANCE 4.0 mg/L group as well as the higher absolute and body weight-relative thyroid weight and higher body weight relative values of the salivary glands, spleen, and adrenals in females of the THE SUBSTANCE 4.0 mg/L group, there were no differences in these parameters at the end of the administration period. Therefore, these differences were considered to be changes not related to the test substance administration.

GROSS PATHOLOGY
At the end of the administration period, there was crust of the skin observed in clinical observation in males and distention of the uterus in females. Distention of the uterus was observed in one rat each of the control, THE SUBSTANCE 0.2, 0.4, and 0.8 mg/L groups respectively. Since these findings were spontaneously changes in the rats, it was considered not attributed to the test substance administration.
At the end of the recovery period, there was loss of fur observed in clinical observation in males and females. Moreover, scratch wounds were observed in males. Additionally, there were the following findings: small thymus in one female and partial lobe torsion of the liver in one female of the control group, white patch in the lungs in one female of the THE SUBSTANCE 4.0 mg/L group. Since these findings were spontaneous changes, it was considered not attributed to the test substance administration.

HISTOPATHOLOGY: NON-NEOPLASTIC
In the animals subjected to the necropsy at the end of the administration period, a hyaline droplet in proximal tubular epithelium in the kidneys was observed in three males of the THE SUBSTANCE 4.0 mg/L group. Moreover, simple hyperplasia of mucosal epithelium in the urinary bladder was observed in three males and two females of the THE SUBSTANCE 4.0 mg/L group. These findings were not observed in males or females of the THE SUBSTANCE 0.2, 0.4, and 0.8 mg/L groups, as well as the control group. Some histopathological findings were observed in males and females of each group including the control group. However, since these findings were spontaneous findings with no dose-related pattern in their incidence, it was considered not related to the test substance administration.
In the animals subjected to the necropsy at the end of the recovery period, there were no findings in the kidneys and urinary bladder observed in the THE SUBSTANCE 4.0 mg/L group at the end of the administration period.
Accumulation of foam cells was observed in the lungs that showed white patch in the necropsy. However, since this finding was spontaneous finding and was not observed in the animals subjected to the necropsy at the end of the administration period, it was considered to be an incidental change. Moreover, focal necrosis of the liver was observed at the area showing the partial lobe torsion. There was dilatation of hair follicle on the skin that showed loss of fur and there were no histological findings in the small thymus.

Effect levels

1

Dose descriptor:

NOEL

Effect level:

208 ppm (analytical)

Based on:

test mat.

Remarks:

Value quoted at 1 atmosphere and 20°C; converted from actual value of 0.87mg/L.

Sex:

male

Basis for effect level:

other: see 'Remark'

2

Dose descriptor:

NOEL

Effect level:

201 ppm (analytical)

Based on:

test mat.

Remarks:

Value quoted at 1 atmosphere and 20°C; converted from actual value of 0.84mg/L.

Sex:

female

Basis for effect level:

other: Salivation and nasal discharge, lower body weight and bodyweight gain, higher liver and kidney weight, simple hyperplasia in mucosal epithelium of the urinary bladder in female rats treated with 4.67 mg/L

Target system / organ toxicity

Critical effects observed:

not specified

Applicant's summary and conclusion

Conclusions:

Repeated exposure of the substance vapour for 13 consecutive weeks by whole-body inhalation exposure demonstrated toxicological effects in the targeted concentration of 4.0 mg/L. Consequently, the no observed effect level of the substance was concluded to be 208 ppm (20°C, 1 atm, converted from actual value of 0.87 mg/L) for males and 201 ppm (20°C, 1 atm, converted from actual value of 0.84 mg/L) for females under the condition of this study. There was reversibility in all of the adverse effects during the 28 days of the recovery period.