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Repeated dose toxicity: inhalation

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Administrative data

Endpoint:
sub-chronic toxicity: inhalation
Type of information:
migrated information: read-across from supporting substance (structural analogue or surrogate)
Adequacy of study:
weight of evidence
Study period:
not reported
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: see 'Remark'
Remarks:
Data obtained from peer-reviewed publication. Read-across justification: The substance is hydrolytically unstable. When it comes in contact with water or moisture complete hydrolysis will take place with no significant reaction products other than alcohol and hydrated titanium dioxide. This rapid hydrolysis (hydrolysis half-life < 3 minutes to < 2 hours) is the driving force for the toxicokinetics of target substance. Because of the rapid hydrolysis, the influence of the mode of administration through inhalation, dermal and oral is related to the hazardous degradation product (alcohol) released from the target substance. The identification of degradation products from the hydrolysis study conducted for the target substance verifies that there are no impurities in the alcohol released from the target substance, which might change the hazardous properties of the target substance compared to the properties of the pure alcohol. As there is a mechanistic reasoning to the read-across, the unnecessary animal testing is avoided by using the read-across data from the degradation product (relevant alcohol) to evaluate irritation, sensitization and the short term and long-term toxicological effects and mutagenicity of the target substance.

Data source

Reference
Reference Type:
publication
Title:
Unnamed
Year:
1994

Materials and methods

Test guideline
Qualifier:
equivalent or similar to
Guideline:
OECD Guideline 413 (Subchronic Inhalation Toxicity: 90-Day Study)
Deviations:
no
GLP compliance:
yes
Remarks:
According to the published article the study is conducted in a similar way than OECD 413 guideline study
Limit test:
no

Test material

Reference
Name:
Unnamed
Type:
Constituent
Details on test material:
- Name of test material (as cited in study report): Isopropanol, isopropyl alcohol
- Physical state: liquid
- Analytical purity: 99,9%

Test animals

Species:
other: rat and mouse
Strain:
other: Fisher 344 rats and CDR-1 mice
Sex:
male/female
Details on test animals and environmental conditions:
TEST ANIMALS
- Source: Fischer 344 rats from Harlan Sprague-Dawley, Inc. (Indianapolis, IN); CD®-1 mice from Charles River Breeding Laboratories, Inc. (Portage, MI).
- Age at study initiation: rats: 8-12 weeks; mice: 8-10 weeks
- Weight at study initiation: male rats: 140-165 g; female rats: 112-130 g; male mice: 25-37 g; female mice: 19-26 g
- Fasting period before study: not reported
- Housing: individually in stainless steel, wire-mesh cages (15 cm x 22 cm x 18 cm for rats; 22.5 cm x 9.5 cm x 12.5 cm for mice); during exposure, animals were individually housed, separated by sex and exposure group, in stainless steel, wire-mesh cages (14.5 cm x 9.5 cm x 17.5 cm or 17.5 cm x 12 cm x 18 cm for rats, and 7.5 cm x 9.5 cm x 17.5 cm for mice).
- Diet (e.g. ad libitum): powdered food (Certified Rodent Chow 5002, Ralston Purina Co., St. Louis, MO) ad libitum
- Water (e.g. ad libitum): water (Municipal Authority of Westmoreland County, Greensburg, PA) ad libitum
- Acclimation period: animals were acclimated to the exposure chambers (air-only exposure) on 2 days prior to the initiation of the exposure regimen


ENVIRONMENTAL CONDITIONS
- Temperature (°C): 22-24 °C
- Humidity (%): 52-56 %
- Air changes (per hr): 13.5 per hr (in inhalation chamber)
- Photoperiod (hrs dark / hrs light): 12 hrs dark/12 hrs light

Administration / exposure

Route of administration:
inhalation: vapour
Type of inhalation exposure:
whole body
Vehicle:
other: unchanged (no vehicle)
Details on inhalation exposure:
All animals assigned to each exposure group were placed in individual cages and exposed together in one 1330- liter stanless-steel and glass chamber operating at an airflow 300 liters/minute. Among the groups, the daily mean chamber temperature and relative humidity, which were recorded at least 12 times during each exposure ranged from 22 to 24 degrees C and 52 to 56%, respectively..

Target isopropanol vapor concentrations of 0 (control), 100, 500, 1500, and 5000 ppm were selected for this study. The rats (55 days of age) and mice (56 days of age) were exposed for 6 hours per day, 5 days per week for 13 weeks. During the 14th week, male and female rats (excluding those animals designated for neuroanatomic pathology evaluation) received 2 and 3 consecutive days of exposure, respectively. The 10 female rats of the 500, 1500, and 5000 ppm group designated for neuroanatomic pathology evaluation were exposed for 1 day during the 14th week; the male rats of the 500, 1500, and 5000 ppm group designated for neuroanatomic pathology evaluation were not exposed during the 14th week. Male and female mice received 4 and 5 consecutive days of exposure during the 14th week, respectively. The 6-hour exposure interval was defined as the time when the vapor generation system was turned on and subsequently turned off. Control (air-only exposure) animals were handled in an identical manner as the isopropanol-exposed animals.

Liquid isopropanol was generated by metering the liquid test substance from a piston pump (Fluid Metering, Inc., Oyster Bay, NY) into heated, spiral-grooved glass evaporator with a countercurrent airstream.
Analytical verification of doses or concentrations:
yes
Details on analytical verification of doses or concentrations:
Chamber concentrations of isopropanol vapor were analyzed at 30-min intervals using Perkin Elmer 8500 gas chromatograph (GC) equipped with a flame ionization detector. The GC column was a 6ft x 1/8in. stainless-steel column packed with 10% SP2100 on 80/100 mesh Supercoport (Supeco, Bellefonte, PA) maintained at 90 degrees C. In jections of gas standrds were used to calibrate the GC. Chamber atmosphere samples were automatically injected into the GC using environmental sampling system (John Booker & Company, Austin,TX)
Duration of treatment / exposure:
13 weeks
Frequency of treatment:
6 hours per day, 5 days per week
Doses / concentrationsopen allclose all
Remarks:
Doses / Concentrations:
100 ppm
Basis:
nominal conc.
Remarks:
Doses / Concentrations:
500 ppm
Basis:
nominal conc.
Remarks:
Doses / Concentrations:
1500 ppm
Basis:
nominal conc.
Remarks:
Doses / Concentrations:
5000 ppm
Basis:
nominal conc.
No. of animals per sex per dose:
All exposure groups (except for the 100 ppm group) consisted of 25 rats/sex. Ten rats per sex were assigned to the 100 ppm group. Ten mice per sex were assigned to each exposure group.
Control animals:
yes, sham-exposed
Details on study design:
- Dose selection rationale: not reported
- Rationale for animal assignment (if not random): animals were assigned to the 4 exposure groups and one air-exposed control group using a computer-based randomization program
- Rationale for selecting satellite groups: not applicable
- Post-exposure recovery period in satellite groups: not applicable
- Section schedule rationale (if not random): not reported
Positive control:
not applicable

Examinations

Observations and examinations performed and frequency:
CAGE SIDE OBSERVATIONS: Yes
-During exposures, observations were recorded on a group basis. Preceding and following each exposure, animals were examined individually, and observations were recorded for each animal exhibiting overt clinical signs.

DETAILED CLINICAL OBSERVATIONS: No data

BODY WEIGHT: Yes
- All rats and mice were weighed on Week 0 (prior to the start of exposures). Animals were weighed weekly during the study, at neurobehavioral evaluations, and immediately preceding sacrifice.

FOOD CONSUMPTION: Yes
- Food consumption was determined weekly (by weight) for each animal

WATER CONSUMPTION: Yes
- Water consumption was determined weekly (by weight) for each animal

OPHTHALMOSCOPIC EXAMINATION: Yes
- Prior to the first exposure and during Week 12 all rats and mice

HAEMATOLOGY: Yes
- During the 6th week of the study in 10 rats/sex/group. At sacrifice in 10 rats/sex/group and 10 mice/sex/group.

CLINICAL CHEMISTRY: Yes
- At sacrifice 10 rats/sex/group and 10 mice/sex/group

NEUROBEHAVIOURAL EXAMINATION: Yes (rats only)
- 10/15 rats were evaluated with the functional observational battery (FOB) prior to the first exposure and on the weekend following Weeks 1, 2, 4, 9, and 13. Motor activity evaluations were conducted on all 15 rats per sex selected from the 0, 500, 1500, and 5000 ppm groups prior to the first exposure and on the weekend following Weeks 4, 9, and 13.

Other examinations:
Organ Weights: The brain, liver, lungs, kidneys, adrenals, testes (males), and ovaries (females) from all surviving animals (except animals designated for neuroanatomic pathology evaluation) were weighed at sacrifice. For rats designated for neuroanatomic pathology evaluation, the brain was weighed and measured (length and width).

Results and discussion

Results of examinations

Clinical signs:
effects observed, treatment-related
Description (incidence and severity):
No exposure-related mortality was observed. Irritating effects included swollen periocular tissue at concentration 5000ppm (female rats) and perinasal encrustation at concentration 500, 1500, 5000ppm (male rats)
Mortality:
mortality observed, treatment-related
Description (incidence):
No exposure-related mortality was observed. Irritating effects included swollen periocular tissue at concentration 5000ppm (female rats) and perinasal encrustation at concentration 500, 1500, 5000ppm (male rats)
Body weight and weight changes:
effects observed, treatment-related
Description (incidence and severity):
transient change in body weight and body weight gain during the first week in male and female rats of the 5000ppm group and female rats of the 1500ppm group
Food consumption and compound intake (if feeding study):
effects observed, treatment-related
Description (incidence and severity):
decreased during the first week
Food efficiency:
not examined
Water consumption and compound intake (if drinking water study):
effects observed, treatment-related
Description (incidence and severity):
incresed water consumption in both male and female rats rats of the 1500 and 5000 ppm groups.
Ophthalmological findings:
no effects observed
Description (incidence and severity):
no notable eye lesions
Haematological findings:
effects observed, treatment-related
Description (incidence and severity):
Certain hematologic effects seen in male and female rats
Clinical biochemistry findings:
effects observed, treatment-related
Description (incidence and severity):
Exposure-related changes in serum clinical chemistry parameters was observed in female mice at 5000ppm concentration
Urinalysis findings:
not examined
Behaviour (functional findings):
effects observed, treatment-related
Description (incidence and severity):
An increase in motor activity was observed in female rats of the 5000 ppm group
Organ weight findings including organ / body weight ratios:
effects observed, treatment-related
Description (incidence and severity):
An increased liver weight was observed for both sexes of rats and female mice of the 5000 ppm group
Gross pathological findings:
no effects observed
Description (incidence and severity):
No gross lesions were observed
Histopathological findings: non-neoplastic:
effects observed, treatment-related
Description (incidence and severity):
the presence of increased numbers and sizes of hyaline droplets within the kidneys
Histopathological findings: neoplastic:
not specified
Details on results:
CLINICAL SIGNS AND MORTALITY
No exposure-related mortality was observed in rats or mice of any exposure group during the study. During exposures, ataxia, narcosis, hypoactivity, and a lack of a startle reflex were observed in some rats and mice of the 5000 ppm group; narcosis was not observed in rats after Week 2 of the study. During exposures to 1500 ppm, narcosis, ataxia, and hypoactivity were observed in some mice, while only hypoactivity was observed in rats. No clinical signs were noted during exposures for either rats or mice of the 100 and 500 ppm groups. Clinical signs observed following exposures included a markedly increased incidence of swollen periocular tissue in rats of the 5000 ppm group (females only) and an increased incidence of perinasal encrustation in male rats of the 500, 1500, and 5000 ppm groups. Additionally, ataxia and/or hypoactivity were observed in one male rat, three female mice, and one male mouse of the 5000 ppm group immediately following exposure. No exposure-related clinical signs were observed following exposures in male or female rats of the 100 ppm group; no exposure-related clinical signs were observed following exposures for male or female mice of the 100, 500, and 1500 ppm groups.

BODY WEIGHT AND WEIGHT GAIN
Absolute body weight and/or body weight gains for the male and female rats of the 5000 ppm group were statistically significantly lower at the end of Week 1. Decreased body weight and body weight gain were also observed in the female rats of the 1500 ppm group at the end of Week 1.

Decreased body weight and/or body weight gain observed in rats during Week 1 were not present during the second week of the study. In contrast to the initial decrease, absolute body weight and body weight gains were increased (usually statistically significantly) beginning at approximately Week 5 in both male and female rats of the 1500 and 5000 ppm groups. At the end of Week 13, the percent increases in body weight gain were 12% and 16% for the male and female rats of the 5000 ppm group, respectively, and 7% and 8% for the male and female rats of the 1500 ppm group, respectively.

Statistically significantly increased body weight and body weight gain (starting at approximately Week 3) were also observed in female mice of the 5000 ppm group. The percent increases in body weight and body weight gain at the end of the study were 13% and 71%, respectively. There were no exposure-related effects on body weight or body weight gain of male mice during the study.


FOOD CONSUMPTION
A statistically significant decrease in food consumption was observed in female rats of the 5000 ppm group at the end of Week 1. In contrast to the initial decrease, statistically significant increases in food consumption were observed for both sexes of rats of the 5000 ppm group beginning at Week 4 or 5. Percentage increases in fod consumption were 5 and 13 % at the end of Week 13 for the male and female rats of the 5000ppm group, respectively. There were no exposure-related effects on food consumption in male or female mice of any exposure group.


WATER CONSUMPTION
Increased water consumption was observed (beginning at approximately Week 2) in both male and female rats of the 1500 and 5000 ppm groups. Increased water consumption was also observed for male mice of the 1500 and 5000 ppm group during Weeks 1 and 2. Water consumption was increased for female mice of the 5000 ppm group throughout the study.

OPHTHALMOSCOPIC EXAMINATION
There were no notable eye lesions for either rats or mice

HAEMATOLOGY
Decreased total erythrocytes, hemoglobin, hematocrit, and platelet counts were observed at Week 6 in both sexes of rats.of the 5000 ppm group. In addition, increased MCV and MCH were noted at this time point for male rats. Lymphocytes were also increased at Week 6 for females of the 5000 ppm group. At Week 6 in the 1500 ppm group, decreased platelet counts were observed for male rats, and decreased total erythrocytes were noted for female rats.
Certain hematologic effects seen in male and female rats of the 5000 ppm group at Week 6, such as decreased total erythrocytes, hemoglobin, and hematocrit, were no longer present at Week 14. However, at Week 14, MCV and MCH were still increased in male rats of the 5000 ppm group. In addition, increased MCV was also observed for female rats of the 5000 ppm group. In contrast to the decrease observed at Week 6, platelet counts were increased in the 1500 and 5000 ppm groups of male rats.

CLINICAL CHEMISTRY
There were no exposure-related changes in serum clinical chemistry parameters for male or female rats at Week 14. Increased total protein, albumin, globulin, total bilirubin, direct bilirubin, and inorganic phosphorus along with decreased serum chloride were observed for female mice of the 5000 pppm group at Week 14. There were no exposure-related changes in serum clinical chemistry parameters for male mice.

NEUROBEHAVIOUR
Exposure of rats to isopropanol did not result in changes in the functional observational battery performed following Weeks 1, 2, 4, 9, and 13 of exposure. An increase in motor activity was observed in female rats of the 5000 ppm group following Weeks 9 and 13. The percent increase in motor activity for female rats was 57% and 26% for Weeks 9 and 13, respectively. No motor activity were noted at any time point for male rats.

ORGAN WEIGHTS
The only organ in which possible exposure-related effects occurred was the liver. An increased relative liver weight, as a percentage of body weight, was observed for both sexes of rats and female mice of the 5000 ppm group.

GROSS PATHOLOGY
No gross lesions were observed in any animal that could be attributable to isopropanol vapor exposures.

HISTOPATHOLOGY: NON-NEOPLASTIC
Upon histologic examination, the only exposure-related changes observed were the presence of increased numbers and sizes of hyaline droplets within the kidneys of male rats. These differences were not clearly concentration-related, although this microscopic change was most pronounced in the high concentration group. Hyaline droplets were not observed within the kidneys of female rats.

Effect levels

Dose descriptor:
NOAEC
Effect level:
5 000 ppm
Basis for effect level:
other: see 'Remark'

Target system / organ toxicity

Critical effects observed:
not specified

Any other information on results incl. tables

Read-across justifications and data matrices are presented in IUCLID section 13.

Applicant's summary and conclusion

Conclusions:
A repeated dose toxicity of propan-2-ol was evaluated in a subchronic study, where rats and mice were exposed to propan-2-ol vapor for 13-weeks. Repeated exposure to propan-2-ol produced toxic effects only at 5000 ppm (12 300mg/m3) and a kidney change of unknown biological significance.
Executive summary:

Target isopropanol concentrations of 0 (control), 100, 500, 1500 and 5000 ppm were selected for this study. The rats and mice were exposed for 6 hours per day, 5 days per week for 13 weeks.During the 14th week, male and female rats (excluding those animals designated for neuroanatomic pathology evaluation) received 2 and 3 consecutive days of exposure, respectively. The 10 female rats of the 500, 1500, and 5000 ppm group designated for neuroanatomic pathology evaluation were exposed for 1 day during the 14th week; the male rats of the 500, 1500, and 5000 ppm group designated for neuroanatomic pathology evaluation were not exposed during the 14th week. Male and female mice received 4 and 5 consecutive days of exposure during the 14th week, respectively.

The results of this study show that exposure to propan-2 -ol vapor at the concentrations tested produced few adverse effects and no mortality. Clinical signs of toxicity on the central nervous system (including ataxia, narcosis, lack of a startle reflex, and/or hypoactivity) are acute effects and not relevant for limit value determination for repeated dose systemic effects. Decreases in absolute body weight and body weight gain, and changes in hematology parameters in animals exposed to 1500 and 5000 ppm of propan-2 -ol, increased relative liver weight in male and female rats exposed to 5000 ppm, as well as increased motor activity for female rats in the 5000 ppm group have been observed.

The study is considered reliable with restrictions, though the original study is performed according to OECD 413 guideline, the publication do not present all details on study design, used methods and obtained results.