Propan-2-ol

Carcinogenicity

Description of key information

Two  inhalation, carcinogenicity studies conducted according to GLP and to OECD test guideline 451 reported carcinogenicity NOECs for isopropyl alcohol (IPA) of 5000 ppm (Burleigh-Flayer and Wagner, 1993; Burleigh-Flayer and Benson, 1994).

Key value for chemical safety assessment

Carcinogenicity: via oral route

Endpoint conclusion

Endpoint conclusion:

no study available

Carcinogenicity: via inhalation route

Link to relevant study records

Reference

Reference 1

Endpoint:

carcinogenicity: inhalation

Type of information:

experimental study

Adequacy of study:

key study

Study period:

1994

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Remarks:

Well documented, according to accepted guidelines

Qualifier:

according to guideline

Guideline:

OECD Guideline 451 (Carcinogenicity Studies)

Deviations:

yes

Remarks:

- Not monitoring food consumption

GLP compliance:

yes

Species:

rat

Strain:

Fischer 344

Sex:

male/female

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Source: Harlan Sprague Dawley Inc. Indianapolis, IN
- Age at study initiation: 28-30 days old
- Weight at study initiation: 121.2-165 g (males) and 93.6 - 124.3 g (females) on the first day of exposure
- Fasting period before study: None
- Housing: 2 per cage in stainless steel, wire mesh cages
- Diet (e.g. ad libitum): Pelleted, certified AGWAY PROLAB animal diet rat 3000 ad libitum
- Water (e.g. ad libitum): tap water ad libitum
- Acclimation period: 3 weeks


ENVIRONMENTAL CONDITIONS
- Temperature : 17 - 26 °C
- Humidity (%): 40-70%
- Air changes (per hr): Not reported
- Photoperiod (hrs dark / hrs light): 12-12

Route of administration:

inhalation: vapour

Type of inhalation exposure (if applicable):

whole body

Vehicle:

unchanged (no vehicle)

Details on exposure:

GENERATION OF TEST ATMOSPHERE / CHAMBER DESCRIPTION
- Exposure apparatus: Inhalation chamber (Wahmann Manufacting company, Timonium, MD)
- System of generating particulates/aerosols: liquid isopropanol was metered from a container by piston pump
- Temperature in air chamber: 22 ± 4 degrees
- Air flow rate: 1000 l/min for first month and 900 l/min thereafter
- Air change rate: 14 air changes/hr for first month and 12.5 air changes/hr thereafter
- Method of particle size determination: not reported
- Treatment of exhaust air: not reported


TEST ATMOSPHERE
- Brief description of analytical method used: liquid isopropanol was metered from a container by piston pump into a heated glass evaporator and the temperature of the evaporators was maintained at the lowest level to sufficiently vaporize the test substance.
- Samples taken from breathing zone: yes

Analytical verification of doses or concentrations:

yes

Details on analytical verification of doses or concentrations:

Each exposure chamber was analyzed for isopropanol twice each hour by flame ionization gas chromatography.

Duration of treatment / exposure:

At least 104 weeks

Frequency of treatment:

6 hours/day, 5 days/week

Remarks:

Doses / Concentrations:
0, 500, 2500, or 5000 ppm
Basis:
nominal conc.

No. of animals per sex per dose:

65 sex/dose for the core group and 10 sex/dose for the interm sacrifice

Control animals:

yes, sham-exposed

Details on study design:

- Rationale for animal assignment (if not random): animals were assigned to 3 exposure groups and a control group using a stratified randomization procedure based on body weight
- Rationale for selecting satellite groups: 10 sex/group were sacrified in the middle of the study

Positive control:

None

Observations and examinations performed and frequency:

CAGE SIDE OBSERVATIONS: Yes
- Time schedule: twice a day

DETAILED CLINICAL OBSERVATIONS: Yes
- Time schedule: weekly

BODY WEIGHT: Yes
- Time schedule for examinations: weekly for the first 14 weeks and then every other week after

FOOD CONSUMPTION:
- Food consumption for each animal determined and mean daily diet consumption calculated as g food/kg body weight/day: No data

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 data

WATER CONSUMPTION: No data

OPHTHALMOSCOPIC EXAMINATION: Yes
- Time schedule for examinations: prior to experiment, and during weeks 71, 80, 104, and 107
- Dose groups that were examined: all rats

HAEMATOLOGY: Yes
- Time schedule for collection of blood: 13 months, 19 months, and 25 months
- Anaesthetic used for blood collection: Yes (identity) methoxyflurane
- Animals fasted: No
- How many animals: 10 sex/dose level

CLINICAL CHEMISTRY: Yes
- Time schedule for collection of blood: week 57
- Animals fasted: No
- How many animals: 10 sex/dose group

URINALYSIS: Yes
- Time schedule for collection of urine: week 57, 59, 74, and 104
- Metabolism cages used for collection of urine: No
- Animals fasted: No

NEUROBEHAVIOURAL EXAMINATION: No

Sacrifice and pathology:

GROSS PATHOLOGY: Yes
HISTOPATHOLOGY: Yes

Other examinations:

None

Statistics:

The data for the 3 treatment groups and the control group were compared with Levene's test for equality of variances, analysis of variance (ANOVA), and t-tests. The nonparmetric data were statistically evaluated with the Kruskal-Wallis test followed by the Mann-Whitney U-test. Mortality was analysed by life-table analyses. Incidence data were compared using Fishers exact test.

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):

not examined

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:

no effects observed

Urinalysis findings:

effects observed, treatment-related

Behaviour (functional findings):

no effects observed

Organ weight findings including organ / body weight ratios:

effects observed, treatment-related

Gross pathological findings:

effects observed, treatment-related

Histopathological findings: non-neoplastic:

effects observed, treatment-related

Histopathological findings: neoplastic:

effects observed, treatment-related

Details on results:

CLINICAL SIGNS AND MORTALITY
- Mortality rates for males in the 0, 500, 2500, and 5000 ppm groups were 82, 83, 91, and 100%, respectively. For females, 54, 48, 55, and 69%. No significant differences were noted for male rats from 500 or 2500 groups or any female rats.
-In males and females exposed to 5000 ppm; hypoactivity, lack of a startle reflex, and narcosis were identified. In males and females exposed to 2500 ppm; hypoactivity, and a lack of a startle reflex were observed. No effects in 500 ppm group. During non-exposure periods in males 5000 ppm group emaciation and dehydration was observed. In males and females in 5000 ppm there was greater numbers of rats with urine stains and swollen periocular tissue (females only). Females in the 2500 ppm group also had increased incidence of urine stains.

BODY WEIGHT AND WEIGHT GAIN
-Decreased body weights were observed for male rats from the 5000 ppm group in the first and second weeks of exposure, and then increased and at the end of week 6 body weights were increased significantly over the control group. Increased body weights were also noted for male rats from the 2500 ppm group.
-Decreased body weights were observed for female rats from the 5000 ppm group in the first and second weeks of exposure, and then increased and at the end of week 5 body weights were increased significantly over the control group. Increased body weights were also noted for female rats from the 500 ppm group. At week 72, all female body weights were significantly increased when compared to the control group.

URINALYSIS
-In males in the 5000 ppm group, in weeks 57, 59, 74, and 104 decrease in osmolality and increase in total protein and total volume were reported.
-In females rats in the 5000 ppm group, a decrease in osmolality and an increase in total volume was reported. At week 74, total glucose excreted in the urine was increased for females in the 5000 ppm group.


ORGAN WEIGHTS
- At the interim sacrifice, absolute and relative kidney weights were increased for male rats in the 5000 ppm group. Relative liver weights were increased for male rats in the 2500 ppm group. Concentration-related increases in absolute and relative testes weight was reported for male rats in 5000 ppm group. In females, increases in absolute and relative lung weight for rats in the 5000 ppm was reported.
-At the terminal sacrifice, increase in relative liver weight was noted for male rats in 2500 ppm group. In females, an increase in absolute and relative liver and kidney weights were noted for the 5000 ppm group.


GROSS PATHOLOGY
- At the interim sacrifice, an increase in granular kidneys in male rats from the 2500 and 5000 ppm groups were noted
- At the terminal sacrifice, an increase in granular kidneys in male rats from the 2500 ppm group was noted. Increased frequencies of gross lesions for male rats that died included increase incidence of thickened stomachs, granular kidneys, and color change of the kidneys for animals in 2500 and 5000 ppm groups.
- For females that died before the end of the study, an increased incidence of thickened stomachs was noted for animals from the 5000 ppm group and granular kidneys were noted for animals from the 2500 and 5000 ppm groups.


HISTOPATHOLOGY: NON-NEOPLASTIC
- At the interim sacrifice, male rats from the 5000 ppm group had an increased frequency of testicular seminiferous tubule atrophy.
-Increased frequencies of kidney lesions were observed in male rats in the 2500 and 5000 dose groups that died during the study. Increased in the frequency of mineralization in the heart, aorta, vasculature, stomach, larynx, trachea, lungs, kidney, cornea, and testes was noted for male rats in the 2500 and 5000 ppm dose groups that died during the study. Additionally, basophilic cell foci in the liver, splenic hemosiderosis, rhinitis, and squamous metaplasisa of the respiratory epithelium in the nasal cavity were reported for male rats in the 5000 ppm group that died during the study.
-Increased severity of glomerulosclerosis was observered in female rats in the 5000 ppm group. Renal disease was also increased in female rats in the 5000 ppm group.
- For female rats that died during the study, increased frequencies of mineralization in the heart, aorta, vasculature, stomach, larynx, trachea, lungs and kidney. Increase in myocardial degeneration, atrial thrombosis, splenic hemosiderosis, ocular keratitis, inflammatory and metaplastic changes in the nasal cavity, squamous metaplasia of the respiratory epithelium and glandular ectasia in the gastric mucosa was also evident in females in the 5000 ppm group that died during the study.


HISTOPATHOLOGY: NEOPLASTIC (if applicable)
-Dose-related increase in interstitial cell adenomas of the testis in male rats at interim sacrifice, at the terminal sacrifice, and in male rats that died during the study.

Dose descriptor:

NOEL

Remarks:

Effect type: carcinogenicity

Effect level:

5 000 ppm (nominal)

Sex:

male/female

The study authors noted that the increased incidence of testicular tumors appeared to be reflective of lower incidence in the control group. The study authors stated that testicular adenomas are a common finding in aged male rats and that historical incidence of this finding has been reported to be high as 88% in NTP inhalation studies, which is much higher compared to an incidence of 64.9% reported for control animals in the study. Therefore, the testicular adenomas were considered possibly spurious by the study authors. 

Reference 2

Endpoint:

carcinogenicity: inhalation

Type of information:

experimental study

Adequacy of study:

key study

Study period:

1993

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

guideline study without detailed documentation

Qualifier:

equivalent or similar to guideline

Guideline:

OECD Guideline 451 (Carcinogenicity Studies)

Deviations:

yes

Remarks:

- opthalmology examinations, food and water consumption, and clinical chemistry not reported

GLP compliance:

yes

Species:

mouse

Strain:

CD-1

Sex:

male/female

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Source: Charles River Laboratories, Portage, MI
- Age at study initiation: 48 days
- Housing: 2 per cage in stainless steel wire mesh cages
- Diet (e.g. ad libitum): Pelleted, certified AGWAY PROLAB Animal Diet Mouse 3000, ad libitum
- Water (e.g. ad libitum): tap water, ad libitum
- Acclimation period: 3 weeks


ENVIRONMENTAL CONDITIONS
- Temperature (°C): 17.7-26.1
- Humidity (%): 40-70
- Air changes (per hr): 14
- Photoperiod (hrs dark / hrs light): 12/12


IN-LIFE DATES: From: February 18, 1991 To: September 2, 1992

Route of administration:

inhalation: vapour

Type of inhalation exposure (if applicable):

whole body

Vehicle:

unchanged (no vehicle)

Details on exposure:

GENERATION OF TEST ATMOSPHERE / CHAMBER DESCRIPTION
- Exposure apparatus: Inhalation chamber
- Method of holding animals in test chamber: cage in chamber
- Temperature, humidity, pressure in air chamber: 22 ± 4°C
- Air flow rate: 1000 L/min
- Air change rate: 14 air changes/hour

TEST ATMOSPHERE
- Brief description of analytical method used: analyzed approximately twice each hour during the 6-hour exposure period by flame ionization gas chromotography

Analytical verification of doses or concentrations:

yes

Details on analytical verification of doses or concentrations:

Analyzed approximately twice each hour during the 6-hour exposure period by flame ionization gas chromotography.

Duration of treatment / exposure:

The exposures began on February 18, 1991 (Study Day 1). Animals assigned to the core group were exposed for at least 78 weeks. The animals assigned to the interim sacrifice group and the animals assigned to the recovery group were exposed for at least 54 weeks.

Frequency of treatment:

Animals assigned to the core group were exposed for 6 hours/day for 5 consecutive days/week for at least 78 weeks. The animals assigned to the interim sacrifice group and the animals assigned to the recovery group were exposed for 6 hours/day for 5 consecutive days/week for at least 54 weeks. Animals were not exposed during designated BRRC holidays. (Use of non-standard dosing regime was not justified in the study report).

Remarks:

Doses / Concentrations:
0, 500, 2500, 5000 ppm
Basis:
nominal conc.

No. of animals per sex per dose:

Core group: 55/sex/dose
Interim Sacrifice group: 10/sex/dose
Recovery group: 10/sex/dose

Control animals:

yes, concurrent no treatment

Details on study design:

- Dose selection rationale: based on 9-day preliminary study
- Rationale for animal assignment (if not random): random

Observations and examinations performed and frequency:

CAGE SIDE OBSERVATIONS: Yes
- Time schedule: twice a day before and after each exposure


DETAILED CLINICAL OBSERVATIONS: Yes
- Time schedule: weekly for the first 14 weeks and every other week thereafter


BODY WEIGHT: Yes
- Time schedule for examinations: weekly for the first 14 weeks and every other week thereafter


OPHTHALMOSCOPIC EXAMINATION: No


HAEMATOLOGY: Yes
- Time schedule for collection of blood: at 12 months and 18 months
- Anaesthetic used for blood collection: Yes : slightly anesthetized wtih methoxyflurane
- Animals fasted: No
- How many animals: all surviving animals

Sacrifice and pathology:

GROSS PATHOLOGY: Yes
HISTOPATHOLOGY: Yes

Statistics:

The data for quantitative continuous variables were intercompared for the 3 exposure groups and the control group by use of Levene's test for equality of variances, analysis of variance (ANOVA), and t-tests. The t-tests were used when the F value from the ANOVA was significant. When Levene's test indicated similar variances, and the ANOVA was significant, a pooled t-test was used for pairwise comparisons. When Levene's test indicated heterogeneous variances, all groups were compared by an ANOVA for unequal variances followed, when necessary, by a separate variance t-test for pairwise comparisons.

Clinical signs:

no effects observed

Mortality:

no mortality observed

Body weight and weight changes:

effects observed, treatment-related

Food consumption and compound intake (if feeding study):

not examined

Food efficiency:

not examined

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

not examined

Ophthalmological findings:

not examined

Haematological findings:

no effects observed

Clinical biochemistry findings:

not examined

Behaviour (functional findings):

not examined

Organ weight findings including organ / body weight ratios:

effects observed, treatment-related

Gross pathological findings:

effects observed, treatment-related

Histopathological findings: non-neoplastic:

no effects observed

Histopathological findings: neoplastic:

no effects observed

Details on results:

CLINICAL SIGNS AND MORTALITY
Mortality rates for males in the 0, 500, 2500, and 5000 ppm groups were 35, 40, 47, and 44%, respectively. The corresponding values for females were 24, 35, 22, and 33%, respectively. No differences in mean survival time were noted for any of the isopropanol exposure groups. Clinical signs noted in some male and female mice during exposures to 500 ppm included hypoactivity, lack of a startle reflex, ataxia, prostration, and narcosis. Hypoactivity, lack of startle reflex, and narcosis were also noted for some male ane female animals during exposure to 2500ppm. No clinical signs were noted for male or female animals during exposure to 500 ppm.

BODY WEIGHT AND WEIGHT GAIN
Concentration-related increases in body weight and weight gain were observed for male mice at most time ponts throughout the study, however, statistical significance was typically achieved only for the 2500 and 5000 ppm groups beginning at study week 6 and 3, respectively.


HAEMATOLOGY
No exposure-related changes in hematologic parameters were observed for male or female mice from any of the isopropanol exposed groups that were examined at week 56 or 57, or at the terminal sacrifice.


ORGAN WEIGHTS
A concentration -related increase in absolute and relative liver weight was noted for female mice at the terminal sacrifice, however, statistical significance was only achieved for animals from the 5000 ppm group.

GROSS PATHOLOGY
At terminal sacrifice, an increased frequency of seminal vesicle enlargement was noted at necropsy for male mice from the 5000 ppm group. In addition, the frequencey of this finding was increased for male mice from the 2500 and 5000 ppm groups which were found dead or sacrificed morbund. There were not exposure-related gross lesions noted for female animals at necropsy.

HISTOPATHOLOGY: NON-NEOPLASTIC
Upon microscopic evaluation, there were no nonneoplastice or neoplastic lesions observed that were believed to be related to the isopropanol exposures for male and female mice which were sacrificed at week 55.

HISTOPATHOLOGY: NEOPLASTIC (if applicable)
Upon microscopic evaluation, there were no nonneoplastice or neoplastic lesions observed that were believed to be related to the isopropanol exposures for male and female mice which were sacrificed at week 55.

Dose descriptor:

NOEL

Remarks:

Effect type: carcinogenicity

Effect level:

5 000 ppm (nominal)

Sex:

male/female

Basis for effect level:

other: see 'Remark'

Refer to Section on Results and discussions.

Endpoint conclusion

Endpoint conclusion:

adverse effect observed

Dose descriptor:

NOAEC

12 290 mg/m³

Justification for classification or non-classification

The substance does not meet the criteria for classification and labelling for carcinogenicity, as set out in Regulation (EC) No. 1272/2008.

Additional information

The carcinogenicity of isopropyl alcohol (IPA) was evaluated in a 2-year carcinogenicity study in rats (Burleigh-Flayer and Benson, 1994). This GLP study was conducted according to OECD test guideline 451. IPA was administered by inhalation at nominal concentrations of 0, 500, 2500, or 5000 ppm to Fischer 344 rats for 2 years, 6 hours/day, 5 days/week (65 rats/sex/group). A subset of 10 animals/sex/group was sacrificed halfway through the study for analysis. All animals underwent complete gross necropsy and microscopic examinations.   There were no differences in survival reported. Observed clinical signs included hypoactivity and lack of a startle reflex, starting at 2500 ppm in both male and female rats. Narcosis was observed in male and female rats at the 5000 ppm dose level. During non-exposure periods, emaciation and dehydration were observed in the high-dose males. Increased number of rats with urine stains (males and females) and swollen periocular tissue (females) were observed in high-dose rats. Female rats in the mid-dose group also had increased incidence of urine stains. Transient decreases in body weight were initially noted in both male and female rats. By week 72, all IPA-treated female body weights were increased compared to controls and body weights for the 2500 ppm and 5000 ppm males were increased compared to controls by week 6.   Decreased urine osmolality and increased urine volume were noted for high-dose male and female rats by week 104. Increased total urine protein also was reported for high-dose males.   At the interim sacrifice, absolute and relative kidney weights were increased for male rats in the 5000 ppm group. These kidney weight changes were not present in males during the terminal sacrifice; however, terminal absolute and relative kidney weights were increased in the 5000 ppm females. Interim and terminal relative liver weights were increased for male rats in the 2500 ppm group. Terminal absolute and relative liver weights were increased for females in the 5000 ppm group. Increases in liver weights were attributed by the study authors to microsomal enzyme induction. Concentration-related increases in interim absolute and relative testes weights were observed, achieving statistical significance in the 5000 ppm group. These changes in testes weights were no longer apparent during the terminal sacrifice. Increase in interim relative and absolute lung weights were reported in high-dose females; however, these changes were not noted at the terminal sacrifice.   Gross pathology observations included an increase in granular kidneys in male rats at 2,500 and 5000 ppm during the interim sacrifice and at 5000 ppm during the terminal sacrifice. Gross findings from preterminal animals included increased incidence of thickened stomachs in the mid-dose males and high-dose males and females, granular kidneys in mid- and high-dose males and females, and color change of the kidneys in mid- and high-dose males.    Histopathology of non-neoplastic lesions reported an increase in frequency of testicular seminiferous tubule atrophy in high-dose males at the interim sacrifice. Findings reported for male premature decedents in the 2500 and 5000 dose groups included kidney lesions, and mineralization of the heart, aorta, vasculature, stomach, larynx, trachea, lungs, kidney, cornea, and testes. Findings of basophilic cell foci in the liver, splenic haemosiderosis, rhinitis, and squamous metaplasia of the respiratory epithelium of the nasal cavity also were reported for high-dose premature decedent males. In premature decedent high-dose females, increased frequencies of mineralization in the heart, aorta, vasculature, stomach, larynx, trachea, lungs, and kidney were noted. Additionally, increases in myocardial degeneration, atrial thrombosis, splenic haemosiderosis, ocular keratitis, inflammatory and metaplastic changes in the nasal cavity, squamous metaplasia of the respiratory epithelium and glandular ectasia in the gastric mucosa also were reported. In surviving female rats, an increased severity of glomerulosclerosis and renal disease was noted at the 5000 ppm concentration level.   Histopathology of neoplastic lesions indicated a dose-dependent increase in interstitial cell adenomas of the testis in male rats at all sampling time points, including premature decedents. The study authors postulated that these changes represented marked hyperplasia and were not representative of growth. Additionally, the increased incidence of testicular tumors appeared to be reflective of lower incidence in the control group. The study authors noted that testicular adenomas are a common finding in aged male rats and that historical incidence of this finding has been reported to be high as 88%, which is much higher compared to an incidence of 64.9% reported for control animals in the study. Therefore, the testicular adenomas were considered possibly spurious by the study authors. There were no increases in neoplastic lesions reported for females.   Given the irrelevance of the neoplastic lesions in this rat study to humans, a carcinogenicity NOEC of 5000 ppm was identified by the study authors.  

Further information on the carcinogenicity of IPA was provided by another key GLP carcinogenicity report; an 18 -month study in CD-1 mice (equivalent to OECD test guideline 451) which used concentration levels of 0, 500, 2500, or 5000 ppm (Burleigh-Flayer and Wagner, 1993). The study authors noted a few microscopic non-neoplastic lesions in IPA exposed animals; however, these findings were minimal in degree and deemed (by the study authors) to be not biologically significant. There were no increased frequencies of neoplastic lesions noted for male or female mice from any test substance exposure group. Clinical signs noted in some male and female mice during exposures to 5000 ppm included hypoactivity, lack of a startle reflex, ataxia, prostration, and narcosis. Hypoactivity, lack of startle reflex, and narcosis were also noted in some male and female animals during exposure to 2500 ppm. No clinical signs were noted for male or female animals during exposure to 500 ppm. A NOEC of 5000 ppm for carcinogenicity was reported.