2-hexyloxyethanol

Repeated dose toxicity: dermal

Administrative data

Endpoint:

short-term repeated dose toxicity: dermal

Type of information:

experimental study

Adequacy of study:

key study

Study period:

1989

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: This study was conducted in accordance with GLP and similar to OECD guideline 410. However, the study duration was only 11 days.

Cross-reference

Cross-reference 1

Reason / purpose for cross-reference:

reference to same study

Cross-reference 2

Reason / purpose for cross-reference:

reference to other study

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

1989

Report date:

1989

Materials and methods

Test guideline

Qualifier:

equivalent or similar to guideline

Guideline:

OECD Guideline 410 (Repeated Dose Dermal Toxicity: 21/28-Day Study)

Principles of method if other than guideline:

Information not available

GLP compliance:

yes

Limit test:

no

Test material

Test material information

Constituent 1

Reference substance name:

2-hexyloxyethanol

EC Number:

203-951-1

EC Name:

2-hexyloxyethanol

Cas Number:

112-25-4

Molecular formula:

C6H13OCH2CH2OH

IUPAC Name:

2-hexyloxyethanol

Details on test material:

- Name of test material (as cited in study report): Hexyl CELLOSOLVE* (Ethylene glycol monohexyl ether)
- Physical state: liquid
- Analytical purity: 98.16 %
- Stability under test conditions: Stored at room temperature
- Storage condition of test material:

Test animals

Species:

rabbit

Strain:

New Zealand White

Sex:

male/female

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Source: Charles River Laboratories, Inc. Kinston, NY
- Age at study initiation: Approximately 22 week
- Fasting period before study: None
- Housing: Rats were house 1/cage in stainless steel wire floors
- Diet: ad libitum
- Water: ad libitum
- Acclimation period: Approximately 2 week


ENVIRONMENTAL CONDITIONS
- Temperature (°F): 61°F and 70°F
- Humidity (%): 40-70 %
- Air changes (per hr): Standard conditions
- Photoperiod: (12 hrs dark / 12 hrs light)

Administration / exposure

Type of coverage:

occlusive

Vehicle:

unchanged (no vehicle)

Details on exposure:

see the attachment-1

Analytical verification of doses or concentrations:

not specified

Details on analytical verification of doses or concentrations:

No data

Duration of treatment / exposure:

Nine applications were given over a period of 11 days.

Frequency of treatment:

6/hours/day

Doses / concentrations

Doses / concentrations 1

Remarks:

Doses / Concentrations:
44 mg/kg/bw/day
Basis:
nominal per unit body weight

Doses / concentrations 2

Remarks:

Doses / Concentrations:
222 mg/kg/bw/day
Basis:
nominal per unit body weight

Doses / concentrations 3

Remarks:

Doses / Concentrations:
444 mg/kg/bw/day
Basis:
nominal per unit body weight

No. of animals per sex per dose:

5/sex/group

Control animals:

yes

Details on study design:

- Rationale for animal assignment: Random
- Post-exposure recovery period in satellite groups: None

Positive control:

no data

Examinations

Observations and examinations performed and frequency:

CAGE SIDE OBSERVATIONS: Yes


DETAILED CLINICAL OBSERVATIONS: Yes
Time schedule for examinations: Daily

DERMAL IRRITATION (if dermal study): Yes
Time schedule for examinations: Daily
BODY WEIGHT: Yes
- Time schedule for examinations: Body weights were measured immediately prior to the f i r s t dose (Day 1), one week after the first dose (Day 8), and on the day of sacrifice (Day 12).


FOOD CONSUMPTION: Yes
Food consumption data were collected for a l l animals on days 3, 5, 7, 8, 10, and 12

FOOD EFFICIENCY: No



WATER CONSUMPTION: No

OPHTHALMOSCOPIC EXAMINATION: No


HAEMATOLOGY: Yes
- Time schedule for collection of blood: prior to necropsy
- Anaesthetic used for blood collection: Yes (identity) Injections of T 61 euthansia solution
- Animals fasted: Yes
- How many animals: All animals
- Parameters checked in table [No 13,14.] were examined.


CLINICAL CHEMISTRY: Yes
- Time schedule for collection of blood: prior to necropsy
- Anaesthetic used for blood collection: Yes (identity) Injections of T 61 euthansia solution
- Animals fasted: Yes
- How many animals: All animals
- Parameters checked in table [No.15, 16] were examined.


URINALYSIS: Yes
- Time schedule for collection of urine: prior to necropsy
- Metabolism cages used for collection of urine: No
- Animals fasted: Yes
- Parameters checked in table [No.17, 18] were examined.


NEUROBEHAVIOURAL EXAMINATION: No

Sacrifice and pathology:

GROSS PATHOLOGY: Yes
HISTOPATHOLOGY: Yes
At the end of treatment, all rabbits were sacrificed by caudal ear vein injections of T61 Euthanasia Solution. Prior to sacrifice, body weights were obtained to allow expression of relative organ weights. A complete necropsy was performed on each animal. The liver, kidneys, adrenals, brain, and heart of all rabbits and the testes of all males were weighed at the time of
necropsy.

Other examinations:

Organ weights: The liver, kidneys, adrenals, brain, and heart of all rabbits and the testes of all males were weighed at the time of necropsy.

Statistics:

Food consumption, body weight, and organ weight data were intercompared for the dose and control groups by use of Levene's test for homogeneity of variances, by analysis of variance, and by pooled variance t-tests. The t-tests were used, i f the analysis of variance was significant, to delineate which groups differed from the control group. If Levene1s test indicated heterogeneous variances, the groups were compared by an analysis of variance for unequal variances followed,
if necessary, by separate variance t - tests. Non-parametric data were analyzed by the Kruskal-Wallis test or, if necessary, by the Wilcoxon rank sum test as modified by Mann-Whitney,
Frequency data were compared using Fisher's exact tests where appropriate. All statistical tests, except the frequency comparisons were performed using BMDP Statistical Software (Dixon, 1985). The frequency data tests are described in Biometry (Sokal, R. R. and Rohlf, F. J. W. H. Freeman and Company: San Francisco, 1969). The fiducial limit of 0.05 was used as the critical level of significance for all tests.

Results and discussion

Results of examinations

Clinical signs:

effects observed, treatment-related

Dermal irritation:

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:

not examined

Haematological findings:

effects observed, treatment-related

Clinical biochemistry findings:

no effects observed

Urinalysis findings:

no effects observed

Behaviour (functional findings):

not examined

Organ weight findings including organ / body weight ratios:

no effects observed

Gross pathological findings:

effects observed, treatment-related

Histopathological findings: non-neoplastic:

effects observed, treatment-related

Histopathological findings: neoplastic:

not examined

Details on results:

CLINICAL SIGNS AND MORTALITY: Treatment-related signs of toxicity observed during the study included emaciation, cold extremities, and not eating in three of 5 females from the high dose group. One female in the high dose group died on Day 9 and a second female from this treatment group was sacrificed moribund on Day 10.
Treatment area effects, other than the Draize scored erythema and edema, included dose-related increases in the incidence and/or severity of lichenification , and necrosis, observed in the mid and high dose groups of both sexes. Exfoliation occurred in all male and most female animals at all dosage levels, and fissuring occurred in most animals at the mid and high dose treatment groups for both sexes. Ecchymosis was observed for one male from the mid dose treatment group. Excoriation was noted in two males from the high dose group only, and ulceration was recorded in one male and two females from the high dose group. These lesions principally occurred during the second week of dosing. Erythema in the treatment area scored as barely perceptible (Grade 1) or well defined (Grade 2) was observed after the first day of treatment with test material for most males in the mid and high dose treatment groups (4/5 and 5/5 respectively). Erythema was first observed in the low dose treatment group of males on Day 4. The incidence of males scored with erythema at some time during the study was 4/5, 5/5, and 5/5 for the low, mid, and high dose groups, respectively with the highest incidence and severity recorded on Days 7 and 8. Edema in male rabbits treated with Hexyl CELLOSOLVE was more prominent than erythema in the male animals from the mid and high dose treatment groups. Well defined (Grade 2) to moderate (Grade 3) edema was recorded for all males in the high dose group by Day 5 with barely perceptible edema scored for two animals on Day 3. Edema was observed in 1/5 males in the mid dose group on Day 3 and all animals by Day 4. The majority of the scores for these animals were well defined (Grade 2) or moderate (Grade 3) throughout the remainder of the study. Edema, like erythema, tended to be scored higher in the middle of the study (Days 7 and 8). No edema was observed in males from the low dose group at any time during the study.

BODY WEIGHT AND WEIGHT GAIN: Weight loss (a mean of -182 g) was observed for males in the high dose group during the first week of the study compared to a weight gain of 35 g for controls. Although a slight weight gain was observed for the males in the high dose group between Days 8 and 12, the mean weight for this group was 154 g lower than the initial weight on Day 12. No treatment-related effects body weight or body weight gain was noted in males from either the low or mid dose treatment groups. Females from the high dose group also lost weight during the first week of the study with a moderate recovery observed between Days 8 and 12. The mean body weight was less than the Day 1 weights for the females from the high dose group by 523 and 403 grams, respectively on Days 8 and 12 of the study compared to gains of 27.8 and 51.5 grams observed for controls at these time intervals. No treatment-related effects were noted in females from either the low or mid dose treatment group.


FOOD CONSUMPTION: A trend toward reduced food consumption was observed for males during the first week of the study with reductions of 2.5%, 6.5% and 35.62 for the low, mid, and high dose treatment groups, respectively when compared to control values. Only the reduction in the high dose group was statistically significant. During the second week of the study, only the high dose group showed reduction in food consumption (17.62). This difference was not statistically significant. Females in the mid and high dose treatment groups showed reductions in food consumption of 7.9% and 69.7% for the first week of the study, with a 6.6% and 44.3% reduction for the second week of the study when compared to control values. The high level reduction for the first week of the study was the only value that was statistically significant.

HAEMATOLOGY: Male and female rabbits receiving 444 mg/kg/day of Hexyl CELLOSOLVE had
Statistically significant decreased erythrocyte counts (23.8% and 21.7% decreases from control, respectively), hemoglobin concentration (17.9% and IA.3% decreases, respectively), and hematocrit (.6.3% and 12.7% decreases, respectively). MCV values were increased by 11.2% for both male and female high dose animals, although only the increase in the value for males was
Statistically significant. Female rabbits in the 222 mg/kg/day group had a decreased hematocrit value (7.1% decrease) which was statistically significant. A trend for these alterations was observed in all exposure groups in males, and at least the two highest dose groups for females.

CLINICAL CHEMISTRY: There were no other treatment-related changes in serum clinical chemistry measurements for either males or females in any dose group

URINALYSIS: There were no other treatment-related changes in serum urinalysis measurements for either males or females in any dose group.

ORGAN WEIGHTS: No treatment-related differences in absolute or relative organ weights were observed for males or females from any treatment group. Males from the high dose group had elevated brain weights relative to body weight which resulted from the lower body weights for this group.


GROSS AND HISTOPATHOLOGY: Treatment-related gross and microscopic findings in rabbits surviving to the end of the study were limited to the treated skin. Microscopically, the treated skins of the majority of the rabbits in all of the Hexyl CELLOSOLVE treated groups were characterized by ancanthosis, hyperkeratosis and dermatitis. The dermatitis was ulcerative in nature in the most severely affected rabbits (primarily individual rabbits in the mid and high dose groups), and epidermal/dermal necrosis was present in the treated skins of a small number of rabbits in the high dose group. The histologic changes present in the treated skins were similar for the male and female rabbits on study. In the 2 females from the high dose group that died, gross and microscopic findings in the treatment area were similar to those in the animals that were sacrificed. No cause of death was obvious from these evaluations.

Effect levels

1

Dose descriptor:

LOAEL

Effect level:

44 mg/kg bw/day (nominal)

Based on:

test mat.

Sex:

male/female

Basis for effect level:

other: local skin irritation

2

Dose descriptor:

NOAEL

Effect level:

222 mg/kg bw/day (nominal)

Based on:

test mat.

Sex:

male/female

Basis for effect level:

other: systemic effects

Target system / organ toxicity

Critical effects observed:

not specified

Any other information on results incl. tables

None

Applicant's summary and conclusion

Conclusions:

Based on the results of this study the LOAEL for local effects is 44 mg/kg bw/day and the NOAEL for systemic effects is 222 mg/kg bw/day.

Executive summary:

New Zealand White rabbits (5/sex/group) were exposed to undiluted ethylene glycol hexyl ether by occluded cutaneous contact at doses of 0, 44, 222, or 444 mg/kg body weight/day (0, 0.05, 0.25, or 0.5 ml/kg/day). Nine applications (6 hours/day) were given over an 11-day period. A control group had water applied to the treatment site at a dose of 0.5 ml/kg/day.

 

Monitors effects included clinical observations, body weights, food consumption, hematology, clinical chemistry, urinalysis, organ weights, gross and histopathology.

 

Survivors were sacrificed the day following the final application of test material or water. One female in the high dose group died on Day 9 and a second female from this treatment group was sacrificed moribund on Day 10. The cause of death could not be determined from the evaluations performed in this study. No overt indications of treatment-related toxicity were observed, however, and death may have resulted from stress due to the skin irritation and dosing procedures used. Barely perceptible erythema was observed in male rabbits in the 44 mg/kg/day dose group. Barely perceptible to well-defined erythema was observed in males from the mid and high dose treatment levels. Graded erythema showed a dose-response relationship ranging from barely perceptible in the low dose group to moderate in the high dose group for female rabbits. Edema, scored as barely perceptible to moderate, was recorded for male rabbits in the mid and high dose levels. Graded edema showed a dose-response relationship ranging from barely perceptible in the low dose group to severe in the high dose group for females. Some individual variation in response to the irritant properties of the test material was observed. There was a tendency for the erythema and edema observed in this study to be of higher incidence and severity in the middle dosing days (particularly Days 7 and 8). Since no applications were given on Days 6 and 7, the cause of this effect is unclear.

 

The results of this study indicated that repeated percutaneous exposure of ethylene glycol hexyl ether to rabbits resulted in dose related local skin irritation at doses of 44 mg/kg/day and above.