2-(2-ethoxyethoxy)ethanol

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:

1993-1994

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: A GLP study conducted with protocol equivalent to guideline study.

Cross-reference

Reason / purpose for cross-reference:

reference to same study

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

1995

Report date:

1995

Materials and methods

Test guideline

Qualifier:

equivalent or similar to guideline

Guideline:

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

Deviations:

no

Principles of method if other than guideline:

not applicable

GLP compliance:

yes

Limit test:

no

Test material

Test material information

Constituent 1

Reference substance name:

2-(2-ethoxyethoxy)ethanol

EC Number:

203-919-7

EC Name:

2-(2-ethoxyethoxy)ethanol

Cas Number:

111-90-0

Molecular formula:

C6H14O3

IUPAC Name:

2-(2-ethoxyethoxy)ethan-1-ol

Details on test material:

- Name of test material (as cited in study report): Transcutol; Purified diethylene glycol monoethyl ether
- Physical state: Clear liquid
- Analytical purity: 100%
- Lot/batch No.: 96933
- Storage condition of test material: Room temperature

Test animals

Species:

rabbit

Strain:

New Zealand White

Sex:

male/female

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Source: Davidson's Mill Farm, S. Brunswick, NJ, USA
- Age at study initiation: no data
- Weight at study initiation: 2.2-2.5kg
- Fasting period before study: Yes approximately 16 hours prior to the initial blood collection. Due to technical error, animals were not fasted prior to blood collection at termination.
- Housing: Singly in suspended stainless steel cages.
- Diet (e.g. ad libitum): Ad libitum, Purina rabbit chow
- Water (e.g. ad libitum): ad libitum, tap water
- Acclimation period: Eight days

ENVIRONMENTAL CONDITIONS
- Temperature (°C): controlled, no further data provided
- Humidity (%): no data
- Air changes (per hr): no data
- Photoperiod (hrs dark / hrs light):12/12

IN-LIFE DATES: From: 1993, December 6 To: 1993, January 3.

Administration / exposure

Type of coverage:

occlusive

Vehicle:

unchanged (no vehicle)

Details on exposure:

TEST SITE
- Area of exposure: approximately 4x6 inch
- % coverage: no data
- Type of wrap if used: 6-ply gauze pad. Then the entire trunk of each animal was wrapped with 3 inch Durapore (3M) adhesive tape.
- Time intervals for shavings or clipplings: Clipped 24 hrs prior to initiation and as needed thereafter.

REMOVAL OF TEST SUBSTANCE
- Washing (if done): Wiped free of excess material with tap water and a clean towel.
- Time after start of exposure: 6 hours

TEST MATERIAL
- Amount(s) applied (volume or weight with unit): Specific gravity of 0.974g/ml was used to calculate application volume depending on the weight of the animal for the various doses.
- Constant volume or concentration used: no

VEHICLE
- Justification for use and choice of vehicle (if other than water): Distilled water used
- Amount(s) applied (volume or weight with unit): 2.2-3.1ml depending of weight of animal to obtain a dose of 1000mg/kg/day

USE OF RESTRAINERS FOR PREVENTING INGESTION: Yes. Animals were placed in restraint collars prior to being returned to their cages.

Analytical verification of doses or concentrations:

no

Duration of treatment / exposure:

28 consecutive days

Frequency of treatment:

6 hours per day

Doses / concentrations

Doses / concentrations 1

Dose / conc.:

100 mg/kg bw/day (actual dose received)

Remarks:

nominal per unit body weight

Doses / concentrations 2

Dose / conc.:

300 mg/kg bw/day (actual dose received)

Remarks:

nominal per unit body weight

Doses / concentrations 3

Dose / conc.:

1 000 mg/kg bw/day (actual dose received)

Remarks:

nominal per unit body weight

No. of animals per sex per dose:

5

Control animals:

yes

Details on study design:

- Dose selection rationale: no data
- Rationale for animal assignment (if not random): random
- Rationale for selecting satellite groups: no satellite groups
- Post-exposure recovery period in satellite groups: not applicable
- Section schedule rationale (if not random): not applicable

Positive control:

not applicable

Examinations

Observations and examinations performed and frequency:

DETAILED CLINICAL OBSERVATIONS: Yes
- Time schedule: Daily. Animals observed for signs of gross toxicity and/or behavioural changes once daily. Observations included gross evaluation of skin and fur, eyes and mucous membranes, respiratory, circulatory, autonomic and central nervous systems, somatomotor activity and behavior pattern.

DERMAL IRRITATION (if dermal study): Yes
- Time schedule for examinations: Immediately prior to each daily application, and 24 hours after the final appication. Following Draize scale.

BODY WEIGHT: Yes
- Time schedule for examinations: Prior to initiation and on days 7, 14, 21 and 29 (termination).

FOOD CONSUMPTION:
- Food consumption for each animal determined and individual total feed consumption (grams/rabbit) provided: Yes

HAEMATOLOGY AND CLINICAL CHEMISTRY: Yes
- Time schedule for collection of blood: prior to initiation and at termination of study
- Anaesthetic used for blood collection: No data
- Animals fasted: Yes, at initiation. Due to technical error animals were not fasted prior to blood collection at termination
- How many animals: all
- The following Haemotological parameters were examined: Hematocrit, erythrocyte count, platelet count, mean corpuscular volume, mean corpuscular hemoglobin conc., hemoglobin, leukocyte count (total and differential), mean corpuscular hemoglobin, activated partial thromboplastin time.
- The following Clinical chemistry parameters were examined: calcium, phosphorus, chloride, total protein, sodium, potassium, cholesterol, creatinine, glucose (fasting), alanine aminotransferase, aspartate aminotransferase, alkaline phosphatase, blood urea nitrogen, albumin, triglycerides, total bilirubin.

URINALYSIS: No
- Time schedule for collection of urine:
- Metabolism cages used for collection of urine: Yes / No / No data
- Animals fasted: Yes / No / No data
- Parameters checked in table [No.?] were examined.

NEUROBEHAVIOURAL EXAMINATION: No
- Time schedule for examinations:
- Dose groups that were examined:
- Battery of functions tested: sensory activity / grip strength / motor activity / other:

OTHER: no data

Sacrifice and pathology:

At terminal sacrifice, all animals were euthanized by exsanguination from the abdominal aorta under Ketamine anaesthesia. All animals were subjected to grss necropsy. Tissues and organs of the thoracic, abdominal, cranial and pelvic cavities were examined for changes in gross appearance. The following organs were removed from all animals, trimmed of fat and other contiguous tissue and weighed: adrenals, spleen, lungs, brain, kidneys, heart, liver.

Histopathology:
Histological examinations were performed on the following organs and tissues:
thyroid/parathyroid, kidneys, small intestine (duodenum), heart, ovaries, all gross lesions, lungs, brain, large intestine (colon), urinary bladder, testes, treated skin, liver, stomach, adrenals, thymus, spleen, untreated skin.

Statistics:

Means and standard deviation calculated for all quantitative data. Data for males and females within each group was evaluated separately. Test groups were compared to the control group using ANOVA. A 95% confidence level was used to determine statistically significant differences.

Results and discussion

Results of examinations

Clinical signs:

no effects observed

Description (incidence and severity):

Apart from 3 incidents (groups 1 or 3) of transient soft feces noted no other clinical signs.

Dermal irritation:

effects observed, treatment-related

Description (incidence and severity):

Treatment associated change was limited to skin. The treatment application site in the high dose rabbits had a slight response characterized by minimally thickened epithelium with a minimal increase in keratinization. The subepithelial dermis had a minimal increase of mixed leucocytes and capilalry congestion. These changes were not present in low or mid dose animals.

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):

not examined

Ophthalmological findings:

not examined

Haematological findings:

effects observed, treatment-related

Description (incidence and severity):

Mean corpuscular hemoglobin concentration (MCHC) values in the males at test termination were significantly different (p<=0.05) between test and control groups. The observed response was linearly related to the dose level: the MCHC values decreased with increasing dose. There was no significant difference in red blood cell count, hemoglobin or mean cell volume, however, insignificant decreasing dosage levels resulted in a significant difference in MCHC which is slightly suggestive of a potentially very mild macrocytic anemic response.
No statistical differences were noted in MCHC values in the females, and no other statistically significant differences in hematological findings were noted.

Clinical biochemistry findings:

effects observed, treatment-related

Description (incidence and severity):

Cholesterol values were significantly different (p<=0.05) between females of the test and control groups at study initiation. No other differences were noted.

Urinalysis findings:

not examined

Behaviour (functional findings):

not examined

Immunological findings:

not examined

Organ weight findings including organ / body weight ratios:

no effects observed

Description (incidence and severity):

No significant differences in organ to bodyweight ratios noted between groups.

Gross pathological findings:

effects observed, treatment-related

Description (incidence and severity):

Small black masses on the ovaries of 3 females from groups 1, 3, or 4 which microscopically were revealed as blood-filled follicular cysts. In the affected female from group 3, it was also noted that the left kidney was small in size, tan in color and had small black masses on its surface. In group 4, the kidneys of 2 males were either mottled tan or irregularly shaped. Tissues and organs of all other animals appeared grossly normal. Histopathological evaluation of the gross tissue abnormalities noted during necropsy revealed that these changes were not treatment related.

Histopathological findings: non-neoplastic:

no effects observed

Description (incidence and severity):

For local effects see skin irritation.

Histopathological findings: neoplastic:

no effects observed

Effect levels

1

Dose descriptor:

NOEL

Remarks:

local effects

Effect level:

100 mg/kg bw/day (nominal)

Based on:

test mat.

Sex:

male/female

Basis for effect level:

dermal irritation

2

Dose descriptor:

NOAEL

Remarks:

Local effects

Effect level:

300 mg/kg bw/day (nominal)

Based on:

test mat.

Sex:

male/female

Basis for effect level:

dermal irritation

3

Dose descriptor:

NOAEL

Remarks:

systemic effects

Based on:

test mat.

Sex:

male/female

Remarks on result:

not determinable due to absence of adverse toxic effects

Target system / organ toxicity

Critical effects observed:

not specified

Any other information on results incl. tables

No dermal irritation was noted at any of the control sites or lowest dose test group. The incidence of irritation increased as a function of dose level in the test groups. Transient, barely perceptible erythema and/or edema and desquamation was noted in most animals from groups 3 or 4 (mid and high dose groups) from days 3 onwards. Severity increased to a plateau by days 6 to 8 after which severity did not increase. Note that not all animals showed symptoms. A summary of the irritation scores are shown below:

	Mid dose group	High dose group
Number of animals affected (daily observations	1 to 4 out of 10	2 to 6 out of 10
Average score (erythema plus odema using Draize scoring method – from day 8 onwards (PII)	0.2 to 0.8	0.6 to 1.2

Applicant's summary and conclusion

Conclusions:

Under the conditions of this study a NOAEL greater than 1000mg/kg/day can be derived for systemic effects and 300mg/kg/day for local effects

Executive summary:

This is a 28 -day repeat dose dermal toxicity study with male and female rabbits in which 2 -(2 -ethoxyethoxy)ethanol was administered via the dermal route at 100, 300, or 1000mg/kg/day. The test substance was applied on consecutive days for six hours every day under occlusion. The control group received daily applications of distilled water at 1000mg/kg/day. Haematological, and clinical chemistry evaluations at initiation and termination, and gross necropsy and histopathology at terminal sacrifice were conducted. In addition, the dermal irritation reactions were evaluated following the Draize method. Under the conditions of this study the test substance did not induce toxicity at dose levels up to 1000mg/kg/day. However, the incidence of dermal irritation increased with increasing dose and microscopic examination revealed treatment associated change limited to the treated skin of the high dose rabbits. Therefore, under the conditions of this study, the NOAEL would be >1000mg/kg/day for systemic toxicity, and at 300mg/kg/day (~4.5mg/cm2) for local effects if based on histopathological changes or 100mg/kg/day if based on reversible irritation (erythema/odema).