2-[2-(dimethylamino)ethoxy]ethanol

Repeated dose toxicity: inhalation

Administrative data

Endpoint:

short-term repeated dose toxicity: inhalation

Type of information:

experimental study

Adequacy of study:

supporting study

Study period:

1989-05-08 to 1993-04-19

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: The GLP study was conducted according to labortory specific protocols and methods similar to OECD guideline study methods.

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

1993

Report date:

1993

Materials and methods

Test guideline

Qualifier:

no guideline followed

Guideline:

other: The protocol and protocol amendments detailing the design and conduct of this study are laboratory specific methods (BRRC Project No. 89-15-50507) and in compliance with the following guidelines and standards: EPA TSCA.

Principles of method if other than guideline:

Four groups, each consisting of 10 Sprague Dawley rats per sex, were exposed for 6 hours per day for 9 exposures over an 11-day period to vapor of the test substance. An additional 5 rats per sex were added to the control and high concentration groups to be held for 2 weeks after the final exposure in order to determine the reversibility of any induced toxicity. Target concentrations of the test substance were 0 (control), 5, 25, and 60 ppm. Monitors for toxic effects included clinical observations, food and water consumption, ophthalmic examination, body and organ weights, hematologic and serum clinical chemistry evaluations, urinalysis and urine chemistry evaluations, and macroscopic and microscopic evaluations.

GLP compliance:

yes

Limit test:

no

Test material

Test material information

Constituent 1

Reference substance name:

2-[2-(dimethylamino)ethoxy]ethanol

EC Number:

216-940-1

EC Name:

2-[2-(dimethylamino)ethoxy]ethanol

Cas Number:

1704-62-7

Molecular formula:

C6H15NO2

IUPAC Name:

2-[2-(dimethylamino)ethoxy]ethan-1-ol

Details on test material:

- Name of test material (as cited in study report): 2-[2-(dimethylamino)ethoxy]ethanol
- Molecular formula (if other than submission substance): (CH3)2NCH2CH20CH2CB2OH
- Molecular weight (if other than submission substance): 133.2
- Substance type: Pure active substance
- Physical state: The test substance was a transparent, pale yellow liquid with a slight amine odor.
- Analytical purity: 97%
- Composition of test material, percentage of components: Prestudy analysis: Unknown components totalled 630.4 ppm, DMEA 0.245%, VOE 0.228%, A-99 0.366%, Ethylene glycol 0.632%, and VOEE 0.943% and DMEE 97%; Poststudy analysis: Unknown components totalled 515.4 ppm, DMEA 0.233%, VOE 0.222%, A-99 0.361%, Ethylene glycol 0.635%, and VOEE 0.951% and DMEE 97%.
- Storage condition of test material: The test substance was blanketed with nitrogen during storage.

Test animals

Species:

rat

Strain:

Sprague-Dawley

Sex:

male/female

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Source: Harlan Sprague Dawley, Inc. (Frederick, MD)
- Age at study initiation: Regular test group animals were 35 days old; satalite group animals were 42 days old.
- Weight at study initiation: Regular test group animals were 125-149 g for males and 100-124 g for females at arrival; satalite group animals were 150-174 g.
- Fasting period before study: N/A
- Housing: Housed 1 or 2 per cage in stainless steel, wire-mesh cages (23.5 cm x 20 cm x 18 cm).
- Diet (e.g. ad libitum): Powdered, certified AGWAY PROLAB@ Animal Diet Rat, Mouse, Hamster 3200 was available ad libitum except during
exposures.
- Water (e.g. ad libitum): Tap water (Municipal Authority of Westmoreland County, Greensburg, PA) was av ailable ad libitum except during exposures.
- Acclimation period: 3 weeks for the animals from the first shipment (regular test group animals) and 2 weeks for the animals from the second shipment (satalite group animals).

ENVIRONMENTAL CONDITIONS
- Temperature (°C): 18.3-25 deg C
- Humidity (%):40-70%
- Air changes (per hr): 13 air changes per hour (as specified during exposure)
- Photoperiod (hrs dark / hrs light): 12-hour photoperiod (approximately 0500 to 1700 hours for the light phase).

IN-LIFE DATES: From: 1989-05-08 To: 1989-06-09 (Regular test group animals)
IN-LIFE DATES: From: 1989-15-08 To: 1989-06-23 (Satalite test group animals)

Administration / exposure

Route of administration:

inhalation: vapour

Type of inhalation exposure:

whole body

Vehicle:

air

Remarks on MMAD:

MMAD / GSD: N/A

Details on inhalation exposure:

GENERATION OF TEST ATMOSPHERE / CHAMBER DESCRIPTION
- Exposure apparatus: The chambers were constructed from stainless steel with glass windows for animal observation, were rectangular (60.2 x 101 x 101 cm) in shape with a pyramidal top and bottom, with a volume of 900 liters.
- Method of holding animals in test chamber: whole body test chamber
- Source and rate of air: N/A
- Method of conditioning air: N/A
- System of generating particulates/aerosols: Liquid test substance was metered from a syringe pump (2.5 ml for the 5 ppm exposure chamber, 25 ml for the 25 ppm exposure chamber or a piston pump (G-6 FMI pump for the 60 ppm exposure chamber; into a heated glass evaporator.
- Temperature, humidity, pressure in air chamber: The temperature in the evaporator was maintained at the level sufficient to vaporize the test substance. Evaporator temperatures were determined without test substance on Days 1 and 6 following the 6-hour exposure period using a thermocouple attached to a digital recorder. The evaporator temperatures ranged from 49-61 deg C.
- Air flow rate: 200 L/min
- Air change rate: 13 air changes per hour
- Method of particle size determination: N/A
- Treatment of exhaust air: N/A

TEST ATMOSPHERE
- Brief description of analytical method used: N/A
- Samples taken from breathing zone: no

VEHICLE (if applicable)
- Justification for use and choice of vehicle: filtered air
- Composition of vehicle: N/A
- Type and concentration of dispersant aid (if powder): N/A
- Concentration of test material in vehicle: N/A
- Lot/batch no. of vehicle (if required): N/A
- Purity of vehicle: N/A

Analytical verification of doses or concentrations:

yes

Details on analytical verification of doses or concentrations:

A Dwyer Magnehelic pressure gauge was used to monitor chamber airflow. The theoretically-derived time (t99) required for each chamber to reach 99% of the target concentration was calculated to be 20.7 minutes. Chamber concentrations of the test substance vapor were analyzed by flame ionization gas chromatography. At least 3 samples from each exposure chamber and 1 sample from the control chamber were obtained during the 6-hour exposure period. The nominal concentration was calculated by dividing the total amount of vapor delivered to the chamber by the total airflow.

Duration of treatment / exposure:

9 days

Frequency of treatment:

6 hours per day for 9 exposures over an 11-day period (Animals were exposed for 6 hours per day for 5 consecutive days. After 2 days without exposure, the animals were exposed for an additional 4 consecutive days.)

Doses / concentrations

Doses / concentrations 1

Remarks:

Doses / Concentrations:
0, 5, 25, and 60 ppm
Basis:
nominal conc.

Doses / concentrations 2

Remarks:

Doses / Concentrations:
3.1, 18.9, and 42.7 ppm
Basis:
analytical conc.

No. of animals per sex per dose:

10/sex/dose

Control animals:

yes, concurrent vehicle

Details on study design:

- Dose selection rationale: A previous acute inhalation study was conducted in Sprague Dawley rats (BRRC Report No 52-67). In this study, animals were exposed to 72 and 63 ppm of the test substance vapor generated by dynamic bubbler and evaporator methods, respectively, or to 15 ppm of of the test substance vapor, generated by a static method. One female rat died on Exposure Day 1 following the static exposure. No mortality was observed following the dynamic exposures.
- Rationale for animal assignment (if not random): Animals were assigned to 3 exposure groups and a control group using a nonstratified randomization procedure based on body weight. At the time of group assignment, only animals with body weights within +/- 20% of the population mean for each sex were included.
- Rationale for selecting satellite groups: N/A
- Post-exposure recovery period in satellite groups: 2 weeks
- Section schedule rationale (if not random): N/A

Positive control:

N/A

Examinations

Observations and examinations performed and frequency:

CAGE SIDE OBSERVATIONS: Yes
- Time schedule: During the exposures, observations were recorded on a group basis. Preceding and following each exposure, observations were recorded for animals exhibiting overt clinical signs.
- Cage side observations checked: Overt clinical signs.

DETAILED CLINICAL OBSERVATIONS: Yes
- Time schedule: At the time of body weight collection and just preceding sacrifice.

BODY WEIGHT: Yes
- Time schedule for examinations: Body weights were measured on the morning prior to initiation of the first exposure (denoted as Day 1 in the tables), preceding the second, fifth, sixth, and seventh exposures, and immediately preceding sacrifice. The animals were weighed weekly during the 2-week recovery period.

FOOD CONSUMPTION:
- Food consumption for each animal determined and mean daily diet consumption calculated as g food/kg body weight/day: Yes; Food consumption was measured over an approximate 15-hour period following the eighth exposure of male rats and the ninth exposure of female rats (excluding the animals designated for the 2-week recovery period).

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: Yes
- Time schedule for examinations: Water consumption was measured over an approximate 15-hour period following the eighth exposure of male rats and the ninth exposure of female rats (excluding the animals designated for the 2-week recovery period).

OPHTHALMOSCOPIC EXAMINATION: Yes
- Time schedule for examinations: Prior to the first exposure, the eyes of all rats were examined by a Clinical Veterinarian by direct ophthalmoscopy following dilation of eyes with MYDRIACYL 1% (tropicamide 1.0%) Ophthalmic Solution. Following the ninth exposure, the eyes of all rats were again examined by a Veterinary Ophthalmologist by indirect ophthalmoscopy and/or slit lamp biomicroscopy following dilation of eyes with a tropicamide solution.
- Dose groups that were examined: All rats

HAEMATOLOGY: Yes
- Time schedule for collection of blood: Prior to sacrifice
- Anaesthetic used for blood collection: methoxyflurane
- Animals fasted: No data
- How many animals: All rats (excluding those designated for the 2-week recovery period).
- Parameters checked: Hematocrit, mean corpuscular hemoglobin concentration (MCHC), hemoglobin, erythrocyte count, total leukocyte count, mean corpuscular volume (MCV), differential leukocyte and reticulocyte smears, mean corpuscular hemoglobin (MCH), and platelet count.

CLINICAL CHEMISTRY: Yes
- Time schedule for collection of blood: Prior to sacrifice
- Animals fasted: No data
- How many animals: All rats (excluding those designated for the 2-week recovery period).
- Parameters checked: Glucose, urea nitrogen, creatinine, total protein, albumin, globulin (calculated), total bilirubin, direct bilirubin, indirect bilirubin (calculated), calcium, phosphorus, sodium, potassium, chloride, carbon dioxide,
aspartate aminotransferase (AST), alanine aminotransferase (ALT), creatine kinase (CK), lactate dehydrogenase (LDH), gamma-glutamyl transferase (GGT), sorbitol dehydrogenase (SDH), alkaline phosphatase (ALK).

URINALYSIS: Yes
- Time schedule for collection of urine:
- Metabolism cages used for collection of urine: Yes
- Animals fasted: No data
- Parameters checked: osmolality, PH, protein, semi-quantitative, quantitative, glucose, ketones, bilirubin, blood, urobilinogen, total volume, color and appearance, sediment, sodium, creatinine, chloride, potassium.

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

OTHER: N/A

Sacrifice and pathology:

GROSS PATHOLOGY: Yes; A complete necropsy was performed on all animals. The liver, heart, spleen, brain, lungs, kidneys, and testes (males) were weighed for all sacrificed animals.

HISTOPATHOLOGY: Yes; The following tissues were collected and retained in 10% neutral buffered formalin or Bouin's fixative: gross lesions*, lungs*, nasal turbinates*, brain, thymus*, trachea*, heart*, liver*, larynx*, spleen*, kidneys*, adrenal gland, testes*, ovaries, skin (ears, nares, and eyelids)*, lymph node- submandibular*, eyes*.

Tissues (with *) from animals in the control and high concentration groups (excluding those designated for the 2-week recovery period) were processed histologically and examined microscopically.

In addition, the nasal cavity, nares, and skin around the eyes and ears, which were determined to be target tissues, were examined microscopically from animals in the 5 and 25 ppm groups and from animals designated for the recovery group.

Other examinations:

N/A

Statistics:

The data for quantitative continuous variables were intercompared for the three exposure groups and the control group by use of Levene's feet 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 variances, all groups were compared by an ANOVA for unequal variances followed, when necessary, by a separate variance t-test for pairwise comparisons.

Nonparametric data were statistically evaluated using the Kruskal-Wallis test followed by the Mann-Whitney U-test when appropriate. Incidence data were compared using Fisher's Exact Test. For all statistical tests, the probability value of 0.05 (two-tailed) was used as the critical level of significance.

Various models of calculators, computers, and computer programs may have been used to analyze data for this study. Since various models round or truncate
numbers differently, values in some tables may differ slightly from those in other tables or from independently calculated data. The integrity of the study and interpretation of the data were unaffected by these differences.

Results and discussion

Results of examinations

Clinical signs:

effects observed, treatment-related

Description (incidence and severity):

See results below

Mortality:

mortality observed, treatment-related

Description (incidence):

See results below

Body weight and weight changes:

no effects observed

Description (incidence and severity):

N/A

Food consumption and compound intake (if feeding study):

no effects observed

Description (incidence and severity):

N/A

Food efficiency:

not examined

Description (incidence and severity):

N/A

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

no effects observed

Description (incidence and severity):

N/A

Ophthalmological findings:

effects observed, treatment-related

Description (incidence and severity):

See results below

Haematological findings:

no effects observed

Description (incidence and severity):

N/A

Clinical biochemistry findings:

effects observed, treatment-related

Description (incidence and severity):

See results below

Urinalysis findings:

effects observed, treatment-related

Description (incidence and severity):

See results below

Behaviour (functional findings):

not examined

Description (incidence and severity):

N/A

Organ weight findings including organ / body weight ratios:

no effects observed

Description (incidence and severity):

N/A

Gross pathological findings:

effects observed, treatment-related

Description (incidence and severity):

See results below

Histopathological findings: non-neoplastic:

effects observed, treatment-related

Description (incidence and severity):

See results below

Histopathological findings: neoplastic:

no effects observed

Description (incidence and severity):

N/A

Details on results:

CLINICAL SIGNS AND MORTALITY
Perinasal encrustation was observed in all males and females of the 42.7 ppm exposure group. No other exposure-related clinical signs were observed.

BODY WEIGHT AND WEIGHT GAIN
No statistically significant differences in absolute body weight were observed in males or females of any exposure group. Body weight gains for males in the 18.9 and 42.7 ppm groups were slightly decreased during the exposure regimen; the decreases in the 42.7 ppm group were statistically significant at the end of the exposure regimen. These decreases in body weight gain may be related to the exposure; however, a concentration-response relationship was not observed. No statistically significant differences in body weight gain were observed in females of any exposure group.

FOOD CONSUMPTION
No statistically significant differences in food consumption were observed in males or females of any exposure group.

FOOD EFFICIENCY
N/A

WATER CONSUMPTION
No statistically significant differences in water consumption were observed in males or females of any exposure group.

OPHTHALMOSCOPIC EXAMINATION
Corneal crystals were observed in eyes of most males and females in the control and exposure groups. Only minimal corneal crystals were observed in the control and low exposure groups. Increases in the severity of corneal crystals were observed in the higher exposure groups showing mild (18.9 ppm exposure group) or mild to moderate (42.7 ppm exposure group) corneal crystals

HAEMATOLOGY
No statistically significant differences in hematology parameters were observed in males. In females, statistically significant increases in total leukocytes, segmented neutrophils, and lymphocytes were observed for the 42.7 ppm group.

CLINICAL CHEMISTRY
A statistically significant increase in carbon dioxide levels was observed in the males exposed to 42.7 ppm of the test substance vapor. The carbon dioxide level in females of the 42.7 ppm group was slightly increased, although not statistically significantly. No other exposure-related effects in clinical chemistry were observed.

URINALYSIS
Statistically significant decreases in urine volume and pH were observed in males of the 42.7 ppm group. Statistically significant increases in urine creatinine and decreases in creatinine clearance were also observed in males of the 42.7 ppm group. There were no differences noted for any urinary parameters or urine chemistry determinations for DMEE-exposed females.

NEUROBEHAVIOUR


ORGAN WEIGHTS
No exposure-related effects on organ weights were observed in any exposure group at the end of the exposure regimen or at the end of the 2-week recovery period. Statistically significant decreases in heart weight and heart weight relative to body weight were observed in males of the 18.9 ppm group at the end of the exposure regimen; however, these decreases were not considered to be related to the exposure due to the lack of a concentration-response relationship.

GROSS PATHOLOGY
Exposure-related microscopic findings were observed on the skin around the eyes, on the ears, and in the nares of both males and females of the 42.7 ppm group. These findings include epithelial vacuolation with some necrosis or degeneration, reactive hyperplasia (acanthosis), inflammation (dermatitis, rhinitis, conjunctivitis), and scab formation (eschar). Epithelial vacuolation, without much evidence of the more advanced degenerative and inflammatory reactions, was observed in the nares of males and females of the 18.9 ppm group. The skin on the ears was also affected in animals of the 18.9 ppm group. The only other microscopic findings observed were rhinitis and epithelial vacuolization/degeneration of the anterior sections of the nasal cavity, primarily in the 18.9 and 42.7 ppm groups. Rhinitis was observed in 1/10 female of the 3.1 ppm group, and epithelial vacuolation was observed in 1/10 other female of the 3.1 ppm group. Some of the microscopic findings observed in the ears and anterior nasal cavity at the end of the exposure regimen were noted in a few male rats after the 2-week recovery period.

HISTOPATHOLOGY: NON-NEOPLASTIC
The only exposure-related gross lesion observed at the necropsy at the end of the exposure regimen was the appearance of a crust on the nares of 8/10 males and all females exposed to 42.7 ppm of the test substance vapor. This lesion was not apparent at the necropsy at the end of the 2-week recovery period.

HISTOPATHOLOGY: NEOPLASTIC (if applicable)
N/A

HISTORICAL CONTROL DATA (if applicable)
N/A

OTHER FINDINGS
N/A

Effect levels

1

Dose descriptor:

NOEC

Effect level:

3.1 ppm

Based on:

test mat.

Sex:

male

Basis for effect level:

histopathology: non-neoplastic

ophthalmological examination

2

Dose descriptor:

NOEC

Effect level:

3.1 ppm

Based on:

test mat.

Sex:

female

Basis for effect level:

histopathology: non-neoplastic

ophthalmological examination

Target system / organ toxicity

Critical effects observed:

not specified

Applicant's summary and conclusion

Conclusions:

exposure of rats to the test substance vapor for 9 exposures over an 11-day period produced clinical and necropsy observations indicative of nasal irritation (42.7 ppm group only), effects on body weight gain (males only), increased blood carbon dioxide levels, and ophthalmologic findings (corneal crystals) at concentrations of 18.9 and 42.7 ppm. Histologic lesions in the nasal cavity were noted in animals of the 18.9 and 42.7 ppm groups and also in 2/10 female rats of the lowest concentration group. Thus, a no-observed effect concentration of 3.1 ppm was noted for males; however, for females, 3.1 ppm was a marginal effect concentration, but appeared to be close to a no observed-effect concentration.