2-(1-methylethoxy)ethyl acetate

Endpoint summary

Description of key information

Based on read-across from 2-isopropoxyethanol (CAS No. 109-59-1) and after correction for differences in molecular weight and stoichiometry of full enzymatic hydrolysis):
NOAEL oral, systemic = 8 mg/kg bw/d
NOAEC inhalation, systemic = 106 mg/m³

Key value for chemical safety assessment

Repeated dose toxicity: via oral route - systemic effects

Link to relevant study records

Reference

Endpoint:

short-term repeated dose toxicity: oral

Type of information:

migrated information: read-across from supporting substance (structural analogue or surrogate)

Adequacy of study:

key study

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: see 'Remark'

Remarks:

GLP-Guideline study, tested with the source substance 2-(1-Methylethoxy)ethanol (CAS No. 109-59-1). According to the ECHA guidance document “Practical guide 6: How to report read-across and categories (March 2010)”, the reliability was changed from RL1 to RL2 to reflect the fact that this study was conducted on a read-across substance.

Qualifier:

according to guideline

Guideline:

OECD Guideline 407 (Repeated Dose 28-Day Oral Toxicity Study in Rodents)

Deviations:

yes

Remarks:

no opthalmoscopic and neurobehavioural examinations.

GLP compliance:

yes

Limit test:

no

Species:

rat

Strain:

Crj: CD(SD)

Sex:

male/female

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Source: Charles River Japan, Inc. Atsugi
- Age at study initiation: 5 weeks
- Weight at study initiation:
- Fasting period before study: 18 h
- Housing: animals were housed individually in metallic cages with wire mesh bottoms.
- Diet: ad libitum
- Water: ad libitum
- Acclimation period: 8 days

ENVIRONMENTAL CONDITIONS
- Temperature (°C): 21-25
- Humidity (%): 40-75
- Air changes (per hr):15
- Photoperiod (hrs dark / hrs light): 12/12

Route of administration:

oral: gavage

Vehicle:

water

Analytical verification of doses or concentrations:

yes

Duration of treatment / exposure:

28 days

Frequency of treatment:

daily, 7 days/week

Remarks:

Doses / Concentrations:
0, 30, 125 and 500 mg/kg bw/day
Basis:
actual ingested

No. of animals per sex per dose:

5

Control animals:

yes, concurrent vehicle

Details on study design:

- Dose selection rationale: A preliminary test was conducted to determine the doses to be employed. Reddish urine was observed after the first administration, and inhibition of body weight gain recognized on days 1-2 at doses more than 500 mg/kg bw/d.
Based on this result, the test substance was administered in a volume of 10 mL/kg bw/d at doses of 30, 125 and 500 mg/kg bw/d by gavage for 28 days.
-Post-exposure recovery period: 14 d

Observations and examinations performed and frequency:

CAGE SIDE OBSERVATIONS: Yes
- Time schedule: twice daily, before-dosing and after-dosing and daily day during the 14 day recovery period

BODY WEIGHT: Yes
- Time schedule for examinations: twice a week and at termination administration, recovery period, and necropsy

FOOD CONSUMPTION:
- Food consumption: Yes, once a week

WATER CONSUMPTION: Yes

HAEMATOLOGY: Yes
- Time schedule for collection of blood: prior to necropsy
- Anaesthetic used for blood collection: Yes
- Animals fasted: Yes
- How many animals: 5 per sex per dose

CLINICAL CHEMISTRY: Yes
- Time schedule for collection of blood: prior to necropsy
- Animals fasted: Yes
- How many animals: 5 per sex per dose

URINALYSIS: Yes
- Time schedule for collection of urine: samples were collected for a 4 and 24 h period during the last week of administration and in the last week of the 14 d recovery period.

Sacrifice and pathology:

GROSS PATHOLOGY: Yes
Organs examined at necropsy: organ weight for both sexes, brain, lung, thyroid gland, liver, kidney, spleen, adrenal, thymus, ovaries and testes.

HISTOPATHOLOGY: Yes
All animals in control and in the high dose group: spleen, bone marrow of Femur, esophagus, liver and kidney
All animals: spleen, bone marrow of Femur, liver, kidney ovary and brain.

Statistics:

Dunnett´s test, Student´s test, Aspin-Welch´s t-test, chi square test, Mann-Whitney U-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):

no effects observed

Food efficiency:

not specified

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

no effects observed

Ophthalmological findings:

not specified

Haematological findings:

effects observed, treatment-related

Clinical biochemistry findings:

effects observed, treatment-related

Urinalysis findings:

effects observed, treatment-related

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:

effects observed, treatment-related

Histopathological findings: neoplastic:

not specified

Details on results:

CLINICAL SIGNS AND MORTALITY
No deaths in any group occurred through the administration and the recovery periods. Reddish urine was observed in both sexes from the first day of the administration until the following day at a dose of 500 mg/kg bw/day. As a result of urinary examination, this was proved to be haematuria. After the second day of administration, no clinical signs were observed.
BODY WEIGHT AND WEIGHT GAIN
There were no treatment-related changes in body weight during administration periods, however, high values of body weight continued during the recovery period in the female group at 500 mg/kg bw/day, and the value showed statistical significance on day 14 of the recovery period.
FOOD CONSUMPTION AND COMPOUND INTAKE
Food intake was significantly decreased in male and female groups at 500 mg/kg bw/day on day 1 of administration.
WATER CONSUMPTION AND COMPOUND INTAKE
There were no treatment-related changes in water consumption during the administration and recovery periods.
HAEMATOLOGY
Decreases in red cell count, haemoglobin content, haematocrit value and mean corpuscular haemoglobin concentration (MCHC), and increases in mean corpuscular volume (MCV), mean corpuscular haemoglobin (MCH), reticlulocyte were recognized in male and female groups at 500 mg/kg bw/day, and it was considered the animals were in anemic condition. Furthermore, increase of reticulocyte in males and decreases of red cell count, haemoglobin, MCHC in females were also recognized at 125 mg/kg bw/day, and it was considered the animals at this dosage were in anemic condition. Increases of MCV and MCH in both sex groups, and decrease of MCHC in males were found.
CLINICAL CHEMISTRY
Increases of inorganic phosphorus and potassium in males and increases of A/G ratio and creatinine in females were found in the group at 500 mg/kg bw/day. However, the changes of inorganic phosphorus were without change of blood calcium concentration, and the changes of potassium were without change of blood sodium, and not present in females. Therefore it was considered not to be related to treatment. Increase of total cholesterol was observed in the group at 500 mg/kg bw/day. Increase in total cholesterol was not observed at the end of the administration period, and not present in female. Therefore, it was taken as accidental changes.
URINALYSIS
In urinalysis, dark blown-coloured urine was observed in 4 males and 2 females at 500 mg/kg bw/day on day 1 of administration, and there were 8 males and 7 females including them which occult blood was strongly positive. Additionally, yellowish brown urine, protein and bilirubin were observed in both sexes at 500 mg/kg bw/day. One each of male and female animals showed strong positive occult blood at the end of the administration period (day 23 of administration). There were no treatment-related changes at the end of the recovery period (day 9 of recovery).
ORGAN WEIGHTS
Increase of absolute and relative weights of spleen were found in both sex groups at 500 mg/kg bw/day, and increase of relative weight was also found in females at 125 mg/kg bw/day. In addition, increases of relative weight of liver in both sexes, and relative weight of kidney in males were observed at 500 mg/kg bw/day. Increase of absolute weight of spleen and increase of absolute and relative weight of liver was observed in females at 500 mg/kg bw/day. Decrease in absolute weight of thyroid gland was observed in males at 500 mg/kgbw/day. However, the change of thyroid gland was not observed at the end of the administration period. Therefore, it was taken as accidental changes. Relative weight of kidney was significantly reduced due to increase of body weight measured at sacrifice.
GROSS PATHOLOGY
Enlargement of the spleen was observed in all males and 3 females, and dark reddish change of the spleen was observed in one male and 3 females at 500 mg/kg bw/day. Enlargement of the liver was observed in 2 males at 500 mg/kg bw/day, and yellowish change of the liver was observed in 3 females at 500 mg/kg bw/day. Enlargement of the kidney was observed in 3 males at 500 mg/kg bw/day. The enlargement of the spleen was examined in 2 males at 500mg/kg bw/day, and the enlargement of the liver or enlargement of the kidney was observed in these 2 examples.
HISTOPATHOLOGY: NON-NEOPLASTIC
The following changes were observed: In spleen, enhancement of extramedullary haematopoiesis in all animals of male and female groups at more than 125mg/kg bw/day, and deposition of brown pigment in almost all animals of both sex groups at more than 125 mg/kg bw/day. This brown pigment was demonstrated as hemosiderin deposition by Berlin Blue staining. In bone marrow, increased haematopoiesis of erythrocyte was found in males at 500 mg/kg bw/day and females at doses more than 125 mg/kg bw/day. In liver, extramedullary haematopoiesis was observed in 3 males and 2 females at 500 mg/kg bw/day, but such change was not found in the groups less than 125 mg/kg bw/day. Otherwise, some changes were recognized in liver and kidney; however, they were not treatment-related changes. The changes observed at the end of administration became slight.
OTHER FINDINGS
In bone marrow myelogram findings at 500 mg/kg bw/day, increase of rate of erythroid cells and decrease of rate of myeloid cells were significantly observed, Namely, increases of rates of polychromatic erythroblast in males and erythroblasts from basophilic erythroblast to normoblast in females, decreases of rates of promyeloblast, neutrophil, eosinophil and lymphocyte in males, myeloblast and eosinophilic myelocyte in females were found. As a result, the myeloid/erythroid ratio was reduced in both sexes. At doses less than 125 mg/kg bw/day, though the degree became mild as compared with the findings of the group at 500 mg/kg bw/day, some findings were observed at 125 mg/kg bw/day, and increase in rate of polychromatic erythroblast and decreases of neutrophil, eosinophil in males, and decrease of rate of myeloblast in females were observed at 30 mg/kg bw/day. After the recovery period, the changes observed at the end of administration reduced, and decrease of rate of promyelocyte was found in females, but increase of rate of neutrophilic myelocyte, myeloid/erythroid ratio were found, and these changes were opposite as compared with the findings observed at the end of the administration period.

Dose descriptor:

LOAEL

Effect level:

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

Based on:

test mat.

Sex:

male/female

Basis for effect level:

other: haematuria

Dose descriptor:

NOAEL

Effect level:

< 30 mg/kg bw/day (actual dose received)

Based on:

test mat.

Sex:

male/female

Basis for effect level:

other: haematuria

Critical effects observed:

not specified

Table 1. Results of urinalysis in male and female rats on Day 1 of the dosing period.

		Male				Female
Dose (mg/kg bw/day)		control	30	125	500	control	30	125	500
Number of animals in group		10	5	5	10	10	5	5	10
Red blood cells, not observed		10	5	5	10	10	5	5	10
Crystals, a few observed		10	4	5	9	8	5	4	10
Cast, not observed		10	5	5	10	10	5	5	10
Protein	-	5	4	3	1	8	4	5	3
	+/-	3	1	0	1	1	1	0	0
	+	2	0	2	0	1	0	0	0
	++	0	0	0	5	0	0	0	4
	+++	0	0	0	3**	0	0	0	3**
Bilirubin	-	10	5	5	2	10	5	5	5
	+	0	0	0	7	0	0	0	5**
	++	0	0	0	1	0	0	0	0
Occult blood	-	10	5	5	2	10	5	5	3
	+++	0	0	0	8	0	0	0	7**
Color	Light yellow	9	5	5	1	10	5	5	3
	Yellow	1	0	0	1	0	0	0	2
	Yellowish brown	0	0	0	4	0	0	0	3
	Dark brown	0	0	0	4**	0	0	0	2**

**: p<0.01

 - negative; ± trace; +: slight; ++: moderate; +++: marked

Table 2. Results of haematological examinations in male rats at the end of the dosing period and at the end of the recovery period.

Dose (mg/kg bw/day)	End of administration period				End of recovery period
	0	30	125	500	0	500
RBC (x10xE4/µL)	737 ± 29	720 ± 24	718 ± 31	571 ± 25**	793 ± 43	751 ± 21
Haemoglobin (g/dL)	14.7 ± 0.5	14.2 ± 0.3	14.4 ± 0.4	12.6 ± 0.5**	14.8 ± 0.4	15.0 ± 0.3
Haematocrit (%)	44.3 ± 2.0	43.2 ± 1.0	43.7 ± 1.8	39.1 ± 1.5**	44.1 ± 1.4	45.0 ± 1.2
MCV (fL)	60.1 ± 1.9	60.0 ± 1.1	60.8 ± 1.7	68.6 ± 2.9**	55.6 ± 2.5	59.9 ± 1.6*
MCH (pg)	19.9 ± 0.7	19.8 ± 0.4	20.0 ± 0.6	22.1 ± 0.9**	18.7 ± 0.8	20.0 ± 0.6*
MCHC (g/dL)	33.2 ± 0.3	33.0 ± 0.3	32.9 ± 0.4	32.2 ± 0.3**	33.6 ± 0.1	33.4 ± 0.1*
Platelet (x10xE4/µL)	100.0 ± 10.6	108.4 ± 5.7	98.6 ± 15.7	95.6 ± 14.8	99.4 ± 4.5	95.2 ± 10.3
Reticulocyte (%)	3.5 ± 0.8	3.5 ± 0.5	5.3 ± 1.4*	14.8 ± 1.3**	3.1 ± 0.6	2.7 ± 0.4
WBC (x100/µL)	88.6 ± 35.4	67.8 ± 20.9	79.7 ± 25.6	77.2 ± 32.4	101.1 ± 36.9	76.9 ± 10.7

*: p<0.05, **:p<0.01

Table 3. Results of haematological examinations in female rats at the end of the dosing period and at the end of the recovery period.

Dose (mg/kg bw/day)	End of administration period				End of recovery period
	0	30	125	500	0	500
RBC (x10xE4/µL)	724 ± 31	672 ± 55	655 ± 31*	548 ± 24**	744 ± 28	742 ± 32
Haemoglobin (g/dL)	14.4 ± 0.5	13.5 ± 0.9	13.2 ± 0.4*	12.3 ± 0.4**	14.3 ± 0.8	15.3 ± 0.6
Haematocrit (%)	42.6 ± 1.4	40.4 ± 2.7	39.9 ± 1.3	38.4 ± 1.1**	42.7 ± 2.4	45.6 ± 1.8
MCV (fL)	58.9 ± 1.3	60.2 ± 2.1	61.0 ± 1.5	70.2 ± 1.3**	57.2 ± 1.3	61.5 ± 1.2**
MCH (pg)	19.9 ± 0.5	20.1 ± 0.6	20.1 ± 0.5	22.5 ± 0.3**	19.2 ± 0.3	20.6 ± 0.5**
MCHC (g/dL)	33.7 ± 0.2	33.5 ± 0.2	33.0 ± 0.3**	32.1 ± 0.3**	33.6 ± 0.4	33.5 ± 0.4
Platelet (x10xE4/µL)	110.9 ± 4.1	108.6 ± 15.6	104.5 ± 9.6	102.3 ± 10.9	102.3 ± 11.7	99.0 ± 4.3
Reticulocyte (%)	2.2 ± 0.6	4.5 ± 4.7	5.8 ± 1.9	15.4 ± 2.5**	3.7 ± 1.6	2.1 ± 0.6
WBC (x100/µL)	43.7 ± 9.2	31.0 ± 18.2	40.7 ± 15.2	39.2 ± 8.7	48.9 ± 5.5	56.5 ± 4.0*

*: p<0.05, **:p<0.01

Table 4. Myelogram findings in male rats.

	End of administration period				End of recovery period
Dose (mg/kg bw/day)	Control	30	125	500	Control	500
Myeloblast (%)	2.2 ± 0.9	2.3 ± 0.4	2.2 ± 0.5	1.9 ± 1.3	2.5 ± 0.9	2.3 ± 1.0
Promyelocyte (%)	2.6 ± 0.9	2.8 ± 0.4	2.6 ± 0.7	1.4 ± 0.4*	3.1 ± 0.8	3.1 ± 1.4
Neutrophilic myelocyte (%)	5.4 ± 1.0	6.0 ± 0.5	7.2 ± 2.4	5.0 ± 1.0	8.2 ± 1.9	6.5 ± 1.8
Neutrophil (%)	25.8 ± 1.8	21.7 ± 2.1**	19.3 ± 1.7**	16.3 ± 1.7**	22.9 ± 4.9	22.7 ± 5.4
Eosinophilic myelocyte (%)	1.0 ± 0.5	1.0 ± 0.4	1.2 ± 0.5	0.9 ± 0.6	0.6 ± 0.4	0.9 ± 0.3
Eosinophil (%)	1.6 ± 0.5	0.7 ± 0.3*	0.8 ± 0.7*	0.5 ± 0.3**	0.9 ± 0.6	0.6 ± 0.2
Total granulocyte(%)	50.3 ± 1.5	47.5 ± 3.4	43.5 ± 2.9**	35.4 ± 3.2**	48.7 ± 6.4	48.1 ± 7.5
Basophilic erythroblast (%)	2.8 ± 1.1	3.7 ± 1.1	3.4 ± 1.1	6.3 ± 4.1	4.5 ± 1.3	4.8 ± 2.8
Polychromatic erythroblast (%)	11.9 ± 2.4	15.8 ± 1.0*	17.1 ± 2.8**	25.2 ± 2.4**	11.8 ±2.2	12.7 ± 3.0
Normoblast (%)	14.1 ± 4.1	13.4 ± 2.3	14.4 ± 4.5	17.5 ± 3.1	13.0 ± 2.2	11.6 ± 3.0
Total erythroblast(%)	29.0 ± 2.5	32.9 ± 2.5	35.2 ± 5.8*	49.4 ± 3.0**	29.9 ± 4.6	29.5 ± 8.3
Myeloid/Erythroid	1.8 ± 0.2	1.4 ± 0.2*	1.3 ± 0.3**	0.7 ± 0.1**	1.7 ± 0.4	1.8 ± 0.8
Lymphocyte	17.2 ± 2.6	17.0 ± 2.9	17.9 ± 4.7	11.5 ± 2.6*	18.3 ± 3.5	18.2 ± 4.8

*: p< 0.05, **:p<0.01

Table 5. Myelogram findings in female rats.

	End of administration period							End of recovery period
Dose (mg/kg bw/day)	Control	30		125			500	Control	500
Myeloblast (%)	3.8 ± 0.9		1.3 ± 0.8**		1.4 ± 0.3**	1.5 ± 1.3**		1.7 ± 0.9	2.6 ± 0.8
Promyelocyte (%)	2.2 ± 1.1		2.8 ± 0.9		2.7 ± 0.6	1.4 ± 0.8		3.5 ± 0.7	2.5 ± 0.3*
Neutrophilic myelocyte (%)	5.8 ± 0.9		7.1 ± 1.5		5.2 ± 2.2	5.7 ± 2.2		6.1 ± 1.2	8.0 ± 1.2*
Neutrophil (%)	19.9 ± 5.6		18.4 ± 2.0		18.3 ± 4.1	15.7 ± 2.8		20.3 ± 4.8	23.6 ± 1.6
Eosinophilic myelocyte (%)	1.7 ± 0.6		1.6 ± 0.2		1.0 ± 0.3*	0.6 ± 0.3**		1.5 ± 0.5	1.4 ± 0.4
Eosinophil (%)	1.0 ± 0.5		1.1 ± 0.4		0.8 ± 0.4	0.8 ± 0.3		1.5 ± 0.4	1.4 ± 0.6
Total granulocyte(%)	45.0 ± 6.8		44.0 ± 3.9		41.9 ± 5.2	34.4 ± 5.6*		46.9 ± 4.5	51.5 ± 3.4
Basophilic erythroblast (%)	3.6 ± 1.6		4.8 ± 1.7		2.0 ± 0.9	6.4 ± 2.2*		3.3 ± 1.7	2.8 ± 1.0
Polychromatic erythroblast (%)	13.2 ± 3.8		15.2 ± 2.7		16.8 ± 5.3	21.9 ± 2.4**		13.4 ± 1.4	10.5 ± 3.3

*: p< 0.05, **:p<0.01

Endpoint conclusion

Endpoint conclusion:

adverse effect observed

Dose descriptor:

NOAEL

8 mg/kg bw/day

Study duration:

subacute

Species:

rat

Quality of whole database:

The available information comprises adequate, reliable (Klimisch score 2) and consistent studies from a reference substance with similar structure and intrinsic properties. Read-across is justified based on structural similarity between the source and target substances, the source substance being a product of the hydrolysis of the target substance (refer to endpoint discussion for further details).
The selected study is thus sufficient to fulfil the standard information requirements set out in Annex VIII-IX, 8.6, in accordance with Annex XI, 1.5, of Regulation (EC) No 1907/2006.

Repeated dose toxicity: inhalation - systemic effects

Link to relevant study records

Reference

Endpoint:

sub-chronic toxicity: inhalation

Type of information:

migrated information: read-across from supporting substance (structural analogue or surrogate)

Adequacy of study:

key study

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: see 'Remark'

Remarks:

Comparable to guideline study with acceptable restrictions. No detailed clinical and ophthalmoscopic examinations were performed. Body weight determination, clinical chemistry and haematology analysis only performed in selected animals. Histopathological examination was only performed in 10 animals per sex of the control, 50 and 200 ppm group. Not all recommended standard clinical pathology parameters and organ weights were examined.

Qualifier:

equivalent or similar to guideline

Guideline:

OECD Guideline 413 (Subchronic Inhalation Toxicity: 90-Day Study)

Deviations:

yes

Remarks:

no detailed clinical and ophthalmoscopic examinations; body weights, clinical chemistry and haematology parameters not determined in all animals; histopathological examination only in 10 animals per sex of the control, 50 and 200 ppm group

GLP compliance:

no

Limit test:

no

Species:

rat

Strain:

other: Carworth Farms E-strain (CFE)

Sex:

male/female

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Source: Tunstall Laboratory
- Age at study initiation: 12-13 weeks
- Weight at study initiation:
- Fasting period before study: animals were fasted prior to every exposure.
- Housing: animals were housed in groups of 4 per cage during acclimatisation. During the entire study, animals were kept in groups of 40 per sex and chamber.
- Diet: ad libitum
- Water: ad libitum
- Acclimation period: 3 weeks

ENVIRONMENTAL CONDITIONS
- Temperature (°C): 17.2-19.4
- Humidity (%): not controlled

Route of administration:

inhalation: vapour

Type of inhalation exposure:

whole body

Vehicle:

air

Remarks on MMAD:

MMAD / GSD: Not applicable.

Details on inhalation exposure:

GENERATION OF TEST ATMOSPHERE / CHAMBER DESCRIPTION
- Exposure apparatus: 10 m³ stainless steel inhalation chamber
- Method of conditioning air:
- System of generating vapours: test atmospheres were generated by vaporising the solvent in an induced air flow to produce a concentrated vapour/air mixture which was then diluted to the desired concentration by the main air flow into the chamber. The vaporizer was a quartz-sheathed heating element wound with glass fibre tape to increase the surface area, and the solvent was fed onto this surface from a solvent reservoir by means of a micro-metering pump. The vaporiser was mounted vertically inside a 4 inch nominal bore section of industrial glass pipeline which was connected by means of a 90° bend to the inlet duct of the exposure chamber. This generation system was designed so that the vaporiser had a minimum solvent hold-up. This meant that at the end of the 6 hour exposure period when the micro-metering pump ceased solvent delivery, solvent vapours quickly cleared from the generator and the concentration of solvent in the test chamber rapidly decreased to zero.
- Temperature, humidity, pressure in air chamber: 17.2-19.4 °C
- Air flow rate: 3.5 m³/min (top dose chamber) and 4.3 m³/min (other 3 dose chambers)

TEST ATMOSPHERE
- Brief description of analytical method used: a Beckman 109A Total Hydrocarbon analyser was used for continuous monitoring of the test atmosphere during the exposure period and a Beckman GC 2A gas chromatograph fitted with a flame ionisation detector and an auto gas sampling valve was used to analyse the test atmosphere from each of the three chambers the daily exposure period.
- Samples taken from breathing zone: yes

VEHICLE
- Concentration of test material in vehicle: 25, 50, 200 ppm (v/v)

Analytical verification of doses or concentrations:

yes

Details on analytical verification of doses or concentrations:

Two different analysis systems were used in this experiment. One system, comprising two Beckman 109A Total Hydrocarbon analysers, enabled a continuous monitoring of the test atmospheres to be carried out during the exposure period. These analysers quickly responded to changes made in the atmosphere generation system and/or total chamber air flow rate, so that adjustments could be made to maintain the desired concentration of toxicant in the test atmospheres. This was particularly useful during the start-up period.
The other system consisted of a Beckman GC 2A gas chromatograph (GC) fitted with a flame ionization detector and an auto gas sampling valve. Test atmosphere from each of the three chambers in turn was drawn continuously through the gas sampling system, and a sample was transferred to the column every 6 min. The peak heights were averaged over the sampling period of approximately 75 min. The instrument was calibrated by means of an exponential dilution technique using a 12.5 litre stirred gas flask.
The three test atmospheres were analysed during the daily exposure period on both of the analysis systems, so that while continuous signals were obtained from the two Total Hydrocarbon analysers for two or the test atmosphere, the third atmosphere was being repeatedly chromatographed on the Beckman GC 2A. In this way, the concentrations of the solvent in the three test atmospheres could be determined, and any deviations from the desired values could be quickly spotted. The mean concentrations and ranges of solvent in the test atmospheres over the complete exposure period were 24 (16 to 30) ppm (v/v), 47 (32 to 56) ppm (v/v), and 197 (169 to 230 ) ppm (v/v).

Duration of treatment / exposure:

26 weeks

Frequency of treatment:

6 h/day, 5 days/week

Remarks:

Doses / Concentrations:
25, 50, 200 ppm (v/v)
Basis:
nominal conc.

Remarks:

Doses / Concentrations:
0.106, 0.212 and 0.850 mg/L
Basis:
other: nominal concentration based on a molecular weight of 104.15 g/mol and a molar gas volume of 24.5 L/mol

Remarks:

Doses / Concentrations:
106, 212 and 850 mg/m³
Basis:
nominal conc.

Remarks:

Doses / Concentrations:
24, 47 and 197 ppm (v/v)
Basis:
analytical conc.

No. of animals per sex per dose:

40

Control animals:

yes, concurrent vehicle

Observations and examinations performed and frequency:

CAGE SIDE OBSERVATIONS: Yes
- Time schedule: animals were observed daily for general health and behaviour.

DETAILED CLINICAL OBSERVATIONS: No

BODY WEIGHT: Yes
- Time schedule for examinations: body weights were determined once weekly in 22/40 animals per sex and group at Weeks 0, 1, 2, 9, 10, 12, 18, 21, 23 and 26, respectively.

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

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

WATER CONSUMPTION: No

OPHTHALMOSCOPIC EXAMINATION: No

HAEMATOLOGY: Yes
- Time schedule for collection of blood: at Weeks 0, 5, 9, 13, 18, 22 and 26
- Anaesthetic used for blood collection: No data
- Animals fasted: No data
- How many animals: 12/40 animals per sex and dose at Week 0; 1-3/40 animals per sex at Weeks 5, 9, 13, 18 and 22; 22/40 animals per sex and dose at Week 26
- Parameters checked: haemoglobin (Hb), packed cell volume (PCV), red blood cell count (RBC), white blood cell count (WBC), mean corpuscular volume (MCV), mean corpuscular haemoglobin (MCH), mean corpuscular haemoglobin concentration (MCHC), PT (prothrombin time), KCCT (kaolin cephalin coagulation time), osmotic fragilities

CLINICAL CHEMISTRY: Yes
- Time schedule for collection of blood: at Weeks 0, 5, 9, 13, 18, 22 and 26
- Animals fasted: No data
- How many animals: 12/40 animals per sex and dose at Week 0; 2-4/40 animals per sex at Weeks 5, 9, 13, 18 and 22; 20-22/40 animals per sex and dose at Week 26
- Parameters checked: protein, urea, ALP (alkaline phosphatase), SGPT (Serum glutamic pyruvic transaminase), SGOT (serum glutamic oxaloacetic transaminase), sodium (Na), potassium (K), chloride (Cl)

URINALYSIS: No

NEUROBEHAVIOURAL EXAMINATION: No

Sacrifice and pathology:

GROSS PATHOLOGY: Yes, all animals.
HISTOPATHOLOGY: Yes, in 10 randomly selected rats per sex of the control, 50 and 200 ppm group (brain, heart, kidney, lung, spleen, liver, alimentary tract, pancreas, salivary gland, thymus, mesenteric lymph node, gonads, prostate or uterus, pituitary, adrenals, larynx, thyroid, eye and decalcified sections of nasal cavities).
Organ weights of brain, heart, liver, spleen, kidneys and testes were determined in 20-22 animals per sex and group.

Statistics:

Body weights and organ weights were analysed by covariance analysis using initial body weight as the covariate. Reported means were adjusted for initial body weight if a significant covariance relationship existed. Where no significant covariance relationship existed, means were reported unadjusted. Covariance analysis was also used with terminal body weight as the covariance to test whether organ weight differences could be attributed to the differences in terminal body weight or if differences in organ weight were concealed by body weight variation. Reported means were adjusted for terminal body weight if a significant covariance relationship existed. This is not a true covariance analysis since terminal body weights are dependent upon treatment and has only been reported when it aids the interpretation of body and organ weight difference. Clinical chemical and haematological parameters were examined using analysis of variance. The significance of any differences between treatment and control group means was tested using the Williams t-test. However, on some occasions a monotonic dose response relationship could not be assumed, in which case Dunnett’s test was used.

Clinical signs:

no effects observed

Mortality:

no mortality observed

Body weight and weight changes:

no effects observed

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:

effects observed, treatment-related

Description (incidence and severity):

25, 50 and 200 ppm: sign. increase in 50% osmotic fragility of erythrocytes and decrease in MCH/MCHC; 50 and 200 ppm: sign. increase in 100% osmotic fragility of erythrocytes, sign. decrease in MCH and MCHC; 200 ppm: sign. decrease in RBC, Hb and PCV

Clinical biochemistry findings:

effects observed, treatment-related

Description (incidence and severity):

25, 50 and 200 ppm: significant decrease in potassium levels

Urinalysis findings:

not examined

Behaviour (functional findings):

not examined

Organ weight findings including organ / body weight ratios:

effects observed, treatment-related

Description (incidence and severity):

200 ppm: significant increase in relative spleen weight

Gross pathological findings:

no effects observed

Histopathological findings: non-neoplastic:

effects observed, treatment-related

Histopathological findings: neoplastic:

no effects observed

Description (incidence and severity):

50 and 200 ppm: excessive amounts of hemosiderin in red and white pulp of spleen (m, f); 200 ppm: increase in brown pigment in Kupffer cells of liver (f), extramedullary haematopoiesis in spleen (m, f)

Details on results:

CLINICAL SIGNS AND MORTALITY
No treatment-related clinical signs and mortalities were observed.

BODY WEIGHT AND WEIGHT GAIN
Mean body weights were similar between all treated animals and controls.

HAEMATOLOGY
At 200 ppm, a consistent and significant reduction in haemoglobin concentration was observed in male and female rats, which was accompanied by a marginal reduction in packed cell volume (PCV) and a consistently lower erythrocyte count (RBC) during the entire study period. A consistent and significant elevated mean corpuscular volume (MCV) in the male and female rats exposed to 200 ppm was also noted. Small rises in erythrocyte counts and occurred in both male and female rats at 25 and 50 ppm, being indicative of a compensatory regeneration of erythrocytes at the lower dose levels, which however, was not sufficient to compensate the loss in erythrocytes at the highest dose level, as shown by the significant decrease in RBC and haemoglobin compared to controls. Changes in the osmotic fragility of rat erythrocytes occasionally occurred at all exposure levels, indicating a greater susceptibility of erythrocytes to haemolysis. At 25 ppm, the 50% osmotic fragility was statistically significant at Week 22 (p < 0.05) in male rats and at Week 13 (P < 0.05) and Week 18 (p < 0.01) in female rats. At the higher dose levels (50 and 200 ppm), the 50 and 100% osmotic fragility of erythrocytes was statistically significantly increased (p < 0.01) in both males and females at the end of the exposure period (26 weeks). At the same dose levels, mean corpuscular haemoglobin (MCH) and mean corpuscular haemoglobin concentration (MCHC) were significantly decreased compared to controls in both genders, providing further evidence for the treatment-related haemolytic effects after inhalative exposure.
In addition to the haemolytic effects, a slight reduction in kaolin cephalin coagulation time (KCCT) was observed in male and females at 200 ppm, which was not considered to be of toxicological relevance.

CLINICAL CHEMISTRY
At week 26 (study termination), plasma potassium values were significantly and dose-related decreased in both genders at all dose levels. No further significant changes in clinical parameters were observed.

ORGAN WEIGHTS
The relative weights of spleens were significantly increased in male and female rats exposed to 200 pm compared to controls. There is a correlation between increased spleen weight and the histological changes noted at the 200 ppm exposure level. In males exposed to 200 ppm, relative heart weights were significantly higher and relative liver were significantly lower compared to controls.

GROSS PATHOLOGY
No test-substance-related findings were observed at necropsy.

HISTOPATHOLOGY: NON-NEOPLASTIC
Treatment-related histopathological changes were mainly observed in liver and spleen of animals exposed to200 ppm. Considerable amounts of brown pigment were observed in Kupffer cells of the liver of female rats at 200 ppm, which could be may also be attributable to hemosiderin exposition. In males of the same dose group, small amounts of lipid in the liver parenchyma were only seen in 2/10 animals. Excessive amounts of hemosiderin were noted in the red and white pulp of the spleen in male and female rats of the 50 ppm and 200 ppm groups, respectively. Furthermore, extramedullary haematopoiesis was observed in the spleen of male and female rats exposed to 200 ppm. The accumulation of hemosiderin in spleen and possibly also in liver, as well as the extramedullary haematopoiesis in spleen are further indicative of haemolytic effects and thus correlate with the observed adverse changes in haematological parameters.

Dose descriptor:

LOAEC

Effect level:

25 ppm (nominal)

Based on:

test mat.

Sex:

male/female

Basis for effect level:

other: haematology (haemolytic effects): significant increase in the 50% osmotic fragility in erythrocytes and significant decrease in MCH and MCHC; clinical signs: significant decrease in potassium levels

Dose descriptor:

LOAEC

Effect level:

0.106 mg/L air (nominal)

Based on:

test mat.

Remarks:

corresponding to 106 mg/m³

Sex:

male/female

Basis for effect level:

other: nominal concentration based on a molecular weight of 104.15 g/mol and a molar gas volume of 24.5 L/mol

Critical effects observed:

not specified

Table 1. Osmotic fragilities of erythrocytes in male rats

Week No.	Atmosphere concentration [ppm]	No. of rats	Male
			Osmotic fragilities % NaCl producing haemolysis
			0%	50%	100%
0	0	3	0.611	0.403	0.213
	25	3	0.611	0.389	0.233
	50	3	0.622	0.393	0.200
	200	3	0.590	0.390	0.200
	Standard deviation of a single observation		0.0251	0.0162	0.0115
5	0	2	0.720	0.470	0.230
	25	3	0.632	0.455	0.203
	50	3	0.695	0.466	0.195
	200	3	0.760	0.515*	0.257
	Standard deviation of a single observation		0.0425	0.0148	0.0230
9	0	3	0.662	0.382	0.173
	25	3	0.732	0.383	0.135
	50	3	0.730	0.407	0.179
	200	3	0.722	0.463**	0.175
	Standard deviation of a single observation		0.0421	0.0187	0.0309
13	0	3	0.660	0.369	0.117
	25	3	0.665	0.427	0.160
	50	3	0.682	0.427	0.128
	200	3	0.717	0.473**	0.160*
	Standard deviation of a single observation		0.0307	0.0304	0.0203
18	0	2	0.645	0.350	0.113
	25	3	0.673	0.397	0.118
	50	3	0.657	0.398	0.130
	200	3	0.713*	0.467**	0.114
	Standard deviation of a single observation		0.0246	0.0339	0.0198
22	0	3	0.660	0.375	0.193
	25	3	0.700	0.433*	0.163
	50	3	0.725**	0.428*	0.210
	200	3	0.744**	0.480**	0.178
	Standard deviation of a single observation		0.0254	0.0256	0.0349
26	0	22	0.694	0.398	0.284
	25	22	0.708	0.400	0.274
	50	22	0.726**	0.431**	0.306**
	200	22	0.754**	0.478**	0.317**
	Standard deviation of a single observation		0.0361	0.0223	0.0218

Statistical significance is indicated at *p <0.05 and **p<0.01.

Table 2. Osmotic fragilities of erythrocytes in female rats

Week No.	Atmosphere concentration [ppm]	No. of rats	Female
			Osmotic fragilities % NaCl producing haemolysis
			0%	50%	100%
0	0	3	0.620	0.441	0.283
	25	3	0.623	0.444	0.210*
	50	3	0.662	0.443	0.210*
	200	3	0.655	0.443	0.230
	Standard deviation of a single observation		0.0288	0.0126	0.0329
5	0	3	0.608	0.463	0.248
	25	3	0.713**	0.490	0.217
	50	3	0.708**	0.505*	0.255
	200	3	0.799**	0.550**	0.171**
	Standard deviation of a single observation		0.0231	0.0159	0.0266
9	0	3	0.677	0.433	0.190
	25	3	0.697	0.431	0.158
	50	2	0.760**	0.450	0.180
	200	3	0.767**	0.523**	0.190
	Standard deviation of a single observation		0.0149	0.0296	0.0353
13	0	3	0.653	0.402	0.145
	25	3	0.707	0.428*	0.165
	50	3	0.730*	0.437*	0.150
	200	3	0.774**	0.507**	0.167
	Standard deviation of a single observation		0.0303	0.0131	0.322
18	0	1	0.661	0.390	0.160
	25	3	0.663	0.423**	0.150
	50	3	0.643	0.443**	0.153
	200	3	0.750*	0.493**	0.150
	Standard deviation of a single observation		0.735	0.528	0.188
22	0	3	0.662	0.420	0.157
	25	3	0.663	0.407	0.168
	50	3	0.715	0.448	0.227*
	200	3	0.735*	0.528**	0.188*
	Standard deviation of a single observation		0.0339	0.0336	0.0259
26	0	3	0.671	0.396	0.266
	25	3	0.723	0.420	0.266
	50	3	0.722	0.452**	0.307
	200	3	0.747**	0.488**	0.289
	Standard deviation of a single observation		0.0924	0.0565	0.0515

Statistical significance is indicated at *p <0.05 and**p<0.01.

Conclusions:

Based on the haemolytic effects observed at 25, 50 and 200 ppm (0.106, 0.212 and 0.850 mg/L), the substance is classified as STOT RE 1, H372, inhal, blood.

Endpoint conclusion

Endpoint conclusion:

adverse effect observed

Dose descriptor:

LOAEC

106 mg/m³

Study duration:

subchronic

Species:

rat

Quality of whole database:

The available information comprises adequate, reliable (Klimisch score 2) and consistent studies from a reference substance with similar structure and intrinsic properties. Read-across is justified based on structural similarity between the source and target substances, the source substance being a product of the hydrolysis of the target substance (refer to endpoint discussion for further details).
The selected study is thus sufficient to fulfil the standard information requirements set out in Annex VIII-IX, 8.6, in accordance with Annex XI, 1.5, of Regulation (EC) No 1907/2006.

Repeated dose toxicity: inhalation - local effects

Endpoint conclusion

Endpoint conclusion:

no adverse effect observed

Repeated dose toxicity: dermal - systemic effects

Endpoint conclusion

Endpoint conclusion:

no study available

Repeated dose toxicity: dermal - local effects

Endpoint conclusion

Endpoint conclusion:

no study available

Additional information

Justification for grouping of substances and read-across

There are no data available on repeated dose toxicity of 2-(1-methylethoxy)ethyl acetate (CAS 19234-20-9). In order to fulfil the standard information requirements set out in Annex IX, 8.6, in accordance with Annex XI, 1.5, of Regulation (EC) No 1907/2006, read-across from structurally related substances is conducted.

In accordance with Article 13 (1) of Regulation (EC) No 1907/2006, "information on intrinsic properties of substances may be generated by means other than tests, provided that the conditions set out in Annex XI are met.” In particular for human toxicity, information shall be generated whenever possible by means other than vertebrate animal tests, which includes the use of information from structurally related substances (grouping or read-across).

Having regard to the general rules for grouping of substances and read-across approach laid down in Annex XI, Item 1.5, of Regulation (EC) No 1907/2006, whereby physicochemical, toxicological and ecotoxicological properties may be predicted from data for reference substance(s) by interpolation to other substances on the basis of structural similarity, 2-isopropoxy-ethanol (CAS 109-59-1) and acetic acid (CAS 64-19-7) are selected as reference substances for assessment of the repeated dose toxicity of 2-(1-methylethoxy)ethyl acetate.

The read-across is based on the metabolism of 2-(1-methylethoxy)ethyl acetate, in particular on the fact that the substance undergoes enzymatic ester hydrolysis resulting in the formation of 2-isopropoxy-ethanol and acetic acid. A detailed analogue approach justification is provided in the technical dossier (see IUCLID Section 13).

Overview of repeated dose toxicity

CAS #	19234-20-9	109-59-1	64-19-7
Chemical name	2-(1-methyl-ethoxy)ethyl acetate	2-isopropoxy-ethanol	Acetic acid
Molecular weight	146.18	104.15	60.05
Repeated dose toxicity, oral	RA: CAS 109-59-1 and CAS 64-19-7	Experimental result: LOAEL = 8 mg/kg bw/d (subacute)	Experimental result: NOAEL = 445 mg/kg bw/d (subchronic)
Repeated dose toxicity, inhalation	RA: CAS 109-59-1	Experimental result: LOAEC = 0.106 mg/L air (6h) (subchronic)	--

(a) The substance subject to registration is indicated in bold font.

(b) Reference (read-across) substances are indicated in normal font. Lack of data for a given endpoint is indicated by “--“.

 

oral

The repeated oral dose toxicity in rats was conducted under OECD TG 407 in compliance with GLP (MHLW, 2003). 2-(1-Methylethoxy) ethanol was administered orally by gavage to male and female rats (5 or 10 animals/sex/group) for 28 days at doses of 0 (vehicle control), 30, 125 and 500 mg/kg bw/day. Five each of male and female animals were allocated as recovery groups after 28 days repeated doses for the control and 500 mg/kg bw/day groups. No deaths were observed through the administration and the recovery periods. As general signs, reddish urine was found in both sexes from the first day of administration until the next day at 500 mg/kg bw/day, and as a result of urinalysis this change was proved to be haematuria. There were no treatment-related changes in body weights in either sex, however, high values continued during recovery period in females at 500 mg/kg bw/day, and the value showed statistical significance on day 14 of recovery. Food intake was significantly decreased on day 1 of administration in both sex groups at 500 mg/kg bw/day. In urinalysis, dark brown-coloured urine was observed in several male and female rats on day 1 of administration at 500 mg/kg bw/day. Of those several male and female rats, most of the animals showed strong positive response for occult blood. One each of male and female animals showed strong positive response for occult blood at the end of administration period (day 23 of administration), but none of animals showed positive response at the end of recovery period (day 9 of recovery). Besides, yellowish brown urine, urinary protein and bilirubin were observed in both sexes at 500 mg/kg bw/day. In the haematological examination, anemia like changes were recognized in male and female animals of 500 mg/kg bw/day at the end of the administration period. The changes consisted of decreases in red cell count, haemoglobin content, haematocrit value, MCHC (mean corpuscular haemoglobin concentration), and increases in MCV (mean corpuscular volume), MCH (mean corpuscular haemoglobin), reticulocyte. Some of these findings were also found in both sexes at 125 mg/kg bw/day. At the end of the recovery period, increases of MCV and MCH in both sexes and decrease of MCHC in males were observed. In bone marrow myelogram findings, increases of the rate of erythroid cells (polychromatic erythroblast, basophilic erythroblast, and normoblast) and decreases of the rate of myeloid cells (myeloblast, promyelocyte, neutrophilic myelocyte, neutrophil, eosinophilic myelocyte, and eosinophil). Thus the myeloid/erythroid ratio was decreased in male and/or female animals at 500 mg/kg bw/day. Of these, increase in the rate of the polychromatic erythroblast, decreases in rates of neutrophil, eosinophil and myeloid/erythroid ratio in males and decrease in rate of myeloblast in females at 125 mg/kg bw/day were also observed at 30 mg/kg bw/day. At the end of the recovery period, most of the myelogram changes seen in the administration period disappeared. In blood biochemical examination at the end of administration period, increases in A/G ratio and creatinine in females were found in the group at 500 mg/kg bw/day. These changes disappeared at the end of the recovery period. In organ weights at the end of administration period, increase in absolute and relative weights of spleen was found in both sexes at 500 mg/kg bw/day and increase in relative weight was also found in females at 125 mg/kg bw/day. Furthermore, increases in relative weight of liver in both sexes and relative weight of kidney in males were observed. Changes in weight of spleen and liver were also found at the end of the recovery period. In gross pathological findings at the end of administration period, enlargement and dark reddish change of the spleen were observed in males and females at 500 mg/kg bw/day. Enlargement of the liver was observed in males at 500 mg/kg bw/day. Yellowish change of the liver was observed in females at 500 mg/kg bw/day. Enlargement of the kidney was observed in males at 500 mg/kg bw/day. The enlargement of the spleen, liver and kidney was observed in males at 500 mg/kg bw/day at the end of the recovery period. In histopathological findings at the end of the administration period, treatment-related changes were observed at spleen and femur bone marrow. Changes found in spleen involved enhancement of extramedullary haematopoiesis and deposition of brown pigment which was proved as hemosiderin by Berlin blue staining. The former change was observed in almost all animals of both sex groups at 125 mg/kg bw/day and higher. In bone marrow, increased haematopoiesis of erythrocyte was found in males at 500 mg/kg bw/day and females at more than 125 mg/kg bw/day. In histopathology at the end of the recovery period, the changes observed at the end of the administration period became slight. As described above, treatment-related changes observed as critical findings consisted of occult blood and bilirubin in urinalysis, anemia like changes in haematology, increased erythroid cells and decreased myeloid cells in the bone marrow myelogram, increased weight of spleen, and histopathological findings in spleen and bone marrow. These findings were recognized in male and female groups at 500 mg/kg bw/day, and some of the findings were also at 125 mg/kg bw/day. The findings in the bone marrow myelogram were observed in both sex groups at 30 mg/kg bw/day. From these results, the dose of 30 mg/kg bw/day in this study was considered LOAEL.

 

A reproductive and developmental toxicity screening test was conducted under OECD TG421 in compliance with GLP (MHLW, 2003). 2-(1-methylethoxy) ethanol was administered orally by gavage to rats (13 animals/sex/group) at 0 (vehicle control), 8, 30 and 125 mg/kg bw/day. Males were dosed from 14 days before mating to the day before scheduled sacrifice through the mating period (total 48 days). Females were dosed from 14 days before mating to 3 days after delivery through mating and gestation periods (total 41-47 days). Males were sacrificed and necropsied on day 49. Females were sacrificed and necropsied on day 4 of lactation. With regard to systemic general toxicity, no deaths occurred, however, reddish urine (haematuria) was observed after approximately 4 hrs after dosing on the first day of administration. Seven males and all females in the group at 125 mg/kg bw/day and one female at 30 mg/kg bw/day showed reddish urine, but no abnormalities were observed after the second day in any group. No change was observed in body weight in treated groups of both sexes. Food intake was slightly decreased only on days 1-2 in the male group at 125 mg/kg bw/day. At necropsy, enlargement of spleen was found in two male animals at 125 mg/kg bw/day. Absolute and relative weights of spleen were increased in both sex groups at 125 mg/kg bw/day. In two male animals enlargement of spleen was found, and extramedullary hematopoiesis and deposition of brown pigment were recognized in histopathology. Thus, hematuria, organ weight and pathological change in spleen were observed at 125 mg/kg bw/day, and this dose was considered adverse level for general toxicity in males. At 30 mg/kg bw/day, one female showed haematuria. Although increase in hematuria was not statistically significant, it was considered to be dose responsive. The NOAELs of this study were considered to be 30 mg/kg bw/day in males and 8 mg/kg bw/day in females. The LOAELs of this study were considered to be 125 mg/kg bw/day in males and 30 mg/kg bw/day in females.

 

Another repeated dose toxicity test was conducted in pigs with the test material acetic acid (Lamb 1941). Young pigs from a single litter were divided into groups of 2 and fed basal diet (control group) or basal diet plus addition of acetic acid. The dose level was raised every 10-30 days from approximately 155 mg/kg/day to 380-450 mg/kg/day after 60 days. The pigs were weighed during the study and urine samples were taken at intervals to determine ammonia content. At the end of the study blood samples were taken for pH measurement. Following a 30 day period on basal diet, the test group received acetic acid daily, in the diet, starting at a dose of approximately 155 mg/kg/day. Doses were increased every 10 or 30 days until a maximum of 380-450 mg/kg/day was reached after 60 days. Pigs were then maintained on this dose for 3 months, except during period 5 when lactic acid was fed instead of acetic acid. There were no mortalities and no effects on body weight or acid-base balance in pigs fed acetic acid, at doses of up to 450 mg/kg/day, for approximately 6 months. The NOAEL of this study was considered to be 450 mg/kg bw/day (limit dose).

 

Inhalation

2-(1-Methylethoxy)ethanol was studied for subchronic (26-week) inhalation toxicity studies in four animal species (dog, rabbit, guinea pig, rat) at concentrations of 0, 25, 50, or 200 ppm (0, 0.1075, 0.215, and 0.86 mg/L; 0, 107.5, 215, and 860 mg/m3) for 26 weeks, 6 hrs/day, 5 days/week (Moffett et al., 1976). Numbers of animal used were 40 rats/sex/dose, 2 rabbits/sex/dose, 30 guinea pigs/sex/dose and 2 dogs/sex/dose.

In the rat study, decrease in haemoglobin concentration, and packed cell volume, and increase in mean cell volume were observed in the male and female rats in the 200 ppm group. Changes in the osmotic fragility of rat erythrocytes occurred on occasions at all exposure levels. At 25 ppm exposure level the 50% osmotic fragility was only statistically significant at week 22 in male rats and at week 13 and week 18 in female rats. No differences between control and 25 ppm treatment group were found at week 26, the end of the study. Significant decrease in plasma potassium was observed in both sexes in the 25, 50 and 200 ppm groups at week 26. Increase in the spleen weight was observed in male and female rats in the 200 ppm group. Increase in the heart weight and decrease in liver weight were observed in male rats in the 200 ppm group. In the histopathological examination, amounts of brown pigment in kupffer cells of the liver were observed in female rats in the 200 ppm group. Excessive amounts of hemosiderin in the red and white pulp of the spleen were observed in male and female rats in the 50 ppm and 200 ppm groups. Extramedullary haematopoiesis was observed in the spleen of rats in the 200 ppm group. Small amounts of lipid in the liver parenchyma were observed of male rats in the 200 ppm group. Haemolytic effects occurred marginally at the 25 ppm and clearly at the 50 and 200 ppm. The osmotic fragility of the erythrocytes of rats was significantly changed at the 25, 50 and 200 ppm. In rabbits, aggressive and hyperexcitable behaviours were observed during week 14 in both sex in the 200 ppm group. Increase in kidney weight was observed in male rabbits in the 200 ppm. In guinea pigs, increased in SGOT was observed in females in the 200 ppm group. In dogs, diarrhoea contaminated with slight trace of blood and increase in heart weight were observed in males in the 200 ppm group. The NOAECs for repeated dose inhalation toxicity in rabbits, guinea pigs and dogs were considered to be 50 ppm. Based on haemolytic effect in rats, the LOAEC for repeated dose inhalation toxicity was considered to be below 25 ppm in rats.

 

Conclusion for repeated dose toxicity

In both the inhalation toxicity and the oral administration toxicity studies conducted with the analogue substance 2-(1-methylethoxy)ethanol (CAS 109-59-1), haemolytic effects were observed. In the inhalation toxicity study, the osmotic fragility of the erythrocytes of rats was significantly changed at 25 ppm and higher. Based on this effect, the LOAEC for inhalation repeated dose toxicity was determined to be 25 ppm in rats. In the oral toxicity study, increase of erythroid cells and decrease of myeloid cells in the bone marrow myelogram were observed even in both sex groups at 30 mg/kg bw/day. In the reproductive and developmental toxicity study, haematuria, organ weight and pathological change in spleen were observed at 125 mg/kg bw/day in both sexes. Haematuria was also observed at 30 mg/kg bw/day in females. Although increase in haematuria was not statistically significant, it was considered to be dose responsive. Based on these results, the NOAEL for repeated dose oral toxicity was considered to be 8 mg/kg bw/day.

A repeated dose toxicity study cunducted with the analogue substance acetic acid (CAS 64-19-7) resulted in a NOAEL of >/= 450 mg/kg bw/d (limit dose) and thus no hazard was identified.

 

For the purpose of hazard assessment of 2-(1-methylethoxy)ethyl acetate, the lowest dose descriptors available from the source substances are selected as starting point: 2-(1-methylethoxy)ethanol: LOAEL oral = 30 mg/kg bw/d (MHLW, 2003); LOAEC inhalation = 25 ppm = 106 mg/m³ (Moffett et al., 1976).

Enzymatic ester hydrolysis of 2-(1-methylethoxy)ethyl acetate is anticipated to take place in the gastrointestinal tract and in the lung prior to absorption of the substance. It cannot be ruled out, that the parent substance or a fraction of it may be absorbed unchanged and be hydrolysed within the body, e.g. in the liver. Therefore, in a worst case approach, 100% hydrolysis and bioavailability of 2-(1-methylethoxy)ethyl acetate is assumed. In order to correct the dose descriptor for differences in molar mass, it is thus assumed that hydrolysis of 1 mole 2-(1-methylethoxy)ethyl acetate (146.18 g) results in the formation of 1 mole 2-(1-methylethoxy)ethanol (104.15 g).

Hence, the LOAEL oral of 2-(1-methylethoxy)ethyl acetate is estimated to be 42.1 mg/kg bw/d (= 30 mg/kg bw/d x [146.18/104.15]). This effect level serves as the dose descriptor starting point for derivation of the long-term systemic DNELs for the oral and the dermal route. The LOAEC inhalation of 2-(1-methylethoxy)ethyl acetate is estimated to be 148.8 mg/m³ (=106 mg/m³ x [146.18/104.15]). This effect level serves as the dose descriptor starting point for derivation of the long-term systemic DNELs for the inhalation route. The DNELs are provided in section 7, Toxicological information.

Justification for selection of repeated dose toxicity via oral route - systemic effects endpoint:
Hazard assessment is conducted by means of read-across from structural analogues/surrogates. The selected study is the most adequate and reliable study based on the identified similarities in structure and intrinsic properties between source and target substances and overall assessment of quality, duration and dose descriptor level (refer to the endpoint discussion for further details).

Justification for selection of repeated dose toxicity inhalation - systemic effects endpoint:
Hazard assessment is conducted by means of read-across from structural analogues/surrogates. The selected study is the most adequate and reliable study based on the identified similarities in structure and intrinsic properties between source and target substances and overall assessment of quality, duration and dose descriptor level (refer to the endpoint discussion for further details).

Repeated dose toxicity: via oral route - systemic effects (target organ) cardiovascular / hematological: hematopoiesis

Repeated dose toxicity: inhalation - systemic effects (target organ) cardiovascular / hematological: hematopoiesis

Justification for classification or non-classification

Based on read-across from a structurally related substance and following an analogue approach, and after correction of the dose descriptor for differences in molar mass, the available data on the repeated dose toxicity (LOAEC inhalation, subchronic, vapour = 0.106 mg/L) meet the classification criteria to classify 2-(1-methylethoxy)ethyl acetate as STOT RE Category 1 according to Regulation (EC) 1272/2008 or as R48/20/22 according to Directive 67/548/EEC.