Reaction mass of 2-methylpentane and Hexanol, branched and linear and diisopropyl ether

Endpoint summary

Description of key information

The test item has the main constituent of isopropyl ether (approximately 50%). Minor constituents comprise propylene dimers (approximately 20% C6 hydrocarbons, mainly C6 alkenes), propylene trimers (approximately 10% C9 hydrocarbons), hexanols (approximately 10%) and C3 alcohols (approximately 10% consisting of both isopropanol and n-propanol). Read across from diisopropylether (DIPE) and other constituents is justified on the basis that NOAECs reported for the constituents of this UVCB range from 3500 mg/m³ for hexanol to 31680 mg/m³ for propylene dimers, which can be considered indicative of low toxicity for this UVCB substance. DIPE comprises approximately 50% of the UVCB substance and is, therefore, the main constituent. The C6 alkanes/alkenes are, with 20%, the second largest constituent. A regulatory design 90-day toxicity study in rats (Dalbey and Feuston, 1996) was conducted via the inhalation route with a vaporised sample of commercial grade DIPE for 6 hours/day and 5 days/week. The study included both untreated and sham-exposed controls and groups treated at 480, 3300 or 7100 ppm DIPE (equivalent to 2000, 13800 and 29700 mg DIPE/m³). DIPE itself accounted for 91-95% of the vapours and resulted in some renal and hepatotoxicity at the treatment levels of 3300 and 7100 ppm with males being more severely affected than females and organ weight changes only associated with pathological changes at the 7100 ppm level. The treatment level of 480 ppm was without effect. At these moderately toxic exposure levels in a 90-day toxicity setting in rats, the read-across substance, DIPE, demonstrated a No Observed Adverse Effect Concentration (NOAEC) via the inhalation route of exposure of 3300 ppm (equivalent to 13800 mg/m³).

Key value for chemical safety assessment

Toxic effect type:

dose-dependent

Repeated dose toxicity: via oral route - systemic effects

Endpoint conclusion

Endpoint conclusion:

no study available

Repeated dose toxicity: inhalation - systemic effects

Link to relevant study records

Reference

Reference 1

Endpoint:

sub-chronic toxicity: inhalation

Type of information:

experimental study

Adequacy of study:

key study

Study period:

1996

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

guideline study with acceptable restrictions

Reason / purpose for cross-reference:

reference to same study

Qualifier:

equivalent or similar to guideline

Guideline:

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

Deviations:

yes

Remarks:

-Some observations/parameters were not reported for certain organs; food and water consumption not reported

GLP compliance:

no

Limit test:

no

Species:

rat

Strain:

other: Sprague-Dawley-derived rats [Tac:N(SD)fBR]

Sex:

male/female

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Source: Single shipment from Taconic Farms, German-town, N.Y.
- Age at study initiation: approximately 8 weeks
- Housing: Individually housed in 1-cubic meter (H-1000) inhalation chambers; untreated control animals were housed in a separate animal room in the same caging.
- Diet: ad libitum, except during exposure; certified Purina rodent chow 5002
- Water: ad libitum, except during exposure
- Acclimation period: 2 weeks


ENVIRONMENTAL CONDITIONS
- Temperature (°C): 20-22 °C
- Humidity (%): 40-60%
- Photoperiod (hrs dark / hrs light): 12h/12h

Route of administration:

inhalation: vapour

Type of inhalation exposure:

whole body

Vehicle:

other: unchanged (no vehicle)

Remarks on MMAD:

MMAD / GSD: Not applicable

Details on inhalation exposure:

GENERATION OF TEST ATMOSPHERE / CHAMBER DESCRIPTION
- Exposure apparatus: three 1 cubic meter, H1000 exposure chambers
- Source and rate of air: Filtered room air combined with air stream containing diisopropyl ether generate by evaporation from a heated (46 °C) wick. The wick surrounded a stainless steel tube and the wick and tube were enclosed in a 5.08 cm glass pipe through which HEPA-filtered room air flowed at approximately 290 Ipm.
- Temperature, humidity, pressure in air chamber: 23-24 °C, 60-67%, monitored every 30 min
- Air change rate: at least 12 per hour
- Treatment of exhaust air: filtered through charcoal beds

TEST ATMOSPHERE
- Brief description of analytical method used: 50-250 µL samples injected directly to a Hewlett-Packard 5880A gas chromatograph (GC) with flame ionization detector (FID) and fused silica column (30 m, 0.53 mm ID, 1 µm film). The helium carrier flow was 5 mL/min with 27 mL/min makeup air; oven temperature at 40 °C for 10 mininutes followed by a ramp at 4 °C/min to 200 °C. The GC calibration was done with known volumes vapourised in 500 mL glass sampling flask. In addition, periodic samples were taken and analysed by GC/ mass spectroscopy (MS) with mass spectrum scanned from 35 to 200 amu.

Analytical verification of doses or concentrations:

yes

Details on analytical verification of doses or concentrations:

480 ppm: 2000 ±200 mg/cubic meter, 480±48 ppm; Total hydrocarbons: 2100 ±200 mg/cubic meter (95 ±4 weight% diisopropyl ether)
3300 ppm: 13800 ±900 mg/cubic meter, 3300±215 ppm; Total hydrocarbons: 14900 ±1100 mg/cubic meter (92 ±2 weight% diisopropyl ether)
7100 ppm: 29700 ±1600 mg/cubic meter, 7100±383 ppm; Total hydrocarbons: 32600 ±2000 mg/cubic meter (91 ±2 weight% diisopropyl ether)

In GC/MS analysis the sample comprised approximately 86-87% diisopropyl ether, with the remaining 13-14% comprising of more than 20 alkanes, alkenes, cycloalkanes, ketones, alcohols in the range C3-C9; a trace amount of toluene was also present.

Duration of treatment / exposure:

13 weeks

Frequency of treatment:

6-hour exposure per day, 5 exposure days per week

Remarks:

Doses / Concentrations:
480 ppm (2000 mg/cubic meter)
Basis:
nominal conc.

Remarks:

Doses / Concentrations:
3300 ppm (13800 mg/cubic meter)
Basis:
nominal conc.

Remarks:

Doses / Concentrations:
7100 ppm (29700 mg/cubic meter)
Basis:
nominal conc.

No. of animals per sex per dose:

14 animals per sex per dose

Control animals:

yes, concurrent no treatment

yes, sham-exposed

Details on study design:

- Dose selection rationale: Review of available literature data on toxicity. Due to safety considerations, the upper dose was selected to be approximately half the lower explosive limit of the substance.
- Untreated control remained in a separate animal room. Apart from routine animal care, body weights and clinical observations, they were not handled.
- Sham control were treated the same as the diisopropyl ether group except actual exposure.

Positive control:

No positive control was used.

Observations and examinations performed and frequency:

CAGE SIDE OBSERVATIONS: Yes
- Time schedule: daily except weekends

DETAILED CLINICAL OBSERVATIONS: Yes
- Time schedule: daily except weekends

BODY WEIGHT: Yes
- Time schedule for examinations: weekly

FOOD CONSUMPTION: No

FOOD EFFICIENCY: No

WATER CONSUMPTION: No

OPHTHALMOSCOPIC EXAMINATION: No

HAEMATOLOGY: Yes
- Time schedule for collection of blood: at sacrifice
- Anaesthetic used for blood collection: yes; light ether
- Animals fasted: yes; after last exposure, fasted overnight before sampling
- How many animals: all
- Parameters checked: white blood cell (WBC), red blood cell (RBC), hemoglobin (Hb), hematocrit (Hct), mean corpuscular volume (MCV), mean corpuscular hemoglobin (MCH), mean corpuscular hemoglobin concentration (MCHC), platelets, and differential cell count.

CLINICAL CHEMISTRY: Yes
- Time schedule for collection of blood: at sacrifice
- Animals fasted: yes; after last exposure, fasted overnight before sampling
- How many animals: all
- Parameters checked: glucose, urea nitrogen, total protein, globulin (G), albumin (A), A:G ratio, sorbital dehydrogenase, aspartate aminotransferase, alanine aminotransferase, alkaline phosphatase, creatinine, cholesterol, total bilirubin, triglycerides, uric acid, potassium (K), sodium (Na), chloride (Cl), calcium (Ca), and phosphorus (P) using Hitachi blood analyser 704.

URINALYSIS: No

NEUROBEHAVIOURAL EXAMINATION: No

Sacrifice and pathology:

The animals were sacrificed over several days during the 14th week. Exposures and control animals were continued during this period.
GROSS PATHOLOGY: Yes
The following organs were examined and weighed when present: adrenals, kidney, spleen, brain, liver, testes, epididymides, ovaris, thymus, heart, prostate, and uterus. In addition, the weight of the right middle lung lobe was measured after drying at 90 °C.

HISTOPATHOLOGY: Yes
The following tissues, from sham and high dose groups, were examined and preserved in buffered 10% formalin: adrenals ovaries, sternum, pancreas, brain (three sections), salivary gland, eye, optic nerce, spleen, heart, stomach, colon, testes, duodenum, thymus, kidneys, thyroid, liver, lymph nodes (tracheobronchial, anterior mediastinal, cervical), lung (left lobe), nasal turbinates, thigh muscle, skin (six sites), urinary bladder, sciatic nerve, seminal vesicals, preputial glands, and gross lesions.
The following tissues, from untreated and remaining groups, were examined and preserved in buffered 10% formalin: lungs, tracheobronchial lymph nodes, and gross lesions.
Finally, the male 14600 mg/cubic meter group also had slides prepared for liver and kidneys.

Other examinations:

Testis and associated tissues were preserved in 10% formalin for all groups.
From the two control groups and the high dose group, 10 animals were selected and the left cauda epididymis examined for sperm morphology and number. The left testis was used for weight and spermatid number.
Methodology: morphology (Wyrobek, A.J., Mutat. Res., 1983, 115, 1-72), number of sperm and spermatids (Blazak, W.F., Fundam. Appl. Toxicol., 1985, 5, 1097-1103)

Statistics:

-ANOVA and Tukey's studentized range test: Serum chemistry and counts of testicular spermatids, epididymal sperm
-Duncan's multiple range test: Hematology, body weights, organ weights

Clinical signs:

no effects observed

Mortality:

no mortality observed

Body weight and weight changes:

effects observed, treatment-related

Food consumption and compound intake (if feeding study):

not examined

Food efficiency:

not examined

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

not examined

Ophthalmological findings:

not examined

Haematological findings:

effects observed, treatment-related

Clinical biochemistry findings:

effects observed, treatment-related

Urinalysis findings:

not examined

Behaviour (functional findings):

not examined

Organ weight findings including organ / body weight ratios:

effects observed, treatment-related

Gross pathological findings:

effects observed, treatment-related

Histopathological findings: non-neoplastic:

effects observed, treatment-related

Histopathological findings: neoplastic:

no effects observed

Details on results:

CLINICAL SIGNS AND MORTALITY
No mortality was observed, nor changes in any clinical signs.

BODY WEIGHT AND WEIGHT GAIN
Exposed males tended to have greater weight gain in the initial half of the study, compared to the controls. However, this was only statistically significant in weeks 6-14 for the mid-dose (3300 ppm) group compared to untreated controls. No similar trend was observed in females.

HAEMATOLOGY
Only a few parameters were statistically different, and only in one control group but not both; no observed changes were considered biologically relevant. See Table 1 for results.

CLINICAL CHEMISTRY
Only a few parameters were statistically different, and only in one control group but not both; no observed changes were considered biologically relevant. However, statistically significant elevation in comparison to both control groups was seen in the high-dose (7100 ppm) male group (this group also showed the largest liver weight increase). See Table 1 for results.

ORGAN WEIGHTS
Significant liver-weight increase was observed in both male and female animals (39% and 18% respectivels) at the high-dose (7100 ppm). At the middle-dose (3300 ppm) only the increase in males (26%) was significant compared to both controls; the increase observed in females (6%) was only significant compared to sham-exposed animals.
Significant kidney-weight increase was observed in males at the high- (7100 ppm) and mid-dose (3300 ppm). The increase observed in females at the high-dose (7100 ppm) was only significant compared to sham-exposed animals.
Weight increase tended to be concentration related.

GROSS PATHOLOGY
No gross pathological changes associated with exposure to diisopropyl ether were observed.

HISTOPATHOLOGY: NON-NEOPLASTIC
Mild hypertrophy was observed in liver cells from central to mid-zonal areas for the male high-dose (7100 ppm) group. Similar changes in morphology were not observed in females, or either sex at the mid-dose (3300 ppm). It was suggested that hypertrophy was not visible with light microscopy until bulk-tissue weight changes were greater than ~30%.
In the kidney there was a mild increase in hyaline droplets observed in the proximal convoluted tubles of males in the high-dose (7100 ppm) group. No similar changes were observed in any other group.
No other histopathological changes were observed in other tissues.

HISTORICAL CONTROL DATA
Percentage of abnormal sperm: 2.8-5.6%

OTHER FINDINGS
The numbers of sperm and spermatids were not changed by exposure to diisopropyl ether compared to the control groups.
At the high-dose (7100 ppm), the number (5.3%) of abnormal sperm (altered head morphology or broken) was significantly increased compared to the control groups (2.8%). However, no specific abnormality was predominant, and the result was not considered biologically significant.

Dose descriptor:

NOAEC

Effect level:

3 300 ppm

Sex:

male/female

Basis for effect level:

other: Effect concentration identified by registrant (minor changes in liver and kidney weights without discernible morphological effects at 3300 ppm; at 7100 ppm, these increased weights were accompanied by small morphologic changes).

Dose descriptor:

NOEC

Effect level:

480 ppm

Sex:

male/female

Basis for effect level:

other: See above remark

Critical effects observed:

not specified

Table 1. Mean parameters ( ±SD) of hematology and serum chemistry that had significant differences between exposed and control groups following subchronic exposures.

Parameters	Untreated controls	Sham-exposed	480 ppm DIPE	3300 ppm DIPE	7100 ppm DIPE
Males
Creatinine (mg/dL)	0.61 ± 0.06	0.64 ± 0.04	0.64 ± 0.04	0.67 ± 0.06	0.69 ± 0.03^b
Cholesterol (mg/dL)	71 ± 10	74 ± 13	77 ± 17	77 ± 9	95 ± 22^d
SDH (IU/L)	11 ± 5	16 ± 7	13 ± 6	9 ± 3^c	9 ± 3^c
Lymphocytes^a	92 ± 3	92 ± 4	90 ± 6	90 ± 4	87 ± 6^b
Monocytes^a	1 ± 2	1 ± 2	2 ± 2	2 ± 2	3 ± 2^b
Females
Potassium (mmol/L)	4.96 ± 0.35	4.68 ± 0.24	4.58 ± 0.41	4.51 ± 0.37^b	4.45 ± 0.40^b
Lymphocytes^a	92 ± 3	88 ± 5	86 ± 6^b	85 ± 7^b	86 ± 3^b

^apercent of total white blood cells.

^bSignificantly different from untreated controls.

^cSignificantly different from sham-exposed controls.

^dSignificantly different from both control groups.

Conclusions:

Subchronic exposure to 3300 ppm diisopropyl ether lead to only minor weight changes in liver and kidneys. Subchronic exposure to 7100 ppm diisopropyl ether lead to increased weight changes, accompanied by small morphological changes. Diisopropyl ether demonstrated relatively low toxicity for the endpoints evaluated. Therefore, the NOAEC was set to 3300 ppm and the NOEC to 480 ppm.

Executive summary:

Read across from diisopropylether (DIPE) is justified on the basis that NOAECs reported for the constituents of this UVCB range from 3500 mg/m³ for hexanol to 31680 mg/m³ for propylene dimers, which can be considered indicative of low toxicity for this UVCB substance. DIPE comprises approximately 50% of the UVCB substance and is, therefore, the main constituent. The C6 alkanes/alkenes are, with 20%, the second largest constituent. The NOAECs of both DIPE and C6 alkanes/alkenes, together accounting for approximately 70% of the UVCB substance, are in the same order of magnitude (3300 ppm and 3000 ppm, respectively).

Mild hypertrophy was observed at the high-dose in combination with 39% (male) and 18% (female) increased absolute liver weight. The high dose of 7100 ppm was considered to be the LOAEC effect level.

At the mid-dose, no histopathological changes were observed. Absolute liver weight gain was 26% in males only; 6% in females. Sorbitol dehydrogenase dropped from 11(5) or 16(7) IU/L in controls to 9(3) IU/L. The absolute liver weight gain seen only in males, and unaccompanied by other effects, is considered to be a suitable NOAEC.

Based on "adverse liver effects" criteria by TERA (Toxicology Excellence for Risk Assessment): presence of histopathology (moderate hypertrophy) in combination with statistically significant absolute or relative weight changes; or liver weight change >10%; or doubling of serum levels of liver enzyme activity.

Reference 2

Endpoint:

sub-chronic toxicity: inhalation

Type of information:

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

Adequacy of study:

key study

Study period:

1996

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

guideline study with acceptable restrictions

Justification for type of information:

REPORTING FORMAT FOR THE ANALOGUE APPROACH

The test item has the main constituent of isopropyl ether (approximately 50%). Minor constituents comprise propylene dimers (approximately 20% C6 hydrocarbons, mainly C6 alkenes), propylene trimers (approximately 10% C9 hydrocarbons), hexanols (approximately 10%) and C3 alcohols (approximately 10% consisting of both isopropanol and n-propanol). Read across from diisopropylether (DIPE) and other constituents is justified on the basis that NOAECs reported for the constituents of this UVCB range from 3500 mg/m3 for hexanol to 31680 mg/m3 for propylene dimers, which can be considered indicative of low toxicity for this UVCB substance. DIPE comprises approximately 50% of the UVCB substance and is, therefore, the main constituent.

Reason / purpose for cross-reference:

reference to same study

Reason / purpose for cross-reference:

read-across source

Qualifier:

equivalent or similar to guideline

Guideline:

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

Deviations:

yes

Remarks:

-Some observations/parameters were not reported for certain organs; food and water consumption not reported

GLP compliance:

no

Limit test:

no

Species:

rat

Strain:

other: Sprague-Dawley-derived rats [Tac:N(SD)fBR]

Sex:

male/female

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Source: Single shipment from Taconic Farms, German-town, N.Y.
- Age at study initiation: approximately 8 weeks
- Housing: Individually housed in 1-cubic meter (H-1000) inhalation chambers; untreated control animals were housed in a separate animal room in the same caging.
- Diet: ad libitum, except during exposure; certified Purina rodent chow 5002
- Water: ad libitum, except during exposure
- Acclimation period: 2 weeks


ENVIRONMENTAL CONDITIONS
- Temperature (°C): 20-22 °C
- Humidity (%): 40-60%
- Photoperiod (hrs dark / hrs light): 12h/12h

Route of administration:

inhalation: vapour

Type of inhalation exposure:

whole body

Vehicle:

other: unchanged (no vehicle)

Remarks on MMAD:

MMAD / GSD: Not applicable

Details on inhalation exposure:

GENERATION OF TEST ATMOSPHERE / CHAMBER DESCRIPTION
- Exposure apparatus: three 1 cubic meter, H1000 exposure chambers
- Source and rate of air: Filtered room air combined with air stream containing diisopropyl ether generate by evaporation from a heated (46 °C) wick. The wick surrounded a stainless steel tube and the wick and tube were enclosed in a 5.08 cm glass pipe through which HEPA-filtered room air flowed at approximately 290 Ipm.
- Temperature, humidity, pressure in air chamber: 23-24 °C, 60-67%, monitored every 30 min
- Air change rate: at least 12 per hour
- Treatment of exhaust air: filtered through charcoal beds

TEST ATMOSPHERE
- Brief description of analytical method used: 50-250 µL samples injected directly to a Hewlett-Packard 5880A gas chromatograph (GC) with flame ionization detector (FID) and fused silica column (30 m, 0.53 mm ID, 1 µm film). The helium carrier flow was 5 mL/min with 27 mL/min makeup air; oven temperature at 40 °C for 10 mininutes followed by a ramp at 4 °C/min to 200 °C. The GC calibration was done with known volumes vapourised in 500 mL glass sampling flask. In addition, periodic samples were taken and analysed by GC/ mass spectroscopy (MS) with mass spectrum scanned from 35 to 200 amu.

Analytical verification of doses or concentrations:

yes

Details on analytical verification of doses or concentrations:

480 ppm: 2000 ±200 mg/cubic meter, 480±48 ppm; Total hydrocarbons: 2100 ±200 mg/cubic meter (95 ±4 weight% diisopropyl ether)
3300 ppm: 13800 ±900 mg/cubic meter, 3300±215 ppm; Total hydrocarbons: 14900 ±1100 mg/cubic meter (92 ±2 weight% diisopropyl ether)
7100 ppm: 29700 ±1600 mg/cubic meter, 7100±383 ppm; Total hydrocarbons: 32600 ±2000 mg/cubic meter (91 ±2 weight% diisopropyl ether)

In GC/MS analysis the sample comprised approximately 86-87% diisopropyl ether, with the remaining 13-14% comprising of more than 20 alkanes, alkenes, cycloalkanes, ketones, alcohols in the range C3-C9; a trace amount of toluene was also present.

Duration of treatment / exposure:

13 weeks

Frequency of treatment:

6-hour exposure per day, 5 exposure days per week

Remarks:

Doses / Concentrations:
480 ppm (2000 mg/cubic meter)
Basis:
nominal conc.

Remarks:

Doses / Concentrations:
3300 ppm (13800 mg/cubic meter)
Basis:
nominal conc.

Remarks:

Doses / Concentrations:
7100 ppm (29700 mg/cubic meter)
Basis:
nominal conc.

No. of animals per sex per dose:

14 animals per sex per dose

Control animals:

yes, concurrent no treatment

yes, sham-exposed

Details on study design:

- Dose selection rationale: Review of available literature data on toxicity. Due to safety considerations, the upper dose was selected to be approximately half the lower explosive limit of the substance.
- Untreated control remained in a separate animal room. Apart from routine animal care, body weights and clinical observations, they were not handled.
- Sham control were treated the same as the diisopropyl ether group except actual exposure.

Positive control:

No positive control was used.

Observations and examinations performed and frequency:

CAGE SIDE OBSERVATIONS: Yes
- Time schedule: daily except weekends

DETAILED CLINICAL OBSERVATIONS: Yes
- Time schedule: daily except weekends

BODY WEIGHT: Yes
- Time schedule for examinations: weekly

FOOD CONSUMPTION: No

FOOD EFFICIENCY: No

WATER CONSUMPTION: No

OPHTHALMOSCOPIC EXAMINATION: No

HAEMATOLOGY: Yes
- Time schedule for collection of blood: at sacrifice
- Anaesthetic used for blood collection: yes; light ether
- Animals fasted: yes; after last exposure, fasted overnight before sampling
- How many animals: all
- Parameters checked: white blood cell (WBC), red blood cell (RBC), hemoglobin (Hb), hematocrit (Hct), mean corpuscular volume (MCV), mean corpuscular hemoglobin (MCH), mean corpuscular hemoglobin concentration (MCHC), platelets, and differential cell count.

CLINICAL CHEMISTRY: Yes
- Time schedule for collection of blood: at sacrifice
- Animals fasted: yes; after last exposure, fasted overnight before sampling
- How many animals: all
- Parameters checked: glucose, urea nitrogen, total protein, globulin (G), albumin (A), A:G ratio, sorbital dehydrogenase, aspartate aminotransferase, alanine aminotransferase, alkaline phosphatase, creatinine, cholesterol, total bilirubin, triglycerides, uric acid, potassium (K), sodium (Na), chloride (Cl), calcium (Ca), and phosphorus (P) using Hitachi blood analyser 704.

URINALYSIS: No

NEUROBEHAVIOURAL EXAMINATION: No

Sacrifice and pathology:

The animals were sacrificed over several days during the 14th week. Exposures and control animals were continued during this period.
GROSS PATHOLOGY: Yes
The following organs were examined and weighed when present: adrenals, kidney, spleen, brain, liver, testes, epididymides, ovaris, thymus, heart, prostate, and uterus. In addition, the weight of the right middle lung lobe was measured after drying at 90 °C.

HISTOPATHOLOGY: Yes
The following tissues, from sham and high dose groups, were examined and preserved in buffered 10% formalin: adrenals ovaries, sternum, pancreas, brain (three sections), salivary gland, eye, optic nerce, spleen, heart, stomach, colon, testes, duodenum, thymus, kidneys, thyroid, liver, lymph nodes (tracheobronchial, anterior mediastinal, cervical), lung (left lobe), nasal turbinates, thigh muscle, skin (six sites), urinary bladder, sciatic nerve, seminal vesicals, preputial glands, and gross lesions.
The following tissues, from untreated and remaining groups, were examined and preserved in buffered 10% formalin: lungs, tracheobronchial lymph nodes, and gross lesions.
Finally, the male 14600 mg/cubic meter group also had slides prepared for liver and kidneys.

Other examinations:

Testis and associated tissues were preserved in 10% formalin for all groups.
From the two control groups and the high dose group, 10 animals were selected and the left cauda epididymis examined for sperm morphology and number. The left testis was used for weight and spermatid number.
Methodology: morphology (Wyrobek, A.J., Mutat. Res., 1983, 115, 1-72), number of sperm and spermatids (Blazak, W.F., Fundam. Appl. Toxicol., 1985, 5, 1097-1103)

Statistics:

-ANOVA and Tukey's studentized range test: Serum chemistry and counts of testicular spermatids, epididymal sperm
-Duncan's multiple range test: Hematology, body weights, organ weights

Clinical signs:

no effects observed

Mortality:

no mortality observed

Body weight and weight changes:

effects observed, treatment-related

Food consumption and compound intake (if feeding study):

not examined

Food efficiency:

not examined

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

not examined

Ophthalmological findings:

not examined

Haematological findings:

effects observed, treatment-related

Clinical biochemistry findings:

effects observed, treatment-related

Urinalysis findings:

not examined

Behaviour (functional findings):

not examined

Organ weight findings including organ / body weight ratios:

effects observed, treatment-related

Gross pathological findings:

effects observed, treatment-related

Histopathological findings: non-neoplastic:

effects observed, treatment-related

Histopathological findings: neoplastic:

no effects observed

Details on results:

CLINICAL SIGNS AND MORTALITY
No mortality was observed, nor changes in any clinical signs.

BODY WEIGHT AND WEIGHT GAIN
Exposed males tended to have greater weight gain in the initial half of the study, compared to the controls. However, this was only statistically significant in weeks 6-14 for the mid-dose (3300 ppm) group compared to untreated controls. No similar trend was observed in females.

HAEMATOLOGY
Only a few parameters were statistically different, and only in one control group but not both; no observed changes were considered biologically relevant. See Table 1 for results.

CLINICAL CHEMISTRY
Only a few parameters were statistically different, and only in one control group but not both; no observed changes were considered biologically relevant. However, statistically significant elevation in comparison to both control groups was seen in the high-dose (7100 ppm) male group (this group also showed the largest liver weight increase). See Table 1 for results.

ORGAN WEIGHTS
Significant liver-weight increase was observed in both male and female animals (39% and 18% respectivels) at the high-dose (7100 ppm). At the middle-dose (3300 ppm) only the increase in males (26%) was significant compared to both controls; the increase observed in females (6%) was only significant compared to sham-exposed animals.
Significant kidney-weight increase was observed in males at the high- (7100 ppm) and mid-dose (3300 ppm). The increase observed in females at the high-dose (7100 ppm) was only significant compared to sham-exposed animals.
Weight increase tended to be concentration related.

GROSS PATHOLOGY
No gross pathological changes associated with exposure to diisopropyl ether were observed.

HISTOPATHOLOGY: NON-NEOPLASTIC
Mild hypertrophy was observed in liver cells from central to mid-zonal areas for the male high-dose (7100 ppm) group. Similar changes in morphology were not observed in females, or either sex at the mid-dose (3300 ppm). It was suggested that hypertrophy was not visible with light microscopy until bulk-tissue weight changes were greater than ~30%.
In the kidney there was a mild increase in hyaline droplets observed in the proximal convoluted tubles of males in the high-dose (7100 ppm) group. No similar changes were observed in any other group.
No other histopathological changes were observed in other tissues.

HISTORICAL CONTROL DATA
Percentage of abnormal sperm: 2.8-5.6%

OTHER FINDINGS
The numbers of sperm and spermatids were not changed by exposure to diisopropyl ether compared to the control groups.
At the high-dose (7100 ppm), the number (5.3%) of abnormal sperm (altered head morphology or broken) was significantly increased compared to the control groups (2.8%). However, no specific abnormality was predominant, and the result was not considered biologically significant.

Dose descriptor:

NOAEC

Effect level:

3 300 ppm

Sex:

male/female

Basis for effect level:

other: Effect concentration identified by registrant (minor changes in liver and kidney weights without discernible morphological effects at 3300 ppm; at 7100 ppm, these increased weights were accompanied by small morphologic changes).

Dose descriptor:

NOEC

Effect level:

480 ppm

Sex:

male/female

Basis for effect level:

other: See above remark

Critical effects observed:

not specified

Table 1. Mean parameters ( ±SD) of hematology and serum chemistry that had significant differences between exposed and control groups following subchronic exposures.

Parameters	Untreated controls	Sham-exposed	480 ppm DIPE	3300 ppm DIPE	7100 ppm DIPE
Males
Creatinine (mg/dL)	0.61 ± 0.06	0.64 ± 0.04	0.64 ± 0.04	0.67 ± 0.06	0.69 ± 0.03^b
Cholesterol (mg/dL)	71 ± 10	74 ± 13	77 ± 17	77 ± 9	95 ± 22^d
SDH (IU/L)	11 ± 5	16 ± 7	13 ± 6	9 ± 3^c	9 ± 3^c
Lymphocytes^a	92 ± 3	92 ± 4	90 ± 6	90 ± 4	87 ± 6^b
Monocytes^a	1 ± 2	1 ± 2	2 ± 2	2 ± 2	3 ± 2^b
Females
Potassium (mmol/L)	4.96 ± 0.35	4.68 ± 0.24	4.58 ± 0.41	4.51 ± 0.37^b	4.45 ± 0.40^b
Lymphocytes^a	92 ± 3	88 ± 5	86 ± 6^b	85 ± 7^b	86 ± 3^b

^apercent of total white blood cells.

^bSignificantly different from untreated controls.

^cSignificantly different from sham-exposed controls.

^dSignificantly different from both control groups.

Conclusions:

Subchronic exposure to 3300 ppm diisopropyl ether lead to only minor weight changes in liver and kidneys. Subchronic exposure to 7100 ppm diisopropyl ether lead to increased weight changes, accompanied by small morphological changes. Diisopropyl ether demonstrated relatively low toxicity for the endpoints evaluated. Therefore, the NOAEC was set to 3300 ppm and the NOEC to 480 ppm.

Executive summary:

Read across from diisopropylether (DIPE) is justified on the basis that NOAECs reported for the constituents of this UVCB range from 3500 mg/m³ for hexanol to 31680 mg/m³ for propylene dimers, which can be considered indicative of low toxicity for this UVCB substance. DIPE comprises approximately 50% of the UVCB substance and is, therefore, the main constituent. The C6 alkanes/alkenes are, with 20%, the second largest constituent. The NOAECs of both DIPE and C6 alkanes/alkenes, together accounting for approximately 70% of the UVCB substance, are in the same order of magnitude (3300 ppm and 3000 ppm, respectively).

Mild hypertrophy was observed at the high-dose in combination with 39% (male) and 18% (female) increased absolute liver weight. The high dose of 7100 ppm was considered to be the LOAEC effect level.

At the mid-dose, no histopathological changes were observed. Absolute liver weight gain was 26% in males only; 6% in females. Sorbitol dehydrogenase dropped from 11(5) or 16(7) IU/L in controls to 9(3) IU/L. The absolute liver weight gain seen only in males, and unaccompanied by other effects, is considered to be a suitable NOAEC.

Based on "adverse liver effects" criteria by TERA (Toxicology Excellence for Risk Assessment): presence of histopathology (moderate hypertrophy) in combination with statistically significant absolute or relative weight changes; or liver weight change >10%; or doubling of serum levels of liver enzyme activity.

Endpoint conclusion

Endpoint conclusion:

adverse effect observed

Dose descriptor:

NOAEC

13 800 mg/m³

Study duration:

subchronic

Experimental exposure time per week (hours/week):

30

Species:

rat

Quality of whole database:

The information for this endpoint was taken from a well-constructed 90-day inhalation toxicity study in rats with DIPE at exposure levels of 0 (controls), 480, 3300 and 7100 ppm (equivalent to 0, 2000, 13800 and 29700 mg/m3). The study was controlled with a group of rats receiving air only and also a sham-exposed group. For the read-across substance, DIPE, the presence of hepatotoxicity and renal toxicity was detected in males and, to a reduced extent, females at both the high dose level of 7100 ppm and the intermediate dose level of 3300 ppm. The NOAEC for systemic toxicity was considered to be the intermediate dose level tested of 3300 ppm (equivalent to 13800 mg/m3).

Repeated dose toxicity: inhalation - local effects

Link to relevant study records

Reference

Reference 1

Endpoint:

sub-chronic toxicity: inhalation

Type of information:

experimental study

Adequacy of study:

key study

Study period:

1996

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

guideline study with acceptable restrictions

Reason / purpose for cross-reference:

reference to same study

Qualifier:

equivalent or similar to guideline

Guideline:

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

Deviations:

yes

Remarks:

-Some observations/parameters were not reported for certain organs; food and water consumption not reported

GLP compliance:

no

Limit test:

no

Species:

rat

Strain:

other: Sprague-Dawley-derived rats [Tac:N(SD)fBR]

Sex:

male/female

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Source: Single shipment from Taconic Farms, German-town, N.Y.
- Age at study initiation: approximately 8 weeks
- Housing: Individually housed in 1-cubic meter (H-1000) inhalation chambers; untreated control animals were housed in a separate animal room in the same caging.
- Diet: ad libitum, except during exposure; certified Purina rodent chow 5002
- Water: ad libitum, except during exposure
- Acclimation period: 2 weeks


ENVIRONMENTAL CONDITIONS
- Temperature (°C): 20-22 °C
- Humidity (%): 40-60%
- Photoperiod (hrs dark / hrs light): 12h/12h

Route of administration:

inhalation: vapour

Type of inhalation exposure:

whole body

Vehicle:

other: unchanged (no vehicle)

Remarks on MMAD:

MMAD / GSD: Not applicable

Details on inhalation exposure:

GENERATION OF TEST ATMOSPHERE / CHAMBER DESCRIPTION
- Exposure apparatus: three 1 cubic meter, H1000 exposure chambers
- Source and rate of air: Filtered room air combined with air stream containing diisopropyl ether generate by evaporation from a heated (46 °C) wick. The wick surrounded a stainless steel tube and the wick and tube were enclosed in a 5.08 cm glass pipe through which HEPA-filtered room air flowed at approximately 290 Ipm.
- Temperature, humidity, pressure in air chamber: 23-24 °C, 60-67%, monitored every 30 min
- Air change rate: at least 12 per hour
- Treatment of exhaust air: filtered through charcoal beds

TEST ATMOSPHERE
- Brief description of analytical method used: 50-250 µL samples injected directly to a Hewlett-Packard 5880A gas chromatograph (GC) with flame ionization detector (FID) and fused silica column (30 m, 0.53 mm ID, 1 µm film). The helium carrier flow was 5 mL/min with 27 mL/min makeup air; oven temperature at 40 °C for 10 mininutes followed by a ramp at 4 °C/min to 200 °C. The GC calibration was done with known volumes vapourised in 500 mL glass sampling flask. In addition, periodic samples were taken and analysed by GC/ mass spectroscopy (MS) with mass spectrum scanned from 35 to 200 amu.

Analytical verification of doses or concentrations:

yes

Details on analytical verification of doses or concentrations:

480 ppm: 2000 ±200 mg/cubic meter, 480±48 ppm; Total hydrocarbons: 2100 ±200 mg/cubic meter (95 ±4 weight% diisopropyl ether)
3300 ppm: 13800 ±900 mg/cubic meter, 3300±215 ppm; Total hydrocarbons: 14900 ±1100 mg/cubic meter (92 ±2 weight% diisopropyl ether)
7100 ppm: 29700 ±1600 mg/cubic meter, 7100±383 ppm; Total hydrocarbons: 32600 ±2000 mg/cubic meter (91 ±2 weight% diisopropyl ether)

In GC/MS analysis the sample comprised approximately 86-87% diisopropyl ether, with the remaining 13-14% comprising of more than 20 alkanes, alkenes, cycloalkanes, ketones, alcohols in the range C3-C9; a trace amount of toluene was also present.

Duration of treatment / exposure:

13 weeks

Frequency of treatment:

6-hour exposure per day, 5 exposure days per week

Remarks:

Doses / Concentrations:
480 ppm (2000 mg/cubic meter)
Basis:
nominal conc.

Remarks:

Doses / Concentrations:
3300 ppm (13800 mg/cubic meter)
Basis:
nominal conc.

Remarks:

Doses / Concentrations:
7100 ppm (29700 mg/cubic meter)
Basis:
nominal conc.

No. of animals per sex per dose:

14 animals per sex per dose

Control animals:

yes, concurrent no treatment

yes, sham-exposed

Details on study design:

- Dose selection rationale: Review of available literature data on toxicity. Due to safety considerations, the upper dose was selected to be approximately half the lower explosive limit of the substance.
- Untreated control remained in a separate animal room. Apart from routine animal care, body weights and clinical observations, they were not handled.
- Sham control were treated the same as the diisopropyl ether group except actual exposure.

Positive control:

No positive control was used.

Observations and examinations performed and frequency:

CAGE SIDE OBSERVATIONS: Yes
- Time schedule: daily except weekends

DETAILED CLINICAL OBSERVATIONS: Yes
- Time schedule: daily except weekends

BODY WEIGHT: Yes
- Time schedule for examinations: weekly

FOOD CONSUMPTION: No

FOOD EFFICIENCY: No

WATER CONSUMPTION: No

OPHTHALMOSCOPIC EXAMINATION: No

HAEMATOLOGY: Yes
- Time schedule for collection of blood: at sacrifice
- Anaesthetic used for blood collection: yes; light ether
- Animals fasted: yes; after last exposure, fasted overnight before sampling
- How many animals: all
- Parameters checked: white blood cell (WBC), red blood cell (RBC), hemoglobin (Hb), hematocrit (Hct), mean corpuscular volume (MCV), mean corpuscular hemoglobin (MCH), mean corpuscular hemoglobin concentration (MCHC), platelets, and differential cell count.

CLINICAL CHEMISTRY: Yes
- Time schedule for collection of blood: at sacrifice
- Animals fasted: yes; after last exposure, fasted overnight before sampling
- How many animals: all
- Parameters checked: glucose, urea nitrogen, total protein, globulin (G), albumin (A), A:G ratio, sorbital dehydrogenase, aspartate aminotransferase, alanine aminotransferase, alkaline phosphatase, creatinine, cholesterol, total bilirubin, triglycerides, uric acid, potassium (K), sodium (Na), chloride (Cl), calcium (Ca), and phosphorus (P) using Hitachi blood analyser 704.

URINALYSIS: No

NEUROBEHAVIOURAL EXAMINATION: No

Sacrifice and pathology:

The animals were sacrificed over several days during the 14th week. Exposures and control animals were continued during this period.
GROSS PATHOLOGY: Yes
The following organs were examined and weighed when present: adrenals, kidney, spleen, brain, liver, testes, epididymides, ovaris, thymus, heart, prostate, and uterus. In addition, the weight of the right middle lung lobe was measured after drying at 90 °C.

HISTOPATHOLOGY: Yes
The following tissues, from sham and high dose groups, were examined and preserved in buffered 10% formalin: adrenals ovaries, sternum, pancreas, brain (three sections), salivary gland, eye, optic nerce, spleen, heart, stomach, colon, testes, duodenum, thymus, kidneys, thyroid, liver, lymph nodes (tracheobronchial, anterior mediastinal, cervical), lung (left lobe), nasal turbinates, thigh muscle, skin (six sites), urinary bladder, sciatic nerve, seminal vesicals, preputial glands, and gross lesions.
The following tissues, from untreated and remaining groups, were examined and preserved in buffered 10% formalin: lungs, tracheobronchial lymph nodes, and gross lesions.
Finally, the male 14600 mg/cubic meter group also had slides prepared for liver and kidneys.

Other examinations:

Testis and associated tissues were preserved in 10% formalin for all groups.
From the two control groups and the high dose group, 10 animals were selected and the left cauda epididymis examined for sperm morphology and number. The left testis was used for weight and spermatid number.
Methodology: morphology (Wyrobek, A.J., Mutat. Res., 1983, 115, 1-72), number of sperm and spermatids (Blazak, W.F., Fundam. Appl. Toxicol., 1985, 5, 1097-1103)

Statistics:

-ANOVA and Tukey's studentized range test: Serum chemistry and counts of testicular spermatids, epididymal sperm
-Duncan's multiple range test: Hematology, body weights, organ weights

Clinical signs:

no effects observed

Mortality:

no mortality observed

Body weight and weight changes:

effects observed, treatment-related

Food consumption and compound intake (if feeding study):

not examined

Food efficiency:

not examined

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

not examined

Ophthalmological findings:

not examined

Haematological findings:

effects observed, treatment-related

Clinical biochemistry findings:

effects observed, treatment-related

Urinalysis findings:

not examined

Behaviour (functional findings):

not examined

Organ weight findings including organ / body weight ratios:

effects observed, treatment-related

Gross pathological findings:

effects observed, treatment-related

Histopathological findings: non-neoplastic:

effects observed, treatment-related

Histopathological findings: neoplastic:

no effects observed

Details on results:

CLINICAL SIGNS AND MORTALITY
No mortality was observed, nor changes in any clinical signs.

BODY WEIGHT AND WEIGHT GAIN
Exposed males tended to have greater weight gain in the initial half of the study, compared to the controls. However, this was only statistically significant in weeks 6-14 for the mid-dose (3300 ppm) group compared to untreated controls. No similar trend was observed in females.

HAEMATOLOGY
Only a few parameters were statistically different, and only in one control group but not both; no observed changes were considered biologically relevant. See Table 1 for results.

CLINICAL CHEMISTRY
Only a few parameters were statistically different, and only in one control group but not both; no observed changes were considered biologically relevant. However, statistically significant elevation in comparison to both control groups was seen in the high-dose (7100 ppm) male group (this group also showed the largest liver weight increase). See Table 1 for results.

ORGAN WEIGHTS
Significant liver-weight increase was observed in both male and female animals (39% and 18% respectivels) at the high-dose (7100 ppm). At the middle-dose (3300 ppm) only the increase in males (26%) was significant compared to both controls; the increase observed in females (6%) was only significant compared to sham-exposed animals.
Significant kidney-weight increase was observed in males at the high- (7100 ppm) and mid-dose (3300 ppm). The increase observed in females at the high-dose (7100 ppm) was only significant compared to sham-exposed animals.
Weight increase tended to be concentration related.

GROSS PATHOLOGY
No gross pathological changes associated with exposure to diisopropyl ether were observed.

HISTOPATHOLOGY: NON-NEOPLASTIC
Mild hypertrophy was observed in liver cells from central to mid-zonal areas for the male high-dose (7100 ppm) group. Similar changes in morphology were not observed in females, or either sex at the mid-dose (3300 ppm). It was suggested that hypertrophy was not visible with light microscopy until bulk-tissue weight changes were greater than ~30%.
In the kidney there was a mild increase in hyaline droplets observed in the proximal convoluted tubles of males in the high-dose (7100 ppm) group. No similar changes were observed in any other group.
No other histopathological changes were observed in other tissues.

HISTORICAL CONTROL DATA
Percentage of abnormal sperm: 2.8-5.6%

OTHER FINDINGS
The numbers of sperm and spermatids were not changed by exposure to diisopropyl ether compared to the control groups.
At the high-dose (7100 ppm), the number (5.3%) of abnormal sperm (altered head morphology or broken) was significantly increased compared to the control groups (2.8%). However, no specific abnormality was predominant, and the result was not considered biologically significant.

Dose descriptor:

NOAEC

Effect level:

3 300 ppm

Sex:

male/female

Basis for effect level:

other: Effect concentration identified by registrant (minor changes in liver and kidney weights without discernible morphological effects at 3300 ppm; at 7100 ppm, these increased weights were accompanied by small morphologic changes).

Dose descriptor:

NOEC

Effect level:

480 ppm

Sex:

male/female

Basis for effect level:

other: See above remark

Critical effects observed:

not specified

Table 1. Mean parameters ( ±SD) of hematology and serum chemistry that had significant differences between exposed and control groups following subchronic exposures.

Parameters	Untreated controls	Sham-exposed	480 ppm DIPE	3300 ppm DIPE	7100 ppm DIPE
Males
Creatinine (mg/dL)	0.61 ± 0.06	0.64 ± 0.04	0.64 ± 0.04	0.67 ± 0.06	0.69 ± 0.03^b
Cholesterol (mg/dL)	71 ± 10	74 ± 13	77 ± 17	77 ± 9	95 ± 22^d
SDH (IU/L)	11 ± 5	16 ± 7	13 ± 6	9 ± 3^c	9 ± 3^c
Lymphocytes^a	92 ± 3	92 ± 4	90 ± 6	90 ± 4	87 ± 6^b
Monocytes^a	1 ± 2	1 ± 2	2 ± 2	2 ± 2	3 ± 2^b
Females
Potassium (mmol/L)	4.96 ± 0.35	4.68 ± 0.24	4.58 ± 0.41	4.51 ± 0.37^b	4.45 ± 0.40^b
Lymphocytes^a	92 ± 3	88 ± 5	86 ± 6^b	85 ± 7^b	86 ± 3^b

^apercent of total white blood cells.

^bSignificantly different from untreated controls.

^cSignificantly different from sham-exposed controls.

^dSignificantly different from both control groups.

Conclusions:

Subchronic exposure to 3300 ppm diisopropyl ether lead to only minor weight changes in liver and kidneys. Subchronic exposure to 7100 ppm diisopropyl ether lead to increased weight changes, accompanied by small morphological changes. Diisopropyl ether demonstrated relatively low toxicity for the endpoints evaluated. Therefore, the NOAEC was set to 3300 ppm and the NOEC to 480 ppm.

Executive summary:

Read across from diisopropylether (DIPE) is justified on the basis that NOAECs reported for the constituents of this UVCB range from 3500 mg/m³ for hexanol to 31680 mg/m³ for propylene dimers, which can be considered indicative of low toxicity for this UVCB substance. DIPE comprises approximately 50% of the UVCB substance and is, therefore, the main constituent. The C6 alkanes/alkenes are, with 20%, the second largest constituent. The NOAECs of both DIPE and C6 alkanes/alkenes, together accounting for approximately 70% of the UVCB substance, are in the same order of magnitude (3300 ppm and 3000 ppm, respectively).

Mild hypertrophy was observed at the high-dose in combination with 39% (male) and 18% (female) increased absolute liver weight. The high dose of 7100 ppm was considered to be the LOAEC effect level.

At the mid-dose, no histopathological changes were observed. Absolute liver weight gain was 26% in males only; 6% in females. Sorbitol dehydrogenase dropped from 11(5) or 16(7) IU/L in controls to 9(3) IU/L. The absolute liver weight gain seen only in males, and unaccompanied by other effects, is considered to be a suitable NOAEC.

Based on "adverse liver effects" criteria by TERA (Toxicology Excellence for Risk Assessment): presence of histopathology (moderate hypertrophy) in combination with statistically significant absolute or relative weight changes; or liver weight change >10%; or doubling of serum levels of liver enzyme activity.

Reference 2

Endpoint:

sub-chronic toxicity: inhalation

Type of information:

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

Adequacy of study:

key study

Study period:

1996

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

guideline study with acceptable restrictions

Justification for type of information:

REPORTING FORMAT FOR THE ANALOGUE APPROACH

The test item has the main constituent of isopropyl ether (approximately 50%). Minor constituents comprise propylene dimers (approximately 20% C6 hydrocarbons, mainly C6 alkenes), propylene trimers (approximately 10% C9 hydrocarbons), hexanols (approximately 10%) and C3 alcohols (approximately 10% consisting of both isopropanol and n-propanol). Read across from diisopropylether (DIPE) and other constituents is justified on the basis that NOAECs reported for the constituents of this UVCB range from 3500 mg/m3 for hexanol to 31680 mg/m3 for propylene dimers, which can be considered indicative of low toxicity for this UVCB substance. DIPE comprises approximately 50% of the UVCB substance and is, therefore, the main constituent.

Reason / purpose for cross-reference:

reference to same study

Reason / purpose for cross-reference:

read-across source

Qualifier:

equivalent or similar to guideline

Guideline:

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

Deviations:

yes

Remarks:

-Some observations/parameters were not reported for certain organs; food and water consumption not reported

GLP compliance:

no

Limit test:

no

Species:

rat

Strain:

other: Sprague-Dawley-derived rats [Tac:N(SD)fBR]

Sex:

male/female

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Source: Single shipment from Taconic Farms, German-town, N.Y.
- Age at study initiation: approximately 8 weeks
- Housing: Individually housed in 1-cubic meter (H-1000) inhalation chambers; untreated control animals were housed in a separate animal room in the same caging.
- Diet: ad libitum, except during exposure; certified Purina rodent chow 5002
- Water: ad libitum, except during exposure
- Acclimation period: 2 weeks


ENVIRONMENTAL CONDITIONS
- Temperature (°C): 20-22 °C
- Humidity (%): 40-60%
- Photoperiod (hrs dark / hrs light): 12h/12h

Route of administration:

inhalation: vapour

Type of inhalation exposure:

whole body

Vehicle:

other: unchanged (no vehicle)

Remarks on MMAD:

MMAD / GSD: Not applicable

Details on inhalation exposure:

GENERATION OF TEST ATMOSPHERE / CHAMBER DESCRIPTION
- Exposure apparatus: three 1 cubic meter, H1000 exposure chambers
- Source and rate of air: Filtered room air combined with air stream containing diisopropyl ether generate by evaporation from a heated (46 °C) wick. The wick surrounded a stainless steel tube and the wick and tube were enclosed in a 5.08 cm glass pipe through which HEPA-filtered room air flowed at approximately 290 Ipm.
- Temperature, humidity, pressure in air chamber: 23-24 °C, 60-67%, monitored every 30 min
- Air change rate: at least 12 per hour
- Treatment of exhaust air: filtered through charcoal beds

TEST ATMOSPHERE
- Brief description of analytical method used: 50-250 µL samples injected directly to a Hewlett-Packard 5880A gas chromatograph (GC) with flame ionization detector (FID) and fused silica column (30 m, 0.53 mm ID, 1 µm film). The helium carrier flow was 5 mL/min with 27 mL/min makeup air; oven temperature at 40 °C for 10 mininutes followed by a ramp at 4 °C/min to 200 °C. The GC calibration was done with known volumes vapourised in 500 mL glass sampling flask. In addition, periodic samples were taken and analysed by GC/ mass spectroscopy (MS) with mass spectrum scanned from 35 to 200 amu.

Analytical verification of doses or concentrations:

yes

Details on analytical verification of doses or concentrations:

480 ppm: 2000 ±200 mg/cubic meter, 480±48 ppm; Total hydrocarbons: 2100 ±200 mg/cubic meter (95 ±4 weight% diisopropyl ether)
3300 ppm: 13800 ±900 mg/cubic meter, 3300±215 ppm; Total hydrocarbons: 14900 ±1100 mg/cubic meter (92 ±2 weight% diisopropyl ether)
7100 ppm: 29700 ±1600 mg/cubic meter, 7100±383 ppm; Total hydrocarbons: 32600 ±2000 mg/cubic meter (91 ±2 weight% diisopropyl ether)

In GC/MS analysis the sample comprised approximately 86-87% diisopropyl ether, with the remaining 13-14% comprising of more than 20 alkanes, alkenes, cycloalkanes, ketones, alcohols in the range C3-C9; a trace amount of toluene was also present.

Duration of treatment / exposure:

13 weeks

Frequency of treatment:

6-hour exposure per day, 5 exposure days per week

Remarks:

Doses / Concentrations:
480 ppm (2000 mg/cubic meter)
Basis:
nominal conc.

Remarks:

Doses / Concentrations:
3300 ppm (13800 mg/cubic meter)
Basis:
nominal conc.

Remarks:

Doses / Concentrations:
7100 ppm (29700 mg/cubic meter)
Basis:
nominal conc.

No. of animals per sex per dose:

14 animals per sex per dose

Control animals:

yes, concurrent no treatment

yes, sham-exposed

Details on study design:

- Dose selection rationale: Review of available literature data on toxicity. Due to safety considerations, the upper dose was selected to be approximately half the lower explosive limit of the substance.
- Untreated control remained in a separate animal room. Apart from routine animal care, body weights and clinical observations, they were not handled.
- Sham control were treated the same as the diisopropyl ether group except actual exposure.

Positive control:

No positive control was used.

Observations and examinations performed and frequency:

CAGE SIDE OBSERVATIONS: Yes
- Time schedule: daily except weekends

DETAILED CLINICAL OBSERVATIONS: Yes
- Time schedule: daily except weekends

BODY WEIGHT: Yes
- Time schedule for examinations: weekly

FOOD CONSUMPTION: No

FOOD EFFICIENCY: No

WATER CONSUMPTION: No

OPHTHALMOSCOPIC EXAMINATION: No

HAEMATOLOGY: Yes
- Time schedule for collection of blood: at sacrifice
- Anaesthetic used for blood collection: yes; light ether
- Animals fasted: yes; after last exposure, fasted overnight before sampling
- How many animals: all
- Parameters checked: white blood cell (WBC), red blood cell (RBC), hemoglobin (Hb), hematocrit (Hct), mean corpuscular volume (MCV), mean corpuscular hemoglobin (MCH), mean corpuscular hemoglobin concentration (MCHC), platelets, and differential cell count.

CLINICAL CHEMISTRY: Yes
- Time schedule for collection of blood: at sacrifice
- Animals fasted: yes; after last exposure, fasted overnight before sampling
- How many animals: all
- Parameters checked: glucose, urea nitrogen, total protein, globulin (G), albumin (A), A:G ratio, sorbital dehydrogenase, aspartate aminotransferase, alanine aminotransferase, alkaline phosphatase, creatinine, cholesterol, total bilirubin, triglycerides, uric acid, potassium (K), sodium (Na), chloride (Cl), calcium (Ca), and phosphorus (P) using Hitachi blood analyser 704.

URINALYSIS: No

NEUROBEHAVIOURAL EXAMINATION: No

Sacrifice and pathology:

The animals were sacrificed over several days during the 14th week. Exposures and control animals were continued during this period.
GROSS PATHOLOGY: Yes
The following organs were examined and weighed when present: adrenals, kidney, spleen, brain, liver, testes, epididymides, ovaris, thymus, heart, prostate, and uterus. In addition, the weight of the right middle lung lobe was measured after drying at 90 °C.

HISTOPATHOLOGY: Yes
The following tissues, from sham and high dose groups, were examined and preserved in buffered 10% formalin: adrenals ovaries, sternum, pancreas, brain (three sections), salivary gland, eye, optic nerce, spleen, heart, stomach, colon, testes, duodenum, thymus, kidneys, thyroid, liver, lymph nodes (tracheobronchial, anterior mediastinal, cervical), lung (left lobe), nasal turbinates, thigh muscle, skin (six sites), urinary bladder, sciatic nerve, seminal vesicals, preputial glands, and gross lesions.
The following tissues, from untreated and remaining groups, were examined and preserved in buffered 10% formalin: lungs, tracheobronchial lymph nodes, and gross lesions.
Finally, the male 14600 mg/cubic meter group also had slides prepared for liver and kidneys.

Other examinations:

Testis and associated tissues were preserved in 10% formalin for all groups.
From the two control groups and the high dose group, 10 animals were selected and the left cauda epididymis examined for sperm morphology and number. The left testis was used for weight and spermatid number.
Methodology: morphology (Wyrobek, A.J., Mutat. Res., 1983, 115, 1-72), number of sperm and spermatids (Blazak, W.F., Fundam. Appl. Toxicol., 1985, 5, 1097-1103)

Statistics:

-ANOVA and Tukey's studentized range test: Serum chemistry and counts of testicular spermatids, epididymal sperm
-Duncan's multiple range test: Hematology, body weights, organ weights

Clinical signs:

no effects observed

Mortality:

no mortality observed

Body weight and weight changes:

effects observed, treatment-related

Food consumption and compound intake (if feeding study):

not examined

Food efficiency:

not examined

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

not examined

Ophthalmological findings:

not examined

Haematological findings:

effects observed, treatment-related

Clinical biochemistry findings:

effects observed, treatment-related

Urinalysis findings:

not examined

Behaviour (functional findings):

not examined

Organ weight findings including organ / body weight ratios:

effects observed, treatment-related

Gross pathological findings:

effects observed, treatment-related

Histopathological findings: non-neoplastic:

effects observed, treatment-related

Histopathological findings: neoplastic:

no effects observed

Details on results:

CLINICAL SIGNS AND MORTALITY
No mortality was observed, nor changes in any clinical signs.

BODY WEIGHT AND WEIGHT GAIN
Exposed males tended to have greater weight gain in the initial half of the study, compared to the controls. However, this was only statistically significant in weeks 6-14 for the mid-dose (3300 ppm) group compared to untreated controls. No similar trend was observed in females.

HAEMATOLOGY
Only a few parameters were statistically different, and only in one control group but not both; no observed changes were considered biologically relevant. See Table 1 for results.

CLINICAL CHEMISTRY
Only a few parameters were statistically different, and only in one control group but not both; no observed changes were considered biologically relevant. However, statistically significant elevation in comparison to both control groups was seen in the high-dose (7100 ppm) male group (this group also showed the largest liver weight increase). See Table 1 for results.

ORGAN WEIGHTS
Significant liver-weight increase was observed in both male and female animals (39% and 18% respectivels) at the high-dose (7100 ppm). At the middle-dose (3300 ppm) only the increase in males (26%) was significant compared to both controls; the increase observed in females (6%) was only significant compared to sham-exposed animals.
Significant kidney-weight increase was observed in males at the high- (7100 ppm) and mid-dose (3300 ppm). The increase observed in females at the high-dose (7100 ppm) was only significant compared to sham-exposed animals.
Weight increase tended to be concentration related.

GROSS PATHOLOGY
No gross pathological changes associated with exposure to diisopropyl ether were observed.

HISTOPATHOLOGY: NON-NEOPLASTIC
Mild hypertrophy was observed in liver cells from central to mid-zonal areas for the male high-dose (7100 ppm) group. Similar changes in morphology were not observed in females, or either sex at the mid-dose (3300 ppm). It was suggested that hypertrophy was not visible with light microscopy until bulk-tissue weight changes were greater than ~30%.
In the kidney there was a mild increase in hyaline droplets observed in the proximal convoluted tubles of males in the high-dose (7100 ppm) group. No similar changes were observed in any other group.
No other histopathological changes were observed in other tissues.

HISTORICAL CONTROL DATA
Percentage of abnormal sperm: 2.8-5.6%

OTHER FINDINGS
The numbers of sperm and spermatids were not changed by exposure to diisopropyl ether compared to the control groups.
At the high-dose (7100 ppm), the number (5.3%) of abnormal sperm (altered head morphology or broken) was significantly increased compared to the control groups (2.8%). However, no specific abnormality was predominant, and the result was not considered biologically significant.

Dose descriptor:

NOAEC

Effect level:

3 300 ppm

Sex:

male/female

Basis for effect level:

other: Effect concentration identified by registrant (minor changes in liver and kidney weights without discernible morphological effects at 3300 ppm; at 7100 ppm, these increased weights were accompanied by small morphologic changes).

Dose descriptor:

NOEC

Effect level:

480 ppm

Sex:

male/female

Basis for effect level:

other: See above remark

Critical effects observed:

not specified

Table 1. Mean parameters ( ±SD) of hematology and serum chemistry that had significant differences between exposed and control groups following subchronic exposures.

Parameters	Untreated controls	Sham-exposed	480 ppm DIPE	3300 ppm DIPE	7100 ppm DIPE
Males
Creatinine (mg/dL)	0.61 ± 0.06	0.64 ± 0.04	0.64 ± 0.04	0.67 ± 0.06	0.69 ± 0.03^b
Cholesterol (mg/dL)	71 ± 10	74 ± 13	77 ± 17	77 ± 9	95 ± 22^d
SDH (IU/L)	11 ± 5	16 ± 7	13 ± 6	9 ± 3^c	9 ± 3^c
Lymphocytes^a	92 ± 3	92 ± 4	90 ± 6	90 ± 4	87 ± 6^b
Monocytes^a	1 ± 2	1 ± 2	2 ± 2	2 ± 2	3 ± 2^b
Females
Potassium (mmol/L)	4.96 ± 0.35	4.68 ± 0.24	4.58 ± 0.41	4.51 ± 0.37^b	4.45 ± 0.40^b
Lymphocytes^a	92 ± 3	88 ± 5	86 ± 6^b	85 ± 7^b	86 ± 3^b

^apercent of total white blood cells.

^bSignificantly different from untreated controls.

^cSignificantly different from sham-exposed controls.

^dSignificantly different from both control groups.

Conclusions:

Subchronic exposure to 3300 ppm diisopropyl ether lead to only minor weight changes in liver and kidneys. Subchronic exposure to 7100 ppm diisopropyl ether lead to increased weight changes, accompanied by small morphological changes. Diisopropyl ether demonstrated relatively low toxicity for the endpoints evaluated. Therefore, the NOAEC was set to 3300 ppm and the NOEC to 480 ppm.

Executive summary:

Read across from diisopropylether (DIPE) is justified on the basis that NOAECs reported for the constituents of this UVCB range from 3500 mg/m³ for hexanol to 31680 mg/m³ for propylene dimers, which can be considered indicative of low toxicity for this UVCB substance. DIPE comprises approximately 50% of the UVCB substance and is, therefore, the main constituent. The C6 alkanes/alkenes are, with 20%, the second largest constituent. The NOAECs of both DIPE and C6 alkanes/alkenes, together accounting for approximately 70% of the UVCB substance, are in the same order of magnitude (3300 ppm and 3000 ppm, respectively).

Mild hypertrophy was observed at the high-dose in combination with 39% (male) and 18% (female) increased absolute liver weight. The high dose of 7100 ppm was considered to be the LOAEC effect level.

At the mid-dose, no histopathological changes were observed. Absolute liver weight gain was 26% in males only; 6% in females. Sorbitol dehydrogenase dropped from 11(5) or 16(7) IU/L in controls to 9(3) IU/L. The absolute liver weight gain seen only in males, and unaccompanied by other effects, is considered to be a suitable NOAEC.

Based on "adverse liver effects" criteria by TERA (Toxicology Excellence for Risk Assessment): presence of histopathology (moderate hypertrophy) in combination with statistically significant absolute or relative weight changes; or liver weight change >10%; or doubling of serum levels of liver enzyme activity.

Endpoint conclusion

Endpoint conclusion:

no adverse effect observed

Dose descriptor:

NOAEC

29 700 mg/m³

Study duration:

subchronic

Species:

rat

Quality of whole database:

The information for this endpoint was taken from a well-constructed 90-day inhalation toxicity study in rats with DIPE at exposure levels of 0 (controls), 480, 3300 and 7100 ppm (equivalent to 0, 2000, 13800 and 29700 mg/m3). The study was controlled with a group of rats receiving air only and also a sham-exposed group. For the read-across substance, DIPE, the presence of hepatotoxicity and renal toxicity was detected in males and, to a reduced extent, females at both the high dose level of 7100 ppm and the intermediate dose level of 3300 ppm. The NOAEC for local toxicity was considered to be the highest dose level tested of 7100 ppm.

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

The substance Reaction Products of C3 alcohols and C3 alkenes obtained as by-products from the manufacture of propan-2-ol by hydration of propylene is a UVCB substance. The main constituent (approximately 50%) is isopropyl ether. Minor constituents are propylene dimers (~20%, C6 hydrocarbons, mainly C6 alkenes), propylene trimers (~10%, C9 hydrocarbons), hexanols (~10%) and C3 alcohols (~10% consisting of both isopropanol and n-propanol).

The toxicological properties of the UVCB substance after repeated exposure can be predicted based on the toxicological properties of its main constituents after repeated exposure.

 

The repeated dose toxicity of isopropyl ether (IPE, also known as diisopropylether or DIPE) has extensively been assessed in several inhalation studies in multiple species, including rats, guinea pigs, rabbits and monkeys. In the most recent and well-described study, rats were exposed to 0, 480, 3300, and 7100 ppm IPE for 6 hours/day, 5 days/wk for 13 weeks. Increases in liver and kidney weights were seen at 3300 and 7100 ppm in both males and females. Some evidence of increased incidence of hyaline droplets in kidney proximal tubules was observed in high dose males only. No effects on serum chemistry, hematology, or pathology were noted at any dose level. The no observed effect concentration (NOEC) for this study was 480 ppm (Dalbey and Feuston, 1996). The authors did not derive a NOAEC, however, based on minimal kidney effects in the high-dose males, of which the relevance to man is unclear, a conservative NOAEC could be established at 3300 ppm (equivalent to 13,800 mg/m³).

Data from a developmental toxicity study with IPE confirm this NOAEC. Rats were administered 0, 430, 3095, and 6745 ppm IPE for 6 hours/day on gestations days 6-15. Maternal effects at the high dose included increased salivation and lacrimation during and immediately following exposure. A slight decrease in food consumption was noted at 3095 and 6745 ppm. A concentration-related increase in the incidence of rudimentary ribs was observed (statistically significant at 3095 and 6745 ppm), but the biological significance of this finding is not known. No changes in reproductive organ weights and structure or sperm and spermatid number at any dose group were noted. The NOEC for both maternal and developmental effects under conditions of this study was 430 ppm (Dalbey and Feuston, 1996). The authors did not derive a NOAEC, but since no significant adverse effects were noted at all concentrations, the NOAEC could be established at 6745 ppm.

 

Data on propylene dimers can be derived by reading across from data on C6 alkanes and C6 alkenes.  Information on the repeated dose toxicity for C6 alkanes can be derived from a 2-year carcinogenicity study of commercial hexane. Commercial hexane contains approximately 52% of n-hexane, and for the remaining 48% hexane isomers, including 2-methyl pentane.

In a two part study, the oncogenic effects of inhalation exposure to commercial hexane (approximately 52% n-hexane) were evaluated male and female mice and male and female rats (Daughtrey, 1999). In Part I of the study groups of 50 male and 50 female rats were exposed to 0, 900, 3000, or 9016 ppm of test substance for 6 hrs/day, 5 days/week, for 2 yrs. Mortalities of exposure groups were consistent with control groups. Body weight gain was significantly reduced in exposure groups. Histopathology revealed dose-related irritation-related effects in the nasoturbinal tissue in all exposure groups. Therefore, there was no NOAEC level for local irritation effects. The LOAEC level for both sexes was 900 ppm for irritation. No oncogenic effects were seen in the exposure groups. The NOAEC for systemic effects was 9016 ppm in rats of both sexes.

In Part II of the study groups of 50 male and 50 female mice were exposed to 0, 900, 3000, or 9018 ppm (0, 3168, 10560, 31680 mg/m³) of commercial hexane (52% n-hexane) for 6 hrs/day, 5 days/week, for 2 yrs. Mortalities of exposure groups were consistent with control groups. Histopathology revealed increased liver masses and nodules in female mice at the 9018 ppm exposure group. As referenced by the National Toxicology Program, liver tumors in B6C3F1 mice are known to be sensitive to body weight changes, especially in female B6C3F1 mice. Therefore, the increased incidence of liver masses and nodules in female mice are deemed of questionable relevance for human health risk assessment.  Therefore, the NOAEC level for oncogenic effects in mice is 9018 ppm (31,680 mg/m³).

Additional information confirming the low repeated dose toxicity potential of 2-methyl pentane can be derived from a two-generation reprotoxicity study on commercial hexane. In this study the effect of inhalation of commercial hexane (52% n-hexane) on reproduction in rats was determined (Daughtrey, 1994). Groups of 25 male and 25 female rats were exposed to nominal concentrations of 0, 900, 3000, or 9000 ppm of commercial hexane for 6 h a day, 5 or 7 days a week, over two generations. In addition to pre-breed exposures of 10 weeks' duration, exposures continued through mating, gestation and lactation. Reproductive parameters were similar in exposure groups and control groups. There was reduced body weight in the F1 and F2 generation in both sexes in the 9000 ppm exposure group in both adults and offspring. The NOAEC is therefore 3000 ppm (10,560 mg/m³), and the LOAEC is 9000 ppm (31680 mg/m³). Since there were no adverse effects in offspring without adverse maternal effects, the NOAEC for reproduction is 9000 ppm (31,680 mg/m³).

 

A 90-day inhalation study with hex-1-ene is representative for the C6 alkene repeated dose toxicity. In this study, Neodene 6 alpha olefin was administered to forty Fischer 344 rats/sex/concentration by dynamic whole body exposure at concentrations of 0, 300, 1000, or 3000 ppm (corresponding to 0, 1033, 3442, or 10,326 mg/m³) for 6 hours a day, 5 days a week, for 13 weeks (Bennick et al., 1984). Ten of the animals/sex/concentration were used for neuromuscular testing, ten of the animals/sex/concentration were sacrificed after 7 weeks of exposure, and twenty animals/sex/concentration were sacrificed after 13 weeks of exposure.

Subchronic inhalation of Neodene 6 alpha olefin for 13 weeks did not produce any adverse respiratory, neuromuscular, or testicular effects in rats. Decreased body weight was observed in 3000 ppm females (statistically significant) and males (statistically significant only sporadically). Decreased absolute liver and kidney weights were observed in 3000 ppm females; however, these findings were considered secondary to reduced body weight in the absence of histopathological findings in these organs. There were statistically significant differences in haematology and clinical chemistry values, but the changes were slight (generally within 5% of the control), were not dose related, and/or not associated with any histopathology findings. Increased phosphorus levels were reported in males at all treatment levels and females exposed to 1000 and 3000 ppm hex-1-ene. The toxicological significance of these findings is doubtful. The NOAEC is 3000 ppm (10,326 mg/m³) based on a lack of toxicologically relevant findings at the highest concentration tested.

 

Data on propylene trimers can be derived by reading across from data on C9 alkanes and C9 alkenes.

A 13-week inhalation toxicity study was conducted using wholly vaporized light alkylate naphtha distillate (a stream containing mainly C7-9 alkanes) (Schreiner et al., 1998). Male and female rats were exposed by inhalation in whole-body exposure cages 6 hours/day, 5 days/week for 13 weeks at analytical concentrations of 0, 668, 2220, and 6646 ppm. No test-related observations were noted in the exposure chambers during

any exposure period for any treatment groups or during non-exposure periods. From weekly clinical observations, the only apparent treatment-related finding was an increased incidence of red facial staining in both male and female rats in the high dose group. At week 13, there were statistically significant dose-related increases in absolute and relative kidney weights in males of all 3 treatment groups. The kidney weights of high-dose males remained elevated after the recovery period. These increases correlated with microscopic observations of hyaline droplet formation in the proximal convoluted tubules considered to contain an alpha2-microglobulin-hydrocarbon complex as well as an increase in incidence and severity of nephropathy and dilated tubules at the corticomedullary junction. These microscopic finding are characteristic of light hydrocarbon nephropathy also known as hyaline droplet nephropathy and are male rat specific. Therefore these effects are not considered to be relevant to humans. Statistically significant increases in absolute and relative liver weights were observed in high-dose male and female rats at week 13 after sacrifice. Differences were not present after the recovery period and had no microscopic correlate. Thus, the NOAEC for systemic toxicity was 8117 mg/m³ corresponding to 2200 ppm.

These findings are supported by a 13-week inhalation study (similar to OECD 413) with hydrocarbons, C7-C9, n-alkanes, isoalkanes, cyclic, which were administered via whole body inhalation to male rats at concentrations of 0, 280, 600, and 1200 ppm for 6 hours/day, 5 days/week, for 13

weeks (Carpenter et al., 1975). The NOAEC was estimated to be 5800 mg/m³ corresponding to 1200 ppm, the highest dose tested.

 

Information on the repeated dose toxicity for hexanol can be derived from a thirteen-week dietary feeding study in the rat. In this study rats were exposed to 1-hexanol via the diet (1% to 6%) during a 13 week treatment period. No signs of toxicity were recorded at diet concentrations of 1%. No microscopic alterations were recorded at any treatment level.  Examination of the testes and ovaries did not reveal any abnormality. The NOAEL was established at 1%, equivalent to 1127 mg/kg bw (ECB, 2000).

Information confirming the low repeated dose toxicity potential of hexanol can be derived from a developmental toxicity study, in which inhalation of saturated vapours of 1-hexanol (3500 mg/m³, 7 hr/day, GD 1-19) resulted in no significant signs of maternal or foetal toxicity. The NOAEC for both maternal and fetal effects for this study was the limit dose of 3500 mg/m³(Nelson et al., 1989).

 

Long-term repeated dose data on C3 alcohols are derived from isopropanol. No suitable long-term data on n-propanol could be located.

A GLP whole-body inhalation oncogenicity study in Fischer 344 rats with isopropanol concentrations of 0, 500, 2500, 5000 ppm for 6 hours/day 5 days/week for 104 weeks was conducted according to OECD test guideline 451 (Bushy Run Research Center, 1994). The report allows to conclude on a NOAEC of 5000 ppm (equivalent to 12,500 mg/m³). Exposure of rats to isopropanol vapour for 24 months produced clinical signs of toxicity, changes in body weight, and urinalysis and urine chemistry indicative of kidney changes in the 2500 and 5000 ppm groups. These changes were considered by the study authors to be indicative of chronic progressive nephropathy (CPN), a spontaneous lesion in aging rats which tends to be more prominent in male than female rats. Based on human and animal evidence relating to CPN, Hard et al. (2009; Gordon C. Hard, Kent J. Johnson, Samuel M. Cohen; Critical Reviews in Toxicology; 2009, Vol. 39, No. 4, Pages 332-346; A comparison of rat chronic progressive nephropathy with human renal disease) have concluded that this is a rodent-specific lesion which should not be regarded as an indicator of human toxic hazard. The only neoplastic lesion which was elevated was an increase in Leydig cell tumours in male rats. This is also a common spontaneous lesion in male rat which is very common in the rat strain used for this evaluation, F-344. The authors observed that the statistical significance attached to the frequency of this observation was probably due to the unusually low incidence in the concurrent control group. No increase in neoplastic lesions were noted in female rats.

 

Taking all repeated dose toxicity information of the constituents together, the NOAECs observed ranged from 3500 mg/m³ for hexanol to 31,680 mg/m³ for propylene dimers This indicates that the UVCB substance is of low repeated dose toxicity and does not require classification for repeated dose toxicity.

 

References

Bennick, J. E., Malley, L. A., Patterson, D. R., Lu, C. C. (1984). 90-Day vapor inhalation study in rats with Neodene® 6 alpha olefin. Testing laboratory: Westhollow Research Center, Houston, Texas. Report no.: WRC RIR-362. Owner company: Shell Development Company. Report date: 1984-04-03.

 

Bushy Run Research Center (1994). Isopropanol Vapor Inhalation Oncogencity Study in Fischer 344 Rats. Testing laboratory: Bushy Run Research Center, 6702 Mellon Road, Export Pennsylvania 15632-8902. Report no.: 91N0133. Owner company: American Chemistry Council, Inc. Report date: 1994-06-02

 

Carpenter, C. et al. (1975). Petroleum hydrocarbon toxicity studies II. Animal and human response to vapours of varnish makers and painters naphtha. Tox. Appl. Pharmacol. 32: 263-281.

 

Dalbey W. and Feuston M. (1996) Subchronic and developmental toxicity studies of vaporized diisopropyl ether. J. Toxicol. Environ. Health 49: 29-43.

 

Daughtrey W.C., Neeper-Bradley T., Duffy J., Haddock L., Keenan T., Kirwin C., and Soiefer A. (1994) Two-generation reproduction study on commercial hexane solvent. J. Appl. Toxicol. 14(5):387-393.

 

Daughtrey W., Newton P., Rhoden R., Kirwin C., Haddock L., Duffy J., Keenan T., Richter W., and Nicolich M. (1999) Chronic inhalation carcinogenicity study of commercial hexane solvent in F-344 rats and B6C3F1 mice. Toxicol. Sci. 48(1):21-29.

 

European Chemicals Bureau – ECB (2000) IUCLID Data Set, Hexan-1-ol (CAS#: 111-27-3). Citing: Scientific Associates, Inc. (1966) Exhibit II. Final report on thirteen-week subacute feeding of Alfol 6 and Alfol 16 to rats.

 

Hine C., Anderson H., and Kodama J. (1955) Sensory thresholds of certain Shell organic solvents, Progress Report 1, Report to Shell Development Company, November 15, UC Report #247.

 

Nelson B.K., Brightwell W.W., Khan A., Krieg E.F., Jr., and Hoberman A.M. (1989) Developmental toxicology evaluation of 1-pentanol, 1-hexanol, and 2-ethyl-1-hexanol administered by inhalation to rats. J. Am. Coll. Toxicol. 8(2):405-410.

 

Schreiner, C. et al. (1998). Toxicity evaluation of petroleum blending streams: inhalation subchronic toxicity/neurotoxicity study of a light alkylate naphtha distillate in rats. J. Toxicol. Env. Health (Part A) 55:277-296.

 

Silverman L., Schulte F., and First M. (1946) Further studies on sensory response to certain industrial solvent vapors. J. Ind. Hyg. Toxicol. 28(6):262-266.

Justification for classification or non-classification

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