1-(2-butoxy-1-methylethoxy)propan-2-ol

Endpoint summary

Description of key information

GLP-studies according to or equivalent to OECD guidelines 401, 403 and 402 (limit test) are available for DPnB.

Key value for chemical safety assessment

Acute toxicity: via oral route

Link to relevant study records

Reference

Endpoint:

acute toxicity: oral

Type of information:

experimental study

Adequacy of study:

key study

Study period:

February-July 1987

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: GLP study according to OECD guideline

Reason / purpose for cross-reference:

reference to same study

Reason / purpose for cross-reference:

reference to other study

Qualifier:

according to guideline

Guideline:

OECD Guideline 401 (Acute Oral Toxicity)

Deviations:

no

Principles of method if other than guideline:

n/a

GLP compliance:

yes

Test type:

standard acute method

Limit test:

no

Species:

rat

Strain:

Wistar

Sex:

male/female

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Source: Charles River Wiga GmbH
- Age at study initiation: approximately 8 weeks
- Weight at study initiation: 225-304 g (males), 172-201 g (females)
- Fasting period before study: feed was withheld overnight before dosing
- Housing: individually housed in polycarbonate cages 7 days prior to dosing
- Diet (e.g. ad libitum): ad libitum, standard laboratory animal diet (RMH-B)
- Water (e.g. ad libitum): ad libitum
- Acclimation period: 7 days


ENVIRONMENTAL CONDITIONS
- Temperature (°C): 20-23
- Humidity (%): 50-70%
- Air changes (per hr): n/a
- Photoperiod (hrs dark / hrs light): 12 hrs dark/ 12 hrs light


IN-LIFE DATES: From: 1987-Feb-17 (range-finding) and 1987-Feb-24 To: 1987-Feb-24 (range finding) and 1987-March-10

Route of administration:

oral: gavage

Vehicle:

unchanged (no vehicle)

Details on oral exposure:

VEHICLE
- Concentration in vehicle: n/a
- Amount of vehicle (if gavage): n/a
- Justification for choice of vehicle: n/a
- Lot/batch no. (if required): n/a
- Purity: n/a


MAXIMUM DOSE VOLUME APPLIED: 20 ml/kg bw for aqueous material


DOSAGE PREPARATION (if unusual): n/a


CLASS METHOD (if applicable)
- Rationale for the selection of the starting dose: n/a

Doses:

3200, 4200 and 5600 mg/kg bw

No. of animals per sex per dose:

5

Control animals:

no

Details on study design:

- Duration of observation period following administration: 14 days
- Frequency of observations and weighing: daily clinical observation except for weekends (observe for death only), Body weights were recorded prior to dosing, at death, or weekly thereafter.
- Necropsy of survivors performed: yes
- Other examinations performed: clinical signs, body weight

Statistics:

n/a

Preliminary study:

n/a

Sex:

male/female

Dose descriptor:

LD50

Effect level:

4 000 mg/kg bw

95% CL:

3 200 - 4 600

Sex:

male

Dose descriptor:

LD50

Effect level:

4 400 mg/kg bw

Sex:

female

Dose descriptor:

LD50

Effect level:

3 700 mg/kg bw

95% CL:

2 500 - 4 800

Mortality:

At the low dose of 3200 mg/kg DPnB, one male died on day 0 and one female died on day one (total mortality 2/10).  At 4200 mg/kg, two males and two females died on day 0 and two additional females died on day 1 (total mortality 6/10).  At 5600 mg/kg, four males and four females died on day 0 and one additional female died on day 1 (total mortality 9/10). 
All deaths occurred within two days of dosing.  Females were affected more than males.  

Clinical signs:

other: Adverse signs included weight loss, lethargy, coma, hypopnea, hyperpnea, dacryorrhea, blood around the eyes, rough coat, and ataxia.  Surviving rats showed no adverse signs by day 2.  

Gross pathology:

At necropsy, (presumably non-surviving) rats showed 1) enlargement, hemorrhage, and hyperemia of the stomach, 2) hemorrhage of the thymus, 3) dark red lungs, 4) dark red liver, and 5) gas accumulation, bloody content, and watery content of the small intestine.

Other findings:

- Organ weights: n/a
- Histopathology: n/a
- Potential target organs: n/a
- Other observations: n/a

The calculated oral LD50 for males alone was 4400 mg/kg (no 95% confidence limits), for females alone was 3700 mg/kg
(95% CL: 2500 - 4800 mg/kg), and for both sexes combined was 4000 mg/kg (95% CL: 3200 - 4600 mg/kg).

Interpretation of results:

GHS criteria not met

Remarks:

Criteria used for interpretation of results: EU

Conclusions:

The substance is not classified for acute oral toxicity according to EU criteria as the lowest LD50 is 3700 mg/kg.

Executive summary:

Three groups of Wistar rats (5/sex/dose level) received single oral doses of 3200, 4200, or 5600 mg/kg dipropylene glycol n-butyl ether (DPnB), administered undiluted using a stainless steel stomach cannula attached to a syringe. 

Animals were fasted overnight prior to dosing and were not allowed food until 4.5-5.0 hr after dosing.  Subjects were observed for mortality and signs of toxicity several times on the day of dosing (Day 0) and on weekdays thereafter for
up to 14 additional days.  Body weights were recorded prior to dosing, at death, or weekly thereafter.  

Non-survivors were necropsied as soon as possible and surviving animals were sacrificed by CO₂ asphyxiation and subjected to necropsy on day 15.

At the low dose of 3200 mg/kg DPnB, one male died on day 0 and one female died on day one (total mortality 2/10).  At
4200 mg/kg, two males and two females died on day 0 and two additional females died on day 1 (total mortality 6/10).  At
5600 mg/kg, four males and four females died on day 0 and one additional female died on day 1 (total mortality 9/10). 

The calculated oral LD₅₀ for males alone was 4400 mg/kg (no 95% confidence limits), for females alone was 3700 mg/kg
(95% CL: 2500 - 4800 mg/kg), and for both sexes combined was 4000 mg/kg (95% CL: 3200 - 4600 mg/kg).

All deaths occurred within two days of dosing.  Females were affected more than males.  Adverse signs included weight loss, lethargy, coma, hypopnea, hyperpnea, dacryorrhea, blood around the eyes, rough coat, and ataxia.  Surviving rats showed no adverse signs by day 2.  Weight gain appeared normal in survivors.  At necropsy, (presumably non-surviving) rats showed 1) enlargement, hemorrhage, and hyperemia of the stomach, 2) hemorrhage of the thymus, 3) dark red lungs, 4) dark red liver, and 5) gas accumulation, bloody content, and watery content of the small intestine.

The calculated oral LD₅₀ for males alone was 4400 mg/kg (no 95% confidence limits), for females alone was 3700 mg/kg
(95% CL: 2500 - 4800 mg/kg), and for both sexes combined was 4000 mg/kg (95% CL: 3200 - 4600 mg/kg).

The substance is not classified for acute oral toxicity according to EU criteria as the lowest LD₅₀ is 3700 mg/kg.

Endpoint conclusion

Endpoint conclusion:

adverse effect observed

Dose descriptor:

LD50

Value:

3 700 mg/kg bw

Quality of whole database:

Good (Klimisch 1)

Acute toxicity: via inhalation route

Link to relevant study records

Reference

Endpoint:

acute toxicity: inhalation

Type of information:

experimental study

Adequacy of study:

key study

Study period:

April-November 1990

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: GLP study equivalent to OECD guideline 403

Reason / purpose for cross-reference:

reference to other study

Qualifier:

according to guideline

Guideline:

OECD Guideline 403 (Acute Inhalation Toxicity)

Deviations:

no

Principles of method if other than guideline:

Method: other: Protocol guideline not specified in report. However, protocol meets criteria in OECD 403 "Acute Inhalation Toxicity."

GLP compliance:

yes

Test type:

standard acute method

Limit test:

no

Species:

rat

Strain:

Fischer 344

Sex:

male/female

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Source: Charles River Breeding Laboratories
- Age at study initiation: 9 weeks
- Weight at study initiation: males: around 200 g, females: 120-130 g.
- Fasting period before study: none
- Housing: 2 per stainless steel wire cage prior to exposure and 1 per cage post exposure
- Diet (e.g. ad libitum): ad libitum
- Water (e.g. ad libitum):ad libitum
- Acclimation period: 3 weeks in house. prior to exposure, animals were acclimated in nose-only apparatus without test material exposure for 4 hours.


ENVIRONMENTAL CONDITIONS
- Temperature (°C): as regulated
- Humidity (%): as regulated
- Air changes (per hr): n/a
- Photoperiod (hrs dark / hrs light): 12/12


IN-LIFE DATES: From: To: n/a

Route of administration:

inhalation: aerosol

Type of inhalation exposure:

nose only

Vehicle:

other: unchanged (no vehicle)

Details on inhalation exposure:

In an acute inhalation toxicity study, a single group of 5 male and 5 female young adult Fischer 344 rats were exposed to an aerosol atmosphere of DPnB, at a concentration of 2040 mg/m3, by nose-only exposure for a period of 4 hours.  

Polycarbonate tubes containing the subjects (nose cones) were attached to a 42-liter ADG nose-only inhalation chamber (30 x 60 cm) with an airflow of 30 liters/min.  Aerosol was generated by metering DPnB into a stainless steel ¼ J spray nozzle using a FMI pump.  DPnB was mixed with air in the spray nozzle and test material was sprayed into the chamber as an aerosol.  Aerosol total mass concentrations were measured gravimetrically five times over the 4-hour exposure.  Aerodynamic particle size was characterized using a 6-stage cascade impactor with increasingly diminishing pore sizes in the 6 stages.  Temperature and humidity were monitored at ½ hour intervals over the 4-hour exposure.

Analytical verification of test atmosphere concentrations:

yes

Duration of exposure:

4 h

Concentrations:

2040 mg/m3

No. of animals per sex per dose:

5

Control animals:

no

Details on study design:

Rats were observed for mortality and clinical signs of toxicity on the day of exposure (day 1) and 14 days thereafter.  The subjects were weighed on days 1, 2, 4, 8, 11, and 15 of the study.  All animals were subjected to gross necropsy.

Statistics:

Means and standard deviations of body weights, chamber temperatures, relative humidity and airflows, and chamber concentrations were calculated for descriptive purpose.

Preliminary study:

n/a

Sex:

male/female

Dose descriptor:

LC0

Effect level:

> 2.04 mg/L air

Exp. duration:

4 h

Mortality:

All rats survived the first day of exposure as well as the subsequent 14-day observation period (i.e., until the scheduled sacrifice on day 15).  

Clinical signs:

other: Immediately after exposure, rats were soiled with urine and feces from being in the nose cones. 

Body weight:

Body weights for both sexes were slightly decreased (3%) on the day after exposure but gained weight steadily thereafter (not unusual with nose-only exposures).

Gross pathology:

No gross pathological changes were noted in any subjects at necropsy.

Other findings:

Characterization of the aerosol atmosphere:  The time weighted average concentration of the aerosol over the 4-hour exposure period was 2.04 mg/liter or 2,040 mg/m3. Forty-eight percent of the aerosol had an aerodynamic mass median diameter of less than 3 microns, indicating that a high percentage of the aerosol was respirable within the deep lung.

none

Interpretation of results:

GHS criteria not met

Remarks:

Criteria used for interpretation of results: EU

Conclusions:

The lethal concentration of DPnB is greater than 2.04 mg/liter (2,040 mg/m3). If DPnB had sufficient vapor pressure, this concentration would correspond to 262 ppm.

Executive summary:

In an acute inhalation toxicity study, a single group of 5 male and 5 female young adult Fischer 344 rats were exposed
to an aerosol atmosphere of DPnB, at a concentration of 2040 mg/m3, by nose-only exposure for a period of 4 hours.  Rats
were observed for mortality and clinical signs of toxicity on the day of exposure (day 1) and 14 days thereafter.  The
subjects were weighed on days 1, 2, 4, 8, 11, and 15 of the study.  All animals were subjected to gross necropsy.

Polycarbonate tubes containing the subjects (nose cones) were attached to a 42-liter ADG nose-only inhalation chamber
(30 x 60 cm) with an airflow of 30 liters/min.  Aerosol was generated by metering DPnB into a stainless steel ¼ J spray
nozzle using a FMI pump.  DPnB was mixed with air in the spray nozzle and test material was sprayed into the chamber
as an aerosol.  Aerosol total mass concentrations were measured gravimetrically five times over the 4-hour
exposure.  Aerodynamic particle size was characterized using a 6-stage cascade impactor with increasingly diminishing
pore sizes in the 6 stages.  Temperature and humidity were monitored at ½ hour intervals over the 4-hour exposure.

Rats were acclimated to the nose-only polycarbonate tubes for four hours the day prior to exposure.  Rats showed
typical transient weight loss due to stress from being confined in the tubes.

All rats survived the first day of exposure as well as the subsequent 14-day observation period (i.e., until the scheduled sacrifice on day 15).  Immediately after exposure, rats were soiled with urine and feces from being in the nose
cones.  Body weights for both sexes were slightly decreased (3%) on the day after exposure but gained weight steadily
thereafter (not unusual with nose-only exposures).  No gross pathological changes were noted in any subjects at necropsy.

Characterization of the aerosol atmosphere:  The time weighted average concentration of the aerosol over the 4-hour exposure period was 2.04 mg/liter or 2,040 mg/m3. Forty-eight percent of the aerosol had an aerodynamic mass
median diameter of less than 3 microns, indicating that a high percentage of the aerosol was respirable within the deep lung.

The lethal concentration of DPnB is greater than 2.04 mg/liter (2,040 mg/m3). If DPnB had sufficient vapor pressure, this concentration would correspond to 262 ppm.

This study was identified as key for this toxicity endpoint because of the methods followed (which were comprehensively
documented in the report).  The report included GLP and Quality Assurance statements, signed by the Study Director
and Head of the QA Unit, respectively.  Although the study report did not specify that OECD Protocol 403: "Acute
Inhalation Toxicity"  was followed, the study satisfied the methods stipulated in Protocol 403.  Specifically, the numbers and type of test animals used and their husbandry conditions were as prescribed in the guidance.  Test
material characterization was adequate.  The dose level tested (in this limit test) satisfied the appropriate OECD
upper limit, the length of the observation period (14 days) was sufficient, and the toxicity endpoints monitored were
typical for this type assay and adequately recorded.

Endpoint conclusion

Endpoint conclusion:

no adverse effect observed

Quality of whole database:

Good (Klimisch 1)

Acute toxicity: via dermal route

Link to relevant study records

Reference

Endpoint:

acute toxicity: dermal

Type of information:

experimental study

Adequacy of study:

key study

Study period:

March-July 1987

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: GLP study according to OECD guideline 402

Reason / purpose for cross-reference:

reference to same study

Reason / purpose for cross-reference:

reference to other study

Qualifier:

according to guideline

Guideline:

OECD Guideline 402 (Acute Dermal Toxicity)

GLP compliance:

yes

Test type:

standard acute method

Limit test:

yes

Species:

rat

Strain:

Wistar

Sex:

male/female

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Source: Charles River GmbH
- Age at study initiation: about 8 weeks
- Weight at study initiation: Males: 308-356 g, Females: 211-225 g
- Fasting period before study: none
- Housing: individually housed 7 days prior to testing
- Diet (e.g. ad libitum): ad libitum
- Water (e.g. ad libitum):ad libitum
- Acclimation period: 7 days


ENVIRONMENTAL CONDITIONS
- Temperature (°C): 20-21
- Humidity (%): 30-70
- Air changes (per hr): n/a
- Photoperiod (hrs dark / hrs light): 12/12


IN-LIFE DATES: From: To: n/a

Type of coverage:

semiocclusive

Vehicle:

unchanged (no vehicle)

Details on dermal exposure:

A group of 5 male and 5 female Wistar rats (~7 weeks old) was treated with a single dose of 2,000 mg/kg dipropylene glycol n-butyl ether applied topically to the intact skin under occlusion for a period of 24 hours. 

Duration of exposure:

24 hours

Doses:

2000 mg/kg bw

No. of animals per sex per dose:

5

Control animals:

no

Details on study design:

Subjects were observed for clinical signs of toxicity and mortality during the application period and for a period of 14 days after removal of the test material.  The skin of the rats at the site of application was also evaluated for signs of irritation over the course of the study.  The pure test material was applied at a single dose of 2,000 mg/kg to approximately 10% of the total body surface area of skin (clipped, non-abraded) of the rats.  The test material was applied to gauze patches, which were then affixed to the clipped area of the skin and covered with foil and wrapped with a bandage around the torso.  The test material was held in contact with the skin for a period of 24 hours whereupon it was removed and the treated area was washed with water to remove remaining test material.  On the day of treatment (day 0), animals were observed frequently for toxicity and morbidity.  Thereafter, subjects were checked once daily except for weekends and holidays.  Individual body weights were recorded on test days 0, 7, and 14.  The treated areas of skin were examined on test days 4, 7, and 14 for signs of irritation.  Animals were sacrificed on day 14 and subjected to gross necropsy.

Statistics:

none

Preliminary study:

n/a

Sex:

male/female

Dose descriptor:

LD0

Effect level:

> 2 000 mg/kg bw

Mortality:

No deaths occurred over the course of the study. 

Clinical signs:

other: No clinical signs of toxicity or skin irritation occurred over the course of the study. 

Gross pathology:

No test material related gross abnormalties were identified.

Other findings:

none

The dermal LD50 for dipropylene glycol n-butyl ether is greater than 2,000 mg/kg for male and female Wistar rats.

Interpretation of results:

GHS criteria not met

Remarks:

Criteria used for interpretation of results: EU

Conclusions:

The substance is not classified for acute dermal toxicity according to EU criteria as the LD50 is greater than 2 000 mg/kg bw.

Executive summary:

A group of 5 male and 5 female Wistar rats (~7 weeks old) was treated with a single dose of 2,000 mg/kg dipropylene glycol n-butyl ether applied topically to the intact skin under occlusion for a period of 24 hours.  Subjects were observed for clinical signs of toxicity and mortality during the application period and for a period of 14 days after removal of the test material.  The skin of the rats at the site of application was also evaluated for signs of irritation over the course of the study.  The pure test material was applied at a single dose of 2,000 mg/kg to approximately 10% of the total body surface area of skin (clipped, non-abraded) of the rats.  The test material was applied to gauze patches, which were then affixed to the clipped area of the skin and covered with foil and wrapped
with a bandage around the torso.  The test material was held in contact with the skin for a period of 24 hours whereupon
it was removed and the treated area was washed with water to remove remaining test material.  On the day of treatment
(day 0), animals were observed frequently for toxicity and morbidity.  Thereafter, subjects were checked once daily
except for weekends and holidays.  Individual body weights were recorded on test days 0, 7, and 14.  The treated areas
of skin were examined on test days 4, 7, and 14 for signs of irritation.  Animals were sacrificed on day 14 and subjected
to gross necropsy.

No deaths, clinical signs of toxicity, or skin irritation occurred over the course of the study.  The dermal LD50 for dipropylene glycol n-butyl ether is greater than 2,000 mg/kg for male and female Wistar rats.

Endpoint conclusion

Endpoint conclusion:

no adverse effect observed

Quality of whole database:

Good (Klimisch 1)

Additional information

The studies with a Klimisch rating 1 or 2 have been selected as key studies for the hazard assessment.

Two GLP-studies according to or equivalent to OECD guideline 401 report oral LD50 values of 3700 (Dow-1987 study) and 2160 (BASF-1988 study) mg/kg bw. In addition two non-GLP studies similar to OECD guideline 401 estimates the oral LD50 to be between 1820 and 2730 mg/kg bw or at 2610 mg/kg bw, respectively. The value from the key study will be taken forward to the risk assessment. According to the EU criteria for classification and labelling requirements as laid down in Annex 6 of the EEC Council Directive 67/548 EEC (amended by Directive 83/467 EEC) and in accordance with CLP (Guidance to Regulation (EC) No. 1272/2008 on classification, labelling and packaging (CLP) of substances and mixtures, dipropylene glycol n-butyl ether will not be classifed for acute oral toxicity.

A vapor- and an aerosol-inhalation study are available for dipropylene glycol butyl ether. Both studies were conducted under GLP and equivalent to OECD guideline 403. No mortality was observed up to the highest concentrations tested (42.1 ppm - highest attainable vapor concentration - (Dow-1987 study) and 2040 mg/m3 aerosol - (Dow-1990 study). This data is supported by a non-GLP vapor inhalation study equivalent to OECD guideline 403 reporting no mortality up the highest concentration tested (5.4 mg/l, BASF-1988 study). Hence, according to the EU criteria for classification and labelling requirements as laid down in Annex 6 of the EEC Council Directive 67/548 EEC (amended by Directive 83/467 EEC) and in accordance with CLP (Guidance to Regulation (EC) No. 1272/2008 on classification, labelling and packaging (CLP) of substances and mixtures, dipropylene glycol n-butyl ether will not be classifed for acute inhalation toxicity.

The dermal LD0 in a GLP-study according to OECD guideline 402 was determined to be greater than 2000 mg/kg bw (Dow-1987 study). This value is supported by a non-GLP study (BASF-1988 study) equivalent to OECD guideline 402. Hence, according to the EU criteria for classification and labelling requirements as laid down in Annex 6 of the EEC Council Directive 67/548 EEC (amended by Directive 83/467 EEC) and in accordance with CLP (Guidance to Regulation (EC) No. 1272/2008 on classification, labelling and packaging (CLP) of substances and mixtures, dipropylene glycol n-butyl ether will not be classifed for acute dermal toxicity.

Justification for selection of acute toxicity – oral endpoint
GLP study according to OECD TG 401

Justification for selection of acute toxicity – inhalation endpoint
GLP study equivalent to OECD TG 403

Justification for selection of acute toxicity – dermal endpoint
GLP study according to OECD TG 402

Justification for classification or non-classification

The oral LD50 in rats is greater than 2000 mg/kg bw and the dermal LD0 in rats is greater than 2000 mg/kg bw. Inhalation exposure to the highest attainable vapor concentration of DPnB (42.1 ppm or 328 mg/m3) did not reveal any substance related adverse effects. Inhalation exposure to the highest attainable aerosol concentration of DPnB (2040 mg/m3) did not indicate any substance related adverse effects, either.

Hence, according to the EU criteria for classification and labelling requirements as laid down in Annex 6 of the EEC Council Directive 67/548 EEC (amended by Directive 83/467 EEC) and in accordance with CLP (Guidance to Regulation (EC) No. 1272/2008 on classification, labelling and packaging (CLP) of substances and mixtures, dipropylene glycol n-butyl ether will not be classifed for any tested route of exposure (oral, inhalation and dermal).