2-(2-butoxyethoxy)ethyl acetate

Repeated dose toxicity: dermal

Administrative data

Endpoint:

sub-chronic toxicity: dermal

Type of information:

experimental study

Adequacy of study:

key study

Study period:

1993

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: A well conducted study where key information is reported.

Cross-reference

Reason / purpose for cross-reference:

reference to same study

Reference

Endpoint:

one-generation reproductive toxicity

Type of information:

experimental study

Adequacy of study:

supporting study

Study period:

1993

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

study well documented, meets generally accepted scientific principles, acceptable for assessment

Reason / purpose for cross-reference:

reference to same study

Qualifier:

equivalent or similar to guideline

Guideline:

OECD Guideline 415 [One-Generation Reproduction Toxicity Study (before 9 October 2017)]

Deviations:

yes

Remarks:

Animals treated for 13 weeks prior to mating. Not all end points examined

GLP compliance:

not specified

Limit test:

yes

Species:

rat

Strain:

other: Charles River CD

Sex:

male/female

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Source: Charles River Laboratories
- Age at study initiation: 6 wks
- Housing: individual in suspended stainless steel cages, except during mating and lactation period. During latter, solid steel pan fitted and hardwood shaving bedding added.
- Use of restrainers for preventing ingestion (if dermal): no data
- Diet (ad libitum): Certified Purina lab chow #5002 mash diet
- Water (ad libitum): tap
- Acclimation period: 2 weeks


ENVIRONMENTAL CONDITIONS
- Temperature (°C): 19-24
- Humidity (%): 30-70
- Photoperiod (hrs dark / hrs light): 12/12

Route of administration:

dermal

Vehicle:

unchanged (no vehicle)

Details on exposure:

TEST SITE
- Area of exposure: back
- % coverage: 3x3cm
- Type of wrap if used: polyethylene (PE) patch held in place by adhesive bandage wrapped around trunk of animal. Gauze pad added beneath PE patch after start of study
- Time intervals for shavings or clipplings:


REMOVAL OF TEST SUBSTANCE
- Washing (if done): wiped only.
- Time after start of exposure: 6hrs


TEST MATERIAL
- Amount(s) applied (volume or weight with unit): 2ml/kg bw/day based on an assumed density of 1g/ml (ie therefore 2g/kg bw/day.
- Concentration (if solution): neat
- Constant volume or concentration used: yes


USE OF RESTRAINERS FOR PREVENTING INGESTION: no data

Details on mating procedure:

- M/F ratio per cage: 1:1
- Length of cohabitation: overnight
- Proof of pregnancy: vaginal plug or sperm in vaginal smear
- After 10 days of unsuccessful pairing replacement of first male by another male with proven fertility.
- After successful mating each pregnant female was caged as previously until littering
- Any other deviations from standard protocol: No crossover was used. Mating only control/control and treatment/treatment male/females.

Analytical verification of doses or concentrations:

no

Details on analytical verification of doses or concentrations:

Not required as neat substance used.

Duration of treatment / exposure:

Exposure period: 90 days.
Premating exposure period (males): 90 days
Premating exposure period (females): 90 days
Females then treated throughout gestation and lactation period

Frequency of treatment:

6 hours/day, 5 day/week and then daily except for females during GD0-20 when 7 days/week

Details on study schedule:

no further information

Dose / conc.:

2 000 mg/kg bw/day

No. of animals per sex per dose:

25

Control animals:

other: yes, sham treatment with distilled water

Details on study design:

- Rationale for animal assignment (if not random): randomised but to keep mean body weights of control and treatment groups equal.

Positive control:

no

Parental animals: Observations and examinations:

BODY WEIGHT: Yes
- Mated females on GD0, 7, 14, 20 and lactating females on days 0, 7, 21 postpartum.

FOOD CONSUMPTION AND COMPOUND INTAKE (if feeding study):
- Food consumption monitored during each third of gestation period.

Oestrous cyclicity (parental animals):

Estrous cyclicity was monitored in a parallel repeat dose toxicity study. See section on cross references.

Sperm parameters (parental animals):

Not examined

Litter observations:

STANDARDISATION OF LITTERS
- Performed on day 4 postpartum: yes
- If yes, maximum of 8 pups/litter (4/sex/litter as nearly as possible); excess pups were killed and discarded.


PARAMETERS EXAMINED
The following parameters were examined in F1 offspring: number and sex of pups, presence of gross anomalies (monitored throughout lactation, weight gain.


GROSS EXAMINATION OF DEAD PUPS:
yes, for external abnormalities

Postmortem examinations (parental animals):

SACRIFICE (by exsanguination)
- Male animals: All surviving animals after completion of mating period.
- Maternal animals: All surviving animals after the last litter of each generation was weaned.


GROSS NECROPSY. Yes but no further details

HISTOPATHOLOGY / ORGAN WEIGHTS. Yes but selective
- Testes, epididymides, seminal vesicles, prostate glands and any gross lesions were prepared for microscopic examination.

Postmortem examinations (offspring):

SACRIFICE (ether overdose)
- on lactation day 21

GROSS NECROPSY
- Gross necropsy consisted of external and internal examinations

Statistics:

Body weights, feed consumption, organ weights using Bartlett's test to determine if variances equal. If variances equal, parametric procedures used (ANOVA followed by Dunnett's test if appropriate). Alternative non-parametric procedures were Kruskal-Wallis test follwed by Dunn's summed rank test if appropriate. Tests for trend using regression analysis and Jonckheere's test. Walsh's test used to determine equality of means. Indices compared using Fisher's exact test. Comparisons made at 1 and 5% signficance levels (two sided.)

Reproductive indices:

Mating indices, pregnancy rates, male fertility

Offspring viability indices:

Survival

Clinical signs:

not specified

Dermal irritation (if dermal study):

effects observed, treatment-related

Description (incidence and severity):

Dermal irritation occurred at the application site.

Body weight and weight changes:

no effects observed

Food consumption and compound intake (if feeding study):

no effects observed

Organ weight findings including organ / body weight ratios:

no effects observed

Histopathological findings: non-neoplastic:

no effects observed

Description (incidence and severity):

No effects on testes

Reproductive function: oestrous cycle:

no effects observed

Description (incidence and severity):

Results drawn from parallel repeat dose toxicity study where vaginal cytology was assessed.

Reproductive function: sperm measures:

not examined

Reproductive performance:

no effects observed

Description (incidence and severity):

No effects on male and female mating indices, pregnancy rates, male fertility indices.

Remarks on result:

not determinable due to absence of adverse toxic effects

Critical effects observed:

no

Clinical signs:

not specified

Mortality / viability:

no mortality observed

Body weight and weight changes:

no effects observed

Sexual maturation:

not specified

Organ weight findings including organ / body weight ratios:

not specified

Gross pathological findings:

no effects observed

Histopathological findings:

not specified

No effect on parturition data

Reproductive effects observed:

no

Conclusions:

There was no evidence of reproductive toxicity resulting from treatment of rats with 2-(2-butoxyethoxy)ethanol with a dermally applied dose of 2000mg/kg bw/day

Executive summary:

In a well conducted single generation fertility study, 2 -(2 -butoxyethoxy)ethanol produced no signs of toxicity to reproduction in either male or female rats when tested with a dermally dose of 2000mg/kg bw/day. The only finding that was dermal irritation resulting from repeated application of the test substance to the same application site.

Synopsis

Not toxic to reproduction

Data source

Reference

Reference Type:

publication

Title:

Toxicology of diethylene glycol butyl ether 4. Dermal subchronic/reproduction study

Author:

Auletta CS, Schroeder RE, Krasavage WJ, Stack CR

Year:

1993

Bibliographic source:

J Am coll. Toxicol. 12, 2, 161-168.

Materials and methods

Test guideline

Qualifier:

equivalent or similar to guideline

Guideline:

OECD Guideline 411 (Subchronic Dermal Toxicity: 90-Day Study)

Deviations:

yes

Remarks:

, not all end points apparently recorded

GLP compliance:

not specified

Limit test:

no

Test material

Test material information

Constituent 1

Reference substance name:

2-(2-butoxyethoxy)ethanol

EC Number:

203-961-6

EC Name:

2-(2-butoxyethoxy)ethanol

Cas Number:

112-34-5

Molecular formula:

C8H18O3

IUPAC Name:

2-(2-butoxyethoxy)ethanol

Details on test material:

- Name of test material (as cited in study report): ethylene glycol monobutyl ether (DGBE)
- Physical state: liquid
- Analytical purity: no data
- Stability under test conditions: confirmed a homogeneous and stable for 1 week
- Storage condition of test material: under nitrogen in refridgerator
- Other: supplied by Dow Chemical Co.

Test animals

Species:

rat

Strain:

other: Charles River CD

Sex:

male/female

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Source: Charles River Laboratories
- Age at study initiation: 6 wks
- Housing: individual in suspended stainless steel cages, except during mating and lactation period. During latter, solid steel pan fitted and hardwood shaving bedding added.
- Use of restrainers for preventing ingestion (if dermal): no data
- Diet (ad libitum): Certified Purina lab chow #5002 mash diet
- Water (ad libitum): tap
- Acclimation period: 2 weeks


ENVIRONMENTAL CONDITIONS
- Temperature (°C): 19-24
- Humidity (%): 30-70
- Photoperiod (hrs dark / hrs light): 12/12

Administration / exposure

Type of coverage:

occlusive

Vehicle:

water

Details on exposure:

TEST SITE
- Area of exposure: back
- % coverage: 3x3cm
- Type of wrap if used: polyethylene (PE) patch held in place by adhesive bandage wrapped around trunk of animal. Gauze pad added beneath PE patch after start of study
- Time intervals for shavings or clipplings:


REMOVAL OF TEST SUBSTANCE
- Washing (if done): wiped only.
- Time after start of exposure: 6hrs


TEST MATERIAL
- Amount(s) applied (volume or weight with unit): 2ml/kg
- Concentration (if solution): neat
- Constant volume or concentration used: yes

Analytical verification of doses or concentrations:

yes

Details on analytical verification of doses or concentrations:

Periodic analysis of diluted dosing solutions showed that 10% dose within 99.5(+/-3.1)% and 30% dose within 99.8(+/-2.6)%.

Duration of treatment / exposure:

13 weeks

Frequency of treatment:

6 hours/day, 5 days/week

Doses / concentrations

Doses / concentrations 1

Dose / conc.:

200 mg/kg bw/day

Doses / concentrations 2

Dose / conc.:

600 mg/kg bw/day

Doses / concentrations 3

Dose / conc.:

2 000 mg/kg bw/day

No. of animals per sex per dose:

10

Control animals:

yes

Details on study design:

- Rationale for animal assignment (if not random): randomised but to keep mean body weights of control and treatment groups equal.
- other: Post-exposure period: none

Positive control:

no

Examinations

Observations and examinations performed and frequency:

CAGE SIDE OBSERVATIONS: Yes
- Time schedule: twice daily checks for morbidity/mortality and overt toxic effects

DETAILED CLINICAL OBSERVATIONS: No data

DERMAL IRRITATION (if dermal study): Yes
- Time schedule for examinations: twice daily qualitative analysis at treatment (dosing) time and after wrapping removed.

BODY WEIGHT: Yes
- Time schedule for examinations: weekly

FOOD CONSUMPTION:
- Food consumption for each animal determined and mean daily diet consumption calculated as g food/kg body weight/day: Yes, weekly

FOOD EFFICIENCY:
- Body weight gain in kg/food consumption in kg per unit time X 100 calculated as time-weighted averages from the consumption and body weight gain data: Yes / No / No data

OPHTHALMOSCOPIC EXAMINATION: Yes
- Time schedule for examinations: pre-study and near end study

HAEMATOLOGY:
- Time schedule for collection of blood: Pre-study and at 4 and 13 weeks. Collected by venipuncture of orbital sinus.
- Anaesthetic used for blood collection: Yes
- Animals fasted: Yes, overnight and not dosed until after blood collection.
- How many animals: no data

CLINICAL CHEMISTRY: Yes
- Time schedule for collection of blood: Pre-study and at 4 and 13 weeks. Collected by venipuncture of orbital sinus.
- Animals fasted: Yes, overnight
- How many animals: No data

URINALYSIS: Yes / No / No data
- Time schedule for collection of urine: Pre-study and at 4 and 13 weeks
- Metabolism cages used for collection of urine: No data
- Animals fasted: No data

NEUROBEHAVIOURAL EXAMINATION: No

OTHER: During a 14 day period near the end of the study, daily vaginal smears were collected to dermine if normal oestrus cycle was occuring.

Sacrifice and pathology:

Sacrifice by ether anesthesia.
GROSS PATHOLOGY: Yes
HISTOPATHOLOGY: Yes, including adrenals, kidneys, pituitary, prostate, testes, epididymides, seminal vesicles, liver, ovaries and spleen. All weighed and fixed. High dose and control animal tissues sectioned for histology.

Other examinations:

none

Statistics:

Body weights, feed consumption, organ weights using Bartlett's test to determine if variances equal. If variances equal, parametric procedures used (ANOVA followed by Dunnett's test if appropriate). Alternative non-parametric procedures were Kruskal-Wallis test follwed by Dunn's summed rank test if appropriate. Tests for trend using regression analysis and Jonckheere's test. Walsh's test used to determine equality of means. Comparisons made at 1 and 5% signficance levels (two sided.)

Results and discussion

Results of examinations

Clinical signs:

effects observed, treatment-related

Description (incidence and severity):

One mid and one high dose animal had haematuria or red urinary staining on the haircoat.

Dermal irritation:

effects observed, treatment-related

Description (incidence and severity):

Concentration dependent increase in irritation worse in females. In females it was evident (erythema) from week 1 at the high dose and week 8 at the mid and high dose, with increasing numbers of animals affected with time. In males, it was only seen at the end of the study and and never effected more than 50% of animals. In males the severity was slight or very slight whilst in females there was necrosis and eschar in some animals at high doses.

Mortality:

no mortality observed

Body weight and weight changes:

no effects observed

Food consumption and compound intake (if feeding study):

no effects observed

Food efficiency:

not examined

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

not examined

Ophthalmological findings:

no effects observed

Haematological findings:

no effects observed

Clinical biochemistry findings:

no effects observed

Urinalysis findings:

effects observed, treatment-related

Description (incidence and severity):

Occult blood was noted in females treated at 600 or 2000  mg/kg but there was no evidence of urinary casts or significant numbers of erthyrocytes.

Behaviour (functional findings):

not examined

Organ weight findings including organ / body weight ratios:

no effects observed

Gross pathological findings:

no effects observed

Histopathological findings: non-neoplastic:

no effects observed

Histopathological findings: neoplastic:

no effects observed

Effect levels

1

Dose descriptor:

NOAEL

Effect level:

< 200 mg/kg bw/day

Based on:

test mat.

Sex:

male/female

Basis for effect level:

dermal irritation

2

Dose descriptor:

NOAEL

Effect level:

> 2 000 mg/kg bw/day

Based on:

test mat.

Sex:

male/female

Basis for effect level:

other: all other effects

Remarks on result:

not determinable due to absence of adverse toxic effects

Target system / organ toxicity

Critical effects observed:

not specified

Any other information on results incl. tables

Females appeared to be more susceptible than males to concentration-dependent irritation at the application site. Effects at the highest dosage were desquamation,  atonia, eschar and necrosis.

Applicant's summary and conclusion

Conclusions:

The only effect of note was dermal irritation at the site of repeated application which occured at all doses, albeit very slight at the low dose and only in males at towards the end of the study. Irritancy was more marked in females than males and produced some necrosis at the highest dose. There were no other adverse findings noted.

Executive summary:

In a well conducted study designed to assess the sub-chronic and reproductive toxicity of 2 -(2 -butoxyethoxy)ethanol to rats, the test substance was administered by the dermal route for 13 weeks to the maximum practical concentration attainable of 2ml/kg. The only effect of note was dermal irritation at the site of repeated application which occured at all doses, albeit very slight at the low dose and only in males at towards the end of the study. Irritancy was more marked in females than males and produced some necrosis at the highest dose. There were no other adverse findings noted.