2-(2-naphthyloxy)ethanol

Repeated dose toxicity: dermal

Administrative data

Endpoint:

sub-chronic toxicity: dermal

Type of information:

experimental study

Adequacy of study:

key study

Study period:

Published May 3rd 1991

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: Study comparable to guideline study, performed on a suitable analogue substance.

Data source

Reference

Reference Type:

publication

Title:

Unnamed

Year:

1991

Materials and methods

Test guideline

Qualifier:

no guideline followed

Principles of method if other than guideline:

No guideline stated in the publication. Study conducted equivalent or similar to OECD Guideline 411 (Subchronic Dermal Toxicity: 90-Day Study).

GLP compliance:

yes

Limit test:

no

Test material

Test material information

Constituent 1

Reference substance name:

2-phenoxyethanol

EC Number:

204-589-7

EC Name:

2-phenoxyethanol

Cas Number:

122-99-6

Molecular formula:

C8H10O2

IUPAC Name:

2-phenoxyethanol

Details on test material:

- Name of test material (as cited in study report): Ethylene Glycol Phenyl Ether (EGPE)
- Analytical purity: >99.9%

Test animals

Species:

rabbit

Strain:

New Zealand White

Sex:

male/female

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Source: Hazleton-Dutchland, Denver, PA.
- Age at study initiation: approx. 5 months
- Weight at study initiation: Not stated.
- Fasting period before study: Not stated.
- Housing: Individually
- Diet: ad libitum (Certified Laboratory Rabbit Chow, Ralston Purina Co., St. Louis, MO)
- Water: ad libitum
- Acclimation period: minumum of 3 weeks


ENVIRONMENTAL CONDITIONS
- Temperature (°C): approx. 22
- Humidity (%): 50%
- Photoperiod (hrs dark / hrs light): 12/12

Administration / exposure

Type of coverage:

occlusive

Vehicle:

unchanged (no vehicle)

Details on exposure:

EPGE was uniformly spread over clipped area (approximately 10x15 cm) using a syringe and blunt tipped needle. The application site was reclipped as required during the study to keep it free of hair. An occlusive wrap of absorbent gauze and non absorbant cotton was placed over the application area and was held in place using an elastic jacket. The wraps and jackets were removed approximately 6 hours after each dose was applied. The backs of the rabbits were not wiped since no appreciable amount of test material was apparent at the site of application after 6 hour exposure period.

Dosing volumes were approximately 0.05 to 0.50 ml/kg/day and was adjusted weekly based upon body weight.

Analytical verification of doses or concentrations:

not specified

Duration of treatment / exposure:

13 weeks

Frequency of treatment:

6 hours/day, 5 days/week for thirteen weeks.

Doses / concentrations

Remarks:

Doses / Concentrations:
0, 50, 150, 500 mg/kg bw/day
Basis:
nominal per unit body weight

No. of animals per sex per dose:

10

Control animals:

yes, sham-exposed

Details on study design:

- Dose selection rationale: The top dose level of the study (500 mg/kg/day) was selected based on the results of previous studies, in which hemolytic effects/mortality was observed following 12 consecutive daily dermal doses of 600 mg/kg/day.

- Randomization of test animals to treatment groups was performed using a computer generated randomization scheme designed to produce groups with equivalent mean body weight and variance. All aminals were identified by means of a uniquely numbered metal ear tag.

Examinations

Observations and examinations performed and frequency:

DETAILED CLINICAL OBSERVATIONS: Yes

All animals were observed daily throughout the test period for indications of toxicity. Animals found dead or moribund or surviving the treatment period were submitted for a complete gross pathological examination by a veterinary pathologist.

DERMAL IRRITATION (if dermal study): Yes

The condition of the skin at the site of test material application was assessed and recorded prior to dosing for the first two weeks and approximately weekly thereafter using the laboratory's modification of the draize system.

BODY WEIGHT: Yes

All rabbits were weighed prior to the first exposure and weekly thereafter.

FOOD CONSUMPTION: No data.


WATER CONSUMPTION: No data.


OPHTHALMOSCOPIC EXAMINATION: No data.


HAEMATOLOGY: Yes

Blood samples (approximately 7 mL) for hematology and clinical chemistry determinations were obtained from the auricular artery of all rabbits approximately 1 week prior to dosing and after 4 and 13 weeks of treatment. Samples for hematological determinations were collected using vacuum tubes and mixed with potassium EDTA anticoagulant. RBC, WBC, and PLAT counts, HGB concentration, PCV, and RBC indices (MCV, MCH, MCHC) were determined on all samples. Differntial leukocyte and reticulocyte (RETICS) counts and RBC morphological determinations were condicted on samples from all control and high dose rabbits by direct examination of stained smears after 13 weeks of treatment only.

CLINICAL CHEMISTRY: Yes

Blood samples for clinical chemistry determinations were allowed to clot at 0-5 degrees C and serum was harvested by centrifugation. Alanine aminotransferase activity, aspartate aminotransferase activity, glucose, total protein, albumin, globulin and total bilirubin were determined on all samples.

URINALYSIS: No data.

Sacrifice and pathology:

GROSS PATHOLOGY: Yes

On the day following the last dermal application of EGPE, each rabbit was euthanatized with CO2, weighed and examined for gross pathological alterations. Brain. heart, liver, kidneys, and testes were weighed and relative organ weights (g/l00 g body weight) were calculated.

HISTOPATHOLOGY: Yes

A representative sample of all organ systems and tissues were collected from each rabbit at necropsy and preserved in neutral, phosphate-buffered 10% formalin. All tissues collected from control and high dose animals were processed by conventional histologic techniques, stained with
haematoxylin and eosin and evaluated by light microscopy.

Statistics:

Body weight, organ weight and appropriate haematology and clinical chemistry data were evaluated by Bartlett’s test (a = 0.01) for the equality of variances. Based upon the outcome of Bartlett’s test, a parametric or nonparametric analysis of variance (ANOVA) was conducted followed by Dunnett’s test or the Wilcoxon rank-sum test with Bonferroni’s correction (a = 0.10) if the ANOVA was significant. The nominal level of significance used for comparing results obtained from control and treated groups was 0.05. Statistical outliers were identified by a sequential outlier test but were not excluded from analysis.

Results and discussion

Results of examinations

Clinical signs:

no effects observed

Description (incidence and severity):

No overt signs of systemic toxicity (including hemoglobinuria) or early mortality of treated rabbits were noted over the 13 week period.

Dermal irritation:

effects observed, treatment-related

Description (incidence and severity):

See Details on Results below.

Mortality:

no mortality observed

Description (incidence):

No overt signs of systemic toxicity (including hemoglobinuria) or early mortality of treated rabbits were noted over the 13 week period.

Body weight and weight changes:

no effects observed

Description (incidence and severity):

No treatment related effects upon body weight.

Food consumption and compound intake (if feeding study):

not specified

Food efficiency:

not specified

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

not specified

Ophthalmological findings:

not specified

Haematological findings:

no effects observed

Description (incidence and severity):

No treatment related effects on haematologic parameters.

Clinical biochemistry findings:

no effects observed

Description (incidence and severity):

No treatment related effects on clinical chemistry parameters.

Urinalysis findings:

not specified

Behaviour (functional findings):

not specified

Organ weight findings including organ / body weight ratios:

no effects observed

Description (incidence and severity):

No treatment related effects on organ weights.

Gross pathological findings:

no effects observed

Description (incidence and severity):

No gross changes attributed to EGPE.

Histopathological findings: non-neoplastic:

no effects observed

Description (incidence and severity):

No microscopic changes attributed to EGPE.

Histopathological findings: neoplastic:

no effects observed

Description (incidence and severity):

No microscopic changes attributed to EGPE.

Details on results:

The only potentially treatment related effect was the sporadic observation of erythema and very slight-to-slight scaling of the skin at the site of test material application in male and female rabbits exposed to 500 mg EGPE/kg/day. However, as these effects were not associated with gross or histologic changes in the skin they were not considered to be of toxicologic significance.

Effect levels

1

Dose descriptor:

NOAEL

Effect level:

500 mg/kg bw/day (nominal)

Based on:

test mat.

Sex:

male/female

Basis for effect level:

other: Absence of significant toxicological effects at all exposure levels.

2

Dose descriptor:

LOAEL

Effect level:

> 500 mg/kg bw/day (nominal)

Based on:

test mat.

Sex:

male/female

Basis for effect level:

other: Absence of significant toxicological effects at all exposure levels.

Target system / organ toxicity

Critical effects observed:

not specified

Applicant's summary and conclusion

Conclusions:

Dermal administration of up to 500 mg/kg bw/day EGPE (the highest dose tested) for 90 days had no effect in rabbits other than sporadic observation of erythema and very slight to slight scaling of the skin at the test site. However as these effects were not associated with gross or histological changes in the skin they were not considered to be of toxicological significance. The NOAEL was therefore concluded to be 500 mg/kg bw/day.

Executive summary:

Dermal administration of up to 500 mg/kg bw/day (the highest dose tested) of ethylene glycol phenyl ether (2-phenoxyethanol) for 90 days had no effect in rabbits other than sporadic observation of erythema and very slight to slight scaling of the skin at the test site. As these effects were not associated with gross or histological changes in the skin they were not considered to be of toxicological significance.

In conclusion, no systemic toxicity was seen when rabbits were dermally exposed to 2-phenoxyethanol for 13 weeks at doses of up to 500 mg/kg bw/day, under conditions reflective of potential human occupational exposure.

The data presented for the analogue substance, 2-phenoxyethanol (EC 204-589-7), is considered appropriate for read-across to EC 202-228-8 and for use in the generation of DNELs and concluding on classification. The justification for the use of this read across is provided within IUCLID section 13.