4-ethylphenol

Acute Toxicity: oral

Administrative data

Endpoint:

acute toxicity: oral

Type of information:

experimental study

Adequacy of study:

key study

Study period:

February 1999

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

comparable to guideline study

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

1999

Materials and methods

Test guideline

Qualifier:

equivalent or similar to guideline

Guideline:

OECD Guideline 401 (Acute Oral Toxicity)

GLP compliance:

not specified

Test type:

standard acute method

Limit test:

yes

Test material

Test material information

Constituent 1

Reference substance name:

4-ethylphenol

EC Number:

204-598-6

EC Name:

4-ethylphenol

Cas Number:

123-07-9

Molecular formula:

C8H10O

IUPAC Name:

4-ethylphenol

Test material form:

solid: crystalline

Details on test material:

The test compound 4-ethylphenol (referred to as 4-EP, CAS No. 123-07-9, purity: 98.3 %) is a white crystalline compound. 4-EP was filled in light-protected airtight containers and stored in a cool and dark place (measured range 4 - 10 °C). As test material sample about 1 g of the above mentioned lot was collected and stored in a specimen preservation room of the testing facility.

Test animals

Species:

rat

Strain:

other: SPF Crj:CD (SD) IGS

Sex:

male/female

Details on test animals or test system and environmental conditions:

ANIMALS
SPF Crj:CD (SD) IGS rats from the Atsugi Breeding Center of Charles River Laboratories Japan, Inc., were used for the testing. 13 rats of each sex with an age of 4 weeks were purchased on 10 February 1999. The weight range of the animals at the time of arrival was 73 - 81 g for the males and 71 - 79 for the females.
After receiving, the general appearance of each individual was observed once a day for 7 days. In addition, their weight was determined twice during this period. For the duration of quarantine and acclimatization no abnormalities were observed in the animals.
After the end quarantine and acclimatization, 10 healthy animals of each sex with an age of 5 weeks were selected and provided for the tests. They were divided by the stratification random sampling method into groups with the same average weight based on the weight on the day of the end quarantine and acclimatization (the day before administration). The weight range for the animals was 132 - 139 g for the males and 116 -122 g for the females, and was less than +/- 20 % of the average weight (males 135.6 g, females 119.8 g). The animals excluded from the selection were not used for the test.
The animals were marked with an oil-based marker on the tail for individual identification. Before separation into groups, the breeding cages were marked on the front with labels in a different color for each sex, on which the test number and the animal numbers had been specified. After separation into groups they were marked on the front with labels in different color for each sex, on which the test number, the test group and the animal number had been specified.

HOUSING
During the quarantine and acclimatization period 3 to 5 animals separated by sex were accommodated in cages made from bracket-type metal with a metallic wire mesh bottom (260W x 380D x 180H, mm), after separation into groups 1 animal was accommodated. The cage and the feeder were cleaned once at the time of separation into groups and the tray was exchanged twice a week for sterilization. The automatic water supply equipment was drained once a week. The animal breeding room was cleaned a disinfected in a frequency of once a day. For disinfection chlorinebased and iodine-based disinfectants were used alternating weekly.
Solid feed CRF-1, made by Oriental Yeast Co., Ltd., irradiated with gamma rays, was provided in a metallic feed supplier ad libitum. The presence or absence of contaminating material, which may have an adverse effect on the test, or of microorganisms was analyzed in the used lots of the feed (980904 and 981209). The analysis of contaminating material was carried out in the Japan Food Research Laboratories and the bacteriological testing was carried out by the feed manufacturer. The items to be analyzed and the acceptable values were in compliance with the standard operating procedures of the Safety Research Institute for Chemical Compounds Co., Ltd. As a result of the analysis no values exceeding the acceptable values were observed.
Sapporo tap water was provided ad libitum using automatic water supply equipment. Samples were taken on 12 January 1999 and 6 April 1999 and analyzed for the presence or absence of contaminating material which may have an adverse effect on the test. The analysis was carried out by Hygiene Co., Ltd. Japan. The items to be analyzed and the acceptable values were in compliance with the standard operating procedures of the Safety Research Institute for Chemical Compounds (Co., Ltd.). As a result of the analysis, no values exceeding the acceptable values were observed

ENVIRONMENTAL CONDITIONS
The animals were raised in an animal breeding room (room No. 310) with a temperature of 23 +/- 3 °C (measured range 21 - 23 °C), a humidity of 55 +/- 10 % (measured range 50 - 57 %), an air change rate of 10 - 15 times per hour and an illumination time of 12 hours (artificial light switched on 8 a.m. and turned off 8 p.m.). The temperature and the humidity of the breeding room were monitored every day and a deviation of the set range, which might have an influence on the health of the animals, was not observed.

Administration / exposure

Route of administration:

oral: gavage

Vehicle:

olive oil

Remarks:

Japanese Pharmacopeia olive oil (Lot number: 807089, Yakuhan Pharmaceutical Co., Ltd.)

Details on oral exposure:

The test compound was administered forcibly according to the OECD guidelines for testing methods (401) after an overnight fast (about 16 - 17 hours) orally once between 9.00 and 10.00 AM using a stomach tube. About 4 hours after administration, the feeding was continued.
The dose capacity was set to 10 mL/kg and the individual administration volume was calculated on the basis of the bodyweight on the day of administration.

Doses:

2000 mg/kg bw

No. of animals per sex per dose:

5

Control animals:

yes

Remarks:

vehicle control

Details on study design:

The dosage of the test material was set on the basis of the results of a preliminary test (test number SR-9882). In the preliminary test doses of 75, 150, 300, 600, 1200, 2000 and 3000 mg/kg were administered once orally to one group of 3 SD-rats of each sex.
Based on the results of the preliminary test, as defined in the OECD guidelines for testing methods (401), the limit of the dose for males and females as dosage in this test was set to 2000 mg/kg. In addition, a control group was established to which only olive oil serving as solvent was administered by the same method. From one day after administration until autopsy on Day 14 they were observed once a day.

Statistics:

The body weight, the body weight increment and the body weight growth rate were determined by the Bartlett assay method, and their homoscedasticity was examined. In case of equal dispersion, analysis was carried out by the method of one-way analysis of variance, and in case of non-equivalent dispersion by the Kruskal-Wallis assay method. If significant differences were seen in the results of the method of oneway analysis of variance, a comparison with the control group was carried out by the Dunnett assay method. If significant differences were seen in the results of the analysis by the Kruskal-Wallis method, a comparison with the control group was carried out by the U-assay method of Mann-Whitney.

In addition, for the approval of the comparison between the groups administered with the test material and the control group, the average and standard deviation of the groups was used and a risk rate of less than 5 % was considered to be statistically significant.

Results and discussion

Preliminary study:

- 3000 mg/kg: As a change in the general appearance a staggering gait appeared in two examples of male and three examples of female rats from several minutes to 10 minutes after administration, and a prone or lateral position was observed. In the same group two male and three female rats died until one day after administration.

- 2000 mg/kg: A staggering gait or rapid breathing appeared in one male and two female rats from several minutes to 30 minutes after administration, successively a prone or lateral position continuing 1 - 3 hours was observed but no dead rats were found.

- 1200 mg/kg: A staggering gait appeared only in one male rat from about 10 to 30 minutes after administration.

In the other groups no abnormalities were seen.

Effect levels

Key result

Sex:

male/female

Dose descriptor:

LD50

Effect level:

> 2 000 mg/kg bw

Based on:

test mat.

Mortality:

none

Clinical signs:

other: A staggering gait appeared in three male and two female rats from about 10 minutes to 20 minutes after administration, successively a prone or lateral position was observed in two male and one female rats, and rapid breathing in two male and one female ra

Gross pathology:

A cyst of the kidney was seen in one male of the control group. In the 2000 mg/kg administered group, no abnormalities were observed in males and females.

Other findings:

None

Any other information on results incl. tables

As a part of an investigation into the safety of chemical substances in the OECD’s Existing Chemicals Database, a dose of 0 mg/kg (control group) and 2000 mg/kg of 4-ethylphenol was administered orally to groups of 5 species of each male and female Crj:CD (SD) IGS rats per group in a single dose to examine its acute toxicity.

As a result, a staggering gait starting 10 minutes after administration, successively a prone or lateral position and rapid breathing of the male and female animals were observed as poisoning symptoms in the 2000 mg/kg administered group. It was considered that the expression of these symptoms was caused by direct action of the test material but since all symptoms receded two hours after administration, they seem to be a temporary change. Afterwards until the ending day of the observation period 14 days after administration no abnormality was observed.

The bodyweight of the males and females was significantly low one day and three days after administration compared to the control group. The value for the males was significantly low during the observation period from 5 days after administration onwards, and also the body weight increment and the body weight growth rate was significantly low.

On the other hand, no significant difference was found for the females from 5 days up to 14 days after administration but a difference in the recovery condition of males and females was observed. However, in the autopsy 14 days after administration no abnormalities caused by the administration of the test material were found in both males and females.

Accordingly, if 2000 mg/kg of 4-ethylphenol is administered orally in a single dose temporarily a staggering gait, a prone or lateral position and rapid breathing occurred as sudden poisoning symptoms but did not result in the death of the animals, therefore the LD50 value was estimated to be more than 2000 mg/kg for both males and females.

Applicant's summary and conclusion

Interpretation of results:

GHS criteria not met

Conclusions:

Under the conditions of this study, the LD50 of 4-ethylphenol is considered to be > 2000 mg/kg bw.

Executive summary:

4-Ethylphenol was administered orally in a dose of 0 mg/kg (control group) and 2,000 mg/kg to groups of 5 of each male and female Crj:CD (SD) IGS rats per 1 group in a single dose to examine its acute toxicity.

The following results were obtained.

1. As no male or female rat died, it was estimated that the LD50-value is above 2,000 mg/kg for both males and females.

2. In the general appearance, 10 minutes after administration a staggering gait and successively a prone or lateral position and rapid breathing was observed in male and female animals of the 2,000 mg/kg administered group. These symptoms receded until two hours after the end of administration and no abnormalities were found later until the end of the observation period of 14 days.

3. The average body weight of the males of the 2,000 mg/kg administered group had a significantly low value compared to the control group during the observation period from 1 day to 14 days after administration and the weight increment and the weight growth rate were significantly low, too. On the other hand, the values of the females were significantly lower compared to the control group 1 day and 3 days after administration but no significant difference was observed from 5 days up to 14 days after administration.

4. No abnormalities caused by the administered test compound were found by the autopsy 14 days after administration in both male and female rats.