Ethoxyquin

Acute Toxicity: oral

Administrative data

Endpoint:

acute toxicity: oral

Type of information:

experimental study

Adequacy of study:

key study

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

data from handbook or collection of data

Remarks:

Peer-reviewed assessment report (attached in section 13)

Data source

Reference

Reference Type:

publication

Title:

Unnamed

Year:

2007

Report date:

2007

Materials and methods

Test guideline

Test guideline 1

Qualifier:

according to guideline

Guideline:

EPA OPP 81-1 (Acute Oral Toxicity)

Version / remarks:

US EPA FIFRA Guideline §81-1

Deviations:

yes

Remarks:

Purity of the test compound was not determined by the laboratory prior to conduct of the test

Test guideline 2

Qualifier:

equivalent or similar to guideline

Guideline:

OECD Guideline 401 (Acute Oral Toxicity)

Deviations:

not applicable

GLP compliance:

yes

Remarks:

self-certified to US EPA regulations at 40 CFR Parts 160 and 792

Test type:

standard acute method

Limit test:

no

Test material

Test material information

Constituent 1

Reference substance name:

Ethoxyquin

EC Number:

202-075-7

EC Name:

Ethoxyquin

Cas Number:

91-53-2

Molecular formula:

C14H19NO

IUPAC Name:

ethoxyquin

Details on test material:

Chemical name
IUPAC: 6-ethoxy-2,2,4-trimethyl-1,2-dihydroquinoline
CAS: 6-ethoxy-1,2-dihydro-2,2,4-trimethylquinoline

Specific details on test material used for the study:

clear reddish brown liquid

Test animals

Species:

rat

Strain:

other: albino rats (Crl:CD®BR)

Sex:

male/female

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Source: Charles River Breeding Laboratories, Inc. Portage MI USA
- Age at study initiation: young

Administration / exposure

Route of administration:

oral: gavage

Vehicle:

unchanged (no vehicle)

Details on oral exposure:

MAXIMUM DOSE VOLUME APPLIED: 2.51 mL/kg

Doses:

1500, 1950 and 2535 mg/kg bw

No. of animals per sex per dose:

5/sex/dose

Control animals:

other: not required

Details on study design:

- Duration of observation period following administration: 14 days
- Necropsy of survivors performed: yes
- Other examinations performed: clinical signs

Results and discussion

Effect levels

Effect levels 1

Sex:

male/female

Dose descriptor:

LD50

Effect level:

1 726 mg/kg bw

Based on:

test mat.

Effect levels 2

Key result

Sex:

female

Dose descriptor:

LD50

Effect level:

1 675 mg/kg bw

Based on:

test mat.

Effect levels 3

Sex:

male

Dose descriptor:

LD50

Effect level:

1 779 mg/kg bw

Based on:

test mat.

Mortality:

All deaths occurred within 3 days of dosing. Mortality was 2/10, 9/10 and 8/10 for the 1500, 1950 and 2535 mg/kg bw groups, respectively.

Clinical signs:

Clinical signs included ataxia in 24 animals, hypoactivity (21 rats), ocular discharge (16 rats), urogenital staining, hypothermia (cool to touch, 13 rats), dried red material around the eye(s), forelimb(s), and/or nose, laboured respiration (11 rats), prostrate positioning (10 rats), abnormal excretion (5 rats), and dried yellow material around the mouth. With the exception of dried yellow urogenital staining noted for two rats, all surviving animals appeared normal by day 7 or earlier and throughout the remainder of the study.

Body weight:

There were no remarkable changes in body weights for all animals.

Gross pathology:

Histopathological changes indicated an irritant effect on the gastrointestinal tract. Three animals had an hemorrhagic thymus gland. Two rats had dark red lungs and red fluid contents in the urinary bladder. One animal had enlarged cervical lymph nodes, and one had opacity in the right eye. There were no other gross necropsy findings neither in the animals that survived to the scheduled euthanisation nor in those that were found dead.

Applicant's summary and conclusion

Interpretation of results:

Category 4 based on GHS criteria

Conclusions:

As information was provided via a peer-reviewed assessment report, it can be considered as sufficiently reliable to assess the acute toxicity of ethoxyquin towards rats. Based on mortality data, an oral LD50 of 1779 mg/kg bw was calculated for male rats, of 1675 mg/kg bw for females, and of 1726 mg/kg bw for both sexes combined. Since the LD50 was below the limit of 2000 mg/kg bw, ethoxyquin shall be classified as being harmful if swallowed, i.e. acute toxic cat. 4 acc. to Regulation 1272/2008.

Executive summary:

In an acute oral toxicity study (US EPA FIFRA Guideline §81-1, which is equivalent to OECD 401), groups of fasted, young adult albino rats (Crl:CD®BR)(5/sex/dose) were given a single oral dose ofneat ethoxyquinat doses of 1500, 1950 and 2535 mg/kg bw and observed for 14 days.

 

Oral LD₅₀Males = 1779 mg/kg bw

Females = 1675 mg/kg bw

Combined = 1726 mg/kg bw

 

Ethoxyquin is of slight Toxicity based on the LD₅₀ in females, and should be classified as acute toxic cat. 4.