Methyl 2-ethylhexanoate

Endpoint summary

Description of key information

Oral: LD50= > 2000 mg/kg bw, female rat, OECD 425, Product Safety Laboratories 2003

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:

2003

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: Guideline study performed under GLP.

Qualifier:

according to guideline

Guideline:

OECD Guideline 425 (Acute Oral Toxicity: Up-and-Down Procedure)

Deviations:

no

Qualifier:

according to guideline

Guideline:

EPA OPPTS 870.1100 (Acute Oral Toxicity)

Deviations:

no

GLP compliance:

yes

Test type:

up-and-down procedure

Limit test:

yes

Species:

rat

Strain:

Sprague-Dawley

Sex:

female

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Source: Recognised animal supplier
- Age at study initiation: 9 weeks
- Weight at study initiation: Females 164 - 185g
- Fasting period before study: Fasted overnight
- Housing: Individually housed suspended stainless steel caging with mesh floors consistent with Guide for the Care and Use of Laboratory Animals DHEW (NIH).
- Diet (e.g. ad libitum): Purina Rodent Chow #5012
- Water (e.g. ad libitum): flitered tap water ad libitum
- Acclimation period: 6 - 10 days

ENVIRONMENTAL CONDITIONS
- Temperature (°C): 18 - 22
- Humidity (%): Not reported
- Air changes (per hr): Not reported
- Photoperiod: 12 hours light/12 hours dark

IN-LIFE DATES: 08/10/2003 To: 28/10/2003

Route of administration:

oral: gavage

Vehicle:

unchanged (no vehicle)

Details on oral exposure:

MAXIMUM DOSE VOLUME APPLIED: Individual doses were calculated based on the initial body weights, taking into account the specific
gravity of the test substance (0.866 g/ml) determined by the laboratory. The maximum dose volume applied was 0.43 ml test substance.

Doses:

2000 mg/kg; dosed sequentially in a limit test based on absence of mortality at the limit dose.

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: The animals were observed for mortality, signs of gross toxicity, and behavioral changes during the
first several hours post-dosing and at least once daily thereafter for 14 days after dosing.
- Necropsy of survivors performed: yes
- Other examinations performed: Individual body weights of the animals were recorded prior to test substance administration (initial)
and again on Days 7 and 14 (termination) after dosing.

Statistics:

No statistical analysis was used.

Sex:

male/female

Dose descriptor:

LD50

Effect level:

> 2 000 mg/kg bw

Based on:

test mat.

Mortality:

No deaths occurred during the study.

Clinical signs:

Clinical observations noted for two animals included hypoactivity, piloerection, and reduced fecal volume. However, the affected animals recovered by Day 2 and, along with the other animals, appeared active and healthy for the remainder of the study.

Body weight:

All animals gained body weight during the course of the study.

Gross pathology:

No gross abnormalities were noted on necropsy.

Interpretation of results:

not classified

Remarks:

Migrated information Criteria used for interpretation of results: EU

Conclusions:

The acute oral median lethal dose (LD50) in the female rat was greater than 2000 mg/kg body weight.

Executive summary:

The study was performed to OECD 425 and US EPA OPPTS 870.1100 in accordance with GLP to assess the acute oral toxicity of the test material in the female Sprague-Dawley rat. The test material was administered orally, after fasting overnight. An initial dose of 2,000 mg/kg was administered to one healthy female rat by oral gavage. Due to the absence of mortality in this animal, four additional females received the same dose level. Since these animals survived, no additional animals were tested. Females were selected for the test because they are frequently more sensitive to the toxicity of test compounds than males. All animals were observed for mortality, signs of gross toxicity, and behavioural changes at least once daily for 14 days after dosing. Body weights were recorded prior to administration and again on Days 7 and 14 (termination) after dosing. There was no mortalities and body weights increased following administration, clinical observations noted for two animals included hypoactivity, piloerection, and reduced fecal volume. However, the affected animals recovered by Day 2 and, along with the other animals, appeared active and healthy for the remainder of the study. No gross abnormalities were noted at necropsy. Under the conditions of this study, the acute oral LD50 of the test substance is greater than 2,000 milligrams of the test substance per kilogram of body weight in female rats.

Endpoint conclusion

Endpoint conclusion:

no adverse effect observed

Quality of whole database:

The available information as a whole meets the tonnage driven information requirements of REACH.

Acute toxicity: via inhalation route

Endpoint conclusion

Endpoint conclusion:

no study available

Acute toxicity: via dermal route

Endpoint conclusion

Endpoint conclusion:

no study available

Additional information

Key Study – OECD 425 (2003): The study was performed to OECD 425 and US EPA OPPTS 870.1100 in accordance with GLP to assess the acute oral toxicity of the test material in the female Sprague-Dawley rat. The test material was administered orally, after fasting overnight. An initial dose of 2,000 mg/kg was administered to one healthy female rat by oral gavage. Due to the absence of mortality in this animal, four additional females received the same dose level. Since these animals survived, no additional animals were tested. Females were selected for the test because they are frequently more sensitive to the toxicity of test compounds than males. There was no mortalities and body weights increased following administration, clinical observations noted for two animals included hypoactivity, piloerection, and reduced fecal volume. However, the affected animals recovered by Day 2 and, along with the other animals, appeared active and healthy for the remainder of the study. No gross abnormalities were noted at necropsy. Under the conditions of this study, the acute oral LD50 of the test substance is greater than 2,000 milligrams of the test substance per kilogram of body weight in female rats.

 

Disregarded Study – eq. OECD 401 (1989): The study was performed to assess the acute oral toxicity potential of the test substance to Sprague Dawley derived rats (Crl: CD(SD)BR strain, (VAF+)). The study was performed to GLP and followed a method similar to OECD 401 method. Following overnight fasting, the test material was administered as a single oral dose to a group of five male and five female rats, by peroral injection, at a dose level of 2000 mg/kg bodyweight. All animals were observed for a fourteen day period for any signs of toxicity or other effects of treatment, after which surviving animals were killed and subjected to gross necropsy. As deaths occurred at this dose level, the study was repeated using a dose level of 500mg/kg. The limit test at 2000mg/kg produced death in one male and three females. Few symptoms were recorded and no significant abnormalities were noted at necropsy. In the symptoms, seen in recovered limit test at 500 mg/kg bw there were no mortalities but some including piloerection, salivation and hypoactivity were the male rats after dosing. All animals had apparently recovered by Day 2 and no abnormalities were noted at necropsy. Under the conditions of this study the LD50 was determined to be between >500 - <2000 mg/kg.

 

The applicant assesses this study by expert judgement and indicates: Whilst the study is relevant and reliably demonstrating an absence of toxicity at < 500 mg/kg bw levels; due to deficiencies: apparent acclimatisation, group housing and environmental conditions and inconsistencies in the clinical signs/necropsy relative to observed mortality at 2000 mg/kg bw within this study; conclusions at this dose level should be only considered as reliable with restrictions. Increased morbidity may not have been substance related since the subsequent second limit test (at 500 mg/kg bw) no mortality occurred but would have allowed for an increase in acclimatisation time prior to initiation; clinical signs were non-specific and confined to males only and may not have been substance related since they were not seen in males in the higher dose (2000 mg/kg bw) or females (typically more sensitive sex) at either dose level. Body weight gains were observed in all surviving males/females.

Justification for selection of acute toxicity – oral endpoint
Two in vivo studies available: 1. OECD 425: Klimisch 1 under GLP and; 2. eq. to OECD 401 under GLP: Klimisch 4. Selected study is the study of higher reliability. The selected study does not have the lowest dose descriptor however this is scientifically justified on the following basis:
1. Study 2 deviated from guideline in the environmental conditions employed and utilised group housing; acclimatisation prior to the study initiation may not have been under the conditions employed in the test. The age of the animals was not fully defined and may have impacted the study if group-housed. All animals gained body weight during the course of the study. Clinical signs were not consistent or severe at the highest limit dose (hypoactivity and hunched posture isolated to one animal). Necropsy had no significant findings. Increased morbidity may not have been substance related since the second limit test (at 500 mg/kg bw) would have allowed for an increase in acclimatisation time prior to initiation and no mortality occurred; clinical signs were confined to males only and may not have been substance related since they were not seen in males in the higher dose. The study demonstrates no significant toxicity at < 500 mg/kg bw. The study by expert judgement did not conclusively demonstrate morbidity and mortality was test item clinical or systemic toxicity related at 2000 mg/kg bw.
2. Study 1 in female rats only did not deviate from guideline: acclimatisation was post individual-housing and exceeded 6 days. All animals gained body weight during the course of the study. Clinical signs were reversible, isolated to two animals and not severe (hypoactivity, piloerection, and reduced fecal volume). Necropsy did not produce any significant findings.
Study 1 findings are conclusive and consistent with other available in vivo data available to the applicant. See ‘justification for classification or non-classification’ for more details.

Justification for classification or non-classification

The substance does not meet classification criteria under EU Directive 67/548/EEC for acute toxicity.

The substance does not meet classification criteria under Regulation (EC) No 1272/2008 for acute toxicity.

 

The substance does not meet classification criteria under Regulation (EC) No 1272/2008: for Specific Target Organ Toxicity - Single Exposure.

 

The selected key study (OECD 425, 2003) findings are conclusive and consistent with other in vivo data available to the applicant. In multiple species for observed absence of severe clinical and systemic toxicity in other endpoints. For example: acute dermal toxicity in rabbit at GHS category 5 levels (5000 mg/kg bw) showed no clinical or systemic necropsy abnormalities and skin sensitisation in guinea pig maximisation tests by intradermal injection; all animals gained body weight. Where single mortality occurred it was deemed not substance related. Overall, the weight of evidence (for Acute Toxicity: oral route) indicates that the substance is not classified under Regulation (EC) 1272/2008 criteria. The disregarded study (OECD 401, 1989) had specific issues that by expert judgement appear to have resulted in non-substance mortalities at category 4 levels (< 2000mg/kg bw); these issues include group housing, potential incomplete acclimatisation and inconsistencies in clinical signs between sex-doses; gross necropsy, bodyweight increases and mortality at 2000 mg/kg bw and subsequent 500 mg/kg bw limit tests.

 

Evaluation of available in vivo studies only; the selected key study and the disregarded study support the conclusion that the substance does not meet the criteria for STO – SE under Regulation (EC) 1272/2008. Necropsy did not indicate abnormalities at guidance levels. Increased morbidity in the disregarded study is not conclusively substance related and was not observed in the key study. In all relevant studies body weight gains were observed. Clinical signs were transient and fully reversible and not supporting of any category of classification.