Ethyl butyrate

Endpoint summary

Description of key information

Repeated oral toxicity

In a repeated oral toxicity study, 15 male and 15 female rats were administered 14.4 mg/kg bw of the given test chemical in diet for 12 weeks. No adverse effects were noted in the animals at the mentioned dose level. The No Observed Adverse Effect Level (NOAEL) was considered to be 14.4 mg/kg bw when male and female rats were exposed to the given test chemical for 12 weeks.

Repeated inhalative toxicity

Male and female Sprague-Dawley Crl:CD rats were exposed to Ethyl butyrate 1 hours/day, 5 days/week for 13 weeks.The comparison of rats exposed to similar concentrations of test (contains the target chemical) and reference cigarette smoke indicated no difference at any concentration Based on the data observed, it can be concluded that Ethyl butyrate did not exert toxicity upon repeated exposure by inhalation route.The NOAEL was estimated as 0.06 mg/L when male and female Sprague-Dawley rats were exposed to Ethyl butyrate by inhalation of cigarette smoke for 13 weeks.

Repeated dermal study;

The acute toxicity value for Ethyl butyrate (CAS no 105-54-4) (as provided in section 7.2.3) is >2000 mg/kg/body weight per day. Also, given the use of the chemical; repeated exposure by the dermal route is unlikely since the use of gloves is common practice in industries. Thus, it is expected that Ethyl butyrate shall not exhibit toxicity by dermal route upon repeated exposure. route. In addition, no experimental data available that suggests that Ethyl butyrate shall exhibit repeated dose toxicity by the dermal route. Hence this end point was considered for waiver.

Key value for chemical safety assessment

Toxic effect type:

dose-dependent

Repeated dose toxicity: via oral route - systemic effects

Link to relevant study records

Reference

Endpoint:

short-term repeated dose toxicity: oral

Type of information:

experimental study

Adequacy of study:

weight of evidence

Reliability:

4 (not assignable)

Rationale for reliability incl. deficiencies:

secondary literature

Justification for type of information:

The experimental data is presented in a WHO report.

Qualifier:

according to guideline

Guideline:

other: Refer below principle

Principles of method if other than guideline:

Short-term study of the given test chemical in rats was evaluated for its toxic nature upon repeated exposure.

GLP compliance:

not specified

Limit test:

no

Specific details on test material used for the study:

- Name of test material: Ethyl butyrate
- Molecular formula : C6H12O2
- Molecular weight : 116.16 g/mol
- Smiles notation : C(=O)(CCC)OCC
- InChl : 1S/C6H12O2/c1356(7)842/h35H2,12H3
- Substance Type: Organic
- Physical State: Liquid

Species:

rat

Strain:

not specified

Details on species / strain selection:

not specified

Sex:

male/female

Details on test animals or test system and environmental conditions:

not specified

Route of administration:

oral: feed

Details on route of administration:

not specified

Vehicle:

other: Diet

Details on oral exposure:

PREPARATION OF DOSING SOLUTIONS: The test substance was mixed with diet before feeding study was initiated.
VEHICLE
- Justification for use and choice of vehicle (if other than water): Diet
- Concentration in vehicle: 14.4 mg/kg bw

Analytical verification of doses or concentrations:

not specified

Details on analytical verification of doses or concentrations:

not specified

Duration of treatment / exposure:

12 weeks

Frequency of treatment:

Daily

Remarks:

Doses / Concentrations: 14.4 mg/kg bw

No. of animals per sex per dose:

15 males and 15 females

Control animals:

not specified

Details on study design:

not specified

Positive control:

not specified

Observations and examinations performed and frequency:

not specified

Sacrifice and pathology:

not specified

Other examinations:

not specified

Statistics:

not specified

Clinical signs:

not specified

Mortality:

not specified

Body weight and weight changes:

not specified

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:

not specified

Clinical biochemistry findings:

not specified

Urinalysis findings:

not specified

Behaviour (functional findings):

not specified

Immunological findings:

not specified

Organ weight findings including organ / body weight ratios:

not specified

Gross pathological findings:

not specified

Neuropathological findings:

not specified

Histopathological findings: non-neoplastic:

not specified

Histopathological findings: neoplastic:

not specified

Other effects:

not specified

Details on results:

No adverse effects were noted in test chemical-treated rats.

Dose descriptor:

NOAEL

Effect level:

14.4 other: mg/kg bw

Based on:

test mat.

Sex:

male/female

Basis for effect level:

other: No adverse effects were observed.

Remarks on result:

other: No adverse toxic effect were observed on treated rats

Critical effects observed:

not specified

Conclusions:

The given test chemical was observed for its toxic effect in rats. The No Observed Adverse Effect Level (NOAEL) was considered to be 14.4 mg/kg bw, when male and female rats were exposed to the given test chemical for 12 weeks.

Executive summary:

In a repeated oral toxicity study, 15 male and 15 female rats were administered 14.4 mg/kg bw of the given test chemical in diet for 12 weeks. No adverse effects were noted in the animals at the mentioned dose level. The No Observed Adverse Effect Level (NOAEL) was considered to be 14.4 mg/kg bw when male and female rats were exposed to the given test chemical for 12 weeks.

Endpoint conclusion

Endpoint conclusion:

no adverse effect observed

Dose descriptor:

NOAEL

1 000 mg/kg bw/day

Study duration:

chronic

Species:

rat

Quality of whole database:

The data is from publication

Repeated dose toxicity: inhalation - systemic effects

Link to relevant study records

Reference

Endpoint:

short-term repeated dose toxicity: inhalation

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

Justification for type of information:

Data is from peer reviewed publication

Qualifier:

according to guideline

Guideline:

other: Refer below principle

Principles of method if other than guideline:

Effects of the test chemical on the toxicity of mainstream cigarette smoke in rats.

GLP compliance:

not specified

Limit test:

no

Species:

rat

Strain:

Sprague-Dawley

Remarks:

Crl:CD

Sex:

male/female

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Source: Charles River Laboratories (Raleigh, NC)
- Age at study initiation: 6-7 weeks
- Weight at study initiation: No data available
- Fasting period before study: No data available
- Housing: During the 13-week exposure period, the animals were individual in stainless-steel cages on open racks, while the animals were housed indvidual in polycarbonate cages bedded with ALPHA-dri alpha cellulose bedding during the recovery period.
- Diet (e.g. ad libitum): No data available
- Water (e.g. ad libitum): No data available
- Acclimatization period: Approx. 13 days

ENVIRONMENTAL CONDITIONS
- Temperature (°C): No data available
- Humidity (%): No data available
- Air changes (per hr): No data available
- Photoperiod (hrs dark / hrs light): No data available

Route of administration:

inhalation

Type of inhalation exposure:

nose only

Vehicle:

air

Details on inhalation exposure:

GENERATION OF TEST ATMOSPHERE / CHAMBER DESCRIPTION
- Exposure apparatus: AMESA exposure units
- Method of holding animals in test chamber: No data available
- Source and rate of air: Air was drawn through the vacuum port by a peristaltic pump operating at a rate of approx. 1.05 l/min, creating a 2-s, 35 ml puff through each cigarette once each minute.
- Method of conditioning air: No data available
- System of generating particulates/aerosols: (RAM)-1 (MIE Inc., Bedford, MA)
- Temperature, humidity, pressure in air chamber: No data available
- Air flow rate: At a rate of approx. 1.05 l/min
- Air change rate: Air flows of at least No data available
- Method of particle size determination: No data available
- Treatment of exhaust air: No data available

TEST ATMOSPHERE
- Brief description of analytical method used: The WTPM:nicotine and CO:nicotine ratios were calculated for the exposure atmospheres. The concentration
of CO in the test and reference atmospheres was determined using Horiba PIR-2000 CO analyzers (Horiba Instruments, Inc., Irvine, CA), monitored by DOS-based computers. Particle size distribution of the smoke was measured using Mercer-style cascade impactors designed specifically for the size range of particles found in cigarette smoke.
- Samples taken from breathing zone: No data available

VEHICLE (if applicable)
- Justification for use and choice of vehicle: Air
- Composition of vehicle: No data available
- Type and concentration of dispersant aid (if powder): No data available
- Concentration of test material in vehicle: 0, 0.06, 0.2 or 0.8 mg/l
- Lot/batch no. of vehicle (if required): No data available
- Purity of vehicle: No data available

Analytical verification of doses or concentrations:

not specified

Duration of treatment / exposure:

26 weeks (including a recovery period of 13 weeks)

Frequency of treatment:

1 hour per day, 5 days per week

Remarks:

Doses /Concentrations: 0, 0.06, 0.2 or 0.8 mg/l

No. of animals per sex per dose:

Total: 240 rats
Control: 30 males, 30 females
0.06 mg/l: 30 males, 30 females
0.2 mg/l: 30 males, 30 females
0.8 mg/l: 30 males, 30 females

Control animals:

yes, sham-exposed

Details on study design:

Each group of 30 rats/sex was subdivided into 2 groups: 20 rats/sex scheduled for necropsy immediately after 13 wk of exposure (interim sacrifice) and up to 10 rats/sex scheduled for necropsy following 13 wk of recovery from smoke exposure (final sacrifice). Target smoke concentrations were 0.06, 0.2, or 0.8 mg WTPM/L for the test and reference cigarettes. An additional group of 30 rats/sex served as sham controls.

Positive control:

No data available

Observations and examinations performed and frequency:

CAGE SIDE OBSERVATIONS: Yes
- Time schedule: Twice daily
- Cage side observations included: Mortality and morbundity

DETAILED CLINICAL OBSERVATIONS: Yes
- Time schedule: IEvery 4 weeks

BODY WEIGHT: Yes
- Time schedule for examinations: During the randomization procedure, on exposure day 1, biweekly thereafter and at necropsy

FOOD CONSUMPTION AND COMPOUND INTAKE (if feeding study): No data available

FOOD EFFICIENCY: No data available

WATER CONSUMPTION AND COMPOUND INTAKE (if drinking water study): No data available

OPHTHALMOSCOPIC EXAMINATION: No data available

HAEMATOLOGY: Yes
- Time schedule for collection of blood: On the day of the 13-wk interim sacrifice
- Anaesthetic used for blood collection: Yes, approx. 70% carbon dioxide
- Animals fasted: No data available
- How many animals: On all rats included to be sacrificed on week 13
- Parameters examined: White blood cell (WBC) count, red blood cell (RBC) count, hemoglobin (Hb) concentration, volume of packed red cells (VPRC), the red cell indices (mean corpuscular volume [MCV], mean corpuscular hemoglobin [MCH], and mean corpuscular hemoglobin concentration [MCHC]), platelet count, and WBC differential counts. In addition, reticulocytes were stained.

CLINICAL CHEMISTRY: Yes
- Time schedule for collection of blood: On the day of the 13-wk interim sacrific
- Animals fasted: No data available
- How many animals: On all rats included to be sacrificed on week 13
- Parameters examined: Urea nitrogen (BUN), creatinine, glucose, total protein, albumin, aspartate aminotransferase (AST), alanine aminotransferase (ALT), gamma-glutamyl transpeptidase (GGT), sodium, potassium, chloride, calcium, phosphorus, total bilirubin, cholesterol, and triglycerides.

URINALYSIS: No data available

NEUROBEHAVIOURAL EXAMINATION: No data available

OTHER: Respiratory function measurements incl. tidal volume (TV), respiratory rate (RR) and minute volume (MV). In addition, the level of Carboxyhemoglobin and plasma nicotine in blood was measured during week 2 and 10.

Sacrifice and pathology:

GROSS PATHOLOGY: Yes
A complete necropsy was done on all 13-wk exposure groups and 13-wk recovery group animals. All abnormalities were recorded on the individual animal necropsy forms. Lungs, liver, kidneys, testes, adrenals, spleen, brain, and heart from all scheduled sacrifice animals were weighed. These organ weights and the body weights at necropsy were used to calculate organ:body weight ratios. In addition, organ:brain weight ratios were calculated.

HISTOPATHOLOGY: Yes
All tissues were fixed, sectioned and stained. Duplicate slides of nasal tissues, larynx, lung, and trachea were stained with periodic acid-Schiff/Alcian blue (PAS/AB) stains for evaluation of goblet cell populations. The lungs, nasal cavity (four sections), nasopharynx, larynx (three cross sections), trachea (three transverse sections), tracheobronchial lymph nodes, mediastinal (thymic) lymph nodes, heart, and all gross lesions were examined microscopically. The lungs were sectioned to present a maximal section of the main-stem bronchi. Three transverse laryngeal sections were prepared from the base of the epiglottis, the ventral pouch, and through the caudal larynx at the level of the vocal folds. In addition, sections of brain, adrenals, spleen, liver, kidneys, and gonads from animals in the sham control and the groups exposed to 0.8 mg/l of smoke from the test or reference cigarettes were examined microscopically. Exposure-related microscopic lesions were observed in the tissues from the rats exposed to 0.8 mg/l; target organs were examined microscopically in the lower concentration groups to ascertain a no-effect concentration.

Other examinations:

Evaluations of cell proliferations rates of respiratory-tract tissues was also performed, where cell proliferation rates were measured on respiratory tract tissues collected from 10 rats of each sex from each exposure group and the sham controls necropsied immediately after 13 wk of exposure, using a monoclonal antibody to 5-bromo-2'-deoxyuridine (BrdU). Tissues evaluated using the BrdU assay included the respiratory epithelium lining the median nasal septum and distal portions of maxillary and nasal turbinates, the transitional epithelium at the base of the epiglottis, the luminal epithelium dorsolateral to the ventral pouch, the luminal epithelium lining the cranial trachea, the luminal epithelium of the mainstem bronchi and adjacent bronchioles, and selected areas of alveolar epithelium.

Statistics:

Body weight, body weight gain, organ:body weight, and organ:brain weight ratios were statistically analyzed for each sex by exposure concentration group using the Xybion PATH/TOX system. Data homogeneity was determined by Bartlett’s test. Dunnett’s t -test was performed on homogeneous data to identify differences between each concentration group and the sham control group, and between corresponding concentrations of test and reference cigarette smoke-exposed groups. Nonhomogeneous data were analyzed using a modified t-test. Respiratory physiology, clinical pathology, COHb, and plasma nicotine data parameters were statistically evaluated using SAS software (Statistical Analysis System, SAS, Inc., Cary, NC). One-way analysis of variance (ANOVA) between exposure groups was first conducted, followed by Bartlett’s test for homogeneity of variance. A two-sided Dunnett’s multiple comparison test was employed to determine which exposure groups were different from the controls. An unpaired two-sided t -test was used to compare equivalent exposure groups between cigarette types. The statistical evaluation of incidence and severity of lesions was made using the Kolmogorov–Smirnov two-sample test. All treatment group means were compared to the sham control mean, and means of groups exposed to the test cigarette smoke were compared to the corresponding reference cigarette smoke-exposed group means. Cell proliferation data were compared statistically using Tukey’s studentized range test with SAS software.

Clinical signs:

no effects observed

Description (incidence and severity):

Exposure-related adverse clinical signs were absent. Clinical observations noted were minor in consequence and low in incidence.

Mortality:

no mortality observed

Description (incidence):

No significant mortality occurred.

Body weight and weight changes:

effects observed, treatment-related

Description (incidence and severity):

The only consistent statistical difference in body weight changes between the test and reference cigarette smoke-exposed groups in either study was the decreased mean body weight in males exposed to 0.8 mg/L of reference cigarette smoke during the exposure period of the first experiment. Mean body weights of smoke-exposed groups were similar to sham control weights during the recovery period.

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:

effects observed, treatment-related

Description (incidence and severity):

Whole-blood COHb levels were increased in a graded dose-response fashion as a function of exposure concentration for all test and reference cigarette smoke-exposed groups in both studies. In the second experiment, rats bled during exposure wk 2, there was a statistically significant decrease in COHb levels in both sexes exposed to 0.8 mg/L of test cigarette smoke and in females exposed to 0.2 mg/L of test cigarette smoke, compared to groups exposed to reference cigarette smoke. There were no other clear differences in whole-blood COHb levels between the test and reference cigarette groups at equivalent exposure levels in either study.

Clinical biochemistry findings:

effects observed, treatment-related

Description (incidence and severity):

Plasma nicotine levels increased in a graded dose-response fashion for test and reference males and female groups in both studies. In the second experiment, test female groups exposed to 0.8 mg/l had significantly lower plasma nicotine levels than the 0.8 mg/l reference females at both 2- and 10-wk sampling. Comparing males to females at all exposure levels for test and reference cigarettes, the females consistently had higher plasma nicotine levels in both studies.

Urinalysis findings:

not specified

Behaviour (functional findings):

not specified

Immunological findings:

not specified

Organ weight findings including organ / body weight ratios:

no effects observed

Description (incidence and severity):

Statistically significant differences in organ weights in groups of smoke-exposed rats were primarily low mean organ weights compared to their respective sham controls. There was no clear pattern of differences in any absolute or relative organ weight in smoke-exposed groups compared to sham controls, or in groups exposed to test versus reference cigarette smoke at either the interim sacrifice or the recovery sacrifices.

Gross pathological findings:

effects observed, treatment-related

Description (incidence and severity):

Few gross lesions were observed in either study, with no evidence of changes attributable to exposure to smoke from the test or the reference cigarettes. Exposure to smoke from reference or test cigarettes in both studies induced concentration-related proliferative, metaplastic, and inflammatory microscopic lesions in the respiratory tract after 13 wk of exposure.

Neuropathological findings:

not specified

Histopathological findings: non-neoplastic:

effects observed, treatment-related

Description (incidence and severity):

Hyperplasia of respiratory epithelium lining the anterior nasal cavity was present in all rats exposed to 0.8 mg/l in both studies. Areas most severely and most frequently affected were the distal portions of the nasal and maxillary turbinates in sections of nose just caudal to the incisor teeth. In affected rats, the epithelium in the distal turbinates was up to six cells thick. There was also a clear dose response in the severity of nasal respiratory epithelial hyperplasia, with severity ranging from minimal to moderate. Although not statistically significant compared to concurrent sham controls, the incidence of nasal goblet cell hyperplasia in male rats exposed to the 0.8-mg/L concentration of smoke from the reference cigarette or test cigarette in the first experiment were considered to be toxicologically significant. There was no clear difference in the incidence of goblet cell hyperplasia between groups exposed to similar concentrations of reference and test cigarette smoke in either study.
Exposure to smoke from the reference or test cigarette in both studies induced squamous metaplasia, hyperplasia, and hyperkeratosis of the transitional epithelium lining the base of the epiglottis and the epithelium lining the dorsal border of the ventral pouch and the adjacent laryngeal lumen. In affected smoke-exposed rats, the base of the epiglottis was covered by a stratified squamous epithelium up to eight cells thick with a variably keratinized surface layer and a distinct basal cell layer. There was a concentration-related increase in severity of squamous metaplasia and hyperplasia of epiglottis epithelium in rats exposed to test or reference cigarette smoke.
Comparison of incidence/severity of hyperkeratosis in the epiglottis between test and reference cigarette smoke-exposed groups indicated a statistically significant difference only in the 0.06-mg/L groups from study 1, in which females exposed to test cigarette smoke had a higher incidence/severity than females exposed to reference cigarette smoke.
An incidence (7/20) of goblet-cell hyperplasia in males exposed to the 0.8-mg/L concentration of smoke from the test cigarette in both studies, although not statistically significant, was considered to be toxicologically significant. Examination of tissue sections from rats necropsied at the end of the recovery period demonstrated nearly complete regression of nasal and tracheal lesions and a substantial decrease in the incidence and severity of smoke-induced lesions in the larynx and lungs in rats exposed to smoke from test or reference cigarettes in both studies. There was no statistically significant difference in the incidence or severity of respiratory-tract lesions between recovery group rats previously exposed to similar concentrations of test and reference cigarette smoke in either study.

Histopathological findings: neoplastic:

not specified

Other effects:

effects observed, treatment-related

Description (incidence and severity):

Reductions in RR and/or TV resulted in consistently lower MV in rats exposed to test or reference cigarette smoke compared to sham controls in both studies.

Dose descriptor:

NOAEL

Effect level:

0.06 mg/L air

Based on:

test mat.

Sex:

male/female

Basis for effect level:

body weight and weight gain

clinical biochemistry

gross pathology

haematology

histopathology: non-neoplastic

mortality

organ weights and organ / body weight ratios

Critical effects observed:

not specified

Conclusions:

The No observed adverse effect level (NOAEL) for the test chemical was considered to be 0.06 mg/L when male and female Sprague-Dawley Crl:CD rats were exposed by inhalation of cigarette smoke for 13 weeks.

Executive summary:

In a repeated-dose inhalation toxicity study, groups of 30 Sprague-Dawley rats of each sex were exposed to concentrations of 0.06, 0.2 or 0.8 mg/l WTPM of smoke from test cigarettes containing Ethyl butyrate(as flavoring agent) together by over 100 other additives. The animals were exposed by nose-only inhalation for 1 h/day, 5 day/week for 13 consecutive weeks or for 13 weeks of recovery from smoke exposure. In addition, groups of 30 rats/sex were exposed to same concentration of smoke from reference cigarettes, similar to the test cigarettes but without flavoring agent or to filtered air only (shame control). Test animals were observed for mortality and moribundity as well as for clinical signs. Individual body weights were recorded biweekly. Respiratory function measurements including Tidal volume (TV), respiratory rate (RR) and minute volume (MV) were measured in 4 rats/sex/group. Samples for blood test and blood clinical chemistry was also collected. At the end of the study, test animals were subject to gross pathological and histopathological examination. In addition, cell proliferation rates were measured on respiratory tract tissues collected from 10 rats of each sex from each exposure group. As seen by the results, no significant mortality occurred, and the exposure-related adverse clinical signs were absent. Minor clinical observations were noted in low incidence. The mean body weights were consistently decreased in male rats exposed to 0.8 mg/l of reference cigarette smoke and in males exposed to all 3 concentrations of test cigarette smoke compared to sham controls. The mean body-weights of all female smoke-exposed was comparable to shame control females through the study, and at the end of 13 week of recovery period, the mean body weight of all the test- and reference smoke-exposed animals were similar to sham control weights. Comparison of organ weights in rats indicated no consistent differences between smoke-exposed group and shame control or between the test and reference smoke-exposed groups at either the interim sacrifice or the recovery sacrifices. Reductions in Respiratory rate (RR) and/or Tidal volume (TV) resulted in consistently lower Minute volume (MV) in rats exposed to test or reference cigarette smoke compared to sham controls, as excepted. Also, there was no consistent difference in MV between groups of rats exposed to test and reference cigarette smoke.Exposure to smoke from both reference or test cigarettes induced increases in blood carboxyhemoglobin (COHb)) and plasma nicotine level, decreases in minute volume, differences in body or organ weights compared to air controls, and a concentration-related hyperplasia, squamous metaplasia, and inflammation in the respiratory tract. All these effects were greatly decreased or absent following the recovery period. Comparison of rats exposed to similar concentrations of test and reference cigarette smoke indicated no difference at any concentration. Thus, the results did not indicate any consistent differences in toxicological effects between smoke from cigarettes containing the flavoring or casing ingredients and reference cigarettes. Therefore, the NOAEL for the test chemical was considered to be 0.06 mg/L when male and female Sprague-Dawley rats were exposed by inhalation of cigarette smoke for 13 weeks.

Endpoint conclusion

Endpoint conclusion:

no adverse effect observed

Dose descriptor:

NOAEC

0.06 mg/m³

Study duration:

subchronic

Species:

rat

Quality of whole database:

The data is K2 level since the data is from a peer-reviewed journal

Repeated dose toxicity: inhalation - local effects

Endpoint conclusion

Endpoint conclusion:

no study available

Repeated dose toxicity: dermal - systemic effects

Endpoint conclusion

Endpoint conclusion:

no study available

Repeated dose toxicity: dermal - local effects

Endpoint conclusion

Endpoint conclusion:

no study available

Additional information

Various peer reviewed publications available for the target chemical and its read across was reviewed to determine the oral, inhalation and dermal toxic nature of Ethyl butyrate. The studies are as mentioned below:

Repeated dose toxicity: Oral

In a repeated oral toxicity study, male and female rats were administered 14.4 mg/kg bw of test substance in diet for 12 weeks. No adverse effects were noted in the animals at the mentioned dose level. The No Observed Adverse Effect Level (NOAEL) was considered to be 14.4 mg/kg bw when male and female rats were exposed to Ethyl butyrate for 12 weeks.

28 days repeat dose oral toxicity study was performed to determine the toxic nature of the test chemical. The study was performed using male and female Crj: CD, SPF Sprague dawley rats. The test chemical was dissolved in olive oil and used at dose level of 0, 20, 140 or 1000 mg/Kg/day for 28 days and 0 and 1000 mg/Kg/day during the 14 days recovery period. The doses for the main study were based on the preliminary dose range finding study conducted. 6 male and 6 females were used per dose group in the test and recovery period. During the study period, the test animals were observed for general condition, body weight changes, food intake, hematology, clinical signs, urinalysis and were subjected to gross and histopathology. During the administration period, salivation was observed in males and females at 1000 mg / kg group, but this symptom disappeared due to suspension of administration. This change was found transiently after administration and was also observed before administration. Body weights in both sexes were similar to those in the control group. Feeding amount was the same value as in the control group in both sexes with each test substance administered group. On examination at the end of dosing, shortening of APTT was seen in males in the 20 mg / kg group, and MCHC decreased and white blood cell counts were found in males in the 1000 mg / kg group in the examination at the end of recovery. All of these were either dose-independent changes or minor changes and were judged to be accidental changes within the physiological variation range. Fluctuation of pH to acidic side was observed in female of 20 mg / kg group, but it was a change without dose dependence, and it was judged as accidental change. In the examination at the end of administration, the wet weight of the kidney was decreased in the males of the 140 mg / kg group, but it was a minor change with no dose dependency and it was judged to be an accidental change within the physiological variation range. White nodule formation with 1 cm in diameter of the spleen and bleeding spots in the lung were observed in each case as accidental changes. No change due to administration of the test substance was observed in any group. In the control group or 1000 mg / kg group, diffuse liver and micro granulation of liver, basophilic change of renal tubular epithelium, vitreous column and vitreous droplet of renal tubular epithelium appeared. Both of these were frequently expressed changes as spontaneous changes, and there was no dose correlation in expression frequency. Based on the observations made, the No observed adverse effect level (NOAEL) for the test chemical is considered to be 1000 mg/Kg/day when male and female Sprague dawley rats were exposed to the test chemical for 28 days.

In repeated dose oral toxicity study, male and female Osborne-Mendel rats were exposed to the test chemical in a concentration of 0, 50 and 500 mg/kg at weekly basis by oral (feed). The animals were observed for body weight, food intake and general condition. Hematological examnation was performed at termination of the study. At the termination of the experiments the rats were sacrificed and exsanguinated. As earlier mentioned in the study that microscopic examination was first performed at high dose, if any significant change was observed related to compound then microscopic examination was performed for low dose level. No significant change were observed in growth, hematology, macroscopic and microscopic examination at 500 mg/kg (high dose level). Based on the observations made, the No Observed Adverse Effect Level (NOAEL) was considered to be 500 mg/kg for the test chemical treatment was given to male and female Osborne-Mendel rats for 13 weeks by oral (feed) route of exposure.

 

Repeated dose toxicity: Inhalation

 In a repeated inhalative toxicity study male and female Sprague-Dawley Crl:CD rats were exposed to Ethyl butyrate (CAS no 105 -54 -4) 1 hours/day, 5 days/week for 13 weeks of exposure and 13 weeks of recovery. Exposure to smoke from reference or test cigarettes in both studies induced increases in blood carboxyhemoglobin ((COHb)) and plasma nicotine, decreases in minute volume, differences in body or organ weights compared to air controls, and a concentration-related hyperplasia, squamous metaplasia, and inflammation in the respiratory tract. All these effects were greatly decreased or absent following the recovery period. Comparison of rats exposed to similar concentrations of test and reference cigarette smoke indicated no difference at any concentration. Thus, the results did not indicate any consistent differences in toxicological effects between smoke from cigarettes containing the flavoring or casing ingredients and reference cigarettes. Therefore, NOAEL was considered to be 0.06 mg/L when male and female Sprague-Dawley Crl:CD rats were exposed to Ethyl butyrate by inhalation of cigarette smoke for 13 weeks.

Repeated dermal study;

The acute toxicity value for Ethyl butyrate (105-54-4) (as provided in section 7.2.3) is >2000 mg/kg body weight. Also, given the use of the chemical; repeated exposure by the dermal route is unlikely since the use of gloves is common practice in industries. Thus, it is expected that Ethyl butyrate  shall not exhibit 28 day repeated dose toxicity by the dermal route. In addition, there is no data available that suggests that Ethyl butyrate shall exhibit repeated dose toxicity by the dermal route. Hence this end point was considered for waiver.

Based on the data available for the test chemical Ethyl butyrate (105-54-4)  does not exhibit toxic nature upon repeated exposure by oral, inhalation and dermal route of exposure and hence is not likely to classify as per the criteria mentioned in CLP regulation.

Justification for classification or non-classification

Based on the data available for the test chemical Ethyl butyrate (105-54-4)  does not exhibit toxic nature upon repeated exposure by oral, inhalation and dermal route of exposure and hence is not likely to classify as per the criteria mentioned in CLP regulation.