Pentyl propionate

Endpoint summary

Description of key information

There is a 28-day repeated dose inhalation study in rats for n-pentyl propionate and along with a 2 -week oral range finder (females only) but no repeated dose dermal study available. In addition, there are several repeated dose inhalation studies ranging from 9 days to 90 days in duration for the other substances in the category, n-propyl propionate and n-butyl propionate refer to the justification for read across attached to section 13 of the dataset).  The only common finding across all the studies has been histopathologic changes in the nasal tissues (olfactory epithelium damage) and this can be considered to be a local effect, while again across all the studies there have been no major indications of any systemic toxicity up to the highest doses tested.

Key value for chemical safety assessment

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:

supporting study

Study period:

2020

Reliability:

2 (reliable with restrictions)

Principles of method if other than guideline:

The purpose of this study was to assess the potential for systemic toxicity of pentyl propionate, when administered by oral gavage to female Sprague Dawley rats for 14 days.
Three groups, each comprising of four female Sprague Dawley rats, received pentyl propionate at doses of 500, 750 or 1000 mg/kg/day. A similarly constituted control group received the vehicle, corn oil, at the same volume dose as the treated groups.
During the study, clinical condition, body weight, food consumption, visual water consumption, organ weight and macropathology investigations were undertaken.

GLP compliance:

no

Specific details on test material used for the study:

Test item: Pentyl propionate
Test item identity (including alternative names): Amyl propionate, 1-Pentyl propionate
CAS number: 624-54-4
Appearance: Colorless, clear liquid.
Storage conditions: At ambient temperature (15 to 25°C). Flammable liquid and vapor, therefore containers were kept tightly sealed and away from heat, sparks, open flames and hot
surfaces.
Supplier: Sponsor
Batch number D229I9D725
Recertification date: 17 April 2021
Purity: 99.96%
Specific gravity: 0.87
Appearance: Colorless, clear liquid.

Species:

rat

Strain:

other: Crl:CD(SD)

Details on species / strain selection:

The rat was chosen as the test species because it is accepted by regulatory agencies. The Sprague Dawley [Crl:CD(SD)] strain was used because of the historical control data available at this laboratory.

Sex:

female

Details on test animals or test system and environmental conditions:

Number of animals: 20 females.
The spare animals remained in the study room throughout the treatment period. They were retained for the possibility that they might be required to form another dose group should the objective of the study not be met with the designated three dose groups.
Duration of acclimatization:
Group 1 and 2: Eight days before commencement of treatment.
Group 3 and 4: 20 days before commencement of treatment.
Age of the animals at the start of treatment:
Group 1 and 2: Approximately 73 days
Group 3 and 4: Approximately 85 days
Weight range of the animals at the start of treatment:
Group 1 and 2: 239 to 290 g
Group 3 and 4: 265 to 297 g

Animal facility: Limited access - to minimize entry of external biological and chemical agents and to minimize the transference of such agents between rooms.
Air supply: Filtered fresh air which was passed to atmosphere and not recirculated.
Temperature and relative humidity: Monitored and maintained within the range of 20-24ºC and 40-70%.
There were no deviations from these ranges.
Lighting: Artificial lighting, 12 hours light : 12 hours dark.
Electricity supply: Public supply with automatic stand-by generators.

Cages: Polycarbonate body with a stainless steel mesh lid, changed at appropriate intervals.
Cage distribution: Females were blocked by group and the cages constituting each group were dispersed in a battery so that possible environmental influences arising from their spatial distribution were equilibrated, as far as was practicable.
Number of animals per cage: Two, unless reduced by mortality.
Bedding: Wood based bedding which was changed at appropriate intervals each week.

Diet: SDS VRF1, pelleted diet.
Availability: Non-restricted.

Water Supply: Potable water from the public supply via polycarbonate bottles with sipper tubes. Bottles were changed at appropriate intervals.
Availability: Non-restricted.

Route of administration:

oral: gavage

Details on route of administration:

Route of Administration:
The oral gavage route of administration was chosen because it is the preferred route of exposure specified in the relevant subsequent studies test guidelines.

Rationale for Dose Level Selection:
The doses used in this study (0, 500, 750 and 1000 mg/kg/day) were selected in conjunction with the Sponsor.
The initial dose selected for dosing Group 2 animals was 500 mg/kg/day based on the results of an acute oral toxicity study in the Sprague-Dawley rat that indicate the LD50 is greater than 16 mL/kg (Meyers and Christopher, 1988), which is equivalent to greater than 13920 mg/kg based on a specific gravity of 0.87 for pentyl propionate.
After five consecutive days of dosing the Group 2 animals with pentyl propionate at 500 mg/kg/day, there were no clinical signs observed or changes in body weight, body weight gain or food consumption. Therefore, a high dose of 1000 mg/kg/day (limit dose) was selected for administration to the Group 4 animals and an intermediate dose of 750 mg/kg/day was selected for Group 3 (representing the median between the low and high dose).

Vehicle:

corn oil

Details on oral exposure:

PREPARATION OF DOSING SOLUTIONS:
Method of preparation:
The required amount of test item was weighed out and 50% of the final volume of vehicle was added to the test item. The formulation was magnetically stirred until all the test item was uniformly mixed. Vehicle was added to achieve the final required volume and the formulation was magnetically stirred until homogenous. Magnetic stirring was continued during the transfer of the formulations, via syringe, to the final containers.

Frequency of preparation:
At least weekly. The frequency of preparation was dependent on the ongoing receipt of the stability results from Covance Study Number FC62JS. Initially the test item formulations were prepared daily but preparations in the latter part of the study covered one week of dosing.

Storage of formulation: Refrigerated temperature (2-8°C).

Vehicle: Corn oil.

DOSE ADMINISTRATION:
Route: Oral, by gavage, using a suitably graduated syringe and a rubber catheter inserted via the mouth.
Treated at: Selected doses in mg/kg/day.
Volume: dose 4 mL/kg/day.
Individual dose volume: Calculated from the most recently recorded scheduled body
weight.
Control (Group 1): Vehicle at the same volume dose as the treated groups.

Frequency: Once daily at approximately the same time each day.
Groups 2, 3 and 4 were dosed for 14 days. As a result of the staggered start of dosing, Group 1 animals were dosed for 26 days as their necropsy coincided with that of Groups 3 and 4.

Formulation: Formulations were stirred using a magnetic stirrer before and throughout the dosing procedure.
A daily record of the usage of formulation was maintained based on weights. This balance was compared with the expected usage as a check of correct administration. No significant discrepancy was found.

Analytical verification of doses or concentrations:

yes

Details on analytical verification of doses or concentrations:

Homogeneity and stability: The homogeneity and stability of formulations during storage was determined as part of another study.
Formulations were shown to be stable when stored as follows:
Ambient temperature (15-25°C) for 24 hours.
Refrigerated temperature (2-8°C) for 15 days.

Achieved concentration: The dose formulation prepared for dosing to Group 2 on Days 9 to 14 of treatment was analyzed for achieved concentration. This was necessary because the dose containers for this group were stored at ambient temperature for more than 24 hours (correct storage for these dose pots
was refrigerated temperature).
The analysis was to determine if the prolonged storage at ambient temperature had any impact on the test item content in the formulation.

Analysis: Three dose containers labelled for dosing to Group 2 on 09, 10 and 11 September were sent to the Department of Dose Formulation Analysis at Covance Huntingdon and on receipt were placed in refrigerated storage (2-8°C).
The dose formulation in the dose pot labelled 11 September 2019 was analyzed. Prior to analysis the dose formulation was magnetically stirred for a minimum of 20 minutes and two 1 mL samples (accurately weighed) were taken from the middle of the formulation. Both samples were analyzed.
The analytical method involved the extraction and dilution of the test formulation with acetone followed by gas chromatographic assay using FID detection.
The residual sample and the dose containers labelled 09 and 10 September were disposed of once satisfactory results were obtained.

Duration of treatment / exposure:

14 Days

Frequency of treatment:

Once daily at approximately the same time each day.

Dose / conc.:

500 mg/kg bw/day (nominal)

Dose / conc.:

750 mg/kg bw/day (nominal)

Dose / conc.:

1 000 mg/kg bw/day (nominal)

No. of animals per sex per dose:

Four per dose group

Control animals:

yes, concurrent vehicle

Observations and examinations performed and frequency:

Clinical Observations:
Animals were inspected visually at least twice daily for evidence of ill-health or reaction to treatment. Cages were inspected daily for evidence of animal ill-health amongst the occupants. Any deviation from normal was recorded at the time in respect of nature and severity, date and time of onset, duration and progress of the observed condition, as appropriate.
During the acclimatization period, observations of the animals and their cages were recorded at least once per day.

Signs Associated with Dosing:
Detailed observations were recorded daily at the following times in relation to dose administration:
Pre-dose.
As each animal was returned to its home cage.
One to two hours after dosing each group.
As late as possible in the working day.

Clinical Signs:
A detailed physical examination was performed on each animal three days before commencement of treatment, once during each treatment week and on Day 15 (Groups 2, 3 and 4) or Day 27 (Group 1) before dispatch to necropsy, to monitor general health.

Mortality:
A viability check was performed near the start and end of each working day.

Body Weight:
The weight of each animal was recorded three days before treatment commenced, on the day that treatment commenced (Day 1), daily throughout the study and before necropsy.

Food Consumption:
The weight of food supplied to each cage, that remaining and an estimate of any spilled was recorded for the three days before treatment started and daily throughout the study.

Water Consumption:
Fluid intake was scheduled to be assessed by daily visual observation from Day -3 until termination. For Groups 3 and 4 the observations were not undertaken in the pre-treatment phase of the study (See Section 4). No effect on water consumption was observed and consequently quantitative measurements were not performed.

Sacrifice and pathology:

Terminal Investigations:
Method of Kill:
Carbon dioxide asphyxiation with subsequent exsanguination.

Necropsy:
All animals were subject to a detailed necropsy. After a review of the history of each animal, a full macroscopic examination of the tissues was performed. All external features and orifices were examined visually. Any abnormality in the appearance or size of any organ and tissue (external and cut surface) was recorded and the required tissue samples preserved in appropriate fixative.
The retained tissues were checked before disposal of the carcass.

Organ Weights:
Kidneys (weighed together) and liver were weighed for all animals killed at the scheduled intervals.

Fixation:
Tissues were preserved in 10% Neutral Buffered Formalin

Statistics:

The report contains serial observations pertaining to all days of study completed. In the case of clinical signs, body weight and food consumption data, only information from the final three days of the acclimatization period are presented.
Summary statistics (e.g. means and standard deviations) presented in this report were calculated from computer-stored individual raw data. Group mean values and standard deviations were frequently calculated using a greater number of decimal places than presented in the appendices. It is, therefore, not always possible to derive exact group values from the data presented in the appendices.

Clinical signs:

effects observed, treatment-related

Description (incidence and severity):

The general appearance and behaviour of all animals were unaffected by treatment. On Days 10 and 11 of treatment piloerection was seen after dosing in females receiving 1000 mg/kg/day (seen in two animals on Day 10 and four animals on Day 11).

Mortality:

mortality observed, non-treatment-related

Description (incidence):

One animal died prematurely; a female that received 500 mg/kg/day (Group 2: Animal No. 6) was found dead on Day 9 of treatment, with no prior signs recorded. The macroscopic examination revealed distension of the stomach, abnormally dark content of the duodenum, edema of the thymus gland and clear fluid in the thoracic cavity. This death was considered incidental and not related to treatment.

Body weight and weight changes:

effects observed, treatment-related

Description (incidence and severity):

There was an initial effect on body weight gain in females receiving 750 or 1000 mg/kg/day. In these two groups, all animals lost weight on the first day after dosing and thereafter their body weight gains were variable. This resulted in lower overall group mean weight gains in these two groups when compared with the Controls.
The body weight gains of females receiving 500 mg/kg/day were broadly similar to controls.

Food consumption and compound intake (if feeding study):

no effects observed

Description (incidence and severity):

There was no effect of treatment on food consumption.
Food consumption in all groups was generally slightly lower during treatment compared with pre-treatment values. The difference was considered likely due to the use of corn oil as the formulation vehicle since corn oil inherently has a degree of calorific content, such that the animals require less food intake to maintain their nutritional requirements.

Organ weight findings including organ / body weight ratios:

no effects observed

Description (incidence and severity):

There were no treatment-related effects on kidney or liver weights at any dose level.

Gross pathological findings:

no effects observed

Description (incidence and severity):

There were no adverse findings reported at the macroscopic examinations.

Remarks on result:

not measured/tested

Critical effects observed:

no

Formulation Analysis:

The dose formulation prepared for dosing to the Group 2 animals on Days 9 to 14 of treatment was stored incorrectly. Samples were subsequently taken from this formulation and analyzed for achieved concentration. The results were within acceptable limits (RME limits: maximum % 10, minimum % -15) demonstrating that the prolonged storage of the dose at ambient temperature had no impact on the integrity of the study.

Conclusions:

Treatment of non-pregnant Sprague Dawley rats with pentyl propionate at doses up to and including 1000 mg/kg/day for 14 days was well tolerated. At dose levels of 750 and 1000 mg/kg/day slight body weight losses were seen after the first day of dosing and body weights in these groups of animals continued to fluctuate during the remainder of the treatment period, resulting in slightly lower overall body weight gains when compared to controls.

Executive summary:

The purpose of this study was to assess the potential for systemic toxicity of pentyl propionate, when administered by oral gavage to female Sprague Dawley rats for 14 days.

Three groups, each comprising of four female Sprague Dawley rats, received pentyl propionate at doses of 500, 750 or 1000 mg/kg/day. A similarly constituted control group received the vehicle, corn oil, at the same volume dose as the treated groups.

During the study, clinical condition, body weight, food consumption, visual water consumption, organ weight and macropathology investigations were undertaken.

There were no premature deaths related to treatment. One female receiving 500 mg/kg/day (Group 2: Animal No. 6) was found dead on Day 9 of treatment, with no prior signs recorded. The macroscopic examination revealed distension of the stomach, abnormally dark contents of the duodenum, edema of the thymus gland and clear fluid in the thoracic cavity; this death was considered incidental and not related to treatment.

The general appearance and behaviour of the animals were unaffected by treatment. On Days 10 and 11 of treatment piloerection was seen after dosing in females receiving 1000 mg/kg/day (seen in two animals on Day 10 and four animals on Day 11).

There was an effect on body weight gain in females receiving 750 or 1000 mg/kg/day. In these two groups all animals lost weight on the first day after dosing. Thereafter, the bodyweights of these animals fluctuated resulting in lower overall group mean weight gains

when compared to controls. The body weight gains of females receiving 500 mg/kg/day were not affected by treatment.

Food and water consumption were not affected by treatment with pentyl propionate.

There were no adverse findings at macroscopic examination and there were no kidney or liver weight effects.

Endpoint conclusion

Endpoint conclusion:

no adverse effect observed

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:

weight of evidence

Study period:

2010

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: The study was conducted according to OECD TG 412, EU Method B.8 and in accordance with the Principles of Good Laboratory Practice (GLP).

Reason / purpose for cross-reference:

reference to same study

Reason / purpose for cross-reference:

reference to other study

Qualifier:

according to guideline

Guideline:

OECD Guideline 412 (Subacute Inhalation Toxicity: 28-Day Study)

Deviations:

no

Remarks:

The GLP status of the certificate of anaylsis for the analytical standard used for the determination of exposure chamber concentration could not be verified

Qualifier:

according to guideline

Guideline:

EU Method B.8 (Subacute Inhalation Toxicity: 28-Day Study)

Deviations:

no

Remarks:

same as above

Principles of method if other than guideline:

not applicable

GLP compliance:

yes

Limit test:

no

Species:

rat

Strain:

Sprague-Dawley

Sex:

male/female

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Source: Charles River Laboratories, Inc.
- Age at study initiation: 8-9 weeks
- Housing: group housed (2-3 rats/cage) during acclimation and individually housed in stainless steel cages after randomization
- Diet (e.g. ad libitum): Animals were provided LabDiet Certified Rodent Diet #5002 (PMI Nutrition International, St. Louis, Missouri) in meal form, ad libitum, except during exposure
- Water (e.g. ad libitum): Municipal water was provided ad libitum
- Acclimation period: one week prior to start of the study

ENVIRONMENTAL CONDITIONS
- Temperature (°C): 22 ± 1°C
- Humidity (%): 40-70%
- Air changes (per hr): 12-15 times/hour
- Photoperiod (hrs dark / hrs light): 12-hour light/dark

Route of administration:

inhalation

Type of inhalation exposure:

whole body

Vehicle:

not specified

Remarks on MMAD:

MMAD / GSD: not applicable

Details on inhalation exposure:

GENERATION OF TEST ATMOSPHERE / CHAMBER DESCRIPTION
- Exposure apparatus: The animals were exposed to filtered air or n-pentyl propionate vapors in 2 m3 stainless steel and glass Rochester-type whole body exposure chambers (1.3 meters x 1.2 meters wide x 1.2 meters deep with a pyramidal top and bottom).
- Method of holding animals in test chamber: Rats were singly-housed to minimize crowding during the exposure
- Source and rate of air: filtered air
- Chamber airflow was maintained at approximately 450 liters per minute. This flow rate was sufficient to provide the normal concentration of oxygen to the animals and 12-15 calculated air changes per hour. The chambers were operated at a slightly negative pressure, relative to the surrounding area. Rats were singly-housed to minimize crowding during the exposure. The time to equilibrium (T99) was 20.5 minutes.
The various concentrations of n-pentyl propionate were generated using the glass J-tube method. Liquid test material was pumped into the glass J-tube assemblies (1 per exposure chamber) and vaporized by the flow of nitrogen gas passing through the bead bed of the glass J-tube. The nitrogen was heated as needed with a flameless heat torch (FHT-4, Master Appliance Corporation, Racine, Wisconsin) to the minimum extent necessary to vaporize the test material. All chambers, including the 0 ppm (control) chamber received the same amount (35 liters per minute) of supplemental nitrogen (carrier gas). The minimum amount of nitrogen necessary to reach the desired chamber concentrations was used. The generation system was electrically grounded and the J-tubes were changed as needed. The vaporized test material and carrier gas were mixed and diluted with supply air to achieve a total flow of 450 liters per minute at the desired test chamber concentration.

Analytical verification of doses or concentrations:

yes

Details on analytical verification of doses or concentrations:

The chamber concentrations of n-pentyl propionate, measured approximately in the center of the breathing zone of the animals, were determined at least once per hour with a Miran 1A infrared (IR) spectrophotometer (Foxboro/Wilks, South Norwalk, Connecticut). The chamber analytical concentrations were collected from IR, printed and stored using a CAMILE data acquisition and control system. The IR spectrophotometer was calibrated and a standard curve was compiled prior to and at the end of the study, with standards of vaporized test material generated dynamically in the chamber in which the animals were exposed to cover the range of exposure concentrations tested. The IRdetermined concentration during each exposure was interpolated from the standard curve. The IR system was checked prior to each exposure with a standard of known concentration. Output from the infrared spectrophotometer was monitored by the CAMILE TG Data Acquisition and Control System, displayed, logged to memory, and printed for inclusion in the study file.
To determine the actual concentrations of n-pentyl propionate within the exposure chambers a pump and tube sampling method was employed. A 780- mg silica gel tube (SKC Cat# 226-15) was connected directly to the exposure chamber and chamber atmosphere was drawn through for 10 minutes at ~40 mL/min. The tubes were desorbed in acetone and the extracts analyzed for n-pentyl propionate using gas chromatography with flame ionization detection (GC/FID). At least weekly, a sample from each exposure chamber was taken using the tube method described above. These samples served as exposure chamber reference standards and were used to derive a weekly correction factor that was applied to all IR-determined values collected that week (correction factor = mean weekly chamber concentration determined via the tube method/mean weekly chamber concentration based on the IR measurements).
Airflow through the chambers was determined by measuring the pressure drop across a calibrated orifice plate, and was maintained at approximately 450 liters per minute. Chamber airflow data were collected using Setra Differential Pressure Transducers (Setra Systems, Inc., Monterey, California). The signal from the pressure transducer was sent to the CAMILE TG Acquisition and Control System and recorded in liters per minute. The differential pressure transducer was calibrated with a gas meter (Singer Aluminum Diaphragm Meter, Model AL-1400, American Meter Division, Philadelphia, Pennsylvania) prior to the start of the study. Chamber temperature and relative humidity data were collected using Omega HX94C Probes (Omega Engineering Inc., Stamford, Connecticut) coupled to the CAMILE TG Data Acquisition and Control System. Calibration of the temperature and relative humidity sensors was conducted prior to the start of the study. The chamber temperature and relative humidity were controlled by a system designed to maintain values of approximately 22 ± 2 °C and 30 - 70%, respectively. Chamber temperature, relative humidity, and airflow data were automatically recorded from the CAMILE TG Data Acquisition and Control System once per hour for all chambers with the exception of the airflow for the control (0 ppm) chamber. The control (0 ppm) chamber was not hard-wired to CAMILE to allow automatic collection of airflow data. Therefore, for the control chamber, once per hour chamber airflow data were manually recorded from a calibrated magnehelic in the chamber exhaust stream.

Duration of treatment / exposure:

6 hours/day, 5 days/week for 4 consecutive weeks (20 exposures)

Frequency of treatment:

6 hours/day, 5 days/week for 4 consecutive weeks (20 exposures)

Remarks:

Doses / Concentrations:
0 ppm (chamber concentration)
Basis:
other: 0 pppm (nominal and analytical concentration)

Remarks:

Doses / Concentrations:
100 ppm (chamber concentration)
Basis:
other: 141.0 ± 3.3 ppm (nominal concentration); 116.3 ± 4.5 ppm (analytical concentration)

Remarks:

Doses / Concentrations:
300 ppm (chamber concentration)
Basis:
other: 443.9 ± 43.3 ppm (nominal concentration); 350.0 ± 24.6 ppm (analytical concentration)

Remarks:

Doses / Concentrations:
1000 ppm (chamber concentration)
Basis:
other: 1462.2 ± 29.6 ppm (nominal concentration); 1375.0 ± 195.2 ppm (analytical concentration)

No. of animals per sex per dose:

5 males + 5 females/dose group

Control animals:

yes, sham-exposed

Details on study design:

- Dose selection rationale: based on studies conducted earlier
- Rationale for animal assignment: animals were stratified by body weight and then randomly assigned to treatment groups using a computer program designed.
- Rationale for selecting satellite groups: not applicable
- Post-exposure recovery period in satellite groups: not applicable
- Section schedule rationale: not applicable

Positive control:

not applicable

Observations and examinations performed and frequency:

CAGE SIDE OBSERVATIONS: Yes
- Time schedule: at least once a day usually in the morning

DETAILED CLINICAL OBSERVATIONS: Yes
- Time schedule: on all animals pre-exposure and once per week throughout the study

BODY WEIGHT: Yes
- Time schedule for examinations: All rats were weighed pre-exposure and twice per week during the exposure period. Body weight gains were calculated

FOOD CONSUMPTION:
- Food consumption for each animal determined: Yes. Feed consumed was determined at least weekly for all animals.

OPHTHALMOSCOPIC EXAMINATION: No

HAEMATOLOGY: Yes
- Time schedule for collection of blood: at termination
- Anaesthetic used for blood collection: Yes (O2/CO2)
- Animals fasted: Yes
- How many animals: all animals
- Parameters examined: Hematologic parameters were assayed using the Bayer Advia 120 Hematology Analyzer (Siemens Medical Solutions Diagnostics, Tarrytown, New York). Hematocrit (HCT), Hemoglobin (HGB) concentration, Red blood cell (RBC) count, Total white blood cell (WBC) count, Differential WBC count, Platelet (PLT) count, Reticulocyte (RET) count, RBC indices: Mean Corpuscular Hemoglobin (MCH), Mean Corpuscular Volume (MCV), Mean Corpuscular Hemoglobin Concentration (MCHC) and Coagulation - Prothrombin time (Blood samples were collected in sodium citrate tubes, centrifuged, plasma collected, and assayed using the Instrumentation Laboratory ACL9000 Analyzer (Beckman Coulter, Inc., Miami, Florida). Blood samples for a complete blood count were mixed with ethylenediaminetetraacetic acid (EDTA). Blood smears were prepared, stained with Wright- Giemsa stain, cover-slipped and archived for potential future evaluation if warranted.

CLINICAL CHEMISTRY: Yes
- Time schedule for collection of blood: at termination
- Animals fasted: Yes
- How many animals: all animals
- Parameters examined: Blood samples were collected and sera were separated from cells as soon as possible. Serum parameters were measured using a Hitachi 912 Clinical Chemistry Analyzer (Roche Diagnostics, Indianapolis, Indiana). Alkaline phosphatase (ALP), Alanine aminotransferase (ALT), Aspartate aminotransferase (AST), Gamma-glutamyl transpeptidase (GGT), Albumin (ALB), Albumin/Globulin Ratio (A/G) - calculated, Cholesterol (CHOL), Creatinine (CREA),
Electrolytes (NA, K, PHOS, CL and CA), Globulin (GLOB) - calculated, Glucose (GLUC), Total bilirubin (TBIL), Total protein (TP), Triglycerides (TRIG), Urea nitrogen (UN)

URINALYSIS: No

NEUROBEHAVIOURAL EXAMINATION: No

Sacrifice and pathology:

GROSS PATHOLOGY: Yes
HISTOPATHOLOGY: Yes
OTHER: Organ weights (Absolute and relative)

Other examinations:

None

Statistics:

Standard statistical methods were employed

Clinical signs:

no effects observed

Mortality:

no mortality observed

Body weight and weight changes:

effects observed, treatment-related

Food consumption and compound intake (if feeding study):

no effects observed

Food efficiency:

not examined

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

not examined

Ophthalmological findings:

not examined

Haematological findings:

no effects observed

Clinical biochemistry findings:

no effects observed

Urinalysis findings:

not examined

Behaviour (functional findings):

not examined

Organ weight findings including organ / body weight ratios:

no effects observed

Gross pathological findings:

no effects observed

Histopathological findings: non-neoplastic:

effects observed, treatment-related

Histopathological findings: neoplastic:

no effects observed

Details on results:

CLINICAL SIGNS AND MORTALITY - No treatment related clinical findings were noted in any of the animals and there were no incidences of mortality noted

BODY WEIGHT AND WEIGHT GAIN - Although no time-sex-dose interaction was identified, when the data for male and female rats were combined (time-dose interaction), rats exposed to 1375 ppm had body weights that were statistically identified as lower than their respective controls. There were no statistically-significant differences in the 116 or 350 ppm exposed groups when compared to controls.

FOOD CONSUMPTION - Statistically identified lower mean feed consumption values were observed on test days 1-5 in male rats exposed to 350 and 1375 ppm when compared to their respective controls. This decrease in feed consumption was transient resolving by the second week of the study and correlated with
lower body weight gains in these groups. There were no significant differences in the amount of feed consumed for any other groups when compared to their respective controls.

HAEMATOLOGY - Males and females exposed to 116 ppm, 350 ppm or 1375 ppm had no treatment-related effect when compared to their respective controls

CLINICAL CHEMISTRY - There were no treatment related changes in any of the clinical chemistry parameters for males and females at any exposure level. However, a very slight increase in the mean chloride content was observed in females at 116 ppm. This alteration was interpreted to be unrelated to treatment because of the lack of a dose-response relationship

ORGAN WEIGHTS - There were no statistically identified or treatment-related alterations in any of the organ weights of any exposure group

GROSS PATHOLOGY - There were no treatment-related gross pathologic observations.

HISTOPATHOLOGY - Histopathologic changes attributed to repeated inhalation exposure to n-pentyl propionate were present in sections II and III of the nasal passage. The treatment-related lesions were slight, bilateral, multifocal olfactory epithelial degeneration of the the dorsal and dorso-medial meatus of all males and females exposed to 1375 ppm. The degeneration was characterized by thinning, disarray and atrophy of the olfactory epithelial cells. Individual necrotic and sloughed epithelial cells accompanied the degenerative change. Similar changes were also present in three females exposed to 350 ppm. Very slight, unilateral, focal olfactory epithelial degeneration occurred in one male and one female, exposed to 350 ppm.
Slight, unilateral, multifocal, olfactory epithelial degeneration with minimal neutrophilic inflammation was present in the nasoturbinate of section II and III of one control male, one low-dose (116 ppm) male and in one mid-dose (350 ppm) female. These unilateral changes in the control, low-and mid-dose rats were considered unrelated when compared to the anatomic distribution and the histopathology of the treatment-related change (slight, bilateral, multifocal olfactory epithelial degeneration of the the dorsal and dorso-medial meatus).

Dose descriptor:

NOEC

Remarks:

Crl:CD (SD) rats

Effect level:

116 ppm (analytical)

Based on:

test mat.

Sex:

male/female

Basis for effect level:

other: based on overall effects and the presene of treatment related histopathologic changes in the nasal airways of male and female rats exposed to 350 and 1375 ppm n-pentyl propionate, equivalent to 686 mg/m3

Critical effects observed:

not specified

None

Conclusions:

Based on the presence of treatment-related histopathologic alterations in the nasal passage of male and female rats exposed to 350 and 1375 ppm n-pentyl propionate, the no-observed-effect concentration (NOEC) for male and female Crl:CD(SD) rats repeatedly exposed to n-pentyl propionate for four weeks (20 exposures) was 116 ppm.

Executive summary:

Five male and five female Crl:CD(SD) rats per group were whole-body exposed to 0, 116, 350, or 1375 ppm (parts per million) (0, 686, 2065, or 8111 mg/m3, respectively) of n-pentyl propionate (6 hours/day, 5 days/week, 4 consecutive weeks) for 20 exposures to evaluate the potential for respiratory tract and systemic toxicity. Exposures occurred under dynamic airflow conditions. In-life observations, feed consumption, body weights, hematology, clinical chemistry, coagulation, and organ weights were evaluated. In addition, a gross necropsy was conducted followed by an extensive histopathological examination of tissues.

There were no treatment-related clinical observations, nor effects in hematology, prothrombin time, or clinical chemistry parameters. There were no treatment related gross pathologic observations. Although no time-sex-dose interaction was identified, when the data for male and female rats were combined (time-dose interaction), rats exposed to 1375 ppm had body weights that were statistically identified as lower than their respective controls. Statistically identified lower mean feed consumption values were observed on test days 1-5 in male rats exposed to 350 and 1375 ppm when compared to their respective controls. This decrease in feed consumption was transient resolving by the second week of the study and correlated with lower body weight gains seen in these groups.

Histopathologic changes attributed to repeated inhalation exposure to n-pentyl propionate were present in the nasal passage. The treatment-related lesions were slight, bilateral, multifocal olfactory epithelial degeneration of the dorsal and dorso-medial meatus of all males and females exposed to 1375 ppm. The degeneration was characterized by thinning, disarray and atrophy of the olfactory epithelial cells. Individual necrotic and sloughed epithelial cells accompanied the degenerative change. Similar changes were also present in three females exposed to 350 ppm. Very slight, unilateral, focal olfactory epithelial degeneration occurred in one male and one female, exposed to 350 ppm.

Based on the presence of treatment-related histopathologic alterations in the nasal airways of male and female rats exposed to 350 and 1375 ppm n-pentyl propionate, the no-observed-effect concentration (NOEC) for male and female Crl:CD(SD) rats repeatedly exposed to n-pentyl propionate for four weeks (20 exposures) was 116 ppm.

Endpoint conclusion

Endpoint conclusion:

no adverse effect observed

Dose descriptor:

NOAEC

8 111 mg/m³

Study duration:

subacute

Species:

rat

Quality of whole database:

good

Repeated dose toxicity: inhalation - local effects

Link to relevant study records

Reference

Endpoint:

short-term repeated dose toxicity: inhalation

Type of information:

experimental study

Adequacy of study:

weight of evidence

Study period:

2010

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: The study was conducted according to OECD TG 412, EU Method B.8 and in accordance with the Principles of Good Laboratory Practice (GLP).

Reason / purpose for cross-reference:

reference to same study

Reason / purpose for cross-reference:

reference to other study

Qualifier:

according to guideline

Guideline:

OECD Guideline 412 (Subacute Inhalation Toxicity: 28-Day Study)

Deviations:

no

Remarks:

The GLP status of the certificate of anaylsis for the analytical standard used for the determination of exposure chamber concentration could not be verified

Qualifier:

according to guideline

Guideline:

EU Method B.8 (Subacute Inhalation Toxicity: 28-Day Study)

Deviations:

no

Remarks:

same as above

Principles of method if other than guideline:

not applicable

GLP compliance:

yes

Limit test:

no

Species:

rat

Strain:

Sprague-Dawley

Sex:

male/female

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Source: Charles River Laboratories, Inc.
- Age at study initiation: 8-9 weeks
- Housing: group housed (2-3 rats/cage) during acclimation and individually housed in stainless steel cages after randomization
- Diet (e.g. ad libitum): Animals were provided LabDiet Certified Rodent Diet #5002 (PMI Nutrition International, St. Louis, Missouri) in meal form, ad libitum, except during exposure
- Water (e.g. ad libitum): Municipal water was provided ad libitum
- Acclimation period: one week prior to start of the study

ENVIRONMENTAL CONDITIONS
- Temperature (°C): 22 ± 1°C
- Humidity (%): 40-70%
- Air changes (per hr): 12-15 times/hour
- Photoperiod (hrs dark / hrs light): 12-hour light/dark

Route of administration:

inhalation

Type of inhalation exposure:

whole body

Vehicle:

not specified

Remarks on MMAD:

MMAD / GSD: not applicable

Details on inhalation exposure:

GENERATION OF TEST ATMOSPHERE / CHAMBER DESCRIPTION
- Exposure apparatus: The animals were exposed to filtered air or n-pentyl propionate vapors in 2 m3 stainless steel and glass Rochester-type whole body exposure chambers (1.3 meters x 1.2 meters wide x 1.2 meters deep with a pyramidal top and bottom).
- Method of holding animals in test chamber: Rats were singly-housed to minimize crowding during the exposure
- Source and rate of air: filtered air
- Chamber airflow was maintained at approximately 450 liters per minute. This flow rate was sufficient to provide the normal concentration of oxygen to the animals and 12-15 calculated air changes per hour. The chambers were operated at a slightly negative pressure, relative to the surrounding area. Rats were singly-housed to minimize crowding during the exposure. The time to equilibrium (T99) was 20.5 minutes.
The various concentrations of n-pentyl propionate were generated using the glass J-tube method. Liquid test material was pumped into the glass J-tube assemblies (1 per exposure chamber) and vaporized by the flow of nitrogen gas passing through the bead bed of the glass J-tube. The nitrogen was heated as needed with a flameless heat torch (FHT-4, Master Appliance Corporation, Racine, Wisconsin) to the minimum extent necessary to vaporize the test material. All chambers, including the 0 ppm (control) chamber received the same amount (35 liters per minute) of supplemental nitrogen (carrier gas). The minimum amount of nitrogen necessary to reach the desired chamber concentrations was used. The generation system was electrically grounded and the J-tubes were changed as needed. The vaporized test material and carrier gas were mixed and diluted with supply air to achieve a total flow of 450 liters per minute at the desired test chamber concentration.

Analytical verification of doses or concentrations:

yes

Details on analytical verification of doses or concentrations:

The chamber concentrations of n-pentyl propionate, measured approximately in the center of the breathing zone of the animals, were determined at least once per hour with a Miran 1A infrared (IR) spectrophotometer (Foxboro/Wilks, South Norwalk, Connecticut). The chamber analytical concentrations were collected from IR, printed and stored using a CAMILE data acquisition and control system. The IR spectrophotometer was calibrated and a standard curve was compiled prior to and at the end of the study, with standards of vaporized test material generated dynamically in the chamber in which the animals were exposed to cover the range of exposure concentrations tested. The IRdetermined concentration during each exposure was interpolated from the standard curve. The IR system was checked prior to each exposure with a standard of known concentration. Output from the infrared spectrophotometer was monitored by the CAMILE TG Data Acquisition and Control System, displayed, logged to memory, and printed for inclusion in the study file.
To determine the actual concentrations of n-pentyl propionate within the exposure chambers a pump and tube sampling method was employed. A 780- mg silica gel tube (SKC Cat# 226-15) was connected directly to the exposure chamber and chamber atmosphere was drawn through for 10 minutes at ~40 mL/min. The tubes were desorbed in acetone and the extracts analyzed for n-pentyl propionate using gas chromatography with flame ionization detection (GC/FID). At least weekly, a sample from each exposure chamber was taken using the tube method described above. These samples served as exposure chamber reference standards and were used to derive a weekly correction factor that was applied to all IR-determined values collected that week (correction factor = mean weekly chamber concentration determined via the tube method/mean weekly chamber concentration based on the IR measurements).
Airflow through the chambers was determined by measuring the pressure drop across a calibrated orifice plate, and was maintained at approximately 450 liters per minute. Chamber airflow data were collected using Setra Differential Pressure Transducers (Setra Systems, Inc., Monterey, California). The signal from the pressure transducer was sent to the CAMILE TG Acquisition and Control System and recorded in liters per minute. The differential pressure transducer was calibrated with a gas meter (Singer Aluminum Diaphragm Meter, Model AL-1400, American Meter Division, Philadelphia, Pennsylvania) prior to the start of the study. Chamber temperature and relative humidity data were collected using Omega HX94C Probes (Omega Engineering Inc., Stamford, Connecticut) coupled to the CAMILE TG Data Acquisition and Control System. Calibration of the temperature and relative humidity sensors was conducted prior to the start of the study. The chamber temperature and relative humidity were controlled by a system designed to maintain values of approximately 22 ± 2 °C and 30 - 70%, respectively. Chamber temperature, relative humidity, and airflow data were automatically recorded from the CAMILE TG Data Acquisition and Control System once per hour for all chambers with the exception of the airflow for the control (0 ppm) chamber. The control (0 ppm) chamber was not hard-wired to CAMILE to allow automatic collection of airflow data. Therefore, for the control chamber, once per hour chamber airflow data were manually recorded from a calibrated magnehelic in the chamber exhaust stream.

Duration of treatment / exposure:

6 hours/day, 5 days/week for 4 consecutive weeks (20 exposures)

Frequency of treatment:

6 hours/day, 5 days/week for 4 consecutive weeks (20 exposures)

Remarks:

Doses / Concentrations:
0 ppm (chamber concentration)
Basis:
other: 0 pppm (nominal and analytical concentration)

Remarks:

Doses / Concentrations:
100 ppm (chamber concentration)
Basis:
other: 141.0 ± 3.3 ppm (nominal concentration); 116.3 ± 4.5 ppm (analytical concentration)

Remarks:

Doses / Concentrations:
300 ppm (chamber concentration)
Basis:
other: 443.9 ± 43.3 ppm (nominal concentration); 350.0 ± 24.6 ppm (analytical concentration)

Remarks:

Doses / Concentrations:
1000 ppm (chamber concentration)
Basis:
other: 1462.2 ± 29.6 ppm (nominal concentration); 1375.0 ± 195.2 ppm (analytical concentration)

No. of animals per sex per dose:

5 males + 5 females/dose group

Control animals:

yes, sham-exposed

Details on study design:

- Dose selection rationale: based on studies conducted earlier
- Rationale for animal assignment: animals were stratified by body weight and then randomly assigned to treatment groups using a computer program designed.
- Rationale for selecting satellite groups: not applicable
- Post-exposure recovery period in satellite groups: not applicable
- Section schedule rationale: not applicable

Positive control:

not applicable

Observations and examinations performed and frequency:

CAGE SIDE OBSERVATIONS: Yes
- Time schedule: at least once a day usually in the morning

DETAILED CLINICAL OBSERVATIONS: Yes
- Time schedule: on all animals pre-exposure and once per week throughout the study

BODY WEIGHT: Yes
- Time schedule for examinations: All rats were weighed pre-exposure and twice per week during the exposure period. Body weight gains were calculated

FOOD CONSUMPTION:
- Food consumption for each animal determined: Yes. Feed consumed was determined at least weekly for all animals.

OPHTHALMOSCOPIC EXAMINATION: No

HAEMATOLOGY: Yes
- Time schedule for collection of blood: at termination
- Anaesthetic used for blood collection: Yes (O2/CO2)
- Animals fasted: Yes
- How many animals: all animals
- Parameters examined: Hematologic parameters were assayed using the Bayer Advia 120 Hematology Analyzer (Siemens Medical Solutions Diagnostics, Tarrytown, New York). Hematocrit (HCT), Hemoglobin (HGB) concentration, Red blood cell (RBC) count, Total white blood cell (WBC) count, Differential WBC count, Platelet (PLT) count, Reticulocyte (RET) count, RBC indices: Mean Corpuscular Hemoglobin (MCH), Mean Corpuscular Volume (MCV), Mean Corpuscular Hemoglobin Concentration (MCHC) and Coagulation - Prothrombin time (Blood samples were collected in sodium citrate tubes, centrifuged, plasma collected, and assayed using the Instrumentation Laboratory ACL9000 Analyzer (Beckman Coulter, Inc., Miami, Florida). Blood samples for a complete blood count were mixed with ethylenediaminetetraacetic acid (EDTA). Blood smears were prepared, stained with Wright- Giemsa stain, cover-slipped and archived for potential future evaluation if warranted.

CLINICAL CHEMISTRY: Yes
- Time schedule for collection of blood: at termination
- Animals fasted: Yes
- How many animals: all animals
- Parameters examined: Blood samples were collected and sera were separated from cells as soon as possible. Serum parameters were measured using a Hitachi 912 Clinical Chemistry Analyzer (Roche Diagnostics, Indianapolis, Indiana). Alkaline phosphatase (ALP), Alanine aminotransferase (ALT), Aspartate aminotransferase (AST), Gamma-glutamyl transpeptidase (GGT), Albumin (ALB), Albumin/Globulin Ratio (A/G) - calculated, Cholesterol (CHOL), Creatinine (CREA),
Electrolytes (NA, K, PHOS, CL and CA), Globulin (GLOB) - calculated, Glucose (GLUC), Total bilirubin (TBIL), Total protein (TP), Triglycerides (TRIG), Urea nitrogen (UN)

URINALYSIS: No

NEUROBEHAVIOURAL EXAMINATION: No

Sacrifice and pathology:

GROSS PATHOLOGY: Yes
HISTOPATHOLOGY: Yes
OTHER: Organ weights (Absolute and relative)

Other examinations:

None

Statistics:

Standard statistical methods were employed

Clinical signs:

no effects observed

Mortality:

no mortality observed

Body weight and weight changes:

effects observed, treatment-related

Food consumption and compound intake (if feeding study):

no effects observed

Food efficiency:

not examined

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

not examined

Ophthalmological findings:

not examined

Haematological findings:

no effects observed

Clinical biochemistry findings:

no effects observed

Urinalysis findings:

not examined

Behaviour (functional findings):

not examined

Organ weight findings including organ / body weight ratios:

no effects observed

Gross pathological findings:

no effects observed

Histopathological findings: non-neoplastic:

effects observed, treatment-related

Histopathological findings: neoplastic:

no effects observed

Details on results:

CLINICAL SIGNS AND MORTALITY - No treatment related clinical findings were noted in any of the animals and there were no incidences of mortality noted

BODY WEIGHT AND WEIGHT GAIN - Although no time-sex-dose interaction was identified, when the data for male and female rats were combined (time-dose interaction), rats exposed to 1375 ppm had body weights that were statistically identified as lower than their respective controls. There were no statistically-significant differences in the 116 or 350 ppm exposed groups when compared to controls.

FOOD CONSUMPTION - Statistically identified lower mean feed consumption values were observed on test days 1-5 in male rats exposed to 350 and 1375 ppm when compared to their respective controls. This decrease in feed consumption was transient resolving by the second week of the study and correlated with
lower body weight gains in these groups. There were no significant differences in the amount of feed consumed for any other groups when compared to their respective controls.

HAEMATOLOGY - Males and females exposed to 116 ppm, 350 ppm or 1375 ppm had no treatment-related effect when compared to their respective controls

CLINICAL CHEMISTRY - There were no treatment related changes in any of the clinical chemistry parameters for males and females at any exposure level. However, a very slight increase in the mean chloride content was observed in females at 116 ppm. This alteration was interpreted to be unrelated to treatment because of the lack of a dose-response relationship

ORGAN WEIGHTS - There were no statistically identified or treatment-related alterations in any of the organ weights of any exposure group

GROSS PATHOLOGY - There were no treatment-related gross pathologic observations.

HISTOPATHOLOGY - Histopathologic changes attributed to repeated inhalation exposure to n-pentyl propionate were present in sections II and III of the nasal passage. The treatment-related lesions were slight, bilateral, multifocal olfactory epithelial degeneration of the the dorsal and dorso-medial meatus of all males and females exposed to 1375 ppm. The degeneration was characterized by thinning, disarray and atrophy of the olfactory epithelial cells. Individual necrotic and sloughed epithelial cells accompanied the degenerative change. Similar changes were also present in three females exposed to 350 ppm. Very slight, unilateral, focal olfactory epithelial degeneration occurred in one male and one female, exposed to 350 ppm.
Slight, unilateral, multifocal, olfactory epithelial degeneration with minimal neutrophilic inflammation was present in the nasoturbinate of section II and III of one control male, one low-dose (116 ppm) male and in one mid-dose (350 ppm) female. These unilateral changes in the control, low-and mid-dose rats were considered unrelated when compared to the anatomic distribution and the histopathology of the treatment-related change (slight, bilateral, multifocal olfactory epithelial degeneration of the the dorsal and dorso-medial meatus).

Dose descriptor:

NOEC

Remarks:

Crl:CD (SD) rats

Effect level:

116 ppm (analytical)

Based on:

test mat.

Sex:

male/female

Basis for effect level:

other: based on overall effects and the presene of treatment related histopathologic changes in the nasal airways of male and female rats exposed to 350 and 1375 ppm n-pentyl propionate, equivalent to 686 mg/m3

Critical effects observed:

not specified

None

Conclusions:

Based on the presence of treatment-related histopathologic alterations in the nasal passage of male and female rats exposed to 350 and 1375 ppm n-pentyl propionate, the no-observed-effect concentration (NOEC) for male and female Crl:CD(SD) rats repeatedly exposed to n-pentyl propionate for four weeks (20 exposures) was 116 ppm.

Executive summary:

Five male and five female Crl:CD(SD) rats per group were whole-body exposed to 0, 116, 350, or 1375 ppm (parts per million) (0, 686, 2065, or 8111 mg/m3, respectively) of n-pentyl propionate (6 hours/day, 5 days/week, 4 consecutive weeks) for 20 exposures to evaluate the potential for respiratory tract and systemic toxicity. Exposures occurred under dynamic airflow conditions. In-life observations, feed consumption, body weights, hematology, clinical chemistry, coagulation, and organ weights were evaluated. In addition, a gross necropsy was conducted followed by an extensive histopathological examination of tissues.

There were no treatment-related clinical observations, nor effects in hematology, prothrombin time, or clinical chemistry parameters. There were no treatment related gross pathologic observations. Although no time-sex-dose interaction was identified, when the data for male and female rats were combined (time-dose interaction), rats exposed to 1375 ppm had body weights that were statistically identified as lower than their respective controls. Statistically identified lower mean feed consumption values were observed on test days 1-5 in male rats exposed to 350 and 1375 ppm when compared to their respective controls. This decrease in feed consumption was transient resolving by the second week of the study and correlated with lower body weight gains seen in these groups.

Histopathologic changes attributed to repeated inhalation exposure to n-pentyl propionate were present in the nasal passage. The treatment-related lesions were slight, bilateral, multifocal olfactory epithelial degeneration of the dorsal and dorso-medial meatus of all males and females exposed to 1375 ppm. The degeneration was characterized by thinning, disarray and atrophy of the olfactory epithelial cells. Individual necrotic and sloughed epithelial cells accompanied the degenerative change. Similar changes were also present in three females exposed to 350 ppm. Very slight, unilateral, focal olfactory epithelial degeneration occurred in one male and one female, exposed to 350 ppm.

Based on the presence of treatment-related histopathologic alterations in the nasal airways of male and female rats exposed to 350 and 1375 ppm n-pentyl propionate, the no-observed-effect concentration (NOEC) for male and female Crl:CD(SD) rats repeatedly exposed to n-pentyl propionate for four weeks (20 exposures) was 116 ppm.

Endpoint conclusion

Endpoint conclusion:

adverse effect observed

Dose descriptor:

NOAEC

683.157 mg/m³

Study duration:

subacute

Species:

rat

Quality of whole database:

good

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

The table below summarizes the key repeat dose inhalation toxicity study information for the propionate category of substances –

Compound tested	Duration of exposure	GLP	Doses tested	Guideline	NOEC (ppm)	Effects seen/ observed	Local effects (organs affected)
Pentyl propionate	28 days (20 exposures)	Yes	0, 116, 350, 1375 ppm	OECD TG 412	NOEC – 116 ppm (683.1567 mg/m3)	No effects seen up to 1375 ppm	Nasal tissues – olfactory epithelium damage
Butyl propionate	11 days (9 exposures)	Yes	0, 800, 1600, 3200 ppm	OECD TG 412	NOEC < 800 ppm	Reduced body weight and gains across all groups, reduced food and water consump. at 1600 and 3200 ppm and transient changes in clinical pathology related to reduced body weight	Nasal tissues – olfactory epithelium damage
Butyl propionate	2 weeks (10 exposures)	Yes	0, 250, 500, 2000, 4000 ppm	OECD TG 412	NOEC - 500 ppm	Reduced body weight gain, food consump. noted in 2000 and 4000 ppm groups	Nasal tissues – olfactory epithelium damage in the 2000 and 4000 ppm groups
Butyl propionate	13 weeks (5 days/week)	Yes	0, 250, 750,1500 ppm	EPA OTS 798.2450	NOEC (systemic toxicity) – 747 ppm; NOEC (local effects) – 247 ppm	Reduced body weight gains and food consump. observed at 1500 ppm	Nasal tissues – olfactory epithelium damage
Propyl propionate	2 weeks (9 exposures)	Yes	0, 50, 250, 2000 ppm	OECD TG 412	NOAEC - > 50 < 250 ppm	Reduced body weight at 2000 ppm, reversible during recovery, no other effects	Nasal tissues – olfactory epithelium damage
Propyl propionate	Approx. 30 days	Yes	0, 50, 250, 500 ppm	OECD TG 422	LOAEC – 50 ppm	Slight reductions in body weight and food consump. at 250 and 500 ppm	Nasal tissues – olfactory epithelium damage

Data on n-pentyl propionate:

In a GLP study conducted according to OECD TG 412 (Repeated Dose Inhalation Toxicity 28/14-day), five male and five female Crl:CD(SD) rats per group were whole-body exposed to 0, 116, 350, or 1375 ppm (parts per million) (0, 686, 2065, or 8111 mg/m3, respectively) of n-pentyl propionate (6 hours/day, 5 days/week, 4 consecutive weeks) for 20 exposures to evaluate the potential for respiratory tract and systemic toxicity. Exposures occurred under dynamic airflow conditions. In-life observations, feed consumption, body weights, hematology, clinical chemistry, coagulation, and organ weights were evaluated. In addition, a gross necropsy was conducted followed by an extensive histopathological examination of tissues.

There were no treatment-related clinical observations, nor effects in hematology, prothrombin time, or clinical chemistry parameters. There were no treatment related gross pathologic observations. Although no time-sex-dose interaction was identified, when the data for male and female rats were combined (time-dose interaction), rats exposed to 1375 ppm had body weights that were statistically identified as lower than their respective controls. Statistically identified lower mean feed consumption values were observed on test days 1-5 in male rats exposed to 350 and 1375 ppm when compared to their respective controls. This decrease in feed consumption was transient resolving by the second week of the study and correlated with lower body weight gains seen in these groups. As such these effects are not considered to be evidence of adverse systemic effects.

Histopathologic changes attributed to repeated inhalation exposure to n-pentyl propionate were present in the nasal passage. The treatment-related lesions were slight, bilateral, multifocal olfactory epithelial degeneration of the dorsal and dorso-medial meatus of all males and females exposed to 1375 ppm. The degeneration was characterized by thinning, disarray and atrophy of the olfactory epithelial cells. Individual necrotic and sloughed epithelial cells accompanied the degenerative change. Similar changes were also present in three females exposed to 350 ppm. Very slight, unilateral, focal olfactory epithelial degeneration occurred in one male and one female, exposed to 350 ppm.

 

Based on the presence of treatment-related histopathologic alterations in the nasal airways of male and female rats exposed to 350 and 1375 ppm n-pentyl propionate, the no-observed-effect concentration (NOEC) for local effects in both male and female Crl:CD(SD) rats repeatedly exposed to n-pentyl propionate for four weeks (20 exposures) was 116 ppm (683.1567 mg/m3). The NOAEC for systemic toxicity is considered to be the top dose of 1375 ppm (8111 mg/m3).

Due to the lack of a 90-day study on n-pentyl propionate, data on other members of the category are included to assess the potential sub-chronic repeated dose toxicity of n-pentyl propionate.

A non-GLP oral gavage range finding study was performed in female rats up to 1000 mg/kg/day. At dose levels of 750 and 1000 mg/kg/day slight body weight losses were seen after the first day of dosing with body weights in these groups continuing to fluctuate during the remainder of the treatment. This resulted in slightly lower overall body weight gains compared to control. Overall, the 14 -day oral gavage treatment with n-pentyl proionate was well tolorated.

Data on n-butyl propionate:

In a GLP study conducted according to OECD TG 412 (Repeated Dose Inhalation Toxicity 28/14 -day), groups of male and female Fischer 344 rats were exposed (whole body) to vapours of butyl propionate at levels of 800, 1600 and 3200 ppm (nominal concentration) for 6hours/day, 9 exposures over a period of 11 days. Treatment produced effects upon body weight, food and water consumption, and microscopic changes in the nasal cavities at exposure concentrations of 1600 and 3200 ppm. Decreases in body weight, body weight gain, and microscopic changes in the anterior olfactory mucosa were observed even at the lowest concentration. Thus, a no-observed-effect level (NOEL) was not determined for exposure to n-butyl propionate vapor.

In a range-finding GLP study conducted according to OECD TG 412 (Repeated Dose Inhalation Toxicity 28/14 -day), groups of male and female Sprague Dawley rats were exposed (whole body) to vapours of butyl propionate at levels of 0, 250, 500, 2000 and 4000 ppm (nominal concentration) for 6 hours/day, 10 exposures over a 2-week period. Exposure to vapours of n-butyl propionate had no adverse effect at any exposure level on survival and organ weights data. Test article-related clinical signs were noted in the 2500 and 4000 ppm groups and consisted primarily of drooping eyelids and salivation during exposure, and red or brown material or staining around the nose and/or mouth one hour following exposure. Body weight gain and food consumption were inhibited in the 2500 and 4000 ppm groups generally throughout the treatment period. Exposure-related lesions were noted at the microscopic examination of nasal tissues which consisted of cytoplasmic vacuolation, necrosis and/or atrophy of the olfactory epithelium (with or without dilatation of Bowman's glands) in nasal sections III, IV, V and VI of the 2500 and 4000 ppm groups. Based on the exposure related lesions observed in the nasal tissues, the no-observable effect level (NOEC) was considered to be 500 ppm.

In a GLP study conducted according to EPA OTS 798.2450 (90 -day Inhalation Toxicity), groups of male and female Sprague Dawley rats were exposed (whole body) to vapours of butyl propionate over a period of 13 weeks at levels of 250, 750 and 1500 ppm for 6 hours/day, 5 days/week. In conclusion, exposure of rats to n-butyl propionate for 13 weeks resulted in reduced body weight gains and food consumption in the 1500 ppm group males essentially throughout the exposure period, slight and transient reductions in body weight gain in the 1500 ppm group females and histopathologic lesions of the nasal tissues in the 750 and 1500 ppm group animals. Similar findings in the olfactory epithelium lining were also noted in animals of the dose range finding study and this was also substantiated by an independent Pathology Advisory Group. Based on the data obtained during the 8-week recovery (nonexposure) period, the effects on body weight gain and food consumption were completely reversible. The histopathological lesions showed substantial to complete reversibility at the end of the 8-week recovery period. Based on the exposure related lesions observed in the nasal tissues at the study week 13 primary necropsy, the no-observable effect level (NOEL) for olfactory epithelium damage was considered to be 247 ppm. The NOEL for systemic toxicity, based on decreased body weight gain was considered to be 747 ppm.

Data on n-propyl propionate:

In a GLP study conducted according to OECD TG 412 (Repeated Dose Inhalation Toxicity: 28/14 -day), groups of male Crl:CD (SD) IGS BR rats were exposed (whole body) to vapours of H-24826 (propyl propionate) at levels of 50, 250 and 2000 ppm (nominal concentrations) for 6 hours/day, 9 exposures over a 2 -week period. Inhalation exposure of male rats to H-24286 at concentrations of 250 or 2000 ppm produced degeneration and necrosis of the olfactory epithelium. Evidence of reversibility, though not complete, was present following the 3-week recovery period. Under the conditions of this study and based upon changes in the olfactory epithelium, the NOAEL for pathology was 50 ppm. The actual NOAEL is between 50 and 250 ppm and is expected to lie near the upper bound of that range, as effects at the low-effect level of 250 ppm were limited to a single animal and were minimal and focal in nature.

In a GLP study conducted according to OECD TG 422 (Combined Repeated Dose Toxicity Study with the Reproduction/Developmental Toxicity Screening Test), groups of male and female Crl:CD(SD) rats were exposed (whole body) to vapours of propyl propionate at levels of 50, 250 and 500 ppm (nominal concentrations) for 6 hours/day, 7 days/week. Exposure to n-propyl propionate resulted in slight reductions in food consumption and body weight throughout the study in females exposed to 250 and 500 ppm. Treatment related histopathologic effects were also evident in the nasal tissues of males and females exposed to all test concentrations. The nasal tissue effects consisted of very slight degeneration of the olfactory epithelium. In addition males exposed to 500 ppm and females exposed to 50 ppm had a higher incidence of adipose tissue atrophy than the controls. This was interpreted to have questionable significance. No treatment-related effects were seen in reproductive performance, pup survival and growth, neurologic function, clinical chemistry, or hematology. Therefore, the no-observed-effect concentration (NOEC) for general toxicity was considered to be greater than 500 ppm (the highest tested dose in this study).

 

Conclusions:

A common finding across all the propionates (n-pentyl propionate, n-butyl propionate, n-propyl propionate) was histopathologic changes in the nasal tissues (olfactory epithelium damage) and this can be considered to be a local effect, while again across all the studies there have been no major indications of any systemic toxicity up to the highest doses tested. The major effects across all the propionates have been reductions in body weights and weight gain with reduced food and water (in some instances) consumption and transient changes in clinical pathology secondary to weight loss or reduction. To conclude, it is unlikely that a 90-day study (if conducted) will lead to a reduction in NOEC, supporting this is the fact that significant decreases in NOEC values are not noted with increase in the study duration or length of the study, across all the propionates.

The key (local) effect i.e. histopathologic changes in the nasal tissues (olfactory epithelium damage) will be considered more as an irritant effect secondary to the release of propionic acid after hydrolysis by the carboxylesterases (widely distributed in the body of mammalian species and this can hydrolyse esters in various compounds).Specifically, the carboxylesterases metabolise propionates and acetates releasing these acids which can then cause local irritation of the respiratory tract epithelia.

The NOEC value of 116 ppm (683.1567 mg/m3) from the 28-day on n-pentyl propionate will be used for DNEL derivation (local effects) and DNEL’s for systemic toxicity will not be derived as they would be far less sensitive than the values used for calculation of local effects.

Justification for classification or non-classification

Based on the results noted in the repeated dose toxicity studies and based on the Guidance to Regulation (EC) No. 1272/2008 on Classification, Labelling and Packaging of substances and mixtures, pentyl propionate will not be classified for Single Target Organ Toxicity - Repeated Exposure (STOT-RE).