Carbamic acid, N-[(1R)-2-hydroxy-1-phenylethyl]-, 1,1-dimethylethyl ester

Acute Toxicity: inhalation

Administrative data

Endpoint:

acute toxicity: inhalation

Type of information:

experimental study

Adequacy of study:

key study

Study period:

June 05 2018 to March 14 2019

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2019

Report date:

2019

Materials and methods

Test guideline

Qualifier:

equivalent or similar to guideline

Guideline:

OECD Guideline 436 (Acute Inhalation Toxicity: Acute Toxic Class Method)

Version / remarks:

The Guidelines for the testing of chemicals "Acute Inhalation Toxicity-acute class method" (436) published by the Ministry of Enviornmental Protection of People's Republic of China in the year of 2013/
The classification is according to the Globally Harmonized System of Classification and Labeling of Chemicals (seventh edtion, 2017).

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Test type:

acute toxic class method

Limit test:

no

Test material

Test material information

Constituent 1

Reference substance name:

Carbamic acid, N-[(1R)-2-hydroxy-1-phenylethyl]-, 1,1-dimethylethyl ester

EC Number:

600-273-1

Cas Number:

102089-74-7

Molecular formula:

C13H19NO3

IUPAC Name:

Carbamic acid, N-[(1R)-2-hydroxy-1-phenylethyl]-, 1,1-dimethylethyl ester

Test material form:

solid: particulate/powder

Test animals

Species:

rat

Strain:

Sprague-Dawley

Sex:

male/female

Details on test animals or test system and environmental conditions:

Test System
Species: Rat
Strain: Sprague-Dawley
Grade: SPF
Supplier: Beijing Vital River Laboratory Animal Technology Co., Ltd. Animal Production License: SCXK. (Jing) 2016-0006
Animal Certificate No.: 11400700307125
Justification of test system: According to Acute Inhalation Toxicity of the MEP Guideline for Testing of Chemicals rat is the preferred strain for the heredity characters, stability, and available background data.
Number of animals: 6 animals (3 male and 3 female) were ordered and used. The females were nulliparous and non-pregnant.
Age and body weight: When exposure the age was between 63~69days and the body weight was between282~294g for male rats and 247~26lg for female rats. The body weights were within ±20% of the mean weight for each sex when exposed.

Physical examination and acclimatization
A physical examination, weighing and marking on the hair and cage card identifying was made in 24 hours after animals' arrival. After the physical examination, 12 days acclimatization period started. Animals were acclimated to the restraining tubes twice prior to dosing in order to minimize stress and uncomfortableness for restraining tubes. The first pre-adaption was about lh. The second pre-adaption was about 2 hours. No abnormalities were found during both restrainings. One or two animals were paired housed per cage during the acclimatization period.

Test conditions
Husbandry: Animals were housed in Room A120-l of the facility. Animals were raised in suspended, stainless steel cages (L32.0cm xW28.0cmxH20.0cm) on cage racks (L167.0cmxW70.0cmxH17l.0cm). There were 10 cages per layer, and 4 layers per rack. Animals were housed individually after exposure.
Environmental controls: The temperature and humidity were automatically controlled and recorded. The target value of animal room temperature was 19 C - 25 C, of the relative humidity was 40% ~ 70% and the light cycle was 12 hour light and
12 hour dark.
Food and water: Animals were provided with rodent complete nutrition pellet diet supplied by Beijing keaoxieli Feed CO., LTD. Analysis report of diet was provided by the supplier. Water was purified using the HT-RO 1000 purity system. Drinking water was routinely analyzed. Diet and drinking water were considered not to contain any contaminants that could reasonably be expected to affect the purpose or integrity of the study. During the test, diet and water were available to the animals ad libitum except for exposure.
Animal welfare: The animal use for this study complies with the national animal welfare laws and regulations (instructive notions with respect to caring for laboratory animals) (2006, PRC Ministry of Science).The animal care and use activities required for the conduct of this study were reviewed and approved by the testing facility Animal Care and Use Committee (lACUC).

Administration / exposure

Route of administration:

inhalation: aerosol

Type of inhalation exposure:

snout only

Vehicle:

not specified

Mass median aerodynamic diameter (MMAD):

1.97 µm

Geometric standard deviation (GSD):

1.59

Remark on MMAD/GSD:

Aerosol Instrument for Aerodynamic Particle Sizer (APS) 3321 was used to asses the particle size distribution of the test atmosphere.

Details on inhalation exposure:

Equipment: HOPE-MED 8052H dynamic snout only dust inhalation instrument was used.

Atmosphere Generation System: The test item was aerosolized using a stainless steel aerosol generation system. The test item was infused into generation system through peristaltic pump and mixed with compressed air. Target concentration was achieved by adjusting air flow rate and pump infusion velocity.

Exposure Method
Test item preparation: Test item had been grinded with 10% carbon-white. Before exposure, each rat was restrained in a confined transparent polycrylic tube. The exposure tubes were installed in the portholes of the inhalation chamber and the chamber was sealed up. Filtered and compressed air was mixed with quantitative test item and aerosol was sent to exposure chamber(0.04m3). The test item moving speed and exposure airflow rate had been adjusted. The aerosol had been continuously generated from generation system on the top of the chamber with an aerosol producer. A slight negative pressure was maintained in outer plenum of chamber to prevent leakage of the test substance into the surrounding area. The exhausted air was removed from the outlet at the bottom of the chamber to absorption unit. Equipment diagram is shown in appendix Figure 2.
Concentration trial: Before commencement of the exposure, technical trial had been conducted (without animals) using the inhalation system. The two concentrations' error were fallen within +20%, so the exposure had been done.

Exposure Duration: 4 hours in rats.

Monitoring of Exposure Conditions
The actual concentrations, particle size distribution at the animals' breathing zone, chamber airflow, chamber temperature, relative humidity and oxygen concentration were determined during exposure period. Detection frequency and methods see below table 2.

Analytical verification of test atmosphere concentrations:

yes

Duration of exposure:

4 h

Concentrations:

2970 mg/m^3

No. of animals per sex per dose:

3 males and 3 females

Control animals:

no

Details on study design:

Clinical Observation
Clinical observations were recorded once during the exposure and twice with more than 30 minutes interval after exposure on the exposure day and then once daily for up to end observation.
Observation and record was conducted including animal fur changes, eyes, and mucous membranes, and also respiratory, circulatory, autonomic and central nervous systems, and somatomotor activity and behavior patterns. Attention was directed to tremors, convulsions, salivation, diarrhoea, lethargy, sleep, and coma.

Body Weights
The animals were weighed in the first 24 hours after arrival, on the day of exposure prior to exposure (day 0), and on day 1, day 3, day 7 and day 14.

Necropsy and Histopathology
All surviving animals were dissected at the end of the study after anesthetizing with ether inhalation and killed by bloodletting. Nose, pharynx, larynx, trachea, and lung were examined. The necropsy included following examinations such as the external features of the carcass, external body orifices, the abdominal, thoracic, and their contents of all animals, and the location, size, hardness, and the color. No abnormalities were found in female and male animals at the gross necropsy, so histopathological examination was not performed.

Evaluation of Data
The number of animals in each group, the symptoms, the gross anatomy of the surviving animals and the frequency of various types of lesions were counted separately. The incidence of the above items in different groups for different sex and the mean and standard deviation of body weight at different times were calculated .
The inhalation toxicity LC50 range was found. According to GHS criteria for the acute inhalation toxicity (as shown in table 3 below) the test item category was given. Because unit of LC50 was mg/m3, the LC5o divided by the 1000 was converted to mg/L units when test item classification was conducted.

Results and discussion

Effect levels

Key result

Sex:

male/female

Dose descriptor:

LC50

Effect level:

> 2 970 mg/m³ air (nominal)

Based on:

test mat.

Remarks on result:

other: 2970+/-67 mg/m³

Mortality:

No animals were found dead during the test period.

Clinical signs:

other: none observed

Body weight:

The body weight of male and female animals showed increased trend during the observation period.

Gross pathology:

No abnormalities were found in female and male animals at the gross necropsy.

Applicant's summary and conclusion

Interpretation of results:

Category 4 based on GHS criteria

Conclusions:

Based on the results, the LD50 in SD rats for Boc-Phenyl-Glycinol is more than 2970+/-67 mg/m³ and it is classified to 4 or more than 4 according to GHS classification.