Registration Dossier

Administrative data

Endpoint:
acute toxicity: inhalation
Type of information:
experimental study
Adequacy of study:
key study
Study period:
2011
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
other: GLP guideline study

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
2012
Report Date:
2012

Materials and methods

Test guideline
Qualifier:
according to
Guideline:
OECD Guideline 403 (Acute Inhalation Toxicity)
Deviations:
no
GLP compliance:
yes (incl. certificate)
Test type:
acute toxic class method
Limit test:
no

Test material

Reference
Name:
Unnamed
Type:
Constituent
Test material form:
other: liquid
Details on test material:
- Identification: Sec-Butyl aminoethanol
- Description: Colourless to yellow liquid
- Batch Number: A2053H010101
- Purity: 99.76%
- Expiry Date (Retest Date): 05-Jan-2013
- Storage Conditions: At room temperature (20 ± 5°C), protected from direct sunlight.

Test animals

Species:
rat
Strain:
Wistar
Sex:
male/female
Details on test animals and environmental conditions:
TEST ANIMALS
- Animals: Rat, RccHanTM:WIST(SPF)
- Rationale: Recognized by international guidelines as a recommended rodent test system.
- Breeder: Harlan Laboratories B.V., Kreuzelweg 53, 5961 NM Horst / Netherlands
- Number of Animals per Group: 5 males and 5 females
- Number of Groups: 1
- Age at Exposure: 9 weeks
- Body Weight Range at Exposure: 273.1 to 279.6 g (males) and 177.7 to 192.2 g (females). The weight variation did not exceed ±
4% of the mean weight of the corresponding sex.
- Identification: By unique cage numbers and individual unique tail numbers written with an indelible felt-tip pen.
- Acclimatization: Performed under Harlan Laboratories Study B68308 for nine days under optimal hygienic laboratory conditions,
after a clinical health examination. Only animals without any visible signs of illness were used for the study. A further observation of
clinical signs was performed on the day of exposure, before exposure start. The animals were accustomed to the restraining tubes for
30 minutes on the day of exposure.

ENVIRONMENTAL CONDITIONS
- Room Numbers: Animal room number 3.15, Harlan Laboratories Ltd., Füllinsdorf.
- Conditions: Optimal hygienic conditions (OHC) inside a barrier system. Air-conditioned with 10 - 15 air changes per hour,
continuously monitored environment with a temperature range of 22 ± 3 °C, a relative humidity range of 30 - 70% and a 12 hour
fluorescent light / 12 hour dark cycle. Values for relative humidity above the range occasionally occurred, usually following room
cleaning, and were considered not to have any influence on the study. These data are not reported but retained at Harlan
Laboratories Ltd. A radio program was played during most of the light period.
- Accommodation: Animals were housed in groups of 5 of the same sex in Makrolon® type-IV cages with wire mesh tops and
standard softwood bedding ("Lignocel" J. Rettenmaier & Söhne GmbH & Co KG, 73494 Rosenberg / Germany, imported by Provimi
Kliba AG, 4303 Kaiseraugst / Switzerland) including paper enrichment (Enviro-dri from Lillico Biotechnology, Surrey, UK).
- Diet: Animals had ad libitum access to a pelleted standard Harlan Teklad 2914C rat maintenance diet (Provimi Kliba AG, 4303
Kaiseraugst, Switzerland) batch no. 44/11 except during the period when the animals were restrained in exposure tubes. Results of
the analyses for contaminants and their limits of acceptability are archived at Harlan Laboratories Ltd.
- Water: Community tap water from Füllinsdorf ad libitum in water bottles, except during the period when they were restrained in
exposure tubes. Results of representative analyses for contaminants are archived at Harlan Laboratories Ltd.

Administration / exposure

Route of administration:
inhalation: vapour
Type of inhalation exposure:
other: nose-only, flow-past exposure
Vehicle:
clean air
Details on inhalation exposure:
GENERATION OF TEST ATMOSPHERE / CHAMBER DESCRIPTION
- Inhalation Exposure System: Inhalation exposure was performed using a flow-past, nose-only exposure system with stainless steel tubings. The animals were confined separately in restraint tubes which were positioned radially around the exposure chamber. The exposure system ensured a uniform distribution and provided a constant flow of test material to each exposure tube. The flow of air at each tube was 1.3 L/min, which is sufficient to minimize re-breathing of the test atmosphere as it is more than twice the respiratory minute volume of rats
- Test Atmosphere Generation: The test atmosphere was generated using a glass nebulizer with a metal injector connected to a syringe pump. The temperature of the glass nebulizer was kept at 100°C to maximize the vaporization of the test item. A particle filter was placed before the exposure chamber to ensure that any aerosol droplets were retained and that the animals were exposed only to the vapor phase.

TEST ATMOSPHERE
- Exposure System Monitoring
The vapor concentration, relative humidity, temperature and oxygen concentration were measured on test atmosphere samples taken at a representative exposure port.
- Determination of the Nominal Vapor Concentration
Nominal concentration was determined during exposure by weighing the nebulizer and appropriate adjacent pipe work, before and after exposure to determine the quantity of test item used for test atmosphere generation. The weight used was then divided by the total airflow volume to give the nominal concentration.
- Gravimetric Determination of Vapor Concentrations and Determination of Particle Size Distribution
Not feasible for a vapor. In addition, as a vapor the test item was considered to be respirable.
- Chemical Determination of Vapor Concentrations
Test atmosphere samples were collected four times during exposure in a solvent trap with 100 mL acetonitrile at room temperature. The duration of sampling was 10 to 15 min. These four samples were transferred into appropriate labeled vials and forwarded immediately in a cool box to the scientist responsible for formulation analysis and stored at -20 ± 5 °C until analysis. The samples were analyzed using a GC method.
- Oxygen Concentration
The oxygen concentration of the test atmosphere was measured continuously during exposure using a calibrated device. The results were recorded manually and are reported at 30 minute intervals from the start of exposure. The oxygen concentration was maintained above 19% during exposure.
- Relative Humidity / Temperature
The temperature and relative humidity of the test atmosphere was measured continuously during exposure using a calibrated device. The results were recorded manually and are reported in 30 minute intervals from the start of exposure.
- Airflow Rate
The actual airflow rate through the exposure chamber was recorded in approximately 30 minute intervals from the start of the inhalation exposure.
Analytical verification of test atmosphere concentrations:
yes
Duration of exposure:
4 h
Concentrations:
0.76 +/- 0.06 mg/L
No. of animals per sex per dose:
5
Control animals:
no
Details on study design:
- Duration of observation period following administration: 28 days
- Viability / Mortality: Observations for viability were recorded once before exposure on the day of exposure (test day 1), three times during exposure, immediately and 1 h after exposure on test day 1 and twice daily during the observation period.
- Clinical Signs: Each animal was examined three times during exposure, immediately and 1 h after exposure on test day 1 and once daily during the observation period. Observations were detailed and carefully recorded using explicitly defined scales as appropriate. Only grossly abnormal signs were detectable during exposure as the animals were restrained in the exposure tubes.
-Body Weights: The body weight of each animal was recorded on test days 1 (before exposure), 2, 3, 4, 8, 10, 13, 15, 22, and 29 (before necropsy).
- Pathology
Necropsy: After 28 days of Observation
At the end of the observation period all surviving animals were transferred to the pathology unit and anaesthetized by an intraperitoneal injection of sodium pentobarbitone and killed by exsanguination. The animals that were prematurely killed were transferred to the pathology unit and necropsied on the same day.
All animals were necropsied and examined for macroscopic abnormalities. Samples of the following tissues and organs were collected from all animals at necropsy and fixed in neutral phosphate buffered 4% formaldehyde solution.
- Histotechnique / Histopathology: All collected organ and tissue samples are retained but neither processed nor examined.


Tissues / Organs Collected
Head with nasopharyngeal tissues X
Larynx X
Lungs, instilled via trachea with
formalin at approximately 30 cm H2O pressure X
Trachea X
All gross lesions X



Statistics:
No statistical analysis was performed as only one group was allocated to the study.

Results and discussion

Effect levels
Sex:
male/female
Dose descriptor:
LC50
Effect level:
0.76 mg/L air (analytical)
Exp. duration:
4 h
Mortality:
Three males and two females were prematurely killed for animal welfare reasons
Clinical signs:
other: All animals showed salivation during exposure. Starting generally after the end of the exposure, all animals showed ruffled fur and effects on breathing (breathing noises and/or labored breathing). In addition, general erythema, swelling, scabs and/or bla
Body weight:
All animals showed moderate to marked body weight loss. The five animals that were prematurely killed for animal welfare reasons showed severe consecutive body weight loss until their removal from the study. The other animals showed consecutive body weight loss or stagnation of body weight gain up to test day 8. Thereafter, normal body weight development was recorded in these animals until necropsy.
Gross pathology:
In animals prematurely killed for animal welfare reasons, eschar and/or sores at the skin of the head was noted in two males and two females, various regions of the intestine were distended with gas in one male and one female and the lungs and the thymus of one female showed dark red foci and/or a dark red discoloration and the forefeet of that animal showed necrosis.

In the remaining animals, the findings noted at planned necropsy were alopecia in one male and three females, one toe at the forefoot missing in one male and one female each, and one toe at the forefoot thickened in another female.

No further macroscopic findings were present at necropsy.

Applicant's summary and conclusion

Interpretation of results:
Toxicity Category II
Remarks:
Migrated information Criteria used for interpretation of results: EU
Conclusions:
The LC50 for 4-hour exposure of Sec-Butyl aminoethanol obtained in this study was 0.76 mg/L air (chemically determined mean vapor concentration). This concentration was at the technical limit for a vapor. There was no indication of relevant sex-related differences in toxicity of the test item
Executive summary:

The acute inhalation toxicity of the test item sec-butyl aminoethanol was evaluated in a study designed to be in general compliance with the OECD Guidelines for Testing of Chemicals, Section 403 and the principles of the Good Laboratory Practice. A group of five male and five female albino rats [RccHanTM:WIST(SPF)] was exposed by nose-only, flow-past inhalation for four hours to the test item at a chemically determined mean vapor concentration of 0.76 mg/L air.This concentration was at the technical limit for a vapor. All animals were observed for clinical signs and mortality during the inhalation exposure and the subsequent 28-dayobservation period. Body weights were recorded prior to exposure on test day 1, and during the observation period on test days2, 3, 4, 8, 10, 13, 15, 22, and 29. On test day 29 all surviving animals were sacrificed and necropsied. The vapor concentration, temperature, relative humidity, oxygen content and airflow rate measured during the exposure were considered to be satisfactory for a study of this type. In addition, as a vapor the test item was considered to be respirable to rats.

Three males and two females were prematurely killed for animal welfare reasons between test days 3 and 10 due to severe clinical signs or body weight loss of more than 25%. All animals showed salivation during exposure. Severe clinical signs were noted in all animals after exposure. These consisted mainly of ruffled fur, decreased activity effects on breathing (breathing noises and/or labored breathing), and/or local irritative effects (e.g. general erythema, swelling, scabs and/or black spots) resulting occasionally in bleeding areas, necrosis and/or a missing toe of the forefoot. As a consequence, the observation period was extended and only minor clinical signs were present at necropsy. All animals showed consecutive body weight loss at a moderate to marked degree. Normal body weight development was recorded from test day 8 onwards in animals surviving until necropsy. Macroscopic findings in single animals that were prematurely killed for animal welfare reasons consisted of eschar and sores at the skin of the head, forefeet with necrosis, an intestine distended with gas, as well as lungs and thymus with dark red foci and/or a dark red discoloration. Alopecia and a missing or thickened toe at the forefoot were occasionally noted in the remaining animals at planned necropsy.  

In conclusion, the 4-hour exposure of rats to 0.76 mg/L air (chemically determined mean saturated vapor concentration) of Sec-Butyl aminoethanol resulted in severe clinical signs (mainly effects on breathing and local irritative effects), corresponding effects at necropsy, marked body weight loss, allpresumably irreversibleand accordingly three males and two females were prematurely killed for animal welfare reasons. Therefore, the 4-hour exposure LC50 for Sec-Butyl aminoethanol is assumed to be close to the saturated vapor concentration of 0.76 mg/L air. There was no indication of relevant sex-related differences in toxicity of the test item.