2-[(1-methylpropyl)amino]ethanol

Endpoint summary

Description of key information

Sec-Butyl aminoethanol  is irritating for the nasal passages after a subacute inhalation exposure. No other target organs were identified in repeated dose toxicity studies either by inhalation or oral routes.

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:

key study

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: GLP guideline study

Qualifier:

according to guideline

Guideline:

other: OECD Guideline 421 (Reproduction / Developmental Toxicity Screening Test)

Deviations:

yes

Remarks:

additional histopathological examinations were performed

GLP compliance:

yes (incl. QA statement)

Limit test:

no

Species:

rat

Strain:

Sprague-Dawley

Sex:

male/female

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Source: Breeder: Charles River Laboratories France, L’Arbresle, France
- Age at study initiation: at the beginning of the treatment period, the males were approximately 10 weeks old
- Mean body weight at study initiation: the males had a mean body weight of 397 g (range: 354 g to 427 g) and the females were approximately
9 weeks old and had a mean body weight of 213 g (range: 183 g to 234 g)
- Fasting period before study: no
- Housing: individually housed, except during pairing, in wire-mesh cages
- Diet: SSNIFF R/M-H pelleted diet (free access)
- Water: tap water filtered with a 0.22 µm filter (free access)
- Acclimation period: at least 7 days before the beginning of the study.

ENVIRONMENTAL CONDITIONS
- Temperature (°C): 22 ± 2°C
- Humidity (%): 50 ± 20%
- Air changes (per hr): approximately 12 cycles/hour of filtered, non-recycled air
- Photoperiod (hrs dark / hrs light): 12 h/12 h (7:00 - 19:00).

IN-LIFE DATES: 05 April 2011 to 17 October 2011.

Route of administration:

oral: gavage

Vehicle:

other: water drinking water (treated by reverse osmosis)

Details on oral exposure:

PREPARATION OF DOSING SOLUTIONS:
Dose-levels were calculated in terms of 2-[(1-methylpropyl)amino]ethanol (CAS No. 35265-04-4) which is the form supplied by the Sponsor: there was no correction
factor.

The test item was administered as a solution in the vehicle. The formulations were stirred for 30 minutes in order to ensure the solubilisation of the
test item in the vehicle. No aluminium equipment was used for the preparation of the dosage forms.
The test item dosage forms were prepared on a weekly basis, stored at room temperature prior to use and delivered in brown flasks.

VEHICLE
- Concentration in vehicle: 1, 5 and 10 mg/mL
- Amount of vehicle (if gavage): 10 mL/kg/day.

Analytical verification of doses or concentrations:

yes

Details on analytical verification of doses or concentrations:

Type of method: High Performance Liquid Chromatography with tandem Mass Spectrometry detection (LC/MS MS) analytical method for the determination of 2-[(1-methylpropyl)amino]ethanol in dosage form samples was used.
Test item concentrations: the test item concentrations in the administered dosage forms analyzed in weeks 1, 5 and 7 remained within an acceptable range of -1.2% to +4.2% when compared to the nominal values (± 10%) on a weekly basis according to a stability (CIT/Study No. 37512 AHS).

Duration of treatment / exposure:

In the males:
− 2 weeks before mating,
− during the mating period (up to 3 weeks),
− until sacrifice (i.e. at least 5 weeks in total),

In the females:
− 2 weeks before mating,
− during the mating period (up to 3 weeks),
− during pregnancy,
− during lactation until day 4 post-partum inclusive,
− until sacrifice for females which had not delivered (day 25 p.c.).

Frequency of treatment:

Daily.

Remarks:

Doses / Concentrations:
10, 50 and 100 mg/kg/day
Basis:
actual ingested

No. of animals per sex per dose:

10

Control animals:

yes, concurrent vehicle

Details on study design:

- Dose selection rationale:
The dose-levels were selected in agreement with the Sponsor based on the results of the CIT/Study No. 37513 TSR.

- Rationale for animal assignment: computerized stratification procedure.

Observations and examinations performed and frequency:

CAGE SIDE OBSERVATIONS:
- Time schedule: at least twice a day during the treatment period.

DETAILED CLINICAL OBSERVATIONS:
- Time schedule: once a day during the treatment period.

BODY WEIGHT (GAIN):
- Time schedule: Males: on the first day of treatment, then once a week until sacrifice. Females: on the first day of treatment, then once a week until mating (or until sacrifice), on Days 0, 7, 14 and 20 post-coitum and days 1 and 5 post-partum.

FOOD CONSUMPTION:
- Time schedule: once a week until sacrifice, with the exception of the mating period (not recorded).

FOOD EFFICIENCY: No

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

OPHTHALMOSCOPIC EXAMINATION: No

HAEMATOLOGY: No

CLINICAL CHEMISTRY: No

URINALYSIS: No

NEUROBEHAVIOURAL EXAMINATION: No

Sacrifice and pathology:

SACRIFICE
The males were sacrificed after at least 5 weeks of treatment. The body and selected organs were weighed and a complete macroscopic post-mortem examination was performed. A microscopic examination was performed on the kidneys, stomach with forestomach, epididymis, testes and thymus
from the males in the control- and high dose groups, liver from all groups and and on all macroscopic lesions.

The dams were sacrificed on day 5 p.p., the body and selected organs were weighed and a complete macroscopic examination was performed.
A microscopic examination was performed on the kidneys and the stomach with forestomach, in the control and high-dose groups and, on the liver, ovaries (with oviducts) and thymus in all groups and on all macroscopic lesions.

GROSS NECROPSY
On completion of the treatment period all surviving F0 males and females were deeply anesthetized by an intraperitoneal injection of sodium
pentobarbital and sacrificed by exsanguination.
- males: after the end of the pairing period (at least 5 weeks of treatment in total),
- females: on day 5 p.p.,
- females which had not delivered: on day 25 p.c. (after a body weight recording to check for a possible un-noticed delivery),
- mothers with litter dying entirely: as appropriate.

HISTOPATHOLOGY
A microscopic examination was performed on:
- all tissues listed in the tissue procedure table in the males and females of the control- and high-dose groups (groups 1 and 4) sacrificed at the end of the treatment period and for female that were sacrificed prematurely,
- all macroscopic lesions of all the animals of the low- and intermediate-dose groups (groups 2 and 3) sacrificed on completion of the treatment
period,
- thymus of males from control and high-dose groups (groups 1 and 4) and thymus of females from control, low-, mid- and high-dose groups
(groups 1 to 4),
- all females sacrificed because of no delivery to investigate possible causes.

Special emphasis was paid to the stages of spermatogenesis in the male gonads and histopathology of interstitial testicular cell structure.

At the request of by the Sponsor and based upon the microscopic results of the high-dose group, liver and ovaries (with oviducts) of the low- and
intermediate-dose groups were examined.

ORGAN WEIGHTS:
The body weight of each animal sacrificed as scheduled was recorded before sacrifice, and the organs specified in the Tissue Procedure Table were
weighed (wet) as soon as possible after dissection.
The ratio of organ weight to body weight (recorded immediately before sacrifice) was calculated.

Statistics:

Data are compared by one-way analysis of variances and Dunnett test (mean values being considered as normally distributed, variances being considered as homogenous) or by Fischer exact probability test (proportions).

Clinical signs:

no effects observed

Mortality:

no mortality observed

Body weight and weight changes:

effects observed, treatment-related

Description (incidence and severity):

at 100 mg/kg bw/d in females during pregnancy period

Food consumption and compound intake (if feeding study):

effects observed, treatment-related

Description (incidence and severity):

at 100 mg/kg bw/d in females during pregnancy period

Food efficiency:

not examined

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

not examined

Ophthalmological findings:

not examined

Haematological findings:

not examined

Clinical biochemistry findings:

not examined

Urinalysis findings:

not examined

Behaviour (functional findings):

not examined

Organ weight findings including organ / body weight ratios:

effects observed, treatment-related

Description (incidence and severity):

at 100 mg/kg bw/d in females

Gross pathological findings:

no effects observed

Histopathological findings: non-neoplastic:

effects observed, treatment-related

Description (incidence and severity):

at 100 mg/kg bw/d in females

Histopathological findings: neoplastic:

not examined

Details on results:

MORTALITY:
There were no unscheduled deaths.

CLINICAL SIGNS:
Males
There were no treatment-related clinical signs.
The few isolated observations (soft feces, chromodacryorrhea, cutaneous lesion or area of air loss) recorded in controls or treated groups are commonly observed in this species and strain.

Females (premating period)
There were no findings during the premating period.

Females (pregnancy period)
There were no treatment-related clinical signs.
One out of 10 and 6/10 females in the 50 and 100 mg/kg/day groups, respectively, were sacrificed for absence of delivery on day 25 p.c..
All females that did not deliver were pregnant with the exception of one high-dose animal.
An isolated observation (soft feces) recorded in the 10 mg/kg/day group is commonly observed in this species and strain.

Females (lactation period)
There were no treatment-related clinical signs at 10 and 50 mg/kg/day.
One out of four females in the 100 mg/kg/day group with a dead litter was prematurely sacrificed on day 3 p.p..

BODY WEIGHT (GAIN):
Males
There were no treatment-related effects on mean body weights or mean body weight changes.
Isolated reductions in mean body weight were recorded on study day 15 (-7.0% vs. controls, p<0.05) and study day 22 (-6.7% vs. controls, p<0.05) in animals treated at 10 mg/kg/day. In absence of a dose-relationship, an association with the treatment by the test item was considered unlikely.
Isolated reductions or increases in mean body weight change were recorded on periods of days 1 to 8 (-31.0% vs. controls, p<0.05) and 8 to 15
(-41.4% vs. controls, p<0.05) at 10 mg/kg/day or on period of days 22 to 29 at 50 or 100 mg/kg/day (+64.7% and +52.9% vs. controls, p<0.05).
In absence of a dose-relationship, an association with the treatment by the test item was considered unlikely.

Females (premating period)
There were no effects on mean body weight or mean body weight change during the premating period.

Females (pregnancy period)
On day 20 p.c. and at 100 mg/kg/day, there was a statistically significant reduction in mean body weight (-21.3% vs. controls, p<0.001).
Mean body weight change was also markedly reduced at 100 mg/kg/day on periods of days 7 to 14 (-33.3% vs. controls, p<0.05) and on periods of days 14 to 20 p.c. ( 92.4% vs. controls, p<0.001), resulting in an overall reduction of -55.6% vs. controls (p<0.001) on period of days 0 to 20 p.c..
Taking into account both the amplitude of the effects and their presence in the high-dose group only, these finding were considered to be related to the treatment by the test item.

Females (lactation period)
There were no significant effects on mean body weight during the lactation period. However, mean body weight change was reduced in the three remaining dams treated at 100 mg/kg/day on periods of days 1 to 5 p.p. ( 68.2% vs. controls, p<0.01). It was correlated with lower food consumption at this dose-level.

FOOD CONSUMPTION:
Males
There were no treatment-related effects on mean food consumption.

Females (premating period)
There were no effects on mean food consumption during the premating period.

Females (pregnancy period)
There were no effects on mean food consumption during the pregnancy period up to 50 mg/kg/day.
At 100 mg/kg/day, mean food consumption was reduced on days 14 to 20 (-16.1 vs. controls, p<0.05). This effect was considered to be related to the treatment by the test item.

Females (lactation period)
There was a lower mean food consumption in the three remaining dams treated at 100 mg/kg/day on period of days 1 to 5 p.p. (37.2% vs. controls,
p<0.001). This effect was probably secondary to the low number of suckling pups.

ORGAN WEIGHTS:
Treatment-related lower mean absolute and relative liver weights were noted at 100 mg/kg/day, females being more affected than males. It correlated microscopically with lower glycogen content in hepatocytes of treated animals.
High absolute and relative mean thymus weights were noted in females given the test item at 100 mg/kg/day. In the absence of microscopic correlates, a relationship to treatment was ruled out.

GROSS PATHOLOGY:
No treatment-related macroscopic changes were noted in males and females given the test item.
The few macroscopic findings noted at the end of the treatment period were of those commonly recorded in the Sprague Dawley rat and none were
considered to be related to the test item administration.

HISTOPATHOLOGY:
In the liver, a lower mean glycogen content was observed in males and females given the test item at 100 mg/kg/day. There was a trend to dose-related decreased glycogen storage in females from 10 mg/kg/day. The effect was more severe in males than in females. Taking into account the amplitude of the change, this effect was not considered to be adverse.
Focal to multifocal subcapsular necrosis were observed in the liver of some treated females without dose relationship. As the change was often focal, at minimal severity, and could be observed spontaneously, a relationship to treatment was ruled out.

Reproductive organs
Males
Testes and epididymides were observed microscopically. Qualitative testis staging did not indicate any abnormalities in the integrity of the various cell types present within the different stages of the spermatogenic cycle.

Females
Treatment-related microscopic change was observed in the ovaries of animals given 100 mg/kg/day. It consisted of a higher incidence and severity
of increased size of follicular structures. Follicles were larger, with constant internal cavities (late stage follicles). It was observed in 1/10 control females, 1/10 females given 10 mg/kg/day, 2/10 animals treated at 50 mg/kg/day and 7/10 females given 100 mg/kg/day. Although marginal, the increased incidence and severity of the change in females given 100 mg/kg/day was considered to be likely related to the test item.

Dose descriptor:

NOAEL

Effect level:

50 mg/kg bw/day (actual dose received)

Sex:

female

Basis for effect level:

other: Reduced body weight gain in females during gestation at 100 mg/kg bw/d

Dose descriptor:

NOAEL

Effect level:

>= 100 mg/kg bw/day (actual dose received)

Sex:

male

Basis for effect level:

other: No treatment-related effect was observed in male rats.

Critical effects observed:

not specified

Conclusions:

The test item, Sec-Butyl aminoethanol (99.7% purity), was administered daily by oral gavage to male and female Sprague Dawley rats, for 2 weeks before mating, during mating, gestation and until day 5 post partum, at dose-levels of 10, 50 or 100 mg/kg/day.
At the dose-levels of 10 and 50 mg/kg/day, there was no treatment-related effect.
At the dose-level of 100 mg/kg/day, no treatment-related effect was observed in male rats. Mean body weight gain was markedly reduced during the whole gestation and mean food consumption was reduced on days 14 to 20 of gestation. High absolute and relative mean thymus weights and a higher incidence and severity of increased size of follicular structures in ovaries were noted in females.
Based on the results of this study:
- the No Observed Adverse Effect Level (NOAEL) for parental toxicity was considered to be 50 mg/kg/day (based on the reduced body weight gain in females during gestation).

Executive summary:

The potential toxic effects of the test item, sec-butyl aminoethanol was evaluated following daily oral administration (gavage) to male and female rats from before mating, through mating and gestation and until day 4post-partum (p.p.)(Spezia, 2011a). This study was conducted as a reproduction/developmental screening test according to OECD 421 guideline and GLP.

Three groups of 10 male and 10 female Sprague-Dawley rats received the test item, Sec-Butyl aminoethanol (purity 99.7%), by oral (gavage) administration once a day, 2 weeks before mating, through mating and gestation and until day 4p.p..The dose-levels were 10, 50 or 100 mg/kg/day. Another group of 10 males and 10 females received the vehicle, drinking water treated by reverse osmosis, alone, under the same experimental conditions and acted as a control group. The dosing volume was 10 mL/kg/day. Clinical signs and mortality were checked once and twice a day during the treatment period, respectively. Body weight and food consumption were recorded weekly and at determined intervals for females during gestation and lactation.

The males were sacrificed after at least 5 weeks of treatment. The body and selected organs were weighed and a complete macroscopicpost-mortemexamination was performed. A microscopic examination was performed on the kidneys, stomach with forestomach, epididymis, testes and thymus from the males in the control- and high‑dose groups, liver from all groups and on all macroscopic lesions. The dams were sacrificed on day 5p.p.,the body and selected organs were weighed and a complete macroscopic examination was performed. A microscopic examination was performed on the kidneys and the stomach with forestomach, in the control and high-dose groups and, on the liver, ovaries (with oviducts) and thymus in all groups and on all macroscopic lesions.

There were no unscheduled deaths in males. There were no treatment-related clinical signs in males and in females during the premating, pregnancy or lactation periods. There were no treatment-related effects on mean body weights or mean body weight changes in males and in females during the premating period. In females at 100 mg/kg/day only and on day 20p.c.,there was a markedly and statistically significant reduction in mean body weight (-21.3%vs.controls, p < 0.001). Mean body weight change was also markedly reduced at 100 mg/kg/day on periods of days 7 to 14 (-33.3%vs.controls, p > 0.05) and days 14 to 20p.c.(‑92.4%vs.controls, p < 0.001), resulting in an overall reduction of -55.6%vs.controls (p < 0.001) on period of days 0 to 20p.c.Taking into account both the amplitude of the effects and their presence in the high-dose group only, these finding were considered to be related to the treatment by the test item. There were no treatment-related effects on mean food consumption in male. At 100 mg/kg/day, in females and during the pregnancy period only, mean food consumption was moderately reduced on days 14 to 20 (-16.1vs.controls, p < 0.05). This effect was considered to be related to the treatment by the test item. Treatment-related lower liver weights were noted in males and females at 100 mg/kg/day and correlated microscopically with lower glycogen content in hepatocytes of treated animals. There was a trend to dose-related decreased glycogen storage in females from 10 mg/kg/day. This change was not considered to be adverse. No treatment-related macroscopic changes were noted in males and females (including the prematurely sacrificed one) given the test item. Qualitative testis staging did not indicate any abnormalities in the integrity of the various cell types present within the different stages of the spermatogenic cycle. Treatment-related microscopic increased size of follicular structures was observed in the ovaries of animals given 100 mg/kg/day. Although marginal, the increased incidence and severity of the ovarian change in females given 50 mg/kg/day was considered to be likely related to the test item.

The test item, Sec-Butyl aminoethanol (99.7% purity), was administered daily by oral gavage to male and female Sprague‑Dawley rats, for 2 weeks before mating, during mating, gestation and until day 5post‑partum, at dose-levels of 10, 50 or 100 mg/kg/day.  

At the dose-levels of 10 and 50 mg/kg/day, there was no treatment-related effect.

At the dose-level of 100 mg/kg/day, no treatment-related effect was observed in male rats. Mean body weight gain of females was markedly reduced during the whole gestation and mean food consumption was reduced on days 14 to 20 of gestation. High absolute and relative mean thymus weights and a higher incidence and severity of increased size of follicular structures in ovaries were noted in females.

Based on the results of this study:

. the No Observed Adverse Effect Level (NOAEL) for parental toxicity was considered to be higher than 100 mg/kg/day in males and 50 mg/kg/day in females (based on the reduced body weight gain during gestation).

Endpoint conclusion

Endpoint conclusion:

adverse effect observed

Dose descriptor:

NOAEL

50 mg/kg bw/day

Study duration:

subacute

Species:

rat

Repeated dose toxicity: inhalation - systemic effects

Link to relevant study records

Reference

Endpoint:

short-term repeated dose toxicity: inhalation

Type of information:

experimental study

Adequacy of study:

key study

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: GLP guideline study

Qualifier:

according to guideline

Guideline:

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

Deviations:

no

GLP compliance:

yes

Limit test:

no

Species:

rat

Strain:

other: RccHan: WIST(SPF)

Sex:

male/female

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Source: Harlan Laboratories, B.V., Kreuzelweg 53, 5961 NM Horst / Netherlands
- Age at delivery: 8 weeks
- Weight at Acclimatization:
Males: 211.5 to 240.9 g (± 7%)
Females: 152.4 to 170.6 g (± 6%)
- Fasting period before study: no
- Housing: In groups of five in Makrolon type-4 cages with wire mesh tops and sterilized standard softwood bedding
- Diet: Pelleted standard Harlan Teklad 2914C ad libitum
- Water: Community tap-water ad libitum
- Acclimation period: Eight days under test conditions after health examination. Animals were accustomed to the restraining tubes for 3 daily periods of approximately 1, 2, and 4 hours, respectively.

ENVIRONMENTAL CONDITIONS
- Temperature (°C): 22 ± 3
- Humidity (%): 30 - 70
- Air changes (per hr): 10-15
- Photoperiod (hrs dark / hrs light): 12/12

Route of administration:

inhalation: vapour

Type of inhalation exposure:

other: Inhalation by nose-only, flow-past exposure

Vehicle:

clean air

Remarks on MMAD:

MMAD / GSD: Not feasible for a vapor.

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 1.0 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: Sec-Butyl aminoethanol was pumped into a glass flask. Compressed dried air (approximately 60 L/min) was supplied into the glass flask through a metal nebulization tube. The glass flask was kept within a thermal regulating device set to maintain a temperature in the glass flasks between approximately 90 – 110 °C to facilitate the process of vaporization. The vapor was pumped at the exit of the particle filter. Furthermore, the vapor of the test item of the low, mid and high dose group was achieved by serial dilution with compressed, filtered, dry air of the higher vapor concentration using gas pumps. The concentration of the test item administered to the animal was controlled by regulating the flow of vapor into the inhalation chamber. The generated vapor was diluted as necessary with compressed air to achieve the concentrations required for this study.

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 for the initially generated vapor was measured by weighing the syringe containing the test item solution before and after each exposure to determine the quantity of test item used. The weight of test item used was then divided by the total airflow volume to give the nominal concentration. These data were used only for the purpose of monitoring the performance of the generation system.
- 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
To determine the concentration of the test item in the generated vapor chemical analyses of test atmosphere samples was performed once, twice or three times daily for groups 2, 3 and 4, respectively. Test atmosphere samples were collected in solvent traps with 100 ml Acetonitrile as solvent per trap. Sampling flow was 1 L/min per exposure port. The duration of sampling was between 300 to 330 min for group 2, 120 to 150 min for group 3 and 78 to 95 min for group 4. For each exposure one, two or three samples were collected for groups 2 to 4, respectively, and were transferred into labeled appropriate vials, forwarded on cool packs to the scientist responsible for formulation analysis and stored at 5 ± 3 °C until analysis or were analyzed directly. They were analyzed for the test item by Harlan Laboratories Ltd., Zelgliweg 1, 4452 Itingen / Switzerland using a GC method.
- Oxygen Concentration
The oxygen concentration in the chamber was measured continuously during each exposure using a calibrated device. Additionally, values were recorded hourly during each exposure. The oxygen concentration was maintained above 19% during the exposure period.
- Relative Humidity / Temperature
The relative humidity and temperature in the chamber were measured continuously during each exposure using a calibrated device. Additionally, values were recorded hourly during each exposure.
- Airflow Rate
The exposure airflow rate was adjusted as appropriate before the start of the exposure using calibrated flow-meters. The actual airflow rate was monitored hourly during each exposure.

Analytical verification of doses or concentrations:

yes

Details on analytical verification of doses or concentrations:

see before

Duration of treatment / exposure:

4 weeks

Frequency of treatment:

6 hours/day, 5 days/week at approximately 24-hour intervals.

Remarks:

Doses / Concentrations:
5, 20 and 80 mg/m3
Basis:
other: target conc.

Remarks:

Doses / Concentrations:
5.979 ± 1.641, 21.15 ± 2.657 and 90.48 ± 7.770 mg/m3
Basis:
analytical conc.

No. of animals per sex per dose:

Group 1: 10 males and 10 females
Group 2: 5 males and 5 females
Group 3: 5 males and 5 females
Group 4: 10 males and 10 females

Control animals:

yes, sham-exposed

Details on study design:

- Dose selection rationale: Dosages were selected based on data from the 5-Day dose range finding study.
- Post-exposure recovery period in satellite groups: 4 weeks

Observations and examinations performed and frequency:

CAGE SIDE OBSERVATIONS: Yes
- Time schedule: Twice daily during treatment, once daily during acclimatization and recovery.
- Cage side observations checked in table [No.?] were included.

CLINICAL OBSERVATIONS: Yes
- Time schedule: once daily during treatment (after exposure) and once weekly during acclimatization
and recovery.

BODY WEIGHT: Yes
- Time schedule for examinations: weekly (each individual animal) during acclimatization and recovery and twice weekly during treatment.

FOOD CONSUMPTION: Yes
- Time schedule for examinations: weekly (per cage) during acclimatization, treatment and recovery.

FOOD EFFICIENCY: No

WATER CONSUMPTION: No

OPHTHALMOSCOPIC EXAMINATION: Yes
- Time schedule for examinations: Acclimatization and week 4 of treatment
- Dose groups that were examined: all

HAEMATOLOGY: Yes
- Time schedule for collection of blood: after 4 Weeks
- Anaesthetic used for blood collection: Yes (isoflurane)
- Animals fasted: Yes
- How many animals: all
- The following hematology parameters were determined:
Complete Blood Cell Count
Erythrocyte count
Hemoglobin
Hematocrit
Mean corpuscular volume
Red cell volume distribution width
Mean corpuscular hemoglobin
Mean corpuscular hemoglobin concentration
Hemoglobin concentration distribution width
Reticulocyte count
Reticulocyte maturity index (low, medium,
high fluorescence)
Leukocyte count, total
Differential leukocyte count:
Neutrophils
Eosinophils
Basophils
Lymphocytes
Monocytes
Large unstained cells
Platelet count
Coagulation
Prothrombin time (= Thromboplastin time)
Activated partial Thromboplastin time

CLINICAL CHEMISTRY: Yes / No / No data
- Time schedule for collection of blood: after 4 Weeks
- Animals fasted: Yes
- How many animals: all
- The following clinical biochemistry parameters were determined:
Glucose
Urea
Creatinine
Bilirubin, total
Cholesterol, total
Triglycerides
Phospholipids
Aspartate aminotransferase
Alanine aminotransferase
Lactate dehydrogenase
Alkaline phosphatase
Gamma-glutamyl-transferase
Creatine kinase
Sodium
Potassium
Chloride
Calcium
Phosphorus
Protein, total
Albumin
Globulin
Albumin/Globulin ratio

URINALYSIS: Yes / No / No data
- Time schedule for collection of urine: after 4 Weeks
- Metabolism cages used for collection of urine: Yes
- Animals fasted: Yes
- The following urine parameters were determined:
Physical Examination:
Urine volume (16 hour)
Specific gravity (relative density)
Color
Appearance
Chemical Examination:
pH value
Nitrite
Protein
Glucose
Ketones
Urobilinogen
Bilirubin
Erythrocytes
Leukocytes

NEUROBEHAVIOURAL EXAMINATION: No

Sacrifice and pathology:

GROSS PATHOLOGY: Yes (see table below)

ORGAN WEIGHTS: Yes (see table below)

HISTOPATHOLOGY: Yes (see table below)

Statistics:

The following statistical methods were used to analyze body weight, ophthalmoscopic examinations, macroscopic findings, organ weights and ratios, as well as clinical laboratory data:
• The Dunnett-test (many to one t-test) based on a pooled variance estimate was applied if the variables could be assumed to follow a normal distribution for the comparison of the treated groups and the control groups for each sex.
• The Steel-test (many-one rank test) was applied instead of the Dunnett-test when the data could not be assumed to follow a normal distribution.
• Fisher's exact-test.

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:

no effects observed

Haematological findings:

no effects observed

Clinical biochemistry findings:

no effects observed

Urinalysis findings:

no effects observed

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:

not examined

Details on results:

CLINICAL SIGNS AND MORTALITY
All animals survived the scheduled treatment and recovery periods.
No clinical signs were observed throughout the scheduled treatment and recovery period.

BODY WEIGHT AND WEIGHT GAIN
Slight, but not statistically significant, reductions of the body weight and body weight gain were recorded in the male animals of group 4 from week 2 until the end of the treatment period when compared to the animals of the control group. Normal body weight development was observed in these animals during the recovery period.
Body weight and body weight gain were not affected in the female animals.
Body weight loss or stagnation of the body weight gain during the first few days of inhalation studies is not unusual and is due to the restraining of the anima s in the tube during the nose-only exposure procedure.

FOOD CONSUMPTION
No effect on food consumption was observed in the animals of all groups throughout the treatment and recovery period.

OPHTHALMOSCOPIC EXAMINATION
As ophthalmoscopic findings noted at the end of the treatment period were already noted during acclimatization period they were considered not to be related to the treatment with the test item.

HAEMATOLOGY
There were no test item-related effects in hematology in males and females of all treated groups when compared to the control group.
Some inter-group variations occasionally achieved statistical significance but did not show a dose-relationship, were within the historical control range or were considered to be of normal biological variation. Therefore they were considered not to be related to treatment with the test item and are not discussed further.

CLINICAL CHEMISTRY
No effects on clinical biochemistry parameters were observed in males and females of the treated groups when compared to the control group.
Some inter-group variations occasionally achieved statistical significance but did not show a dose-relationship, were within the historical control range or were considered to be of normal biological variation and were therefore considered not to be related to treatment with the test item.

URINALYSIS
Urinalysis parameters remained unaffected by the treatment with the test item in males and females when compared to the control group.

ORGAN WEIGHTS
Organ weights of the animals treated with the test item were not different from those of the control group.

GROSS PATHOLOGY
There were no macroscopic findings during necropsy that were considered to be related to treatment with the test item.
All findings were considered to be incidental findings commonly noted in rats of this strain and age and were therefore considered not to be related to treatment with the test item.

HISTOPATHOLOGY: NON-NEOPLASTIC
Minimal focal olfactory mucosa epithelial degeneration was observed at the dorsal meatus of the nasal cavity level 2 in only one male treated with 80 µg Sec-Butyl aminoethanol 2-[(1-methylpropyl)amino]ethanol /L air (group 4) after the end of the treatment period (allocation A). A minimal focal change consisting of regenerative epithelium of the nasal cavity level 3 was noticed in one male and one female of the high dose group after the end of the recovery period (allocation B). The lesions were found either on the septum or at a turbinate tip.
The remainder of findings recorded was within the range of normal background lesions which may be recorded in animals of this strain and age.

Dose descriptor:

NOAEC

Remarks:

nasal irritation

Effect level:

21 mg/m³ air (analytical)

Sex:

male/female

Dose descriptor:

NOAEC

Remarks:

systemic toxicity

Effect level:

> 90 mg/m³ air (analytical)

Sex:

male/female

Critical effects observed:

not specified

Table1      Incidence and Mean Severity of Main Findings in Nasal Cavities

Main Study Animals (Allocation A) Nasal Cavity Level 2
Finding / Groups	1		2		3		4
Total Affected / Mean Severity	(5) M	(5) F	(5) M	(5) F	(5) M	(5) F	(5) M	(5) F
Epithelial Degeneration	0	0	0	0	0	0	1/1.0	0
Recovery Animals (Allocation B) Nasal Cavity Level 3
Finding / Groups	1		2		3		4
Total Affected / Mean Severity	(5) M	(5) F	0	0	0	0	(5) M	(5) F
Epithelial Degeneration, Regenerative	0	0	-	-	-	-	1/1.0	1/1.0

 

Conclusions:

Daily exposure of Wistar rats to target vapor concentrations of 5, 20 and 80 µg/L Sec-Butyl aminoethanol over a period of 5 days/week for 4 consecutive weeks resulted in slight and transient effects on body weight and in minor primary changes in the nasal cavities.
Minimal effects on body weight were observed in the males of the high dose group, only, and were not present after the end of the recovery period.

Test item-related histopathologic findings were limited to nasal cavity levels 2 and 3 and consisted of minimal focal olfactory mucosa epithelial degeneration at the dorsal meatus in one high dose male after 4 weeks of treatment and of a minimal focal change consisting of regenerative epithelium in one male and female, each, of the high dose group after 4 weeks of recovery. The lesions were found either on the septum or at a turbinate tip. In accordance to these findings the nasal cavities were considered to be the target organ for the exposure to Sec-Butyl aminoethanol
There were no further findings related to treatment with Sec-Butyl aminoethanol which were considered to be of toxicological relevance.
Based on the histopathological results in this study the mid concentration of 20 µg Sec-Butyl aminoethanol /L air was considered to be the No-Observed Adverse Effect Concentration (NOAEC) for the nasal irritation. The high concentration of 80 µg Sec-Butyl aminoethanol /L air was considered to be the NOAEC for the systemic toxicity.

Executive summary:

In a 4-week inhalation toxicity study Sec-Butyl aminoethanol was administered 6 hours daily to rats by nose-only, flow-past inhalation exposure for a period of 5 days/week for 4 consecutive weeks. The reversibility or progression of any test item related effects or any delayed toxicity was assessed during a 4-week treatment free recovery period following the treatment period. The study comprised 5 male and 5 female Wistar rats in each group and additionally 5 male and 5 female rats in groups 1 and 4 for recovery. The rats of the control group 1 were exposed to air. Groups 2 to 4 were exposed to target concentrations of 5, 20 and 80 μg/L Sec-Butyl aminoethanol respectively. Throughout the study all animals were observed for viability and mortality, clinical signs, body weights, food consumption, ophthalmoscopy, clinical laboratory investigations, organ weights and macroscopic findings were recorded. A histopathologic examination was also performed. The study was performed in accordance with the procedures indicated by the OECD Guideline for the Testing of Chemicals, Number 412, September 7, 2009 "Subacute Inhalation Toxicity: 28-Day Study" and in compliance with Good Laboratory Practice. Exposure to chemically determined vapor concentrations of 5.98, 21.2 and 90.5 μg/L Sec-Butyl aminoethanol were achieved in groups 2 to 4, respectively, and were slight to moderately above the respective targets. Temperature, relative humidity and oxygen concentration during exposure were considered to be suitable for this type of study. All animals survived and no clinical signs were observed during the scheduled treatment and recovery period. Slight, but not statistically significant, reductions of the body weight and body weight gain were recorded in the males of group 4 from week 2 until the end of the treatment period and returned to normal during the recovery period. Body weight in females was not affected. There was no effect on food consumption. No test item-related findings were recorded in ophthalmoscopy. Parameters in hematology, clinical biochemistry and urinalysis remained unaffected. There was no effect on organ weight. No test item-related macroscopic findings were recorded during necropsy. Microscopic findings consisted of minimal focal olfactory mucosa epithelial degeneration at the dorsal meatus of the nasal cavity level 2 in one high dose male (allocation A) and of a minimal focal change consisting of regenerative epithelium of the nasal cavity level 3 in one male and one female of the high dose group (allocation B). Lesions were found either on the septum or at a turbinate tip.

In accordance to the findings above the nasal cavities were considered to be the target organ for the exposure to Sec-Butyl aminoethanol. Based on the histopathological results in this study the mid concentration of 21 μg Sec-Butyl

aminoethanol /L air was considered to be the No-Observed Adverse Effect Concentration (NOAEC) for the nasal irritation. The high concentration of 90 μg Sec-Butyl aminoethanol /L air was considered to be the NOAEC for the systemic toxicity.

Endpoint conclusion

Endpoint conclusion:

no adverse effect observed

Dose descriptor:

NOAEC

90 mg/m³

Study duration:

subacute

Species:

rat

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:

key study

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: GLP guideline study

Qualifier:

according to guideline

Guideline:

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

Deviations:

no

GLP compliance:

yes

Limit test:

no

Species:

rat

Strain:

other: RccHan: WIST(SPF)

Sex:

male/female

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Source: Harlan Laboratories, B.V., Kreuzelweg 53, 5961 NM Horst / Netherlands
- Age at delivery: 8 weeks
- Weight at Acclimatization:
Males: 211.5 to 240.9 g (± 7%)
Females: 152.4 to 170.6 g (± 6%)
- Fasting period before study: no
- Housing: In groups of five in Makrolon type-4 cages with wire mesh tops and sterilized standard softwood bedding
- Diet: Pelleted standard Harlan Teklad 2914C ad libitum
- Water: Community tap-water ad libitum
- Acclimation period: Eight days under test conditions after health examination. Animals were accustomed to the restraining tubes for 3 daily periods of approximately 1, 2, and 4 hours, respectively.

ENVIRONMENTAL CONDITIONS
- Temperature (°C): 22 ± 3
- Humidity (%): 30 - 70
- Air changes (per hr): 10-15
- Photoperiod (hrs dark / hrs light): 12/12

Route of administration:

inhalation: vapour

Type of inhalation exposure:

other: Inhalation by nose-only, flow-past exposure

Vehicle:

clean air

Remarks on MMAD:

MMAD / GSD: Not feasible for a vapor.

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 1.0 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: Sec-Butyl aminoethanol was pumped into a glass flask. Compressed dried air (approximately 60 L/min) was supplied into the glass flask through a metal nebulization tube. The glass flask was kept within a thermal regulating device set to maintain a temperature in the glass flasks between approximately 90 – 110 °C to facilitate the process of vaporization. The vapor was pumped at the exit of the particle filter. Furthermore, the vapor of the test item of the low, mid and high dose group was achieved by serial dilution with compressed, filtered, dry air of the higher vapor concentration using gas pumps. The concentration of the test item administered to the animal was controlled by regulating the flow of vapor into the inhalation chamber. The generated vapor was diluted as necessary with compressed air to achieve the concentrations required for this study.

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 for the initially generated vapor was measured by weighing the syringe containing the test item solution before and after each exposure to determine the quantity of test item used. The weight of test item used was then divided by the total airflow volume to give the nominal concentration. These data were used only for the purpose of monitoring the performance of the generation system.
- 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
To determine the concentration of the test item in the generated vapor chemical analyses of test atmosphere samples was performed once, twice or three times daily for groups 2, 3 and 4, respectively. Test atmosphere samples were collected in solvent traps with 100 ml Acetonitrile as solvent per trap. Sampling flow was 1 L/min per exposure port. The duration of sampling was between 300 to 330 min for group 2, 120 to 150 min for group 3 and 78 to 95 min for group 4. For each exposure one, two or three samples were collected for groups 2 to 4, respectively, and were transferred into labeled appropriate vials, forwarded on cool packs to the scientist responsible for formulation analysis and stored at 5 ± 3 °C until analysis or were analyzed directly. They were analyzed for the test item by Harlan Laboratories Ltd., Zelgliweg 1, 4452 Itingen / Switzerland using a GC method.
- Oxygen Concentration
The oxygen concentration in the chamber was measured continuously during each exposure using a calibrated device. Additionally, values were recorded hourly during each exposure. The oxygen concentration was maintained above 19% during the exposure period.
- Relative Humidity / Temperature
The relative humidity and temperature in the chamber were measured continuously during each exposure using a calibrated device. Additionally, values were recorded hourly during each exposure.
- Airflow Rate
The exposure airflow rate was adjusted as appropriate before the start of the exposure using calibrated flow-meters. The actual airflow rate was monitored hourly during each exposure.

Analytical verification of doses or concentrations:

yes

Details on analytical verification of doses or concentrations:

see before

Duration of treatment / exposure:

4 weeks

Frequency of treatment:

6 hours/day, 5 days/week at approximately 24-hour intervals.

Remarks:

Doses / Concentrations:
5, 20 and 80 mg/m3
Basis:
other: target conc.

Remarks:

Doses / Concentrations:
5.979 ± 1.641, 21.15 ± 2.657 and 90.48 ± 7.770 mg/m3
Basis:
analytical conc.

No. of animals per sex per dose:

Group 1: 10 males and 10 females
Group 2: 5 males and 5 females
Group 3: 5 males and 5 females
Group 4: 10 males and 10 females

Control animals:

yes, sham-exposed

Details on study design:

- Dose selection rationale: Dosages were selected based on data from the 5-Day dose range finding study.
- Post-exposure recovery period in satellite groups: 4 weeks

Observations and examinations performed and frequency:

CAGE SIDE OBSERVATIONS: Yes
- Time schedule: Twice daily during treatment, once daily during acclimatization and recovery.
- Cage side observations checked in table [No.?] were included.

CLINICAL OBSERVATIONS: Yes
- Time schedule: once daily during treatment (after exposure) and once weekly during acclimatization
and recovery.

BODY WEIGHT: Yes
- Time schedule for examinations: weekly (each individual animal) during acclimatization and recovery and twice weekly during treatment.

FOOD CONSUMPTION: Yes
- Time schedule for examinations: weekly (per cage) during acclimatization, treatment and recovery.

FOOD EFFICIENCY: No

WATER CONSUMPTION: No

OPHTHALMOSCOPIC EXAMINATION: Yes
- Time schedule for examinations: Acclimatization and week 4 of treatment
- Dose groups that were examined: all

HAEMATOLOGY: Yes
- Time schedule for collection of blood: after 4 Weeks
- Anaesthetic used for blood collection: Yes (isoflurane)
- Animals fasted: Yes
- How many animals: all
- The following hematology parameters were determined:
Complete Blood Cell Count
Erythrocyte count
Hemoglobin
Hematocrit
Mean corpuscular volume
Red cell volume distribution width
Mean corpuscular hemoglobin
Mean corpuscular hemoglobin concentration
Hemoglobin concentration distribution width
Reticulocyte count
Reticulocyte maturity index (low, medium,
high fluorescence)
Leukocyte count, total
Differential leukocyte count:
Neutrophils
Eosinophils
Basophils
Lymphocytes
Monocytes
Large unstained cells
Platelet count
Coagulation
Prothrombin time (= Thromboplastin time)
Activated partial Thromboplastin time

CLINICAL CHEMISTRY: Yes / No / No data
- Time schedule for collection of blood: after 4 Weeks
- Animals fasted: Yes
- How many animals: all
- The following clinical biochemistry parameters were determined:
Glucose
Urea
Creatinine
Bilirubin, total
Cholesterol, total
Triglycerides
Phospholipids
Aspartate aminotransferase
Alanine aminotransferase
Lactate dehydrogenase
Alkaline phosphatase
Gamma-glutamyl-transferase
Creatine kinase
Sodium
Potassium
Chloride
Calcium
Phosphorus
Protein, total
Albumin
Globulin
Albumin/Globulin ratio

URINALYSIS: Yes / No / No data
- Time schedule for collection of urine: after 4 Weeks
- Metabolism cages used for collection of urine: Yes
- Animals fasted: Yes
- The following urine parameters were determined:
Physical Examination:
Urine volume (16 hour)
Specific gravity (relative density)
Color
Appearance
Chemical Examination:
pH value
Nitrite
Protein
Glucose
Ketones
Urobilinogen
Bilirubin
Erythrocytes
Leukocytes

NEUROBEHAVIOURAL EXAMINATION: No

Sacrifice and pathology:

GROSS PATHOLOGY: Yes (see table below)

ORGAN WEIGHTS: Yes (see table below)

HISTOPATHOLOGY: Yes (see table below)

Statistics:

The following statistical methods were used to analyze body weight, ophthalmoscopic examinations, macroscopic findings, organ weights and ratios, as well as clinical laboratory data:
• The Dunnett-test (many to one t-test) based on a pooled variance estimate was applied if the variables could be assumed to follow a normal distribution for the comparison of the treated groups and the control groups for each sex.
• The Steel-test (many-one rank test) was applied instead of the Dunnett-test when the data could not be assumed to follow a normal distribution.
• Fisher's exact-test.

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:

no effects observed

Haematological findings:

no effects observed

Clinical biochemistry findings:

no effects observed

Urinalysis findings:

no effects observed

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:

not examined

Details on results:

CLINICAL SIGNS AND MORTALITY
All animals survived the scheduled treatment and recovery periods.
No clinical signs were observed throughout the scheduled treatment and recovery period.

BODY WEIGHT AND WEIGHT GAIN
Slight, but not statistically significant, reductions of the body weight and body weight gain were recorded in the male animals of group 4 from week 2 until the end of the treatment period when compared to the animals of the control group. Normal body weight development was observed in these animals during the recovery period.
Body weight and body weight gain were not affected in the female animals.
Body weight loss or stagnation of the body weight gain during the first few days of inhalation studies is not unusual and is due to the restraining of the anima s in the tube during the nose-only exposure procedure.

FOOD CONSUMPTION
No effect on food consumption was observed in the animals of all groups throughout the treatment and recovery period.

OPHTHALMOSCOPIC EXAMINATION
As ophthalmoscopic findings noted at the end of the treatment period were already noted during acclimatization period they were considered not to be related to the treatment with the test item.

HAEMATOLOGY
There were no test item-related effects in hematology in males and females of all treated groups when compared to the control group.
Some inter-group variations occasionally achieved statistical significance but did not show a dose-relationship, were within the historical control range or were considered to be of normal biological variation. Therefore they were considered not to be related to treatment with the test item and are not discussed further.

CLINICAL CHEMISTRY
No effects on clinical biochemistry parameters were observed in males and females of the treated groups when compared to the control group.
Some inter-group variations occasionally achieved statistical significance but did not show a dose-relationship, were within the historical control range or were considered to be of normal biological variation and were therefore considered not to be related to treatment with the test item.

URINALYSIS
Urinalysis parameters remained unaffected by the treatment with the test item in males and females when compared to the control group.

ORGAN WEIGHTS
Organ weights of the animals treated with the test item were not different from those of the control group.

GROSS PATHOLOGY
There were no macroscopic findings during necropsy that were considered to be related to treatment with the test item.
All findings were considered to be incidental findings commonly noted in rats of this strain and age and were therefore considered not to be related to treatment with the test item.

HISTOPATHOLOGY: NON-NEOPLASTIC
Minimal focal olfactory mucosa epithelial degeneration was observed at the dorsal meatus of the nasal cavity level 2 in only one male treated with 80 µg Sec-Butyl aminoethanol 2-[(1-methylpropyl)amino]ethanol /L air (group 4) after the end of the treatment period (allocation A). A minimal focal change consisting of regenerative epithelium of the nasal cavity level 3 was noticed in one male and one female of the high dose group after the end of the recovery period (allocation B). The lesions were found either on the septum or at a turbinate tip.
The remainder of findings recorded was within the range of normal background lesions which may be recorded in animals of this strain and age.

Dose descriptor:

NOAEC

Remarks:

nasal irritation

Effect level:

21 mg/m³ air (analytical)

Sex:

male/female

Dose descriptor:

NOAEC

Remarks:

systemic toxicity

Effect level:

> 90 mg/m³ air (analytical)

Sex:

male/female

Critical effects observed:

not specified

Table1      Incidence and Mean Severity of Main Findings in Nasal Cavities

Main Study Animals (Allocation A) Nasal Cavity Level 2
Finding / Groups	1		2		3		4
Total Affected / Mean Severity	(5) M	(5) F	(5) M	(5) F	(5) M	(5) F	(5) M	(5) F
Epithelial Degeneration	0	0	0	0	0	0	1/1.0	0
Recovery Animals (Allocation B) Nasal Cavity Level 3
Finding / Groups	1		2		3		4
Total Affected / Mean Severity	(5) M	(5) F	0	0	0	0	(5) M	(5) F
Epithelial Degeneration, Regenerative	0	0	-	-	-	-	1/1.0	1/1.0

 

Conclusions:

Daily exposure of Wistar rats to target vapor concentrations of 5, 20 and 80 µg/L Sec-Butyl aminoethanol over a period of 5 days/week for 4 consecutive weeks resulted in slight and transient effects on body weight and in minor primary changes in the nasal cavities.
Minimal effects on body weight were observed in the males of the high dose group, only, and were not present after the end of the recovery period.

Test item-related histopathologic findings were limited to nasal cavity levels 2 and 3 and consisted of minimal focal olfactory mucosa epithelial degeneration at the dorsal meatus in one high dose male after 4 weeks of treatment and of a minimal focal change consisting of regenerative epithelium in one male and female, each, of the high dose group after 4 weeks of recovery. The lesions were found either on the septum or at a turbinate tip. In accordance to these findings the nasal cavities were considered to be the target organ for the exposure to Sec-Butyl aminoethanol
There were no further findings related to treatment with Sec-Butyl aminoethanol which were considered to be of toxicological relevance.
Based on the histopathological results in this study the mid concentration of 20 µg Sec-Butyl aminoethanol /L air was considered to be the No-Observed Adverse Effect Concentration (NOAEC) for the nasal irritation. The high concentration of 80 µg Sec-Butyl aminoethanol /L air was considered to be the NOAEC for the systemic toxicity.

Executive summary:

In a 4-week inhalation toxicity study Sec-Butyl aminoethanol was administered 6 hours daily to rats by nose-only, flow-past inhalation exposure for a period of 5 days/week for 4 consecutive weeks. The reversibility or progression of any test item related effects or any delayed toxicity was assessed during a 4-week treatment free recovery period following the treatment period. The study comprised 5 male and 5 female Wistar rats in each group and additionally 5 male and 5 female rats in groups 1 and 4 for recovery. The rats of the control group 1 were exposed to air. Groups 2 to 4 were exposed to target concentrations of 5, 20 and 80 μg/L Sec-Butyl aminoethanol respectively. Throughout the study all animals were observed for viability and mortality, clinical signs, body weights, food consumption, ophthalmoscopy, clinical laboratory investigations, organ weights and macroscopic findings were recorded. A histopathologic examination was also performed. The study was performed in accordance with the procedures indicated by the OECD Guideline for the Testing of Chemicals, Number 412, September 7, 2009 "Subacute Inhalation Toxicity: 28-Day Study" and in compliance with Good Laboratory Practice. Exposure to chemically determined vapor concentrations of 5.98, 21.2 and 90.5 μg/L Sec-Butyl aminoethanol were achieved in groups 2 to 4, respectively, and were slight to moderately above the respective targets. Temperature, relative humidity and oxygen concentration during exposure were considered to be suitable for this type of study. All animals survived and no clinical signs were observed during the scheduled treatment and recovery period. Slight, but not statistically significant, reductions of the body weight and body weight gain were recorded in the males of group 4 from week 2 until the end of the treatment period and returned to normal during the recovery period. Body weight in females was not affected. There was no effect on food consumption. No test item-related findings were recorded in ophthalmoscopy. Parameters in hematology, clinical biochemistry and urinalysis remained unaffected. There was no effect on organ weight. No test item-related macroscopic findings were recorded during necropsy. Microscopic findings consisted of minimal focal olfactory mucosa epithelial degeneration at the dorsal meatus of the nasal cavity level 2 in one high dose male (allocation A) and of a minimal focal change consisting of regenerative epithelium of the nasal cavity level 3 in one male and one female of the high dose group (allocation B). Lesions were found either on the septum or at a turbinate tip.

In accordance to the findings above the nasal cavities were considered to be the target organ for the exposure to Sec-Butyl aminoethanol. Based on the histopathological results in this study the mid concentration of 21 μg Sec-Butyl

aminoethanol /L air was considered to be the No-Observed Adverse Effect Concentration (NOAEC) for the nasal irritation. The high concentration of 90 μg Sec-Butyl aminoethanol /L air was considered to be the NOAEC for the systemic toxicity.

Endpoint conclusion

Endpoint conclusion:

adverse effect observed

Dose descriptor:

NOAEC

21 mg/m³

Study duration:

subacute

Species:

rat

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

Inhalation route

In a 4-week inhalation toxicity study Sec-Butyl aminoethanol was administered 6 hours daily to rats by nose-only, flow-past inhalation exposure for a period of 5 days/week for 4 consecutive weeks (Woyda, 2013a). The reversibility or progression of any test item related effects or any delayed toxicity was assessed during a 4-week treatment free recovery period following the treatment period. The study comprised 5 male and 5 female Wistar rats in each group and additionally 5 male and 5 female rats in groups 1 and 4 for recovery. The rats of the control group 1 were exposed to air. Groups 2 to 4 were exposed to target concentrations of 5, 20 and 80 mg/m3 Sec-Butyl aminoethanol respectively. Throughout the study all animals were observed for viability and mortality, clinical signs, body weights, food consumption, ophthalmoscopy, clinical laboratory investigations, organ weights and macroscopic findings were recorded. A histopathologic examination was also performed. The study was performed in accordance with the procedures indicated by the OECD Guideline for the Testing of Chemicals, Number 412, September 7, 2009 "Subacute Inhalation Toxicity: 28-Day Study" and in compliance with Good Laboratory Practice. Exposure to chemically determined vapor concentrations of 5.98, 21.2 and 90.5 mg/m3 Sec-Butyl aminoethanol were achieved in groups 2 to 4, respectively, and were slight to moderately above the respective targets. Temperature, relative humidity and oxygen concentration during exposure were considered to be suitable for this type of study. All animals survived and no clinical signs were observed during the scheduled treatment and recovery period. Slight, but not statistically significant, reductions of the body weight and body weight gain were recorded in the males of group 4 from week 2 until the end of the treatment period and returned to normal during the recovery period. Body weight in females was not affected. There was no effect on food consumption. No test item-related findings were recorded in ophthalmoscopy. Parameters in hematology, clinical biochemistry and urinalysis remained unaffected. There was no effect on organ weight. No test item-related macroscopic findings were recorded during necropsy. Microscopic findings consisted of minimal focal olfactory mucosa epithelial degeneration at the dorsal meatus of the nasal cavity level 2 in one high dose male (allocation A) and of a minimal focal change consisting of regenerative epithelium of the nasal cavity level 3 in one male and one female of the high dose group (allocation B). Lesions were found either on the septum or at a turbinate tip. n accordance to the findings above the nasal cavities were considered to be the target organ for the exposure to Sec-Butyl aminoethanol . Based on the histopathological results in this study the mid concentration of 21 mg/m3 air was considered to be the No-Observed Adverse Effect Concentration (NOAEC) for the nasal irritation. The high concentration of 90 mg/m3 air was considered to be the NOAEC for the systemic toxicity.

In a dose range finding study Sec-Butyl aminoethanol was administered to Wistar rats by nose-only, flow-past inhalation for a period of five days (6 hours/day) (Woyda, 2013b). The study comprised four groups each containing five male and five female rats. The animals of the control group (group 1) were exposed to air. The other groups (groups 2, 3 and 4) were exposed to 28, 91 and 281 mg/m3 sec-Butyl aminoethanol respectively. The chemically determined vapor concentrations were slightly below the respective targets. Throughout the study all animals were observed for mortality, clinical signs, body weights, food consumption, organ weights and macroscopic findings were recorded. A histopathologic examination was also performed. All animals survived the scheduled treatment period of the study. Clinical signs consisted of slight reddish nasal secretion after exposure in males of group 4 on day 4 and in males and females of group 4 on day 5 of exposure. No clinical signs were observed in the animals of groups 2 and 3. Food consumption was reduced in the males of group 4 during the treatment period with Sec-Butyl aminoethanol . Food consumption in females was not affected. Marginal effects on body weight were recorded in the males of group 4. Body weight development in the treated females was not affected. There were no effects on organ weights. No test item-related findings were recorded during necropsy. Microscopic findings consisted of minor centrilobular hepatocellular hypertrophy in a few males of groups 3 and 4, of minor epithelial degeneration in the nasal cavities at low incidence in all test item-treated groups, of formation of large intramucosal vacuoles in animals of groups 3 and 4, respectively and of focal hypercellularity within the olfactory mucosa of the dorsal turbinates in females of group 4. Based on the histopathological findings in this study the Low-Observed Adverse Effect Concentration (LOAEC) for the nasal irritation was 28 mg/m3. No-Observed Adverse Effect Concentrations (NOAEC) for systemic toxicity were 91 mg/m3 for male rats (based on a decreased body weight gain) and higher than 281 mg/m3 for female rats.

 

 

Oral route

 

The potential toxic effects of the test item, sec-butyl aminoethanol was evaluated following daily oral administration (gavage) to male and female rats from before mating, through mating and gestation and until day 4post-partum (p.p.)(Spezia, 2011a). This study was conducted as a reproduction/developmental screening test according to OECD 421 guideline and GLP. Three groups of 10 male and 10 female Sprague-Dawley rats received the test item, Sec-Butyl aminoethanol(purity 99.7%), by oral (gavage) administration once a day, 2 weeks before mating, through mating and gestation and until day 4p.p..The dose-levels were 10, 50 or 100 mg/kg/day. Another group of 10 males and 10 females received the vehicle, drinking water treated by reverse osmosis, alone, under the same experimental conditions and acted as a control group. The dosing volume was 10 mL/kg/day. Clinical signs and mortality were checked once and twice a day during the treatment period, respectively. Body weight and food consumption were recorded weekly and at determined intervals for females during gestation and lactation. The males were sacrificed after at least 5 weeks of treatment. The body and selected organs were weighed and a complete macroscopicpost-mortemexamination was performed. A microscopic examination was performed on the kidneys, stomach with forestomach, epididymis, testes and thymus from the males in the control- and high‑dose groups, liver from all groups and on all macroscopic lesions. The dams were sacrificed on day 5p.p.,the body and selected organs were weighed and a complete macroscopic examination was performed. A microscopic examination was performed on the kidneys and the stomach with forestomach, in the control and high-dose groups and, on the liver, ovaries (with oviducts) and thymus in all groups and on all macroscopic lesions.

There were no unscheduled deaths in males. There were no treatment-related clinical signs in males and in females during the premating, pregnancy or lactation periods. There were no treatment-related effects on mean body weights or mean body weight changes in males and in females during the premating period. In females at 100 mg/kg/day only and on day 20p.c.,there was a markedly and statistically significant reduction in mean body weight (-21.3% vs. controls, p < 0.001). Mean body weight change was also markedly reduced at 100 mg/kg/day on periods of days 7 to 14 (-33.3% vs. controls, p > 0.05) and days 14 to 20p.c.(‑92.4%vs.controls, p < 0.001), resulting in an overall reduction of -55.6% vs. controls (p < 0.001) on period of days 0 to 20p.c.Taking into account both the amplitude of the effects and their presence in the high-dose group only, these finding were considered to be related to the treatment by the test item. There were no treatment-related effects on mean food consumption in male. At 100 mg/kg/day, in females and during the pregnancy period only, mean food consumption was moderately reduced on days 14 to 20 (-16.1vs.controls, p < 0.05). This effect was considered to be related to the treatment by the test item. Treatment-related lower liver weights were noted in males and females at 100 mg/kg/day and correlated microscopically with lower glycogen content in hepatocytes of treated animals. There was a trend to dose-related decreased glycogen storage in females from 10 mg/kg/day. This change was not considered to be adverse. No treatment-related macroscopic changes were noted in males and females (including the prematurely sacrificed one) given the test item. Qualitative testis staging did not indicate any abnormalities in the integrity of the various cell types present within the different stages of the spermatogenic cycle. Treatment-related microscopic increased size of follicular structures was observed in the ovaries of animals given 100 mg/kg/day. Although marginal, the increased incidence and severity of the ovarian change in females given 50 mg/kg/day was considered to be likely related to the test item.

The test item, Sec-Butyl aminoethanol (99.7% purity), was administered daily by oral gavage to male and female Sprague‑Dawley rats, for 2 weeks before mating, during mating, gestation and until day 5post‑partum, at dose-levels of 10, 50 or 100 mg/kg/day.  

At the dose-levels of 10 and 50 mg/kg/day, there was no treatment-related effect.

At the dose-level of 100 mg/kg/day, no treatment-related effect was observed in male rats. Mean body weight gain of females was markedly reduced during the whole gestation and mean food consumption was reduced on days 14 to 20 of gestation. High absolute and relative mean thymus weights and a higher incidence and severity of increased size of follicular structures in ovaries were noted in females.

Based on the results of this study:

. the No Observed Adverse Effect Level (NOAEL) for parental toxicity was considered to be higher than 100 mg/kg/day in males and 50 mg/kg/day in females (based on the reduced body weight gain during gestation).

The potential toxicity of the test item, sec-butylaminoethanol was evaluated following daily oral administration (gavage) to rats for 2 weeks, in order to select dose-levels for an OECD 421 study (CIT/Study No. 37514 RSR) (Spezia, 2011b). The test item, Sec-Butyl aminoethanol (purity 99.76%), as administered to three groups of three male and three female Sprague-Dawley rats by oral gavage once daily at 100, 300 or 1000 mg/kg/day. The duration of treatment was 2 weeks, except for the 1000 mg/kg/day group: following marked clinical signs and premature death of half of the animals, treatment was stopped after 2 days of dosing. A constant dose volume of 10 mL/kg/day was used. An additional group of three males and three females was administered the vehicle alone, drinking water treated by reverse osmosis, under the same experimental conditions (for 2 weeks). The animals were checked daily for mortality and clinical signs. Body weight and food consumption were recorded twice weekly. On completion of the treatment period day 4 (high-dose group) or day 15 (other groups), after at least 14 hours fasting, all surviving animals were sacrificed. A complete macroscopic post-mortem examination was performed on all animals and designated organs were weighed. No microscopic examination was performed. At 1000 mg/kg/day, one male and two females were found dead on day 3. Clinical signs preceded the deaths included hunched back, piloerection, ptyalism, coldness to the touch, locomotor and/or breathing difficulties. Same clinical signs as those noted in the found dead animals were noted in surviving rats from days 1 or 2. At necropsy on day 4, there were no test item-related effects on organ weights but macroscopic test item treatment-related findings were observed in the forestomach/stomach (red or white discoloured area, thickening and/or white masses). One surviving male and all surviving females had a small spleen and a small thymus, likely resulting from the decreased terminal body weights and the associated stress. At 300 mg/kg/day, there was one found dead male after treatment on day 14. This rat had hypoactivity before treatment and reflux at dosing on the day of death. Hunched posture, ptyalism, piloerection and loud breathing, as well as body weight loss associated with reduced food consumption were noted several days before death. In surviving animals, clinical signs mainly included hunched posture, piloerection, respiratory difficulties and/or ptyalism from day 2. There were mean body weight losses from day 5 in males and from day 11 in females and severe reductions in mean body weight gain on days 1-5 in both sexes. At this dose-level and in one male, the administration of the test item was associated with reduced food consumption over the first week of the treatment period. At necropsy of surviving animals on day 15, there were no test item-related effects on organ weights but macroscopic test item-related findings were also observed in the forestomach/stomach (yellow deposits and discoloration). Based on the results obtained in this study, the dose-level of 1000 mg/kg/day was lethal, 300 mg/kg/day exceeded the Maximum Tolerated Dose and 100 mg/kg/day was a No-Observed Adverse Effect Level (NOAEL).

Justification for selection of repeated dose toxicity via oral route - systemic effects endpoint:
Key study

Justification for selection of repeated dose toxicity inhalation - systemic effects endpoint:
Key study

Justification for selection of repeated dose toxicity inhalation - local effects endpoint:
Key study

Justification for classification or non-classification

No classification for repeated dose toxicity is warranted according to CLP and DSD criteria.