dec-1-en-4-yne

Acute Toxicity: inhalation

Administrative data

Endpoint:

acute toxicity: inhalation

Type of information:

experimental study

Adequacy of study:

key study

Study period:

02-03-2018 to 05-04-2018

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: Guideline study performed under GLP. All relevant validity criteria were met with acceptable minor deviations not considered to impact the validity of the study.

Justification for type of information:

Information as to the availability of the in vivo study is provided in 'attached justification'.

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2018

Report date:

2018

Materials and methods

Test guideline

Test guideline 1

Qualifier:

according to guideline

Guideline:

OECD Guideline 403 (Acute Inhalation Toxicity)

Deviations:

yes

Remarks:

The relative humidity within the exposure chamber during the test exposure was found to be lower than the range specified in the inhalation test guidelines (30-70 %) ; not considered to impact the study

Test guideline 2

Qualifier:

according to guideline

Guideline:

EU Method B.2 (Acute Toxicity (Inhalation))

Deviations:

yes

Remarks:

See above

GLP compliance:

yes (incl. QA statement)

Remarks:

inspected: July 2017 ; signature: November 2017

Test type:

traditional method

Limit test:

no

Test material

Test material information

Constituent 1

Reference substance name:

dec-1-en-4-yne

EC Number:

813-331-8

Cas Number:

24948-66-1

Molecular formula:

C10H16

IUPAC Name:

dec-1-en-4-yne

Test material form:

liquid

Details on test material:

- Physical state: Liquid
- Storage condition of test material: Approximately 4 °C, in the dark under nitrogen
- Other: Slightly yellow

Test animals

Species:

rat

Strain:

Wistar

Remarks:

RccHan: WIST

Sex:

male/female

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Rationale for alternative/additional species to rat: Not applicable.
- Source: Recognised supplier (documented in the full study report)
- Females (if applicable) nulliparous and non-pregnant: Yes.
- Rationale for use of males: Not applicable.
- Age at study initiation: 8 - 12 weeks.
- Weight at study initiation: sighting exposure: 304 g male / 245 g female (4.83 mg/L mean achieved concn.); definitive test: 246 - 279 g male / 222 - 237 g female (4.90 mg/L mean achieved concn.) ; bodyweight variation did not exceed ±20% of the mean bodyweight at study initiation.
- Fasting period before study: None.
- Housing: Housed in groups of up to five by sex in solid-floor polypropylene cages with stainless steel lids, furnished with softwood flakes provided with environmental enrichment items.
- Historical data: The laboratory has a historic control dataset (not documented in the full study report).
- Diet (e.g. ad libitum): Certified diet from recognised supplier, provided ad libitum (except for exposure period period)
- Water (e.g. ad libitum): ad libitum (except for exposure period period)
- Acclimation period: At least 5 days.
- Microbiological status when known: No issues reported within the study.
- Method of randomisation in assigning animals to test and control groups: Randomly allocated to cages after receipt.

ENVIRONMENTAL CONDITIONS
- Temperature (°C): 19 - 25
- Humidity (%): 20-23 ; the relative humidity within the exposure chamber during the test exposure was found to be lower than the range specified in the inhalation test guidelines (30-70 %) ; not considered to impact the study
- Air changes (per hr): > 15 air changes per hour
- Photoperiod: 12 h light / 12 h dark

IN-LIFE DATES: From: To: 2018-03-29 to 2018-04-05

Administration / exposure

Route of administration:

inhalation: aerosol

Type of inhalation exposure:

nose only

Vehicle:

air

Remarks:

Oxygen concentration (%) was monitored during the study by an electronic oxygen analyzer. The test atmospheres were generated to contain at least 19% oxygen.

Mass median aerodynamic diameter (MMAD):

3.6 µm

Geometric standard deviation (GSD):

3.48

Remark on MMAD/GSD:

MMAD and GSD associated with the highest concentration level: 4.90 mg/L mean achieved concentration (5.0 mg/L target ; 12.25 mg/L nominal)

Details on inhalation exposure:

TEST ATMOSPHERE
- Brief description of analytical method used: The test atmosphere was sampled nine times during each exposure period. A weighed glass fiber filter was placed in a filter holder and temporarily sealed in a vacant port of the exposure chamber in the animals’ breathing zone. A known quantity of the exposure chamber atmosphere was drawn through the filter using a vacuum pump. The samples were then submitted for chemical analysis by gas chromatography (GC). The sampling procedure involved two liters or five liters of test atmosphere being drawn through a series of two glass impingers (dependent on concentration) containing Methanol (each made up to 80mL). The samples were then submitted for chemical analysis by gas chromatography (GC). The test impinger samples received were diluted with acetonitrile to achieve the working concentration. The solvent (acetonitrile) and a blank impinger (control) were analysed. Neither the solvent nor the blank impinger produced a signal that interfered with the signal due to the test item. A range of standard solutions were prepared in dilution solvent from a stock solution of 1.012 mg/mL by serial dilution covering the concentration range 0.0506 to 0.1518 mg/mL. Full details of the analytical method are provided in the full study report. The linearity of the analytical system used for sample analyses was demonstrated with a good relationship between peak areas measured and working standard concentrations. The regression coefficients calculated were found to be > 0.9999. The fortified samples of impingers were found to have a recovery value of ± 10% of the fortification chromatographic run. In conclusion, the results indicate the accurate use of the test item and impingers during this study. Working solutions of the test item were shown to be sufficiently stable to complete the analysis without deterioration of the analyte. Full details of the analytical method are provided in the full study report.
- Samples taken from breathing zone: yes

TEST ATMOSPHERE
- Particle size distribution: The particle size of the generated atmosphere inside the exposure chamber was determined three times during each exposure period using a cascade impactor. The particle size distribution for each group is reported in table 1.
- MMAD (Mass median aerodynamic diameter) / GSD (Geometric st. dev.): The Mass Median Aerodynamic Diameter (MMAD) was determined and is reported for each group in table 1.

Analytical verification of test atmosphere concentrations:

yes

Duration of exposure:

4 h

Remarks on duration:

In accordance with the OECD TG 403 guidelines.

Concentrations:

Following an appropriate equilibration period each group(s) were subjected to a single exposure to the test item for a period of four hours. Based on the expected toxicity of the test item, target concentrations would be set and used for exposure. Further concentrations were selected after consideration of the results of the previous exposure. Full details are provided in table 2.

No. of animals per sex per dose:

5 per sex per dose

Control animals:

no

Details on study design:

- Duration of observation period following administration: 14 days
- Frequency of observations and weighing: Clinical signs at hourly intervals during exposure, immediately on removal from the restraining tubes at the end of exposure, one hour after termination of exposure and subsequently once daily for up to fourteen days. Any evidence of mortality or overt toxicity was recorded at each observation. Individual body weights were recorded on arrival, prior to treatment on the day of exposure and on Days 1, 3, 7 and 14 or after mortality.
- Necropsy of survivors performed: yes (and in the event of any mortalities)
- Other examinations performed: clinical signs, bodyweight, organ weights, and any other relevant toxicological effects were reported.

Statistics:

Using the mortality data obtained, typically an estimate of the acute inhalation median lethal concentration (LC50) would be calculated using validated data analysis software which utilized Log-Normal (Probit) regression models in order to calculate the LC50 values. LC50 values and 95% confidence limits would be calculated for males and females separately. Where appropriate.

Results and discussion

Effect levels

Effect levels 1

Key result

Sex:

male/female

Dose descriptor:

LC50

Effect level:

> 4.9 mg/L air

Based on:

test mat.

Exp. duration:

4 h

Remarks on result:

other: Effect levels based on analytically confirmed: mean achieved concentrations for each exposure/sex groups

Effect levels 2

Sex:

male

Dose descriptor:

LC50

Effect level:

> 4.9 mg/L air

Based on:

test mat.

Exp. duration:

4 h

Remarks on result:

other: Effect levels based on analytically confirmed: mean achieved concentrations for each exposure/sex groups

Effect levels 3

Sex:

female

Dose descriptor:

LC50

Effect level:

> 4.9 mg/L air

Based on:

test mat.

Exp. duration:

4 h

Remarks on result:

other: Effect levels based on analytically confirmed: mean achieved concentrations for each exposure/sex groups

Mortality:

There were no mortalities during the study as reported in table 3.

Clinical signs:

lethargy (hypoactivity)

Remarks:

See "any other information on results incl. tables" for further information

Body weight:

Sighting exposure: 4.83 mg/L mean achieved concn. : All males and females exhibited body weight losses on Day 1 post-exposure. Body weight gains were noted in all males/females during the remainder of the recovery period.
In group 1, definitive test : 4.83 mg/L mean achieved concn : All males/females exhibited body weight losses or no gain in body weight on the first day postexposure.With the exception of two males and four females which exhibited body weight losses from Days 1 to 3 post-exposure, body weight gains were noted for all animals during the remainder of the recovery period. All males/females were gaining bodyweight at the end of the recovery period.

Gross pathology:

In group 2, 6.43 mg/L: Abnormally red lungs or dark patches on the lungs were noted in two males (out of five) and two females (out of five) at necropsy.
In group 1, 2.14 mg/L: Dark patches on the lungs were noted in two males (out of five) and one female (out of five) at necropsy.

Other findings:

- Other observations: The respiratory tract was subjected to a detailed macroscopic examination for signs of irritancy or local toxicity during necropsy.

Any other information on results incl. tables

Table 1.0 : Characteristics of the achieved atmosphere (sighting test and definitive test : group 1 of 1)

Group Number	Nominal Concentration (mg/L)	Mean achieved actual concentration (mg/L)	Mean Mass Median Aerodynamic Diameter (µm)	Inhalable Fraction (% <4 µm)	Geometric Standard Deviation	Comments
Sighting test (target concn. 3.5 mg/L)	8.98	4.83 ± 0.2	2.75	65.8	2.52	n=9 samples
1 (target concn. 5.0 mg/L)	12.25	4.90 ± 0.2	3.60	53.4	3.48	n= 9 samples ; generation efficiency (ratio of actual and nominal concentration) of 250%

 

Table 2.0 : Mortality data (sighting test and definitive test : group 1 of 1)

Group Number	Nominal Concentration (mg/L)	Mean achieved actual concentration (mg/L)	Mortalities
			Female	Male
Sighting test (target concn. 3.5 mg/L)	8.98	4.83 ± 0.2	0/1	0/1
1 (target concn. 5.0 mg/L)	12.25	4.90 ± 0.2	0/5	0/5

Common clinical sign abnormalities noted during the study (not associated with the restraining procedure) included decreased respiratory rate, frequent instances of body tremors. On removal from the chamber all animals exhibited body tremors, there were frequent instances of lethargy and ataxia and an isolated instance of prostration.One day after exposure, all animals exhibited hunched posture. On Day 2 post-exposure, there were occasional instances of areas of red/brown staining of the fur and an isolated instance of areas of red brown staining around the eyes. Animals recovered so that no significant abnormalities were apparent from Days 2 to 4 post-exposure.

Applicant's summary and conclusion

Interpretation of results:

GHS criteria not met

Remarks:

Criteria used for interpretation of results: EU

Conclusions:

Under the conditions of this study, the inhalation LC50 (male/female) was: > 4.90 mg/L mean achieved concentration within the RCCHan WIST rat.

Executive summary:

The study was performed according to OECD TG 403 and EU Method B.2 in accordance with GLP to assess the acute inhalation toxicity of the test item. As insufficient data was available on the expected inhalation toxicity of the test item, a sighting test was performed to determine the initial exposure concentration. A group of one male and one female was exposed to an aerosol atmosphere of the test item at a target concentration of 3.5 mg/L (mean achieved concentration: 4.83 m/L). Based on the results of the sighting test, a limit test was performed. A group of ten animals (five males and five females) was exposed to an aerosol atmosphere of the test item at a target concentration of 5.0 mg/L for 4 hours using a nose only exposure system, followed by a fourteen day observation period. The mean achieved atmosphere concentrations was 4.90 mg/L The characteristics of the achieved atmosphere where Mean Mass Median Diameter (particle size) and Inhalable Fraction <4 μm: sighting test: 2.75 μm and 65.8% and Group 1 (4.90 mg/L limit test): 3.60 μm and 53.4%. The Geometric Standard Deviation was sighting test : 2.52 and Group 1 (4.90 mg/L limit test): 3.48, respectively. There were no male or female mortalities. In the definitive limit test - Group 1: Common abnormalities noted during the study included decreased respiratory rate, hunched posture, pilo-erection, body tremors and wet fur. There were frequent instances of ataxia and lethargy, occasional instances of areas of red/brown staining of the fur and fur stained yellow by test item and isolated instances of vocalization, prostration and areas of red/brown staining around the eyes. Animals recovered so that no significant abnormalities were apparent from Days 2 to 4 post-exposure. All animals exhibited body weight losses or no gain in body weight on the first day post-exposure. With the exception of two males and four females which exhibited body weight losses from Days 1 to 3 post-exposure, body weight gains were noted for all animals during the remainder of the recovery period. All males/females were gaining bodyweight at the end of the recovery period. During necropsy in Group 1,: the following macroscopic abnormalities were detected :Lungs – Pale, abnormally red, dark patches ; Liver – Pale, patchy pallor (1 female) ; Kidneys – Pale (1 male) ; Large intestine – Gaseous distension (2 animals ; 1 male, 1 female). Under the conditions of this study, the inhalation LC50 (male/female) was > 4.90 mg/L within the RCCHan WIST rat.