(3R)-3,7-dimethyloct-6-enenitrile

Acute Toxicity: inhalation

Administrative data

Endpoint:

acute toxicity: inhalation

Type of information:

experimental study

Adequacy of study:

key study

Study period:

1983

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: Non-GLP compliant non-guideline study, available as unpublished report, no restrictions, fully adequate for assessment.

Cross-reference

Reason / purpose for cross-reference:

reference to same study

Reference

Endpoint:

acute toxicity: inhalation

Type of information:

read-across from supporting substance (structural analogue or surrogate)

Adequacy of study:

key study

Study period:

1983

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: Non-GLP compliant non-guideline study, available as unpublished report, no restrictions, fully adequate for assessment.

Justification for type of information:

ANALOGUE APPROACH

1. HYPOTHESIS FOR THE ANALOGUE APPROACH
The structures of the target and source substances are identical and differ only with respect to the ratio of enantiomers where the target substance is a single pure L-isomer and the source substance is an equimolar mixture of L and D isomers.

2. SOURCE AND TARGET CHEMICAL(S) (INCLUDING INFORMATION ON PURITY AND IMPURITIES)
The target substance, L-Citronellyl nitrile, is a mono-constituent substance (EC No. 695-909-8, CAS no. 35931-93-2).
The source substance, DL-Citronellyl nitrile, is a mono-constituent substance (EC No. 257-288-8, CAS no. 51566-62-2).
The source and target substances are both of high purity with a low concentration of impurities.

3. ANALOGUE APPROACH JUSTIFICATION
The read across hypothesis is based on structural similarity where the only difference between target and source molecules is the enantiomeric ratio. In a non-chiral environment the target and source chemicals will have identical properties but in the chiral environment of living organisms the enantiomers may possess different carcinogenicity and teratogenicity (in a chiral environment, stereoisomers might experience selective absorption, protein binding, transport, enzyme interactions and metabolism, receptor interactions, and DNA binding). Therefore, as a precaution for the developmental toxicity endpoint it is suggested that the NOAEL 250 mg/kg bw/day for L-Citronellyl nitrile is used instead of 500 mg/kg bw/day, as it is not known which form is more potent in vivo. All other endpoints are considered to be acceptable for this substance assuming that 50% of the target compound is available in the test material.

4. DATA MATRIX
Please refer to the data matrix included in the read-across justification document attached in Section 13.2.

Reason / purpose for cross-reference:

read-across source

Qualifier:

equivalent or similar to guideline

Guideline:

OECD Guideline 403 (Acute Inhalation Toxicity)

Principles of method if other than guideline:

BASF-Test: The study was conducted according to an internal BASF method which in principle is comparable to the OECD Guideline 403.
A test group consisting of 10 animals/sex was treated by single inhalation application; aerosol of the test substance. The animals were observed for mortality and for clinical symptoms of toxicity. At the end of the observation period of 14 days, the surviving animals were sacrificed for the purpose of necropsy.

GLP compliance:

no

Test type:

standard acute method

Limit test:

yes

Species:

rat

Strain:

Wistar

Sex:

male/female

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Source: Dr. K. Thomae GmbH, D-7950 Biberach, FRG
- Age at study initiation: 8 weeks
- Weight at study initiation: male animals 256 ± 22 g, female animals 176 ± 13 g.
- Housing: They were housed in groups of five in wire cages of Becker, type D III, without bedding
- Diet: The animais were offered maintenance diet for rats, mice and hamsters, SSNIFF R 10 mm pellet, SSNIFF-Versuchstierdiaten GmbH, D-4770 Soest, FRG.
- Water: Tap water ad libitum during the post-exposure observation period.

ENVIRONMENTAL CONDITIONS
- Temperature (°C): 20 - 24
- Humidity (%): 30-70
- Photoperiod (hrs dark / hrs light): 12/12

Route of administration:

inhalation: aerosol

Type of inhalation exposure:

nose/head only

Vehicle:

air

Details on inhalation exposure:

TECHNICAL PROCEDURE:
- Exposure system: Head-nose inhalation system INA 20 (glass-steel construction, BASF Aktiengesellschaft, V ≈ 55 L); the animals are restrained in tubes and their snouts project into the inhalation chamber.
- Generator system: By means of a continuous infusion pump, INFU 362 (INDIGEL/Switzerland) and a two-component atomizer, mod. 970 (Schlick), a mixture of aerosol and air was generated.
- Experimental procedure: Constant amounts of the substance to be tested were supplied to a two-component atomizer by means of a metering pump. By means of compressed air (1.45 bar) an aerosol was generated, which was passed into the inhalation system. The exhaust air system was adjusted by 10% lower against the supply air system (positive pressure). This ensured that the mixture of test substance and air was not diluted by laboratory air in the breathing zones of the animals.

ANALYTICAL INVESTIGATIONS:
- Sampling: Apparatus: Quartz wool and a downstream fritted glass flask, BASF sampling station (with gas meter, impulse counter and automatic pump switching); Sorption solvent: 2-propanol; Sampling velocity: 1.25 m/s; Sampling amount: 1 L; Sampling site: immediately adjacent to the animal noses; Sampling probe ø: 7 mm; Sampling frequency: 1 sample every hour.
- Analytical method of determination: A gas-chromatographic method was used for the quantitative assay of the aerosol concentration. The aerosol samples were taken up in 40 mL 2-propanol (solvent). Gas-chromatographic method: GC HP/5840 A (Hewlett Packard). An internal standard was pipetted to the absorption sample contained in a 50 mL measuring flask and made up to the calibration mark. The chromatograpbic peak area was compared with calibration values and calculated.
- Particle size analysis: Equipment: Andersen Stack Sampler Mark III, Millipore vacuum compressed air pump XX 60 220 50, limiting orifice 3 L/min Millipore, sampling probe, internal diameter 6.9 mm, stopwatch. Procedure: 30 minutes after the beginning of the test at the earliest, one sample of the test group was taken for the particle size analysis. Before the sampling, the impactor was equipped with metal collecting discs and a backup particle filter. The impactor was connected to the pump and the test apparatus, and a sample (12 L) was removed. The impactor was taken apart, the collecting discs and the pre-impactor were rinsed with the solvent, the backup particle filter was eluted, and the samples obtained were analyzed by gas chromatography.

Analytical verification of test atmosphere concentrations:

yes

Duration of exposure:

4 h

Concentrations:

4.9 mg/L

No. of animals per sex per dose:

10

Control animals:

no

Details on study design:

Observation period: After the exposure period the surviving animals were observed for 14 days.
Clinical examinations: The body weight of the animals was checked before the beginning of the test, after 7 days and at the end of the observation period and was presented graphically. Clinical symptoms were recorded each workday. Mortality was checked each day.
Pathology: At the end of the 14-day observation period, the animals were sacrificed by CO2 and were subjected to a grosspathological examination.

Statistics:

The statistical evaluation of the concentration-response relationship was carried out in accordance with the binomial test (Wittig, H.: Mathematische Statistik 1974, pp. 32 - 35) according to tables of the BASF Computer Center.

Sex:

male/female

Dose descriptor:

LC50

Effect level:

> 4.9 mg/L air

Based on:

test mat.

Exp. duration:

4 h

Mortality:

No mortality was observed.

Clinical signs:

other: During exposure: aqueous discharge from noses, salivation. After exposure: aqueous, slight discharge from noses, salivation, reddened ears and limbs. After one day the animals were without findings.

Body weight:

The body weights of the test group were unimpaired on comparison to a control collective.

Gross pathology:

Organs: no abnormalities detected.

Other findings:

The MMAD 50% = 3.0 µm (geometrical standard deviation 2.9) was calculated from the results of the particle size analysis.
A fraction of 89% of the aerosol passing through the alveoli was obtained from the results of the particle size analysis.

Interpretation of results:

GHS criteria not met

Conclusions:

LC50: >4.9 mg/L on male / females.

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

1983

Report date:

1983

Materials and methods

Test guideline

Qualifier:

equivalent or similar to guideline

Guideline:

OECD Guideline 403 (Acute Inhalation Toxicity)

Principles of method if other than guideline:

BASF-Test: The study was conducted according to an internal BASF method which in principle is comparable to the OECD Guideline 403.
A test group consisting of 10 animals/sex was treated by single inhalation application; aerosol of the test substance. The animals were observed for mortality and for clinical symptoms of toxicity. At the end of the observation period of 14 days, the surviving animals were sacrificed for the purpose of necropsy.

GLP compliance:

no

Test type:

standard acute method

Limit test:

yes

Test material

Test material information

Constituent 1

Reference substance name:

3,7-dimethyloct-6-enenitrile

EC Number:

257-288-8

EC Name:

3,7-dimethyloct-6-enenitrile

Cas Number:

51566-62-2

Molecular formula:

C10H17N

IUPAC Name:

3,7-dimethyloct-6-enenitrile

Details on test material:

- Name of test material: Citronellylnitril
- Stability: At least 2 years under exclusion of oxygen

Test animals

Species:

rat

Strain:

Wistar

Sex:

male/female

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Source: Dr. K. Thomae GmbH, D-7950 Biberach, FRG
- Age at study initiation: 8 weeks
- Weight at study initiation: male animals 256 ± 22 g, female animals 176 ± 13 g.
- Housing: They were housed in groups of five in wire cages of Becker, type D III, without bedding
- Diet: The animais were offered maintenance diet for rats, mice and hamsters, SSNIFF R 10 mm pellet, SSNIFF-Versuchstierdiaten GmbH, D-4770 Soest, FRG.
- Water: Tap water ad libitum during the post-exposure observation period.

ENVIRONMENTAL CONDITIONS
- Temperature (°C): 20 - 24
- Humidity (%): 30-70
- Photoperiod (hrs dark / hrs light): 12/12

Administration / exposure

Route of administration:

inhalation: aerosol

Type of inhalation exposure:

nose/head only

Vehicle:

air

Details on inhalation exposure:

TECHNICAL PROCEDURE:
- Exposure system: Head-nose inhalation system INA 20 (glass-steel construction, BASF Aktiengesellschaft, V ≈ 55 L); the animals are restrained in tubes and their snouts project into the inhalation chamber.
- Generator system: By means of a continuous infusion pump, INFU 362 (INDIGEL/Switzerland) and a two-component atomizer, mod. 970 (Schlick), a mixture of aerosol and air was generated.
- Experimental procedure: Constant amounts of the substance to be tested were supplied to a two-component atomizer by means of a metering pump. By means of compressed air (1.45 bar) an aerosol was generated, which was passed into the inhalation system. The exhaust air system was adjusted by 10% lower against the supply air system (positive pressure). This ensured that the mixture of test substance and air was not diluted by laboratory air in the breathing zones of the animals.

ANALYTICAL INVESTIGATIONS:
- Sampling: Apparatus: Quartz wool and a downstream fritted glass flask, BASF sampling station (with gas meter, impulse counter and automatic pump switching); Sorption solvent: 2-propanol; Sampling velocity: 1.25 m/s; Sampling amount: 1 L; Sampling site: immediately adjacent to the animal noses; Sampling probe ø: 7 mm; Sampling frequency: 1 sample every hour.
- Analytical method of determination: A gas-chromatographic method was used for the quantitative assay of the aerosol concentration. The aerosol samples were taken up in 40 mL 2-propanol (solvent). Gas-chromatographic method: GC HP/5840 A (Hewlett Packard). An internal standard was pipetted to the absorption sample contained in a 50 mL measuring flask and made up to the calibration mark. The chromatograpbic peak area was compared with calibration values and calculated.
- Particle size analysis: Equipment: Andersen Stack Sampler Mark III, Millipore vacuum compressed air pump XX 60 220 50, limiting orifice 3 L/min Millipore, sampling probe, internal diameter 6.9 mm, stopwatch. Procedure: 30 minutes after the beginning of the test at the earliest, one sample of the test group was taken for the particle size analysis. Before the sampling, the impactor was equipped with metal collecting discs and a backup particle filter. The impactor was connected to the pump and the test apparatus, and a sample (12 L) was removed. The impactor was taken apart, the collecting discs and the pre-impactor were rinsed with the solvent, the backup particle filter was eluted, and the samples obtained were analyzed by gas chromatography.

Analytical verification of test atmosphere concentrations:

yes

Duration of exposure:

4 h

Concentrations:

4.9 mg/L

No. of animals per sex per dose:

10

Control animals:

no

Details on study design:

Observation period: After the exposure period the surviving animals were observed for 14 days.
Clinical examinations: The body weight of the animals was checked before the beginning of the test, after 7 days and at the end of the observation period and was presented graphically. Clinical symptoms were recorded each workday. Mortality was checked each day.
Pathology: At the end of the 14-day observation period, the animals were sacrificed by CO2 and were subjected to a grosspathological examination.

Statistics:

The statistical evaluation of the concentration-response relationship was carried out in accordance with the binomial test (Wittig, H.: Mathematische Statistik 1974, pp. 32 - 35) according to tables of the BASF Computer Center.

Results and discussion

Effect levels

Sex:

male/female

Dose descriptor:

LC50

Effect level:

> 4.9 mg/L air

Based on:

test mat.

Exp. duration:

4 h

Mortality:

No mortality was observed.

Clinical signs:

other: During exposure: aqueous discharge from noses, salivation. After exposure: aqueous, slight discharge from noses, salivation, reddened ears and limbs. After one day the animals were without findings.

Body weight:

The body weights of the test group were unimpaired on comparison to a control collective.

Gross pathology:

Organs: no abnormalities detected.

Other findings:

The MMAD 50% = 3.0 µm (geometrical standard deviation 2.9) was calculated from the results of the particle size analysis.
A fraction of 89% of the aerosol passing through the alveoli was obtained from the results of the particle size analysis.

Applicant's summary and conclusion

Conclusions:

LC50: >4.9 mg/L on male / females.