7-hydroxycitronellal

Repeated dose toxicity: inhalation

Administrative data

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:

guideline study

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2013

Report date:

2013

Materials and methods

Test guideline

Qualifier:

according to guideline

Guideline:

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

Deviations:

yes

Remarks:

Exposure period 2 weeks

GLP compliance:

yes

Limit test:

no

Test material

Test material information

Constituent 1

Reference substance name:

7-hydroxycitronellal

EC Number:

203-518-7

EC Name:

7-hydroxycitronellal

Cas Number:

107-75-5

Molecular formula:

C10H20O2

IUPAC Name:

7-hydroxy-3,7-dimethyloctanal

Test material form:

not specified

Details on test material:

- Name of test material (as cited in study report): Hydroxycitronellal
- Lot No. 00046177L0
- Physical state: Clear, colorless liquid
- Analytical purity: 99.8%
- Stability under test conditions: confirmed by analysis during study
- Storage condition of test material: room temperature, protected from light

Test animals

Species:

rat

Strain:

other: Crl:CD(SD)

Sex:

male/female

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Age at study initiation: approximately 7 weeks old
- Weight at study initiation: male (196 to 233 g), female (154 to 189 g)
- Housing: individually in clean, stainless steel, wire-mesh cages
- Diet: Rodent LabDiet 5002
- Water: reverse osmosis-treated drinking water
- Diet and water restrictions:
during acclimation to the nose-only restraint and the exposure period: no food and water;
prior to the scheduled necropsy, food was offered for at least 2 hours after each animal's final exposure prior to removal for the overnight fasting period, during the period of fasting prior to necropsy: no food, water ad libitum;
- Acclimation period: minimum 13 days; 5 days prior to the initiation of exposure, all animals were acclimated to nose-only exposure tubes; restraint acclimation was performed for approximately 1 hour for the first day, 2 hours for the second day, 3 hours for the third day, 4 hours for the fourth day and 6 hours for the fifth day

ENVIRONMENTAL CONDITIONS
- Temperature (°C): 22 +/- 3
- Humidity (%): 50 +/- 20
- Air changes (per hr): 10
- Photoperiod (hrs dark / hrs light): 12/12

Administration / exposure

Route of administration:

inhalation: aerosol

Type of inhalation exposure:

nose only

Vehicle:

air

Remarks on MMAD:

MMAD / GSD: Aerosol particle size determinations were conducted for each test substance exposure system using a 7-stage brass cascade impactor. Pre-weighed, glass-fiber filters were used as the collection substrates.
The mean MMAD and GSD ranged between 2.2-2.4 and 2.36-2.54, respectively

Details on inhalation exposure:

An aerosol atmosphere was generated using a 6-jet Collison nebulizer.

Analytical verification of doses or concentrations:

yes

Details on analytical verification of doses or concentrations:

Exposure concentrations of the test material (combined vapor and aerosol) within each nose-only system were determined using an appropriate gas chromatography (GC) method. Concentrations were determined at approximately 60 minute intervals for each test material exposure system and at least once daily for the control system.

Duration of treatment / exposure:

2 weeks

Frequency of treatment:

6 hours per day, 5 days per week

Doses / concentrations

Doses / concentrations 1

Remarks:

Doses / Concentrations:
0.70, 7.0 and 70 mg/m3 (equivalent to 0.1, 1 and 10 ppm)
Basis:
nominal conc.

Doses / concentrations 2

Remarks:

Doses / Concentrations:
0.84, 6.4 and 73 mg/m3
Basis:
analytical conc.

No. of animals per sex per dose:

10

Control animals:

other: exposed to filtered air

Positive control:

Not applicable

Examinations

Observations and examinations performed and frequency:

MORTALITY AND MORBIDITY: Yes
- Time schedule: twice daily

CLINICAL OBSERVATIONS: Yes
- Time schedule: prior to exposure, at the approximate midpoint of each exposure for visible signs of animals in nose-only exposure restraint tubes and at 0-1 hour following exposure on exposure days and once daily on non-exposure days. Detailed physical examinations were performed during the pretest period, at randomization, weekly during the exposure period and prior to the scheduled necropsy for each animal.

BODY WEIGHT: Yes
- Time schedule for examinations: during the pretest period, at randomization, prior to the first exposure and twice weekly for the duration of the study, including the day before the scheduled necropsy

FOOD CONSUMPTION: Yes
- Food consumption for each animal determined: Yes
- Time schedule: during the pretest period and twice weekly during the exposure period

HAEMATOLOGY - COAGULATION PARAMETERS: Yes
- Time schedule for collection of blood: day of necropsy (study day 12/13)
- Animals fasted: Yes (overnight fasting period)
- How many animals: all
Total leukocyte count, Erythrocyte count, Hemoglobin, Hematocrit, Mean corpuscular volume, Mean corpuscular hemoglobin, Mean corpuscular hemoglobin concentration, Platelet count, Prothrombin time, Activated partial thromboplastin time, Reticulocyte count, Mean Platelet Volume, Differential leukocyte count, Red cell distribution width , Hemoglobin Distribution Width, Platelet estimate, Red cell morphology


CLINICAL CHEMISTRY: Yes
- Time schedule for collection of blood: day of necropsy (study day 12/13)
- Animals fasted: Yes (overnight fasting period)
- How many animals: all
Albumin, Total protein, Globulin, Albumin/globulin ratio, Total bilirubin, Urea nitrogen, Creatinine, Alkaline phosphatase, Alanine aminotransferase, Aspartate aminotransferase, Gamma glutamyltransferase, Glucose, Total cholesterol, Calcium, Chloride, Phosphorus, Potassium, Sodium, Triglycerides, Sorbitol dehydrogenase, Lactate dehydrogenase, Hemolysis, Lipemia, Icterus


SERUM CYTOKINE EVALUATION:
- Time schedule: at necropsy
- How many animals: 5 animals/sex/group (BALF animals)
- samples were taken, but not further assessed for cytokines

BRONCHOALVEOLAR LAVAGE (BAL): Yes
- Time schedule: at necropsy
- How many animals: 5 animals/sex/group (BALF animals)
- Examined parameters: lactate dehydrogenase, total protein, alkaline phosphatase, Total and differential cell counts (Alveolar macrophages, Neutrophils, Lymphocytes, Eosinophils, Basophils), cytokines (TNF-α, IL-5, IL-10, ICAM-1, IFN-γ, IL-4, TGF-β, MCP-1, IL-1β, IL-13, MIP-2, RANTES)

Sacrifice and pathology:

On the day following the final exposure, all animals were sacrificed and subjected to necropsy. Animals were subjected to either tissue
collection (5 animals/sex/group; histopathology animals) or bronchoalveolar lavage (5 animals/sex/group; BALF animals).

GROSS PATHOLOGY and HISTOPATHOLOGY: Yes
- selected organs were weighed and selected tissues were examined microscopically from 5 animals/sex/group (histopathology animals) at the scheduled necropsy
Organ weights:
Adrenals, Brain, Heart, Kidneys, Liver, Lungs (prior to inflation with fixative), Ovaries with oviducts, Spleen, Testes, Thymus, Thyroid with parathyroids.

Histopathology:
Microscopic examination of the lungs (with bronchi), BALT, nasal tissues, NALT, larynx, trachea, mediastinal and bronchial lymph nodes, and gross lesions were performed for 5 animals/sex/group (Subgroup 1) not assigned for the BAL at the scheduled necropsy. In addition, microscopic examination was performed on the kidneys and liver from 5 animals/sex/group (Subgroup 1) in the control and 70 mg/m3 (high exposure level) groups at the scheduled necropsy. For the nasal cavity and turbinates, 6 sections were examined, including a section containing the nasopharyngeal duct. Three levels of the larynx, including 1 at the base of the epiglottis, were examined. At least 2 sections of the trachea were examined, including 1 longitudinal section through the carina of the extrapulmonary bifurcation of bronchi and 1 transverse section taken at approximately the midpoint of the trachea.

Statistics:

Analyses were conducted using two-tailed tests (except as noted otherwise) for minimum significance levels of 1% and 5%, comparing each test substance-treated group to the control group by sex.
Body weight, body weight change, food consumption, clinical pathology, BALF parameters, and organ weight data were subjected to a parametric one-way ANOVA to determine intergroup differences. If the ANOVA revealed statistically significant (p<0.05) intergroup variance, Dunnett's test
was used to compare the test substance-treated groups to the control group.

Results and discussion

Results of examinations

Details on results:

CLINICAL SIGNS AND MORTALITY
All animals survived to scheduled necropsy in all dose goups. Yellow material was found on various body surfaces in the females at dose level of 70 mg/m3. This finding was not considered to be adverse. No other test material related clinical observations at this dose level or dose level of 0.70 mg/m3 and 7.0 mg/m3 were observed.

BODY WEIGHT AND WEIGHT GAIN
Body weights were unaffected by test substance exposure. There were no statistically
significant differences when the control and test substance-exposed groups were
compared.

FOOD CONSUMPTION
Food consumption was unaffected by test substance exposure. There were no statistically
significant differences when the control and test substance-exposed groups were
compared.

HAEMATOLOGY
There were no alterations in hematology parameters that were associated with test substance exposure.

CLINICAL CHEMISTRY
There were no alterations in serum chemistry parameters that were associated with test
substance exposure.

ORGAN WEIGHTS
Organ weights were unaffected by test substance exposure.

GROSS PATHOLOGY
There were no test substance-related macroscopic findings at the scheduled necropsy.

HISTOPATHOLOGY: NON-NEOPLASTIC
There were no test substance-related microscopic findings.

BRONCHOALVEOLAR LAVAGE CLINICAL CHEMISTRY
There were no alterations in BALF chemistry parameters that were associated with test
substance exposure.

BRONCHOALVEOLAR LAVAGE CYTOLOGY
There were no alterations in BALF cytology that were associated with test substance
exposure.

BRONCHOALVEOLAR LAVAGE FLUID CYTOKINE ANALYSIS
There were no alterations in BALF cytokine levels that were associated with test
substance exposure.

Effect levels

Dose descriptor:

NOAEC

Effect level:

70 mg/m³ air

Based on:

test mat.

Sex:

male/female

Basis for effect level:

other: nonadverse clinical observations in the 70 mg/m3 group females

Target system / organ toxicity

Critical effects observed:

not specified