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Toxicological information

Repeated dose toxicity: inhalation

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Administrative data

Endpoint:
short-term repeated dose toxicity: inhalation
Remarks:
combined repeated dose and reproduction / developmental screening
Type of information:
migrated information: read-across based on grouping of substances (category approach)
Adequacy of study:
key study
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
other: GLP compliant (except for minor exception listed below), guideline study, available as unpublished report, no restrictions, fully adequate for assessment.

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
2010
Report Date:
2010

Materials and methods

Test guidelineopen allclose all
Qualifier:
according to
Guideline:
OECD Guideline 422 (Combined Repeated Dose Toxicity Study with the Reproduction / Developmental Toxicity Screening Test)
Deviations:
yes
Remarks:
no lot number available of test material
Qualifier:
according to
Guideline:
other: EPA OPPTS 870.3650
GLP compliance:
yes
Limit test:
no

Test material

Reference
Name:
Unnamed
Type:
Constituent
Details on test material:
- Name of test material (as cited in study report): ethane
- Supplier: MG Industries, 3 Great Valley Parkway, Malvern, Pennsylvania 19355, USA
- Substance type: Industrial gas
- Physical state: colourless gas
- Analytical purity: 99.0% per supplier
- Lot/batch No.: Not available
- Stability under test conditions: 99.86% before study, 99.88% after study
- Storage condition of test material: Ambient

Test animals

Species:
rat
Strain:
Sprague-Dawley
Sex:
male/female
Details on test animals and environmental conditions:
TEST ANIMALS
- Species: Albino rats (Outbred) VAF/Plus®, Sprague-Dawley derived (CD®), Crl:CD®(SD)IGS BR
- Source: Charles River Laboratories, Raleigh, North Carolina 27610, USA
- Age at study initiation: Approximately 8 weeks
- Weight at study initiation: Males mean 256 g (range 230-284 G); females mean 197 g (range 167-217 g)
- Fasting period before study: None
- Housing: Individually in stainless steel suspended cages with wire mesh floors and fronts (except for mating period when 1 male and 1 female were housed together)
- Diet: Certified Rodent diet No 5002 (PMI Nutrition International, St Louis, Missouri, USA) ad libitum
- Water: Municipal water ad libitum
- Acclimation period: Approximately 2 weeks

ENVIRONMENTAL CONDITIONS
- Temperature: 20.7 - 23.2°C
- Humidity: 19.96-74.37%
- Air changes (per hr): Not reported
- Photoperiod: 12 hrs dark / 12 hrs light

IN-LIFE DATES: From: 24 November 2003 To: 17 January 2004

Administration / exposure

Route of administration:
inhalation: gas
Type of inhalation exposure:
whole body
Vehicle:
other: air
Remarks on MMAD:
MMAD / GSD: MMAD: 1.607, 1.477, 1.643, 1.428 µm; GSD: 2.045, 2.385, 2.005, 1.897; total mass concentration: 3.04 x 10E-3, 3.24 x10E-3, 3.61xE10-3, 2.69x10E-3 mg/m3 for target exposure concentrations of 0, 1600, 5000 and 16000 ppm respectively.
Details on inhalation exposure:
GENERATION OF TEST ATMOSPHERE / CHAMBER DESCRIPTION
- Exposure apparatus: 1000 L glass and stainless steel whole-body exposure chamber
- Method of holding animals in test chamber: housed individually, the placement of animals in the chamber was rotated daily to ensure uniform exposure
- System of generating particulates/aerosols: the test substance was delivered from a single cylinder, through a regulator and two backpressure gauges via a flowmeter into the exposure chambers
- Time to T99: 23 minutes maximum
- Airflow rate: 204 Lpm
- Temperature and humidity in chamber: 20-24°C, 28-59%
- Oxygen level: at least 19%
- Air flow rate: minimum flow rate of 200 L/minute
- Air change rate: final airflow set to provide at least one air change in 5 mins (12 air changes/hour)
- Method of particle size determination: determined weekly using a TSI Aerodynamic Particle Sizer
- Treatment of exhaust air: filtered through a system which consisted of a coarse filter, a HEPA filter and an activated charcoal bed

TEST ATMOSPHERE
- Brief description of analytical method used: Infrared spectrophotometer (IR) 4 times per chamber per day
- Samples taken from breathing zone: yes
Analytical verification of doses or concentrations:
yes
Details on analytical verification of doses or concentrations:
Exposure levels were determined using an infrared spectrophotometer 4 times/chamber/day. The test substance was evenly distributed within each chamber. The mean (± SD) analytical concentrations were 0.0 ± 0.0, 1599 ± 59, 5186 ± 285 and 16380 ± 626 ppm.
Duration of treatment / exposure:
Males: 2 weeks prior to mating and a minimum of 28 days after mating.
Females: 2 weeks prior to mating and post-mating for an additional 4 weeks.
Frequency of treatment:
6 hours/day, 7 days/week
Doses / concentrationsopen allclose all
Remarks:
Doses / Concentrations:
0, 1600, 5000 and 16000 ppm
Basis:
other: target concentration
Remarks:
Doses / Concentrations:
0.0 ± 0.0, 1599 ± 59, 5186 ± 285 and 16380 ± 626 ppm
Basis:
analytical conc.
No. of animals per sex per dose:
12/sex/group
Control animals:
yes, sham-exposed
Details on study design:
- Dose selection rationale: Based on results of a 2-week range-finding study (HLS Study No. 03-6144) which showed no toxicity at 160, 1600 and 16000 ppm). The high level was established at 16000 ppm since it is 50% of the lower explosion limit for the test substance.

Examinations

Observations and examinations performed and frequency:
CAGE SIDE OBSERVATIONS: Yes
- Time schedule: twice daily (mortality and clinical condition)

DETAILED CLINICAL OBSERVATIONS: Yes
- Time schedule: Weekly

BODY WEIGHT: Yes
- Time schedule for examinations: At randomisation, first day of exposure and weekly thereafter.

FOOD CONSUMPTION: Yes
- Time schedule for examinations: Pre-test and weekly thereafter.

WATER CONSUMPTION: No

OPHTHALMOSCOPIC EXAMINATION: No

HAEMATOLOGY: Yes
- Time schedule for collection of blood: Study termination
- Anaesthetic used for blood collection: Yes (CO2/O2)
- Animals fasted: Yes (overnight)
- How many animals: 12/sex/group
- Parameters examined: haemoglobin concentration, haematocrit, erythrocyte count, platelet count, mean corpuscular volume, mean corpuscular haemoglobin, mean corpuscular haemoglobin concentration, total leukocyte count, reticulocyte count, differential leukocyte count, erythrocyte and platelet morphology (from peripheral blood smear), prothrombin time, activated partial thromboplastin time..

CLINICAL CHEMISTRY: Yes
- Time schedule for collection of blood: Study termination
- Anaesthetic used for blood collection: Yes (CO2/O2)
- Animals fasted: Yes (overnight)
- How many animals: 12/sex/group
- Parameters examined: aspartate aminotransferase, alanine aminotransferase, alkaline phosphatase, blood urea nitrogen, creatinine, glucose, cholesterol, total protein, triglycerides, albumin, total bilirubin, sodium, potassium, chloride, calcium, inorganic phosphorus, gamma-glutamyl transpeptidase, globulin, albumin/globulin ratio

URINALYSIS: No

NEUROBEHAVIOURAL EXAMINATION: Yes
- Time schedule for examinations: During last week of exposure
- Dose groups that were examined: All
- Battery of functions tested: sensory observations (startle response to auditory stimuli, tail pinch response), neuromuscular observations (grip strength - hindlimb and forelimb), physical observations (rectal temperature) and motor activity assessments

Sacrifice and pathology:
GROSS PATHOLOGY: Yes (all animals)
- examined: external surfaces, all orifices, cranial cavity, nasal cavity, neck and its associated tissues and organs, thoracic, abdominal and pelvic cavities and their associated tissues and organs and external surfaces of the brain.
ORGAN WEIGHTS: Yes (all animals)
- organs weighed: adrenal glands, brain, epididymes, heart, kidneys, liver, lungs (with mainstem bronchi), ovaries (with oviducts), spleen, testes, thymus, uterus with vagina.
HISTOPATHOLOGY: Yes (control and high dose only).
- tissues examined: adrenal glands, bone (sternum/femur), brain (cerebellum, cerebrum and cerebellum), epididymes, heart, kidneys, large intestine (caecum, colon and rectum), liver, lungs (with mainstream bronchi), lymph node (mesenteric), lymph node (mediastinal), mammary glands (with adjacent skin), ovaries (with oviducts), prostate, seminal vesicles, small intestine (duodenum, ileum and jejunum), spinal cord (cervical, thoracic and lumbar), spleen, stomach, testes, thymus, thyroids with parathyroids, tibial nerve, trachea, urinary bladder, uterus with vagina, all macroscopic lesions and tissue masses.
Statistics:
Group mean values of parameters for all the exposure groups were compared to the control group mean values at each time interval, using appropriate statistical methods.

Results and discussion

Results of examinations

Clinical signs:
no effects observed
Mortality:
no mortality observed
Body weight and weight changes:
no effects observed
Food consumption and compound intake (if feeding study):
effects observed, treatment-related
Haematological findings:
no effects observed
Clinical biochemistry findings:
no effects observed
Behaviour (functional findings):
no effects observed
Organ weight findings including organ / body weight ratios:
no effects observed
Gross pathological findings:
no effects observed
Histopathological findings: non-neoplastic:
no effects observed
Details on results:
No systemic toxicity (no effects on survival, haematological or clinical chemistry parameters, food consumption, body weight, organ weight, and histopathology) or neurological effects (as measured by clinical observations, functional observational battery, and motor activity) were observed.

Marginally lower food consumption at 16000 ppm compared to controls was seen during 1st week of exposure, but differences from control were less than 5% and were transient and, therefore, were considered not to be adverse.

Effect levels

open allclose all
Dose descriptor:
NOAEC
Remarks:
systemic toxicity
Effect level:
16 000 ppm
Sex:
male/female
Basis for effect level:
other: highest concentration tested
Dose descriptor:
NOAEC
Remarks:
systemic toxicity
Effect level:
19 678 mg/m³ air
Sex:
male/female
Basis for effect level:
other: highest concentration tested

Target system / organ toxicity

Critical effects observed:
not specified

Any other information on results incl. tables

No systemic toxicity (no effects on survival, haematological or clinical chemistry parameters, food consumption, body weight, organ weight, and histopathology) or neurological effects (as measured by clinical observations, functional observational battery, and motor activity) were observed.

Applicant's summary and conclusion

Conclusions:
No systemic toxicity (no effects on survival, haematological or clinical chemistry parameters, feed consumption, body weight, organ weight, and histopathology) or neurological effects (as measured by clinical observations, functional observational battery, and motor activity) were observed.

The no observed adverse effect concentration (NOAEC) of ethane was 16000 ppm in this study. Equivalent to 19678 mg/m3
Executive summary:

The study assessed the potential toxicity, including neurotoxicity and reproductive performance in male and female rats following ethane exposure at 1600, 5000and 16000 ppm (highest exposure level was 50% of the lower explosive limit). It also was designed to investigate effects in both sexes on mating behaviour and on gonadal function, as well as effects on conception, development, parturition and pup survival to lactation day 4.

Male and female rats were exposed for 6 hours/day, 7 days/week for 2 weeks prior to mating initiation. Main study males and females were then evaluated for subchronic effects and were exposed once daily (6 hours/day), seven days/week for 4 weeks (28 days).

There was no effect on survival. There were no exposure-related clinical effects or effects on body weight, food consumption, FOB or motor activity parameters for either sex (except the16000 ppm exposed animals showed marginally lower food consumption during the first week of exposures).There were no exposure-related differences in haematology, clinical chemistry and no macroscopic or microscopic changes at post-mortem.

Exposure of male and female rats to target concentrations of 1600, 5000 or 16000 ppm of ethane by whole-body inhalation for 4-6 weeks resulted in no general systemic or neurotoxic effects apart from a very marginal reduction of food consumption during the first week of exposure at 16000 ppm and this transient difference was not considered adverse.

A no-observed-adverse effect concentration (NOAEC) of 16000 ppm was determined for all endpoints. Equivalent to 19678 mg/m3 (mw 30.07g/mol).