Hydrocarbons, C3-4

Repeated dose toxicity: inhalation

Administrative data

Endpoint:

short-term repeated dose toxicity: inhalation

Remarks:

combined repeated dose and reproduction / developmental screening

Type of information:

experimental study

Adequacy of study:

key study

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: GLP compliant (minor exception listed below), guideline study, available as unpublished report, no restrictions, fully adequate for assessment.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:

2009

Report date:

2009

Materials and methods

Test guideline

Test guideline 1

Qualifier:

according to guideline

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

Test guideline 2

Qualifier:

according to guideline

Guideline:

other: OPPTS 870.3650 (Combined Repeated Dose Toxicity Study with the Reproduction / Developmental Toxicity Screening Test)

GLP compliance:

yes

Limit test:

no

Test material

Test material information

Constituent 1

Reference substance name:

Propane

EC Number:

200-827-9

EC Name:

Propane

Cas Number:

74-98-6

Molecular formula:

C3H8

IUPAC Name:

propane

Details on test material:

- Name of test material (as cited in study report): propane
- Supplier: MG Industries, 3 Great Valley Parkway, Malvern, Pennsylvania 19355, USA
- Substance type: Industrial gas
- Physical state: colourless gas
- Analytical purity: 99.5% per supplier
- Lot/batch No.: Not available
- Stability under test conditions: 99.91% before study, 99.90% after study
- Storage condition of test material: Ambient

Test animals

Species:

rat

Strain:

other: Sprague-Dawley CD

Sex:

male/female

Details on test animals or test system 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 269 g (range 243-297 g); females mean 200 g (range 180-220 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 except during exposure
- Water: Municipal water ad libitum except during exposure
- Acclimation period: Approximately 2 weeks

ENVIRONMENTAL CONDITIONS
- Temperature: 20.1 - 25.7°C
- Humidity: 18.22-92.93%
- Air changes (per hr): Not reported
- Photoperiod: 12 hrs dark / 12 hrs light

IN-LIFE DATES: From: 19 January 2004 To: 18 February 2004

Administration / exposure

Route of administration:

inhalation

Type of inhalation exposure:

whole body

Vehicle:

other: air

Remarks on MMAD:

MMAD / GSD: MMAD: 2.273, 2.541, 4.061, 6.560 µm; GSD: 1.994, 2.015, 1.981, 2.187; total mass concentration: 3.53 x 10E-3, 4.32 x10E-3, 9.96xE10-3, 1.58x10E-3 mg/m3 for target exposure concentrations of 0, 1200, 4000 and 12000 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: no data
- Airflow rate: no data
- Temperature and humidity in chamber: no data
- Oxygen level: no data
- Air flow rate: no data
- Air change rate: no data
- 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) analaytical concentrations were 0.0 ± 0.0, 1230 ± 34, 3990 ± 156, and 12168 ± 415 ppm.

Duration of treatment / exposure:

Males: 2 weeks prior to mating and after post-mating to give a minimum 28 day exposure period.
Females: 2 weeks prior to mating and post-mating for an additional 4 weeks.

Frequency of treatment:

6 hours/day, 7 days/week

Doses / concentrations

Doses / concentrations 1

Remarks:

Doses / Concentrations:
0, 1200, 4000 and 12000 ppm
Basis:
other: target concentration

Doses / concentrations 2

Remarks:

Doses / Concentrations:
0.0 ± 0.0, 1230 ± 34, 3990 ± 156, 12168 ± 415 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. 03-6146) which showed no toxicity at 120, 1200 and 12000 ppm). The high level was established at 12000 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:

effects observed, treatment-related

Description (incidence and severity):

Exposure-related 25% decrease in weight gain during the first week of exposures and this difference persisted for the remainder of the 4 weeks of exposure.

Food consumption and compound intake (if feeding study):

no effects observed

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 neurological, haematological, or clinical chemistry effects were observed. There was a 25% decrease in body weight gain in males exposed to 12000 ppm during the first week of exposure which persisted for the remainder of the 4 weeks exposure.

Effect levels

1

Dose descriptor:

NOAEC

Remarks:

overall systemic toxicity

Effect level:

4 000 ppm

Sex:

male/female

Basis for effect level:

other: based on a reduction of bodyweight gain in males at 12000 ppm.

2

Dose descriptor:

NOAEC

Remarks:

overall systemic toxicity

Effect level:

7 214 mg/m³ air

Sex:

male/female

Basis for effect level:

other: based on a reduction of bodyweight gain in males at 12000 ppm.

3

Dose descriptor:

LOAEC

Effect level:

12 000 ppm

Sex:

male/female

Basis for effect level:

other: based on a reduction of bodyweight gain in males at 12000 ppm.

4

Dose descriptor:

LOAEC

Effect level:

21 641 mg/m³ air

Sex:

male/female

Basis for effect level:

other: based on a reduction of bodyweight gain in males at 12000 ppm.

Target system / organ toxicity

Critical effects observed:

not specified

Applicant's summary and conclusion

Conclusions:

No general systemic or neurological, haematological, or clinical chemistry effects were observed except for a 25% decrease in body weight gain in males exposed to 12000 ppm during the first week of exposure which persisted for the remainder of the 4 weeks exposure.

The overall NOAEC of propane was 4000 ppm and the LOAEC was 12000 ppm in this study.

Executive summary:

The study assessed the potential toxicity, including neurotoxicity and reproductive performance in male and female rats following butane exposure at 1200, 4000 and 12000 ppm (highest exposure level is 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 of treatment on survival. There were no exposure-related systemic effects or effects on body weight, except the 12000 ppm exposed male animals showed an exposure-related 25% decrease in weight gain during the first week of exposures and this difference persisted for the remainder of the 4 weeks of exposure. There were no exposure-related effects on food consumption, functional observation battery (FOB) or motor activity parameters for either sex. Furthermore 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 1200, 4000 or 12000 ppm of propane by whole-body inhalation for 4-6 weeks resulted in no general systemic/neurotoxic effects, apart from a reduction of body weight gain in the males resulting from the exposures at 12000 ppm.

The authors report an overall no-observed-adverse effect concentration (NOAEC) of 4000 ppm for general systemic/neurotoxic endpoints in this study, this was based on reduced bodyweight gain in males during the first week. No bodyweight effects were seen in females.

Therefore:

Overall NOAEC both sexes 4000 ppm (equivalent to 7214 mg/m3 (mw 44.094g/mol)) for general systemic/neurotoxic endpoints in this study, based on reduced bodyweight gain in males during the first week.

NOAEC males 4000 ppm (equivalent to 7214 mg/m3) based on reduced bodyweight gain at 12000 ppm during the first week.

NOAEC females 120000 ppm (equivalent to 21641 mg/m3).