Hydrocarbons, C4, 1,3-butadiene- and isobutene-free

Repeated dose toxicity: inhalation

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

Study period:

2003 - 2008 (date final report signed by Study Director)

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: GLP compliant (except for test substance identity, stability and lot number), guideline study, available as unpublished report, no restrictions, fully adequate for assessment

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2008

Report date:

2008

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:

no

Test guideline 2

Qualifier:

according to guideline

Guideline:

other: EPA OPPTS 870.3650 (Combined repeated exposure toxicity study with the Reproduction/Developmental toxicity screening test)

GLP compliance:

yes

Remarks:

The identity and stability was not in compliance with GLP regulations. The lot number was not available.

Limit test:

no

Test material

Test material information

Constituent 1

Reference substance name:

Butane

EC Number:

203-448-7

EC Name:

Butane

Cas Number:

106-97-8

Molecular formula:

C4H10

IUPAC Name:

butane

Details on test material:

- Name of test material (as cited in study report): butane
- Physical state: colourless gas
- Analytical purity: 99.5% per supplier
- Analytical purity: 99.23% before study, 99.98% after study
- Lot/batch No.: not available
- Expiration date of the lot/batch: not available
- Stability under test conditions: confirmed
- Storage condition of test material: Ambient
- Other: An archival sample was stored.

Test animals

Species:

rat

Strain:

other: Sprague-Dawley CD

Sex:

male/female

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Source: Charles River Laboratories, Raleigh, North Carolina 27610
- Age at study initiation: Approximately 8 weeks
- Weight at study initiation: males: 241-280 g (mean: 261 g); females 174-229 g (mean 200 g)
- Fasting period before study: none
- Housing: Individually in stainless steel suspended cages with wire mesh floors and fronts
- Diet: Certified Rodent Diet # 5002 (PMI Nutrition Int., St. Louis, Missouri) ad libitum
- Water: ad libitum
- Acclimation period: Approximately 2 weeks

ENVIRONMENTAL CONDITIONS
- Temperature 20.7-22.4°C
- Humidity: 24.28-77.36%
- Air changes (per hr): no data
- Photoperiod: 12 hrs dark / 12 hrs light

IN-LIFE DATES: From: 29 September 2003 To: 26 April 2006

Administration / exposure

Route of administration:

inhalation

Type of inhalation exposure:

whole body

Vehicle:

other: air

Remarks on MMAD:

MMAD / GSD: MMAD: 4.335, 4.737, 2.455 and 3.503 µm; GSD: 2.124, 2.100, 1.989 and 2.028; total mass concentration: 3.62 x 10E-3, 3.45 x10E-3, 2.94xE10-3, 3.18x10E-3 mg/m3 for target exposure concentrations of 0, 900, 3000 and 9000 ppm respectively.

Details on inhalation exposure:

Not detailed in main report, require access to Appendix II, Volume 3

GENERATION OF TEST ATMOSPHERE / CHAMBER DESCRIPTION
- Exposure apparatus: Whole-body inhalation chamber
- Method of holding animals in test chamber: Individually in stainless steel suspended cages with wire mesh floors and fronts
- Source and rate of air:
- Method of conditioning air:
- System of generating particulates/aerosols:
- Temperature, humidity, pressure in air chamber:
- Air flow rate:
- Air change rate:
- Method of particle size determination: yes
- Treatment of exhaust air:

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, 930.6 ± 28.1, 3022 ± 58 and 9157 ± 269 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, 900, 3000 and 9000 ppm
Basis:
other: target concentration

Doses / concentrations 2

Remarks:

Doses / Concentrations:
0.0 ± 0.0, 930.6 ± 28.1, 3022 ± 58, 9157 ± 269 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 the results of a 2-week range-finding study (HLS study # 03-6143) which showed no toxicity at exposure levels of 90, 900 and 9000 ppm. The highest exposure level was established (for safety reasons) at 9000 ppm since it was 50% of the lower explosion limit (1.8% = 18000 ppm).

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: All animals examined prior to randomisation and once weekly throughout the study.

BODY WEIGHT: Yes
- Time schedule for examinations: Once weekly throughout the study. Animals were fasted prior to the recording of terminal bodyweights.

FOOD CONSUMPTION: Yes
- Time schedule for examinations: Once weekly throughout the study.

WATER CONSUMPTION: No

OPHTHALMOSCOPIC EXAMINATION: No

HAEMATOLOGY: Yes. Haematology in control and high dose animals
- Time schedule for collection of blood: at study termination.
- Anaesthetic used for blood collection: Yes (CO2/O2)
- Animals fasted: Yes, overnight prior to blood collection
- 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 examined (from peripheral blood smear).

CLINICAL CHEMISTRY: Yes. Clinical pathology in control and high dose animals
- Time schedule for collection of blood: at study termination.
- Anaesthetic used for blood collection: Yes (CO2/O2)
- Animals fasted: Yes, overnight prior to blood collection
- How many animals: 12/sex/group
- Parameters examined: Prothrombin time, activated partial thromboplastin time, 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 and albumin/globulin ratio.

URINALYSIS: No

NEUROBEHAVIOURAL EXAMINATION: Yes
- Time schedule for examinations: during the last week of exposure
- Dose groups that were examined: all main study animals
- Battery of functions tested: sensory observations, neuromuscular observations, physical observations and motor activity assessments

Sacrifice and pathology:

GROSS PATHOLOGY: Yes (all animals)
ORGAN WEIGHTS: Yes (all animals). Adrenal glands, brain, epididymides, heart, kidneys, liver, lungs, ovaries, spleen, testes, thymus and uterus with vagina.
HISTOPATHOLOGY: Yes (control and high dose only). Tissues examined: adrenal glands, bone (sternum/femur), bone marrow, brain (medulla/pons, cerebrum and cerebellum), epididymides, heart, kidneys, caecum, colon, rectum, larynx, liver, lungs (with mainstem bronchi), lymph nodes (mesenteric and mediastinal), mammary glands (with adjacent skin), nasopharynx, ovaries (with oviducts), prostate, seminal vesicles, duodenum, ileum, jejunum, spinal cord (cervical, thoracic and lumbar), spleen, stomach, testes, thymus, thyroid with parathyroids, tibial nerve, trachea, urinary bladder, uterus with vagina and 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):

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 systemic toxicity (e.g., no affect 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.

Effect levels

1

Dose descriptor:

NOAEC

Remarks:

systemic toxicity

Effect level:

9 000 ppm

Sex:

male/female

Basis for effect level:

other: No effects observed at the highest concentration tested.

2

Dose descriptor:

NOAEC

Remarks:

systemic toxicity

Effect level:

21 394 mg/m³ air

Sex:

male/female

Basis for effect level:

other: No effects observed at the highest concentration tested.

Target system / organ toxicity

Critical effects observed:

no

Applicant's summary and conclusion

Conclusions:

Exposure of male and female rats to target concentrations of 900, 3000 and 9000 ppm of butane resulted in no general systemic toxicity (i.e., no affect 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).
A no observed adverse effect concentration (NOAEC) of 9000 ppm was determined for this study's systemic endpoints. Equivalent to 21394 mg/m3.

Executive summary:

This study assessed the potential toxicity, including neurotoxicity and reproductive performance in male and female rats following butane exposure at 900, 3000 and 9000 ppm.

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 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 systemic effects or effects on body weight, food consumption, FOB or motor activity parameters in either sex. Furthermore there were no exposure-related differences in haematology, clinical chemistry and no macroscopic or microscopic changes at post-mortem.

A no observed adverse effect concentration (NOAEC) of 9000 ppm was determined for this study's systemic, reproductive, and neonatal endpoints. Equivalent to 21394 mg/m3 (MW 58.12g/mol).