Registration Dossier

Administrative data

Endpoint:
acute toxicity: inhalation
Type of information:
migrated information: read-across from supporting substance (structural analogue or surrogate)
Adequacy of study:
key study
Study period:
2000-04-04 to 2000-07-4
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
other: This study is classified as reliable without restriction because it was conducted according to or similar to guideline study OECD TG 403.

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
2000

Materials and methods

Test guideline
Qualifier:
according to
Guideline:
OECD Guideline 403 (Acute Inhalation Toxicity)
GLP compliance:
yes
Remarks:
GLP statement is not signed.
Test type:
standard acute method

Test material

Reference
Name:
Unnamed
Type:
Constituent
Type:
Constituent
Test material form:
other: mixed aerosol/vapour
Details on test material:
- Name of test material (as cited in study report): Bitumen fumes generated from a sample of bitumen tank condensate (particulate and vapour)
- Substance type: Bitumen
- PAH and Total Hydrocarbon Content in exposure atmosphere detailed in attachment:

Test animals

Species:
rat
Strain:
Wistar
Sex:
male/female
Details on test animals and environmental conditions:
TEST ANIMALS
- Source: Charles River Deutschland Sulzfeld, Germany
- Age at study initiation: Approximately 7 weeks of age
- Weight at study initiation: Not reported
- Fasting period before study: Not reported
- Housing: Individually in polycarbonate type III cages.
- Diet (e.g. ad libitum): Ad libitum (not offered during exposure period)
- Water (e.g. ad libitum): Ad libitum (not offered during exposure period)
- Acclimation period: Three weeks

ENVIRONMENTAL CONDITIONS
- Temperature (°C): 22 degrees Celsius
- Humidity (%): 30% to 70%
- Air changes (per hr): 12 to 15 times per hour
- Photoperiod (hrs dark / hrs light): 12 hours dark/ 12 hours light.

Administration / exposure

Route of administration:
other: mixed aerosol and vapour
Type of inhalation exposure:
nose only
Vehicle:
other: unchanged (no vehicle)
Details on inhalation exposure:
GENERATION OF TEST ATMOSPHERE / CHAMBER DESCRIPTION
- Exposure apparatus: Cylinder in tapered acrylic glass tube
- Exposure chamber volume: 250 mL
- Method of holding animals in test chamber: Not reported
- Source and rate of air: Not reported
- Method of conditioning air: Not reported
- System of generating particulates/aerosols: Droplet spray was generated and the droplets were evaporated in a heating tube. The hot vapour issued through a nozzle into a slowly flowing cool air stream surrounding the jet.
- Method of particle size determination: scanning mobility particle size sizer
- Treatment of exhaust air: Not reported
- Temperature, humidity, pressure in air chamber: 23.8 +/- 0.5 degrees Celsius, 48.2% +/- 2.1 humidity

TEST ATMOSPHERE
- Brief description of analytical method used:
- Samples taken from breathing zone: Yes

VEHICLE - No vehicle was used.

TEST ATMOSPHERE (if not tabulated)
- Particle size distribution: 7 to 300 nm
- MMAD (Mass median aerodynamic diameter) / GSD (Geometric st. dev.): Number median aerodynamic diameter using a SMPS was 85 nm
Analytical verification of test atmosphere concentrations:
yes
Duration of exposure:
4.5 h
Remarks on duration:
an additional 30 min was necessary to reach the target concentration.
Concentrations:
100 mg/m3 could not be met at the beginning of the exposure time. The actual concentration measured during the following four hour period was 94.4 mg/m3.
No. of animals per sex per dose:
5 male and 5 females
Control animals:
yes
Details on study design:
- Duration of observation period following administration: 14 days
- Frequency of observations and weighing: Several times on the exposure day and daily thereafter.
- Necropsy of survivors performed: Yes
-Other: Body temperature and reflex testing was performed.
Statistics:
Differences in rectal temperature, body weight and body weight gain between groups were considered case by case as statistically significant at the level of p< 0.05. The t-test was used.

Results and discussion

Effect levels
Sex:
male/female
Dose descriptor:
LC50
Effect level:
> 94.4 mg/m³ air
Exp. duration:
4.5 h
Remarks on result:
other: mixed aerosol and vapour
Clinical signs:
No signs of clinical intoxication were observed.
Body weight:
No influence on body weight was observed.
Gross pathology:
No abnormalities which could be related to treatment were detected in the control group or the exposure group.
Other findings:
In both exposure groups male and female body temperatures were significantly lower after the end of the exposure.

Any other information on results incl. tables

The only difference observed between exposed and controls, was a slight decrease in body temperature in the exposed animals (35.6 and 36.6°C in males and females, respectively) compared with the controls (37.3 and 37.7°C in males and females, respectively). None of the investigated reflexes had been influenced by the treatment at any timepoint.

Applicant's summary and conclusion

Interpretation of results:
not classified
Remarks:
Migrated information Not classified under CLP (EC 1272/2008) Criteria used for interpretation of results: EU
Conclusions:
The exposure was tolerated by all rats with no signs of intoxication. No mortality occurred. In both exposure groups males and females experienced slight but significantly lower body temperatures after the end of the exposure, compared to the control value.
Executive summary:

At ambient temperature bitumens are solid or semi-solid. For most applications, materials are handled at elevated temperatures which makes thermal burns the greatest acute hazard. No acute inhalation toxicity data are available for straight-run bitumen but a study has been performed on an oxidized (air-rectified) asphalt which is used for read across. Read across of oxidised asphalt to straight run bitumen is considered valid since mild oxidation is not expected to change the composition or acute toxicity of the material.

Fume from oxidized (air-rectified asphalt) was tested in an OECD 403 study under GLP conditions (Fraunhofer, 2000). The fumes were collected from storage tanks containing commercial product, condensed and regenerated in the laboratory under well defined conditions. Wistar rats (5 males and 5 females) were nose-only exposed to regenerated fume or clean air for 4.5 h (half an hour longer than the standard 4 h to achieve the desired exposure concentration during 4 h) and subsequently housed individually for 2 weeks. The exposure concentration was 94.4±7.7 mg/m3 as total hydrocarbon with a number median aerodynamic diameter (NMAD) as measured with the SMPS - system (scanning mobility particle seizer) of 85 nm. All animals were observed for clinical and behavioural signs during the exposure, several times after the termination of exposure on the day of exposure and daily on all the subsequent days. Body weights were recorded on day 0, 3, 7 and 14. At the end of the study the animals were sacrificed and subject to gross pathology. No clinical signs of intoxication were observed at any time. No effects on any of the reflexes tested were observed at any time. Also no differences in body weight were observed between exposed and controls nor were any gross abnormalities found upon necropsy. The only difference observed between exposed and controls, was a slight decrease in body temperature in the exposed animals (35.6 and 36.6°C in males and females, respectively) compared with the controls (37.3 and 37.7°C in males and females, respectively). The LC50 was found to be > 94.4 mg/m3 (4 hours).

 

This study received a Klimisch score of one and is classified as reliable with restriction because it was conducted according to or similar to guideline study OECD TG 403.