Asphalt, sulfonated, sodium salt

Acute Toxicity: inhalation

Administrative data

Endpoint:

acute toxicity: inhalation

Type of information:

experimental study

Adequacy of study:

key study

Study period:

19 February 2014 to 25 April 2014

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2014

Report date:

2014

Materials and methods

Test guideline

Test guideline 1

Qualifier:

according to guideline

Guideline:

OECD Guideline 403 (Acute Inhalation Toxicity)

Version / remarks:

2009

Deviations:

no

Test guideline 2

Qualifier:

according to guideline

Guideline:

EPA OPPTS 870.1300 (Acute inhalation toxicity)

Version / remarks:

1998

Deviations:

no

GLP compliance:

yes

Test type:

traditional method

Limit test:

yes

Test material

Test material information

1

Reference substance name:

Asphalt, sulfonated, sodium salt

EC Number:

269-212-0

EC Name:

Asphalt, sulfonated, sodium salt

Cas Number:

68201-32-1

Molecular formula:

UVCB

IUPAC Name:

Asphalt, sulfonated, sodium salt

Test material form:

solid: particulate/powder

Specific details on test material used for the study:

STABILITY AND STORAGE CONDITIONS OF TEST MATERIAL
- Storage condition of test material: at room temperature
- Stability under test conditions: not specified
- Reactivity of the test substance with the solvent/vehicle of the cell culture medium: not applicable

TREATMENT OF TEST MATERIAL PRIOR TO TESTING
- Treatment of test material prior to testing: not specified
- Preliminary purification step (if any): not specified

Test animals

Species:

rat

Strain:

Crj: CD(SD)

Sex:

male/female

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Source: Charles River Laboratories, USA
- Females (if applicable) nulliparous and non-pregnant: not specified
- Age at study initiation: 9 weeks old
- Weight at study initiation: 317 - 346 g males, 225 - 248 g for females.
- Fasting period before study: none
- Housing: All animals were housed individually in suspended wire-mesh cages.
- Diet: A certified feed with appropriate analysis performed by the manufacturer, ad libitum. No contaminants were present in animal feed.
- Water: Reverse osmosis-treated water supplying the facility, ad libitum. No contaminants were present in water.
- Acclimation period: 7 days

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

Administration / exposure

Route of administration:

inhalation: dust

Type of inhalation exposure:

nose only

Vehicle:

air

Mass median aerodynamic diameter (MMAD):

3.4 µm

Geometric standard deviation (GSD):

2.85

Details on inhalation exposure:

GENERATION OF TEST ATMOSPHERE / CHAMBER DESCRIPTION
- Exposure apparatus: The exposure was conducted using a 7.9 - L stainless steel, convensional nose-only exposure system with synthetic rubber grommets in exposure ports to engage the animal holding tubes.
- Exposure chamber volume: 7.9 L
- Method of holding animals in test chamber: Animals were restrained in nose-only exposure holding tubes during exposure.
- Source and rate of air: Airflow rates through the system were determined from the aerosol generation and the dilution airflow and provided a minimum of 12 air changes per hour through the exposure system. Airflow through the exposure system was provided using a dry, breathing quality , in-house, compressed air source. Exposure atmosphere environmental conditions were recorded at approximately 60-minute intervals during the exposure. Dry compressed air was supplied to the micronizing and inlet ports of the jet mill using 2 regulators. The resulting aerosol from the jet mill was delivered to a 4.8L glass chromatography jar and then to a "T"-fitting at the inlet of the nose-only exposure system through 22-mm corrugated respiratory tubing.
- Method of conditioning air: At the "T-fitting, humidified dilution air was added using a Coilhose Pneumatics regulator. The flow of dilution air was controlled using a rotameter-type flowmeter. Humidified dilution air was produced by passing dry compressed air through a muffler-type bubbler submerged in a 2-L Erlenmeyer flask filled with DI water.
- System of generating particulates/aerosols: A dust aerosol atmosphere of the test substance was generated. The test substance was delivered using an auher-type feeder which fed test substance at a constant rate to a jet mill air micronizer operating as a particle size reduction and dispersion device. The AccuRate feeder was equipped with a 3/8-inch solid core auger. The feeder and jet mill were equipped with Syntron magnetic vibrators.
- Method of particle size determination: Four aerosol particle size measurements were conducted during exposure using a 7-stage cascade impactor. Pre-weighed, 25 mm glass-fiber filters were used as the collection substances. Samples were collected at 1.8 L/minute for 0.25 minutes. The filters were re-weighed and the particle size was calculated based on the impactor stage cut-offs.
- Treatment of exhaust air: Exhaust atmosphere was filtered using a Solberg filter prior to entering the in-house exhaust system which included activated charcoal- and HEPA-filtration.
- Temperature, humidity, pressure in air chamber: A temperature and relative humidity transmitter probe was used with a display unit to monitor temperature and percent relative humidity. Oxigen content was measured during the pre-exposure method development phase using a Drager PAC III equipped with a calibrated oxygeb sensor.

TEST ATMOSPHERE
- Brief description of analytical method used: Actual exposure concentrations were determined using standard gravimetric methods. Samples were collected on pre-weighed, 25-mm glass fiber filters held in a closed-faced filter holder positioned in the animal exposure port of the nose-only exposure system. A measured volume of the exposure atmosphere was pulled through the filter to quantitatively collect aerosol particles. Following sample collection, the filters were re-weighed and the concentration calculated as the filter weight difference divided by the sample volume. Samples were collected at approximately 1L/ minute for 0.5 minutes.
- Samples taken from breathing zone: yes


TEST ATMOSPHERE (if not tabulated)
- Particle size distribution: Particle size distribution was calculated based on the impactor stage cut-offs.
- MMAD (Mass median aerodynamic diameter) / GSD (Geometric st. dev.): The aerosol size was expressed as the mass median aerodynamic diameter (MMAD) and the geometric standard deviation (GSD). Three of the particle size measurements were used to calculate the mean particle size for the exposure. The second sample was excluded due to a sampling error in which a large bolus of test material was inadvertently drawn into the impactor during sampling.

CLASS METHOD (if applicable)
- Rationale for the selection of the starting concentration: inhalation exposure as a dust aerosol at a concentration of 5.3 mg/L

Analytical verification of test atmosphere concentrations:

yes

Duration of exposure:

4 h

Concentrations:

Target exposure concentration: 5 mg/L
Actual exposure concentration: 5.3 mg/L
Nominal concentration: 18.2 mg/L

No. of animals per sex per dose:

10 males and 10 females

Control animals:

yes

Details on study design:

- Duration of observation period following administration: 14 days
- Frequency of observations and weighing: Each animal was observed for mortality at the approximate midpoint of exposure. Thereafter, all recovery animals were observed for mortality and moribundity twice daily during the study period. Body weights were obtained prior to exposure on study day 0 for all animals and on post-exposure days 3, 7, and 14 for recovery animals.
- Necropsy of survivors performed: yes. Necropsies were conducted on 5 animals/sex after exposure (primary necropsy) and on 5 animals/sex after a 14-day non-exposure recovery period (recovery necropsy).
- Other examinations performed: clinical signs, body weight,organ weights, histopathology (lungs)

Results and discussion

Effect levels

Key result

Sex:

male/female

Dose descriptor:

LC50

Effect level:

> 5.3 mg/L air

Based on:

test mat.

Exp. duration:

4 h

Mortality:

None of the animals died during the exposure or during the 14-day study period.

Clinical signs:

other: Partial exposure of the left or right eye was observed for 3 females and 2 females, respectively, immediately after exposure. Partial closure of the left eye was observed for 1 female at the 2-hour post-exposure observation period. Brown material on the f

Body weight:

All recovery animals surpassed their initial body weight by study day 14 and were considered normal.

Gross pathology:

Mottled lungs or brown discolouration of the lungs were noted in all of the test animals in the primary and recovery necropsies. This correlated with the presence of brown pigment within the lungs. Brown matting of the skin and dark red contents of the stomach were noted in males and females from the study day 0 primary necropsy. This was considered to be related to test substance exposure due to the high insidence of observation.

Other findings:

- Organ weights: Mean lung weights and most individual animal lung weights for animals from the study day 0 primary necropsy were within the WIL Research historical control data range. Lung weights of the test substance-exposed males and females at the study day 14 recovery necropsy were higher than the range of the WIL Research historical control data, including both the group mean values and many individual animal values.
- Histopathology: Microscopic findings considered to be associated with test substance exposure were noted in the lungs of males and females from the primary and recovery necropsies. Brown granular consistent with particulate matter pigment was present within the lungs of all animals from the primary and recovery necropsies. This finding was of a similar severity in animals from the primary and recovery necropsies, but was present in different locations of the lung tissue. The particulate matter was present free within the air spaces, as well as within the alveolar macrophages and was scattered throughout the section including within large bronchioles and bronchi. In animals from the recovery necropsy, the particulate matter was predominantly within alveolar macrophages and located within small bronchioles or alveoli. This pattern of distribution would be expected with normal functioning of alveolar macrophages in clearing particulate matter from the lung. Epithelial degeneration was observed within the bronchioles of animals from the primary necropsy. This change consisted of loss of cilia and attenuation or rounding of cells with blebbing of the apical cytoplasm and/or shedding of cells into the bronchiolar lumen. This change was not observed in animals from the recovery necropsy, indicating reversibility. Several components of acute inflammation were observed within the lungs of animals from the primary necropsy, including neutrophilic infiltrate within the interstitium, edema, and hemorrhage. These changes were also observed in some animals from the recovery necropsy but were seen at a lower incidence and severity. Atelectasis was present within the lungs of all animals but was more severe in animals from the primary necropsy.

Applicant's summary and conclusion

Interpretation of results:

GHS criteria not met

Conclusions:

In the acute inhalation toxicity study, conducted according to OECD TG 403 and in compliance with GLP, the reported LC50 value was greater than 5.3 mg/L air. Exposure resulted in mottling or brown discoloration of the lungs, which persisted after a 14-day non-exposure (recovery) period. Exposure also resulted in brown matting of the skin and dark red contents in the stomach, which resolved during the recovery period. Higher lung weights were noted after the 14-day non-dosing recovery period.