Ashes (residues), cenospheres

Endpoint summary

Description of key information

Based on read-across following an analogue approach:

Oral: LD50 (rat) > 2000 mg/kg bw

Inhalation: LC50 (rat) > 1400 mg/m³ (respirable fraction), > 5000 mg/m³ (total ashes (residues), cenospheres)

Dermal: no study available

Key value for chemical safety assessment

Acute toxicity: via oral route

Link to relevant study records

Reference

Endpoint:

acute toxicity: oral

Type of information:

migrated information: read-across from supporting substance (structural analogue or surrogate)

Adequacy of study:

key study

Study period:

07 Jan 2008 - 22 Jan 2008

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: see 'Remark'

Remarks:

GLP - Guideline study. In accordance to the ECHA guidance document “Practical guide 6: How to report read-across and categories (March 2010)”, the reliability was changed from RL1 to RL2 to reflect the fact that this study was conducted on a read-across substance.

Qualifier:

according to guideline

Guideline:

EU Method B.1 tris (Acute Oral Toxicity - Acute Toxic Class Method)

Deviations:

no

GLP compliance:

yes

Test type:

acute toxic class method

Limit test:

yes

Species:

rat

Strain:

Wistar

Sex:

female

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Source: Breeding farm BioTest s.r.o., Konárovice, 281 25, CZ, RČH CZ 21760152
- Age at study initiation: 8-10 weeks
- Weight at study initiation: 158-170 g (see table No. 1)
- Fasting period before study: About 20 hours prior to oral administration the animals were not fed, water was given ad libitum
- Housing: 3 animals of one sex in one plastic breeding cage Velaz T4
- Diet (e.g. ad libitum): ST 1 BERGMAN, standard pelleted diet ad libitum (producer: Mill Kocanda, Jesenice u Prahy)
- Water (e.g. ad libitum): Drinking tap water ad libitum (quality corresponding to Regulation No. 252/2004 Czech Coll. of Law)
- Acclimation period: 6 days


ENVIRONMENTAL CONDITIONS
- Temperature (°C): 22 +/- 3
- Humidity (%):30-70
- Air changes (per hr): ca. 15
- Photoperiod (hrs dark / hrs light): 12/12


IN-LIFE DATES: From: 07 Jan 2008 To: 22 Jan 2008

Route of administration:

oral: gavage

Vehicle:

other: 0.5% methylcellulose in water

Details on oral exposure:

VEHICLE
- 0.5% methyl cellulose in water
- Justification for choice of vehicle: It is not toxic. Is it possible to prepare a homogeneous suspension of the test substance in this vehicle.
- Lot/batch no.: DT157078

MAXIMUM DOSE VOLUME APPLIED: 2000 mg/kg bw

DOSAGE PREPARATION:
Immediately before administration, the test substance was weighed, mixed in vehicle (0.5% methyl cellulose in water) and the resulting suspension was administered by gavage. The single volume of administered suspension was 1mL/100 g body weight.

CLASS METHOD
- Rationale for the selection of the starting dose: according to the methology
Testing schedule (according to EU Method B.1 tris Annex 1D):
Step No. 1: 3 females dosed 2000 mg/kg. Result: no deaths. Therefore, Step No. 2: 3 females dosed 2000 mg/kg. Result: no deaths. Thus, no further testing necessary.

Doses:

2000 mg/kg bw

No. of animals per sex per dose:

6 females (Step No.1: 3 females, Step No.2: 3 females)

Control animals:

no

Details on study design:

- Duration of observation period following administration: 14 days
- Frequency of observations and weighing: After administration, the animals were observed individually. Twice on the first day (30 minutes and 3 hours after application), twice on the second day (in the morning and in the afternoon), and daily thereafter up to the end of the study. Observations included changes in skin and fur, eyes, visible mucous membranes, behaviour, somatomotor activity, reactions to stimuli, presence of lacrimation, salivation and discharge from nostrils, function of respiratory, digestive and urogenital system.
Animals were weighed before administration, on day 8 of the study and on day 15 prior to sacrifice. Body weight gain was calculated from body weight at the start and at the end of the study.
- Necropsy of survivors performed: yes
- Other examinations performed: All test animals survived. Animals were sacrificed on day 15 by injection of a veterinary preparation T61 (1 mL iv.) and gross necropsy was carried out. Nutritious status, body surface, body foramina, thoracic, abdominal and cranial cavity were evaluated.

Sex:

female

Dose descriptor:

LD50

Effect level:

> 2 000 mg/kg bw

Based on:

test mat.

Mortality:

No mortalities occurred

Clinical signs:

other: No clinical sings of intoxication were observed.

Gross pathology:

No macroscopic changes were observed.

Interpretation of results:

other: CLP/EU GHS criteria not met, no classification required according to Regulation (EC) No 1272/2008

Conclusions:

The test substance administered orally at 2000 mg/kg bw caused no death of animals. No clinical signs of intoxication were observed. No pathologic macroscopic changes were diagnosed.
The test substance does not fufil the requirements to be classified according to DSD and CLP criteria.

Endpoint conclusion

Endpoint conclusion:

no adverse effect observed

Quality of whole database:

The selected study is the most adequate and reliable study

Acute toxicity: via inhalation route

Link to relevant study records

Reference

Endpoint:

acute toxicity: inhalation

Type of information:

migrated information: read-across from supporting substance (structural analogue or surrogate)

Adequacy of study:

key study

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

study well documented, meets generally accepted scientific principles, acceptable for assessment

Principles of method if other than guideline:

Study of pulmonary and systemic effects after inhalation exposure (4 h/day on 3 consecutive days, one dose level) in male rats.

GLP compliance:

not specified

Test type:

other: acute inhalation exposure on 3 consecutive days

Limit test:

no

Species:

rat

Strain:

Sprague-Dawley

Sex:

male

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Source: Harlan, San Diego, CA, USA.
- Age at study initiation: 8 weeks
- Weight at study initiation: 260 - 270 g
- Housing: plastic cages with TEK-Chip pelleted paper bedding
- Diet (e.g. ad libitum): Laboratory Rodent Diet 5001 (LabDiet, Brentwood, MO)
- Water (e.g. ad libitum): tap water
- Acclimation period: 5 days with acclimatisation to nose only exposure tubes.

ENVIRONMENTAL CONDITIONS
- Photoperiod (hrs dark / hrs light): 12/12

Route of administration:

inhalation: dust

Type of inhalation exposure:

nose only

Vehicle:

other: unchanged (no vehicle)

Details on inhalation exposure:

CFA was aerosolized using a belt feeder and fluidized bed system previously described by Teague et al. (2005). PM2.5 (less than 2.5 µm) size-fractionated particles were premixed with 100- to 200 -µm-diameter glass beads and loaded into a dust feed for delivery to a vibrating fluidized bed system for aerosolization of both CFA and glass beads. The aerosol subsequently passed through a cyclone separator to remove the glass beads, while the CFA remained aerosolized passing through a krypton-85 source (to reduce particle agglomeration) to the nose-only inhalation system. Particle concentration during exposure was monitored by a continuous-reading, light-scattering, dust concentration monitor and filter connected to the exposure chamber. A Grimm Series 1.108 Aerosol Spectrometer (GRIMM Aerosol Technik GmbH, Douglasville, GA) extracted a 1.2 Lpm flow, and a proprietary algorithm converted light scattering into particle mass concentration using the default calibration for occupational monitoring (PM10, PM2.5, and PM1). The particle feeder settings of the aerosolization system were adjusted as needed to achieve the target time-averaged concentration for exposure. The aerosol spectrometer was operated in the 16-channel mode to measure particle size distribution. Mass of CFA collected on the filter was used to correct the aerosol spectrometer output to obtain the actual mass concentration during exposures. The filter sample was collected at 3 L/min on a 25-mm Pallflex EMFAB TX40HI20-WW filter using an InTox filter housing connected to a diaphragm pump and a bellows-type dry gas meter.

The actual aerosol particle size generated can be approximated by a count median diameter of 0.3 µm and a geometric standard deviation of 1.4, which corresponds to a mass mode near 1 µm.

Deposition of the CFA aerosol generated was modeled using MPPD V1.0 software developed by Chemical Industry Institute of Toxicology (CIIT Center for Health Research) and Rijksinstituut voor volksgezondheid en milieu (RIVM National Institute for Public Health and the Environment) (Asgharian et al., 2002). The model inputs include measured particle size distribution, time-averaged aerosol concentration during exposure, and observed breathing rate. Based on the MPPD model, the total CFA mass deposited over the 3- day exposure was 32 µg per rat, and the regional deposition was head, 25%; tracheobronchial, 20%; and pulmonary, 55%.

Analytical verification of test atmosphere concentrations:

yes

Duration of exposure:

4 h

Remarks on duration:

4 h/day for 3 days

Concentrations:

1400 mg/m³ (= 1.4 mg/L):
The average concentration of CFA particulate matter less than 2.5 µm (PM2.5) was 1400 mg/m³, of which 600 mg/m³ was PM1.

No. of animals per sex per dose:

In total 48 animals were included into the study.
A grouping of 6 animals was reported for tissue sampling.

Control animals:

yes

Details on study design:

- Duration of observation period following administration: Animals were examined 18 and 36 h postexposure.
- Necropsy performed: yes, 18 and 36 hours after last exposure. These necropsy times were selected to measure acute responses and to approximate the 1- to 3-day lag time between increases in particle matter concentration and human effects commonly observed in epidemiology studies.
- Other examinations performed:
Bronchoalveolar lavage and biochemical assay of bronchoalveolar lavage fluid
Blood Serum and hematology parameters (red blood cell count, white blood cell count, and percentages of neutrophils, lymphocytes, monocytes, eosinophils, and basophils.)
Lung tissues for biochemistry (Cytokines and chemokines, glutathione, total antioxidant potential) and histopathology

Statistics:

All numerical data were calculated as the mean and standard deviation. Comparisons between animals exposed to CFA and filtered air were made by Student’s t-test or, where appropriate, by analysis of variance followed by Fisher’s protected least significant difference posttest.
Comparisons were considered significant if a value of p < 0.05 was observed.
Statistical analysis was performed with StatView 5.0.1 (SAS Institute, Inc., Cary, NC).

Sex:

male

Dose descriptor:

LC50

Effect level:

> 1 400 mg/m³ air

Based on:

other: test. mat. (respirable fraction of ashes)

Exp. duration:

4 h

Remarks on result:

other: Exposure duration: 4 h/day for 3 days. The average concentration of coal fly ash particulate matter less than 2.5 µm was 1400 mg/m3, of which 600 mg/m3 was less than 1 µm.

Mortality:

No mortalities occured

Other findings:

- Histopathology: Focal alveolar septal thickening and increased cellularity in selected alveoli next to terminal bronchioles. Moderate elevation in the number of alveolar macrophages was noted within the bronchiole-alveolar duct regions of the lungs both 18- and 36-h postexposure. Staining with Prussian blue iron stain demonstrated in a small fraction of alveolar macrophages the presence of iron-positive cytoplasmic inclusions, suggestive of phagocytosized CFA particles.

- Other observations:
Significant increase in neutrophils, both in the lung BALF and in the blood.
Significant increases in cytokines such as macrophage inflammatory protein-2 in BALF and IL-1b in lung tissue.
Significant increased levels of transferrin, lung tissue total antioxidant potential, plasma protein, and blood complement 4.

Interpretation of results:

other: CLP/EU GHS criteria not met, no classification required according to Regulation (EC) No 1272/2008

Conclusions:

Exposure to 1.4 mg/L of respirable coal fly ash particles derived from a plant burning bituminous coal on three consecutive days did not result in mortalities.
Therefore it can be assumed that the LC50 for male rat is greater than 1.4 mg/L of respirable coal fly ash.
The respirable fraction of Ashes (residues), cenospheres does not exceed 1.5% of the total mass (s. Particle size distribution). Accordingly, the LC50 is expected to exceed 5 mg/L of total Ashes (residues), cenospheres. Therefore, Ashes (residues), cenospheres are considered as non-toxic upon acute inhalation exposure and no classification is needed according to the DSD and CLP criteria for classification and labelling.

Endpoint conclusion

Endpoint conclusion:

no adverse effect observed

Quality of whole database:

The selected study is the most adequate and reliable study

Acute toxicity: via dermal route

Endpoint conclusion

Endpoint conclusion:

no study available

Additional information

There are no substance specific data available on the acute toxicity of ashes (residues), cenospheres.

Ashes (residues), cenospheres and ashes (residues), coal share a common production process as substances derived from coal combustion. ashes (residues), cenospheres represent a fraction of ashes (residues), coal separated by physical means. Both substances exhibit similarities in physicochemical properties and chemical composition. The main differences consist in a much lower content of water soluble matter and the particle size distribution of ashes (residues), cenospheres.

In terms of hazard assessment, studies available for ashes (residues), coal are therefore taken into account by read-across following an analogue approach, the results of these studies being considered a worst case for ashes (residues), cenospheres.

Oral

The acute toxicity of ashes (residues) after oral administration to Wistar rats was investigated according to EU Method B.1 tris under GLP conditions. Two groups of 3 female rats each were given the test material by gavage at 2000 mg/kg bw as a suspension in 0.5% methyl cellulose in water. No mortalities occurred and no clinical or pathological signs of toxicity were noted during the observation period of 14 days. The oral LD50 value for female rats was therefore considered to be greater than 2000 mg/kg bw (Rösslerová, 2008).

 

Inhalation

Male Sprague-Dawley rats were exposed to 1400 mg/m³ coal fly ash derived from a 400- MW power plant burning bituminous coal from multiple mines in the Wasatch Plateau, UT, for 4 h on three consecutive days. The average concentration of coal fly ash particulate matter less than 2.5 µm was 1400 mg/m³, out of which 600 mg/m³ was less than 1 µm. The observation period was 18 and 36 hours after the last exposure. At this time points, groups of animals were sacrificed for further examinations. Bronchoalveolar lavage, lung tissue and blood samples were analysed. No mortalities occurred. Histopathologic changes in the lung (focal alveolar septal thickening, increased cellularity, elevation in the number of alveolar macrophages with iron-positive cytoplasmic inclusions) and significant increase in neutrophils, both in the lung BALF and in the blood were noted (Smith, 2006). Based on these results, the LC50 value for male rats was assumed to be greater than 1400 mg/m³ of respirable coal fly ash particles.

The respirable fraction of ashes (residues), cenospheres typically accounts for < 1.5% of the total mass (s. Particle size distribution). Accordingly, the LC50 of total ashes (residues), cenospheres is expected to exceed 5000 mg/m³ (5 mg/L).

 

Dermal

This information is not available.

According to Section 8.5.3, Column 2 of Annex VIII to Regulation (EC) No 1907/2006, testing for acute toxicity by the dermal route is appropriate if: (1) inhalation of the substance is unlikely; and (2) skin contact in production and/or use is likely; and (3) the physicochemical and toxicological properties suggest potential for a significant rate of absorption through the skin.

Inhalation is the most relevant route of exposure for ashes (residues), cenospheres. Skin contact in production and/or use cannot be ruled out. However, based on the following considerations on physicochemical and toxicological properties, ashes (residues), cenospheres are not expected to cause death or any other systemic or local toxic effect after acute dermal exposure:

Ashes (residues), cenospheres are solid inorganic particles mostly composed of water insoluble compounds. Thus, no significant rate of absorption through the skin is expected.

The results of studies on acute oral and inhalation toxicity as well as on skin/eye irritation and skin sensitisation conducted with the analogue substance ashes (residues), coal showed no acute systemic toxicity after oral and inhalation exposure and no skin/eye irritation or skin sensitisation potential.

Therefore, based on the available data on the physicochemical properties of the ashes (residues), cenospheres as well as on toxicological data from the analogue substance ashes (residues), coal, systemic and/or local toxic effects after acute dermal exposure are unlikely to occur. Hence, testing on the acute dermal toxicity of the substance is not considered necessary and should be avoided for the sake of animal welfare.

Justification for classification or non-classification

Based on read-across following an analogue approach, the available data on the acute toxicity of ashes (residues), cenospheres is conclusive but not sufficient for classification according to GHS (CLP, 1272/2008/EC) criteria for classification and labelling.