The product from the burning of a combination of carbonaceous materials.

Repeated dose toxicity: inhalation

Administrative data

Endpoint:

chronic toxicity: inhalation

Type of information:

experimental study

Adequacy of study:

weight of evidence

Study period:

No data

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: Non-GLP compliant, non-guideline experimental investigation. Study published in scientific, peer reviewed journal.

Data source

Reference

Reference Type:

publication

Title:

Studies of the chronic inhalation of coal fly ash by rats.

Author:

Raabe O G, Tyler W S, Last J A, et al.

Year:

1982

Bibliographic source:

Ann Occup Hyg. 26(1-4):189-211.

Materials and methods

Principles of method if other than guideline:

Rats were exposed to respirable (mass median aerodynamic diameter MMAD about 2 μm) aerosols of size-classified power plant fly ash at average concentrations of up to 4.2 mg m(3) for 8 h per day for up to 180 consecutive days. The aerosols were characterized with respect to both physical and chemical properties. Sampling time points were after exposure for 7, 50, 90 or 180 days. Immediately after exposure, the animals were evaluated biochemically, morphologically and with other sensitive biological tests to detect effects associated with fly ash inhalation when compared with unexposed controls.

GLP compliance:

no

Test material

Test material information

Constituent 1

Reference substance name:

Coal fly ash

EC Number:

924-417-0

IUPAC Name:

Coal fly ash

Details on test material:

Fly ash was obtained from the electrostatic precipitator hoppers of a power plant burning western USA low-sulphur, high-ash coal, and size classified to remove most particles larger than 3 um in aerodynamic diameter. The resulting fly ash source material had a volume median diameter of 1.77 um (SE 0.06) and geometric standard deviation of 1.52 (SE 0.04).

Test animals

Species:

rat

Strain:

Sprague-Dawley

Sex:

male

Details on test animals or test system and environmental conditions:

The rats were 70 days old Hilltop chronic respiratory disease (CRD) –free male rats, During exposure the rats were maintained in pairs in stainless steel wire mesh cages. Conditions in exposure chambers: temperature 21 ± 2 ºC, relative humidity 50 ± 20%.

Administration / exposure

Route of administration:

inhalation: aerosol

Type of inhalation exposure:

whole body

Vehicle:

air

Remarks on MMAD:

MMAD / GSD: 1.77 / 1.52

Details on inhalation exposure:

see Fig. 1

Analytical verification of doses or concentrations:

yes

Details on analytical verification of doses or concentrations:

Royco 225 light-scattering particle counter (Royco Instruments, Menlo Park, CA, USA). Comparison measurements were made using a Climet 208 light-scatter particle counter (Climet Instruments, Redlands, CA, USA). Particle size distribution data were collected with these instruments operated in conjunction with a multichannel pulse height analyzer.
see attached Figure

Duration of treatment / exposure:

Two series of experiments were carried out with the sampling time points after 7, 50 or 90 days of exposure and after 90 or 180 days of exposure, respectively.

Frequency of treatment:

Daily 8 h/day

Doses / concentrations

Remarks:

Doses / Concentrations:
4.2 mg/m3
Basis:

No. of animals per sex per dose:

9 - 32

Control animals:

yes

Positive control:

No

Examinations

Observations and examinations performed and frequency:

Body weight in the beginning and at the end of exposure.

Sacrifice and pathology:

Morphological evaluation of lungs: Lung volume, histopathology (light microscopy, HE staining), scanning electron microscopy (SEM), analytical electron microscopy, back-scattered electron (BSE) image for identification of individual fly ash particles.

Biochemical evaluation of lungs: DNA, RNA, protein and hydroxyproline content, mucus glycoprotein synthesis and secretion rates.

Cellular studies on lungs: alveolar macrophage and haematopoietic progenitor cell kinetics, macrophage functional assays (mobility, phagocytic indices), bone marrow granulocyte-monocyte progenitors.

Other examinations:

Lung burden measurements (aluminum) and calculation of deposited fraction in lungs.

Statistics:

Student’s t test, Mann-Whitney rank-sum test

Results and discussion

Results of examinations

Clinical signs:

no effects observed

Description (incidence and severity):

No mortality or clinical signs reported

Mortality:

no mortality observed

Description (incidence):

No mortality or clinical signs reported

Body weight and weight changes:

no effects observed

Food consumption and compound intake (if feeding study):

not specified

Food efficiency:

not specified

Water consumption and compound intake (if drinking water study):

not specified

Ophthalmological findings:

not specified

Haematological findings:

not specified

Clinical biochemistry findings:

not specified

Urinalysis findings:

not specified

Behaviour (functional findings):

not specified

Organ weight findings including organ / body weight ratios:

no effects observed

Description (incidence and severity):

No effect on lung weight, no data for other organs

Gross pathological findings:

not specified

Histopathological findings: non-neoplastic:

no effects observed

Histopathological findings: neoplastic:

no effects observed

Details on results:

Histopathology: non-neoplastic
CFA exposed animals had higher concentration of alveolar macrophages in alveolar lumens and refractile brownish pigment (presumably fly ash) was visible in these cells. Alveolar macrophages were larger than in lungs of control animals. Alveolar septal walls contained occasionally cellular aggregates consisting of some mononuclear leucocytes admixed with brownish particulate material (ash). These differences between CFA exposed and control animals had minimal impact, if any, on health status of the animals.

Lung burdens of up to 4 mg of ash were found, macrophages lavaged from lungs of exposed rats were more numerous and yielded more progenitor cell colonies in culture than from controls, tracheal mucous glycoprotein secretion was decreased at 7, 50 and 90 days of exposure and increased at 180 days and clumping of fly ash in cells in the lungs was observed. Despite of this, there were no apparent untoward health effects from inhaled fly ash, since the observed differences between exposed and control rats did not constitute an adverse response.

Effect levels

Remarks on result:

not measured/tested

Remarks:

Measured parameters defined in method description

Target system / organ toxicity

Critical effects observed:

not specified

Any other information on results incl. tables

Lung burdens of up to 4 mg of ash were found. Macrophages lavaged from lungs of exposed rats were more numerous and yielded more progenitor cell colonies in culture (at the 10% confidence level based on the Mann-Whitney rank-sum test) than from controls. Tracheal mucous glycoprotein secretion was decreased at 7, 50 and 90 days of exposure and increased at 180 days. Clumping of fly ash in cells in the lungs was observed. There were no apparent untoward health effects from inhaled fly ash, since the observed differences between exposed and control rats did not constitute an adverse response.

Applicant's summary and conclusion

Conclusions:

There were no apparent untoward health effects from inhaled fly ash, since the observed differences between exposed and control rats did not constitute an adverse response.

Executive summary:

Respiratory disease-free rats were exposed in two experiments to respirable (mass median aerodynamic diameter MMAD about 2 μm) aerosols of size-classified power plant fly ash at average concentrations of up to 4.2 mg m(3) for 8 h per day for up to 180 consecutive days. The aerosols were characterized with respect to both physical and chemical properties. Immediately after exposure, the animals were evaluated biochemically, morphologically and with other sensitive biological tests to detect effects associated with fly ash inhalation when compared with unexposed controls. Lung burdens of up to 4 mg of ash were found. Macrophages lavaged from lungs of exposed rats were more numerous and yielded more progenitor cell colonies in culture (at the 10% confidence level based on the Mann-Whitney rank-sum test) than from controls. Tracheal mucous glycoprotein secretion was decreased at 7, 50 and 90 days of exposure and increased at 180 days. Clumping of fly ash in cells in the lungs was observed. There were no apparent untoward health effects from inhaled fly ash, since the observed differences between exposed and control rats did not constitute an adverse response.