Registration Dossier

Diss Factsheets

Toxicological information

Repeated dose toxicity: inhalation

Currently viewing:

Administrative data

Endpoint:
short-term repeated dose toxicity: inhalation
Remarks:
5-day inhalation study
Type of information:
experimental study
Adequacy of study:
key study
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
test procedure in accordance with generally accepted scientific standards and described in sufficient detail

Data source

Reference
Reference Type:
publication
Title:
Use of Short-Term Assays to Evaluate the Potential Toxicity of Two New Biosoluble Glasswool Fibers
Author:
Hesterberg T. W. et al.
Year:
2002
Bibliographic source:
Inhalation Toxicology, 14:217–246

Materials and methods

Test guideline
Qualifier:
no guideline followed
Principles of method if other than guideline:
- Principle of test: Four different glass wools were evaluated for biopersistence and toxicologic effects following short-term inhalation exposure.
- Short description of test conditions: Rats were exposed nose-only to the test fiber aerosols for 5 days, 6 hours/day and maintained for up to 6 months after exposure.
- Parameters analysed / observed: inflammatory response, lung burden, lung clearance, biopersistence and mortality
GLP compliance:
not specified
Limit test:
no

Test material

Constituent 1
Reference substance name:
Man-made vitreous (silicate) fibres with random orientation with alkaline and alkali earth oxides (Na2O+K2O+CaO+MgO+BaO) content greater than 18% by weight and fulfilling one of the Nota Q conditions
EC Number:
926-099-9
Molecular formula:
Not applicable as UVCB
IUPAC Name:
Man-made vitreous (silicate) fibres with random orientation with alkaline and alkali earth oxides (Na2O+K2O+CaO+MgO+BaO) content greater than 18% by weight and fulfilling one of the Nota Q conditions
Test material form:
solid: fibres
Specific details on test material used for the study:
Fiber types used: 901F, 902, JM 901 (MMVF10.1), JM 475 (MMVF33)

The major component of each of the five test fibers is silica.

The glasswools are amorphous (i.e., vitreous). Typical of glasswools, 901F, 902, 901, and 475 are all composed of 57–66% SiO2 and 10–17% Na2O. Compared to the other glasswools, 475 glass is relatively low in CaO, MgO, and Na2O, but relatively higher in ZnO and BaO. Unlike the traditional 901 building insulation, 901F is fluorine free. Compared to the traditional 475, the newer special application fiber, 902, is lower in alumina and higher in the more rapidly dissolving components CaO and Na2O.

JM 901 (MMVF10): 57.40% SiO2, 5.17% Al2O3, 0.072% Fe22O3, 0.03% TiO2, 7.65% CaO, 4.16% MgO, 15.5% Na2O, 1.07% K2O, 0.07% SO3, 8.53% B2O3, 0.68% F2
901F: 57.95% SiO2, 5.00% Al2O3, 0.05% Fe22O3, 0.01% TiO2, 0.02% ZrO2, 0.01% Cr2O3, 6.80% CaO, 4.62% MgO, <0.01% SrO, <0.01% BaO, 16.70% Na2O, 1.08% K2O, 0.06% SO3, 8.48% B2O3
902: 66.44% SiO2, 1.91% Al2O3, 0.054% Fe22O3, 0.041% TiO2, 0.021 ZrO2, 0.002 Cr2O3, 4.63% CaO, 3.18% MgO, 0.003% SrO, 0.17% BaO, 15.95% Na2O, 0.60% K2O, 0.20% SO3, 6.72% B2O3, <0.03% F2
JM475 (MMVF33): 58.63% SiO2, 5.87% Al2O3, 0.043% Fe22O3, 0.012% TiO2, 0.034% ZrO2, 0.004% Cr2O3, 1.74% CaO, 0.24 MgO, 0.11% SrO, 4.98% BaO, 4.02% ZnO, 9.55% Na2O, 3.07% K2O, <0.05% SO3, 11.02% B2O3, 0.62% F2

Test animals

Species:
rat
Strain:
Fischer 344
Sex:
male
Details on test animals or test system and environmental conditions:
TEST ANIMALS
- Weight at study initiation: ranged 220-240 g for 901F, 173-220 g for 902 and 901 (biopersistence studies) and 147-188 g for 901F, 475, and positive control amosite (toxicology screening studies)

Administration / exposure

Route of administration:
inhalation: aerosol
Type of inhalation exposure:
nose only
Vehicle:
clean air
Mass median aerodynamic diameter (MMAD):
ca. 0.51 - ca. 0.71 µm
Details on inhalation exposure:
GENERATION OF TEST ATMOSPHERE / CHAMBER DESCRIPTION
- Exposure apparatus: Fibre aerosol generator and nose-only inhalation exposure system described in separate publication (Bernstein et al., 1995)
- System of generating particulates/aerosols: Fibre aerosol was adjusted to achieve a target concentration of fibres with lengths > 20 µm (F > 20 µm) of at least 100 fibers/cm^3
Analytical verification of doses or concentrations:
yes
Details on analytical verification of doses or concentrations:
Test aerosols were monitored for mass, fiber numbers, and bivariate fiber dimensions. Aerosol samples were collected on filters placed in animal exposure ports during testing. Fiber mass concentrations were determined in 2 aerosol samples per day for each of the 5 exposure days. Total fibers were counted in each of 5 daily samples using scanning electron microscopy. Bivariate fiber dimensions measured in 2/5 daily samples according to method outlined by WHO modified for electronic monitoring. Dimensions were measured at on-screen magnification of 7000x in a minimum of 20 fields (approx. 27 µm x 27 µm) for 400 fiber ends (representing measurements of at least 200 fibers). Percentages of fibers in each of several fiber size categories were determined in the 2 daily samples, then used to estimate numbers of fibers in each size category from the total fibers/cc counted in the samples from the remaining 3 days.
Duration of treatment / exposure:
6 hours/day
Frequency of treatment:
5 days
Doses / concentrations
Dose / conc.:
22 mg/m³ air (analytical)
Remarks:
range 12-32 mg/m³ air
=321-443 WHO fibres/cm³
=0.012-0.032 mg/L
No. of animals per sex per dose:
82-105 male rats exposed to each fibre type, 45-55 rats were exposed to filtered air (the controls)
Control animals:
yes
Details on study design:
Rats were exposed by nose-only inhalation for 5 days/6 hr/day. Post-exposure, rats were maintained for up to 6 months. At 8+ time points during the post-treatment period, 7-15 randomly selected rats/fiber exposure group and 5 control rats were euthanized and evaluated for lung fibre burden (after 1, 2, 3 days; 1 and 2 weeks; 1, 3, 6, months; 45 days (901F only).
Toxicology screening assays were evaluated in 5 rats/group after 1, 10 days, and 1 month of recovery.
Positive control:
Amosite asbestos

Examinations

Observations and examinations performed and frequency:
Rats were observed daily for mortality and for clinical signs and weighed weekly.

CAGE SIDE OBSERVATIONS: Yes
- Time schedule: daily

BODY WEIGHT: Yes
- Time schedule for examinations: weekly

CLINICAL CHEMISTRY: Yes
Sacrifice and pathology:
GROSS PATHOLOGY: No data
HISTOPATHOLOGY: Yes, thoracic histopathology
Other examinations:
Further toxicology screening assays: Pleural-cell proliferation, and pleural and bronchoalveolar lavage (PL and BAL), fluid cytology and clinical chemistry. Each parameter evaluated in 5 rats/exposure group.
Statistics:
Statistical significance of bronchoalveolar and pleural lavage was evaluated by Dunnett test based on pooled variance p < 5%/< 1%.

Results and discussion

Results of examinations

Clinical signs:
not specified
Mortality:
no mortality observed
Description (incidence):
No mention of fibre-exposed rats that died during or after the 5-day exposure due to severe health effects.
Body weight and weight changes:
not specified
Food consumption and compound intake (if feeding study):
not examined
Food efficiency:
not examined
Water consumption and compound intake (if drinking water study):
not examined
Ophthalmological findings:
not examined
Haematological findings:
not examined
Clinical biochemistry findings:
not examined
Urinalysis findings:
not examined
Behaviour (functional findings):
not examined
Immunological findings:
effects observed, treatment-related
Description (incidence and severity):
On recovery day 1, elevations in inflammatory indicators for all fibres were apparent primarily in the bronchoalveolar lavage and only slightly in the pleural lavage. By day 14, elevations in inflammatory indicators were seen in the pleural lavage but not in the bronchoalveolar lavage, for all fibres tested except 901F. On day 29-30, elevations were none/negligible for 901F, 902, and 901, but were striking in bronchoalveolar lavage and pleural lavage for 475 and amosite.
On day 1, all 5 fibres tested induced elevations in several inflammatory parameters, but by one-month post-exposure, symptoms subsided for 901F, 902, and 901, but remained for 475 and amosite.
Organ weight findings including organ / body weight ratios:
not examined
Gross pathological findings:
not specified
Neuropathological findings:
not examined
Histopathological findings: non-neoplastic:
no effects observed
Description (incidence and severity):
Exposure-related histopathological effects of glasswools 902 and 901 were only seen on 1 day after the last exposure and limited to fibre-containing microgranulomas in rats exposed to 901 and fibre-containing alveolar macrophages.
After 10 and 30 days, thoracic tissues of exposed rats did not differ from those of the control rats. (901F and 475 not tested in this study). The fibres were associated with initial minimal to slight macrophage aggregation and microgranulomas on recovery day 1.
Wagner scores for 901 and 902 glasswools were normal by 30 days of recovery. Some inflammatory symptoms were associated with 475 and amosite after 30 days; average Wagner scores for animals exposed to 475 and amosite increased slightly.

For individual results see Table 1 in box "Any other information on results incl. tables".
Histopathological findings: neoplastic:
not examined
Other effects:
effects observed, treatment-related
Description (incidence and severity):
Lung burdens: Average lung fibre burdence in the biopersistence studies were 7-12 for WHO fibres and 1.0-1.6 for F >20 µm initial amosite lung burdens tended to be higher than those of the glasswools, especially for total fibres; in millions of total fibres per lung, lung burdens were 10–18 for the glasswools and 23 for amosite.
Details on results:
A lack of lethality or severe health effects after short-term exposure to any of the tested fibres was observed.

Effect levels

Remarks on result:
not determinable because of methodological limitations
Remarks:
Only one concentration tested

Target system / organ toxicity

Critical effects observed:
not specified

Any other information on results incl. tables

Table 1: Lung histopathology in rats exposed to glasswools or amosite asbestos

Wagner grade: 1 = normal, 2 = macrophage aggregation, 3 = cellularity; 4 = minimal fibrosis, 5 -7 = increasing fibrosis

     Pathology scores         
Day after exposure ended  Fibre  Macrophage aggregation  Microgranulomas  Bronchiolization  Wagner grade
 Day 1  Air  0  0  0  1
   902  1.2  1.0  0  1
   901  1.0  0  0  1
   901F  1.6  0.8  0  2
 Day 14  Air  0  0  0  1
   902  0  0  0  1
   901  0  0  0  1
   901F  0  0.4  0  1.8
   475  0.2  1.8  0  2
   Amosite  1.4  2.0  0  2
 Day 29 -30  Air  0  0  0  1
   902  0  0  0  1
   901  0  0  0  1
   901F  0  0  0  1
   475  0.6  1.4  0.4  2.2
   Amosite  0  2.5  1.0  2.6

Applicant's summary and conclusion

Conclusions:
No mention of fibre-exposed rats that died during or after the 5-day exposure due to severe health effects. The main effect reported after exposure was increased inflammatory responses in the form of fibre-containing microgranulomas in JM 901-esposed rats and fibre-containing alveolar macrophages in JM 901 or 902-exposed rats seen 1 day after exposure ended. The effects were no longer observed after 10 and 30 days of recovery without fibre exposure (i.e. the effects were reversible).
Executive summary:

In a short-term inhalation study, male Fischer 344 rats (82 to 105 per dose) were exposed to four glass wools (JM 901/MMVF10.1, JM 901F, JM 902, JM 475) and amosite asbestos (positive control) for 5 days, 6 hours/day. The concentration of the fibres ranged between 12 to 32 mg/m³ with the mean concentration of 22 mg/m3. This study demonstrated the lack of lethality or severe health effects after short-term exposure to any of the glass wool fibres. The main effect reported after exposure to the glass wool fibres was increased inflammatory responses in the form of fibre-containing microgranulomas in JM 901-esposed rats and fibre-containing alveolar macrophages in JM 901 or 902-exposed rats seen 1 day after exposure ended. The effects were no longer observed after 10 and 30 days of recovery without fibre exposure (i.e. the effects were reversible).