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EC number: 266-007-8 | CAS number: 65996-74-9 The oxidized surface of steel produced during reheating, conditioning, hot rolling, and hot forming operations. This substance is usually removed by process waters used for descaling, roll and material cooling, and other purposes. It is subsequently recovered by gravity separation techniques. Composed primarily of high-purity iron oxides. May contain varying amounts of other oxides, elements, and trace compounds.
- Life Cycle description
- Uses advised against
- Endpoint summary
- Appearance / physical state / colour
- Melting point / freezing point
- Boiling point
- Density
- Particle size distribution (Granulometry)
- Vapour pressure
- Partition coefficient
- Water solubility
- Solubility in organic solvents / fat solubility
- Surface tension
- Flash point
- Auto flammability
- Flammability
- Explosiveness
- Oxidising properties
- Oxidation reduction potential
- Stability in organic solvents and identity of relevant degradation products
- Storage stability and reactivity towards container material
- Stability: thermal, sunlight, metals
- pH
- Dissociation constant
- Viscosity
- Additional physico-chemical information
- Additional physico-chemical properties of nanomaterials
- Nanomaterial agglomeration / aggregation
- Nanomaterial crystalline phase
- Nanomaterial crystallite and grain size
- Nanomaterial aspect ratio / shape
- Nanomaterial specific surface area
- Nanomaterial Zeta potential
- Nanomaterial surface chemistry
- Nanomaterial dustiness
- Nanomaterial porosity
- Nanomaterial pour density
- Nanomaterial photocatalytic activity
- Nanomaterial radical formation potential
- Nanomaterial catalytic activity
- Endpoint summary
- Stability
- Biodegradation
- Bioaccumulation
- Transport and distribution
- Environmental data
- Additional information on environmental fate and behaviour
- Ecotoxicological Summary
- Aquatic toxicity
- Endpoint summary
- Short-term toxicity to fish
- Long-term toxicity to fish
- Short-term toxicity to aquatic invertebrates
- Long-term toxicity to aquatic invertebrates
- Toxicity to aquatic algae and cyanobacteria
- Toxicity to aquatic plants other than algae
- Toxicity to microorganisms
- Endocrine disrupter testing in aquatic vertebrates – in vivo
- Toxicity to other aquatic organisms
- Sediment toxicity
- Terrestrial toxicity
- Biological effects monitoring
- Biotransformation and kinetics
- Additional ecotoxological information
- Toxicological Summary
- Toxicokinetics, metabolism and distribution
- Acute Toxicity
- Irritation / corrosion
- Sensitisation
- Repeated dose toxicity
- Genetic toxicity
- Carcinogenicity
- Toxicity to reproduction
- Specific investigations
- Exposure related observations in humans
- Toxic effects on livestock and pets
- Additional toxicological data
Repeated dose toxicity: inhalation
Administrative data
- Endpoint:
- sub-chronic toxicity: inhalation
- Type of information:
- experimental study
- Adequacy of study:
- weight of evidence
- Reliability:
- 1 (reliable without restriction)
- Rationale for reliability incl. deficiencies:
- guideline study
Data source
Referenceopen allclose all
- Reference Type:
- study report
- Title:
- Unnamed
- Year:
- 2 006
- Report date:
- 2006
- Reference Type:
- publication
- Title:
- Subchronic inhalation toxicity of iron oxide (magnetite, Fe3O4) in rats: pulmonary toxicity is determined by the particle kinetics typical of poorly soluble particles
- Author:
- Pauluhn, J.
- Year:
- 2 011
- Bibliographic source:
- J. Appl. Toxicol. 2012; 32:488-504
Materials and methods
Test guideline
- Qualifier:
- according to guideline
- Guideline:
- OECD Guideline 413 (90-Day (Subchronic) Inhalation Toxicity Study
- Version / remarks:
- 2008-09-30
- Principles of method if other than guideline:
- The 13-week subchronic inhalation study was conducted also according to OECD guidance 39 (2009).
- GLP compliance:
- yes
- Limit test:
- no
Test material
- Reference substance name:
- Triiron tetraoxide
- EC Number:
- 215-277-5
- EC Name:
- Triiron tetraoxide
- Cas Number:
- 1317-61-9
- Molecular formula:
- Fe3O4
- IUPAC Name:
- Iron oxide
- Test material form:
- solid: particulate/powder
- Details on test material:
- - Name of test material: magnetite, Ferroxide® black 88P
- Average pore diameter of particles: 981 nm
- specific N2-BET surface area: approximately 10 m2/g
- Porosity: 82 %
- Penetrated Hg-pore volume: 1029 mm3/g
- Surface area of particles (based on porosimetry): 11.4 m2/g
- Bulk and apparent density were 0.8 and 4.56 g/cm3, respectively
Constituent 1
- Specific details on test material used for the study:
- SOURCE OF TEST MATERIAL
- Source of test material: Rockwood, Torino, Italia
Test animals
- Species:
- rat
- Strain:
- Wistar
- Remarks:
- HsdCpb:WU
- Sex:
- male/female
- Details on test animals or test system and environmental conditions:
- TEST ANIMALS
- Source: Winkelmann, Borchen, Germany
- Age at study initiation: 2 months
- Weight at study initiation: approx. 228 g (males); 156 g (females)
- Housing: singly housed in polycarbonate cages, containing low‐dust wood shavings as beddingmaterial.
- Diet (ad libitum): standard fixed‐formula diet (KLIBA 3883 pellets maintenance diet for rats and mice (supplier: PROVIMI KLIBA SA, 4303 Kaiseraugst, Switzerland))
- Water (ad libitum): tap water
- Acclimation period: approximately 2 weeks
ENVIRONMENTAL CONDITIONS
- Temperature (°C): 22
- Humidity (%): 40 - 60
- Air changes (per hr):
- Photoperiod (hrs dark / hrs light): 12 / 12
Administration / exposure
- Route of administration:
- inhalation: aerosol
- Type of inhalation exposure:
- nose only
- Vehicle:
- air
- Remarks:
- conditioned dry air
- Mass median aerodynamic diameter (MMAD):
- 1.3 µm
- Geometric standard deviation (GSD):
- 1.2
- Details on inhalation exposure:
- GENERATION OF TEST ATMOSPHERE / CHAMBER DESCRIPTION
The test atmposphere was forced through openings in the inner concentric cylinder of the chamber, towards the rats'breathing zone (direct-flow). The stability of the test atmosphere was monitored continously using an aerosol real-time device (vide infra)
- System of generating particulates/aerosols: WRIGHT DUST FEEDER system (BGI Inc., Waltham, M A, USA)
- Temperature, humidity, pressure in air chamber: controlled and measured continously
- Air flow rate: monitored and controlled continously by calibrated mass flow meters (Hastings HFCC Mass Flow Controllers, Teledyne Hastings-Raydist, Hampton, VA, USA). TYLAN FC-280 S mass flow controller was used for the analytical sampling.
- Method of particle size determination: samples (from breathing zone) analyzed using a BERNERTYPE AERAS low pressure critical orifice cascade impactor. A cyclone was used to prevent particles larger than 10 μm to enter in the inhalation chamber.
- Treatment of exhaust air: purification via aerosol and HEPA filters.
TEST ATMOSPHERE
- Brief description of analytical method used: gravimetric analysis
- Samples taken from breathing zone: yes, 3 samples/exposure day/ chamber - Analytical verification of doses or concentrations:
- yes
- Details on analytical verification of doses or concentrations:
- The actual concentrations were determined by gravimetric analysis (filter: Glass-fiber-filter, Sartotius, Gottingen, Germany). Filters were evaluated by gravimetric analysis (balance: Mettler AE 100).
- Duration of treatment / exposure:
- 10 animals/sex/group were exposed for 13 consecutive weeks; 10 animal/sex/group were exposed for 13 - 14 consecutive weeks
- Frequency of treatment:
- 6 hours/, 5 days/week
Doses / concentrationsopen allclose all
- Dose / conc.:
- 4.7 mg/m³ air (analytical)
- Remarks:
- ± 0.6; 5 mg/m3 (nominal)
- Dose / conc.:
- 16.6 mg/m³ air (analytical)
- Remarks:
- ± 3; 15 mg/m3 (nominal)
- Dose / conc.:
- 52.1 mg/m³ air (analytical)
- Remarks:
- ± 6.4; 50 mg/m3 (nominal)
- No. of animals per sex per dose:
- 20 (10 for haematology, clinical pathology, urinalysis, determination of organ weights and histopathology; 10 for analyses in BAL and iron organ burdens)
- Control animals:
- yes, concurrent vehicle
- Details on study design:
- - Dose selection rationale: two dose-range finding studies were performed with different Fe oxides (2 weeks) and with Fe3O4 (4 weeks).
** The examined endpoints for the 10 rats/group exposed for 13 weeks were according to the OECD 413, while the remaining 10 rats/group were necropsied 1 -2 weeks later (exposure continued) and were subjected to BAL and analysis of Fe body burden of selected organs. - Positive control:
- No
Examinations
- Observations and examinations performed and frequency:
- CAGE SIDE OBSERVATIONS: Yes
- Time schedule: daily; before and after exposure
DETAILED CLINICAL OBSERVATIONS: No
BODY WEIGHT: Yes
- Time schedule for examinations: twice weekly on Mondays and Fridays during the exposure period and once weekly during the post exposure period.
FOOD CONSUMPTION:
- Food consumption for each animal determined and mean daily diet consumption calculated as g food/day: Yes
- Compound intake calculated as time-weighted averages from the consumption and body weight gain data: No
WATER CONSUMPTION: Yes
- Time schedule for examinations: once per week
OPHTHALMOSCOPIC EXAMINATION: Yes
- Time schedule for examinations: prior to start and at the end of the exposure period
- Dose groups that were examined: 10 rats/sex/group
HAEMATOLOGY: Yes
- Time schedule for collection of blood: at the end of the 13‐week study period
- Anaesthetic used for blood collection: Not specified
- Animals fasted: Not specified
- How many animals: 10 rats/sex/group
- Parameters examined: erythrocytes (ERY), hematocrit (HCT); hemoglobin (Hb); Hepato Quick (HQUICK); leukocytes (LEUKO); mean corpuscular Hb (MCH); mean corpuscular Hb concentration (MCHC); mean corpuscular volume (MCV); thrombocytes/platelets (THRO).
CLINICAL CHEMISTRY: Yes / No / Not specified
- Time schedule for collection of blood:
- Animals fasted: Yes / No / Not specified
- How many animals:
- Parameters checked in table [No.?] were examined.
URINALYSIS: Yes
- Time schedule for collection of urine: at the end of the 13‐week study period, uirne was collected over night.
- Metabolism cages used for collection of urine: Yes / No / Not specified
- Animals fasted: Yes / No / Not specified
- How many animals: 10 rats/sex/group
- Parameters examined:
NEUROBEHAVIOURAL EXAMINATION: No
IMMUNOLOGY: No
BRONCHOALVEOLAR LAVAGE FLUID (BALF): Yes
- Time schedule for analysis: at the end of the 13–14 week exposure period
- Dose groups that were examined: control and all dose groups
- Number of animals: 10 rats/group/sex
- Parameters examined: TCC, total cell count in BAL; MCD, mean cellular
diameter; MCV, mean cellular volume; LDH, lactate dehydrogenase; AP, alkaline phosphatase; ACPH, acid phosphatase; PROT, protein; PLIPf, phospholipids in BALF; AM, alveolar macrophages; PMN, polymorphonuclear cells; LYM, lymphocytes; EOS, eosinophils; foamy, foamy; NC, cells not classifiable; NAG, β‐N‐acetyl‐glucosaminidase.
LUNG BURDEN: Yes
- Time schedule for analysis: at the end of the 13 week exposure period
- Dose groups that were examined:
- Number of animals: 10 rats/sex/group
- Parameters examined: Fe3O4 levels in LALN - Sacrifice and pathology:
- GROSS PATHOLOGY
clinical pathology was performed at the end of the 13‐week study period using 10 rats per group per sex. Rats were necropsied (surviving rats were sacrificed) and were given a gross-pathological examination. The general physical condition, body orifices, external and internal organs and tissues were examined.
ORGAN WEIGHT:
At the terminal sacrifice, organ weights were determined (adrenal glands, brain, heart, kidneys, liver, lung, lung-associated lymph nodes (LALN), ovaries, spleen, testes, thymus) and organs were persevered for histopathology.
HISTOPATHOLOGY
Examinations were performed to all the organs mentioned above and to a list of tissues. The histopathological evaluations focused on the entire respiratory tract (nasal passages, trachea, lung, lung-associated lymph nodes); it also included all extrapulmonary organs (OECD Guideline 413). - Statistics:
- Depending on variates: Dunnet test, Adjusted Welch test, Kruskal-Wallis test followed by Adjusted U tests, Analysis of Variance (ANOVAbctic). A detailed description is provided.
Results and discussion
Results of examinations
- Clinical signs:
- effects observed, treatment-related
- Mortality:
- no mortality observed
- Body weight and weight changes:
- no effects observed
- Food consumption and compound intake (if feeding study):
- no effects observed
- Food efficiency:
- not examined
- Water consumption and compound intake (if drinking water study):
- no effects observed
- Ophthalmological findings:
- no effects observed
- Haematological findings:
- effects observed, treatment-related
- Description (incidence and severity):
- - 50 mg/m3: significantly increased neutrophil counts in peripheral blood cytodifferentials occurred in all iron oxide male groups and in female rats.
- Clinical biochemistry findings:
- not examined
- Endocrine findings:
- not examined
- Urinalysis findings:
- no effects observed
- Behaviour (functional findings):
- not examined
- Immunological findings:
- not examined
- Organ weight findings including organ / body weight ratios:
- effects observed, treatment-related
- Description (incidence and severity):
- - 15 and 50 mg/m3: significantly increased lung and LALN weights were observed in both sexes.
- Gross pathological findings:
- no effects observed
- Neuropathological findings:
- no effects observed
- Histopathological findings: non-neoplastic:
- effects observed, treatment-related
- Description (incidence and severity):
- - 5, 15 and 50 mg/m3: black discolorations of lungs and lung associated lymph nodes were observed macroscopically in almost all Fe3O4 exposure groups, with increasing grading. Black macrophages were seen in the lungs of all exposed groups and they increased in a dose-dependent manner. In all males and females exposed to the upper two concentrations and in the majority of exposed to the lowest concentration, bronchiolar-alveolar hypercellularity and black macrophages in BAL were detected.
- 15 and 50 mg/m3: examinations revealed focal pigmented macrophages in the trachea of many substance-exposed rats. The paracortical area of LALNs appeared stastistically significantly enlarged in all the males and almost all females exposed to the the upper two concentrations.
- 50 mg/m3: in the nasal cavity, eosinophilic epithelial globules occured in both males and females exposed at the highest two concentrations. Epithelial metaplasia was observed in some of the male rats and focal inflammatory infiltrates occured in some females. Serius-red staining of the lung resulted in the observation of increased collagenous fibers in all animals of both sexes at the highest concentration. - Histopathological findings: neoplastic:
- no effects observed
- Other effects:
- effects observed, treatment-related
- Description (incidence and severity):
- BRONCHOALVEOLAR LAVAGE FLUID:
- 5, 15 and 50 mg/m3: alveolar macrophages appeared significantly increased already at the dose of 5 mg/m3. A concentration-dependent increase was observed in polymorphonuclear cells (PMNs) at 5 mg/m3 and above. Slight increases of phospholipids in BAL fluid were detected in animals exposed to the highest concentration, while BAL protein levels increased already at 5 mg/m3, albeit slightly.
- 15 and 50 mg/m3: A remarkable increase of total cell count (TCC) occured in animals exposed to the upper two concentrations. The LDH measurements revealed signs of cytotoxicity at 15 mg/m3 and above. Beta-N-acetyl-glucosaminidase activity appeared elevated in both sexes; this was the case for acid phosphatase in female rats.
The results of the BAL analysis are summarized in Table 11 (see attachment).
LUNG BURDEN:
- 5, 15 and 50 mg/m3: iron oxide translocation was minimally increased above the background iron levels of this organ at low-dose (approx. 30 times below the LALN iron‐burden observed at mid-dose). However, the respective increase at mid- and high-dose was proportional to the exposure concentration. Lung iron levels were determined but could not be interpreted due to a protocol error (iron analysis in lavaged lungs). - Details on results:
- MORTALITY:
- The exposures were tolerated without mortality.
BODY WEIGHT AND WEIGHT CHANGES:
- The exposures were tolerated without concentration‐dependent significant changes in body weights.
FOOD CONSUMPTION:
The exposures were tolerated without concentration‐dependent significant changes in food consumption.
WATER CONSUMPTION:
The exposures were tolerated without concentration‐dependent significant changes water consumption.
OPHTHALMOLOGICAL FINDINGS:
- No abnormality in ophthalmology (performed prior to the start and towards the end of study) was observed.
HAEMATOLOGICAL FINDINGS:
- 5 and 15 mg/m3: PMN counts were still within the range of historical control data.
URINALIS FINDINGS:
- Urinalysis did not demonstrate differences across groups (data not shown).
ORGAN WEIGHT FINDINGS INCLUDING ORGAN / BODY WEIGHT RATIOS:
- Absolute and relative (vs body weights) organ weights were confounded by the inconsistently higher body weight gains of the male control rats. Toxicologically conclusive changes in the remaining organ weights were not observed when using the organ‐to‐brain weight ratios.
GROSS PATHOLOGICAL FINDINGS:
- General clinical pathology, including hemostasis did not demonstrate differences across groups (data not shown).
HISTOPATHOLOGICAL FINDINGS:
- Adverse extrapulmonary effects of Fe3O4 were not observed at any concentration.
- 5, 15 and 50 mg/m3: diffuse tubular atrophy/degeneration was detected in 1 high-dose rat and in 3 rats from each of the other concentration groups. As stated by the authors, corresponding to these lesions, spermatic debris occured in the epididymides. These findings are not related to the concentration of the substance and in several animals they occured unilaterally. Therefore, they are not exposure related.
- Testes: (Multi)-focal tubular atrophy and degeneration was seen in all groups including the controls.
Effect levels
- Dose descriptor:
- NOAEC
- Effect level:
- 4.7 mg/m³ air (analytical)
- Based on:
- test mat.
- Sex:
- male/female
- Basis for effect level:
- immunology
- organ weights and organ / body weight ratios
Target system / organ toxicity
- Critical effects observed:
- not specified
Any other information on results incl. tables
LUNG BURDEN - HALF-TIME:
The time- and particle volume-dependence of lung burdens of Fe3O4 in rats exposed for 13 weeks for 6 h/day on 5 day/week in the present study were modeled. The following half-time for each concentrations were calculated: 5 mg/m3: 94 days; 15 mg/m3: 177 days; 50 mg/m3: 392 days. According to the athor, the lung overload treshold was reached after inhalation from a concentration of 15 mg/m3. The exposure concentrations selected for the 13 week study were modeled to attain the overload threshold (NOAEL) at 5 mg/m3 with overload‐dependent pulmonary inflammation at 15 and 50 mg/m3. The overload‐dependent delay in clearance was expected to be in the range of t1/2≈1 year at 50 mg/m3.
BRONCHOALVEOLAR LAVAGE FLUID:
Many cells in the BAL fluid could not be clearly differentiated due to extreme loading and were classified as 'non-classifiable cells'. However, most non-classifiable cells were assumed to be alveolar macrophages by the authors of the study report.
Applicant's summary and conclusion
- Conclusions:
- In the subchronic inhalation toxicity study by Pauluhn (2006a), iron(II,III) oxide (Fe3O4) aerosols were administered to Wistar rats (20 male and 20 female per group) by the dynamic directed-flow nose-only technique; actual mean concentrations were 0, 4.7 ±0.6, 16.6 ±3 and 52.1 ±6.4 mg/m3 air; the animals were exposed for 6 h/day, 5 days/week over a period of 13 weeks. Ten rats/group were necropsied 1 - 2 weeks later (exposure continued). Particles had a MMAD of 1.3 µm and GSD ~2.
In a subchronic inhalation study, 20 male and female Wistar rats were exposed to aerosolized Fe3O4 at concentrations of 4.7, 16.6 and 52.1 mg/m3 (Pauluhn (2006a); Pauluhn (2011)) by the dynamic directed-flow nose-only technique. The animals were exposed for 6 h/day, 5 days/week over a period of 13 weeks. Ten rats/group were necropsied 1 - 2 weeks later (exposure continued). Particles had a MMAD of 1.3 µm and GSD ~2. Clinical signs were recorded daily before and after exposure. Body weights were recorded twice weekly, and food and water consumption were determined once a week. Also, an ophthalmology was performed prior to start and the end of the exposure period. At sacrifice, inflammatory endpoints were determined in bronchoalveolar lavage (BAL). Rats were subjected to gross pathological examination and histopathology (adrenal glands, brain, heart, kidneys, liver, lung, LALNs, ovaries, spleen, testes, thymus).
The exposure was not associated with any specific clinical signs and consistent changes in body weights. Haematology, clinical pathology and urinalysis were unobtrusive.
The NOAEC was 4.7 mg/m3, based on the findings from BAL analysis (increased PMNs, protein levels) and histopathology. Mild and borderline changes were considered to be associated with the exposure to poorly soluble particles rather than specific toxicity of the tested particles. The effects found at higher concentrations appear to be consistent with a particle-overload related inflammatory response.
The results of this inhalation RDT study in Wistar rats can generally be regarded as reliable without restrictions, since the study was conducted according to OECD guideline 412 (2008) and under GLP.
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