Slags, ferrochromium-manufg.

Toxicity to reproduction

Administrative data

Endpoint:

toxicity to reproduction

Remarks:

other: 90 days inhalation toxicity study

Type of information:

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

Adequacy of study:

weight of evidence

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: see 'Remark'

Remarks:

Read-across to chromium(III) oxide. The surface of chromium metal is always covered by chromium(III) oxide and therefore the results obtained with this substance can readily be used in the assessment of chromium. Well-documented study report meeting basic scientific principles

Cross-reference

Reason / purpose for cross-reference:

reference to same study

Data source

Reference

Reference Type:

publication

Title:

Thirteen-week subchronic rat inhalation toxicity study with a recovery phase of trivalent chromium compounds, chromic oxide, and basic chromium sulfate.

Author:

Derelanko, M. J., W. E. Rinehart, et al.

Year:

1999

Bibliographic source:

Toxicol Sci.52: 278-288.

Materials and methods

Test guideline

Qualifier:

no guideline followed

Guideline:

other: equivalent or similar to OECD Guideline 413 (Subchronic Inhalation Toxicity: 90-Day)

Principles of method if other than guideline:

Nose-only exposures of chromium(III) oxide dust (4.4, 15 or 44 mg/m3) was carried out for 6 h/day 5 days/week during 13 weeks on 15 male and 15 female rats per concentration. 10 rats/sex were sacrificed at the end of the exposure and 5 rats/sex were maintained for a 13 week recovery period. An additional satellite group of 5 rats/sex/concentration was exposed to the same concentrations of chromium(III) oxide for 5 consecutive days in order to evaluate bronchoalveolar lavage parameters.
Clinical signs of toxicity were observed during the whole study period. At the study termination, standard haematology, clinical chemistry and urinalysis were conducted. Bone marrow smears were prepared, organs were weighed and tissues typically harvested in subchronic toxicity studies were preserved and evaluated microscopically. Sperm samples were evaluated.

GLP compliance:

not specified

Test material

Test material information

Constituent 1

Reference substance name:

chromium(III) oxide

IUPAC Name:

chromium(III) oxide

Details on test material:

- Name of test material (as cited in study report): Chromic oxide (CAS No. 1308-38-9)
- Molecular formula (if other than submission substance): Cr2O3
- Molecular weight (if other than submission substance): 152
- Physical state: dark green powder
- Analytical purity: >99% Cr(III) as Cr2O3
- Impurities (identity and concentrations): < 0.0002% Cr(VI)
- Composition of test material, percentage of components: >99% Cr(III) as Cr2O3
- Isomers composition: no data
- Purity test date: no data
- Lot/batch No.: no data
- Expiration date of the lot/batch: no data
- Stability under test conditions: no data
- Storage condition of test material: in a separate, unused 1 m3 chamber that was continuously purged with a low flow of dry compressed air.
- Other:

Test animals

Species:

rat

Strain:

Fischer 344

Sex:

male/female

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Source: CDF (Fischer 344)Crl BR VAF/Plus rats from Charles River Laboratories (Raleigh, NC, USA)
- Age at study initiation: 7 weeks
- Weight at study initiation: no data
- Fasting period before study: no data
- Housing: individual housing in stainless steel, suspended wire-mesh cages
- Diet (e.g. ad libitum): commercial laboratory feed Purina Certified Rodent Chow 5002 ad libitum
- Water (e.g. ad libitum): yes ad libitum
- Acclimation period: 2 weeks


ENVIRONMENTAL CONDITIONS
- Temperature (°C): 21±2 degrees Celsius
- Humidity (%): 43±11% relative humidity
- Air changes (per hr): no data
- Photoperiod (hrs dark / hrs light): 12 hrs dark / 12 hrs light


IN-LIFE DATES: From: week 13 To: week 26 (5 animals/sex/group)

Administration / exposure

Route of administration:

inhalation: dust

Type of inhalation exposure (if applicable):

nose only

Details on exposure:

GENERATION OF TEST ATMOSPHERE / CHAMBER DESCRIPTION
- Exposure apparatus: stainless steel and acrylic nose-only inhalation chambers
- Method of holding animals in test chamber: no data
- Source and rate of air: no data
- Method of conditioning air: no data
- System of generating particulates/aerosols: accomplished with a low-output dust generator, using spinning glass beads over a packed cake of test material
- Temperature, humidity, pressure in air chamber: no data
- Air flow rate: no data
- Air change rate: at least 12 chamber air changes per hour
- Method of particle size determination: made from each exposure level using a cascade impactor once per day for the first two weeks, and weekly thereafter
- Treatment of exhaust air: no data


TEST ATMOSPHERE
- Brief description of analytical method used: chamber samples were determined once per hour by standard gravimetric methods, with periodic analysis for Cr(III) and Cr(VI)
- Samples taken from breathing zone: no data on where the samples were taken from

Details on mating procedure:

No mating

Analytical verification of doses or concentrations:

yes

Details on analytical verification of doses or concentrations:

Chamber samples were determined once per hour by standard gravimetric methods, with periodic analysis for Cr(III) and Cr(VI). The mean aerosol concentrations over 13 week were 4.4±0.23, 15±1.2 and 44 ±3.7 mg/m3 for the three chromium(III) oxide groups.

Duration of treatment / exposure:

13 weeks

Frequency of treatment:

6 hours/day, 5 days/week

Details on study schedule:

No mating

Doses / concentrations

Remarks:

Doses / Concentrations:
4.4, 15 or 44 mg/m3
Basis:
nominal conc.

No. of animals per sex per dose:

15 animals/sex/dose

Control animals:

yes, sham-exposed

Details on study design:

- Dose selection rationale: The desired exposure levels were selected to be multiples of the threshold limit value (TLV) for trivalent chromium, and set at chromium equivalents of 3, 10 and 30 mg/m3.
- Rationale for animal assignment: randomly assigned to groups based on body weight.
- Rationale for selecting satellite groups: additional rats (5/sex/dose) from those described above were radomly selected
- Post-exposure recovery period in satellite groups: no (bronchoalveolar lavage analyses were performed immediately after the 5 day exposure, after which the animals were removed from the study)

Positive control:

No

Examinations

Parental animals: Observations and examinations:

CAGE SIDE OBSERVATIONS: No data


DETAILED CLINICAL OBSERVATIONS: Yes
- daily observations prior to and following each exposure for clinical signs of toxicity
- twice daily for morbidity and mortality during the recovery period and on weekends


BODY WEIGHT: Yes
- Time schedule for examinations: Recorded weekly during the exposure and recovery period


FOOD CONSUMPTION:
- Food consumption for each animal determined and mean daily diet consumption calculated as g food/kg body weight/day: No data


FOOD EFFICIENCY:
- Body weight gain in kg/food consumption in kg per unit time X 100 calculated as time-weighted averages from the consumption and body weight gain data: No data


WATER CONSUMPTION: No data


OPHTHALMOSCOPIC EXAMINATION: Yes (indirect ophthalmoscopic examination)
- Time schedule for examinations: during the acclimation period and prior to terminal necropsy
- Dose groups that were examined:


HAEMATOLOGY: Yes
- Time schedule for collection of blood: at the end of exposure
- Anaesthetic used for blood collection: No data
- Animals fasted: No data
- How many animals: 10/sex/group
- No data on which parameters were examined.


CLINICAL CHEMISTRY: Yes
- Time schedule for collection of blood: at the end of exposure
- Animals fasted: No data
- How many animals:10/sex/group
- No data on which parameters were examined.


URINALYSIS: Yes
- Time schedule for collection of urine: at the end of exposure
- Metabolism cages used for collection of urine: Yes
- Animals fasted: No data
- Determinations were performed by gross observation, microscopy and automated clinical analyzer. No data on parameters examined. Aliquots of the remaining urine from 5 animals/sex from the control gropu and the high exposure group were submitted for Beta2-microglobulin analysis.


NEUROBEHAVIOURAL EXAMINATION: No

Sperm parameters (parental animals):

sperm motility, morphology and concentration

Postmortem examinations (parental animals):

ovarian and testicular weights

Statistics:

Statistical analyses were performed on body weights, clinical pathology laboratory tests, organ weights and BALF data using one-way analysis of variance. If the result was non-significant, no further tests were performed. If the result was significant, Bartlett's test for homogeneity of variance was performed. If Bartlett's test was non-significant, Dunnett's t-test was used for pairwise comparisons. Bartlett's test was significant, the Welch t-test with Bobferroni correction was used for pairwise comparison.

Results and discussion

Results: P0 (first parental generation)

General toxicity (P0)

Clinical signs:

no effects observed

Body weight and weight changes:

no effects observed

Food consumption and compound intake (if feeding study):

no effects observed

Organ weight findings including organ / body weight ratios:

no effects observed

Histopathological findings: non-neoplastic:

effects observed, treatment-related

Other effects:

not examined

Reproductive function / performance (P0)

Reproductive function: oestrous cycle:

not examined

Reproductive function: sperm measures:

no effects observed

Reproductive performance:

not examined

Details on results (P0)

TEST SUBSTANCE INTAKE (PARENTAL ANIMALS): Not eaxamined


REPRODUCTIVE FUNCTION: ESTROUS CYCLE (PARENTAL ANIMALS) Not examined


REPRODUCTIVE FUNCTION: SPERM MEASURES (PARENTAL ANIMALS) Not examined


REPRODUCTIVE PERFORMANCE (PARENTAL ANIMALS)Not examined

CLINICAL SIGNS AND MORTALITY
No chromium(III) oxide related mortality or clinical signs of toxicity were observed at any exposure levels.

BODY WEIGHT AND WEIGHT GAIN
Mean body weights of male and female rats during exposures did not show any statistically significant differences as compared to the control groups. Mean body weights of males exposed to 44 mg/m3 chromium(III) oxide were slightly lower than controls during the recovery period, but weight gains for these animals did not differ from the control animals.

FOOD CONSUMPTION
No data

FOOD EFFICIENCY
No data

WATER CONSUMPTION
No data

OPHTHALMOSCOPIC EXAMINATION
No exposure-related effects

HAEMATOLOGY
No exposure-related effects

CLINICAL CHEMISTRY
No exposure-related effects

URINALYSIS
No exposure-related effects

NEUROBEHAVIOUR
No data

ORGAN WEIGHTS
No statistically significant changes were observed in ovarian or testicular weights.

Small, statistically significant increases in mean absolute and relative lung/trachea weights were observed among high-exposure (44 mg/m3) male rats, but not in females. This increase was explained by macroscopic and histologic changes.
Mean absolute and relative thyroid/parathyroid weights were significantly increased in the mid-exposure-group (15 mg/m3) females. Mean relative thyroid/parathyroid/body weight ratios in the 44 mg/m3 group of female rats were also significantly increased. The weight changes in these organs were very small, and their biological importance could not be determined.
At the recovery sacrifice (13 week recovery after exposures), the differences in organ weights of all the exposure groups compared with the controls were unsignificant.

GROSS PATHOLOGY
Most of the animals (both at the terminal and rcovery sacrifices) showed exposure-related macroscopic changes in the lungs and mediastinal lymph nodes. Green dicoloration was observed at all exposure levels, and increased with exposure concentration. Mediastinal lymph node enlargement was also observed in the 44 mg/m3 groups after the recovery period. In addition, a few other macroscopic observations were made, but these were considered incidental.

HISTOPATHOLOGY: NON-NEOPLASTIC
Aggregates or foci of macrophages filled with dense black pigment were randomly distributed djacent to the junctions of terminal bronchioles and alveolar ducts, and subjacent to the pleura in male and female rats exposed to all concentrations of chromium(III) oxide. Black pigment was also seen in the tracheal bifurcation, peribronchial lymphoid tissue, and within the mediastinal lymph node.
The pigment was assumed to represent the test substance and it stained black with hematoxylin and eosin stain. It corresponded to the green discoloration observed macroscopically.
Insome of the 15 and 44 mg/m3 exposure group rats (males and females), infiltration of inflammatory cells in the alveolar septa surrounding aggregates of pigmented macrophages, indicated trace to mild chronic interstitial inflammation of the lungs. Chronic interstitial inflammation and septal cell hyperplasia (Type II pneumocytes) was furthermore observed in some males exposed to 15 or 44 mg/m3.
Lymphoid hyperplasia was observed in all tets groups. No exposure-related lesions were observed in the nasal cavities of the exposed groups.
The microscopic changes observed were generally associated with the pigment and corresponded to the increased lung weight observed among males in the high-exposure group.
In animals sacrificed after the 13-week recovery period, trace to mild pigmented macrophages and black pigment were still found in the peribronchial lymphoid tissue, at about the same incidence and severity as in animals sacrificed immediately after the exposures. In all male treatment groups, and in the 15 and 44 mg/m3 female groups, trace to mild septal hyperplasia and trace to mild chronic interstitial inflammation persisted. The severity of these lesions were similar, or slightly increased, as compared with the terminal-sacrifice groups. Accumulation of black pigment in the mediastinal lymph nodes of all groups persisted. Only in some males of the 4.4 and 15 mg/m3 groups was there an increase in the incidence, indicating a pulmonary clearance via the lymphatic system.

HISTOPATHOLOGY: NEOPLASTIC (if applicable)
No data

SPERM EVALUATION: No significant effects on sperm motility, morphology or concentration were observed in any of the exposed groups.

OTHER FINDINGS
- No statistically significant differences in any of the BAL parameters where obseved when comparing exposure groups with controls. A yellow intracytoplasmic, crystalline material was present within the mononuclear cells from all exposure groups.

Effect levels (P0)

Dose descriptor:

NOAEL

Effect level:

44 mg/m³ air

Sex:

male/female

Basis for effect level:

other: NOAEL for Cr2O3 = 30 mg/m3 Cr(3+); corresponding to an inhaled dose of 6.6 mg Cr3+/kg/day

Results: F1 generation

General toxicity (F1)

Clinical signs:

not examined

Mortality / viability:

not examined

Body weight and weight changes:

not examined

Sexual maturation:

not examined

Organ weight findings including organ / body weight ratios:

not examined

Gross pathological findings:

not examined

Histopathological findings:

not examined

Overall reproductive toxicity

Reproductive effects observed:

not specified

Applicant's summary and conclusion

Conclusions:

A thirteen week rat inhalation toxicity study with chromium(III) oxide did not cause any changes in ovarian or testicular weights, or in sperm motility, morphology or concentration even at the highest dose tested. The NOAEL was 44 mg Cr2O3/m3, corresponding to 30 mg Cr(III)/m3..

Executive summary:

In a thirteen week inhalation toxicity study rats were exposed to graded doses of chromium(III) oxide for 6 hours per day, 5 days per week. No statistically significant changes were observed in ovarian or testicular weights, or in sperm motility, morphology or concentration even at the highest dose tested. According to this study, the NOAEL for reproductive effects of chromium oxide was 44 mg/m³of Cr2O3, which is equivalent to 30 mg/m³of Cr (corresponding to an inhaled dose of 6.6 mg Cr(3 +)/kg/day).