Lithium potassium titanium oxide

Repeated dose toxicity: inhalation

Administrative data

Endpoint:

short-term repeated dose toxicity: inhalation

Type of information:

experimental study

Adequacy of study:

supporting study

Study period:

February 23, 2004 - March 05, 2004

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

comparable to guideline study with acceptable restrictions

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2004

Report date:

2004

Materials and methods

Test guideline

Qualifier:

equivalent or similar to guideline

Guideline:

OECD Guideline 412 (Subacute Inhalation Toxicity: 28-Day Study)

Version / remarks:

1981

Deviations:

yes

Remarks:

Exposure period 2-weeks (is part of the guideline), males only, organs weighed (lung and brain only) and histopathological examination (respiratory tract tissues only)

GLP compliance:

yes

Limit test:

no

Test material

Test material information

Constituent 1

Reference substance name:

Lithium Potassium Titanium Oxide

EC Number:

445-620-6

Cas Number:

39318-30-4

Molecular formula:

Hill Empirical formula: K(0.5-0.7) Li(0.27) Ti(1.73) O(3.8-3.95) CAS Empirical formula: K(0.5-0.7) Li(0.27) Ti(1.73) O(3.8-3.95)

IUPAC Name:

Lithium Potassium Titanium Oxide

Test material form:

solid: particulate/powder

Remarks:

White powder

Details on test material:

Name as indicated in report: Terracess L

Test animals

Species:

rat

Strain:

other: Crl:CD(SD)

Sex:

male

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Source: Charles River Laboratories, Inc., Raleigh, North Carolina.
- Age at study initiation: approx. 8 weeks
- Weight at study initiation: males, 206-269 grams.
- Housing: Except during exposure, animals were housed singly in stainless steel, wire-mesh cages suspended above cage boards.
- Diet: Except during exposures, PMI® Nutrition International, LLC Certified Rodent LabDiet® 5002 was available ad libitum. During the urine collection period, animals were fasted overnight.
- Water: ad libitum
- Acclimation period: 6 days

ENVIRONMENTAL CONDITIONS
- Temperature (°C): 18-26
- Humidity (%): 30-70
- Photoperiod (hrs dark / hrs light): 12-hour light/dark cycle

Administration / exposure

Route of administration:

inhalation: aerosol

Type of inhalation exposure:

whole body

Remarks on MMAD:

MMAD / GSD: A sample to determine particle size distribution (mass median aerodynamic diameter and percent particles less than 1, 3, and 10 μm diameter) was taken once per week per test level over the course of the daily exposure period. The MMAD of the aerosols ranged from 2.9 to 3.3 μm.

Details on inhalation exposure:

GENERATION OF TEST ATMOSPHERE / CHAMBER DESCRIPTION
Chamber atmospheres were generated by suspension of the substance in air with a FLuid Energy Processing model 00 Jet-o-Mizer. The test substance was metered into the jetmill with a Schenck Accurate model 102M bin feeder. High-pressure air, metered into the jet-o-mizer by a distribution manifold, carried the resulting atmosphere into the exposure chamber. Dilution air, delivered with a rotometer, was added to the chambers when needed to achieve the desired concentration. Chamber concentrations of test substance were also controlled by varying the feed rate or airflow to the atmosphere generator. Air was supplied to the control chamber using a rotometer.
All exposure chambers were constructed of stainless steel and glass (NYU style) with a nominal internal volume of 350 L. A baffle inside the chamber promoted uniform chamber distribution of the test atmosphere. During exposure, animals were individually placed in stainless steel wire mesh cages and exposed, whole-body, inside the exposure chamber. The chamber volume was chosen so that the total body volume of the test animals did not exceed 5% of the chamber volume.

- Temperature, humidity in air chamber: Chamber temperature was targeted at 22 ± 3°C. Relative humidity wat targeted at 50 ± 20%.
- Air flow rate: mean airflow ranged from 50 to 57 L/min
- Air change rate: 9 tot 10 changes per hour
- Method of particle size determination: Sierra series 210 cyclone preseparator/cascade impactor and Sierra series 110 constant flow air sampler.

Analytical verification of doses or concentrations:

yes

Details on analytical verification of doses or concentrations:

During each exposure, the atmospheric concentration of the test substance was determined by gravimetric analysis at approximately hourly intervals in the test chambers. Known volumes of chamber atmosphere were drawn from the sampling port through a 25 mm filter cassette containing a pre-weighed glass fiber (Type A/E) filter. The filters were weighed on a Cahn model C-33 Microbalance®. The atmospheric concentration of the test substance was calculated from the difference between the pre- and post-sampling filter weights divided by the volume of chamber atmosphere sampled. The control chamber was not monitored for the test substance. A Microdust Pro dust analyzer was used during the study as an aid in control of atmospheric dust concentrations; however, these readings were not recorded.

Duration of treatment / exposure:

2-week, 9 exposures

Frequency of treatment:

6 h/d, 5 d/w (holidays excluded)

Doses / concentrations

Doses / concentrations 1

Dose / conc.:

4.8 mg/m³ air (analytical)

Doses / concentrations 2

Dose / conc.:

26 mg/m³ air (analytical)

Doses / concentrations 3

Dose / conc.:

100 mg/m³ air (analytical)

No. of animals per sex per dose:

10 males

Control animals:

other: air only

Details on study design:

- Dose selection rationale: Based on an acute inhalation toxicity study (no mortality seen in male and female rats after 4-hour exposure to 5300 mg/m3 of test substance dust), the concentrations were chosen.
- Rationale for animal assignment: Male rats were selected for use on study based on adequate body weight gain and freedom from any clinical signs of disease or injury. They were distributed by computerized, stratified randomization into study groups, so that there were no statistically significant differences among group body weight means. At the start of the study, the weight variation of selected rats did not exceed ± 20% of the mean weight.

Positive control:

Not relevant.

Examinations

Observations and examinations performed and frequency:

CAGE SIDE OBSERVATIONS: Yes
- Time schedule: daily

DETAILED CLINICAL OBSERVATIONS: Yes
- Time schedule: At every weighing and during/after exposure.
During the daily exposures, the response to an alerting stimulus was determined for the rats as a group within the exposure chamber at the beginning of each exposure, 3 times during exposure, and at the end of each exposure. Immediately following every exposure and at every weighing, each rat was individually handled and examined for abnormal behavior and appearance.

BODY WEIGHT: Yes
- Time schedule for examinations: 3 times per week

FOOD CONSUMPTION : No

WATER CONSUMPTION: No

OPHTHALMOSCOPIC EXAMINATION: No

HAEMATOLOGY: Yes
- Time schedule for collection of blood: At sacrifice
- Anaesthetic used for blood collection: Yes carbon dioxide anesthesia
- Animals fasted: Yes, overnight (at least 15 hours)
- How many animals: All
- Parameters: red blood cell count, hemoglobin, hematocrit, mean corpuscular volume, mean corpuscular hemoglobin, mean corpuscular hemoglobin concentration, red blood cell distribution width, absolute reticulocyte count, platelet count, white blood cell count, differential white blood cell count, microscopic blood smear examination, prothrombin time, activated partial thromboplastin time.

CLINICAL CHEMISTRY: Yes
- Time schedule for collection of blood: Not specified
- Animals fasted: Yes, overnight (at least 15 hours)
- How many animals: All
- Parameters: aspartate aminotransferase, alanine aminotransferase, sorbitol dehydrogenase, alkaline phosphatase, total bilirubin, urea nitrogen, creatinine, cholesterol, triglycerides, glucose, total protein, albumin, globulin, calcium, inorganic phosphorus, sodium, potassium, chloride.

URINALYSIS: Yes
- Time schedule for collection of urine: Overnight (at least 15 hours)
- Metabolism cages used for collection of urine: Yes
- Animals fasted: Yes
- Parameters: quality, color, clarity, volume, osmolality, pH, glucose, ketone, bilirubin, blood, urobilinogen, protein, microscopic urine sediment examination.

NEUROBEHAVIOURAL EXAMINATION: No

IMMUNOLOGY: No

Sacrifice and pathology:

On the day following the last exposure, blood and urine samples were collected for clinical pathology analyses, and the rats were sacrificed for anatomic pathology examination. These included gross observations, organ weights (lung and brain) and histopathology (respiratory tract tissues).

Statistics:

Significance was judged at p < 0.05.
Method of statistical analysis:
Exposure concentration data, environmental data: descriptive statistics (e.g., mean, standard deviation).
Body weight, body weight gain, clinical pathology, organ weight: Levene’s test for homogeneity and Shapiro-Wilk test for normality in the preliminary test. One-way analysis of variance followed with Dunnett's test if preliminary test is not significant. Kruskal-Wallis test followed with Dunn's test if preliminary test is significant.
Incidence of clinical observations: Cochran-Armitage test for trend.

Results and discussion

Results of examinations

Clinical signs:

no effects observed

Mortality:

no mortality observed

Body weight and weight changes:

no effects observed

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:

effects observed, treatment-related

Description (incidence and severity):

The incidence of trace polychromasia was minimally higher in rats exposed to 25 or 100 mg/m3, compared to controls. However, there were no treatment-related changes in reticulocyte counts. Therefore the increased numberd of observations of trace polychromasia did not indicate a change in the maturity of the peripheral blood red cells, and was due to the lower sampling size of the microscopic examination. Therefore, the increased incidence in trace polychromasia was not considered to be treatment-related.

Activated partial thromboplastin time was decreased (not statistically significant) in male rats exposed to 100 mg/m3 compared to the controls (17.8 sec (SD 1.9) vs. 19.5 sec (SD 2.4), respectively). However the values were well within the historical control range (12.0 - 21.9, mean 17.3 seconds) and minimally decreased coagulation times are not physiologically relevant; therefore, this change was considered to be non-adverse.

Clinical biochemistry findings:

effects observed, non-treatment-related

Description (incidence and severity):

Glucose was minimally decreased in rats exposed to 25 mg/m3. This change was considered to be unrelated to treatment because it did not occur in a dose-related manner.
Sodium was decreased in males exposed to 5 or 100 mg/m3. The mean and individual values were very similar in these 2 groups, while those of the control and 25 mg/m3 group were also similar to each other. Therefore, the change was unrelated to treatment and considered non-adverse.

Urinalysis findings:

effects observed, treatment-related

Description (incidence and severity):

Urine volumes were increased in some rats in all groups exposed to the test substance. Urine volumes were similar in rats exposed to 5 or 25 mg/m3, 7.3 mL (SD 4.5) and 7.0 mL (SD 4.7), respectively, and were minimally higher in males exposed to 100 mg/m3 at 8.6 mL (SD 3.2) (control 4.3 mL(SD 1.9)). However, urine volumes were within the historical control range (0.9 - 23.2 mL; mean 7.5 mL). Because of the lack of adverse changes in renal tests and the lack of macroscopic findings in the kidney, the increased volume in some animals was considered to be non-adverse, and likely secondary to increased water consumption as a result of the inhaled material.
Urine protein concentration was decreased in rats exposed to 100 mg/m3. However, the total protein excreted was similar across groups. Therefore, decreased urine protein concentratrion was considered to be a secondary effect to increased urine volume and therefore considered to be non-adverse.

Behaviour (functional findings):

not examined

Immunological findings:

not examined

Organ weight findings including organ / body weight ratios:

no effects observed

Gross pathological findings:

effects observed, non-treatment-related

Description (incidence and severity):

There were no exposure-related gross observations. Four gross observations were recorded. Two observations (renal pelvis dilatation and spleen deformity) were incidental lesions common to laboratory rats. Another observation (reproductive organ hermaphrodism) was a rare congenital anomaly of rats unrelated to the test substance exposure. The remaining observation (diffuse red foci of the lung in one animal in the 100 mg/m3 group) was an acquired lesion that correlated with mild microscopic granulomatous inflammation, probably due to aspiration (see also histopathological findings).

Neuropathological findings:

not examined

Histopathological findings: non-neoplastic:

effects observed, treatment-related

Description (incidence and severity):

There were no adverse, test material-related microscopic effects observed in the respiratory tract. Normal numers of pulmonary alveolar macrophages contained minimal to mild (grades 1 - 2) amounts of intracytoplasmic particulates consistent with the test material. Minimal to mild amounts of intracytoplasmic particulates were also observed within macrophages present within the respiratory tract lymphoid tissue (bronchial and retropharyngeal lymphoid tissue). There was no evidence of increased macrophage numbers, inflammation, or fibrosis resulting from the test material. Considering the lack of inflammation and fibrosis, the phagocytosis of the test material was consistent with the respiratory tract's response to a non-pathogenic nuisance dust.

One rat exposed to 100 mg/m3 of the test material had mild (grade 2) granulomatous inflammation of the lung that correlated with red foci observed at necropsy. Large pieces (>25 um) pieces of weakly birefringent foreign material, resembling plant material, were observed in giant cells in the lesion and were likely responsible for the giant cell formation. Therefore, the granulomatous inflammation in the rat was most likely due to aspiration of stomach contents and unrelated to test material exposure.

Effect levels

Key result

Dose descriptor:

NOAEL

Effect level:

>= 100 mg/m³ air (analytical)

Based on:

test mat.

Sex:

male

Basis for effect level:

other: No adverse effects at highest dose tested; only non-adverse respiratory tract effects at all exposure concentrations.

Target system / organ toxicity

Critical effects observed:

not specified

Applicant's summary and conclusion

Conclusions:

In a 2-week whole body aerosol inhalation study, the no observed adverse effect level (NOAEL) for male rats exposed to Terracess L was 100 mg/m³ based on the absence of adverse effects at all exposure concentrations.

Executive summary:

A two-week inhalation study in male rats was performed similar to OECD TG 412 and according to GLP principles. Groups of 10 male rats per dose were exposed to aerosols of the test substance dust at actual mean concentrations of 4.8, 26 and 100 mg/m³. Aerosol concentrations were measured gravimetrically. The mass median aerodynamic equivalent diameter of the aerosols ranged from 2.9 to 3.3 µm. Rats were exposed whole-body for 6 hours per day for a total of 9 exposures over a two week period. A similarly comprised control group of 10 male rats was simultaneously exposed to air only. On the day following the last exposure, blood and urine samples were collected for clinical analyses from each rat, and all rats were sacrificed for anatomic pathology examination. Only the respiratory tract was examined histologically. No deleterious effects were observed in clinical observations during the study and body weights were similar in test and control rats. Clinical pathology evaluations showed no adverse effects on hematology, coagulation, clinical chemistry, and urine parameters as a result of exposure to the test item. Weight analysis of the lung and brain showed no significant difference between test and control rats. There were no adverse histological findings in the respiratory tract, including the nose, larynx/pharynx, trachea, and lungs. The only significant observation was the presence of engulfed test particles in the resident macrophages in the lung of all exposure groups, which is typical of a 'nuisance dust' response.

Based on the lack of significant adverse effects after exposure to the test compound, the no observed adverse effect level (NOAEL) for sub-acute repeated inhalation exposure was 100 mg/m³ for male rats.