Magnesium potassium titanium oxide

Repeated dose toxicity: inhalation

Administrative data

Endpoint:

sub-chronic toxicity: inhalation

Type of information:

experimental study

Adequacy of study:

key study

Study period:

January 16, 2006 - June 28, 2007

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: Performed according to EPA and OECD test guidelines and according to GLP.

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2007

Report date:

2007

Materials and methods

Test guideline

Test guideline 1

Qualifier:

according to guideline

Guideline:

OECD Guideline 413 (Subchronic Inhalation Toxicity: 90-Day Study)

Test guideline 2

Qualifier:

according to guideline

Guideline:

EPA OPPTS 870.3465 (90-Day Inhalation Toxicity)

GLP compliance:

yes

Test material

Test material information

Constituent 1

Reference substance name:

-

EC Number:

436-900-9

EC Name:

-

Cas Number:

39290-90-9

Molecular formula:

Hill Empirical formula: K(0.2-0.7) Mg(0.4) Ti(1.6) O(3.7-3.95) CAS Empirical formula: K(0.2-0.7) Mg(0.4) Ti(1.6) O(3.7-3.95)

IUPAC Name:

Magnesium Potassium Titanium Oxide

Details on test material:

- Name of test material (as cited in study report): Terracess PS (Magnesium Potassium Titanium Oxide)
- CAS no: 39290-90-9
- Physical state: White powder
- Analytical purity: 99.4%
- Lot/batch No.: 2E93A
- Stability: known to be a stable, inorganic solid, therefore no analyses were conducted for stability.

Test animals

Species:

rat

Strain:

other: Crl:CD(SD)

Sex:

male/female

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Source: Received from Charles River Laboratories, Inc., Raleigh, North Carolina.
- Age at study initiation: approx. 5 weeks
- Weight at study initiation: males, 141-195 grams; females, 126-175 grams.
- Fasting period before study:
- Housing: Stainless steel, wire-mesh cages suspended above cage boards. During quarantine, pretest, exposure and recovery phases, animals were housed singly.
- Diet (e.g. ad libitum): Except during exposures, PMI® Nutrition International, LLC Certified Rodent LabDiet® 5002
and tap water were available ad libitum. During the urine collection period, animals were fasted
overnight for 12 to 20 hours after approximately one to 3 hours of access to food following
exposure; water, however, was available ad libitum.
- Water (e.g. ad libitum):
- Acclimation period: 2 weeks

ENVIRONMENTAL CONDITIONS
- Temperature (°C): 22 ± 3ºC
- Humidity (%): 50 ± 20%.
- Air changes (per hr): 10/hr
- 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 4 times per test level over the course of the daily exposure period. The MMAD of the aerosols ranged from 4.1 to 4.8 μm. About 20% of particle mass was less than 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 jetmill. The test substance was metered into the jetmill with a Schenck Accurate model 102M bin feeder. High-pressure air, metered into the Jet-OMizer by a distribution manifold, carried the resulting atmosphere into the exposure chamber. Dilution air, delivered with a rotometer, was added to the chambers to achieve the desired concentration. Chamber concentrations of test substance were also controlled by varying the feed rate or airflow to the atmosphere generator. Custom-made timer/controllers were used in conjunction with the bin feeder to achieve finer control of the 2 and 10 mg/m³ chambers. Air was delivered to the control chamber using the same type of Jet-O-Mizer/rotometer system as that used in the test chambers. Test atmospheres were exhausted through a high-capacity particle filter prior to discharge into the fume hood. The control chamber atmosphere was exhausted through an MSA charcoal/HEPA filter cartridge prior to discharge into the fume hood.
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.

TEST ATMOSPHERE
- Brief description of analytical method used:
- Samples taken from breathing zone: yes/no

VEHICLE (if applicable)
- Justification for use and choice of vehicle:
- Composition of vehicle:
- Type and concentration of dispersant aid (if powder):
- Concentration of test material in vehicle:
- Lot/batch no. of vehicle (if required):
- Purity of vehicle:

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:

90-day, 67 exposures

Frequency of treatment:

6 h/d, 5d/w

Doses / concentrations

Remarks:

Doses / Concentrations:
2.0, 10, 50 mg/m3
Basis:
analytical conc.

No. of animals per sex per dose:

20 males, 15 females

Control animals:

other: air only

Details on study design:

- Dose selection rationale: Based on the acute inhalation toxicity study and a 2 week inhalation study, the concentrations were chosen.
- Rationale for animal assignment (if not random): Rats of each sex were selected for use on study based on adequate body weight gain and freedom from any ophthalmology abnormalities or clinical signs of disease or injury. They were distributed by computerized, stratified randomization into study groups as designated in the Study Design, so that there were no statistically significant differences among group body weight means within a sex. At the start of the study, the weight variation of selected rats did not exceed ± 20% of the mean weight for each sex. The first 10 male and 10 female rats in each group were designated for sacrifice at the end of the exposure period. After an approximately one-month recovery period, 5 male rats per group were sacrificed. The remaining rats were sacrificed at the end of the approximately 3-month recovery period.
- Rationale for selecting satellite groups:
- Post-exposure recovery period in satellite groups: Two recovery periods of approximately one and three months duration were in place. During the recovery periods, exposures were not conducted: however, in-life observations and measurements (clinical observations and body weights) were continued. One month recovery group: 5 male rats/dose. Three month recovery group: remaining male and female rats, approx 4-5 rats/sex/dose. Since the substance related effects were observed only in the respiratory tract of the main study, microscopic evaluation of the three month recovery group was limited to tissues of the respiratory tract and gross lesions.
- Section schedule rationale (if not random):

Positive control:

Not relevant.

Examinations

Observations and examinations performed and frequency:

An ophthalmology evaluation was conducted prior to the initiation of exposures and near the end of the exposure period.
Body weights and food consumption were determined on Day 0 and weekly thereafter.
Clinical observations were evaluated daily following exposures.
Detailed clinical observations were determined on Day 0 and weekly thereafter.

Sacrifice and pathology:

On the day following the last exposure, blood and urine samples were collected for clinical pathology analyses from 10 rats per sex per group, and these rats were sacrificed for anatomic pathology examination. After the conclusion of the exposure phase there were 2 recovery periods of approximately 1 and 3 months. At the one month recovery, 5 male rats per group were sacrificed and given anatomic pathology examinations; the remaining male and female rats were sacrificed approximately 3 months after exposure and also given anatomic pathology examinations. These included gross observations, organ weights and lung titanium analysis.

Other examinations:

Near the end of the exposure period, a functional observational battery and motor activity were conducted. Post necropsy, lung titanium analyses were conducted (ICPS) at 3 times during this study in groups of 5 male rats per group per time period.

Statistics:

Significance was judged at p < 0.05. Separate analyses were performed on the data collected for each sex.
Method of Statistical Analysis:
Exposure Concentration Data, Environmental Data, Lung Titanium Analysis: Descriptive statistics (e.g., mean, standard deviation).
Body Weight, Body Weight Gain, Food Consumption, Food Efficiency, 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 significan.t
Motor Activity, Grip Strength: Levene’s test for homogeneity and Shapiro-Wilk test for normality in preliminary test. Repeated measures analysis of variance followed with Linear contrasts if preliminary test is not significant. Sequential application of the Jonckheere-Terpstra trend test is preliminary test is significant.
Incidence of FOB, Descriptive Parameters: 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):

no effects observed

Food efficiency:

no effects observed

Ophthalmological findings:

no effects observed

Haematological findings:

no effects observed

Clinical biochemistry findings:

no effects observed

Urinalysis findings:

no effects observed

Behaviour (functional findings):

no effects observed

Organ weight findings including organ / body weight ratios:

no effects observed

Gross pathological findings:

no effects observed

Histopathological findings: non-neoplastic:

no effects observed

Details on results:

Prior to the initiation of the range finder, the concentration of Terracess PS at 9 different points was found to be within 10% of the mean concentration. This was considered to be sufficient indication of homogeneity of the test substance in the chamber.
The mean, gravimetrically determined, aerosol concentrations for the exposures were 2.0, 10, and 50 mg/m³. The mass median aerodynamic equivalent diameter (MADD) of the Terracess PS dust measured in the test atmospheres ranged from 4.1 to 4.8 μm. Geometric standard deviations
ranged from 1.2 to 1.8. About 20% of the particle mass was less than 3 μm.

BODY WEIGHTS AND BODY WEIGHT GAINS:
No substance related effects observed.

FOOD CONSUMPTION AND FOOD EFFICIENCY:
No substance related effects were observed.

CLINICAL OBSERVATIONS:
The only clinical observation of note was hair loss found sporadically in all groups. This is a common finding in inhalation studies in rats, and thus not considered to be due to the substance.

OPHTHALMOLOGY:
The ophthalmology exam conducted near the end of the exposure phase of the study showed focal retinal degeneration in 2 male rats, one each in the 10 and 50 mg/m³ groups. This is a common finding in rats and was not considered to be substance related.

NEUROLOGICAL BEHAVIOUR:
No substance related effects were observed on forlimb grip strength, hindlimb grip strength, open field observations, and motor activity.
Males in the 2 mg/m³ group had significantly higher forelimb grip strength compared to the control value. However, forelimb grip strength values for males in the 10 and 50 mg/m³ groups were similar to control; and therefore, the significantly higher value for the 2 mg/m³ males was not substance related. Males in the 2 mg/m³ group had significantly lower mean total number of movements. However, the total number of movements for the 10 and 50 mg/m³ were similar to the control value; and therefore, the significantly higher value for the 2 mg/m³ males was not substance related.

HAEMATOLOGY:
No treatment related or adverse changes in hematology parameters were present.
White blood cell, neturophil and lymphocyte counts were decreased in males exposed to all concentration groups, although all treated groups had similar means and individual counts. The apparent decrease in cell counts, resulted from increased white blood cell counts in three control animals. Excluding these three animals, resulted in comparable results between control and treated groups. In addition, no effects were found in females, no microscopic changes, thus effect was unrelated to treatement and non-adverse. Red cell distribution width was minimally decreased in males in the high dose group. No associated changes were present in red blood cell mass parameters or microscopic morphology, and thus not considered related to treatement and non-adverse.

CLINICAL CHEMISTRY:
No treatment related chagnes in clinical chemistry parameters.
The alkaline phosphatase activity was mnimally but statistically significant increased in females in the high dose group, due to the narrow range of activities. In addition, no anatomic pathology correlates to this change, and no changes in males. Therefore not considered related to treatement.
Chloride was minimally increase in males in the low dose group, however no dose related pattern and thus not considered treatement related.

URINALYSIS:
No treatment related effects.

MORTALITY:
Two deaths were interpreted to be incidental and not related to exposure. One male rat was accidentally killed during blood collection due to an anesthetic overdose, no gross or microscopic effects found. One female was euthanized following the accidental fracture of its nose.

ORGAN WEIGHTS:
No substance related effects on organ weights.
In females exposed to the highest concentration (50 mg/m³), there were small, statistically significant, decreases in mean absolute liver (11%) and heart (10%) weights, as compared to control values. These decreases were associated with a slight decrease (5%) in mean absolute final body weight, mean relative (% body weight) liver and heart weights were not statistically decreased, there were no organ weight effects in male rats, and there were no gross or microscopic test substance-related effects in the livers and hearts of either males or females.

GROSS PATHOLOGY:
No substance related effects. All gross observations recorded in this study, at all intervals, were consistent with normal background lesions in rats of this age and strain.

MICROSCOPIC FINDINGS:
There was no evidence of increased macrophage numbers, inflammation, or fibrosis. Rats allowed to recover for approximately 30 (males only) and 90 days demonstrated migration of pulmonary macrophages into aggregates and gradual clearance of test substance. The microscopic findings were consistent with exposure to a non-pathogenic nuisance dust.
There were no adverse test substance-related microscopic effects observed in the respiratory tract. Non-adverse accumulation of test substance within macrophages was observed in respiratory tract macrophages. Test substance related findings were not observed within any non-respiratory tract tissues. Microscopic examination of males and females following the 90-day exposure demonstrated no differences between the sexes.
The incidence and severity of particulate-laden macrophages within lymphoid tissue also appeared to be similar in the rats following either the 90-day exposure or the 30-day or 90-day recovery period.

Effect levels

Dose descriptor:

NOAEL

Effect level:

>= 50 mg/m³ air

Based on:

test mat.

Sex:

male/female

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

Any other information on results incl. tables

In rats exposed to dust of the substance, lung titanium concentrations at the end the exposure period were roughly proportional to the exposure concentrations. There were no significant background titanium levels found in the control group. The clearance half-times for Terracess PS were estimated to be approximately 2 ½ months for the 2 and 10 mg/m³ groups and approximately 4 months for the 50 mg/m³ group.

Applicant's summary and conclusion

Conclusions:

Under the conditions of this study, a 90-day whole body aerosol inhalation study, the no-effect level (NOEL)a for rats exposed to Terracess PS
for approximately 90 days was 50 mg/m³ based on the finding of only non-adverse respiratory tract effects at all exposure concentrations.