Registration Dossier

Administrative data

Description of key information

Oral: No data available, oral exposure of the general public via the environment is not possible due to the fast hydrolysis of TiCl4 to TiO2 and HCl. Further, titanium tetrachloride is exclusively used in industrial settings with strict risk management measures in place.

Dermal: No data available. Due to the corrosive properties of the substance, effective risk management measures are in place protecting also against long-term effects.

Inhaltion: Two year inhalation study in rat (vapour): the Low Observed Effect Concentration (LOAEC) for local irritation of the airways was 0.1 mg/m³.

Key value for chemical safety assessment

Repeated dose toxicity: via oral route - systemic effects

Endpoint conclusion
Endpoint conclusion:
no study available

Repeated dose toxicity: inhalation - systemic effects

Endpoint conclusion
Endpoint conclusion:
no study available

Repeated dose toxicity: inhalation - local effects

Link to relevant study records
Reference
Endpoint:
chronic toxicity: inhalation
Type of information:
experimental study
Adequacy of study:
key study
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: The study was not conducted according to GLP but followed a protocol that is similar to OECD Test Guideline 452.
Qualifier:
equivalent or similar to
Guideline:
OECD Guideline 452 (Chronic Toxicity Studies)
Deviations:
no
GLP compliance:
no
Limit test:
no
Species:
rat
Strain:
Sprague-Dawley
Sex:
male/female
Details on test animals and environmental conditions:
TEST ANIMALS
- Strain: Crl:CD (SD)BR
- Source: Charles Rivers Breeding Laboratories, Wilmington, Massachusetts
- Weight at study initiation: not reported
- Fasting period before study: None
- Housing: Housed in pairs in stainless steel wire-mesh cages 14 x 8 x 8 inches
- Diet: Purina Laboratory Chow Checkers #5001, ad libitum
- Water: ad libitum
- Acclimation period: 14 days


ENVIRONMENTAL CONDITIONS
- Temperature (°C): 23 ± 2
- Humidity (%): 50 ± 10
- Photoperiod (hrs dark / hrs light): 12/12


IN-LIFE DATES: From: 1979 To: 1981
Route of administration:
inhalation: dust
Type of inhalation exposure:
whole body
Vehicle:
other: unchanged (no vehicle)
Remarks on MMAD:
MMAD / GSD: MMAD (10 mg/m3 test chamber) = 0.5 µm
The aerodynamic diameter (AD) of chamber particulates was determined twice at the 10 mg/m concentration with a Brink Cascade impactor (Brink, 1958).
The respirable fraction of hydrolysis products within the chamber atmosphere was reported to be virtually 100%.
Details on inhalation exposure:
GENERATION OF TEST ATMOSPHERE / CHAMBER DESCRIPTION
- Exposure apparatus: stainless steel (Hastelloy-C) exposure chambers, 3.8 cubic metres, with vertical-opening, hydraulically operated doors.
- Air flow: 1000 litres/minute.
- Generation of test atmosphere: Titanium tetrachloride vapours were generated by passing nitrogen over liquid TiCl4 in a glass vessel placed in a
20°C constant temperature ethylene glycol bath. The test substance fumes on contact with moist air, liberating hydrochloric acid, titanium
oxychlorides and titanium dioxide.
- Temperature, humidity, pressure in air chamber: 23 ± 2°C; 50 ± 10% relative humidity; slightly negative pressure to prevent release of test
substance into chamber room.
- Method of particle size determination: Brink cascade impactor

TEST ATMOSPHERE
- Brief description of analytical method used: Chamber atmospheres were monitored by trapping solid TiCl4 hydrolysis products on cellulose acetate filters which were analysed for titanium content using a colorimetric method.
Analytical verification of doses or concentrations:
yes
Details on analytical verification of doses or concentrations:
- Chamber atmospheres analysed at least once per hour.
- Method:
trapping of solid TiCl4 hydrolysis products on cellulose acetate filters
analysis of titanium content using a colorimetric method.
The method was referenced as an unpublished DuPont method (Ringwald, 1979). No further details are given in the test report.
- Measured concentrations are reported as mg/m3 TiCl4, calculated from the total titanium determined.
Duration of treatment / exposure:
2 years, 6 hours per day.
Frequency of treatment:
5 days per week.
Remarks:
Doses / Concentrations:
0, 0.1, 1.0 and 10 mg/m3
Basis:
nominal conc.
No. of animals per sex per dose:
100/sex/dose
Control animals:
yes, sham-exposed
Details on study design:
- Dose selection rationale: 28-day sub-acute inhalation toxicity test
- Rationale for animal assignment: computerized, stratified randomization
- Section schedule rationale: Serially, from the last five (at three months) and randomly at 6 and 12 months

Positive control:
no
Observations and examinations performed and frequency:
CAGE SIDE OBSERVATIONS: Yes
- Time schedule: Daily

DETAILED CLINICAL OBSERVATIONS: Yes
- Time schedule: once per week during first three months and then once every other week for the remainder of the study.

BODY WEIGHT: Yes
- Time schedule for examinations: once per week during the first three months and then twice monthly for the remainder of the study.

FOOD CONSUMPTION: No

FOOD EFFICIENCY: No

WATER CONSUMPTION: No

OPHTHALMOSCOPIC EXAMINATION: No

HAEMATOLOGY: Yes
- Time schedule for collection of blood: 3, 6, 12, 15 and 18 months after study initiation
- Anaesthetic used for blood collection: No data
- Animals fasted: Yes
- How many animals: 10 per test group plus controls
- Parameters checked in table 1 were examined.


CLINICAL CHEMISTRY: Yes
- Time schedule for collection of blood: 3, 6, 12, 15 and 18 months after study initiation
- Animals fasted: Yes
- How many animals: 10 per test group plus controls
- Parameters checked in table 1 were examined.


URINALYSIS: Yes
- Time schedule for collection of urine: 3, 6, 12, 15 and 18 months after study initiation
- Metabolism cages used for collection of urine: Yes
- Animals fasted: Yes
- Parameters checked in table 1 were examined.


NEUROBEHAVIOURAL EXAMINATION: No
Sacrifice and pathology:
GROSS PATHOLOGY: Yes (full pathology reports not available)
HISTOPATHOLOGY: Yes (full histopathology reports not available)
Statistics:
- Body weight and weight gain data were evaluated with a one-way analysis of variance and the least significant difference (LSD) test.
- Organ weight data were evaluated with a one-way analysis of variance with pairwise comparisons being made with the LSD and/or Dunnett's tests. The Bartlett test was also used to evaluate the organ weight data.
- Clinical laboratory data were evaluated by a partially nested and crossed analysis of variance and by the least significant difference (LSD) test.
Significance was judged at the 5% level of probability.
Clinical signs:
effects observed, treatment-related
Mortality:
mortality observed, treatment-related
Body weight and weight changes:
effects observed, treatment-related
Food consumption and compound intake (if feeding study):
not specified
Food efficiency:
not specified
Water consumption and compound intake (if drinking water study):
not specified
Ophthalmological findings:
not examined
Haematological findings:
effects observed, treatment-related
Clinical biochemistry findings:
no effects observed
Urinalysis findings:
no effects observed
Behaviour (functional findings):
not examined
Organ weight findings including organ / body weight ratios:
effects observed, treatment-related
Gross pathological findings:
effects observed, treatment-related
Histopathological findings: non-neoplastic:
effects observed, treatment-related
Histopathological findings: neoplastic:
effects observed, treatment-related
Details on results:
All results presented here are based on the findings of the final sacrifice after 2 years if not stated otherwise.

CLINICAL SIGNS AND MORTALITY:
Clinical signs
- males:
Irregular respiratory noise (rales): incidence and median day of first notice are dose dependent
- females:
Irregular respiratory noise (rales): median day of first notice is dose dependent, incidence not dose dependent
Pallor: raised in exposed groups, not dose dependent
Stained perineum: raised in exposed groups, not dose dependent
all other findings occurred with similar incidence in controls and exposed animals
see Table 2 for details
Mortality
The mortality rates for all treatment groups within each sex were similar to those of the control groups. Mortality rates for females were 1.2 to
1.5-fold higher than those for males.

BODY WEIGHT AND WEIGHT GAIN
1.0 and 10 mg/m³:
- males: Mean body weights were slightly lower (1-8% lower) than those of the common controls and were not dose-related.
- females: generally not different from controls. However, from weeks 94 to 106, mean body weights of exposed females were 4 to 16% greater than those of their common controls.
Overall, mean body weight gains varied slightly in the 1.0 and 10 mg/m³ dose levels for both sexes when compared to their respective control
groups (See Table 2).


HAEMATOLOGY
- 0.1 mg/m³:
females: at 18 months a statistically significant increase in leucocytes.
- 10 mg/m³:
males and females: at 18 months a statistically significant increase in neutrophils and a decrease in lymphocytes.
males only: statistically significant decrease in erythrocytes and increases in mean cell volume and mean cell haemoglobin
- All other clinical chemistry parameters were within the expected range of biological variability for this species.

CLINICAL CHEMISTRY
- 10 mg/m³:
males: a statistically significant increase in serum bilirubin at final sacrifice
- All other clinical chemistry parameters were within the expected range of biological variability for this species.


URINALYSIS
All urinalysis parameters were within the expected range of biological variability for this species.


ORGAN WEIGHTS
Lungs:
- 10 mg/m³:
males: a relative lung weight difference at the six-month sacrifice.
males and females: significantly greater mean absolute and relative lung weights in the one and two-year sacrifices (rather trough tissue response then through test item deposition).
- See table 3 for details
Liver:
- all treatment groups:
males: generally lower mean absolute and/or relative liver weights at the three-month, one and two-year sacrifices.
In the absence of histopathological lesions, these changes are deemed non-adverse.
- See table 3 for details
Kidneys:
- all treatment groups:
males: significantly lower mean absolute kidney weights at three months and two years. In the absence of a clear dose response these changes are deemed non-adverse.

Significant but transient effects were observed for other organ weights over the course of the study. These effects were either related to body weight differences or were not considered to be biologically significant.


GROSS PATHOLOGY
Respiratory system
- 0.1 mg/m³:
males and females: no abnormalities
- 1.0 mg/m³: very sparsely scattered yellow foci laden with TiCl4 hydrolysis product in the lungs, tracheobronchial lymph nodes were slightly enlarged and mottled with yellow TiCl4 hydrolysis product laden foci
- 10.0 mg/m³: high number of yellow foci laden with TiCl4 hydrolysis product in the lung, tracheobronchial lymph nodes were slightly enlarged and mottled with yellow TiCl4 hydrolysis product laden foci


HISTOPATHOLOGY: NON-NEOPLASTIC
Respiratory system
The respiratory tract was the primary deposition site for TiCl4 hydrolysis products as well as the primary site in which a tissue response to the test substance was observed.
-0.1 mg/m³, males and females:
the incidence of rhinitis and tracheitits increased over that of controls;
lungs maintained their normal architecture;
a few dust cells in the alveoli adjacent to the alveolar duct;
no tissue responses to the dust in the alveoli;

None of these findings were apparent at the one-year sacrifice.

- 1.0 mg/m³, males and females:
an increased incidence of rhinitis as well as tracheitis;
small dust cell aggregates were found, mainly in the alveolar, ducts and adjoining alveoli, but alveoli in the peripheral acini were normal;
light hyperplasia of the alveolar lining cells (Type II pneumocytes) with no collagen fibre deposition in the alveoli enclosing dust cell aggregates

Most of these findings were apparent at the one-year sacrifice.

The authors of the study considered the pulmonary response to be reversible and characteristic of a nuisance dust.

- 10 mg/m³ , males and females:
an increased incidence of rhinitis and tracheitis;
test substance-related pathological lesions included a dust cell response with Type II pneumocyte hyperplasia, foamy macrophage infiltration, cholesterol granumlomas with collagen fibre deposition, alveolar proteinosis and alveolar bronchiolarization.

Rhinitis, tracheitis and dust cell responses were observed as early as the three-month sacrifice and the remaining effects were observed at the two-year sacrifice.

Tracheobronchial lymph nodes, liver and spleen
- 1.0 and 10 mg/m³, males and females:
dose-related transmigration of dust particles from the lung through the lymphatics to the tracheobronchial lymph nodes, liver and spleen;
no significant tissue responses to the particle deposition in the lymph nodes;
- 10 mg/m³, males and females:
in the spleen, dust particle aggregates were primarily located in the lymphoid tissue of the white pulp, while the red pulp exhibited minute dust particle deposition in the reticuloendothelial cells;
in the liver, particles accumulated in the Kupffer cells and portal triads;
no significant tissue response in either liver or spleen

At the three-month sacrifice, all exposed groups showed evidence of murine pneumonia. The pneumonic lesions were indicative of those induced by Corynebacterium kutscheri infection. These lesions overshadowed and may have exacerbated the pulmonary response to the hydrolysis products of TiCl4. However, after six months exposure the pneumonic lesions had disappeared. The authors therefore concluded that the murine pneumonia did not alter the final results of the study.


HISTOPATHOLOGY: NEOPLASTIC

- 10 mg/m³, males and females:
microscopic, well-differentiated squamous cell carcinomas and cystic keratinised squamous cell carcinomas;
total incidence of the squamous cell carcinomas: 2/75 in males and 3/75 in females;
all squamous cell carcinomas so well-differentiated that it was extremely difficult to distinguish them from squamous cell metaplasia;
bronchioalveolar ademona observed were not associated with exposure to the test substance;

Because similar lesions were observed in rat lungs after high-dose, chronic exposure to other particulates such as para-aramid fibrils, chromium dioxide, and titanium dioxide; it was suggested that this may be indicative of a normal, biological response. Accordingly, the lesions were subsequently re-examined by a panel of four pathologists (Frame and Slone 1995) and unanimous agreement was reached for the diagnosis of each of the lesions examined:
"Cystic keratinizing squamous lesions were produced in rats following chronic exposure to high concentrations of TiC14 . These lesions were evaluated by four pathologists using recently proposed diagnostic criteria. Unanimous agreement was reached as to the diagnosis of each of the lesions. Three of the lesions were diagnosed as squamous metaplasia and two as pulmonary keratin cyst. Although the epithelial lining of some of
these cysts had varying degrees of irregularity, most other criteria given for epithelioma were absent."
Dose descriptor:
LOAEC
Remarks:
local
Effect level:
0.1 mg/m³ air
Based on:
test mat.
Sex:
male/female
Basis for effect level:
other: increased rhinitis and tracheitis in the lowest exposure group
Critical effects observed:
not specified

- Mean weekly chamber concentrations of TiC14 over the course of the study:

low concentration: 0.10 ± 0.02 mg/m3 (planned 0.1 mg/m3)

mid concentration: 1.0 ± 0.10 mg/m3 (planned 1.0 mg/m3)

high concentration: 10.1 ± 0.6 mg/m3 (planned 10.0 mg/m3)

Concentrations were achieved with an acceptable range of variation from the mean (6 to 18%).

 

- Table 2: Relevant Clinical Observations

Observation

Number of rats exhibiting sign

(median day of first notice)

Males

Group:

Concentration (mg/m3):

I
0

III
0.1

V
1.0

VII

10.0

Irregular respiration/lung noise

8

(661)

12

(555)

24

(409)

36

(227)

Females

Group:

Concentration (mg/m3):

II
0

IV
0.1

VI
1.0

VIII

10.0

Irregular respiration/lung noise

8

(542)

16

(481)

44

(383)

41

(71)

Pallor

12

(655)

23

(600)

24

(612) 

20

(615)

Stained perineum

0

 

15

(421)

9

(547)

8

(515)

- Table 3: Mean bodyweights (BW) and bodyweight gains (BWG)a

 

0

0.1 mg/m³

1.0 mg/m³

10 mg/m³

MALES Initial BW

131.6

130.5

131.2

130.7

BWG Wk -2-13 (g/d)

4.315

4.123

4.003

4.045

BWG Wk 13-26 (g/d)

0.947

1.141

1.089

1.121

BWG Wk 26 -52 (g/d)

0.702

0.712

0.644

0.640

BWG Wk 52 -78 (g/d)

0.359

0.347

0.381

0.294

BWG Wk 78 - 106 (g/d)

-0.232

0.032

-0.027

0.045

Overall BWG Wk -2 - 106 (g/d)

0.947

0.957

0.950

0.936

FEMALES Initial BW

127.3

122.1

129.8

120.4

BWG Wk -2 -13 (g/d)

2.584

2.504

2.448

2.390

BWG Wk 13 -26 (g/d)

0.518

0.560

0.733

0.733

BWG Wk 26 -52 (g/d)

0.595

0.575

0.555

0.636

BWG Wk 52 -78 (g/d)

0.497

0.370

0.500

0.476

BWG Wk 78 - 106 (g/d)

-0.084

0.196

0.128

0.054

BWG Wk -2 -106 (g/d)

0.600

0.692

0.664

0.705

a: Data obtained from pages 54 -59 in the study report.

- Table 3: Relative organ weights

Time point

Gender

Group

Concentration

Lungs

Liver

Kidneys

3 months

male

I  

0 mg/L   

0.395 (0.039)

3.820 (0.265)

0.747 (0.062)

III  

0.1 mg/L   

0.440 (0.034)

3.430 (0.114)#

0.731 (0.051)

V  

1.0 mg/L   

0.459 (0.023)

3.433 (0.211)#

0.726 (0.060)

VII  

10.0 mg/L   

0.462 (0.053)

3.422 (0.292)#

0.722 (0.060)

female

I  

0 mg/L   

0.546 (0.042)

3.817 (0.252)

0.759 (0.027)

III  

0.1 mg/L   

0.504 (0.100)

3.487 (0.384)

0.782 (0.102)

V  

1.0 mg/L   

0.547 (0.063)

3.353 (0.263)

0.738 (0.083)

VII  

10.0 mg/L   

0.454 (0.101)

2.846 (0.846)#

0.658 (0.174)

6 months

male

I  

0 mg/L   

0.364 (0.026)

3.431 (0.161)

0.615 (0.082)

III  

0.1 mg/L   

0.399 (0.037)

3.529 (0.166)

0.729 (0.081)

V  

1.0 mg/L   

0.386 (0.018)

3.411 (0.408)

0.642 (0.036)

VII  

10.0 mg/L   

0.431 (0.040)#

3.268 (0.156)

0.685 (0.079)

female

I  

0 mg/L   

0.468 (0.046)

3.286 (0.297)

0.716 (0.045)

III  

0.1 mg/L   

0.507 (0.030)

3.439 (0.121)

0.727 (0.048)

V  

1.0 mg/L   

0.459 (0.035)

3.482 (0.571)

0.650 (0.050)

VII  

10.0 mg/L   

0.485 (0.067)

3.633 (0.827)

0.633 (0.107)

12 months

male

I  

0 mg/L   

0.365 (0.028)

3.356 (0.345)

0.662 (0.074)

III  

0.1 mg/L   

0.343 (0.047)

3.039 (0.339)+

0.630 (0.081)

V  

1.0 mg/L   

0.358 (0.049)

2.992 (0.227)#

0.605 (0.057)

VII  

10.0 mg/L   

0.410 (0.042)+

3.046 (0.222)+

0.624 (0.075)

female

I  

0 mg/L   

0.408 (0.082)

3.276 (0.291)

0.629 (0.110)

III  

0.1 mg/L   

0.446 (0.067)

3.433 (0.598)

0.742 (0.112)

V  

1.0 mg/L   

0.387 (0.071)

3.270 (0.516)

0.617 (0.151)

VII  

10.0 mg/L   

0.506 (0.047)#

3.123 (0.219)

0.634 (0.079)

24 months

male

I  

0 mg/L   

0.411 (0.076.)

3.259 (0.950)

0.775 (0.215)

III  

0.1 mg/L   

0.405 (0.067)

3.054 (0.653)

0.698 (0.124)

V  

1.0 mg/L   

0.428 (0.075)

2.960 (0.471)+

0.669 (0.160)

VII  

10.0 mg/L   

0.559 (0.090)#

2.817 (0.457)#

0.699 (0.200)

female

I  

0 mg/L   

0.432 (0.083)

3.792 (0.849)

0.693 (0.105)

III  

0.1 mg/L   

0.411 (0.089)

3.428 (0.459)

0.640 (0.106)

V  

1.0 mg/L   

0.474 (0.197)

3.499 (0.640)

0.693 (0.157)

VII  

10.0 mg/L   

0.609 (0.155)#

3.305 (0.504)

0.639 (0.155)

Standard deviation in parentheses.

+ Significantly different (p < 0.05) from control group by LSD.

# Significantly different (p < 0.05) from control group by LSD and Dunnett's tests.

- Table 4: Main Pathological Lesions in the Nasal Cavity, Trachea and Lungs of Rats Exposed to TiC14 for Two Years

GROUP DESIGNATION:

I

male

II

female

III

male

IV

female

V

male

VI

female

VII

male

VIII

female

DOSE (mg/m³):

0

0.10

1.00

10.0

NUMBER IN GROUP:

79

77

77

75

78

78

75

75

TISSUE/LESION

 

 

 

 

 

 

 

 

NASAL CAVITY

79

76

73

73

73

77

73

69

Glandular hyperplasia, epithelium

1

-

5

1

-

-

6

2

Neoplasm, metastatic

1

-

2

-

1

-

-

-

Osteochondroma, ethmoid turbinate, posterior nasal cavity

-

-

-

-

1

-

-

-

Rhinitis, posterior nasal cavity

13

3

23

16

22

13

22

16

Rhinitis, anterior nasal cavity

25

18

47

46

41

33

48

38

Squamous metaplasia, anterior nasal cavity

8

7

8

8

9

8

6

11

Squamous metaplasia, posterior nasal cavity

 

1

 

 

 

 

 

 

TRACHEA

79

77

67

69

72

70

71

69

Neoplasm, metastatic

-

-

1

1

2

-

-

-

Tracheitis, chronic

2

-

8

13

35

29

31

21

THYMIC LYMPH NODES

63

51

49

49

56

44

61

64

Particulate dust deposition, thymic lymph nodes

-

-

-

-

22

11

48

56

LUNGS

79

77

77

75

78

78

75

75

Aggregates, foamy alveolar macrophage

14

8

8

3

10

13

49

61

Alveolar cell hyperplasia, TiC14 dust

-

-

-

-

49

25

69

73

Alveolar proteinosis

-

-

-

-

-

-

1

1

Bronchiolarization, alveoli

1

1

-

-

-

1

15

7

Bronchioloalveolar adenoma

2

-

-

-

1

-

1

1

Cholesterol granuloma

7

2

3

1

4

2

13

19

Keratinized, cystic squamous cell carcinoma

-

-

-

-

-

-

1

1

Pleurisy, fibrous, focal

4

2

-

-

-

1

9

8

Squamous cell carcinoma, well differentiated

-

-

-

-

-.

-

1

2

Particulate dust deposition, alveoli

-

-

-

2

71

76

66

69

Numbers in italics: number of animals that were analysed for lesions in the respective tissue

Regarding the relevance of carcinoma, please refer to the section "Details on results" where the result of a re-evaluation of these findings is described.

Conclusions:
The toxicity of TiCl4 was tested in Sprague Dawley rats in a 2 year chronic repeated dose study with inhalation treatment (6h/d, 5 d/wk; 0.1, 1.0 and 10 mg/m³).
A LOAEC of 0.1 mg/m³ was determined based on an increase in rhinitis and tracheitis in the lowest dose group compared to controls.
Executive summary:

The toxicity of TiCl4 was tested in Sprague Dawley rats in a 2 year chronic repeated dose study with inhalation treatment (6h/d, 5 d/wk; 0.1, 1.0 and 10 mg/m³).

A LOAEC of 0.1 mg/m³ was determined based on an increase in rhinitis and tracheitis in the lowest dose group compared to controls.
100 animals per sex and dose were full body exposed to fumes that were formed on contact of the test item with moist air, liberating hydrochloric acid, titanium oxychlorides and titanium dioxide. The MMAD (10 mg/m³ test chamber) = 0.5 µm indicates that at least part of formed particles belonged to the inhalable fraction.

METHODS:

Animals were observed daily for clinical signs and were weighted once per week during the first three months and then twice monthly for the remainder of the study. Clinical indices were measured in blood and urine after approximately 3, 6, 12, 15, and 18 months exposure. Gross and histopathological evaluations were conducted on 5 rats/sex/exposure group after 3 and 6 months exposure, on 10 rats/sex/exposure group after 12 months exposure, on all rats alive after 24 month exposure, and on all rats found dead or sacrificed extremis, tissue integrity permitting

 

RESULTS:

Clinical signs, Mortality and Body weight:

As clinical signs rales were noticed in all treatment groups, incidence and onset were generally dose dependent. In addition in females the incidence of pallor and stained perineum were raised in treatment groups, though not dose dependent. The mortality rates for all treatment groups within each sex were similar to those of the control groups. Bodyweights of treated males were slightly lower than controls (1-8 %) but no dose dependence was seen. In treated females body weights were generally not different from controls.

¨

Haematology:

Haematological parameters were generally unremarkable except for a statistically significant increase in leucocytes in 0.1 mg/m³ females at 18 months, a statistically significant increase in neutrophils and a decrease in lymphocytes in the 10 mg/m³ group at 18 months and finally a statistically significant decrease in erythrocytes and increases in mean cell volume and mean cell haemoglobin in males of the 10 mg/m³ group at 18 months. As no time dependences and no dose dependences was seen for these effects and as no histopathological aberrations were noticed in the haematopoietic system, these effects are judged to be not treatment related.

 

Clinical chemistry:

Clinical chemical parameters were unremarkable except for a statistically significant increase in serum bilirubin at final sacrifice in males of the 10 mg/m³ group. As no histopathologic abnormalities were seen in the liver, this finding was regarded as non-adverse.

 

Urinalysis:

All urinalysis parameters were within the expected range of biological variability for this

 

Organ weights:

Regarding organ weights mainly effects in the lungs were seen. In 10 mg/m³ males a relative lung weight difference at the six-month sacrifice was found and after 12 and 24 months in both males and females of the 10 mg/m³ group significantly greater mean absolute and relative lung weights. The increase was interpreted as tissue response rather then an effect of test item deposition. In liver and kidney absolute and/or relative organ weigh reductions were noticed mainly in the high dose group at different time points. Nevertheless as no histopathologic abnormalities were seen in either tissue, these findings were regarded as non-adverse.

 

Gross necroscopy:

Gross necroscopy revealed significant differences between the different dose groups in the lungs. In the 0.1 mg/m³ dose group no abnormalities where found while in the 1.0 mg/m³ group very sparsely scattered yellow foci laden with TiCl4 hydrolysis product in the lungs were seen along with slightly enlarged tracheobronchial lymph nodes that were mottled with yellow TiCl4 hydrolysis product laden foci. Correspondingly at 10.0 mg/m³ a high number of yellow foci laden with TiCl4 hydrolysis product was noticed in the lung and tracheobronchial lymph nodes were enlarged and mottled with yellow TiCl4 hydrolysis product laden foci.

 

Histopathology:

The respiratory tract was the primary deposition site for TiCl4 hydrolysis products as well as the primary site in which a tissue response to the test substance was observed in the At 0.1 mg/m³ in both males and females the incidence of rhinitis and tracheitits increased over that of controls (21 of 136 in treatment group, 2 of 156 in controls). Lungs nevertheless maintained their normal architecture. A few dust cells in the alveoli adjacent to the alveolar duct were found but no tissue responses to the dust in the alveoli. None of these findings were apparent at the one-year sacrifice. In the 1.0 mg/m³ groups an increased incidence of rhinitis as well as tracheitis was noticed, small dust cell aggregates were found, mainly in the alveolar, ducts and adjoining alveoli, but alveoli in the peripheral acini were normal. Additionally a light hyperplasia of the alveolar lining cells (Type II pneumocytes) without collagen fibre deposition in the alveoli enclosing dust cell aggregates was reported. Most of these findings were apparent already at the one-year sacrifice.

The authors of the study considered the pulmonary response at 0.1 and 1.0 mg/m³ to be reversible and characteristic of a nuisance dust.

Nevertheless based on a re-assessment of the raw data on tracheitis these effects are deemed severe and adverse and therefore relevant for the derivation of a LOAEC.

In high dose (10 mg/m³) males and females a further increased incidence of rhinitis and tracheitis was noted and test substance-related pathological lesions included a dust cell response with Type II pneumocyte hyperplasia, foamy macrophage infiltration, cholesterol granumlomas with collagen fibre deposition, alveolar proteinosis and alveolar bronchiolarization. Rhinitis, tracheitis and dust cell responses were observed as early as the three-month sacrifice and the remaining effects were observed at the two-year sacrifice.

Secondary to the processes in the lung dose-related transmigration of dust particles from the lung through the lymphatics to the tracheobronchial lymph nodes, liver and spleen were seen in the 1.0 and 10 mg/m³ groups of both sexes. In the spleen, dust particle aggregates were primarily located in the lymphoid tissue of the white pulp, while the red pulp exhibited minute dust particle deposition in the reticuloendothelial cells. In the liver, particles accumulated in the Kupffer cells and portal triads. As no histopathologic abnormalities were seen in these tissues, these findings were regarded as non-adverse.

At the highest dose (10 mg/m³) the authors of the original report described neoplastic changes in the lung as microscopic, well-differentiated squamous cell carcinomas and cystic keratinised squamous cell carcinomas. The total incidence of the squamous cell carcinomas was 2/75 in males and 3/75 in females. Squamous cell carcinomas were described as to be "so well-differentiated that it was extremely difficult to distinguish them from squamous cell metaplasia". In addition bronchioalveolar ademona were observed but were not associated with exposure to the test substance. Because similar lesions were observed in rat lungs after high-dose, chronic exposure to other particulates such as para-aramid fibrils, chromium dioxide, and titanium dioxide; it was suggested that this may be indicative of a normal, biological response. Accordingly, the lesions were subsequently re-examined by a panel of four pathologists (Frame and Stone 1995):

"Cystic keratinizing squamous lesions were produced in rats following chronic exposure to high concentrations of TiCl4 . These lesions were evaluated by four pathologists using recently proposed diagnostic criteria. Unanimous agreement was reached as to the diagnosis of each of the lesions. Three of the lesions were diagnosed as squamous metaplasia and two as pulmonary keratin cyst. Although the epithelial lining of some of these cysts had varying degrees of irregularity, most other criteria given for epithelioma were absent."

 

CONCLUSION:

Based on the results stated above a LOAEC of 0.1 mg/m³ for local reactions in the respiratory tract is derived for the rat after chronic exposure to fumes derived from the partial hydrolysis of TiCl4 in air.

Exposure to TiCl4 triggered the normal pulmonary foreign body defence and clearance mechanisms. These were overwhelmed at the 10.0 mg/m³ exposure concentration and resulted in an increased lung burden over the course of the study. A compensatory increase in phagocytic cell production was observed. Most of the TiCl4 solid hydrolysis products in the lung were phagocytized by alveolar macrophages, which aggregated at alveolar ducts and adjoining alveoli. Type II pneumocyte hyperplasia, alveolar bronchiolarisation, cholesterol granulomas, foamy alveolar macrophage infiltration, alveolar proteinosis and focal fibrotic pleurisy were associated with exposure to 10 mg/m³ TiCl4. Lesions in lungs of animals of this dose groups that were originally described as cystic keratinising squamous cell carcinomas were re-assessed as squamous cell metaplasia or pulmonary keratin cysts. Therefore TiCl4 is not carcinogenic up to the highest tested dose.

Endpoint conclusion
Endpoint conclusion:
adverse effect observed
Dose descriptor:
LOAEC
0.1 mg/m³
Study duration:
chronic
Species:
rat

Repeated dose toxicity: dermal - systemic effects

Endpoint conclusion
Endpoint conclusion:
no study available

Repeated dose toxicity: dermal - local effects

Endpoint conclusion
Endpoint conclusion:
no study available

Additional information

Oral and dermal:

Oral and dermal exposure of workers is only to be expected in case of accidents therefore the evaluation of repeated dose toxicity for these two routes of exposure is not necessary. Due to the reactivity of titanium tetrachloride with water the general public would only be exposed to titanium dioxide (TiO2) via the environment. TiO2 is a common mineral and an ingredient of several consumer products like toothpaste and sunscreen. Therefore the additional exposure of the general public towards TiO2 via the environment stemming from TiCl4 production and use is negligible.

Inhalation:

TiCl4 tested at atmosphere concentrations of 0.10, 1.0 and 10.0 mg/m3 was innocuous to the skin and mucosal surfaces of the eyes and nares.

The mode of action is the local irritation/corrosion by hydrochloric acid (HCl) formed in contact with water. Starting already at the lowest dose of 0.1 mg/m³ irritation to the conducting airways of the upper respiratory tract epithelium (rhinitis and tracheitis) was seen. The derivation of the LOAEC is based on these effects.

At higher concentrations of 1.0 and 10 mg/m³ the lung is the primary target organ for the dose- and time-dependent toxic effects which resulted from exposure to TiCl4. Due to increasing irritation by the action of HCl and deposition of TiO2 particles the clearance mechanisms of the lungs including increased phagocytosis get overwhelmed at the highest dose. Particle-laden phagocytic cells aggregated around the alveolar ducts and within adjoining alveoli, and at the highest dose cholesterol clefts, cholesterol granulomas and focal pleurisy were seen. Cystic keratinising squamous cell carcinomas, seen only at the highest dose, were associated with alveolar cell hyperplasia and squamous cell metaplasia and are associated to the deposition of TiCl4 hydrolysis products leading to particle overload. The carcinomas did not metastasize and had little tendency for microinvasion, therefore a panel of four pathologists conducting a re-examination concluded that these lesions are not carcinomas but squamous cell metaplasia or pulmonary keratin cysts. Therefore TiCl4 is not carcinogenic up to the highest tested dose.

Based on these findings the lowest concentration of 0.1 mg/m³ is deemed the Low Adverse Effect Concentration (LOAEC) for inhalation repeated dose toxicity stemming from local effects.

The No Observed Effect Concentration (NOAEC) for cholesterol granuloma formation and alveolar proteinosis was 1.0 mg/m3.

Repeated dose toxicity: inhalation - systemic effects (target organ) respiratory: other

Justification for classification or non-classification

Two year inhalation study in rat (vapour): the Low Adverse Effect Concentration (LOAEC) for inhalation repeated dose toxicity (stemming from local effects) was 0.1 mg/m³. As this effects are based on the irritation/corrosion at the portal of entry, a classification for target organ toxicity is not applicable