Dichlorobis(η-cyclopentadienyl)titanium

Acute Toxicity: oral

Administrative data

Endpoint:

acute toxicity: oral

Type of information:

experimental study

Adequacy of study:

key study

Study period:

The studies were published in 1985 and 1987 and included in this review in 1991.

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

comparable to guideline study with acceptable restrictions

Data source

Reference

Reference Type:

publication

Title:

Unnamed

Year:

1991

Materials and methods

Test guideline

Qualifier:

no guideline followed

Principles of method if other than guideline:

14-day study
Groups of 5 rats of each sex were administered 0, 62, 125, 250, 500, or 1,000 mg/kg titanocene dichloride in corn oil by gavage 5 days per week for a total of 12 dose days. Animals were weighed prior to study initiation, on days 7 and 14, and at the end of the study. Observations for signs of toxicity were made twice daily throughout the studies. Animals found moribund and those surviving to the end of the study were killed, and blood was collected for hematology and clinical chemistry analyses. A complete necropsy was performed on all animals, including those dying before the end of the study.

GLP compliance:

no

Test type:

standard acute method

Limit test:

no

Test material

Test material information

Constituent 1

Reference substance name:

Dichlorobis(η-cyclopentadienyl)titanium

EC Number:

215-035-9

EC Name:

Dichlorobis(η-cyclopentadienyl)titanium

Cas Number:

1271-19-8

Molecular formula:

C10H10Cl2Ti

IUPAC Name:

dicyclopenta-1,3-dien-1-yltitanium(2+) dichloride

Test material form:

solid: crystalline

Specific details on test material used for the study:

Titanocene dichloride was obtained in two lots. Lot no. PB013180 from Pfaltz and Bauer, Inc. (Waterbury, CT) was used for the 14-day and 13-week studies. Strem Chemicals (Newbury Port, MA) provided lot no. 13574-S,which was used for the 2-year studies. Identity, purity, and stability analyses were conducted at the analytical chemistry laboratory, Midwest Research Institute (MRI), Kansas City, MO. The study chemical, a dark red, microcrystalline solid, was identified as titanocene dichloride by infrared and nuclear magnetic resonance spectroscopy. Lot no.PB013180 was greater than 98% pure, as determined by titration and elemental analysis. The purity of lot no. 1357443 was determined to be greater than 99% by titration, elemental analysis, and Karl Fischer water analysis. Stability studies performed by titration indicated that titanocene dichloride was stable as a bulk chemical for at least 2 weeks at temperatures to 60°C when protected from light.
Based on the stability study results, the bulk chemical was stored at 0°C is 5°C at the testing laboratory throughout the study period. The stability of the bulk chemical was monitored by elemental analysis and by titration periodically during all phases of the studies. No change in the study material was detected.

Test animals

Species:

rat

Strain:

Fischer 344

Remarks:

F344/N

Sex:

male/female

Details on test animals or test system and environmental conditions:

14-day study

Animal Source
Charles River Breeding Laboratories, Inc., Kingston, NY

Time Held Before Study
6 or 8 days (male) 5 or 13 days (female)

Age when Placed on Study
7 week

Animals per Cage
5

Method of Animal Identification
Ear punch

Feed
NIH-07 open formula meal diet; (Zeigler Bros., Inc., Gardners, PA), available ad libitum

Maximum Storage Time for Feed
120 days after milling

Feeders
Stainless steel, gang style (Scientific Cages, Inc.,Bryan, TX), changed weekly; filled as needed

Water
Automatic watering system, (Edstrom Industries, Inc., Waterford, WI), ad libitum

Cages
Polycarbonate (Lab Products, Inc, Rochelle Park, NJ), changed twice weekly

Bedding
Aspen bed (American Co., Excelsior Baltimore, MD), changed twice weekly

Cage filters
Non-woven fiber (Snow Filtration, Cincinnati, OH)

Racks
Stainless steel (Lab Products, Inc., Ruchelle Park, NJ), changed once every two weeks

Animal Room Environment:
Temperature: 21.1°C-24.4°C
Humidity: 32%-78%
Light: fluorescent, 12 hours/day
Room air changes: 12-15 changes/hour

Administration / exposure

Route of administration:

oral: gavage

Vehicle:

corn oil

Details on oral exposure:

14-day study: 5 days/week for 12 dose days; sacrificed on day 17

Doses:

14-day study: 0, 62, 125, 250, 500, and 1,000 mg/kg

No. of animals per sex per dose:

14-day study: 5 males and 5 females per dose

Control animals:

yes

Details on study design:

Groups of 5 rats of each sex were administered 0, 62, 125, 250, 500, or 1,000 mg/kg titanocene dichloride in corn oil by gavage 5 days per week for a total of 12 dose days. Animals were housed five per cage. Water and feed were available ad libitum.
Animals were weighed prior to study initiation, on days 7 and 14, and at the end of the study. Observations for signs of toxicity were made twice daily throughout the studies. Animals found moribund and those surviving to the end of the study were killed, and blood was collected for hematology and clinical chemistry analyses. A complete necropsy was performed on all animals, including those dying before the end of the study. Brain, heart, right kidney, liver, lung, and thymus from all animals were weighed, as well as the right testis from all males. Portions of the heart, liver, lung, and spleen (frozen in liquid nitrogen and stored at -60°C) were taken for evaluation of tissue residues for titanium. Histopathologic examinations were performed on selected tissues and animals.

Necropsy
Complete necropsy performed on all animals. Organ weights obtained for brain, heart, right kidney, liver, lung, thymus, and right testis (males).

Histopathology
Histopathologic examinations were performed on animals dying early and on selected organs in animals at terminal sacrifice. Tissues examined microscopically included kidney, liver, stomach, and testes for males given 0 to 500 mg/kg, and kidney, liver, and stomach for females given 500 mg/kg. Control females had kidney and liver examined, and females given 250 mg/kg had kidneys examined.
Histological examinations were not performed for females given 62 or 125 mg/kg or for any animals given 1,000 mg/kg. The colon was also examined for males and females given 500 mg/kg.

Clinical Pathology
Hematology: hematocrit (automated and manual), hemoglobin, erythrocyte, leukocyte count and differential.

Clinical chemistry: blood urea nitrogen; serum creatinine, sodium, potassium, chloride, carbon dioxide, calcium, phosphorus, total protein, albumin, globulin, albumin/globulin ratio, total and direct bilirubin, cholesterol, alanine aminotransferase, aspartate aminotransferase, lactate dehydrogenase, ornithine carbamoyltransferase, sorbitol dehydrogenase, and pH.

Urinalysis: specific gravity and urine pH

Supplemental Studies
Sections of heart, liver, lungs, and spleen from control, 250 (males), and 500 mg/kg groups were evaluated for titanium residues.

Results and discussion

Effect levels

Key result

Sex:

male/female

Dose descriptor:

other: Doses that lead to mortality

Effect level:

>= 500 - <= 1 000 mg/kg bw

Based on:

test mat.

Mortality:

All rats in the 1,000 mg/kg dose group died by the ninth day of dosing. In addition, four of the five male and two of the five female rats receiving 500 mg/kg titanocene dichloride died before the end of the studies.

Clinical signs:

other: Clinical findings in all rats in the 500 and 1,000 mg/kg dose groups included ruffled fur and hunched posture. Many of these animals also had diarrhea, ataxic gait, and a red nasal discharge. All male rats given 125, 250, 500, or 1,000 mg/kg and all femal

Other findings:

Treatment-related decreases in absolute organ weights occurred for heart, kidney, lung, and thymus in male rats given 125 or 250 mg/kg titanocene dichloride, for liver in male rats given 250 mg/kg, and for heart and thymus in female rats given 125, 250, or 500 mg/kg. Female rats also showed a significant chemical-related decrease in relative thymus weights, but the ratios were significant only for the 250 mg/kg group. These changes in organ weights were related to the decreased final body weights in treated groups.
There were mild chemical related decreases in albumin, globulin, calcium, and total protein concentrations in male rats given 62, 125, or 250 mg/kg titanocene dichloride. Alanine aminotransferase (ALT) levels were significantly greater than the control for males given 62, 125, or 250 mg/kg.
Significant decreases were present in total protein levels of females given 125, 250, or 500 mg/kg and in globulin levels of female rats given 250 or 500 mg/kg. There were significant chemical-related increases in ALT levels of females given 125, 250, or 500 mg/kg, albumin/globulin ratios and direct bilirubin levels of females given 250 or 500 mg/kg, and total bilirubin levels of females given 500 mg/kg. Hematocrit, hemoglobin and erythrocyte count values were decreased in female rats in the 500 mg/kg group
Tissue samples from males given 0, 250, or 500 mg/kg and from females given 0 or 500 mg/kg were analyzed for titanium residues. The highest levels of titanium were found in the spleen and liver.
Lesions observed in treated animals included multifocal hepatocellular necrosis in two of the five males given 500 mg/kg titanocene dichloride, hepatocellular hypertrophy in all males and females given 500 mg/kg, and nephrosis (acute cortical tubule necrosis) in all rats given 500 mg/kg and in two of the five females, given 250 mg/kg. There was hyperplasia of the forestomach epithelium of most male rats given 62, 125, 250, or 500 mg/kg and in three of the five females from the 500 mg/kg group. The severity of the hyperplasia in males increased with dose. Erosions and ulcers of the glandular stomach were also present in most treated males and in females from the 500 mg/kg dose group, and were associated with acute inflammation and regenerative hyperplasia.

Any other information on results incl. tables

Survival and Mean Body Weights of Rats in the 14-Day Gavage Studies of Titanocene Dichloride

	Dose (mg/kg bw)	Survival^a	Mean Body Weights^b(g)			Final Weight Relative to Controls (%)
			Initial	Final	Change
Male	0	5/5	170 ± 4	220 ± 5	50 ± 2
	62	5/5	170 ± 7	222 ± 8	52 ± 2	101
	125	5/5	169 ± 4	206 ± 5	36 ± 2	93
	250	5/5	170 ± 4	187 ± 6**	17 ± 4**	85
	500	1/5^c	170 ± 3	107 ± 4**	69 ± 2**	48
	1000	0/5^d	170 ± 4	-	-	-
Female	0	5/5	94 ± 4	134 ± 5	40 ± 2
	62	5/5	93 ± 3	138 ± 3	45 ± 2	103
	125	5/5	94 ± 3	123 ± 5	29 ± 3*	91
	250	5/5	94 ± 2	117 ± 2*	24 ± 2**	87
	500	3/5^e	94 ± 2	84 ± 10**	-8 ± 8**	63
	1000	0/5^f	93 ± 2	-	-	-

* Significantly different (P≤0.05) from the control group by Dunn's or Shirley's test.

**P≤0.01

a Number surviving/number initially in group

b Mean ± standard error. Subsequent calculations are based on animals surviving to the end of the study.

c Day of death: 9, 9, 9, 16

d Day of death: 5, 7, 8, 8, 9; no data reported due to 100% mortality in this group

e Day of death: 13, 16

f Day of death: 4, 7, 7, 8, 9; no data reported due to 100% mortality in this group

Applicant's summary and conclusion

Interpretation of results:

Category 4 based on GHS criteria

Conclusions:

In the NTP 14-day studies, mortality occurred in both sexes of rats receiving the two highest doses (500 and 1,000 mg/kg). Animals that died were observed to have had diarrhea, ataxia, acute renal tubular necrosis, and a spectrum of degenerative lesions in the stomach. Although the precise cause of death was not determined, it is likely that the rats died from the renal lesions complicated by serum electrolyte changes or an acid-base imbalance, or both, resulting from the gastric lesions.
Based on this data the substance is classified in Category 4.

Executive summary:

Toxicology and carcinogenesis studies were conducted by administering titanocene dichloride (greater than 98% pure) in corn oil by gavage to groups of F344/N rats for 14 days.

In the 14-day studies, titanocene dichloride was administered at doses of 0, 65, 125, 250, 500, or 1,000 mg/kg. All high-dose rats and four of the five male and two of the five female rats given 500 mg/kg died during the studies. A dose-related decrease in body weight gain was seen in rats given 125, 250, 500, and 1,000 mg/kg. Lesions related to chemical administration included hepatocellular necrosis, tubule necrosis in the kidney, erosions and ulcers of the glandular stomach, and hyperplasia of the forestomach epithelium.