Repeated dose toxicity: oral.001

Repeated dose toxicity: oral.001

Administrative data

Study result type:

experimental result

Study period:

No data

Reliability:

4 (not assignable)

Rationale for reliability incl. deficiencies:

Lack of details concerning results

Data source

Referenceopen allclose all

Reference 1

Reference Type:

publication

Title:

Toxicity of chlorine dioxide in drinking water

Author:

Abdel-Rahman MS, Couri D, Bull RJ

Year:

1985

Bibliographic source:

J. Environ. Pathol. Toxicol. Oncol, 6: 105-113

Reference 2

Reference Type:

publication

Title:

Toxicity of chlorine dioxide in drinking water

Author:

Abdel-Rahman MS, Couri D and Bull RJ

Year:

1984

Bibliographic source:

Journal of the American College of Toxicology, 3(4): 277-284

Materials and methods

Test guideline

Qualifier:

no guideline followed

Principles of method if other than guideline:

Studies were conducted to provide information on the effect of Cl compounds on the osmotic fragility of the red blood cells, blood glutathione, and blood cell compartment in rat after chronic treatment. In addition, the effect of Cl compounds on the incorporation of 3H-thymidine into nuclei of rat liver, kidney, small intestine, and testes was studied.

GLP compliance:

no

Test type:

chronic

Limit test:

no

Test materials

Identity of test material same as for substance defined in section 1 (if not read-across):

yes

Test material identityopen allclose all

Test material identity 1

Identifier:

CAS number

Identity:

10049-04-4

Test material identity 2

Identifier:

EC number

Identity:

233-162-8

Details on test material:

No data

Test animals

Species:

rat

Strain:

Sprague-Dawley

Sex:

male

Details on test animals and environmental conditions:

TEST ANIMALS
- Source: no data
- Age at study initiation: no data
- Weight at study initiation: 150-170 g
- Fasting period before study: no data
- Housing: no data
- Diet: ad libitum
- Water (e.g. ad libitum): no data
- Acclimation period: no data

ENVIRONMENTAL CONDITIONS
- Temperature: 22-23 °C
- Humidity: 55 %
- Air changes: no data
- Photoperiod: 12 hrs dark / 12 hrs light

IN-LIFE DATES: no data

Administration / exposure

Route of administration:

oral: drinking water

Vehicle:

water

Remarks:

double-distilled

Details on oral exposure:

No data

Analytical verification of doses or concentrations:

yes

Details on analytical verification of doses or concentrations:

ClO2 was generated daily and its concentration determined by diethyl-p-phenylene diamine.

Duration of treatment / exposure:

One year

Frequency of treatment:

20 hours/day, 7 days/weeks

Doses / concentrations

Doses / concentrations:

0, 1, 10, 100, 1000 mg/L

Basis:

nominal in water

No. of animals per sex per dose:

No data

Control animals:

yes, concurrent vehicle

Details on study design:

No data

Positive control:

No data

Examinations

Observations and examinations performed and frequency:

CAGE SIDE OBSERVATIONS: No data

DETAILED CLINICAL OBSERVATIONS: No data

BODY WEIGHT: Yes
- Time schedule for examinations: bimonthly

WATER CONSUMPTION AND COMPOUND INTAKE (if drinking water study): Yes
- Time schedule for examinations: daily

OPHTHALMOSCOPIC EXAMINATION: No

HAEMATOLOGY: Yes
- Time schedule for collection of blood: after 2, 4, 6, 7 and 9 months
- Anaesthetic used for blood collection: No data
- Animals fasted: No data
- How many animals: no data
- Parameters examined: osmotic fragility, red blood cell count, haemoglobin %, hematocrit %, mean corpuscular volume, mean corpuscular haemoglobin, mean corpuscular haemoglobin concentration.

CLINICAL CHEMISTRY: Yes
- Time schedule for collection of blood: after 2, 4, 7 and 9 months
- Animals fasted: No data
- How many animals: no data
- Parameters examined: whole blood glutathione

URINALYSIS: No

NEUROBEHAVIOURAL EXAMINATION: No

OTHER: 3H-Thymidine incorporation in organs of rats was evaluated.
Animals were administered i.p. 0.5 µCi/g bw of methyl, 1’,3’-3H-thymidine (128 Ci/mmol) after 3 months treatment with 10 and 100 mg/L ClO2 in daily drinking water. An 8 hour labeling period was used in all animals, since the number of labeled mitoses reaches a peak at 6-8 hours in small intestine. Rats were sacrificed by decapitation, and nuclei of liver, kidney, testes, and mucosa of small intestine were prepared as follows. Organs were removed quickly, rinsed twice in a beaker of ice cold saline, gently blotted dry with gauze, and weighed. The liver, kidney, and testes were minced into fine pieces with scissors, while small intestinal mucosa was obtained by scraping the epithelial layer with a scalpel blade. The minced pieces and mucosa were homogenized and centrifuged. The pellet was resuspended in STM buffer and centrifuged again. The supernatant was discarded and the pellet taken up in STM buffer. This fraction was designated “nuclei”.
Trichloroacetic acid was added to nuclei sample obtained for each organ. Samples were mixed and centrifuged. After the final centrifugation, DNA was trapped on a filter. Radioactivity was determined in a liquid scintillation spectrometer.

Sacrifice and pathology:

No data

Other examinations:

No data

Statistics:

No data

Results and discussion

Results of examinations

Clinical signs and mortality:

no effects

Body weight and weight gain:

yes

Remarks:

after 10 months

Food consumption and compound intake (if feeding study):

not examined

Food efficiency:

not examined

Water consumption and compound intake (if drinking water study):

no data

Ophthalmoscopic examination:

not examined

Haematology:

yes

Remarks:

depressed red blood cell counts, hemoglobin concentration, an packed cell volumes

Clinical chemistry:

yes

Remarks:

decrease in blood glutathione

Urinalysis:

not examined

Neurobehaviour:

not examined

Organ weights:

not examined

Gross pathology:

not examined

Histopathology: non-neoplastic:

not examined

Histopathology: neoplastic:

not examined

Details on results:

BODY WEIGHT AND WEIGHT GAIN
After 10 and 11 months, all treatment groups had significantly decreased body weight.

HAEMATOLOGY
Blood cell compartment results at 2, 4 and 6 months showed no significant changes in treated rats compared to control in red blood cell count, hemoglobin %, hematocrit %, mean corpuscular volume, mean corpuscular hemoglobin, and mean corpuscular hemoglocin concentration. However, after 7 months treatment the red blood cell counts were significantly increased in the 100 mg/L ClO2 group. Hematocrit was increased in 1000 and 100 mg/L ClO2 treatment groups. The mean corpuscular haemoglobin concentration was increased in 10 mg/L ClO2 group. After 9 months the red blood cell counts were decreased in all treatment groups; however, significant differences from control values were observed only in 1000 and 1 mg/L ClO2 treatment groups. The hematocrit % and haemoglobin % were significantly decreased in all treatment groups, while the mean corpuscular haemoglobin concentration was increased significantly in 1000 and 100 mg/L ClO2 groups only.

CLINICAL CHEMISTRY (glutathione)
At 2 months, the glutathione content decreased significantly in all groups, except the 100 mg/L ClO2 group. At 4 months, gluthatione content decreased only in 10 and 1 mg/L ClO2 groups. At 9 months the 100 mg/L ClO2 group was significantly increased.

OTHER FINDINGS
Decreased osmotic fragility was observed in all groups after 2, 3, 7 and 9 months of treatment.
The incorporation in kidney decreased significantly in the 100 mg/L ClO2 group only. The results in testes reveal that ClO2 diminished the incorporation of 3H-thyminidne in all groups. In intestinal mucosa, about a 2-fold increase of thymidine incorporation was observed in the 10 mg/L ClO2 group. While about a 50% of increase in incorporation occurred in the 100 mg/L ClO2 group.

Any other information on results incl. tables:

No data

Applicant's summary and conclusion

Executive summary:

In a chronic toxicity study, Chlorine Dioxide (ClO2) was administered to male Sprague-Dawley rats in drinking water at dose levels of 0, 1, 10, 100 and 1000 mg/L, 20 hour daily, 7 days per weeks, for one year.

Body weight was recorded bimonthly and water consumption daily. Animals were observed for haematology at 2, 4, 7 and 9th month and for clinical chemistry.

A significant decrease in body weight was observed in the 100 mg/L treated group, which persisted throughout treatment. After 10 and 11 months of exposure, all treatment groups had significantly decreased body weight.

In the study several hematological parameters were significantly altered in exposed rats, relative to controls, and included decreased osmotic fragility in the 10 and 100 mg/kg/day groups after 2, 4, 7, or 9 months of exposure, and in the 1 mg/kg/day group after 9 months of exposure; decreased erythrocyte counts in the 0.1 mg/kg/day and 100 mg/kg/day groups after 9 months of exposure, but not after 7 months; reduced hematocrit and hemoglobin levels in all groups at 9 months that did not exhibit clear dose-response patterns; increased hematocrit levels in the 10 and 100 mg/kg/day groups at 7 months; and increased mean corpuscular hemoglobin concentrations in the 10 and 100 mg/kg/day groups after 9 months. The study authors suggested that the decreased osmotic fragility may have been related to the disulfide bond between hemoglobin and the cell membrane as the result of oxidative stress.

3H-thymidine incorporation studies showed that ClO2 diminished DNA synthesis in testes, kidney and liver whereas increased DNA synthesis in intestinal mucosa was observed. Moreover, glutathione content decreased significantly in all groups, except the 100 mg/L ClO2 group. The reduction in DNA synthesis in liver and testes observed in this study may be related to the depression in overall protein synthesis caused by a reduction of glutathione content. On the other hand, the enhancement of DNA synthesis in small intestine may be explained by the direct effect of ClO2 treatment on the mucosa of small intestine (site of administration).