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Repeated dose toxicity: oral

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Administrative data

sub-chronic toxicity: oral
Type of information:
experimental study
Adequacy of study:
key study
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: see 'Remark'
Study conduct prior to guideline and GLP implementation, however study is well documented and complies to a large extent to the later implemented guideline OECD 408 and GLP requirements. No information on the homogeneity or stability of the test substance in the diet was provided.

Data source

Reference Type:
study report
Report date:

Materials and methods

Test guideline
equivalent or similar to guideline
OECD Guideline 408 (Repeated Dose 90-Day Oral Toxicity Study in Rodents)
some limitations
GLP compliance:
Limit test:

Test material

Constituent 1
Reference substance name:
Dioctyltin bis(2-EHMA) [CAS No. 15571-58-1]:Octyltin tris(2-EHMA) [CAS No. 27107-89-7] + Trioctyltin (2-EHMA) [CAS No. 61912-55-8] (97.0:0.3:2.17% mixture)
Dioctyltin bis(2-EHMA) [CAS No. 15571-58-1]:Octyltin tris(2-EHMA) [CAS No. 27107-89-7] + Trioctyltin (2-EHMA) [CAS No. 61912-55-8] (97.0:0.3:2.17% mixture)
Details on test material:
Dioctyltin bis(2-EHMA) [CAS No. 15571-58-1]:Octyltin tris(2-EHMA) [CAS No. 27107-89-7] + Trioctyltin (2-EHMA) [CAS No. 61912-55-8] (97.0:0.3:2.17% mixture)

Test animals

Details on test animals or test system and environmental conditions:
- Source:no data
- Age at study initiation:no data
- Weight at study initiation:no data
- Fasting period before study:no data
- Housing: Test animals were housed in groups of 5
- Diet (e.g. ad libitum): not precised, ad libitum
- Water (e.g. ad libitum): not precised, ad libitum
- Acclimation period:no data

- Temperature (°C):24
- Humidity (%):no data
- Air changes (per hr):no data
- Photoperiod (hrs dark / hrs light):no data

Administration / exposure

Route of administration:
oral: feed
unchanged (no vehicle)
Details on oral exposure:
In the first experiment, groups of 30 weanling Wistar rats (CIVO-colony) (15 rats/sex/group) were exposed to the test substance, administered in the diet, at dose levels of 0, 100, 500, and 1000 ppm. Due to excessive mortality at 1000 ppm, a second experiment was initiated.
Groups of rats (15 per sex) were exposed to dose levels of 0, 50, and 250 ppm test substance in the diet. In a third experiment, groups of rats were exposed to 10 and 25 ppm of the test substance in the diet.

The test diets were prepared every two weeks and stored at room temperature. The test substance was thoroughly mixed in the stock diet.
Analytical verification of doses or concentrations:
Duration of treatment / exposure:
90 days
Frequency of treatment:
Doses / concentrationsopen allclose all
Doses / Concentrations:
100, 500, and 1000 ppm (experiment 1)
nominal in diet
Doses / Concentrations:
50 and 250 ppm (experiment 2)
nominal in diet
Doses / Concentrations:
10 and 25 ppm (experiment 3)
nominal in diet
No. of animals per sex per dose:
15 rats/sex/group (experiment 1,2 and 3)
Control animals:
yes, concurrent no treatment
Details on study design:
Positive control:


Observations and examinations performed and frequency:
Body weights were recorded weekly. Food intake (by group) was determined during the exposure period. Food efficiency was calculated over the first four weeks of exposure. Water consumption (by group) was determined during the first week of exposure. Blood samples were collected in weeks 6 and 12.

Hematological data included hemoglobin content, packed cell volume, red blood cell counts, and total and differential white blood cell counts. Biochemical data collected terminally included blood sugar, blood urea nitrogen (BUN), serum glutamic-pyruvic transaminase (SGPT), serum glutamic oxaloacetic transaminase (SGOT), serum alkaline phosphatase (SAP), and total serum protein (TSP).
Kidney function was examined by determining glutamic oxaloacetic transaminase (UGOT) in the urine and urine protein.
Urine samples were collected, pooled by treatment level, and examined for appearance, pH, glucose, albumin, occult blood, ketones, and microscopy of the sediment.

Sacrifice and pathology:
At the end of the experimental period, animals were sacrificed and examined macroscopically for pathological changes. In the first experiment, the water content of the brain was determined in 10 rats (5 per sex) from each treatment group. In the second experiment, the tin content of pooled samples of the liver, kidneys, and testicles of 10 rats of each treatment group was determined.

Detailed microscopic examination of organs and tissues in the first experiment (control and 500 ppm groups) included: lungs, trachea, pancreas, salivary glands (parotid, submaxillary, and sublingual), prostate, epididymis, uterus, coagulating gland, seminal vesicle, thoracic aorta, stomach, duodenum, ileum, cecum, colon, mesenteric and axillary lymph nodes, urinary bladder, skeletal muscle, spinal cord, femoral nerve, sternum with marrow, exorbital lachrymal glad, preputial gland, and skin. Microscopic examination of rats in the 100 ppm group was limited to the liver, kidneys, spleen, thymus, lymph nodes, heart, and testicles. Animals that died before the end of the exposure period were not examined pathologically.
In the second experiment, microscopic examinations of all groups were limited to the liver, kidney, spleen, thymus, and lymph nodes.
Other examinations:
no data

Results and discussion

Results of examinations

Clinical signs:
effects observed, treatment-related
mortality observed, treatment-related
Body weight and weight changes:
effects observed, treatment-related
Food consumption and compound intake (if feeding study):
effects observed, treatment-related
Food efficiency:
not specified
Water consumption and compound intake (if drinking water study):
no effects observed
Ophthalmological findings:
not examined
Haematological findings:
effects observed, treatment-related
Clinical biochemistry findings:
effects observed, treatment-related
Urinalysis findings:
effects observed, treatment-related
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:
no effects observed
Details on results:
Mortality occurred at 250, 500, and 1000 ppm.

Mean body weights and food intake were reduced at 250, 500, and 1000 ppm.

Hemoglobin content and white blood cell counts were slightly decreased at 250 and 500 ppm. There was a considerable increase in the number of neutrophils and leukocytes, and a decrease in the number of lymphocytes at >=100 ppm.

There were minimal to moderate changes in the microscopic findings in urine. Specific gravity of the urine was decreased and UGOT levels were increased at 500 ppm. Specific gravity of the urine of females at 100 ppm was decreased. SAP levels were significantly increased at >=100 ppm. Glucose levels were decreased at 500 ppm and BUN levels were increased in males at 500 ppm. SGPT levels for males and females were increased at 500 and 100 ppm, respectively.

There was no increase in water content of the brain. Relative liver and kidney weights were slightly increased at >=100 ppm. Relative thymus weights were reduced at >=25 ppm. The relative weights of the heart (females), brain (both sexes), and gonads (males) were significantly increased at 500 ppm. The increase in relative weight of the liver was not dose-dependent. The relative weights of the brain and the testicle showed an inverse relationship with body weights. The relative spleen weight was slightly increased in some dose groups. Treatment-related gross pathological changes observed included a reduction in thymus size at >=100 ppm. The number of lymphocytes in the
thymus were depleted at >=100 ppm.

Other changes observed included signs of chronic respiratory disease, unilateral hydronephrosis, and proteinaceous plugs in the urinary bladder; however, the latter are commonly found in the strain of rats tested and, therefore, may not be related to exposure to the test substance. Treatment-related histological lesions in the liver and kidneys ranged from minimal (250 ppm) to moderate (500 and 1000 ppm).

The no-observable-adverse-effect-level (NOAEL) was determined to be 10 ppm in the diet (equivalent to 0.5 mg/kg/bw/day) of rats exposed for 90 days, on the basis of reduced thymus weight at 25 ppm. Based on these findings, the lowest-observable-adverse-effect level (LOAEL) was determined to be 25 ppm in the diet (calculated as 1.07-1.24 mg/kg bw/day in males and 1.46-1.51 mg/kg bw/day in females). Calculation of dosage was performed using body weights of 0.34 kg (males) and 0.2 kg (females), and average food consumption of 14.6-16.8 g/rat/day (males) and 11.7-12.1 g/rat/day (females).

Effect levels

Dose descriptor:
Effect level:
10 ppm
Based on:
test mat.
Basis for effect level:
other: reduced thymus weight (10 ppm is equivalent to 0.5 mg/kg/bw/day)

Target system / organ toxicity

Critical effects observed:
not specified

Applicant's summary and conclusion

The NOAEL for DOT(2-EHMA) was determined to be 10 ppm (equivalent to 0.5 mg/kg bw/day) based on reduced thymus weight.
Executive summary:

A repeated dose oral toxicity study was carried out with rats and a mixture of Dioctyltin bis(2-EHMA) [CAS No. 15571-58-1]:Octyltin tris(2-EHMA) [CAS No. 27107-89-7]: Trioctyltin (2-EHMA) [CAS No. 61912-55-8] (97.0:0.3:2.17% mixture). The study predates GLP, but is well documented and quality assurance is comparable. No information on the homogeneity or stability of the test substance in the diet was provided, due to which the study was considered less reliable. The NOAEL was determined to be 10 ppm (equivalent to 0.5 mg/kg bw/day) and the LOAEL was determined to be 25 ppm (equivalent to 1.3 mg/kg bw/day) based on reduced thymus weight.