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Toxicological information

Repeated dose toxicity: oral

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Administrative data

Endpoint:
sub-chronic toxicity: oral
Type of information:
experimental study
Adequacy of study:
key study
Study period:
October 1965
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
guideline study with acceptable restrictions
Remarks:
Test method is similar to OECD guideline 408. No GLP study.

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
1965

Materials and methods

Test guideline
Qualifier:
equivalent or similar to
Guideline:
OECD Guideline 408 (Repeated Dose 90-Day Oral Toxicity in Rodents)
Deviations:
not specified
GLP compliance:
no
Limit test:
no

Test material

Reference
Name:
Unnamed
Type:
Constituent
Test material form:
solid: particulate/powder
Details on test material:
- Physical state: a blue powder
Specific details on test material used for the study:
Batch nº: A20 FT3

Test animals

Species:
rat
Strain:
Sprague-Dawley
Sex:
male/female
Details on test animals and environmental conditions:
TEST ANIMALS- Age at study initiation: 21 days- Weight at study initiation: 39-47 g- Housing: rats of the same sex were placed in pairs in individual galvanised wire mesh cage- Diet (e.g. ad libitum): oxoid breeding dietENVIRONMENTAL CONDITIONS- Temperature: 70±1ºF- Humidity (%): greater than 50%

Administration / exposure

Route of administration:
oral: feed
Vehicle:
unchanged (no vehicle)
Details on oral exposure:
-All drug diets were mixed in batches of 20 Kg at approximately 14 day intervals with unpelleted Oxoid breeding diet.
Analytical verification of doses or concentrations:
no
Duration of treatment / exposure:
91 days
Frequency of treatment:
Every day
Doses / concentrationsopen allclose all
Dose / conc.:
5 mg/kg bw/day (nominal)
Remarks:
approximately
Dose / conc.:
50 mg/kg bw/day (nominal)
Remarks:
approximately
Dose / conc.:
500 mg/kg bw/day (nominal)
Remarks:
approximately
Dose / conc.:
5 000 mg/kg bw/day (nominal)
Remarks:
approximately
No. of animals per sex per dose:
1 group of 20 male rats: 5 mg/kg bw / 1 group of 20 female rats: 5 mg/kg bw1 group of 20 male rats: 50 mg/kg bw / 1 group of 20 female rats: 50 mg/kg bw1 group of 20 male rats: 500 mg/kg bw / 1 group of 20 female rats: 500 mg/kg1 group of 20 male rats: 5000 mg/kg bw/ 1 group of 20 female rats: 5000 mg/kg bw
Control animals:
yes, plain diet

Examinations

Observations and examinations performed and frequency:
DETAILED CLINICAL OBSERVATIONS: Yes - Time schedule: - During the test period the rats were observed for any abnormal behaviour and obvious signs of ill health or untoward effects which could be atributed to feeding the test material.BODY WEIGHT: Yes- Time schedule for examinations: The animals were weighed weekly.FOOD CONSUMPTION AND COMPOUND INTAKE (if feeding study):-The food consumption was measured daily on 8 animals in each group. The test material intake as g/kg rat/day was calculated from the food consumption and body weight data.HAEMATOLOGY: Yes - Time schedule for collection of blood: Blood samples were taken for haematological examination at the start of the experiment, at monthly intervals during the treatment period and immediately before autopsyCLINICAL CHEMISTRY: Yes- Time schedule for collection of blood: -Blood samples were taken for biochemical analysis at the end of the treatment periodURINALYSIS: Yes - Time schedule for collection of urine: Urine samples were taken one week before the end of the treatment period.
Sacrifice and pathology:
GROSS PATHOLOGY: Yes HISTOPATHOLOGY: Yes At the end of the treatment period the rats were killed, examined pathologically, and the main organs removed, weighed and prepared for histological examination. Animals which died during the test were sent for post mortem examination. Samples of bone marrow were taken at post mortem and examined microscopically.
Statistics:
Analysis of variance.

Results and discussion

Results of examinations

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):
effects observed, treatment-related
Food efficiency:
not specified
Water consumption and compound intake (if drinking water study):
not specified
Ophthalmological findings:
not examined
Haematological findings:
no effects observed
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:
no effects observed
Histopathological findings: non-neoplastic:
no effects observed
Histopathological findings: neoplastic:
no effects observed
Details on results:
CLINICAL SIGNS AND MORTALITYOf the 17 animals which died during the treatment period, only 7 were suitable for post mortem due to autolytic changes. Two of the animals fed the diet containing 5000 mg/kg/day and 2 fed the diet containing 500 mg/kg/day were found to have inflammation of the bladder. BODY WEIGHT AND WEIGHT GAINAnalysis of variance was carried out on the data from each week of the test, as also was Rao´s analysis using time intervals of 1 day. A Rao´s analysis using a 7 day interval was carried out at the end of the test. As the rats were places in metabolism cages during the 12th week of the test, the growth weights were only taken for analysis up to the end of the 11th week of the test. In comparison with the controls, growth was depressed in the high dosage group (5000 mg/kg/day) in both the males and the females, beginning at the end of the first week of the test. In the other dosage groups, the male rats if anything grew rather better than the controls but the differences were not significant. The growth rates of the female rats in all these groups were the same as the controls. FOOD CONSUMPTION AND COMPOUND INTAKE (if feeding study)The food consumption figures for the males do not account for the difference in growth rate between the control and the 5000 mg/kg/day and 500 mg/kg/day dose level groups. In the first 5 weeks the food consumption of the 5000 mg/kg/day group was less than all the other groups, and this accompanied by the fact that 10 of the intake had no nutritive value could well account for the decrese in growth. Towards the end of the test period the intake of the rats at this dose level was approximately the same as that of the other groups. The food consumption figures for the females show an increase in food consumption of the 5 mg/kg/day dose level group and a decrease of the 5000 mg/kg/day over the controls during the first half of the test. This could account for the differences in observed growth rates. HAEMATOLOGY-Haemoglobin: the only significant findings were in the highest dosage group ( 5000 mg/kg/day) where in both the males and the females there was a slight but significant depression.-Red cell count: no significant effects were observed at any dose level. - Packed cell volume: in the males a highly significant decrease was observed at the 5000 mg/kg/day dose level at the end of the test period. A similar decrease was observed in the females at this dose level but it was not statistically significant. - Mean corpuscular volume: at the end of the test period a significant decrease was observed in the males at the 5000 mg/kg/day dose level. - Mean corpuscular haemoglobin: at the end of the test period a significant decrease was observed in the males at the 5000 mg/kg/day dose level. - Mean corpuscular haemoglobin concentration: no differences of significance were observed. - Reticulocyte counts: a very significant increase was observed in the males and a significant increase in the females at the 5000 mg/kg/day dose level. - Total leucocyte count: an increase was observed at the 5000 mg/kg/day dose level in the females in the 4th, 8th and 12th weeks. - Differential cell count: Neutrophils: a highly significant increase occurred in the males at the 5000 mg/kg/day dose level in the 4th and 8th weeks but no differences were observed at the end of the test period.Lymphocytes: a highly significant difference was observed in the males in the 8th week at the 5000 mg/kg/day dose level.Eosinophils: no differences of significance were observed.Basophils: no differences were observed.Monocytes: no differences of significance were observed. CLINICAL CHEMISTRY- Blood urea: consistent results were obtained in the controls and all the treatment groups. A small but significant increase of the blood urea in the males on the higher dose level was not confirmed in the females. It is concluded that the test substance has no significant influence on the level of urea in the blood.- Blood reducing sugar as glucose: The means were consistent in all treatment groups and there were no real differences between levels in the treated and control rats. It it concluded therefore that the chronic treatment of rats with the test substance does not affect the blood sugar levels. - Serum inorganic phosphorus: the results were consistent in all groups. There was a slight but significant rise in this constituent at the highest dose level both in the males and females. - Serum cholesterol: while the values were consistently higher in the females than the males there were no differences in the group values between the treated and control rats in either sex. - Serum silica: there was not evidence that feeding of the test substance had any influence on the serum silica levels. - Serum alkaline phosphatase: while the values were lower in females than in the males there were not significant differences between the controls and the treated groups in either sex. - Serum transaminase: while the values were higher in the treated groups than in the controls the differences were small and of low significance. - Serum protein and serum albumin: administration of the test substance had no influence on the serum protein and serum albumin levels. - Serum sodium and serum potassium: there were no significant differences between the treated and control groups at all dosage levels. URINALYSIS- Urine volume: there was a highly significant increase in the males and a significant increase in the females at the top dosage group. - Sodium excretion: there was a highly significant increase in sodium excretion in both the males and females at the top dosage groups. - Potassium excretion: there was no significant effect on urinary potassium excretion at any dose level.- Creatinine excretion: there was no significant difference between the treated and controls rats.- Silica excretion: the levels of silica excreted in the urine were increased very significantly when feeding the test substance to rats and the increase was related to the dose. - Qualitative tests: examination of the urines for sugars and ketones showed no difference between the control and treated groups. Deposits of siliceous material were found in the urine of a few of the animals at the two highest dose levels. ORGAN WEIGHTSNo significant differences were observed in the following organs: adrenals, brain, gonads (ovaries, prostate and uterus), heart, pituitary, thymus, thyroid. - Gonad - Testes: At the 50 mg/kg/day dose level there was a significant increase in the actual weight as compared with the controls but these were not significant when the weights were expressed as a percentage of body weight. - Kidneys: in the males there was a highly significant increase in the actual weight at the 5 mg/kg/day dose level when compared with the controls but the difference was not significant when the weights were expressed as a percentage of the body weight. In the females a significant decrease in the actual weights was observed at the 50 mg/kg/day, 500 mg/kg/day and 5000 mg/kg/day dose levels but no difference or significance were observed when the weights were expressed as a percentage of the body weight. - Liver: a significant increase in actual weight of the males and females was observed at the 5000 mg/kg/day dose level. These increases persisted when the weights were expressed as a percentage body weight. - Lungs: in the females a significant increase in the actual weight was observed at the 5 and 50 mg/kg/day dose levels and at the 5000 mg/kg/day dose level. These increases in weight still persisted when the weights were expressed as a percentage body weight. In the males a similar pattern was observed but the differences were not significant.- Spleen: a very highly signficant increase in actual weights was observed in the males at the 5000 mg/kg/day dose level. This increase was accentuated when the weights were expressed as a percentage of the body weight. A similar pattern was observed in the females but the differences were not significant. HISTOPATHOLOGY: NON-NEOPLASTIC- Bone marrow smears of animals from both the control and treated groups showed no significant differences. There were about an equivalent number of animals showing an increase in erythroid cells and in total eosinophil cells in all groups. No pathological changes were observed at any dose level in any of the following: adrenals, brain, eye, uterus, pancreas, parathyroid, skin, thymus (males), thyroid (females). - Bladder: inflammation of the bladder wall was observed at the 50, 500 and 5000 mg/kg/day dose levels, the incidence increasing with the dose. This was associated with the presence of small siliceous stones and deposits particularly at the high dose level. - Colon: inflammation of the mucosa was a common finding in all groups including the controls. This could in part be accounted for by the nature of the compound administered and also to a worm infestation seen in the controls. - Gonads: The incidence of these effects was of no significance. Ovaries: one of the females on the 500 mg/kg/day dosage level showed interstitial inflammation. Testes: one of the control group showed atrophy and two at the 5000 mg/kg/day dosage level showed a depression of spermatogenesis. Prostate: inflammation occurred in four of the controls, in 2 at the 5 mg/kg/day and 2 at the 5000 mg/kg/day dosage level groups. - Heart: one of the males on the 50 mg/kg/day dosage level and two of the females on the 5000 mg/kg/day showed a slight myocarditis. This was most likely due to an infection. - Kidney: pyelonephritis was a common finding and occurred at all dosage levels and also in the controls. This is a common finding in laboratoy rats and is possibly due to a virus infection. It is not therefore regarded as being primarily due to the treatment of the rats with the test substance although there was evidence that it did increase in severity particularly at the high dose level. - Liver: all the sections showed some glycogen depletion together with a slight fatty infiltration. This occurred in the controls as well as in the treated groups and was probably due to deprivation of food overnight before the rats were killed. - Lung: sections of the lungs from the controls as well as the treated groups showed evidence of pneumonitis. This has been a constant finding in our rats and is no doubt due to an inherent infection. - Lymph node: sinus catarrh was found in one female on the 5 mg/kg/day dose level and in one male on the 50 mg/kg/day and one on the 5000 mg/kg/day dose level. These observations are of no significance. - Pituitary: grannulation of the thyrotrophs was observed in one male in the control group and one on the 500 mg/kg/day dose level.- Small intestine: slight inflammation of the mucosa was a common finding at all dose levels including the controls. The effects were not severe and are to be expected from feeding this foreign material.- Spleen: an increase in brown pigmented macrophages was observed in a male on the 50 mg/kg/day dose level, in a control female and in 4 females on the 500 mg/kg/day dose level. Vascular sclerosis was observed in a male in the 500 mg/kg/day dose level. This was of no significance.- Stomach: inflammation of the mucosa was observed particularly at the highest dosage level. This is to be expected following administration of this foreign material. - Thyroid: in the males diffuse hyperplasia was observed in one on the 5, one on the 50 and two on the 500 mg/kg/day dose levels and in one of the females on the 50 mg/kg/day dose level. - Thymus: two of the females on the 5000 mg/kg/day dose level showed hyperplasia. The incidence is of no significance. - Tongue: one of the control females showed arteriolar sclerosis.

Effect levels

Key result
Dose descriptor:
NOAEL
Effect level:
>= 50 mg/kg bw/day (nominal)
Based on:
test mat.
Sex:
male/female
Basis for effect level:
mortality

Target system / organ toxicity

Critical effects observed:
not specified

Applicant's summary and conclusion

Conclusions:
The NOAEL is considered to be 50 mg/kg bw/day.
Executive summary:

The aim of the study was to assess the subchronic oral toxicity of the test material following a repeted dose oral administration of the test material mixed in the diet at four dose levels (5, 50, 500, 5000 mg/kg bw) to groups of 20 male and female rats (a total of 200) during 91 days. The test procedure used was equivalent to the OECD guideline 408. The NOAEL is considered to be 50 mg/kg bw/day.