1,2-benzisothiazol-3(2H)-one

Repeated dose toxicity: oral

Administrative data

Endpoint:

sub-chronic toxicity: oral

Type of information:

experimental study

Adequacy of study:

key study

Study period:

1991

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

1991

Materials and methods

Test guideline

Qualifier:

according to guideline

Guideline:

EPA OPP 82-1 (90-Day Oral Toxicity)

GLP compliance:

yes

Test material

Test material information

Constituent 1

Reference substance name:

1,2-benzisothiazol-3(2H)-one

EC Number:

220-120-9

EC Name:

1,2-benzisothiazol-3(2H)-one

Cas Number:

2634-33-5

Molecular formula:

C7H5NOS

IUPAC Name:

1,2-benzisothiazol-3(2H)-one

Test material form:

solid

Specific details on test material used for the study:

Proxel Press Paste
The Test Substance employed was pre-dried technical grade active substance.
Purity: 93.3%
Batch number: BX 228

Test animals

Species:

rat

Strain:

other: Alpk:AfSD

Sex:

male/female

Details on test animals or test system and environmental conditions:

Age/Weight: 6-7 weeks old/males 152 to 230 g, females 133 to 170 g

Administration / exposure

Route of administration:

oral: feed

Vehicle:

other: feed

Analytical verification of doses or concentrations:

yes

Duration of treatment / exposure:

90 days

Frequency of treatment:

Daily, food consumption was recorded

Doses / concentrations

Doses / concentrations 1

Dose / conc.:

200 ppm

Doses / concentrations 2

Dose / conc.:

900 ppm

Doses / concentrations 3

Dose / conc.:

4 000 ppm

No. of animals per sex per dose:

12

Control animals:

yes, concurrent vehicle

Details on study design:

Post-exposure period: Not applicable

Results and discussion

Results of examinations

Clinical signs:

no effects observed

Mortality:

no mortality observed

Body weight and weight changes:

effects observed, treatment-related

Food consumption and compound intake (if feeding study):

effects observed, treatment-related

Ophthalmological findings:

no effects observed

Haematological findings:

no effects observed

Clinical biochemistry findings:

no effects observed

Urinalysis findings:

not examined

Organ weight findings including organ / body weight ratios:

no effects observed

Gross pathological findings:

effects observed, treatment-related

Histopathological findings: non-neoplastic:

effects observed, treatment-related

Details on results:

The bodyweights of animals given 4000 ppm were statistically significantly reduced throughout the study, such that the final bodyweights of males and females given 4000 ppm were 6% lower than their respective control values after adjustment for initial bodyweight (this is a statistically significant difference from the control group mean at the 1% level, Student’s t-test, two-sided).
The overall reduction in food utilisation apparent in males (statistically significant at the 1% level when compared to the control group mean) and to lesser extent females (not statistically significant) given 4000 ppm was due to the reduced food utilisation apparent during the first 4 weeks of the study.
The only macroscopic finding attributed to treatment with PROXEL Press Paste was a thickened limiting ridge in the stomach which was present in ten males and ten females given 4000 ppm and one male and one female given 900 ppm.

Effect levels

Key result

Dose descriptor:

NOAEL

Effect level:

69 mg/kg bw/day (nominal)

Based on:

test mat.

Sex:

male/female

Basis for effect level:

body weight and weight gain

food consumption and compound intake

Target system / organ toxicity

Key result

Critical effects observed:

no

Applicant's summary and conclusion

Conclusions:

Materials and methods
Groups of twelve male and twelve female Alpk:APfSD rats were fed diets containing 0, 200, 900 or 4000 ppm PROXEL Press Paste for a period of 90 days. At the start of study the animals were six to seven weeks old, the males were in the range 152 to 230g and the females weighed 133 to 170g. During the acclimatisation period (three weeks), the rats were randomly allocated into groups of four (sexes housed separately), using a procedure which ensured that all animals were equally represented in each groups. The Food consumption and bodyweight were monitored throughout the study and the average dose received by the animals in the 200, 900 and 4000 ppm groups was calculated as 15.3, 69.0 and 322.0 mg/kg/day for males, and 17.6, 78.3 and 356.3 mg/kg/day for females, respectively. The animals were examined prior to the start of the study to ensure that they were physically normal and exhibited normal activity. During the study the rats were observed daily for changes in clinical conditions and behaviour and once weekly a detailed examination of each rat was performed. An ophthalmoscopic examination of all animals in the control and 4000 ppm was performed prior to the start of the study and then during the week prior to termination. After 90 days of treatment all surviving animals were sacrificed and blood samples taken for haematological and clinical biochemistry examination. A full macroscopic examination was performed on all animals and the adrenal glands, kidneys, liver, brain and testes were weighed. Microscopic examination was performed on liver, kidney, lung and stomach samples from all animals and on all processed tissues from the control and 4000 ppm dose group.

Results and discussion
There were no mortalities, all animals were observed to be in good clinical condition and any clinical signs recorded were considered to be of a type and incidence commonly seen in rats of this age and strain and therefore not considered to be compound related.
The bodyweights of animals given 4000 ppm were statistically significantly reduced throughout the study, such that the final bodyweights of males and females given 4000 ppm were 6% lower than their respective control values after adjustment for initial bodyweight (this is a statistically significant difference from the control group mean at the 1% level, Student’s t-test, two-sided). There was evidence of a marginal difference in the growth of males given 900ppm, such that the final bodyweights after adjustment for initial weight were 3% lower than the control value. This difference was not statistically significant and considered to be too small to be toxicologically significant. There was no effect on bodyweight at any other dose level.
There was some evidence for a reduction in food consumption in females at 4000 ppm and in all male treatment groups. However, the differences from the control values in all male groups were small and were neither consistent nor dose-related; these differences were therefore considered not to be directly compound-related. There was an overall reduction in food utilisation apparent in males and females (not statistically significant in females) from the 4000 ppm dose group; this was considered to be a result of the reduced food utilisation observed during the first four weeks of dosing.
The eyes of most rats examined were normal and the small numbers of abnormalities seen were similar to those commonly found in rats of this age and strain. None were considered treatment-related.
There were no observations in the haematology determinations considered to be treatment related. In the clinical chemistry determinations, there was a statistically significant increase in plasma alkaline phosphatase activity of males given 4000 ppm and statistically significant increases in plasma cholesterol levels of females given 900 and 4000ppm. There were other statistically significant differences between control and PROXEL Press Paste treated groups in the clinical chemistry determinations however these were small and/or not dose-related and therefore were not considered to be treatment-related.
Some statistically significant differences were seen in organ weights but these were marginal and/or not dose-related and are considered to be incidental to treatment with PROXEL Press Paste. The only macroscopic finding attributed to treatment with PROXEL Press Paste was a thickened limiting ridge in the stomach which was present in ten males and ten females given 4000 ppm and one male and one female given 900ppm. Histopathological examination of all tissues (apart from the stomach, lung, kidney and liver which were examined from all animals) was confined to the control and the 4000 ppm groups. In eleven males and eleven females given 4000ppm there was minimal, slight or moderate hyperplasia of the forestomach adjacent to the limiting ridge. A mixed inflammatory cell submucosal infiltrate accompanied the hyperplastic change in two males and six females. One of the females had minimal ulceration with submucosal haemorrhage in the forestomach and there was slight focal hyperplasia in the oeosophagus of one male given 4000 ppm. Extra sections of stomach from the block and wet tissue were examined from the male and female given 900 ppm reported as having thickened limiting ridges in the stomach at macroscopic examination. These were normal on microscopic examination. There were no other microscopic findings considered to be related to treatment with PROXEL Press Paste.

Conclusion
The administration of 4000 ppm PROXEL Press Paste for 90 consecutive days resulted in a reduced growth rate without signs of overt toxicity. Histopathological changes in the stomach at 4000ppm were ascribed to an irritant effect of the test substance.
The toxicological no effect level, on the basis of this 90 day feeding study, is 900ppm PROXEL Press Paste.
The study was conducted in compliance with US EPA PAG 82-1, but can also be considered to be compatible with EC B.26 (a minor exception is that the weights of the epididymides, uterus, ovaries, thymus and heart were not recorded, however, macro- and micro-scopic examinations of these tissues allows their exclusion as target organs for PROXEL Press Paste toxicity).

LO(A)EL 4000 ppm equivalent to 322.0 mg/kg/day in males and 356.3 mg/kg/day in females (based on reduced growth rate and histopathological changes in the stomach)
NO(A)EL 900 ppm equivalent to 69.0 mg/kg/day in males and 78.3 mg/kg/day in females

Executive summary:

A study was conducted to determine the sub-chronic repeat dose toxicity of the substance according to US EPA Guideline OPP 82 -1. Groups of twelve male and twelve female Alpk:APfSD rats were fed diets containing 0, 200, 900 or 4000 ppm of the test substance for a period of 90 days. The food consumption and bodyweight were monitored throughout the study and the average dose received by the animals in the 200, 900 and 4000 ppm groups was calculated as 15.3, 69.0 and 322.0 mg/kg/day for males, and 17.6, 78.3 and 356.3 mg/kg/day for females, respectively. During the study the rats were observed daily for changes in clinical conditions and behaviour and once weekly a detailed examination of each rat was performed. An ophthalmoscopic examination of all animals in the control and 4000 ppm was performed prior to the start of the study and then during the week prior to termination. After 90 days of treatment all surviving animals were sacrificed and blood samples taken for haematological and clinical biochemistry examination.  A full macroscopic examination was performed on all animals and the adrenal glands, kidneys, liver, brain and testes were weighed.  Microscopic examination was performed on liver, kidney, lung and stomach samples from all animals and on all processed tissues from the control and 4000 ppm dose group. There were no mortalities, all animals were observed to be in good clinical condition and any clinical signs recorded were considered to be of a type and incidence commonly seen in rats of this age and strain and therefore not considered to be treatment-related. The bodyweights of animals at the high dose were statistically significantly reduced throughout the study and a corresponding decrease in food consumption in the females of the high dose group. There was no effect on bodyweight at any other dose level. There were no observations in the haematology determinations considered to be treatment-related. A statistically significant increase in plasma alkaline phosphatase activity of males at high dose and statistically significant increases in plasma cholesterol levels of females at mid and high doses were observed. No macroscopic abnormalities were observed during necropsy of the test animals. The only macroscopic finding attributed to treatment was a thickened limiting ridge in the stomach of majority of the animals at high dose, which corresponded to the presence of a minimal, slight or moderate hyperplasia of the forestomach adjacent to the limiting ridge. A mixed inflammatory cell submucosal infiltrate accompanied the hyperplastic change in two males and six females. Based on the reduction in body weight and food consumption at the high dose, the sub-chronic systemic NOAEL of the substance in rats was determined to be 900 ppm (69.0 mg/kg/day in males and 78.3 mg/kg/day in females) (Whiles, 1991).