Registration Dossier

Administrative data

Endpoint:
acute toxicity: oral
Type of information:
experimental study
Adequacy of study:
key study
Study period:
The study was undertaken between 16 January and 13 February 1986.
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: Study conducted in accordance with generally accepted scientific principles, possibly with incomplete or methodological deficiencies, which do not affect the quality of relevant results.

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
1986
Report Date:
1986

Materials and methods

Test guidelineopen allclose all
Qualifier:
equivalent or similar to
Guideline:
EU Method B.1 (Acute Toxicity (Oral))
Deviations:
no
Qualifier:
according to
Guideline:
EPA OTS 798.1175 (Acute Oral Toxicity)
Deviations:
no
GLP compliance:
not specified
Test type:
standard acute method
Limit test:
no

Test material

Reference
Name:
Unnamed
Type:
Constituent
Details on test material:
Test material as named in report: DIXT". Di-isopropyl xanthogen tetrasulphide (polysulphide).
Appearance: Clear yellow liquid.
- Storage condition of test material: ambient temperature in the dark

Test animals

Species:
rat
Strain:
Sprague-Dawley
Sex:
male/female
Details on test animals and environmental conditions:
TEST ANIMALS
- Source: Obtained from Charles River U.K. Limited, Margate, Kent, England.
- Age at study initiation: Four to six weeks of age.
- Weight at study initiation: 98 to 149 g.
- Fasting period before study: Access to food was prevented overnight prior to and approximately 4 hours after dosing.
- Housing: Rats were housed in groups by sex in metal cages with mire mesh floors.
- Diet (e.g. ad libitum): A standard laboratory rodent diet (Labsure LAD 1) was provided ad libitum.
- Water (e.g. ad libitum): Water was provided ad libitum.
- Acclimation period: Minimum period of 6 days prior to the start of the main study.

ENVIRONMENTAL CONDITIONS
- Temperature (°C): The mean daily minimum and maximum temperatures were 20°C and 22°C.
- Humidity (%): The mean daily relative humidity value was 60%.
- Air changes (per hr): The rate of air exchange was maintained at approximately 15 air changes/hour.
- Photoperiod (hrs dark / hrs light): Lighting was controlled by means of a time switch to give 12 hours artificial light in each 24 hour period.

Administration / exposure

Route of administration:
oral: gavage
Vehicle:
unchanged (no vehicle)
Details on oral exposure:
MAXIMUM DOSE VOLUME APPLIED: 4.92 ml/kg


Doses:
Main study: 1.0, 1.6, 2.5, 4.0 and 6.4 g/kg
No. of animals per sex per dose:
5 males and 5 females per dose.
Control animals:
no
Details on study design:
- Duration of observation period following administration: 14 days after dosing.

- Frequency of observations and weighing: Animals were observed soon after dosing, then at frequent intervals for the remainder of Day 1. On subsequent days the animals were observed once in the morning and once at the end of the experimental day. Clinical signs were recorded at each observation.
Individual bodyweights of rats on Days 1 (day of dosing), 8, 15 and at death were recorded.

- Necropsy of survivors performed: Surviving animals on the main study were killed on Day 15 by cervical dislocation. All animals that died during the study and those killed on Day 15 were subjected to a macroscopic post mortem examination which consisted of opening the abdominal and thoracic cavities. The macroscopic appearance of abnormal organs when present was recorded.

- Other examinations performed: The following were recorded during the main study:-
- Approximate time of death of individual rats
- The nature, severity, approximate time of onset and duration of each toxic sign.

Statistics:
The acute median lethal oral dose (LD50) to male and female rats was calculated using the method of:
Finney (1971) Probit Analysis (3rd Edition) Cambridge University Press.

Separate LD so values for males and females were estimated by undertaking probit analysis on the mortality data by fitting two parallel lines on the data (males only and females only) using the technique described by Finney (1978, Statistical Method in Biological Assay, 3rd Edition, Charles Griffin, London). A chi-squared test was carried out to check that the data did not contain any evidence for non-parallelism.

Results and discussion

Preliminary study:
The results of the preliminary study indicated that the LD50 was between 2.5 - 5.0 g/kg bodweight (see Table 1 - attached background material).
Effect levels
Sex:
male/female
Dose descriptor:
LD50
Effect level:
1 500 mg/kg bw
Based on:
test mat.
95% CL:
400 - 2 400
Mortality:
Mortalities occurred amongst rats dosed at 1.0 g/kg and above within two and 71 hours of dosing (see table 2 - attached background material).

Sex: Male; Dose: 1.0 g/kg; Number of deaths in group of 5; 1
Sex: Male; Dose: 1.6 g/kg; Number of deaths in group of 5; 4
Sex: Male; Dose: 2.5 g/kg; Number of deaths in group of 5; 2
Sex: Male; Dose: 4.0 g/kg; Number of deaths in group of 5; 5
Sex: Male; Dose: 6.4 g/kg; Number of deaths in group of 5; 5
Sex: Female; Dose: 1.0 g/kg; Number of deaths in group of 5; 4
Sex: Female; Dose: 1.6 g/kg; Number of deaths in group of 5; 0
Sex: Female; Dose: 2.5 g/kg; Number of deaths in group of 5; 3
Sex: Female; Dose: 4.0 g/kg; Number of deaths in group of 5; 4
Sex: Female; Dose: 6.4 g/kg; Number of deaths in group of 5; 4
Clinical signs:
Signs of reaction to treatment observed shortly after dosing amongst rats of all groups were pilo-erection, abnormal body carriage (hunched posture), abnormal gait (waddling), lethargy, decreased respiratory rate, pallor of the extremities and diuresis. These were accompanied by:
ptosis in all rats dosed at 1.6 g/kg and above,
increased salivation in all rats dosed at 1.6 g/kg,
abdominal distension in one male rat dosed at 2.5 g/kg,
a coma-like condition in one male rat dosed at 2.5 g/kg.

Recovery, as judged by external appearance and behaviour, was apparently complete by Days 7 to 11.

See table 4 (attached background material) for results.
Body weight:
Bodyweight losses were recorded for all but one of the rats that died (Table 5 - attached background material).
Bodyweighy gains were recorded for all surviving rats on Days 8 and 15 (Table 5 - attached background material).
Gross pathology:
Animals that died during study:
Autopsy revealed pallor of the liver, spleen and kidneys and congestion of the blood vessels of the small and large intestine amongst rats that died. Perforations of the duodenum were seen amongst rats at all dose levels. A light yellow fluid was found in the peritoneal cavity of three rats dosed at 4.0 g/kg and one female dosed at 6.4 g/kg ( seeTable 3 – attached background material).

Terminal autopsy:
Terminal autopsy revealed perforations in the duodenum in a small number of animals. Enlargement of the spleen was seen in one female rat dosed at 2.5 g/kg (see Table 6 - attached background material).

Any other information on results incl. tables

Estimation of the LD50 value

The acute median lethal oral dose of D.I.X.T. and its 957% confidence limits were estimated to be:

Males and females combined: 1.5 (0.40 to 2.4) g/kg bodyweight.

The slope of the probit line was 1.9 with a standard error of 0.71 using log. transformation of dose. The heterogeneity factor was not significant.

 

When probit analysis was carried out by fitting two parallel lines the values were:

Males only: 1.3 (0.22 to 2.5) g/kg bodyweight.

Females only: 1.8 (0.50 to 3.5) g/kg bodyweight.

The slope of the parallel probit lines was 1.9 with a standard error of 0.71 using log. transformation of dose. The heterogeneity factor was significant.

 

The mortality response curves are presented in Figure 1 (see attached background material).

 

The chi-squared test for parallelism gave no evidence of non-parallelism.

Applicant's summary and conclusion

Interpretation of results:
harmful
Remarks:
Migrated information Criteria used for interpretation of results: EU
Conclusions:
The acute median lethal dose (LD50) and their 95% confidence limits to rats of D.I.X.T. were estimated to be:
Males and females combined: 1.5 (0.40 to 2.4) g/kg bodyweight.
Males only: 1.3 (0.22 to 2.5) g/kg bodyweight.
Females only: 1.8 (0.50 to 3.5) g/kg bodyweight.
Executive summary:

Introduction:

The experimental procedure used followed the Testing Guidelines as described in the Federal Register, Vol 50, No.188, Part II of 27 September 1985, Section 798.1175 - Acute Oral Toxicity.

Method:

A preliminary test was carried out to establish a dosing regimen using groups of two males and two female rats at three dose levels of 1.0, 2.5 and 5.0 g/kg bodyweight.

Based on the findings of the preliminary test, further groups of rats (5 male and 5 female per dose group) were dosed at dose levels of 1.0, 1.6, 2.5, 4.0 and 6.4 g/kg bodyweight. The appropriate dose volume of the test substance was administered to each rat using a syringe and plastic catheter or a glass microlitre syringe and metal cannula.

Animals were observed soon after dosing, then at frequent intervals for the remainder of Day 1. On subsequent days the animals were observed once in the morning and once at the end of the experimental day. Clinical signs were recorded at each observation.

Individual bodyweights of rats on Days 1 (day of dosing), 8, 15 and at death were recorded.

Surviving animals on the main study were killed on Day 15 by cervical dislocation. All animals that died during the study and those killed on Day 15 were subjected to a macroscopic post mortem examination which consisted of opening the abdominal and thoracic cavities. The macroscopic appearance of abnormal organs when present was recorded.

Results:

The results of the preliminary study indicated that the acute median lethal oral dose of D.I.X.T was between 2.5 and 5.0 g/kg bodyweight.

Main test:

Mortalities:

Mortalities occured amonhst rats dosed at 1.0 g/kg and above within two and 71 hours of dosing. Autopsy revealed pallor of the liver, spleen and kidneys and congestion of the blood vessels of the small and large intestine amongst rats that died. Perforations of the duodenum were seen amongst rats at all dose levels. A light yellow fluid was found in the peritoneal cavity of three rats dosed at 4.0 g/kg and one female dosed at 6.4 g/kg. Bodyweighy losses were recorded for all but one of the rats that died.

Clinical signs:

Signs of reaction to treatment observed shortly after dosing amongst rats of all groups were pilo-erection, abnormal body carriage (hunched posture), abnormal gait (waddling), lethargy, decreased respiratory rate, pallor of the extremities and diuresis. These were accompanied by:

- ptosis in all rats dosed at 1.6 g/kg and above,

- increased salivation in all rats dosed at 1.6 g/kg,

- abdominal distension in one male rat dosed at 2.5 g/kg,

- a coma-like condition in one male rat dosed at 2.5 g/kg.

Recovery, as judged by external appearance and behaviour, was apparently complete by Days 7 to 11.

Bodyweight:

Bodyweight gains were recorded for all surviving rats on Days 8 and 15.

Terminal autopsy:

Terminal autopsy revealed perforations in the duodenum in a small number of animals. Enlargement of the spleen was seen in one female rat dosed at 2.5 g/kg.

Conclusion:

The acute median lethal dose (LD50) and their 95% confidence limits to rats of D.I.X.T. were estimated to be:

Males and females combined: 1.5 (0.40 to 2.4) g/kg bodyweight.

Males only: 1.3 (0.22 to 2.5) g/kg bodyweight.

Females only: 1.8 (0.50 to 3.5) g/kg bodyweight.