4-[(morpholinothio)thioxomethyl]morpholine

Repeated dose toxicity: oral

Administrative data

Endpoint:

chronic toxicity: oral

Remarks:

combined repeated dose and carcinogenicity

Type of information:

experimental study

Adequacy of study:

key study

Reliability:

2 (reliable with restrictions)

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

1984

Report date:

1984

Materials and methods

Test guideline

Qualifier:

according to guideline

Guideline:

EPA OPP 82-5

GLP compliance:

yes

Test material

Test material information

Constituent 1

Reference substance name:

4-[(morpholinothio)thioxomethyl]morpholine

EC Number:

237-335-9

EC Name:

4-[(morpholinothio)thioxomethyl]morpholine

Cas Number:

13752-51-7

Molecular formula:

C9H16N2O2S2

IUPAC Name:

morpholin-4-yl morpholine-4-carbodithioate

Constituent 2

Reference substance name:

Commercial Cure-Rite® 18; purity: 96.8%

IUPAC Name:

Commercial Cure-Rite® 18; purity: 96.8%

Test animals

Species:

rat

Strain:

Sprague-Dawley

Sex:

male/female

Administration / exposure

Route of administration:

oral: feed

Vehicle:

other: certified laboratory diet (Purina Lab Chow (R)

Details on oral exposure:

Route: Oral via dietary admixture.
Frequency: Continously
Duration 26 months
Dates of treatment: 1 July 1980 to 23 August 1983

Analytical verification of doses or concentrations:

yes

Details on analytical verification of doses or concentrations:

2 x 4 oz samples were taken from each dose level monthly. One sample was analyzed and the other was stored frozen or submitted to sponsor (Week 4, 13, 30, 43, 56, 69, 82, 95, 108).

Duration of treatment / exposure:

2 years

Frequency of treatment:

Fresh feed was presented every 3 or 4 days.

Doses / concentrations

Remarks:

Doses / Concentrations:
0, 20, 60, 200, and 600 ppm
Basis:
nominal in diet

No. of animals per sex per dose:

60/sex/dose

Control animals:

yes, concurrent no treatment

Details on study design:

Diets containing 0, 20, 60, or 600 ppm of the test material were
administered to groups (60/sex/group) of Sprague-Dawley rats for 112
weeks. Ten rats/sex/group were identified for a 12 month interim sacrifice.
Animals were checked twice daily for mortality and gross signs of toxicity. A
detailed physical exam palpation for tissue masses was performed weekly.
Body weight and feed consumption were measured weekly through week
12 and biweekly from week 13 to 26 and monthly thereafter. Hematology,
clinical chemistry, and urinalysis were conducted pretest on 15 animals/sex
and at months 6, 12, 18, and 24. Animals were given a complete gross
post mortem examination following spontaneous death, death in extremis,
or scheduled sacrifices. A full set of organs were subjected to gross and
histological examination. All tissues from the control and high dose were
processed for pathological examination at 12 months and termination.
Tissues in mid and low dose groups were identified for pathological
evaluation based on the pathological evaluations in the controls and high
dose groups. Organs also were weighed. Furthermore, the testes from 3
of the 10 males at 12 months were processed for electron and light
microscopy examination. Statistical analyses were conducted on the end
points.

Examinations

Observations and examinations performed and frequency:

Animals were checked twice daily for mortality and gross signs of toxicity. A
detailed physical exam palpation for tissue masses was performed weekly.
Body weight and feed consumption were measured weekly through week
12 and biweekly from week 13 to 26 and monthly thereafter. Hematology,
clinical chemistry, and urinalysis were conducted pretest on 15 animals/sex
and at months 6, 12, 18, and 24. Animals were given a complete gross
post mortem examination following spontaneous death, death in extremis,
or scheduled sacrifices. A full set of organs were subjected to gross and
histological examination. . Furthermore, the testes from 3
of the 10 males at 12 months were processed for electron and light
microscopy examination. Statistical analyses were conducted on the end
points.

Sacrifice and pathology:

All tissues from the control and high dose were
processed for pathological examination at 12 months and termination.
Tissues in mid and low dose groups were identified for pathological
evaluation based on the pathological evaluations in the controls and high
dose groups. Organs also were weighed.

Other examinations:

Body weights also were significantly lower in the high dose males and females.

Statistics:

mean values of all dose groups were compared to control at each time interval.

Results and discussion

Results of examinations

Clinical signs:

effects observed, treatment-related

Description (incidence and severity):

Males - possible slight effect of test material on long term survival. Females - mortality in control and treated was considered comparable.

Mortality:

mortality observed, treatment-related

Description (incidence):

Males - possible slight effect of test material on long term survival. Females - mortality in control and treated was considered comparable.

Body weight and weight changes:

effects observed, treatment-related

Description (incidence and severity):

M+F lower weights than controls for 600ppm group. Body weights of other groups (20, 60, and 200ppm) were comparable or greater than control weights.

Food consumption and compound intake (if feeding study):

effects observed, treatment-related

Description (incidence and severity):

Consumption values do not appear to show a significant toxic affect of administration.

Haematological findings:

effects observed, treatment-related

Description (incidence and severity):

Female 600ppm dose showed some decrease but were within normal physiological parameters. Other female groups and male groups showed no differences to controls.

Urinalysis findings:

no effects observed

Description (incidence and severity):

analyses of urine for gross appearance, specific gravity, pH, protein, glucose, ketones, bilirubin and occult blood failed to reveal any differences in the treated animals compared to controls.

Organ weight findings including organ / body weight ratios:

effects observed, treatment-related

Description (incidence and severity):

kidneys, liver and/or spleens were elevated at 12 and 26 months compared to controls. Pituitary, brain, adrenals, heart, testes and ovaries revealed no difference between control and treated groups.

Gross pathological findings:

effects observed, treatment-related

Histopathological findings: non-neoplastic:

no effects observed

Histopathological findings: neoplastic:

effects observed, treatment-related

Description (incidence and severity):

kidneys, lungs, testes, adrenals, and mammary glands.

Effect levels

Dose descriptor:

NOAEL

Based on:

test mat.

Sex:

male/female

Basis for effect level:

other: overall effects clinical signs; body weight; food consumption; ophthalmoscopic examination; haematology; clinical chemistry; urinalysis; gross pathology; organ weights; histopathology;

Remarks on result:

not determinable

Remarks:

no NOAEL identified

Target system / organ toxicity

Critical effects observed:

not specified

Applicant's summary and conclusion

Executive summary:

This study was designed to assess the toxicity and carcinogenicity of Cure-Rite 18 when administered via dietary admixture 7 days per week for 24 to 30 months at dose levels of: 20, 60, 200, and 600 ppm. A control group was administered untreated feed. A total of 600 animals were randomly divided into five groups of 60 rats/sex/ group. After 12 months, 10 rats/sex/group were selected for an interim sacrifice. All surviving animals were sacrificed after 26 months of treatment. Body weights, food consumption and environmental conditions were monitored periodically. Selected hematology, clinical chemistry and urinalysis parameters were evaluated pretest and after 6, 12, 18 and 24 months. Complete gross necropsy examinations were performed on all animals; organs were weighed and organ/body weight ratios were calcuated at Months 12 and 26. Microscopic examinations were performed on selected tissues. Excluding animals killed accidentally or for reasons unrelated to test material administration, mortality occurred in 36 of 60 males in the 200 ppm

group and 34 of 60 males in the 600 ppm group as compared to 27 of 60 males in the control group. Although these differences are not statistically significant, they do suggest a possible slight effect of Cure-Rite 18 on long-term survival in males. Mortality in females was comparable among groups. Temperature and humidity in the room housing these animals varied over the course of the study; the majority of values were within ranges specified in the protocol. Average monthly values were 68-73'F and 34-63% relative humidity. (The protocol specified 67-76'F and 40-60% relative humidity). Room air changes ranged from 10.3 to 12.4 fresh air changes per hour.

 A clear treatment-related increase in the presence of rales was seen in animals receiving the highest dose level (600 ppm) of Cure-Rite 18, with almost 100% of the high-dose animals being affected. This first became evident after approximately three months of treatment and persisted throughout the remainder of the study. The incidence of rales in animals at lower doses was considered comparable to that seen in control animals. No other physical abnormalities attributed to test material administration were seen. Body weights of high-dose males and females were statistically significantly lower than weights of control animals throughout the study. Mean weights were within 10% of control values through Month 15 for the males and through Month 12 for the females but exceeded 10% thereafter. No consistent differences in food consumption values considered to be related to Cure-Rite 18 administration were apparent. Mean hemoglobin, hematocrit and total erythrocyte values for females in the high dose group were slightly lower than concurrent control means at Months 6, 12 and 18 {but not at Month 24}. The consistency of these slight decreases over the first 18 months of the study suggests a possible minimal effect of the test material on these parameters. However, most values for this group were within normal physiologic ranges. Evaluation of platelet counts, prothrombin times and total and differential leukocyte counts revealed no consistent dose-related differences considered attributable to administration of Cure-Rite 18. Except for isolated instances of increased blood urea nitrogen values in individual high-dose animals, clinical chemistry evaluations revealed no differences between control and treated groups considered attributable to Cure-Rite 18 administration. Urinalysis values of control and treated animals were considered to be comparable. Kidney weights and kidney/body weight ratios for high-dose males and females were higher than control values at both the 12 month and 26 month {terminal} necropsy intervals. Other organ weight changes occurred sporadically with no apparent relationship to test material administration.Gross and microscopic postmortem examinations revealed lesions in the organs of the urinary system (kidneys, ureters and urinary bladders) of high-dose animals which were attributed to administration of Cure-Rite 18. The

most significant finding was the presence of neoplasms {benign and malignant} of the urothelium of the kidneys, ureters and/or urinary bladders of 16 of the 60 males and 15 of the 60 females in this group. The only other urothelial neoplasm seen in this study was a benign urothelial papilloma of the renal pelvis of one of 60 male rats in the control group. Other microscopically observed abnormalities which occurred at a higher incidence in the high-dose group than in other groups included cortical or medullary mineralization,

hydronephrosis, papillary necrosis and hemorrhage, blood in the kidneys, urothelial hyperplasia and blood in the urinary bladder. Grossly observed abnormalities of the urinary system seen at a high incidence in this group included enlargements, thickening or distention, surface irregularities, the presence of blood in the lumen, grossly evident masses or nodules and dilation of the renal pelvis.

 

Other neoplastic and non-neoplastic abnormalities occurred with comparable incidences in control and treated groups or were considered to be spontaneous occurrences unrelated to Cure-Rite 18 administration. There were no neoplastic or non-neoplastic changes in lower dose group (20, 60 or 200 ppm) ch were considered attributable to Cure-Rite 18 administration.