Registration Dossier

Administrative data

Endpoint:
sub-chronic toxicity: oral
Type of information:
migrated information: read-across from supporting substance (structural analogue or surrogate)
Adequacy of study:
key study
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
other: GLP-compliant guideline study, available as unpublished report, no restrictions, fully adequate for assessment.

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
2003
Report Date:
2003

Materials and methods

Test guidelineopen allclose all
Qualifier:
according to
Guideline:
OECD Guideline 408 (Repeated Dose 90-Day Oral Toxicity in Rodents)
Qualifier:
according to
Guideline:
EU Method B.26 (Sub-Chronic Oral Toxicity Test: Repeated Dose 90-Day Oral Toxicity Study in Rodents)
Qualifier:
according to
Guideline:
EPA OPPTS 870.3100 (90-Day Oral Toxicity in Rodents)
GLP compliance:
yes (incl. certificate)
Limit test:
no

Test material

Reference
Name:
Unnamed
Type:
Constituent
Type:
Constituent
Details on test material:
- Name of test material (as cited in study report): SDDC (sodium dimethyldithiocarbamate)
- Molecular formula (if other than submission substance): C3H7NS2Na
- Molecular weight (if other than submission substance): 143.209 g/mol
- Smiles notation (if other than submission substance): C(N(C)C)(=S)[S-].[Na+]
- InChl (if other than submission substance): InChI=1/C3H7NS2.Na/c1-4(2)3(5)6;/h1-2H3,(H,5,6);/q;+1/p-1
- Substance type: inorganic
- Physical state: yellow coloured liquid
- Analytical purity: 41.44% (aqueous solution)
- Purity test date: 18-12-2001
- Expiration date of the lot/batch: 20-05-2003
- Storage condition of test material: approximately 4 ˚C, under nitrogen

Test animals

Species:
rat
Strain:
Sprague-Dawley
Sex:
male/female
Details on test animals and environmental conditions:
TEST ANIMALS
- Source: Charles River (UK) Limited, Margate, Kent, UK
- Age at study initiation: 5-8 weeks
- Weight at study initiation: males: 164-217 g, females: 143-193 g
- Housing: in groups of 5 by sex in polypropylene grid-floor cages suspended over trays lined with absorbent paper.
- Diet: a pelleted diet (Rat and Mouse SQC Diet No. 1, Special Diets Services Limited, Witham, Essex, UK), ad libitum
- Water: Mains drinking water from polycarbonate bottles attached to the cage, ad libitum
- Acclimation period: 7 days

ENVIRONMENTAL CONDITIONS
- Temperature (°C): 21 ± 2
- Humidity (%): 55 ± 15
- Air changes (per hr): at least 15 per hour
- Photoperiod (hrs dark / hrs light): 12/ 12

IN-LIFE DATES: From: To:

Administration / exposure

Route of administration:
oral: gavage
Vehicle:
water
Details on oral exposure:
PREPARATION OF DOSING SOLUTIONS: the test material was prepared at the appropriate concentrations as solution in distilled water. Formulations were stable for at least 3 days. Fresh formulations were therefore prepared daily and used wherever possible within 3 hours of preparation. Correction for 41% purity was taken into account.

Analytical verification of doses or concentrations:
yes
Details on analytical verification of doses or concentrations:
Samples were taken once weekly of each test material formulation and analysed for concentration of SDDC at Safepharm Analytical Laboratory by gas chromatography. The results indicate that the prepared formulations were on most occasions within ±10% of nominal.
Duration of treatment / exposure:
90 consecutive days
Frequency of treatment:
Daily
Doses / concentrations
Remarks:
Doses / Concentrations:
0. 10, 50 and 250 mg/kg bw/day
Basis:
nominal in water
No. of animals per sex per dose:
10/sex/dose
Control animals:
yes, concurrent vehicle
Details on study design:
- Dose selection rationale: based on the results of a range-finding study
- Rationale for animal assignment (if not random): the animals were randomly allocated to treatment grouops using random letter tables and the group mean bodyweights were then determined to ensure similarity between the treatment groups

Examinations

Observations and examinations performed and frequency:
CAGE SIDE OBSERVATIONS: Yes
- Time schedule: all animals were examined for overt signs of toxicity, ill-health or behavioural change immediately before dosing and one and 5 hours after doing during the working week. Animals were observed immediately before dosing and one hour after dosing at weekends and public holidays.

DETAILED CLINICAL OBSERVATIONS: Yes
Detailed individual clinical observations were performed on each animal using a purpose built arena. The following parameters were observed: gait, tremors, twitches, convulsions, bizarre/abnormal/stereotypic behaviour, salivation, piloerection, exophthalmia, lachrymation, hyper/hypothermia, skin colour, respiration, palpebral closure, urination, defecation, trasfer arousal, tail elevation.

BODY WEIGHT: Yes
- Time schedule for examinations: at day 0 (the day before the start of treatment) and at weekly intervals thereafter. Bodyweights were also recorded at terminal kill.

FOOD CONSUMPTION: yes
Food consumption was recorded for each group at weekly intervals throughout the study.

WATER CONSUMPTION AND COMPOUND INTAKE (if drinking water study): Yes
- Time schedule for examinations: daily, by visual inspection of the water bottles for any overt change.

OPHTHALMOSCOPIC EXAMINATION: Yes
- Time schedule for examinations: pre-treatment and before termination of treatment (during week 12)
- Dose groups that were examined: control and high-dose animals

HAEMATOLOGY: Yes
- Time schedule for collection of blood: at the end of the study (day 90); where necessary, repeat were obtained on day 21.
- Anaesthetic used for blood collection: No data
- Animals fasted: No
- How many animals: all animals from each test and control groups
- Parameters examined: haemoglobin (Hb), erythrocyte count (RBC), haematocrit (Hct), erythrocyte indices (mean corpuscular haemoglobin, mean corpuscular volume, mean corpuscular haemoglobin concentration), total leucocyte count (WBC), differential leucocyte count (neutrophils, lymphocytes, monocytes, eosinophils, basophils), platelet count (PLT), reticulogyte count (Retic, prothrombin time and activated partial thromboplastin time.

CLINICAL CHEMISTRY: Yes
- Time schedule for collection of blood: at the end of the study (day 90); where necessary, repeat were obtained on day 21.
- Anaesthetic used for blood collection: No data
- Animals fasted: No
- How many animals: all animals from each test and control groups
- Parameters examined: urea, glucose, total protein, albumin, albumin/globulin ratio, sodium, potassium, chloride, calcium, inorganic phosphorus, aspartate aminotransferase, alanine aminotransferase, alkalline phosphatase, creatinine, total cholesterol, total bilirubin, cholinesterase

NEUROBEHAVIOURAL EXAMINATION: Yes
- Time schedule for examinations: prior to the start of treatent and at weekly intervals thereafter, all animals were observed for signs of functional/behavioural toxicity. During Week 12 functional performance tests were also performed on all animals together with an assessment of sensory reactivity to different stimuli.
- Dose groups that were examined: all
- Battery of functions tested: sensory reactivity, forelimb/hindlimb grip strength, motor activity

Sacrifice and pathology:
GROSS PATHOLOGY: Yes
HISTOPATHOLOGY: Yes. Samples of the following tissues were removed from all animals and preserved in buffered 10% formalin: adrenals, aorta (thoracic), bone & bone marrow (femur including stifle joint, sternum), brain (including cerebrum, cerebellum and pons), caecum, colon, duodenum, epididymides, eyes, gross lesions, heart, ileum (including Peyer's patches), jejunum, kidneys, liver, lungs (with bronchi), lymph nodes (cervical and mesenteric), mammary glands, muscle (skeletal), oesophagus, ovaries, pancreas, pituitary, prostate, rectum, salivary glands (submaxillary), sciatic nerve, seminal vesicles, skin (hind limb), spinal cord (cervical, mid-thoracic and lumbar), spleen, stomach, testes, thymus, thyroid/parathyroid, tongue, trachea, urinary bladder, uterus
Statistics:
Haematological, blood chemical, organ weight, weekly bodyweight gain and quantitative functional performance and sensory reactivity data were assessed for control and test material treatment groups for dose response relationships by linear regression analysuis followed by one way analysis of variance (ANOVA) incorporating Levene's test for homogeneity of variance. Wheere variances were shown to be homogenous pairwise comparisons were conducted using Dunnett's test. Where Levene's test showed unequal variances the data were analysed using non-parametric methods: Kruskal-Wallis ANOVA and Mann-Whitney "U" test.

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 examined
Water consumption and compound intake (if drinking water study):
no effects observed
Ophthalmological findings:
no effects observed
Haematological findings:
effects observed, treatment-related
Clinical biochemistry findings:
effects observed, treatment-related
Urinalysis findings:
not examined
Behaviour (functional findings):
effects observed, treatment-related
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:
CLINICAL SIGNS AND MORTALITY
There were no deaths. Increased salivation around the time of dosing was detected for animals of either sex treated with 250 mg/kg bw/day from day 1 or day 2 onwards, accompanied in females with associated isolated findings of red/brown staining and/or wetness of the external body fur and generalised fur loss. Females treated with 250 mg/kg bw/day also showed hunched posture and isolated signs of tiptoe gait from day 28. Instances of transient increased salivation were also seen in either sex treated with 50 mg/kg bw/day. Excessive visible salivation and its associated findings are commonly reported following the oral administration of a test material, and are considered to be attributable to the repeated administration of a locally irritant test material formulation by gavage rather than an indication of systemic toxicity. No treatment-related clinical signs were observed at 10 mg/kg bw/day.

BODY WEIGHT AND WEIGHT GAIN
Animals of either sex treated with 250 mg/kg bw/day showed reductions in bodyweight gain throughout the study period compared with controls. No adverse bodyweight effect was noted at the other dose levels.

FOOD CONSUMPTION:
A reduction in dietary intake was detected for animals of either sex treated with 250 mg/kg bw/day throughout the study period compared with controls. No noteworthy differences in food consumption were observed at the other dose levels.

WATER CONSUMPTION:
Daily visual inspection of water bottles revealed no overt intergroup differences.

OPHTHALMOSCOPIC EXAMINATION
There were no treatment-related ocular effects.

HAEMATOLOGY
A clear haemolytic effect was identified for animals treated with 250 mg/kg bw/day and likely also in animals treated with 50 mg/kg bw/day, characterised by a statistically significant reduction in erythrocyte count in animals treated with 250 mg/kg bw/day together with increases in mean corpuscular haemoglobin (MCH) and mean corpuscular volume (MCV). Males treated with 250 mg/kg bw/day also shwoed an increase in mean corpuscular haemoglobin concentration. An increase in MCH and MCV was also apparent in either sex treated with 50 mg/kg bw/day.

CLINICAL CHEMISTRY
Findings were confined to increases in plasma levels of total protein, sodium and cholesterol in males treated with 250 mg/kg bw/day.

NEUROBEHAVIOUR
Males treated with 250 or 50 mg/kg bw/day showed a statistically significant increase in total activity compared with controls. No treatment-related changes were detected for females or for 10 mg/kg bw/day males.
Females treated with 250 mg/kg bw/day showed statisitically significant increases in startle reflex for percentile average response, root of the mean square and peak response, compared with controls. A slight but statistically significant increase in percentile average response was also noted in females treated with 50 or 10 mg/kg bw/day but this was considered not to be toxicologically significant.

ORGAN WEIGHTS
Increases in kidney, liver and spleen weight were evident in both sexes treated with 250 mg/kg bw/day compared with controls. The other organs were unaffected and there were no other changes in organ weight that could be considered toxicologically important.

GROSS PATHOLOGY
Treatment-related gastric changes were detected in the majority of male animals treated with 250 mg/kg bw/day together with enlarged and darkened spleens in two males treated with 250 mg/kg bw/day. No treatment-related macroscopic abnormalities were detected for animals treated with 50 or 10 mg/kg bw/day.

HISTOPATHOLOGY: NON-NEOPLASTIC
The following treatment-related changes were detected:
Spleen: higher severities of extramedullary haemopoiesis were observed in relation to treatment for rats of either sex dosed at 250 mg/kg bw/day. A similar effect was also seen for male rats dosed at 50 mg/kg bw/day and 10 mg/kg bw/day. In addition, higher severities of pigment accumulation were seen for rats of either sex dosed at 250 mg/kg bw/day or at 50 mg/kg bw/day. The pigment was determined to be haemosiderin by Perl's staining technique.
Kidneys: a higher incidence and greater severity of pigment accumulation was seen in the renal tubules of rats of either sex dosed at 250 mg/kg bw/day and for male rats dosed at 50 mg/kg bw/day. The pigment was determined to be haemosiderin by Perl's staining technique.
Urinary bladder: there were indications of an effect of treatment on the transitional epithelium of the bladder resulting in hyperplasia. This is reasonably convincing for male rats dosed at 250 mg/kg bw/day, but for females, this condition is also present among control animals.
Thyroids: higher severities of follicular cell hyperthrophy were observed for male rats dosed at 250 mg/kg bw/day. A higher incidence of associated colloird depletion was also seen.
Stomach: acanthosis and heperkeratosis of the epithelium of the forestomach was seen among rats of either sex dosed at 250 mg/kg bw/day. Similar effects were also seen for male rats receiving 50mg/kg bw/day of the test material.
Duodenum: mucosal hypertrophy was seen for four males and for 1 female rat dosed at 250 mg/kg bw/day. This condition was considered to be related to treatment for male rats, but probably not for females.
Salivary glands: treatment-related atrophy of the serous acini of the submaxillary salivary glands was seen for rats of either sex receiving 250 mg/kg bw/day of the test material.
Bone marrow: lower severities of adipose infiltration of the bone marrow indicative of marrow hyperplasia were seen in female rats dosed at 250 mg/kg bw/day and 50 mg/kg bw/day.
All remaining morphological changes were those commonly observed in laboratory maintained rats of the age and strain employed. Although group differences in the incidence or severity of lesions occasionally attained statistical significance, none was considered to be related to treatment.

HISTOPATHOLOGY: NEOPLASTIC (if applicable)

HISTORICAL CONTROL DATA (if applicable)

OTHER FINDINGS

Effect levels

Dose descriptor:
NOAEL
Effect level:
10 mg/kg bw/day (actual dose received)
Based on:
act. ingr.
Sex:
male/female
Basis for effect level:
other: see 'Remark'

Target system / organ toxicity

Critical effects observed:
not specified

Applicant's summary and conclusion