Sodium dimethyldithiocarbamate

Repeated dose toxicity: oral

Administrative data

Endpoint:

chronic toxicity: oral

Type of information:

migrated information: read-across from supporting substance (structural analogue or surrogate)

Adequacy of study:

key study

Study period:

1993

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: see 'Remark'

Remarks:

GLP guideline study; According to the ECHA guidance document “Practical guide 6, V2: How to report read-across and categories” (Dec 2012), the reliability was changed from RL1 to RL2 to reflect the fact that this study was conducted on a read-across substance.

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

1993

Report date:

1993

Materials and methods

Test guideline

Qualifier:

equivalent or similar to guideline

Guideline:

OECD Guideline 452 (Chronic Toxicity Studies)

Deviations:

yes

Remarks:

The highest dose level produced one fatality and had therefore to be adjusted.

GLP compliance:

yes

Limit test:

no

Test material

Test material information

Constituent 1

Reference substance name:

Ziram

EC Number:

205-288-3

EC Name:

Ziram

Cas Number:

137-30-4

Molecular formula:

C6H12N2S4Zn

IUPAC Name:

zinc bis(dimethyldithiocarbamate)

Constituent 2

Reference substance name:

zinc bis dimethyldithiocarbamate

IUPAC Name:

zinc bis dimethyldithiocarbamate

Test animals

Species:

dog

Strain:

Beagle

Sex:

male/female

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Source: Interfauna UK Limited, Huntingdon, UK.
- Age at study initiation: 3-5 months
- Weight at study initiation: (♂) 8.8 - 11.5 kg, (♀) 8.2 – 10.7 kg

Administration / exposure

Route of administration:

oral: feed

Vehicle:

other: diet

Analytical verification of doses or concentrations:

yes

Duration of treatment / exposure:

52 weeks

Frequency of treatment:

daily

Doses / concentrations

Remarks:

Doses / Concentrations:
0, 50*, 185, 500# ppm (* Concentration was increased to 57.5 ppm to compensate losses during storage; # reduced from 700 to 500 ppm in week 12 because of treatment-related mortality)
Basis:
nominal in diet

No. of animals per sex per dose:

4 per sex

Control animals:

yes, plain diet

Positive control:

none

Examinations

Observations and examinations performed and frequency:

CLINICAL SIGNS
- Daily

MORTALITY
- Daily

BODY WEIGHT
- Weekly

FOOD CONSUMPTION
- Daily

ACHIEVED INTAKE
- Calculated weekly

OPHTHALMOSCOPIC EXAMINATIONS
- Pre-exposure and in weeks 13, 26 and 52

NEUROLOGICAL EXAMINATIONS
GENERAL
- Pre-exposure and in weeks 34 and 50
- Parameters: behaviour and gait

CRANIAL NERVE FUNCTION
- Pre-exposure and in weeks 34 and 50
- Parameters: head tilt, facial muscle, muscles of mastication, blink reflex (l & r), pupillary light reflex (l & r),eye position, strabismus, abnormal nystagmus, corneal reflex (l & r), palpebral reflex (l & r), ear movement, position of philtrum, commissure of lips, jaw closure, open jaw resistance, tongue, gag reflex

SPINAL REFLEXES
- Pre-exposure and in weeks 34 and 50
- Parameters: muscle tone, patellar reflex (l & r), triceps reflex (l & r), flexor reflex (all 4 limbs individually), crossed extensor reflex, perineal reflex

POSTURAL AND ATTITUDINAL REACTIONS
- Pre-exposure and in weeks 34 and 50
- Parameters: wheelbarrowing, thoracic hopping, pelvic hopping, extensor postural thrust, tactile placing, visual placing, tonic neck reaction, righting reaction

HAEMATOLOGY (jugular or cephalic vein)
- Pre-exposure and in weeks 13, 26 and 52
- Parameters: erythrocyte count, haemoglobin, haematocrit, mean corpuscular volume (MCV), mean corpuscular haemoglobin concentration (MCHC), platelet count, reticulocyte count, total leukocyte count, differential leukocyte count, prothrombin time (PT), activated partial thromboplastin time (APTT), cell morphology
erythrocyte sedimentation rate (ESR) was performed only in two cases as part of diagnostic screen

CLINICAL CHEMISTRY
- Pre-exposure and in weeks 13, 26 and 52
- Parameters: total protein, albumin, sodium, potassium, glucose, urea (BUN), alanine aminotransferase (ALT, GPT), aspartate aminotransferase (GOT), alkaline phosphatase (AP), creatinine, calcium, phosphorus, chloride, total cholesterol, total bilirubin, gamma-glutamyltransferase (GT), creatine phosphokinase (CPK), ornithine carbamoyltransferase (OCT), -hydroxybutyrate dehydrogenase (-HBDH), tri-iodothyronine (T3), thyroxine (T4)

URINALYSIS
- Pre-exposure and in weeks 13, 26 and 52
- Parameters: protein, glucose, pH, specific gravity, volume, ketones, haem pigments, bile pigments, urobilinogen, total reducing substances (TRS), epithelial cells (E), polymorphonuclear leukocytes (P), mononuclear leukocytes (M), erythrocytes (R), organisms (O), renal tubule casts (C), other abnormal constituents (A)

ORGAN WEIGHTS
- Yes
- Organs: adrenals, brain, heart, lung, kidneys, liver, ovaries/testes (with epididymides), spleen, pituitary, thymus, thyroids/parathyroids, uterus/prostate, pancreas

Sacrifice and pathology:

GROSS AND HISTOPATHOLOGY
- Gross pathology: all dose groups
- Adrenals, aorta, bones (sternum and femur), bone marrow (sternum), brain, caecum, colon, duodenum, eyes, gall bladder, heart, jejunum, ileum, kidneys, liver, lungs, lymph nodes, mammary gland, oesophagus, ovaries, pancreas, pituitary, prostate, rectum, salivary gland, sciatic nerves, skeletal muscle, skin, spleen, stomach, testes (with epididymides), thymus, thyroids/parathyroids, tongue, trachea, urinary bladder, uterus, vagina
Additionally: one bone marrow smear per dog.

Statistics:

All analyses were carried out both together and separately for male and female. In view of the small number of animals and to confirm possible effects, analyses were also performed on combined data.
Data relating to food consumption were analysed as totals over selected time periods, expressed on a weekly basis. Bodyweight data were analysed using weight gains.
The following tests were used for food consumption, bodyweight, organ weight and clinical pathology data:
- If the data consisted predominantly of one particular value (relative frequency of the mode exceeds 75%), the proportion of animals with values different from the mode was analysed by appropriate methods. Otherwise:
- Bartlett’s test was applied to test for heterogeneity of variance between treatments. Where significant (at the 1% level) heterogeneity was found, a logarithmic transformation was tried to see if a more stable variance structure could be obtained.
- If no significant heterogeneity was detected (or if a satisfactory transformation was found), a one-way analysis of variance was carried out. If significant heterogeneity of variance was present, and could not be removed by a transformation, the Kruskal-Wallis analysis of ranks was used.
- For pre-dose data, analyses of variance were followed by Student’s ‘t’ test. For data from the dosing period, analyses of variance were followed by Williams’ test for a dose-related response. The Kruskal-Wallis analyses were followed by the non-parametric equivalents of the ‘t’ test and Williams’ test (Shirleys’ test).
Where appropriate, analysis of covariance was used in place of analysis of variance. Statistical analysis in histopathological examination was performed using Fisher’s exact and Mantel’s tests.

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):

no effects observed

Food efficiency:

not examined

Water consumption and compound intake (if drinking water study):

not examined

Ophthalmological findings:

no effects observed

Haematological findings:

no effects observed

Clinical biochemistry findings:

effects observed, treatment-related

Urinalysis findings:

no effects observed

Behaviour (functional findings):

no effects observed

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:

not examined

Details on results:

CLINICAL SIGNS AND MORTALITY
- Occasional liquid faeces was noted in all dose-groups including controls during the entire study and was considered to be not related to treatment.
- One treatment-related death occurred at the initial high dosage level of 700 ppm during week 11. After a convulsion, the female showed a collapsed state with excessive salivation, trembling, champing of the jaws and jerking of the limps. Pathological findings demonstrated changes consistent with the collapsed state. As a result the high dosage level was reduced to 500 ppm.
One further mortality was treatment-unrelated (suspected polyarteritis) and a replacement dog was obtained.

BODY WEIGHT AND WEIGHT GAIN
- After 26 weeks all females at 185 und 500 ppm showed some weight loss, such that overall gain after 52 weeks was significantly reduced.

COMPOUND INTAKE
- Calculated on a weekly basis by (ppm x food consumption)/(mid-week bodyweight x 7).
The means over the treatment period are:
1.6, 6.6, 17.4 mg/kg bw/day for males
1.9, 6.7, 20.6 mg/kg bw/day for females

CLINICAL CHEMISTRY
- ALT values had intergroup differences amongst males (not statistically significant): 1 dog (185 ppm) and 2 dogs (500 ppm) showed elevated ALT in week 26 and 52. Since these animals showed the most marked changes in the liver microscopic examination, it was considered that these changes were treatment-related.
- AP values showed an apparent dosage-related increase amongst males receiving 185 or 500 ppm in week 26 and 52, although differences were not statistically significant but considered as a result of treatment and are probably associated with the pathological findings seen in the liver of these dogs at termination.
- The decrease in albumin was not supported by any significant corroborative pathological finding at termination and was considered of equivocal toxicological importance.

ORGAN WEIGHTS
- Liver weights for males receiving 500 ppm were increased but didn’t show any histopathological changes.
- Group mean heart weights were decreased for animals at 500 ppm.
- Group mean prostate weights showed a dosage-related decrease compared with the control data, although the differences did not attain statistical significance. There were no macro- or microscopic findings for these tissues.

GROSS PATHOLOGY
- Multiple red discoloured linear depressions of gastric mucosa for 1 female at 185 ppm and a single oval, flat friable choleliths in the gall bladders of 2 males at 185 ppm. No similar findings were seen in any dog at the 500 ppm treatment level.

HISTOPATHOLOGY: NON-NEOPLASTIC
- Liver and spleen are the target organs. Foci of degenerate hepatocytes were seen to a moderate degree at 500 ppm and at 185 ppm with a single cell necrosis in one male at 500 ppm. Inflammatory cell infiltration around central veins and sometimes around the branches of the hepatic vein was seen in some dogs. An apparent increase in centrilobular fibrocytes was seen in 3/4 male dogs treated with 500 ppm and in 1/4 male dog treated with 185 ppm. There was an increased incidence and degree of aggregates of pigmented Kupffer cells and macrophages in the livers of male and female dogs and an increased incidence of pigmented macrophages in the spleen of male dogs treated with 500 ppm or 185 ppm when compared to control male dogs.
- The initial appeared to be increased pigmentation of Kupffer cells and /or macrophages with Perls’ positive material, possibly reflecting increased iron metabolism and turnover. These changes were evident at all dosages in the liver, and for males at 185 or 500 ppm in the spleen. At 185 and 500 ppm, more marked associated changes were seen in the liver, chiefly hepatocyte degeneration and inflammatory cell infiltration. The only change identified at the low dose that could be possibly related to treatment, was aggregates of pigmented Kupffer cells and macrophages in one male and one female.

Effect levels

1

Dose descriptor:

LOAEL

Effect level:

ca. 185 ppm

Sex:

male/female

Basis for effect level:

other: = 6.6 mg ziram/kg bw/day = 6.2 mg SDDC (a.s.)/kg bw/day = 14.9 mg SDDC (41.44% solution as supplied)/kg bw/day, based on decrease in body weight gain, albumin and histopathology in spleen and liver.

2

Dose descriptor:

NOAEL

Effect level:

ca. 50 ppm

Sex:

male/female

Basis for effect level:

other: = 1.6 mg ziram/kg bw/day = 1.5 mg SDDC (a.s.)/kg bw/day = 3.6 mg SDDC (41.44%)/kg bw/day

Target system / organ toxicity

Critical effects observed:

not specified

Any other information on results incl. tables

Table A6_5-1.         Results of chronic toxicity study
Parameter	Control		50 ppm		185 ppm		500 ppm		Dose-response +/–
	♂	♀	♂	♀	♂	♀	♂	♀	♂	♀
Mortality								1	–	–
Body weight gain						↓ 68%		↓ 81%	–	+
Clinical chemistry
Albumin				↓ 12%		↓ 16%	↓ 13%	↓ 16%	–	–
Cholesterol							↑ 51%		–	–
T3							↑ 33%		–	–
Organ weight							2/4
Liver							↑ 16%		+	–
Histopathology of liver
Foci degenerated hepatocytes	1/4	3/4	2/4	0/4	2/4	3/4	3/4	2/3	+	–
Aggregates of pigmented Kuppfer cells	0/4	0/4	1/4	1/4	2/4	3/4	3/4	2/3	+	–
Histopathology of spleen
Increased pigmented macrophages	1/4	2/4	1/4	2/4	3/4	2/4	3/4	3/3	–	–
↓ ↑: statistical significance