Disulfiram

Toxicity to soil macroorganisms except arthropods

Link to relevant study record(s)

Reference

Reference 1

Endpoint:

toxicity to soil macroorganisms except arthropods: short-term

Type of information:

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

Adequacy of study:

key study

Study period:

22 November 1991 - 16 January 1992

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: see 'Remark'

Remarks:

GLP - Guideline study, tested with the source substance thiram (CAS No. 137-26-8). In accordance to the ECHA guidance document “Practical guide 6: How to report read-across and categories (March 2010)”, the reliability was changed from RL1 to RL2 to reflect the fact that this study was conducted on an read-across substance

Qualifier:

according to guideline

Guideline:

OECD Guideline 207 (Earthworm, Acute Toxicity Tests)

GLP compliance:

yes (incl. QA statement)

Remarks:

The Department of Health and Social Security of the Government of the United Kingdom

Analytical monitoring:

no

Vehicle:

no

Test organisms (species):

Eisenia fetida

Animal group:

annelids

Details on test organisms:

TEST ORGANISM
- Common name: Earthworm
- Source: Monkfield aquatics, Bourne, Cambridgeshire
- Age at test initiation (mean and range, SD): not reported
- Weight at test initiation (mean and range, SD): 0.40 g (SD = 0.08 g)


ACCLIMATION
- Acclimation period: not reported
- Acclimation conditions: Worms were acclimatised in shallow containers of approximately 20 L volume at 20 +/- 2 °C and were lighted with 400 – 800 Lux. The substrate consisted of 50 % peat and 50 % horse manure. The pH value of the medium was adjusted to pH 6 – 7 by addition of calcium carbonate.

Study type:

laboratory study

Substrate type:

artificial soil

Limit test:

yes

Total exposure duration:

14 d

Test temperature:

21°C

pH:

5.6 – 6.0 at day 0
5.6 – 7.0 at day 14

Moisture:

30 – 37 % at day 0
27 - 30 % at day 14

Details on test conditions:

TEST SYSTEM
- Test container (material, size): 1 L glass beakers covered by plastic film with ventilation holes.
- Amount of soil or substrate: Per test beaker, 500 g dry artificial soil
- No. of organisms per container (treatment): 10
- No. of replicates per treatment group: 4
- No. of replicates per control: 4


SOURCE AND PROPERTIES OF SUBSTRATE (if soil)
- Composition: - 10 % Sphagnum moss peat
- 20 % Kaolinite clay
- 69 % Industrial quartz sand
- ca. 1 % calcium carbonate (CaCO3)
- Organic carbon (%): not reported
- Maximum water holding capacity (in % dry weigth): not reported


OTHER TEST CONDITIONS
- Photoperiod: Continuous light
- Light intensity: 650 Lux


EFFECT PARAMETERS MEASURED: Mortality: The number of dead adult worms was determined 7 days after exposure and at the end of the test for each concentration and for the control.
Biomass: Individual worms were weighed at test start and at test end.
Room temperature and light intensity were measured daily. Soil moisture content and pH were determined at test start and at test end.


VEHICLE CONTROL PERFORMED: no

Nominal and measured concentrations:

The nominal concentrations were specified in a previous range-finding test and were as follow: 56.25, 112.5, 225, 450, 900 and 1800 mg/kg soil (dw).
The reference substance was tested under the following concentrations: 5.6, 10, 18, 32 and 56 mg chloroacetamide/kg.

Reference substance (positive control):

yes

Remarks:

chloroacetamide

Duration:

14 d

Dose descriptor:

LC50

Effect conc.:

540 mg/kg soil dw

Nominal / measured:

nominal

Conc. based on:

act. ingr.

Basis for effect:

mortality

Remarks on result:

other: 460-630

Duration:

14 d

Dose descriptor:

NOEC

Effect conc.:

225 mg/kg soil dw

Nominal / measured:

nominal

Conc. based on:

act. ingr.

Basis for effect:

mortality

Duration:

14 d

Dose descriptor:

LC0

Effect conc.:

112.5 mg/kg soil dw

Nominal / measured:

nominal

Conc. based on:

act. ingr.

Basis for effect:

mortality

Details on results:

The LC50 was 540 mg a.s./kg soil (dw) (95 % confidence limits = 460 – 630 mg/kg soil (dw)).

Results with reference substance (positive control):

The LC50 value for chloroacetamide was 15 mg/kg. This value is within the upper (35 mg/kg) and lower (12.0 mg/kg) warning limits.

Validity criteria fulfilled:

yes

Conclusions:

Validity criteria according to the OECD guideline 207 are fulfilled, test results can be considered reliable

Executive summary:

Materials and methods: The objective of this study was the estimation of the acute toxicity of thiram to the earthworm, Eisenia fetida. 40 earthworms each were exposed to a range of concentrations (56.25, 112.5,225, 450, 900 and 1800 mg/kg dry weight of soil) of the test item in soil over a 14 day period according to OECD guideline 207. Mortality and behaviour were assessed after 7 and 14 days and the LC50 (median lethal concentration) estimated. The biomass was measured at the start and at the end of the study.

Chloroacetamide was used as reference item as recommended for acute earthworm toxicity tests.

Results and discussion: 3 earthworms (8 %) died in the control. 1 worm (3 %) was found dead at the lowest concentration tested (56.25 mg a.s./kg soil (dw)) and at 225 mg/kg soil (dw). No mortality occurred in the 112.5 mg/kg soil (dw) treatment. At the concentrations of 450, 900 and 1800 mg/kg soil (dw) 48 %, 75 % and 100 % mortality was observed, respectively.
In the test with the reference substance chloroacetamide, no mortality was observed at the two lowest test levels. At 18, 32 and 56 mg/kg, 80, 100 and 100 % of the worms died.

There were no observed behavioural reactions to exposure in the controls and all the remaining test groups.

Statistical analysis of variance was carried out on the worm weight data. No significant differences (p ≥ 0.05) were observed between the control and the 5625, 112.5, 225, 450, 900 and 1800 mg/kg test groups in terms of weight at Day 0. On Day 14 no significant differences (p ≥ 0.05) were observed between the control and the 56.25, 112.5 and 225 mg/kg test groups. The data obtained from the remaining test groups were not included in the analysis due to significant mortalities being observed within these groups.

Reference 2

Endpoint:

toxicity to soil macroorganisms except arthropods: long-term

Data waiving:

other justification

Justification for data waiving:

other:

Description of key information

NOEC (14 d) = 225 mg a.i./kg dw soil (Eisenia fetida)

Additional information

No data on toxicity of disulfiram to soil macroorganisms (CAS No. 97 -77 -8) were available. Therefore, a conclusion based on analogue approach had to be drawn. The toxic effects of tetramethylthiuram disulfide (CAS No.137-26-8), substance structurally and composition related to tetraethylthiuram disulfide, in Eisenia fetida were investigated in one study (Handley, 1992). This test was conducted according to OECD Guideline No. 207: Earthworm, Acute Toxicity Test (1984), under GLP conditions. After 14 days exposure to the test item in artificial soil, significant effects on survival of Eisenia fetida were observed at all concentrations tested except for the two lowest ones, resulting in a NOEC of 225 mg a.i./kg dw soil.

Long-term toxicity testing is not deemed necessary considering the expected rapid degradation of disulfiram in soil (half-life < 10 days).