Di-tert-butyl trisulphide

Short-term toxicity to aquatic invertebrates

Link to relevant study record(s)

Reference

Endpoint:

short-term toxicity to aquatic invertebrates

Type of information:

experimental study

Adequacy of study:

key study

Study period:

May 2000

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

guideline study with acceptable restrictions

Reason / purpose for cross-reference:

reference to same study

Qualifier:

according to guideline

Guideline:

OECD Guideline 202 (Daphnia sp. Acute Immobilisation Test)

Deviations:

no

GLP compliance:

yes

Analytical monitoring:

yes

Details on sampling:

Procedures: 100 mg of TPS 44 were introduced in 1 litre of dilution water, vigorously shaken at 30°C for 4 hours then at 20°C for 20 hours (preliminary assay) or 62 hours (main study). Daphnids were exposed to a concentration range of 0.073 to 0.270 mg/l forming a geometric progression with a factor of 1.3. After 24 hours exposure a count of immobile Daphnia was carried out and another count was taken 48 hours after the start of the test. After decantation, the saturated solution was filtered on a 0.22µm filter. pH and dissolved oxygen were measured in the highest concentration and the control at the start of the test and in all concentrations at the end of the test.

Vehicle:

not specified

Details on test solutions:

The saturated stock solution was diluted using ultrapure water to produce concentrations ranging from 13.5 - 50% (vol). Concentrations were then produced in a geometric progression with a ratio of 1.3. The concentrations of the test substance were maintained to within 80% of the initial concentration throughout the duration of the test. Dilution water was prepared in the laboratory using pure water and salts according to ISO 6341.

Test organisms (species):

Daphnia magna

Details on test organisms:

Strain: Daphnia magna straus strain 5 or strain A. Source/supplier: Breeding colony was realized in the laboratory, organisms are selected by sieving and held in Elendt M4 media. Breeding method: Not available. Age: Less than 24 hours. Feeding: Microscopic algae Raphidocelis subcapitata. Pretreatment: No. Feeding during test: No. Control group: Yes.

Test type:

static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

48 h

Post exposure observation period:

No data reported

Hardness:

According to ISO 6341 medium

Test temperature:

Test temperature: 19.5 +/-1°C.

pH:

7.75 - 7.84

Dissolved oxygen:

9.0 - 9.7 mg/l.

Salinity:

According to ISO 6341 medium

Nominal and measured concentrations:

Nominal: 13.5 - 50 (volume saturated). Nominal concentrations: 13.5, 17.5, 22.8, 29.6, 38.5, 50 % saturated solution volume. Initial measured concentrations: 0.073 - 0.270 mg/l (extrapolated from measured concentrations). Daphnids were exposed to a concentration range of 0.073 to 0.270 mg/l forming a geometric progression with a factor of 1.3.

Details on test conditions:

The test was conducted in darkness in tightly closed 120 ml vessels, with 5 organisms per vessel and 4 replicates per concentration.

Reference substance (positive control):

yes

Remarks:

potassium dichromate

Duration:

24 h

Dose descriptor:

EC50

Effect conc.:

> 0.27 mg/L

Nominal / measured:

not specified

Conc. based on:

not specified

Basis for effect:

not specified

Remarks on result:

other: no data available

Duration:

48 h

Dose descriptor:

EC50

Effect conc.:

0.24 mg/L

Nominal / measured:

not specified

Conc. based on:

not specified

Basis for effect:

not specified

Remarks on result:

other: no data available

Details on results:

No data reported

Results with reference substance (positive control):

24 hour EC50: 1.5 mg/l

Reported statistics and error estimates:

Confidence intervals: 24 hour EC50: not determined; 48 hour EC50: 0.16 - 21.

Table 1: % of immobilisation in each treatment after 24h and 48h exposure to the test substance.

Mean measured concentration (mg/L)	Immobilisation %
	24 h	48 h
0	0	0
<DL	0	20
<DL	5	10
<DL	0	35
0.16	10	40
0.21	5	35
0.27	30	60

Validity criteria fulfilled:

yes

Conclusions:

In an ecotoxicity test using Daphnia magna the 24 hour EC50 for polysulfides, di-tert-butyl was > 0.27 mg/l and the 48 hour EC50 was 0.24 mg/l.

Executive summary:

Acute toxicity of TPS44 to Daphnia magna was determined according to OECD TG 202 protocol following GLP. Daphnids were exposed to a graded series of concentrations up to TPS44 water solubility limit (range from 0.073 to 0.270 mg/L with a 1.3 spacing factor). Static exposure was performed in quadruplicates (5 daphnids in each) for 48 hour at 19.5°C in the dark. Daphnid immobilisation was checked after 24 and 48 hour. The study was conducted in hermetically sealed flasks with no head-space. TPS 44 concentrations were determined at the beginning and the end of the test in all treatments. Toxicity was calculated according to the measured concentrations. 48h-EC50 was 0.24 mg/L.

Description of key information

In an ecotoxicity test using Daphnia magna the 24 hour EC50 for polysulfides, di-tert-butyl is > 0.27 mg/l and the 48 hour EC50 is 0.24 mg/l.

Key value for chemical safety assessment

Fresh water invertebrates

Fresh water invertebrates

Effect concentration:

0.24 mg/L

Additional information

Thiebaud (2000) is a 48 -hour, static, freshwater, GLP-compliant study on Daphnia magna with analytical monitoring, following OECD TG 202. The study is considered reliable and fully adequate for assessment. The EC50 result for aquatic invertebrates of 0.24 mg/l indicates that polysulfides, di-tert-bu would be 'very toxic to aquatic organisms'.