Di(benzothiazol-2-yl) disulphide

Sediment toxicity

Link to relevant study record(s)

Reference

Endpoint:

sediment toxicity: long-term

Type of information:

experimental study

Adequacy of study:

key study

Study period:

February 2017 - March 2017

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

OECD Guideline 218 (Sediment-Water Chironomid Toxicity Test Using Spiked Sediment)

GLP compliance:

yes (incl. QA statement)

Analytical monitoring:

yes

Remarks:

Analysis with HPLC with MS/MS detection.

Details on sampling:

Sample preparation water: Samples were 1:1 diluted with tetrahydrofuran/acetonitrile (2:8, v,v) + 0.1 % formic acid after defrosting.
Sample preparation sediment: Samples were extracted with tetrahydrofuran/acetonitrile (2:8, v,v) + 0.1 % formic acid by shaking for 2 hours.

Vehicle:

no

Test organisms (species):

Chironomus riparius

Details on test organisms:

Chironomus riparius (Meigen), 1st instar larvae

Study type:

laboratory study

Test type:

static

Water media type:

freshwater

Type of sediment:

artificial sediment

Limit test:

no

Duration:

28 d

Exposure phase:

total exposure duration

Hardness:

Characteristics of the M4 medium used:
15.2 and 19.0 °dH, i.e. between 271 and 339 mg/L as CaCO3
(water hardness was measured before introducing the test organisms and et the end of the test)

Test temperature:

19.5–21.0 °C (n=35; manual measurement in the test vessels)
19.4–20.5 °C (n=673; automatic measurement in a separate vessel)

pH:

pH of the overlying water in all test vessels: 7.8–8.2 (required 6-9 at the end of the test)

Dissolved oxygen:

Dissolved oxygen concentration in all test vessels at the end of the test: ≥81% (ASV)
required: at least 60% of the air saturation value (ASV)

Ammonia:

The ammonium content in the overlying water ranged from 0.75 to 1.12 mg/L at start and from 0.019 to 22.0 mg/L at the end of the test.

Conductivity:

Conductivity (deionised water) 10 µS/cm, in addition to dry sediment (30–50% of dry sediment)

Nominal and measured concentrations:

100, 50.0, 25.0, 12,5 and 6.25 mg/kg dry sediment plus a control

Reference substance (positive control):

no

Duration:

28 d

Dose descriptor:

EC10

Effect conc.:

31.9 mg/kg sediment dw

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

emergence rate

Duration:

28 d

Dose descriptor:

EC50

Effect conc.:

77.5 mg/kg sediment dw

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

emergence rate

Duration:

28 d

Dose descriptor:

NOEC

Effect conc.:

25 mg/kg sediment dw

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

emergence rate

Duration:

28 d

Dose descriptor:

LOEC

Effect conc.:

50 mg/kg sediment dw

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

emergence rate

Duration:

28 d

Dose descriptor:

NOEC

Effect conc.:

100 mg/kg sediment dw

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

development rate

Remarks:

maels and females, pooled

Duration:

28 d

Dose descriptor:

LOEC

Effect conc.:

> 100 mg/kg sediment dw

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

development rate

Remarks:

males and females, pooled

Key result

Duration:

28 d

Dose descriptor:

EC10

Effect conc.:

22 mg/kg sediment dw

Nominal / measured:

meas. (initial)

Conc. based on:

test mat.

Basis for effect:

emergence rate

Duration:

28 d

Dose descriptor:

EC50

Effect conc.:

53.4 mg/kg sediment dw

Nominal / measured:

meas. (initial)

Conc. based on:

test mat.

Basis for effect:

emergence rate

Duration:

28 d

Dose descriptor:

NOEC

Effect conc.:

17.2 mg/kg sediment dw

Nominal / measured:

meas. (initial)

Conc. based on:

test mat.

Basis for effect:

emergence rate

Duration:

28 d

Dose descriptor:

LOEC

Effect conc.:

34.4 mg/kg sediment dw

Nominal / measured:

meas. (initial)

Conc. based on:

test mat.

Basis for effect:

emergence rate

Duration:

28 d

Dose descriptor:

NOEC

Effect conc.:

68.9 mg/kg sediment dw

Nominal / measured:

meas. (initial)

Conc. based on:

test mat.

Basis for effect:

development rate

Remarks:

males and females, pooled

Duration:

28 d

Dose descriptor:

LOEC

Effect conc.:

> 68.9 mg/kg sediment dw

Nominal / measured:

meas. (initial)

Conc. based on:

test mat.

Basis for effect:

development rate

Remarks:

males and females, pooled

Details on results:

Measured initial concentrations were between 52.9 and 84.8% of the nominal concentrations based on the total test item measured in the test system. Mean measured initial concentrations were at 68.85% of the nominal concentrations.

Validity criteria fulfilled:

yes

Remarks:

Some of the control midges had emerged later than required in the guideline. Since, however, all control midges emerged, and 94% of the emerged midges had emerged by day 23, an impact on the integrity of this study can be excluded.

Conclusions:

No effects from Rubator MBTS on development rate (males, females and males and females pooled) were observed. The 28d-NOEC = 100 mg/kg dry sediment (nominal concentration) and 28d-LOEC = >100 mg/kg dry sediment (nominal concentration) were derived. Mean measured initial concentration were at 68.85% of the nominal concentration. Therefore, these results equal to a 28d-NOEC = 68.9 mg/kg dry sediment (mean measured initial concentration) and 28d-LOEC = >68.9 mg/kg dry sediment (mean measured initial concentration).
Effects were observed for the emergence ratio (males and females, pooled). Here, a 28d-NOEC = 25.0 mg/kg dry sediment (nominal concentration), 28d-LOEC = 50.0 mg/kg dry sediment (nominal concentration) and EC10 = 31.9 mg/kg dry sediment (nominal concentration) were derived. These results equal to a 28d-NOEC = 17.2 mg/kg dry sediment (mean measured initial concentration), 28d-LOEC = 34.4 mg/kg dry sediment (mean measured initial concentration) and EC10 = 22.0 mg/kg dry sediment (mean measured initial concentration).

Executive summary:

The lethal and sublethal effects of Rubator MBTS to the sediment-dwelling larvae of freshwater dipteran Chironomus riparius after 28 days was investigated according to OECD guideline 218. The nominal concentrations of 100, 50.0, 25.0, 12.5 and 6.25 mg/kg dry sediment were applied. Analysis was perfomed by using HPLC-MS/MS method. The endpoints emergence ratio (males and females, pooled) and the developmental rate (males, females and males and females pooled) were investigated. A clear concentration-response relationship was observed for the emergence ratio (males and females pooled) after 28 days of exposure. Based on nominal concentrations the 28d-NOEC = 25.0 mg/kg dry sediment, 28d-LOEC = 50.0 mg/kg dry sediment and the EC10 = 31.9 mg/kg dry sediment (basis of effect: emergence ratio) dry sediment was determined. Yet, the test showed no concentration-response relationship for the development rate after 28 days of exposure. Thus, a 28d-NOEC = 100 mg/kg dry sediment and 28d-LOEC = >100 mg/kg dry sediment (nominal concentrations, basis of effect: development rate; males, females and males and females pooled) was determined.

In order to express the biological results based on the mean measured initial concentrations the biological results were corrected by the factor of 0.6885.

The resulting ECx, NOEC and LOEC values are 28d-NOEC = 17.2 mg/kg dry sediment, 28d-LOEC = 34.4 mg/kg dry sediment and the 28d-EC10 = 22.0 mg/kg dry sediment (basis of effect emergence ratio) dry sediment was determined. Further, a 28d-NOEC = 68.9 mg/kg dry sediment and 28d-LOEC = >68.9 mg/kg dry sediment (basis of effect: development ratio, males and females pooled) was determined (ECT, 2017).

Description of key information

No effects from Rubator MBTS on development rate (males, females and males and females pooled) of chironomus riparius were observed according to OECD guideline 218 (ECT 2017). The 28d-NOEC = 100 mg/kg dry sediment and 28d-LOEC = >100 mg/kg dry sediment (nominal concentrations) were derived. Mean measured initial concentration were at 68.85% of the nominal concentration. Therefore, these results equal to a 28d-NOEC = 68.9 mg/kg dry sediment and 28d-LOEC = >68.9 mg/kg dry sediment (mean measured initial concentrations).

Effects were observed for the emergence ratio (males and females, pooled). Here, a 28d-NOEC = 25.0 mg/kg dry sediment, 28d-LOEC = 50.0 mg/kg dry sediment, 28d-EC50 = 77.5 mg/kg dry sediment and 28d-EC10 = 31.9 mg/kg dry sediment (nominal concentrations) were derived. These results equal to a 28d-NOEC = 17.2 mg/kg dry sediment, 28d-LOEC = 34.4 mg/kg dry sediment, 28d-EC50 = 53.4 mg/kg dry sediment and 28d-EC10 = 22.0 mg/kg dry sediment (mean measured initial concentrations).

Key value for chemical safety assessment

EC50 or LC50 for freshwater sediment:

53.4 mg/kg sediment dw

EC10, LC10 or NOEC for freshwater sediment:

22 mg/kg sediment dw

Additional information

28d-EC50 = 53.4 mg/kg sediment dry weight and 28d-EC10 = 22.0 mg/kg sediment dry weight are based on the mean measured initial concentration which equal to 28d-EC50 = 77.5 mg/kg sediment dry weight and 28d-EC10 = 31.9 mg/kg sediment dry weight nominal concentration. Basis for effect is the emergence ratio, males and females pooled (ECT, 2017).