1,3-diiodopropane

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:

June - July 2020

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

OECD Guideline 202 (Daphnia sp. Acute Immobilisation Test)

Version / remarks:

April 2004

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Analytical monitoring:

yes

Remarks:

see below

Details on sampling:

Sample preparation: 6 g NaCl was added to 100 mL of a solution in M4 medium (Blank control / 2.76 / 6 / 13.2 mg/L nominal); then, the solution was extracted two times with the dichloromethane (4 mL and 4 mL), the organic phase was collected into a 10 mL flask, after drying with Na2SO4. The flask was filled up to 10 mL with dichloromethane after addition of 500 µL ISTD (internal standard) solution (100 mg/L in dichloromethane) and the solution was measured via GC/MSD.
2 g NaCl was added to 20 mL of a solution in M4 medium (27 / 60 mg/L nominal); then, the solution was extracted two times with the dichloromethane (4 mL and 4 mL), the organic phase was collected into a 10 mL flask, after drying with Na2SO4. The flask was filled up to 10 mL with dichloromethane after addition of 500 µL ISTD (internal standard) solution (100 mg/L in dichloromethane) and the solution was measured via GC/MSD. On each sampling day, validity of calibration was controlled by measuring QC samples (10 mg/L). At the start and the end of the 2nd experiment, the mean recovery rate of the QC sample lay inside the demanded range (101.1 % and 102.5 %) and was not taken into account.

Vehicle:

no

Details on test solutions:

Based on further pre-tests as already described in Study Plan Amendment No. 1, a saturated solution was prepared for the test. This was done by mixing the real load of 596.472 mg/L with the corresponding amount of dilution water and stirring vigorously for 24 hours. Afterwards, the solution was centrifuged (10 min, 4500 rpm). The lower treatments (2.76 / 6 / 13.2 / 27.6 / 60 mg/L nominal) were prepared by dilution of this saturated solution with dilution water.
Positive Control: Potassium dichromate K2Cr2O7 (CAS No. 7778-50-9) was used as positive control in a current reference study (202005R201). The 24h-EC50 value was determined as 2.01 mg/L. The value was within the requested range for the 24h-EC50 between 0.6 - 2.1 mg/L of potassium dichromate K2Cr2O7 as specified in the OECD guideline.

Test organisms (species):

Daphnia magna

Details on test organisms:

Test System Specification
Species: Daphnia magna
Authority: STRAUS
Strain: Berlin (origin Umweltbundesamt Berlin; in-house breeding since 27. September 2007)
Sex: female
Age: between 0 and 24 hours
Animal Husbandry: Daphnia magna is bred in the LAUS GmbH throughout the year. The animals are kept for the use in toxicity tests. They multiply by parthenogenesis, thus being genetically identical. The keeping is performed similar to the method described in the OECD guideline, following SOP 115 002 01.
Vessels: preserving glasses, nominal volume 2 L
Medium: M4-Medium (recipe of ELENDT)
Food: green algae (Desmodesmus subspicatus)
Medium renewal: twice a week
Photo period: 16/8 hours, using neon tubes
Temperature: 20 ±2 °C
Dilution Water (M4 Medium): Deionized water with an enrichment of certain minerals was used in the test. The minerals which are added comply to the composition M4 (Annex 4: Composition of Dilution Water (M4)) derived by ELENDT as stated in the OECD-Guideline.
Test Vessels: Beakers, glass, nominal volume 50 mL.

Test type:

static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

48 h

Post exposure observation period:

none

Test temperature:

20.1 – 21.0 °C

pH:

7.6 at start and 7.2 - 7.4 after 48 hours

Dissolved oxygen:

7.8 - 8.7 during exposure at all concentrations

Nominal and measured concentrations:

2.76 / 6 / 13.2 / 27.6 / 60 mg/L (nominal concentration)

Details on test conditions:

see below

Reference substance (positive control):

yes

Remarks:

K2Cr2O7 (CAS No. 7778-50-9)

Duration:

24 h

Dose descriptor:

EC50

Effect conc.:

2.22 mg/L

Nominal / measured:

meas. (geom. mean)

Conc. based on:

test mat. (dissolved fraction)

Basis for effect:

mobility

Remarks on result:

other: 95% Confidence limit interval: 1.81 mg/L – 2.72 mg/L

Duration:

48 h

Dose descriptor:

EC50

Effect conc.:

1.89 mg/L

Nominal / measured:

meas. (geom. mean)

Conc. based on:

test mat. (dissolved fraction)

Basis for effect:

mobility

Duration:

48 h

Dose descriptor:

NOEC

Effect conc.:

1 mg/L

Nominal / measured:

meas. (geom. mean)

Conc. based on:

test mat. (dissolved fraction)

Basis for effect:

mobility

Duration:

48 h

Dose descriptor:

LOEC

Effect conc.:

2.22 mg/L

Nominal / measured:

meas. (geom. mean)

Conc. based on:

test mat. (dissolved fraction)

Basis for effect:

mobility

Details on results:

The second experiment was performed using 5 concentrations ranging from 2.76 to 60 mg/L nominal concentration. For each test concentration and the blank control, 20 daphnia were exposed to the test item for 48 hours in a static test system. After 24 and 48 hours, the immobilised daphnia were counted. Three concentrations showed toxicity between 90 % and 100 % immobilisation, following 48 hours exposure. None of the animals was immobilised in the blank control.
Potassium dichromate K2Cr2O7 (CAS No. 7778-50-9) was used as positive control in a current reference study to assure that the test conditions are reliable.
The test solutions were stirred for 24 hours to guarantee that a sufficient amount of test item has gone into solution. At the start and at the end of the test, the content of the test item in the test solutions was determined using GC/MSD-Method. The measured concentrations lay between 16 % and 19 % of the nominal concentrations at the beginning of the test and between 17 % and 18 % of the nominal concentrations at the end of the test. Therefore, the determination of the results was based on the geometric mean of the measured concentrations (see OECD 202 (§ 23)).
No observations were made which might cause doubts concerning the validity of the study outcome. All validity criteria were met. The result of the test is considered valid.

Results with reference substance (positive control):

Potassium dichromate K2Cr2O7 (CAS No. 7778-50-9) was used as positive control in a current reference study (202005R201). The 24h-EC50 value was determined as 2.01 mg/L. The value was within the requested range for the 24h-EC50 between 0.6 - 2.1 mg/L of potassium dichromate K2Cr2O7 as specified in the OECD guideline.

Reported statistics and error estimates:

The estimation of the biological results was accomplished using the software ToxRat® Professional, version 3.3.0. The details of calculation are stated in the original test report.

Immobility: In the blank control and the treatments 2.76 and 6 mg/L, none of the daphnia was immobilised. The determined immobility is listed in the following table 1.

Table 1: Immobility

Nominal Conc.	Immobility 24 hours					Immobility 48 hours
in mg/L	absolute in %					absolute in %
Blank control	0	0	0	0	0	0	0	0	0	0
2.76	0	0	0	0	0	0	0	0	0	0
6	0	0	0	0	0	0	0	0	0	0
13.2	5	1	4	2	60	5	4	5	4	90
27.6	5	5	4	4	90	5	5	5	5	100
60	5	5	5	5	100	5	5	5	5	100

 

pH and O2: The pH values and the concentration of dissolved oxygen in the treatments and the blank control are given in the following table 2.

Table 2: pH and O2-values

Nominal Conc. [mg/L]	pH		O2-Concentration in mg/L
	0 h	48 h	0 h	48 h
Blank control	7.6	7.2	8.6	8.0
2.76	7.6	7.2	8.7	8.7
6	7.6	7.3	8.7	8.7
13.2	7.6	7.3	8.7	8.5
27.6	7.6	7.4	8.7	8.2
60	7.6	7.4	8.7	7.8

 

Analytical Determinations

At the start and at the end of the test, the content of the test item in the test solutions was determined using GC/MSD-Method. The measured concentrations lay between 16 % and 19 % of the nominal concentrations at the beginning of the test and between 17 % and 18 % of the nominal concentrations at the end of the test. Therefore, the determination of the results was based on the mean of the measured concentrations (see OECD 202 (§ 23)).

Table 3: Measured Concentrations at 0 h 

NominalConc.	Intensity	Measured Conc.	QC recovery and mean ac-curacy recovery	Dilution factor	Calculated Conc.	Mean Cal-culated Conc.
mg/L	--	mg/L	%	--	mg/L	mg/L
QC sample (10 µg/L)	50280	37286	98.8	--	10.00	--
	48857	36063	99.2	--	10.00
Blank control	14	37148	--	--	0.41	0.41
	14	37765	--	--	0.41
2.76	20891	36865	--	0.1	0.46	0.46
	21127	37392	--	0.1	0.46
6	49929	38870	--	0.1	0.95	0.94
	52475	41091	--	0.1	0.94
13.2	111284	35193	--	0.1	2.06	2.05
	109160	35021	--	0.1	2.03
27.6	41527	35495	--	0.5	4.36	4.40
	44121	36960	--	0.5	4.44
60	134504	38263	--	0.5	11.25	11.30
	125671	35345	--	0.5	11.35
QC sample (10 µg/L)	50581	35730	103.1	--	10.00	--
	53119	37498	103.2	--	10.00

LOQ = 0.1 mg/L

Mean recovery rate of the QC sample lay inside the demanded range (± 3 %) and was not taken into account.

 

Table 4: Measured Concentrations at 48 h

NominalConc.	Intensity	Measured Conc.	QC recovery and mean ac-curacy recovery	Dilution factor	Calculated Conc.	Mean Cal-culated Conc.
mg/L	--	mg/L	%	--	mg/L	mg/L
QC sample (10 µg/L)	48195	34131	102.9	--	10.00	--
	46533	34222	99.5	--	10.00
Blank control	7	39314	--	0.1	0.41	0.41
	--	34838	--	0.1	--
2.76	20959	35043	--	0.1	0.48	0.48
	20873	34881	--	0.1	0.48
6	50329	34140	--	0.1	1.07	1.08
	49948	33398	--	0.1	1.08
13.2	119467	32325	--	0.5	2.34	2.32
	131383	36477	--	0.5	2.29
27.6	41358	32533	--	0.5	4.69	4.71
	43038	33603	--	0.5	4.72
60	121165	36581	--	--	10.70	10.78
	121791	36121	--	--	10.86
QC sample (10 µg/L)	46424	32614	103.6	--	10.00	--
	46577	32667	103.8	--	10.00

LOQ = 0.1 mg/L

Mean recovery rate of the QC sample lay inside the demanded range (± 3 %) and was not taken into account.

 

Table 5: % of Nominal and Geometric Mean

Nominal Conc.	% of Nominal		Geometric Mean
mg/L	0 h	48 h	mg/L
Blank control	--	--	--
2.76	17	17	0.47
6	16	18	1.01
13.2	16	18	2.18
27.6	16	17	4.56
60	19	18	11.04

 

BIOLOGICAL RESULTS AND STATISTICS

The estimation of the biological results was accomplished using the software ToxRat® Professional, version 3.3.0.

 

The biological results are presented in the following table:

Table 6: Biological Results Test Item

Parameter	Value	95%-confidence interval
24h EC50	2.22 mg/L	1.81 mg/L – 2.72 mg/L
48h EC50	1.89 mg/L	n.d.
48h NOEC	1.00 mg/L	--
48h LOEC	2.20 mg/L	--

n.d.: not determined due to mathematical reasons or inappropriate data

 

VALIDITY

All validity criteria were fulfilled:

- Immobilisation in the controls may not exceed 10 %: Immobilisation in the controls was 0 %.

- The concentration of dissolved oxygen at the end of the test must be at least 3 mg/L: The lowest concentration of dissolved oxygen at the end of the test was 7.8 mg/L.

Hence, all validity criteria were fulfilled.

Validity criteria fulfilled:

yes

Conclusions:

In this OECD 202 study with Daphnia magna the following results were recorded: 24h-EC50 = 2.22 mg/L and 48h-EC50 = 1.89 mg/L

Executive summary:

Two experiments and one pre-test were performed. The 1st experiment was aborted, as no test item could be measured during the analytical determination at the start of the test. Therefore, an additional pre-test was performed to determine how the substance can best be brought into solution and a second experiment was conducted. The implementation and the results of the pre-test were stated in the original test report document.

The second experiment was performed using 5 concentrations ranging from 2.76 to 60 mg/L nominal concentration. For each test concentration and the blank control, 20 daphnia were exposed to the test item for 48 hours in a static test system. After 24 and 48 hours, the immobilised daphnia were counted.

Three concentrations showed toxicity between 90 % and 100 % immobilisation. None of the animals was immobilised in the blank control.

Potassium dichromate K2Cr2O7 (CAS No. 7778-50-9) was used as positive control in a current reference study to assure that the test conditions are reliable.

The test solutions were stirred for 24 hours to guarantee that a sufficient amount of test item has gone into solution. At the start and at the end of the test, the content of the test item in the test solutions was determined using a GC/MSD-Method.

The measured concentrations lay between 16 % and 19 % of the nominal concentrations at the beginning of the test and between 17 % and 18 % of the nominal concentrations at the end of the test. Therefore, the determination of the results was based on the geometric mean of the measured concentrations (see OECD 202 (§ 23)).

The following results were determined for the test item 1,3-Diiodopropane (species: Daphnia magna): 48h-NOEC = 1.00 mg/L, 48h-LOEC = 2.20 mg/L, 24h-EC50 = 2.22 mg/L, 48h-EC50 = 1.89 mg/L.

Description of key information

In an OECD 202 study with Daphnia magna the following results were recorded for the test substance 1,3 -diiodopropane: 24h-EC50 = 2.22 mg/L and 48h-EC50 = 1.89 mg/L

Key value for chemical safety assessment

Fresh water invertebrates

Fresh water invertebrates

Effect concentration:

1.89 mg/L