1,3-diphenyl-2-thiourea

Long-term toxicity to aquatic invertebrates

Link to relevant study record(s)

Reference

Endpoint:

long-term toxicity to aquatic invertebrates

Type of information:

experimental study

Adequacy of study:

key study

Study period:

2015

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

OECD Guideline 211 (Daphnia magna Reproduction Test)

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Analytical monitoring:

yes

Details on sampling:

Samples for analysis were taken from all test concentrations and the control on 4 occasions throughout the test, on fresh (D0, D7, D13 and D20) and old solutions (D1, D8, D14, D21) for each occasion. Samples were taken from the test vessels and filtered through 0.45 µm filters in order to remove any solid content. Samples were analysed immediately after collection.

Vehicle:

no

Details on test solutions:

No specificity. A typical daphnia medium was used.

Test organisms (species):

Daphnia magna

Details on test organisms:

The test organisms used for this study was Daphnia magna Straus (Cladocera, Crustacea), clone 5, bred within the laboratory by acyclical parthenogenesis in a synthetic medium. The neonates used were less than 24h old at test initiation (selected by filtration) and were not first brood progeny. Test animals were fed a diet of 0.1 - 0.2 mg of carbon per daphnid per day, in the form of a suspension of the algal strains Chlorella vulgaris (25%) and Pseudokirchneriella subcapitata (75%), except during the initial three days of culture when a slightly lower ration was given.

Test type:

semi-static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

21 d

Post exposure observation period:

None.

Hardness:

170 - 180 as mg/L CaCO3

Test temperature:

19.2-20.1°C (min-max)

pH:

7.4 - 8.6 (min-max)

Dissolved oxygen:

8.5 - 10.3 mg/L (min-max)

Salinity:

Freshwater.

Nominal and measured concentrations:

Nominal: 0 ; 0.05 ; 0.15 ; 0.49 ; 1.53 ; 5 mg/L.
Concentrations were measured in all treatments in new and old media four times. All concentrations remained between 80 and 120% of the nominal concentration. Therefore, nominal concentrations were used for statistical analysis of the results.

Details on test conditions:

TEST SYSTEM
- Test vessel: tubes
- Material, size, headspace, fill volume: clear glass tubes (120 mL capacity), stoppered with cellulose bungs to minimise evaporation and dust.
- Aeration: None
- Semi-static: daily renewal, including weekends
- No. of organisms per vessel: 1
- No. of vessels per concentration (replicates): 10
- No. of vessels per control (replicates): 10

OTHER TEST CONDITIONS
- Adjustment of pH: None
- Photoperiod: 16L:8D
- Light intensity: 800 lux

EFFECT PARAMETERS MEASURED
- Number of dead parents per day
- Number of living neonates par day
- Age at first brood

Reference substance (positive control):

no

Duration:

21 d

Dose descriptor:

NOEC

Effect conc.:

0.15 mg/L

Nominal / measured:

nominal

Conc. based on:

act. ingr.

Basis for effect:

reproduction

Duration:

21 d

Dose descriptor:

NOEC

Effect conc.:

1.56 mg/L

Nominal / measured:

nominal

Conc. based on:

act. ingr.

Basis for effect:

immobilisation

Duration:

21 d

Dose descriptor:

NOEC

Effect conc.:

>= 5 mg/L

Nominal / measured:

nominal

Conc. based on:

act. ingr.

Basis for effect:

other: age at first brood

Details on results:

All test solutions appeared clear and colourless. No precipitation of test item nor undissolved particles were observed. Test item concentrations remained between 80% and 120% of the nominal concentrations in each treatment group for each sampling time (both new ans old). Based on these results, the exposure concentrations used for statistical analysis were based on the nominal concentration.
The number of immobile adults Daphnia magna recorded during the reproduction test was 1 (10%) at 0.05 mg/L, 2 (20%) at 1.56 mg/L and 10 (100%) at 5 mg/L of test item. There were no immobile Daphnia magna parent in the control group or in the 0.15 or 0.49 mg/L treated groups.
The numbers of offspring produced for each concentration (0 ; 0.05 ; 0.15 ; 0.49 ; 1.56 ; 5 mg/L) during the test were respectively 105.5, 96.4, 90.6, 88.5, 2.8 and 0 living neonates per living parent at the test of the test (Table 1).
Temperature was maintained at 20 ± 1°C (measured temperatures: min. 19.2, max. 20.1°C and mean: 19.6°C).

Results with reference substance (positive control):

None.

Reported statistics and error estimates:

Nominal concentrations of test item in the test solutions were used in the estimation of ECx and NOEC/LOEC values. Analysed variables were number of living neonates produced per living parent at the end of the test, parent immobilisation and mean time to first brood. All statistical analysis were conducted using the Software ToxRat 2.10.

Table 1: parent immobilization and mean number of living neonate produced per surviving parents at the end of the test for each concentration tested (expressed as geometric means).

Concentrations (mg/L)	Control	0.05	0.15	0.49	1.56	5
Mean number of neonates	105.5	96.4	90.6	88.5	2.8	---
Parent immobilization (%)	0	10	0	0	20	100

 

Table 2: mean number of neonates (living and dead), eggs and dead parent per day

 

		J6	J7	J8	J9	J10	J11	J12	J13	J14	J15	J16	J17	J18	J19	J20	J21
0	Number of liv. neo	0	0	35	97	17	72	148	0	25	143	79	20	96	195	0	128
	Number of dead neo.	0	0	2	13	4	4	5	0	12	1	0	5	0	1	0	0
	Number of egg	0	0	0	2	1	0	6	0	0	2	0	0	1	4	0	0
	Number of dead	0	0	0	0	0	0	0	0	0	0	0	0	0	0	0	0
0,05	Number of liv. neo	0	0	39	79	20	55	92	66	0	162	42	0	99	108	69	39
	Number of dead neo.	0	0	3	8	2	3	5	4	0	2	0	0	0	3	2	0
	Number of egg	0	0	0	0	0	0	1	6	0	4	1	0	1	1	0	0
	Number of dead	0	0	0	0	1	0	0	0	0	0	0	0	0	0	0	0
0,15	Number of liv. neo	0	0	38	73	0	47	168	0	0	197	56	0	121	206	0	0
	Number of dead neo.	0	0	10	35	0	4	28	0	0	4	14	0	0	13	0	0
	Number of egg	0	0	5	7	0	4	10	0	0	9	2	0	0	9	0	0
	Number of dead	0	0	0	0	0	0	0	0	0	0	0	0	0	0	0	0
0,49	Number of liv. neo	0	0	37	63	0	71	112	19	24	154	27	0	113	184	0	81
	Number of dead neo.	0	0	21	18	0	9	11	20	0	2	17	0	2	14	0	0
	Number of egg	0	0	3	11	0	5	13	6	3	31	12	0	5	16	0	0
	Number of dead	0	0	0	0	0	0	0	0	0	0	0	0	0	0	0	0
1,56	Number of liv. neo	0	0	0	0	0	0	0	0	0	10	0	0	0	12	0	0
	Number of dead neo.	0	0	0	0	0	0	3	0	0	6	0	0	0	4	0	0
	Number of egg	0	0	0	15	0	0	6	0	1	8	0	0	0	13	0	0
	Number of dead	1	0	0	0	0	0	0	0	0	0	0	0	0	0	0	0
5	Number of liv. neo	0	0	0	0	0	0	0	0	0	0	0	0	0	0	0	0
	Number of dead neo.	0	0	0	0	0	0	0	0	0	0	0	0	0	0	0	0
	Number of egg	0	0	0	0	0	0	0	0	0	0	0	0	0	0	0	0
	Number of dead	0	4	0	1	5	0	0	0	0	0	0	0	0	0	0	0

 

Table 3: total number of neonates (living and dead), eggs and dead parents

0	Total liv. neo	1055
	Total dead neo.	47
	Total egg	16
	Total dead	0
0,05	Total liv. neo	870
	Total dead neo.	32
	Total egg	14
	Total dead	1
0,15	Total liv. neo	906
	Total dead neo.	108
	Total egg	46
	Total dead	0
0,49	Total liv. neo	885
	Total dead neo.	114
	Total egg	105
	Total dead	0
1,56	Total liv. neo	22
	Total dead neo.	13
	Total egg	43
	Total dead	2
5	Total liv. neo	0
	Total dead neo.	0
	Total egg	0
	Total dead	10

Validity criteria fulfilled:

yes

Conclusions:

The toxicity of 1,3-diphenyl-2-thiourea was tested on Daphnia magna reproduction according to the OECD 211 guideline. The lowest NOEC was 0.15 mg/L.

Executive summary:

This study was designed to determine the effects of 1,3 -diphenyl-2 -thiourea on Daphnia magna reproduction and survival in a 21 days test according to the OECD 211 Guideline. The total test period was 21 days; all test solutions (including control) were renewed every day (including "weekend" periods). Ten replicate test vessels were prepared for the control and the test concentration. A single juvenile Daphnia magna (<24 hours old selected by filtration) was added to each test vessel. Each day, parental animals were transferred into freshly prepared test media. Dead parents were noted and discarded. All produced juveniles were counted every day. Chemical analysis of test samples confirmed the stability of the substance over a 24-hour test period. Based on these results, the exposure concentrations were based on the nominal concentration. NOEC and LOEC values on day 21 were determined as follows:

NOEC for mean number of neonate produced per parent alive at the end of the test: 0.15 mg/L

NOEC for mobility: 1.56 mg/L

NOEC for age at first reproduction: > 5 mg/L.

Description of key information

The chronic toxicity was assessed according to the OECD 211 guideline.
21d-NOEC = 0.15 mg/L.

Key value for chemical safety assessment

Fresh water invertebrates

Fresh water invertebrates

Effect concentration:

0.15 mg/L

Additional information

This study was designed to determine the effects of 1,3 -diphenyl-2 -thiourea on Daphnia magna reproduction and survival in a 21 days test according to the OECD 211 Guideline. The total test period was 21 days; all test solutions (including control) were renewed every day (including "weekend" periods). Ten replicate test vessels were prepared for the control and the test concentration. A single juvenile Daphnia magna (<24 hours old selected by filtration) was added to each test vessel. Each day, parental animals were transferred into freshly prepared test media. Dead parents were noted and discarded. All produced juveniles were counted every day. Chemical analysis of test samples confirmed the stability of the substance over a 24-hour test period. Based on these results, the exposure concentrations were based on the nominal concentration. NOEC and LOEC values on day 21 were determined as follows:

NOEC for mean number of neonate produced per parent alive at the end of the test: 0.15 mg/L

NOEC for mobility: 1.56 mg/L

NOEC for age at first reproduction: > 5 mg/L.