Reaction products of sodium glucoheptonate with zinc sulfate and sodium hydroxide

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:

2016/05/19 - 2017/03/21

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)

GLP compliance:

yes (incl. QA statement)

Analytical monitoring:

yes

Details on sampling:

100 mL of test samples from each replicates were drawn and mixed together for each group at 0 and 48 h. The samples were divided into two equal portions. One portion (200 mL) was sent for test concentration analysis and the second portion (200 mL) was stored at -20+-5°C temperature till the study completion.

Vehicle:

no

Details on test solutions:

An amount of 1000 mg DABQUEL COMPLEX ZnP was transferred in 100 mL volumetric flask and the volume was made up to the mark with reconstituted water to obtain the nominal concentration of 10.0 mg/mL (stock A). Volumes of 247.5, 370.0, 555.0, 832.5 and 1250.0 µL from the stock A were taken and diluted to 250 mL with reconstituted water in respective glass beakers of 600 mL capacity to obtain the nominal test concentrations of 9.9, 14.8, 22.2, 33.3 and 50.0 mg DABQUEL COMPLEX ZnP/L, respectively.

Test organisms (species):

Daphnia magna

Details on test organisms:

TEST ORGANISM
- Source: Daphnids used for the study were cultured in the test facility. The master culture was procured from MicroBio Test Inc, Kleimoer 15, 9030 Mariakerke (Gent), Belgium.
- Age of parental stock: < 24h
- Feeding during test: no

ACCLIMATION
- Acclimation period: minimum of 48 h
- Acclimation conditions: same as test
- Type and amount of food:live algal cells (Pseudokirchneriella subcapitata)

METHOD FOR PREPARATION AND COLLECTION OF EARLY INSTARS OR OTHER LIFE STAGES
Freshly hatched daphnids were collected with the help of a micropipette and were used for the study.

Test type:

static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

48 h

Hardness:

190.4 mg/L as CaCO3

Test temperature:

20+-1°C

pH:

7.63 - 7.93

Dissolved oxygen:

8.40 - 8.91

Nominal and measured concentrations:

nominal 9.9, 14.8, 22.2, 33.3, 50 mg ZnP/L (measured active ingredient concentration was >80 % of nominal concentration)

Details on test conditions:

TEST SYSTEM
- Test vessel: glass beaker (600 mL capacity)
- No. of organisms per vessel: 5
- No. of vessels per concentration (replicates): 4
- No. of vessels per control (replicates): 4

TEST MEDIUM / WATER PARAMETERS
- Source/preparation of dilution water: The diluent water was aerated, prior to use, so that dissolved oxygen concentration has reached saturation. Reconstituted water was prepared by adding different nutrients to the distilled water.

OTHER TEST CONDITIONS
- Photoperiod: 16:8 (light:dark cycle)
- light intensity: 1310 - 1330 lux

RANGE-FINDING STUDY
- Test concentrations: 0, 0.1, 1, 10, 50, 100 mg ZnP/L
- Results used to determine the conditions for the definitive study: percent immobilisation were 0,0,0,0,100 and 100% for the respective concentraions

Reference substance (positive control):

yes

Remarks:

The test system was previously validated in the test facility using potassium dichromate as positive control.

Duration:

48 h

Dose descriptor:

NOEC

Effect conc.:

9.9 mg/L

Nominal / measured:

nominal

Conc. based on:

act. ingr.

Basis for effect:

mobility

Remarks on result:

other: measured active ingredient concentration was >80 % of nominal concentration

Duration:

48 h

Dose descriptor:

LOEC

Effect conc.:

14.8 mg/L

Nominal / measured:

nominal

Conc. based on:

act. ingr.

Basis for effect:

mobility

Remarks on result:

other: measured active ingredient concentration was >80 % of nominal concentration

Duration:

48 h

Dose descriptor:

EC100

Effect conc.:

50 mg/L

Nominal / measured:

nominal

Conc. based on:

act. ingr.

Basis for effect:

mobility

Remarks on result:

other: measured active ingredient concentration was >80 % of nominal concentration

Duration:

48 h

Dose descriptor:

EC50

Effect conc.:

24.9 mg/L

Nominal / measured:

nominal

Conc. based on:

act. ingr.

Basis for effect:

mobility

Remarks on result:

other: measured active ingredient concentration was >80 % of nominal concentration

Details on results:

The percent immobilisation observed at 24h were 0, 0, 0, 0 and 5 at the test concentrations of 9.9, 14.8, 22.2, 33.3 and 50 mg ZnP/L, respectively. No immobility was observed in any of the replicates of the control group.
The percent immobilisation observed at 48h were 0, 10, 50, 70 and 100 at the test concentrations of 9.9, 14.8, 22.2, 33.3 and 50 mg ZnP/L, respectively. No immobility was observed in any of the replicates of the control group.
At 24 h, No behavioural symptoms were observed in concentration 6 (50.0 mg/L). No immobility and behavioural symptoms were observed in concentration 5 (33.3 mg/L), concentration 4 (22.2 mg/L). Concentration 3 (14.8 mg/L), concentration 2 (9.9 mg/L) and control groups.
At 48 h, lethargy was observed in concentration 5 (33.3 mg/L), concentration 4 (22.2 mg/L), concentration 3 (14.8 mg/L). No immobility and behavioural symptoms were observed in concentration 2 (9.9 mg/L) and coontrol groups.
No signs of disease or stress, e.g., discoloration or unusual behaviour such as trapping at the surface of water were observed in any of the replicates of the control group

Results with reference substance (positive control):

The percent immobilisation observed at 24h were 0, 0, 15, 40 and 55 at the test concentrations of 0.09, 0.2, 0.44, 0.96 and 2.11 mg potassium dichromate/L, respectively. No immobility was observed in any of the replicates of the control group.
The percent immobilisation observed at 48h were 0, 15, 40, 60 and 100 at the test concentrations of 0.09, 0.2, 0.44, 0.96 and 2.11 mg potassium dichromate/L, respectively. No immobility was observed in any of the replicates of the control group.
At 24 h, in concentration 6 (2.11 mg/L) and concentration 5 (0.96 mg/L) lethargy, floating at surface of water and at bottom of test vessel were observed. In concentration 3 (0.20 mg/L) floating at bottom of test vessel was observed. No behavioural symptoms were observed in concentration 4 (0.44 mg/L). No immobility and behavioural symptoms were observed in concentration 2 (0.09 mg/L) and control groups.
At 48 h, complete immobilisation was observed in all replicates of concentration 6 (2.11 mg/L). In concentration 5 (0.96 mg/L) and concentration 3 (0.20 mg/L) lethargy and floating at surface of water were observed. In concentration 4 (0.44 mg/L) lethargy and floating at bottom of test vessel were observed. No immobility and behavioural symptoms were observed in concentration 2 (0.09 mg/L) and control groups.
The highest tested concentration of potassium dichromate causing no immobilisation and the No Observed Effect Concentration (NOEC) was 0.09 mg/L and the lowest tested concentration causing 100% immobilisation within the 48 h test period was 2.11 mg/L.
The Lowest Observed Effect Concentration (LOEC) was 0.20 mg/L over the 48 h exposure period of potassium dichromate.
The 24 and 48 h EC50 of potassium dichromate were determined 1.63 and 0.67 mg/L, respectively.

Validity criteria fulfilled:

yes

Conclusions:

Acute immobilisation study with D. magna (48 h) exposed to DABQUEL ZnP:
EC50 (48h): 24.9 mg ZnP/L
NOEC: 9.9 mg ZnP/L
LOEC: 14.8 mg ZnP/L

Executive summary:

A GLP-compliant key study on DABQUEL ZnP according to the OECD Guideline 202 (Acute Immobilisation of D. magna (48 h)) was performed. It had the following results:

EC50 (48h): 24.9 mg ZnP/L

NOEC: 9.9 mg ZnP/L

LOEC: 14.8 mg ZnP/L

Description of key information

Key study

A key study according to the OECD guideline 202 was performed to assess the toxic effects of the registered substance on Daphnia magna under static conditions.

Based on the results of the preliminary range finding study, the concentrations selected for the main study were 9.9, 14.8, 22.2, 33.3 and 50.0 mg/L. In the main study, a 48 h static toxicity test procedure was followed, comprising six groups. Each group consisted of four replicates with 5 daphnids per replicate.

The stability of the test item in test media was performed during method validation. The test item in test media was stable up to 48 h (>80% of nominal concentration). Test media was analysed for the active ingredient concentration and stability to monitor the concentration and stability of test solution at 0 and 48 h during main study. The active ingredient concentration of the registered substance in test media was within acceptable limit (>80% of nominal concentration).

The highest tested concentration of the registered substance causing no immobilisation and the No Observed Effect Concentration (NOEC) was 9.9 mg/L and the lowest tested concentration causing 100% immobilisation within the 48 h test period was 50.0 mg/L. The Lowest Observed Effect Concentration (LOEC) was 14.8 mg/L over the 48 h exposure period.

The EC50 (48 h) was determined to be 24.9 mg/L. As the test item has a zinc content of 14.2 %, the EC50 (48 h) for zinc is 3.536 mg/L.

Key value for chemical safety assessment

Fresh water invertebrates

Fresh water invertebrates

Effect concentration:

24.9 mg/L

Additional information

Impact of environmental conditions on zinc toxicity

In the key study an EC50 (48 h) value of 24.9 mg ZnGHA/L was obtained for Daphnia magna (Kamle, 2017). When comparing to EC50 (48 h)-values for D. magna found in literature converted to the target substance ZnGHA, the value obtained in the key study exceeds the other values (table 1). There are several studies underlining the fact, that aquatic zinc toxicity significantly depends on environmental factors like pH-value (Schubauer-Berigan et al. 1993, Hyne et al. 2005), water hardness (Hyne et al. 2005,Barata et al. 1998) and dissolved organic carbon (DOC) content (De Schamphelaere et al. 2005).

pH-value

Decreasing pH was shown to decrease the zinc toxicity toD. magna(De Schamphelaere et al. 2005) andCeriodaphnia cf dubia(Hyne et al. 2005, Schubauer-Berigan et al. 1993), significantly.

Dissolved organic Carbon (DOC)

Zinc toxicity toCeriodaphnia cf dubiawas not affected significantly by increasing DOC concentration (Hyne et al., 2005). De Schamphelaere et al. (2005), in contrast, concluded that zinc toxicity is reduced by DOC, due to its complexing activity. However, there is a great variation between DOC referring their zinc-binding characteristics (De Schamphelaere et al., 2005).

Water hardness

There is a significant impact of water hardness on zinc toxicity, due to inorganic complexation. Ceriodaphnia cf dubiaexposed to zinc in U.S. EPA synthetic soft water (hardness 44 mg CaCO3/L) at a pH of 7.5, gave a 48-h EC50 value of 155 µg/L. When water hardness was increased (374 mg CaCO3/L) at the same pH of 7.5, zinc toxicity toC. cf dubiawas decreased significantly by two- to three-fold with a 48-h EC50 value of 390 µg/L (Hyne et al. 2005). Comparable results were found forD. magna(Barata et al. 1998, De Schamphelaere et al., 2005).

Genetic factors

The intra-species variability between differentD. magnaclones regarding sensitivity to zinc was studied. The different clones were exposed to single-metal solutions of varying concentration at two or three levels of water hardness (soft, moderate–hard and hard) for periods ranging from 12–96 h (12 h increments). There was a 2-fold difference in the EC50 values between the least sensitive and the most sensitive clone.

Conclusion

As a conclusion, several factors have been shown to influencing the zinc toxicity in field which are not accounted for in standardized toxicity tests.

  

Table 1: Effect concentration (EC)-values from studies performed with elemental zinc (Zn²⁺) converted to ZnGHA under consideration of the molecular weight and the purity

Species	Duration of exposure	Dose descriptor	Basis for effect	elemental Zn in source substance [mg/L]	ZnGHA (75%) [mg/L]	Impact	Reference
Daphnia magna	48 h	EC50	Immobilisation	3.536	24.9		key study Kamle, 2017
D. magna	48 h	NOEC	Immobilisation	1.406	9.9
D. magna	48 h	LOEC	Immobilisation	2.102	14.8
D. magna	48 h	EC50	Immobilisation	0.259	1.63	soft water 125 +- 6.2 mg/L CaCO3 clone C	Barata et al. 1998
D. magna	48 h	EC50	Immobilisation	0.131	0.83	soft water clone A
D. magna	48 h	EC50	Immobilisation	1.060	6.69	moderate-hard water (203 +- 8.2 mg/L CaCO3) clone C
D. magna	48 h	EC50	Immobilisation	0.457	2.88	moderate-hard water clone A
D. magna	48 h	EC50	Immobilisation	0.962	6.07	hard water (357 +- 12.5 mg/L CaCO3) clone C
D. magna	48 h	EC50	Immobilisation	0.601	3.79	hard water clone A
D. magna	48 h	EC50	Immobilisation	1.833	11.57	laboratory clone	Muyssen et al. 2005
D. magna	48 h	EC50	Immobilisation	2.650	16.73	natural clone acclimized to natural water with pH8.2 and 7.2 mg DOC/L
D. magna	48 h	EC50	Immobilisation	2.909	18.36	natural clone acclimized to natural water with 7.3 mg Zn/L, pH 8.3 and 8.2 mg DOC/L
D. magna	48 h	EC50	Immobilisation	3.29	20.77	pH 8, DOC 7.49 mg/L, Ca 52.7	De Schamphelaere et al. 2005
D. magna	48 h	EC50	Immobilisation	0.354	2.23	pH 7.3, DOC 2.53 mg/L, Ca 5 mg/L
Tetrahymena pyriformis	1 h	EC50	activity of nonspecific esterase	0.2	1.26		Bogaerts et al. 1998
Ceriodaphnia sp.	48 h	EC50	Immobilisation	0.382	2.41	pH 5.5	Hyne et al. 2005
Ceriodaphnia sp.	48 h	EC50	Immobilisation	0.413	2.61	pH 6.5
Ceriodaphnia sp.	48 h	EC50	Immobilisation	0.2	1.26	pH7.5
Ceriodaphnia sp.	48 h	EC50	Immobilisation	0.155	0.98	hardness of 44 mg CaCO3/L at pH7.5
Ceriodaphnia sp.	48 h	EC50	Immobilisation	0.39	2.46	hardness of 374 mg CaCO3/L at pH7.5
D. magna		NOEC/EC10	reproduction	0.1517	0.96		ARCHE 2011
Rhithrogena hageni	96 h	LC50	mortality	50.5	318.75		Brinkman and Johnston 2008
C. dubia	48 h	LC50	mortality	>0.53	>3.35	pH 6-6.5	Schubauer-Berigan et al. 1993
C. dubia	48 h	LC50	mortality	0.36	2.27	pH 7-7.5
C. dubia	48 h	LC50	mortality	0.95	0.6	pH 8-8.5
C. dubia	48 h	EC50	mortality	0.67	4.23	acclimation to 3 µg Zn/L for 10 generations	Muyssen and Janssen 2002
C. dubia	48 h	EC50	mortality	0.8	5.05	acclimation to 13 µg Zn/L for 10 generations
C. dubia	48 h	EC50	mortality	0.507	3.2	acclimation to 50 µg Zn/L for 10 generations
C. dubia	48 h	EC50	mortality	0.507	3.2	acclimation to 100 µg Zn/L for 10 generations