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Toxicity to aquatic algae and cyanobacteria

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Endpoint:
toxicity to aquatic algae and cyanobacteria
Type of information:
read-across from supporting substance (structural analogue or surrogate)
Adequacy of study:
weight of evidence
Reason / purpose:
read-across source
Reason / purpose:
assessment report
Duration:
72 h
Dose descriptor:
EC50
Effect conc.:
300 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
biomass
Key result
Duration:
72 h
Dose descriptor:
EC50
Effect conc.:
315 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
growth rate
Details on results:
Test concentrations of 50 and 100 mg/L caused moderate inhibition of algae growth after 72 h. The test concentrations 1250, 2500, 5000 and 10000 mg/L resulted in total inhibition after 72 h.
Results with reference substance (positive control):
no reference substance (positive control) was tested.
Reported statistics and error estimates:
no data available
Validity criteria fulfilled:
yes
Conclusions:
The test item is not acute toxic to algae.
Executive summary:

The substance was tested in a study following OECD Guideline 201 and GLP. It is not acute toxic to algae.

EbC50(72h)= 300 mg/l;

ErC50( 72h) = 315 mg/l

The source substance contains the major organic moieties (hydroxysulfi(o)natoacetates) that are identical to the target substance. Therefore, this study shows that no toxicity to algae can be attributed to the hydroxysulfi(o)natoacetate moieties of the target substance TP 1646.

Endpoint:
toxicity to aquatic algae and cyanobacteria
Type of information:
read-across from supporting substance (structural analogue or surrogate)
Adequacy of study:
weight of evidence
Reason / purpose:
read-across source
Reason / purpose:
assessment report
Key result
Duration:
72 h
Dose descriptor:
IC50
Effect conc.:
0.55 mg/L
Nominal / measured:
meas. (initial)
Conc. based on:
element
Basis for effect:
growth rate
Duration:
72 h
Dose descriptor:
IC10
Effect conc.:
0.14 mg/L
Nominal / measured:
meas. (initial)
Conc. based on:
element
Basis for effect:
growth rate
Duration:
72 h
Dose descriptor:
LOEC
Effect conc.:
0.22 mg/L
Nominal / measured:
meas. (initial)
Conc. based on:
element
Basis for effect:
growth rate
Key result
Duration:
72 h
Dose descriptor:
NOEC
Effect conc.:
0.1 mg/L
Nominal / measured:
meas. (initial)
Conc. based on:
element
Basis for effect:
growth rate

The target substance contains 10 - 20 % Zn ions. Therefore, the hazard value for Zn ion is converted to the target substance considering a Zn content of 20 % as worst-case value.

IC50 (Zn ion) = 0.11 mg/L

IC 50 (TP 1646) = 0.11/0.2 = 0.55 mg/L

IC10 (Zn ion) = 0.028 mg/L

IC 10 (TP 1646) = 0.028/0.2 = 0.14 mg/L

LOEC (Zn ion) = 0.044 mg/L

LOEC (TP 1646) = 0.044/0.2 = 0.22 mg/L

NOEC (Zn ion) = 0.02 mg/L

NOEC (TP 1646) = 0.02/0.2 = 0.1 mg/L

Conclusions:
The Chlorella sp. culture acclimated to copper had no increased zinc tolerance compared with that of the nonacclimated algae, nor were there any changes in control growth rates. The IC50 of the non-acclimated culture was 110 µg Zn/L, whereas the culture acclimated to 2 µg Cu/L for 82 days showed an IC50 value of 98 µg Zn/L. The LOEC and NOEC for the non acclimated algae was 44 and 20 µg Zn/L, respectively. This result is also relevant for the target substance TP 1646, which contains 10 - 20 % zinc ions.
Executive summary:

Chlorella sp.was acclimated in medium containing 2 µg Cu/L for 100 days. Changes in algal growth rates and copper and zinc tolerance were monitored using standard growth inhibition toxicity tests in minimal medium over 72 h. The acclimated Chlorella sp. culture had no increased zinc tolerance compared with that of the nonacclimated algae, nor were there any changes in control growth rates. The IC50 of the non-acclimated culture was 110 µg Zn/L, whereas the culture acclimated to 2 µg Cu/L for 82 days showed an IC50 value of 98 µg Zn/L. The LOEC and NOEC for the non acclimated algae was 44 and 20 µg Zn/L, respectively. This result is also relevant for the target substance TP 1646, which contains 10 - 20 % zinc ions. Converted to the target substance under consideration of the zinc content of 20 % at the highest, the IC50 value is 0.55 mg/L.

Endpoint:
toxicity to aquatic algae and cyanobacteria
Type of information:
read-across from supporting substance (structural analogue or surrogate)
Adequacy of study:
weight of evidence
Reason / purpose:
read-across source
Reason / purpose:
assessment report
Duration:
72 h
Dose descriptor:
EC50
Remarks:
pH 5.7, DOC 6.28 mg/L, Ca 3.45 mg/L
Effect conc.:
10.25 mg/L
Nominal / measured:
meas. (initial)
Conc. based on:
element (dissolved fraction)
Basis for effect:
growth rate
Duration:
72 h
Dose descriptor:
EC50
Remarks:
pH 8.01, DOC 5.89 mg/L, Ca 65.4 mg/L
Effect conc.:
0.53 mg/L
Nominal / measured:
meas. (initial)
Conc. based on:
element (dissolved fraction)
Basis for effect:
growth rate
Duration:
72 h
Dose descriptor:
EC50
Remarks:
pH 7.42, DOC 22.3 mg/L, Ca 43.4 mg/L
Effect conc.:
4.305 mg/L
Nominal / measured:
meas. (initial)
Conc. based on:
element (dissolved fraction)
Basis for effect:
growth rate

The target substance contains 10 - 20 % Zn ions. Therefore, the hazard value for Zn ion is converted to the target substance considering a Zn content of 20 % as worst-case value.

EC50 (Zn ion) = 0.106 mg/L

EC 50 (TP 1646) = 0.106/0.2 = 0.53 mg/L

EC50 (Zn ion) = 0.861 mg/L

EC 50 (TP 1646) = 0.861/0.2 = 4.305 mg/L

EC50 (Zn ion) = 2.05 mg/L

EC 50 (TP 1646) = 2.05/0.2 = 10.25 mg/L

Conclusions:
An increase in Ca, Mg, and Na concentraion and pH value had protective effects on the zinc toxicity. Among these factors, the pH had the most significant effect. Both inorganic and organic Zn complexation reduces Zn2+ activity and thus also reduce toxicity. Inorganic complexation (i. e. ZnCO3) is relatively straightforward, while dissolved organic matter (DOM) vary much in their zinc-binding characteristics. This result is also relevant for the target substance TP 1646, which contains 10 - 20 % zinc ions. The EC50 values converted to the target substance TP 1646 range between 0.53 and 10.25 mg/L depending on the pH and DOC content.
Executive summary:

Zinc toxicity to a green alga (Pseudokirchneriella subcapitata) was evaluated in a series of experiments with spiked natural surface waters. The eight selected freshwater samples had varying levels of bioavailability modifying parameters: pH (5.7–8.4), dissolved organic carbon (DOC, 2.48–22.9 mg/L), Ca (1.5–80 mg/L), Mg (0.79–18 mg/L), and Na (3.8–120 mg/L). In those waters, chronic zinc toxicity (expressed as 10% effective concentrations [EC10]) varied up to 20-fold for the alga (72-h EC10 from 27.3 to 563 mg Zn/L). An increase in Ca, Mg, and Na concentraion and pH value had protective effects on the zinc toxicity, whereas the pH had the most significant effect. Both inorganic and organic Zn complexation reduces Zn2+ activity and thus also reduce toxicity. Inorganic complexation (i. e. ZnCO3) is relatively straightforward, while dissolved organic matter (DOM) vary much in their zinc-binding characteristics. This result is also relevant for the target substance TP 1646, which contains 10 - 20 % zinc ions. The EC50 values converted to the target substance TP 1646 range between 0.53 and 10.25 mg/L depending on the pH and DOC content.

Description of key information

Read-Across: WoE, FF6, D. subspicatus, OECD 201, GLP, 72 h, ErC50 = 315 mg/l

Read-Across: WoE, Zn, P. subcapitata, 72 h, ErC50 = 0.53 mg/L, 4.305 mg/L, 10.25 mg/L (values converted to the target substance considering the Zn content of 20 %)

Read-across: WoE, Zn, Chlorella sp., 72 h, ErC50 = 0.55 mg/L, ErC10 = 0.14 mg/L, LOEC = 0.22 mg/L, NOEC = 0.1 mg/L (values converted to the target substance considering the Zn content of 20 %)

Key value for chemical safety assessment

EC50 for freshwater algae:
0.53 mg/L
EC10 or NOEC for freshwater algae:
0.14 mg/L

Additional information

Read across - FF6:

The substance was tested in a study following OECD Guideline 201 and GLP. It is not acute toxic to algae.

EbC50(72h)= 300 mg/l;

ErC50( 72h) = 315 mg/l

The source substance contains the major organic moieties (hydroxysulfi(o)natoacetates) that are identical to the target substance. Therefore, this study shows that no toxicity to algae can be attributed to the hydroxysulfi(o)natoacetate moieties of the target substance TP 1646.

Read-across Zn-ion

The target substance contains 10 - 20 % Zn ions. Therefore, the hazard value for Zn ion is converted to the target substance considering a Zn content of 20 % as worst-case value.

De Schamphelaere, 2005

Zinc toxicity to a green alga (Pseudokirchneriella subcapitata) was evaluated in a series of experiments with spiked natural surface waters. The eight selected freshwater samples had varying levels of bioavailability modifying parameters: pH (5.7–8.4), dissolved organic carbon (DOC, 2.48–22.9 mg/L), Ca (1.5–80 mg/L), Mg (0.79–18 mg/L), and Na (3.8–120 mg/L). In those waters, chronic zinc toxicity (expressed as 10% effective concentrations [EC10]) varied up to 20-fold for the alga (72-h EC10 from 27.3 to 563 mg Zn/L). An increase in Ca, Mg, and Na concentraion and pH value had protective effects on the zinc toxicity, whereas the pH had the most significant effect. Both inorganic and organic Zn complexation reduces Zn2+ activity and thus also reduce toxicity. Inorganic complexation (i. e. ZnCO3) is relatively straightforward, while dissolved organic matter (DOM) vary much in their zinc-binding characteristics. This result is also relevant for the target substance TP 1646, which contains 10 - 20 % zinc ions. The EC50 values converted to the target substance TP 1646 range between 0.56 and 10.25 mg/L depending on the pH and DOC content.

Johnson 2007

Chlorella sp.was acclimated in medium containing 2 µg Cu/L for 100 days. Changes in algal growth rates and copper and zinc tolerance were monitored using standard growth inhibition toxicity tests in minimal medium over 72 h. The acclimated Chlorella sp. culture had no increased zinc tolerance compared with that of the nonacclimated algae, nor were there any changes in control growth rates. The IC50 of the non-acclimated culture was 110 µg Zn/L, whereas the culture acclimated to 2 µg Cu/L for 82 days showed an IC50 value of 98 µg Zn/L. The LOEC and NOEC for the non acclimated algae was 44 and 20 µg Zn/L, respectively. This result is also relevant for the target substance TP 1646, which contains 10 - 20 % zinc ions. Converted to the target substance under consideration of the zinc content of 20 % at the highest, the IC50 value is 0.55 mg/L.