Nickel(2+) diammonium 2,2',2'',2'''-(ethane-1,2-dinitrilo)tetraacetate

Toxicity to aquatic algae and cyanobacteria

Link to relevant study record(s)

Reference

Reference 1

Endpoint:

toxicity to aquatic algae and cyanobacteria

Type of information:

experimental study

Adequacy of study:

key study

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

study well documented, meets generally accepted scientific principles, acceptable for assessment

Qualifier:

equivalent or similar to guideline

Guideline:

OECD Guideline 201 (Alga, Growth Inhibition Test)

Version / remarks:

Dissolved nickel concentrations were measured at the start and end of testing. Acceptable statistics were used to determine 72 h NOEC, LOEC, EC10 and EC50 concentrations. A relevant endpoint (growth) was tested.

Principles of method if other than guideline:

An algal growth inhibition test was conducted using Pseudokirchneriella subcapitata in accordance with OECD Guideline 201. Short term (72 h) nickel toxicity tests were performed in synthetic test media containing a range of Ca and Mg concentrations and pH units. Various concentrations of nickel (as NiCl2) were added to these solutions and algal growth, as determined by cell densities, was monitored. Authors calculated a 72-h NOEC, LOEC, EC10, and EC50 for solutions with a range of Ca/Mg/pH characteristics.
The toxicity test was also undertaken using field collected water (physiochemical parameters of field-collected water were determined prior to nickel additions); however, the test conditions and results of those tests are not described in this record because field-collected media may contain other substances that could impact nickel toxicity.

GLP compliance:

not specified

Analytical monitoring:

yes

Details on sampling:

Intervals of water quality measurement: Ca, Mg, and Ni were measured at the start and end of growth inhibition tests.

Vehicle:

no

Test organisms (species):

Raphidocelis subcapitata (previous names: Pseudokirchneriella subcapitata, Selenastrum capricornutum)

Details on test organisms:

Test organisms (CCAP 278/4) were obtained from the Culture Collection of Algae and Protozoa (CCAP, at the Scottish Association for Marine Science, Argyll, Scotland, United Kingdom).
Age of inoculum (at test initiation): 5 d.

Test type:

static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

72 h

Hardness:

various, see result section

Test temperature:

25 °C

pH:

7.5

Nominal and measured concentrations:

For each inhibition growth test, a nickel concentration series was prepared and consisted of five or six consecutive nominal nickel concentrations out of the following: 10, 18, 32, 56, 100, 180, 320, 560, 1000, 3200, and 5600 µg/L.
Average (from tests at start and end of growth inhibition tests) measured nickel concentrations were used in data analysis to determine LOEC, NOEC, EC10, and EC50 concentrations; however, the average measured exposure concentrations were not reported in the publication.

Details on test conditions:

photo period: 24 h light
Algea growth was determined by measuring the cell densities at 48 h and 72 h.

Reference substance (positive control):

no

Key result

Duration:

72 h

Dose descriptor:

NOEC

Effect conc.:

>= 18 - <= 327 µg/L

Nominal / measured:

meas. (arithm. mean)

Conc. based on:

element (dissolved fraction)

Basis for effect:

growth rate

Remarks on result:

other: range represents the values calculated for 30 synthetic test solutions

Key result

Duration:

72 h

Dose descriptor:

LOEC

Effect conc.:

>= 31.5 - <= 953 µg/L

Nominal / measured:

meas. (arithm. mean)

Conc. based on:

element (dissolved fraction)

Basis for effect:

growth rate

Remarks on result:

other: range represents the values calculated for 30 synthetic test solutions

Key result

Duration:

72 h

Dose descriptor:

EC10

Effect conc.:

>= 25.3 - <= 365 µg/L

Nominal / measured:

meas. (arithm. mean)

Conc. based on:

element (dissolved fraction)

Basis for effect:

growth rate

Remarks on result:

other: range represents the values calculated for 30 synthetic test solutions

Key result

Duration:

72 h

Dose descriptor:

EC50

Effect conc.:

>= 81.5 - <= 1 120 µg/L

Nominal / measured:

meas. (arithm. mean)

Conc. based on:

element (dissolved fraction)

Basis for effect:

growth rate

Remarks on result:

other: range represents the values calculated for 30 synthetic test solutions

Key result

Duration:

72 h

Dose descriptor:

NOEC

Effect conc.:

>= 104 - <= 187 µg/L

Nominal / measured:

meas. (arithm. mean)

Conc. based on:

element (dissolved fraction)

Basis for effect:

growth rate

Remarks on result:

other: most relevant range for standard conditions (neutral pH, standard hardness)

Key result

Duration:

72 h

Dose descriptor:

LOEC

Effect conc.:

>= 186 - <= 320 µg/L

Nominal / measured:

meas. (arithm. mean)

Conc. based on:

element (dissolved fraction)

Basis for effect:

growth rate

Remarks on result:

other: most relevant range for standard conditions (neutral pH, standard hardness)

Key result

Duration:

72 h

Dose descriptor:

EC10

Effect conc.:

>= 180 - <= 292 µg/L

Nominal / measured:

meas. (arithm. mean)

Conc. based on:

element (dissolved fraction)

Basis for effect:

growth rate

Remarks on result:

other: most relevant range for standard conditions (neutral pH, standard hardness)

Key result

Duration:

72 h

Dose descriptor:

EC50

Effect conc.:

>= 601 - <= 914 µg/L

Nominal / measured:

meas. (arithm. mean)

Conc. based on:

element (dissolved fraction)

Basis for effect:

growth rate

Remarks on result:

other: most relevant range for standard conditions (neutral pH, standard hardness)

Table 1: Growth rate-based effect data (µg Nidiss/L) for all test solutions: 72-h NOEC, LOEC, EC10, and EC50. For EC10s and EC50s, 95% confidence intervals are given between brackets.

Test solution	72-h NOEC	72-h LOEC	72-h EC10	72-h EC50
Ca – 0.12 mM	18.0	32.3	30.3 (23.6-38.9)	93.7 (83.1-106)
Ca – 0.5 mM	21.2	36.7	36.6 (26.6-50.4)	108 (94.6-123)
Ca – 1.0 mM	34.5	48.4	37.3 (29.7-47.0)	114 (104-125)
Ca – 2.0 mM	54.0	102	51.9 (37.7-71.5)	136 (119-153)
Ca – 3.0 mM	31.9	49.3	31.5 (22.7-43.8)	122 (106-140)
Ca – 4.0 mM	26.2	51.0	42.1 (34.1-52.5)	144 (132-158)
Ca – 5.0 mM	48.6	97.2	40.5 (28.2-58.0)	141 (120-164)
Mg – 0.12 mM	-a	31.5	25.3 (17.6-35.9)	124 (107-144)
Mg – 0.5 mM	47.3	101	75.2 (55.7-101)	255 (226-284)
Mg – 1.0 mM	83.0	155	108 (81.5-144)	321 (284-361)
Mg – 1.5 mM	-a	89.4	124 (95.6-159)	399 (358-446)
Mg – 2.0 mM	88.9	163	162 (125-211)	596 (534-665)
Mg – 2.5 mM	154	280	252 (189-340)	742 (659-846)
Mg – 3.0 mM	285	953	213 (96.5-464)	812 (578-1140)
Mg – 4.0 mM	-a	278	284 (209-392)	821 (713-944)
Mg – 5.0 mM	292	537	365 (276-483)	1120 (992-1270)
pH – 6.0	-a	52.3	47.5 (42.1-53.0)	125 (119-133)
pH – 6.4	47.9	100	51.9 (43.8-61.6)	145 (136-156)
pH – 7.2	29.4	45.5	37.0 (30.9-44.3)	91.8 (84.8-98.5)
pH – 7.6	33.4	54.1	44.3 (39.7-48.9)	83.1 (79.8-87.4)
pH – 8.0	-a	16.6	35.9 (24.5-52.5)	81.5 (69.4-95.6)
pH – 6.0 / Mg 0.12 mM	68.4	104	57.6 (45.6-72.8)	172 (155-190)
pH – 6.0 / Mg 1.5 mM	327	570	312 (221-440)	880 (776-999)
pH – 6.0 / Mg 3.0 mM	181	326	145 (76.8-275)	883 (705-1110)
pH – 7.0 / Mg 0.12 mM	-a	55.7	26.5 (17.9-40.6)	108 (90.1-131)
pH – 7.0 / Mg 1.5 mM	104	186	180 (13.6-221)	601 (552-654)
pH – 7.0 / Mg 3.0 mM	187	320	292 (214-398)	914 (805-1040)
pH – 7.8 / Mg 0.12 mM	26.9	42.5	31.5 (23.9-41.4)	98.3 (87.3-111)
pH – 7.8 / Mg 1.5 mM	-a	38.1	44.3 (21.7-90.4)	345 (268-444)
pH – 7.8 / Mg 3.0 mM	65.0	103	91.2 (64.3-129)	395 (346-452)

a) A statistically significant effect was observed at the lowest exposure concentration tested.

Increasing the Mg concentration from 0.12 to 5.0 mM (nominal concentrations) resulted in a 9.0-fold (124 to 1120µg/L)increase of 72-h EC50

None of the 72-h EC50 obtained in the Ca test series were significantly different from that obtained for the test conducted at 0.12 mM Ca.

Overall, the toxicity of Ni+2 was observed to increase with increasing pH. When pH decreased from 7.92 to 6.45 (measured pH levels), the 72-h EC50 increased from 81.5 to 145µg/L.A further decrease of pH down to 6.01 did not result in a further increase of the 72-h EC50.

At all pH levels tested, Mg was observed to protect against nickel toxicity The results of the bivariate test design in which nickel toxicity was investigated at three different pH levels (6.0, 7.0 and 7.8, nominal values) and three different Mg concentrations (0.12, 1.5 and 3.0 mM Mg, nominal concentrations) found that, at pH 6.0, 7.0 and 7.8, an increase of the Mg concentration from 0.12 to 3.0 mM resulted in a 5.1, 8.5, and 4.0- fold increase of the 72-h EC50, respectively.

Validity criteria fulfilled:

not specified

Conclusions:

Based on the study results, the following ranges can be stated for the toxicity of Ni(2+) to algea:
NOEC, 72h: >= 18 <= 327 µg/L
LOEC, 72h: >= 31.5 <= 953 µg/L
EC10, 72h: >= 25.3 <= 365 µg/L
EC50, 72h: >= 81.5 <= 1120 µg/L
Due to the wide range of values the values given for standard cation concentrations in neutral water are considered to be most reliable:
NOEC, 72h: >= 104 <= 187 µg/L
LOEC, 72h: >= 186 <= 320 µg/L
EC10, 72h: >= 180 <= 292 µg/L
EC50, 72h: >= 601 <= 914 µg/L

Reference 2

Endpoint:

toxicity to aquatic algae and cyanobacteria

Type of information:

read-across from supporting substance (structural analogue or surrogate)

Adequacy of study:

key study

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

study well documented, meets generally accepted scientific principles, acceptable for assessment

Justification for type of information:

Edetic acid is known to be non-ecotoxic towards algea as proved by a study. Ammonium salts are widely used as fertilizers and are widely available in nature and thus known to be non-ecotoxic. Thus, the toxicity of nickel diammonium ethylenediaminetetraacetate towards algea is caused by the nickel moiety only. As a worst-case approach it is assumed that the metal is fully released from the complex within short time. As proved by the evaluation of biodegradation of the substance the metal is released over a longer period. Because metal ions bound in complexes are known to be less ecotoxic than the free ions, it can be concluded that the ecotoxicity of nickel diammonium ethylenediaminetetraacetate might be overestimated but not underestimated by this approach.

Reason / purpose for cross-reference:

read-across source

Qualifier:

according to guideline

Guideline:

OECD Guideline 201 (Alga, Growth Inhibition Test)

Version / remarks:

Dissolved nickel concentrations were measured at the start and end of testing. Acceptable statistics were used to determine 72 h NOEC, LOEC, EC10 and EC50 concentrations. A relevant endpoint (growth) was tested.

Principles of method if other than guideline:

An algal growth inhibition test was conducted using Pseudokirchneriella subcapitata in accordance with OECD Guideline 201. Short term (72 h) nickel toxicity tests were performed in synthetic test media containing a range of Ca and Mg concentrations and pH units. Various concentrations of nickel (as NiCl2) were added to these solutions and algal growth, as determined by cell densities, was monitored. Authors calculated a 72-h NOEC, LOEC, EC10, and EC50 for solutions with a range of Ca/Mg/pH characteristics.
The toxicity test was also undertaken using field collected water (physiochemical parameters of field-collected water were determined prior to nickel additions); however, the test conditions and results of those tests are not described in this record because field-collected media may contain other substances that could impact nickel toxicity.

GLP compliance:

not specified

Analytical monitoring:

yes

Details on sampling:

Intervals of water quality measurement: Ca, Mg, and Ni were measured at the start and end of growth inhibition tests.

Vehicle:

no

Test organisms (species):

Raphidocelis subcapitata (previous names: Pseudokirchneriella subcapitata, Selenastrum capricornutum)

Details on test organisms:

Test organisms (CCAP 278/4) were obtained from the Culture Collection of Algae and Protozoa (CCAP, at the Scottish Association for Marine Science, Argyll, Scotland, United Kingdom).
Age of inoculum (at test initiation): 5 d.

Test type:

static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

72 h

Hardness:

various, see result section

Test temperature:

25 °C

pH:

7.5

Nominal and measured concentrations:

For each inhibition growth test, a nickel concentration series was prepared and consisted of five or six consecutive nominal nickel concentrations out of the following: 10, 18, 32, 56, 100, 180, 320, 560, 1000, 3200, and 5600 µg/L.
Average (from tests at start and end of growth inhibition tests) measured nickel concentrations were used in data analysis to determine LOEC, NOEC, EC10, and EC50 concentrations; however, the average measured exposure concentrations were not reported in the publication.

Details on test conditions:

photo period: 24 h light
Algea growth was determined by measuring the cell densities at 48 h and 72 h.

Reference substance (positive control):

no

Key result

Duration:

72 h

Dose descriptor:

NOEC

Effect conc.:

>= 18 - <= 327 µg/L

Nominal / measured:

meas. (arithm. mean)

Conc. based on:

element (dissolved fraction)

Basis for effect:

growth rate

Remarks on result:

other: range represents the values calculated for 30 synthetic test solutions

Key result

Duration:

72 h

Dose descriptor:

LOEC

Effect conc.:

>= 31.5 - <= 953 µg/L

Nominal / measured:

meas. (arithm. mean)

Conc. based on:

element (dissolved fraction)

Basis for effect:

growth rate

Remarks on result:

other: range represents the values calculated for 30 synthetic test solutions

Key result

Duration:

72 h

Dose descriptor:

EC10

Effect conc.:

>= 25.3 - <= 365 µg/L

Nominal / measured:

meas. (arithm. mean)

Conc. based on:

element (dissolved fraction)

Basis for effect:

growth rate

Remarks on result:

other: range represents the values calculated for 30 synthetic test solutions

Key result

Duration:

72 h

Dose descriptor:

EC50

Effect conc.:

>= 81.5 - <= 1 120 µg/L

Nominal / measured:

meas. (arithm. mean)

Conc. based on:

element (dissolved fraction)

Basis for effect:

growth rate

Remarks on result:

other: range represents the values calculated for 30 synthetic test solutions

Key result

Duration:

72 h

Dose descriptor:

NOEC

Effect conc.:

>= 104 - <= 187 µg/L

Nominal / measured:

meas. (arithm. mean)

Conc. based on:

element (dissolved fraction)

Basis for effect:

growth rate

Remarks on result:

other: most relevant range for standard conditions (neutral pH, standard hardness)

Key result

Duration:

72 h

Dose descriptor:

LOEC

Effect conc.:

>= 186 - <= 320 µg/L

Nominal / measured:

meas. (arithm. mean)

Conc. based on:

element (dissolved fraction)

Basis for effect:

growth rate

Remarks on result:

other: most relevant range for standard conditions (neutral pH, standard hardness)

Key result

Duration:

72 h

Dose descriptor:

EC10

Effect conc.:

>= 180 - <= 292 µg/L

Nominal / measured:

meas. (arithm. mean)

Conc. based on:

element (dissolved fraction)

Basis for effect:

growth rate

Remarks on result:

other: most relevant range for standard conditions (neutral pH, standard hardness)

Key result

Duration:

72 h

Dose descriptor:

EC50

Effect conc.:

>= 601 - <= 914 µg/L

Nominal / measured:

meas. (arithm. mean)

Conc. based on:

element (dissolved fraction)

Basis for effect:

growth rate

Remarks on result:

other: most relevant range for standard conditions (neutral pH, standard hardness)

Table 1: Growth rate-based effect data (µg Nidiss/L) for all test solutions: 72-h NOEC, LOEC, EC10, and EC50. For EC10s and EC50s, 95% confidence intervals are given between brackets.

Test solution	72-h NOEC	72-h LOEC	72-h EC10	72-h EC50
Ca – 0.12 mM	18.0	32.3	30.3 (23.6-38.9)	93.7 (83.1-106)
Ca – 0.5 mM	21.2	36.7	36.6 (26.6-50.4)	108 (94.6-123)
Ca – 1.0 mM	34.5	48.4	37.3 (29.7-47.0)	114 (104-125)
Ca – 2.0 mM	54.0	102	51.9 (37.7-71.5)	136 (119-153)
Ca – 3.0 mM	31.9	49.3	31.5 (22.7-43.8)	122 (106-140)
Ca – 4.0 mM	26.2	51.0	42.1 (34.1-52.5)	144 (132-158)
Ca – 5.0 mM	48.6	97.2	40.5 (28.2-58.0)	141 (120-164)
Mg – 0.12 mM	-a	31.5	25.3 (17.6-35.9)	124 (107-144)
Mg – 0.5 mM	47.3	101	75.2 (55.7-101)	255 (226-284)
Mg – 1.0 mM	83.0	155	108 (81.5-144)	321 (284-361)
Mg – 1.5 mM	-a	89.4	124 (95.6-159)	399 (358-446)
Mg – 2.0 mM	88.9	163	162 (125-211)	596 (534-665)
Mg – 2.5 mM	154	280	252 (189-340)	742 (659-846)
Mg – 3.0 mM	285	953	213 (96.5-464)	812 (578-1140)
Mg – 4.0 mM	-a	278	284 (209-392)	821 (713-944)
Mg – 5.0 mM	292	537	365 (276-483)	1120 (992-1270)
pH – 6.0	-a	52.3	47.5 (42.1-53.0)	125 (119-133)
pH – 6.4	47.9	100	51.9 (43.8-61.6)	145 (136-156)
pH – 7.2	29.4	45.5	37.0 (30.9-44.3)	91.8 (84.8-98.5)
pH – 7.6	33.4	54.1	44.3 (39.7-48.9)	83.1 (79.8-87.4)
pH – 8.0	-a	16.6	35.9 (24.5-52.5)	81.5 (69.4-95.6)
pH – 6.0 / Mg 0.12 mM	68.4	104	57.6 (45.6-72.8)	172 (155-190)
pH – 6.0 / Mg 1.5 mM	327	570	312 (221-440)	880 (776-999)
pH – 6.0 / Mg 3.0 mM	181	326	145 (76.8-275)	883 (705-1110)
pH – 7.0 / Mg 0.12 mM	-a	55.7	26.5 (17.9-40.6)	108 (90.1-131)
pH – 7.0 / Mg 1.5 mM	104	186	180 (13.6-221)	601 (552-654)
pH – 7.0 / Mg 3.0 mM	187	320	292 (214-398)	914 (805-1040)
pH – 7.8 / Mg 0.12 mM	26.9	42.5	31.5 (23.9-41.4)	98.3 (87.3-111)
pH – 7.8 / Mg 1.5 mM	-a	38.1	44.3 (21.7-90.4)	345 (268-444)
pH – 7.8 / Mg 3.0 mM	65.0	103	91.2 (64.3-129)	395 (346-452)

a) A statistically significant effect was observed at the lowest exposure concentration tested.

Increasing the Mg concentration from 0.12 to 5.0 mM (nominal concentrations) resulted in a 9.0-fold (124 to 1120µg/L)increase of 72-h EC50

None of the 72-h EC50 obtained in the Ca test series were significantly different from that obtained for the test conducted at 0.12 mM Ca.

Overall, the toxicity of Ni+2 was observed to increase with increasing pH. When pH decreased from 7.92 to 6.45 (measured pH levels), the 72-h EC50 increased from 81.5 to 145µg/L.A further decrease of pH down to 6.01 did not result in a further increase of the 72-h EC50.

At all pH levels tested, Mg was observed to protect against nickel toxicity The results of the bivariate test design in which nickel toxicity was investigated at three different pH levels (6.0, 7.0 and 7.8, nominal values) and three different Mg concentrations (0.12, 1.5 and 3.0 mM Mg, nominal concentrations) found that, at pH 6.0, 7.0 and 7.8, an increase of the Mg concentration from 0.12 to 3.0 mM resulted in a 5.1, 8.5, and 4.0- fold increase of the 72-h EC50, respectively.

Validity criteria fulfilled:

not specified

Conclusions:

most relevant range for standard conditions (neutral pH, standard hardness)


Based on the study results, the following ranges can be stated for the toxicity of Ni(2+) to algea:
NOEC, 72h: >= 18 <= 327 µg/L
LOEC, 72h: >= 31.5 <= 953 µg/L
EC10, 72h: >= 25.3 <= 365 µg/L
EC50, 72h: >= 81.5 <= 1120 µg/L
Due to the wide range of values the values given for standard cation concentrations in neutral water are considered to be most reliable:
NOEC, 72h: >= 104 <= 187 µg/L
LOEC, 72h: >= 186 <= 320 µg/L
EC10, 72h: >= 180 <= 292 µg/L
EC50, 72h: >= 601 <= 914 µg/L

Those most reliable values are recalculated for EDTA-Ni(NH4)2 by molecular weight correction:
383.0 g/mol / 58.7 g/mol x NOEC/LOEC/ECx
NOEC, 72h: >= 0.679 <= 1.22 mg/L
LOEC, 72h: >= 1.21 <= 2.09 mg/L
EC10, 72h: >= 1.17 <= 1.91 mg/L
EC50, 72h: >= 3.92 <= 5.96 mg/L

Reference 3

Endpoint:

toxicity to aquatic algae and cyanobacteria

Type of information:

experimental study

Adequacy of study:

key study

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

study well documented, meets generally accepted scientific principles, acceptable for assessment

Qualifier:

according to guideline

Guideline:

OECD Guideline 201 (Alga, Growth Inhibition Test)

GLP compliance:

not specified

Remarks:

GLP compliance is not specified. Nevertheless, the study is well reported and thus considered as reliable.

Analytical monitoring:

yes

Details on sampling:

One hard
water region and one adjoining soft water region were
selected for sampling. These regions were !ocated approximately
200-300 km northwest of Stockholm (geographic area
60'04'49''-61'59'49"N and 15'46'17"-17'14'08"E).

Vehicle:

no

Test organisms (species):

Raphidocelis subcapitata (previous names: Pseudokirchneriella subcapitata, Selenastrum capricornutum)

Details on test organisms:

Several species were used for thsi study:
Chlamydomonas sp., Ankistrodesmus falcatus, Scenedesmus accuminatus, Chlorella sp., Desmodesmus spinosus, Pediastrum duplex, Pseudokirchneriella sp., Coelastrum microporum, Spermatozopsis exsultans

Test type:

static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

72 h

Hardness:

During isolation and culturing. water hardness of the growth medium was adjusted to either 6.25 mg CaCO3/L (soft water strains) or 43.4 mg CaCO3/L (hard water strains).
The water hardness of the 'soft', 'moderately hard' and 'hard' test medium was 6.25. 16.3 and 43.4 mg CaCO3/L, respectively.

Test temperature:

25 °C

pH:

7.1 - 7.3

Details on test conditions:

The flasks were placed on a shaking device under continuous light (120 μmol photons/m2/s).

Reference substance (positive control):

no

Key result

Duration:

72 h

Dose descriptor:

EC50

Effect conc.:

>= 40.7 - <= 1 430 µg/L

Nominal / measured:

meas. (arithm. mean)

Conc. based on:

element (dissolved fraction)

Basis for effect:

growth rate

Key result

Duration:

72 h

Dose descriptor:

EC10

Effect conc.:

>= 4.9 - <= 100 µg/L

Nominal / measured:

meas. (arithm. mean)

Conc. based on:

element (dissolved fraction)

Basis for effect:

growth rate

Key result

Duration:

72 h

Dose descriptor:

LOEC

Effect conc.:

>= 6.2 - <= 168 µg/L

Nominal / measured:

meas. (arithm. mean)

Conc. based on:

element (dissolved fraction)

Basis for effect:

growth rate

Key result

Duration:

72 h

Dose descriptor:

NOEC

Effect conc.:

>= 3.5 - <= 98.2 µg/L

Nominal / measured:

meas. (arithm. mean)

Conc. based on:

element (dissolved fraction)

Basis for effect:

growth rate

Key result

Duration:

72 h

Dose descriptor:

EC50

Remarks:

hard water

Effect conc.:

>= 97.2 - <= 559 µg/L

Nominal / measured:

meas. (arithm. mean)

Conc. based on:

element (dissolved fraction)

Basis for effect:

growth rate

Key result

Duration:

72 h

Dose descriptor:

EC50

Remarks:

moderate hard water

Effect conc.:

>= 40.7 - <= 1 430 µg/L

Nominal / measured:

meas. (arithm. mean)

Conc. based on:

element (dissolved fraction)

Basis for effect:

growth rate

Key result

Duration:

72 h

Dose descriptor:

EC50

Remarks:

soft water

Effect conc.:

>= 83.3 - <= 826 µg/L

Nominal / measured:

meas. (arithm. mean)

Conc. based on:

element (dissolved fraction)

Basis for effect:

growth rate

Key result

Duration:

72 h

Dose descriptor:

NOEC

Remarks:

hard water

Effect conc.:

>= 14 - < 140 µg/L

Nominal / measured:

meas. (arithm. mean)

Conc. based on:

element (dissolved fraction)

Basis for effect:

growth rate

Key result

Duration:

72 h

Dose descriptor:

NOEC

Remarks:

moderate hard water

Effect conc.:

>= 3.5 - < 97.7 µg/L

Nominal / measured:

meas. (arithm. mean)

Conc. based on:

element (dissolved fraction)

Basis for effect:

growth rate

Key result

Duration:

72 h

Dose descriptor:

NOEC

Remarks:

soft water

Effect conc.:

>= 8.3 - <= 98.2 µg/L

Nominal / measured:

meas. (arithm. mean)

Conc. based on:

element (dissolved fraction)

Basis for effect:

growth rate

Table: EC50, EC10 and NOEC values determined by growth inhibition test for different species and conditions in dissolved µg Ni/L

Site	Species	Water Type	72h NOErC	72h LOErC	72h ErC10	72h ErC50
H10	Desmodesmus spinosus	hard, test 1	43.3	91.1	98.0	517
H10	Desmodesmus spinosus	hard, test 2	96.2	168	67.7	333
H10	Pediastrum duplex	hard	39.5	77.2	16.4	97.2
H11	Pseudokirchneriella sp.	hard	13.8	25.9	12.9	140
H12	Coelastrum microporum	hard, test 1	< 140	140	54.3	243
H12	Coelastrum microporum	hard, test 2	< 40.2	40.2	100	559
H12	Spermatozopsis exsultans	hard	< 41.9	41.9	28.6	263
H10	Desmodesmus spinosus	moderately hard, test 1	43.7	92.1	86.8	236
H10	Desmodesmus spinosus	moderately hard, test 2	29.1	46.9	67.7	140
H10	Pediastrum duplex	moderately hard	23.5	38.3	32.2	40.7
H11	Pseudokirchneriella sp.	moderately hard	3.5	7.5	4.9	68.9
H12	Coelastrum microporum	moderately hard, test 1	< 84.0	84.0	38.6	139
H12	Coelastrum microporum	moderately hard, test 2	< 31.2	31.2	66.7	280
H12	Spermatozopsis exsultans	moderately hard	< 22.9	22.9	17.1	118
S14	Chlamydomonas sp.	soft	8.3	16.0	26.4	58.8
S14	Ankistrodesmus falcatus	soft	24.5	42.9	18.3	237
S18	Scenedesmus accuminatus	soft	< 6.2	6.2	7.0	83.3
S18	Chlorella sp.	soft	98.2	168	64.7	826
S21	Desmodesmus spinosus	soft	< 6.9	6.9	5.5	88.1
S14	Chlamydomonas sp.	moderately hard	27.5	42.2	45.0	147
S14	Ankistrodesmus falcatus	moderately hard	43.0	105	43.6	394
S18	Scenedesmus accuminatus	moderately hard	12.3	25.4	18.5	189
S18	Chlorella sp.	moderately hard	< 97.7	97.7	90.5	1430
S21	Desmodesmus spinosus	moderately hard	22.5	41.7	28.9	171

For two species, two tests were performed

In some cases, the NOErC was higher than the ErC10. This is due to partial overlap of the growth rate ranges at the lower exposure concentrations with the growth rate range in the control while average growth rates gradually decreased.

Validity criteria fulfilled:

not specified

Conclusions:

The toxicity of nickel towards algea varies widely between the species. The ErC50, 72h can be stated to be >= 40.7 and <= 1430 µg Ni/L. The NOErC can be stated to be >= 3.5 and <= 98.2 µg Ni/L. The average values are ErC50 = 283 µg Ni/L and NOErC = 41.7 µg Ni/L, respectively.

Executive summary:

Table: Summary of ErC50 and NOErC values for different water types, in µg Ni/L

	ErC50	NOErC
hard water	97 - 559	14 - 140
moderate hard water	41 - 1430	3.5 - 98
soft water	83 - 826	8 - 98
average	41.7	283

Reference 4

Endpoint:

toxicity to aquatic algae and cyanobacteria

Type of information:

read-across from supporting substance (structural analogue or surrogate)

Adequacy of study:

key study

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

study well documented, meets generally accepted scientific principles, acceptable for assessment

Justification for type of information:

Edetic acid is known to be non-ecotoxic towards algea as proved by a study. Ammonium salts are widely used as fertilizers and are widely available in nature and thus known to be non-ecotoxic. Thus, the toxicity of nickel diammonium ethylenediaminetetraacetate towards algea is caused by the nickel moiety only. As a worst-case approach it is assumed that the metal is fully released from the complex within short time. As proved by the evaluation of biodegradation of the substance the metal is released over a longer period. Because metal ions bound in complexes are known to be less ecotoxic than the free ions, it can be concluded that the ecotoxicity of nickel diammonium ethylenediaminetetraacetate might be overestimated but not underestimated by this approach.

Reason / purpose for cross-reference:

read-across source

Qualifier:

according to guideline

Guideline:

OECD Guideline 201 (Alga, Growth Inhibition Test)

GLP compliance:

not specified

Remarks:

GLP compliance is not specified. Nevertheless, the study is well reported and thus considered as reliable.

Analytical monitoring:

yes

Details on sampling:

One hard
water region and one adjoining soft water region were
selected for sampling. These regions were !ocated approximately
200-300 km northwest of Stockholm (geographic area
60'04'49''-61'59'49"N and 15'46'17"-17'14'08"E).

Vehicle:

no

Test organisms (species):

Raphidocelis subcapitata (previous names: Pseudokirchneriella subcapitata, Selenastrum capricornutum)

Details on test organisms:

Several species were used for thsi study:
Chlamydomonas sp., Ankistrodesmus falcatus, Scenedesmus accuminatus, Chlorella sp., Desmodesmus spinosus, Pediastrum duplex, Pseudokirchneriella sp., Coelastrum microporum, Spermatozopsis exsultans

Test type:

static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

72 h

Hardness:

During isolation and culturing. water hardness of the growth medium was adjusted to either 6.25 mg CaCO3/L (soft water strains) or 43.4 mg CaCO3/L (hard water strains).
The water hardness of the 'soft', 'moderately hard' and 'hard' test medium was 6.25. 16.3 and 43.4 mg CaCO3/L, respectively.

Test temperature:

25 °C

pH:

7.1 - 7.3

Details on test conditions:

The flasks were placed on a shaking device under continuous light (120 μmol photons/m2/s).

Reference substance (positive control):

no

Key result

Duration:

72 h

Dose descriptor:

EC50

Effect conc.:

>= 40.7 - <= 1 430 µg/L

Nominal / measured:

meas. (arithm. mean)

Conc. based on:

element (dissolved fraction)

Basis for effect:

growth rate

Key result

Duration:

72 h

Dose descriptor:

EC10

Effect conc.:

>= 4.9 - <= 100 µg/L

Nominal / measured:

meas. (arithm. mean)

Conc. based on:

element (dissolved fraction)

Basis for effect:

growth rate

Key result

Duration:

72 h

Dose descriptor:

LOEC

Effect conc.:

>= 6.2 - <= 168 µg/L

Nominal / measured:

meas. (arithm. mean)

Conc. based on:

element (dissolved fraction)

Basis for effect:

growth rate

Key result

Duration:

72 h

Dose descriptor:

NOEC

Effect conc.:

>= 3.5 - <= 98.2 µg/L

Nominal / measured:

meas. (arithm. mean)

Conc. based on:

element (dissolved fraction)

Basis for effect:

growth rate

Key result

Duration:

72 h

Dose descriptor:

EC50

Remarks:

hard water

Effect conc.:

>= 97.2 - <= 559 µg/L

Nominal / measured:

meas. (arithm. mean)

Conc. based on:

element (dissolved fraction)

Basis for effect:

growth rate

Key result

Duration:

72 h

Dose descriptor:

EC50

Remarks:

moderate hard water

Effect conc.:

>= 40.7 - <= 1 430 µg/L

Nominal / measured:

meas. (arithm. mean)

Conc. based on:

element (dissolved fraction)

Basis for effect:

growth rate

Key result

Duration:

72 h

Dose descriptor:

EC50

Remarks:

soft water

Effect conc.:

>= 83.3 - <= 826 µg/L

Nominal / measured:

meas. (arithm. mean)

Conc. based on:

element (dissolved fraction)

Basis for effect:

growth rate

Key result

Duration:

72 h

Dose descriptor:

NOEC

Remarks:

hard water

Effect conc.:

>= 14 - < 140 µg/L

Nominal / measured:

meas. (arithm. mean)

Conc. based on:

element (dissolved fraction)

Basis for effect:

growth rate

Key result

Duration:

72 h

Dose descriptor:

NOEC

Remarks:

moderate hard water

Effect conc.:

>= 3.5 - < 97.7 µg/L

Nominal / measured:

meas. (arithm. mean)

Conc. based on:

element (dissolved fraction)

Basis for effect:

growth rate

Key result

Duration:

72 h

Dose descriptor:

NOEC

Remarks:

soft water

Effect conc.:

>= 8.3 - <= 98.2 µg/L

Nominal / measured:

meas. (arithm. mean)

Conc. based on:

element (dissolved fraction)

Basis for effect:

growth rate

Table: EC50, EC10 and NOEC values determined by growth inhibition test for different species and conditions in dissolved µg Ni/L

Site	Species	Water Type	72h NOErC	72h LOErC	72h ErC10	72h ErC50
H10	Desmodesmus spinosus	hard, test 1	43.3	91.1	98.0	517
H10	Desmodesmus spinosus	hard, test 2	96.2	168	67.7	333
H10	Pediastrum duplex	hard	39.5	77.2	16.4	97.2
H11	Pseudokirchneriella sp.	hard	13.8	25.9	12.9	140
H12	Coelastrum microporum	hard, test 1	< 140	140	54.3	243
H12	Coelastrum microporum	hard, test 2	< 40.2	40.2	100	559
H12	Spermatozopsis exsultans	hard	< 41.9	41.9	28.6	263
H10	Desmodesmus spinosus	moderately hard, test 1	43.7	92.1	86.8	236
H10	Desmodesmus spinosus	moderately hard, test 2	29.1	46.9	67.7	140
H10	Pediastrum duplex	moderately hard	23.5	38.3	32.2	40.7
H11	Pseudokirchneriella sp.	moderately hard	3.5	7.5	4.9	68.9
H12	Coelastrum microporum	moderately hard, test 1	< 84.0	84.0	38.6	139
H12	Coelastrum microporum	moderately hard, test 2	< 31.2	31.2	66.7	280
H12	Spermatozopsis exsultans	moderately hard	< 22.9	22.9	17.1	118
S14	Chlamydomonas sp.	soft	8.3	16.0	26.4	58.8
S14	Ankistrodesmus falcatus	soft	24.5	42.9	18.3	237
S18	Scenedesmus accuminatus	soft	< 6.2	6.2	7.0	83.3
S18	Chlorella sp.	soft	98.2	168	64.7	826
S21	Desmodesmus spinosus	soft	< 6.9	6.9	5.5	88.1
S14	Chlamydomonas sp.	moderately hard	27.5	42.2	45.0	147
S14	Ankistrodesmus falcatus	moderately hard	43.0	105	43.6	394
S18	Scenedesmus accuminatus	moderately hard	12.3	25.4	18.5	189
S18	Chlorella sp.	moderately hard	< 97.7	97.7	90.5	1430
S21	Desmodesmus spinosus	moderately hard	22.5	41.7	28.9	171

For two species, two tests were performed

In some cases, the NOErC was higher than the ErC10. This is due to partial overlap of the growth rate ranges at the lower exposure concentrations with the growth rate range in the control while average growth rates gradually decreased.

Validity criteria fulfilled:

not specified

Conclusions:

The toxicity of nickel towards algea varies widely between the species. The ErC50, 72h can be stated to be >= 40.7 and <= 1430 µg Ni/L. The NOErC can be stated to be >= 3.5 and <= 98.2 µg Ni/L. The average values are ErC50 = 283 µg Ni/L and NOErC = 41.7 µg Ni/L, respectively.
Those average values are recalculated for EDTA-Ni(NH4)2 by molecular weight correction:
ErC50 = 383.0 g/mol / 58.7 g/mol x ErC50 and NOErC = 383.0 g/mol / 58.7 g/mol x NOErC, respectively:
ErC50 = 1.85 mg/L
NOErC = 272 µg/L

Executive summary:

Table: Summary of ErC50 and NOErC values for different water types, in µg Ni/L

	ErC50	NOErC
hard water	97 - 559	14 - 140
moderate hard water	41 - 1430	3.5 - 98
soft water	83 - 826	8 - 98
average	41.7	283

Reference 5

Endpoint:

toxicity to aquatic algae and cyanobacteria

Type of information:

experimental study

Adequacy of study:

key study

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

data from handbook or collection of data

Justification for type of information:

The report summarizes all available information on the toxicity and ecotoxicity of edetic acid itself and also in presence of metal ions. It was prepared by an official national authority of the European Union. Thus it is considered to be reliable as data source.

Qualifier:

no guideline required

Principles of method if other than guideline:

The report summarizes all available information on the toxicity and ecotoxicity of edetic acid itself and also in presence of metal ions. It was prepared by an official national authority of the European Union. Thus it is considered to be reliable as data source.

GLP compliance:

not specified

Key result

Duration:

72 h

Dose descriptor:

NOEC

Effect conc.:

310 mg/L

Conclusions:

The report states the following:
The apparent effects of complexing agents to algal growth are related to essential trace metal bioavailability. It was demonstrated that not the absolute EDTA concentration, but rather the ratio of the EDTA concentration to the metal cations is crucial to algae growth. With sufficient trace metal amounts, H4EDTA concentrations up to 310 mg/l caused no effects. Similar results are obtained when Fe(III)EDTA is used as test substance, due to its slow metal exchange kinetics overchelation of the nutrient metal ions is avoided. Therefore direct effects caused by the intrinsic toxicity of EDTA are not expected in surface waters, where in nearly every case a stoichiometric surplus of metal ions is present.

Thus the NOEC can be stated to be >= 310 mg/L.

Reference 6

Endpoint:

toxicity to aquatic algae and cyanobacteria

Type of information:

read-across from supporting substance (structural analogue or surrogate)

Adequacy of study:

key study

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

data from handbook or collection of data

Justification for type of information:

The report summarizes all available information on the toxicity and ecotoxicity of edetic acid itself and also in presence of metal ions. It was prepared by an official national authority of the European Union. Thus it is considered to be reliable as data source.

Reason / purpose for cross-reference:

read-across source

Qualifier:

no guideline required

Principles of method if other than guideline:

The report summarizes all available information on the toxicity and ecotoxicity of edetic acid itself and also in presence of metal ions. It was prepared by an official national authority of the European Union. Thus it is considered to be reliable as data source.

GLP compliance:

not specified

Key result

Duration:

72 h

Dose descriptor:

NOEC

Effect conc.:

310 mg/L

Conclusions:

The report states the following:
The apparent effects of complexing agents to algal growth are related to essential trace metal bioavailability. It was demonstrated that not the absolute EDTA concentration, but rather the ratio of the EDTA concentration to the metal cations is crucial to algae growth. With sufficient trace metal amounts, H4EDTA concentrations up to 310 mg/l caused no effects. Similar results are obtained when Fe(III)EDTA is used as test substance, due to its slow metal exchange kinetics overchelation of the nutrient metal ions is avoided. Therefore direct effects caused by the intrinsic toxicity of EDTA are not expected in surface waters, where in nearly every case a stoichiometric surplus of metal ions is present.

Thus the NOEC can be stated to be >= 310 mg/L.
It can be stated that the LC50 value for edetic acid is much higher than for nickel salts. Thus the aquatic toxicity of nickel diammonium ethylenediaminetetraacetate is determined by the nickel moiety of the substance.

Reference 7

Endpoint:

toxicity to aquatic algae and cyanobacteria

Type of information:

experimental study

Adequacy of study:

weight of evidence

Study period:

2001-03-19 to 2001-04-06

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

OECD Guideline 201 (Alga, Growth Inhibition Test)

Version / remarks:

1984

Deviations:

no

GLP compliance:

yes

Specific details on test material used for the study:

SOURCE OF TEST MATERIAL
- Lot/batch No.of test material: A0102232 (01)

STABILITY AND STORAGE CONDITIONS OF TEST MATERIAL
- Stability under test conditions: assumed to be stable at storage conditions
- Storage condition of test material: at room temperature in the dark

Analytical monitoring:

yes

Details on sampling:

Samples of about 3 mL were taken from 3 control vessels and from each test vessels containing test substance at 0 24, 48 and 72 hours. The samples were stored in the freezer (<=10 °C) until analyses.

Vehicle:

no

Details on test solutions:

PREPARATION AND APPLICATION OF TEST SOLUTION
A stock solution/suspension of the test substance was prepared as follows: an accurately measured amount of 0.6526 g of test substance was dissolved in deionized water. Exactiy 4.0 ml of a 118.5 g/L FeCI3x6H20 was added with a pipette to reach an equimolar concentration of EDTA and Fe(lll). After stirring the pH of the solution was adjusted to pH 5.2 using a 1 M NaOH Solution. The final concentration of 5.1237 g/L based on H4EDTA was reached by adding deionized water to a final volume of 100 mL. The stock Solution was stored in the refrigerator in the dark.
The test solutions were prepared by addition of the required amounts of stock Solution to the test vessels to obtain the following final nominal test concentrations: 60, 80 and 100 mg/L.

Test organisms (species):

Raphidocelis subcapitata (previous names: Pseudokirchneriella subcapitata, Selenastrum capricornutum)

Details on test organisms:

TEST ORGANISM
- Common name: P.subcapitata
- Strain: CCAP 278/4
- Source (laboratory, culture collection): Culture Collection of Algae and Protozoa, Institute of Freshwater Ecology, The Windermere Laboratory, Cumbria, Ambleside, United Kingdom.

Test type:

static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

72 h

Test temperature:

23 ± 2 °C

Salinity:

Not applicable

Nominal and measured concentrations:

Nominal concentrations of 60, 80 and 100 mg/L

Details on test conditions:

TEST SYSTEM
- Test vessel: Erlenmeyer test flasks
- Type (delete if not applicable): open / closed
- Material, size, headspace, fill volume: 100 mL, closed with cotton-wool stoppers

GROWTH MEDIUM
- Standard medium used: yes

OTHER TEST CONDITIONS
- Adjustment of pH: jes
- Light intensity and quality: continuous uniform illumination was provided in the spectral ränge of 400 to 700 nm by using 30 W fluorescent lamps


EFFECT PARAMETERS MEASURED:
- Determination of cell concentrations: photometrically with a UVA/IS Spectrophotometer

Reference substance (positive control):

no

Duration:

72 h

Dose descriptor:

EC50

Effect conc.:

> 100 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

growth rate

Duration:

72 h

Dose descriptor:

EC50

Effect conc.:

> 60 mg/L

Nominal / measured:

meas. (geom. mean)

Conc. based on:

test mat.

Basis for effect:

growth rate

Duration:

72 h

Dose descriptor:

NOEC

Effect conc.:

79.4 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

growth rate

Duration:

72 h

Dose descriptor:

NOEC

Effect conc.:

48.4 mg/L

Nominal / measured:

meas. (geom. mean)

Conc. based on:

test mat.

Basis for effect:

growth rate

Duration:

72 h

Dose descriptor:

LOEC

Effect conc.:

99.9 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

growth rate

Duration:

72 h

Dose descriptor:

LOEC

Effect conc.:

60.6 mg/L

Nominal / measured:

meas. (geom. mean)

Conc. based on:

test mat.

Basis for effect:

growth rate

Validity criteria fulfilled:

yes

Conclusions:

In conclusion the 72 hour EC50 value for Fe(III)EDTA with P.subcapitata was greater than 100 mg/L based on nominal concentrations and greater than 60 mg/L based on the mean measured concentrations. The NOEC was 79.4 mg/L based on nominal concentrations and 48.4 mg/L based on the mean measured concentrations.

Executive summary:

The toxicity of Fe(lll)EDTA to exponentially growing Pseudokirchneriella subcapitata was determined over an exposure period of 72 hours. A test was carried out at nominal concentrations of 60, 80 and 100 mg/L Fe (lll) EDTA (concentrations represented as H4EDTA).Due to photodegradation, the Fe(lll)EDTA concentration declines during the test. The chemical analyses carried out showed that the concentration of the test compound at the end of the test had decreased to about 50 % of the concentration at the beginning of the test. The mean concentrations during the 72 hours of testing for the nominal concentrations of 60, 80 and 100 mg/L as measured by chemical analyses were 38.1, 48.4 and 60.6 mg/L, respectively. The test was conducted in a mineral salt medium in a climatized illuminated orbital incubator. The maximum variation in pH in the test media was 1.4 pH unit. In conclusion the 72 hour EC50-value for Fe(III)EDTA with P.subcapitata was greater than 100 mg/L based on nominal concentrations and greater than 60 mg/L based on the mean measured concentrations. The NOEC was 79.4 mg/L based on nominal concentrations and 48.4 mg/L based on the mean measured concentrations.

Reference 8

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

Study period:

2001-03-19 to 2001-04-06

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Justification for type of information:

This study is provided to support the conclusion that edetic acid is non-ecotoxic towards aquatic algae.

Reason / purpose for cross-reference:

read-across source

Qualifier:

according to guideline

Guideline:

OECD Guideline 201 (Alga, Growth Inhibition Test)

Version / remarks:

1984

Deviations:

no

GLP compliance:

yes

Specific details on test material used for the study:

SOURCE OF TEST MATERIAL
- Lot/batch No.of test material: A0102232 (01)

STABILITY AND STORAGE CONDITIONS OF TEST MATERIAL
- Stability under test conditions: assumed to be stable at storage conditions
- Storage condition of test material: at room temperature in the dark

Analytical monitoring:

yes

Details on sampling:

Samples of about 3 mL were taken from 3 control vessels and from each test vessels containing test substance at 0 24, 48 and 72 hours. The samples were stored in the freezer (<=10 °C) until analyses.

Vehicle:

no

Details on test solutions:

PREPARATION AND APPLICATION OF TEST SOLUTION
A stock solution/suspension of the test substance was prepared as follows: an accurately measured amount of 0.6526 g of test substance was dissolved in deionized water. Exactiy 4.0 ml of a 118.5 g/L FeCI3x6H20 was added with a pipette to reach an equimolar concentration of EDTA and Fe(lll). After stirring the pH of the solution was adjusted to pH 5.2 using a 1 M NaOH Solution. The final concentration of 5.1237 g/L based on H4EDTA was reached by adding deionized water to a final volume of 100 mL. The stock Solution was stored in the refrigerator in the dark.
The test solutions were prepared by addition of the required amounts of stock Solution to the test vessels to obtain the following final nominal test concentrations: 60, 80 and 100 mg/L.

Test organisms (species):

Raphidocelis subcapitata (previous names: Pseudokirchneriella subcapitata, Selenastrum capricornutum)

Details on test organisms:

TEST ORGANISM
- Common name: P.subcapitata
- Strain: CCAP 278/4
- Source (laboratory, culture collection): Culture Collection of Algae and Protozoa, Institute of Freshwater Ecology, The Windermere Laboratory, Cumbria, Ambleside, United Kingdom.

Test type:

static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

72 h

Test temperature:

23 ± 2 °C

Salinity:

Not applicable

Nominal and measured concentrations:

Nominal concentrations of 60, 80 and 100 mg/L

Details on test conditions:

TEST SYSTEM
- Test vessel: Erlenmeyer test flasks
- Type (delete if not applicable): open / closed
- Material, size, headspace, fill volume: 100 mL, closed with cotton-wool stoppers

GROWTH MEDIUM
- Standard medium used: yes

OTHER TEST CONDITIONS
- Adjustment of pH: jes
- Light intensity and quality: continuous uniform illumination was provided in the spectral ränge of 400 to 700 nm by using 30 W fluorescent lamps


EFFECT PARAMETERS MEASURED:
- Determination of cell concentrations: photometrically with a UVA/IS Spectrophotometer

Reference substance (positive control):

no

Duration:

72 h

Dose descriptor:

EC50

Effect conc.:

> 100 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

growth rate

Duration:

72 h

Dose descriptor:

EC50

Effect conc.:

> 60 mg/L

Nominal / measured:

meas. (geom. mean)

Conc. based on:

test mat.

Basis for effect:

growth rate

Duration:

72 h

Dose descriptor:

NOEC

Effect conc.:

79.4 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

growth rate

Duration:

72 h

Dose descriptor:

NOEC

Effect conc.:

48.4 mg/L

Nominal / measured:

meas. (geom. mean)

Conc. based on:

test mat.

Basis for effect:

growth rate

Duration:

72 h

Dose descriptor:

LOEC

Effect conc.:

99.9 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

growth rate

Duration:

72 h

Dose descriptor:

LOEC

Effect conc.:

60.6 mg/L

Nominal / measured:

meas. (geom. mean)

Conc. based on:

test mat.

Basis for effect:

growth rate

Validity criteria fulfilled:

yes

Conclusions:

In conclusion the 72 hour EC50 value for Fe(III)EDTA with P.subcapitata was greater than 100 mg/L based on nominal concentrations and greater than 60 mg/L based on the mean measured concentrations. The NOEC was 79.4 mg/L based on nominal concentrations and 48.4 mg/L based on the mean measured concentrations.

Executive summary:

The toxicity of Fe(lll)EDTA to exponentially growing Pseudokirchneriella subcapitata was determined over an exposure period of 72 hours. A test was carried out at nominal concentrations of 60, 80 and 100 mg/L Fe (lll) EDTA (concentrations represented as H4EDTA).Due to photodegradation, the Fe(lll)EDTA concentration declines during the test. The chemical analyses carried out showed that the concentration of the test compound at the end of the test had decreased to about 50 % of the concentration at the beginning of the test. The mean concentrations during the 72 hours of testing for the nominal concentrations of 60, 80 and 100 mg/L as measured by chemical analyses were 38.1, 48.4 and 60.6 mg/L, respectively. The test was conducted in a mineral salt medium in a climatized illuminated orbital incubator. The maximum variation in pH in the test media was 1.4 pH unit. In conclusion the 72 hour EC50-value for Fe(III)EDTA with P.subcapitata was greater than 100 mg/L based on nominal concentrations and greater than 60 mg/L based on the mean measured concentrations. The NOEC was 79.4 mg/L based on nominal concentrations and 48.4 mg/L based on the mean measured concentrations.

Description of key information

Based on the studies it can be stated that the LC50 value for edetic acid is much higher than for nickel salts.

Ammonium cations are know to be non-ecotoxic.

Thus the aquatic toxicity of nickel diammonium ethylenediaminetetraacetate is determined by the nickel moiety of the substance.

The EC50 values obtained from studies on nickel(2 +) salts for algea are > 1 mg/L recalculated EDTA-Ni(NH4)2 by molecular weight correction.

The NOEC values obtained from studies on nickel(2 +) salts for algea are in the range of > 100 µg/L and < 1 mg/L recalculated for EDTA-Ni(NH4)2 by molecular weight correction.

Key value for chemical safety assessment

EC50 for freshwater algae:

1.85 mg/L

EC10 or NOEC for freshwater algae:

272 µg/L