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Ecotoxicological information

Toxicity to aquatic plants other than algae

Administrative data

Endpoint:
toxicity to aquatic plants other than algae
Type of information:
experimental study
Adequacy of study:
key study
Study period:
From the 3rd of february to the 10th of February, 2017
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study

Data source

Reference
Title:
Unnamed
Year:
2017
Report Date:
2017

Materials and methods

Test guidelineopen allclose all
Qualifier:
according to
Guideline:
OECD Guideline 221 (Lemna sp. Growth Inhibition Test)
Deviations:
no
Qualifier:
according to
Guideline:
other: EU C.26 Commission Regulation (EU) 2016/266 of 7 December 2015
GLP compliance:
yes (incl. certificate)

Test material

Reference
Name:
Unnamed
Type:
Constituent
Test material form:
solid: particulate/powder

Sampling and analysis

Analytical monitoring:
yes
Details on sampling:
At the beginning of the test, as well as after 2, 5 and 7 days

Test solutions

Vehicle:
yes
Details on test solutions:
Since the test item is soluble in Swedish standard-Medium (SIS Medium), the test concentrations were prepared by dilution of a stock solution.
At the nominal concentrations of 31.6 mg/L the test item showed minimal and at 100 mg/L major precipitation, respectively.
The test item did not show any signs of precipitation, at any of the test concentrations.

Test organisms

Test organisms (species):
Lemna minor
Details on test organisms:
TEST ORGANISMS
Exponential growing plant monoculture of Lemna minor (Umweltbundesamt, FGIII 2.5, Überwachungsverfahren Abwasserentsorgung, Schichauweg 58, D-12307 Berlin)
TEST SYSTEM
Culture: All-glass vessel containing sterile Swedish standard-Medium (SIS Medium) and the exponential growing plant monoculture.
Cultivation: At least seven days before testing, sufficient colonies are transferred aseptically into fresh sterile medium and cultured for 7 - 10 days under the conditions of the test
Illumination: Continuous (6500–10000 lux)
Temperature: 24 ± 2 °C

Study design

Test type:
static
Water media type:
freshwater
Remarks:
Recommended Swedish standard-Medium (SIS Medium)
Limit test:
no
Total exposure duration:
7 d

Test conditions

Test temperature:
The temperature ranged between 22.9 and 23.9°C, which is within the required range (24 ± 2°C).
Measured in an additional glass vessel containing SIS medium and Lemna, at least daily.
pH:
6.5 - 7.2
Determined in the combined replicate test solutions at the beginning and at the end of the test.
The pH value in the control drifted by 0.7 units during the whole test period, which is therefore in the range allowed by the guideline (required: not more than 1.5).
Nominal and measured concentrations:
The photometric measurements indicated that the test item concentrations were decreasing. However, all measured concentrations remained in the recommended 80-120% range of the nominal concentration.

500, 158, 50.0, 15.8 and 5.00 mg/L nominal concentrations
corresponding to 302, 95.5, 30.2, 9.55 and 3.02 mg/L, respectively, of the active ingredient.
Details on test conditions:
Test vessels
400 ml beakers, all-glass, with 200 mL of test medium. The beakers are covered with black paper up until the 200 ml mark to ensure that illumination comes only from above and not from the sides.
Illumination: Intensity: continuous (6500–10000 lux), Homogeneity: ±15%.
The light intensity was 6890-9310 lux (mean 7712 lux; max. variation ± 21%) at the start of the test and 6780-9150 lux (mean 7656 lux, max. variation ± 20%) at the end of the exposure period.
The light homogeneity was therefore not in the 15% range. Since the test vessels were randomly replaced and since the growth criterion in the blank control was fulfilled without a too large variation, this deviation is not expected to have any significant impact on the outcome of the study.
Measured at the beginning and at the end of the test over the whole test area at points the same distance from the light source as the Lemna fronds.
Incubation: Beakers will be incubated on a black non-reflecting surface
Reference substance (positive control):
yes
Remarks:
Yearly, with 3,5-dichlorophenol. According to guideline ISO/CD 20079, the ErC50 value based on the frond number should lie in the range 1.8–3.6 mg/l; this level of sensitivity was attained (data from 29 July 2016)

Results and discussion

Effect concentrationsopen allclose all
Duration:
7 d
Dose descriptor:
EC50
Effect conc.:
> 78.4 mg/L
Nominal / measured:
meas. (geom. mean)
Conc. based on:
act. ingr.
Basis for effect:
frond number
Remarks:
growth rate
Duration:
7 d
Dose descriptor:
EC50
Effect conc.:
91.7 mg/L
Nominal / measured:
meas. (geom. mean)
Conc. based on:
act. ingr.
Basis for effect:
frond number
Remarks:
yield
Duration:
7 d
Dose descriptor:
EC50
Effect conc.:
> 78.4 mg/L
Nominal / measured:
meas. (geom. mean)
Conc. based on:
act. ingr.
Remarks:
dry weight
Basis for effect:
other:
Remarks:
growth rate
Duration:
7 d
Dose descriptor:
EC50
Effect conc.:
123 mg/L
Nominal / measured:
meas. (geom. mean)
Conc. based on:
act. ingr.
Remarks:
dry weight
Basis for effect:
other:
Remarks:
yield
Duration:
7 d
Dose descriptor:
NOEC
Effect conc.:
25.1 mg/L
Nominal / measured:
meas. (geom. mean)
Conc. based on:
act. ingr.
Basis for effect:
other: Frond Number: growth rate and yield Dry Weight: growth rate and yield
Details on results:
PRELIMINARY NON-GLP TEST
% inhibition yield of Frond Number: 35% at 100 mg/L nominal concentration (93.4 mg/L measured at the beginning, 55.8% mg/L measured at the end of the test)
% inhibition growth rate of Frond Number: 26% at 100 mg/L nominal concentration (93.4 mg/L measured at the beginning, 55.8% mg/L measured at the end of the test)
The HPLC measurements indicated that the test item concentrations decrease and do not remain in the recommended 80-120% range of the nominal concentration. Nonetheless, the definitive test was performed under static conditions in accordance with the sponsor.

DEFINITIVE TEST
The test concentrations of the substance during the 7-day test period were determined by HPLC analysis. These analyses confirmed that the test item was fully dissolved (82, 85, 89, 92 and 95% of the 1.00, 3.16, 10.0, 31.6 and 100 mg/l nominal concentrations, respectively), and showed that the concentrations decreased over the whole 7-day test period (57, 66, 66, 71, 67% of initial value, respectively). The initial measured test concentrations were 0.818, 2.67, 8.90, 29.1 and 95.4 mg/l and the measured geometric mean concentrations over the whole 7-day test period were 0.662, 2.35, 7.18, 25.1 and 78.4 mg/l, respectively. Therefore, the effective concentrations (ErC50 and EyC50) were assessed based on the measured concentrations of the active ingredient.

The test concentrations during the 7-day test period were determined by HPLC analysis at the beginning of the test, as well as after 2, 5 and 7 days of exposure. These analyses confirmed that the test item was fully dissolved (82, 85, 89, 92 and 95% of the 1.00, 3.16, 10.0, 31.6 and 100 mg/L nominal concentrations, respectively), and showed that the concentrations decreased over the whole 7-day test period (57, 66, 66, 71, 67% of initial value, respectively).
The initial measured test concentrations were 0.818, 2.67, 8.90, 29.1 and 95.4 mg/L and the measured geometric mean concentrations over the whole 7-day test period were 0.662, 2.35, 7.18, 25.1 and 78.4 mg/L, respectively.
Therefore, the effective concentrations (ErC50 and EyC50) were assessed based on the measured concentrations of the active ingredient.

With respect to growth rate inhibition, the following effects as compared to the untreated controls were observed: 18% at 100 mg/L. No significant effects were observed at the nominal concentrations of the active ingredient of 31.6, 10.0, 3.16 and 1.00 mg/L. With respect to yield inhibition, the following effects as compared to the untreated controls were observed: 45% at 100 mg/L. No significant effects were observed at the nominal concentrations of the active ingredient of 31.6, 10.0, 3.16 and 1.00 mg/L.

FROND NUMBER:
50% effects on the growth rate of the frond number could not be attained with the maximal concentration tested here (100 mg/l active ingredient). However, the limited effects observed at this concentration as well as the flat dose-response curve allow to estimate that the 7-day ErC50 on the duckweed Lemna minor for the endpoint frond number is >100 mg/l active ingredient.

Growth rate inhibition:
With respect to growth rate inhibition, the following effects as compared to the untreated controls were observed: 16% at 100 mg/L. No significant effects were observed at the nominal concentrations of the active ingredient of 31.6, 10.0, 3.16 and 1.00 mg/L.
Yield:
With respect to yield inhibition, the following effects as compared to the untreated controls were observed: 38% at 100 mg/L. No significant effects were observed at the nominal concentrations of the active ingredient of 31.6, 10.0, 3.16 and 1.00 mg/L.

DRY WEIGHT
50% effects on the growth rate of the dry weight could not be attained with the maximal concentration tested here (100 mg/L active ingredient). However, the limited effects observed at this concentration as well as the flat dose-response curve allow to estimate that the 7-day ErC50 on the duckweed Lemna minor for the endpoint dry weight is >100 mg/l active ingredients.

APPEARANCE OF THE PLANTS
In the blank control and at the nominal concentrations of 1.00 and 10.0 mg/L, the plants were healthy with green fronds and roots reaching to the bottom of the test vessel.
At the nominal concentration of 3.16 mg/l, the plants did not appear any different from the blank controls, except for 4 fronds, which appeared yellow. This discoloration was only observed in 4 out of almost 600 fronds, and therefore, can be considered insignificant. At the nominal concentration of 31.6 mg/L, the plants were healthy with green fronds.
Nevertheless, they were slightly smaller and the roots were 5 mm shorter as compared to the blank controls. At the nominal concentration of 100 mg/L, the plants were healthy with green fronds. They were more compact and smaller and the roots were 5 mm shorter as compared to the blank controls.

Any other information on results incl. tables

Environmental condition:

The light intensity was 7120-8820 lux (mean 7863 lux; max. variation±12%) at the start of the test and 7200-8710 lux (mean 7872 lux, max. variation±11%) at the end of the exposure period. The light homogeneity was therefore in the required ± 15% range.

In the blank control the plants were healthy with dark green fronds and roots reaching to the bottom of the test vessel.

At 3.02, 9.55 and 30.2 mg/L, the plants looked like the blanks, with dark green fronds and roots reaching to the bottom of the test vessel.

At 95.5 mg/L, the plants were healthy with dark green fronds and roots reaching to the bottom of the test vessel. Compared to the blanks, the plants were smaller.

At 302 mg/L, the plants had many fronds, which were partly light green to yellow discolored; the roots were very short.

The dry weight data showed an unusual variation, which cannot be explained. The statistical analysis is therefore yielding large confidence intervals. However, since all requirements of the test guideline were fulfilled, and especially since the data of the variable frond number presented were highly reliable, the test was deemed as valid.  

Frond number, growth rate inhibition:

the following effects as compared to the untreated controls were observed: 49% at 302 mg/L, 9% at 95.5 mg/L and 5% at 30.2 mg/L. No significant effects were observed at 9.55 mg/L and 3.02 mg/L.

Frond number,yield inhibition:

the following effects as compared to the untreated controls were observed: 76% at 302 mg/L, 23% at 95.5 mg/L, 12% at 30.2 mg/L and 8% at 9.55 mg/L. No significant effects were observed at 3.02 mg/L.

Dry weight, growth rate inhibition:

the following effects as compared to the untreated controls were observed: 70% at 302 mg/l, 50% at 95.5 mg/l, 39% at 30.2 mg/l and 44% at 9.55 mg/l. No significant effects were observed at 3.02 mg/L.

Dry weight,yield inhibition:

the following effects as compared to the untreated controls were observed: 86% at 302 mg/l, 70% at 95.5 mg/l, 59% at 30.2 mg/l and 64% at 9.55 mg/l. No significant effects were observed at 3.02 mg/L.

The median effect concentration with respect to the frond number’s growth rate (frond number ErC50) to Lemna minor was calculated to be 313 mg/L (95% confidence limits: 288–346 mg/l). The ErC10 was 91.9 mg/L (69.8–111 mg/L); while the NOErC was determined to be 9.55 mg/L.

The median effect concentration with respect to the frond number’s yield (frond number EyC50) to Lemna minor was calculated to be 169 mg/L (95% confidence limits: 143–201 mg/L). The EyC10 was 49.0 mg/L (31.1– 65.2 mg/L); while the NOEyC was determined to be 3.02 mg/L.

The median effect concentration with respect to the dry weight’s growth rate (dry weight r ErC50) to Lemna minor was calculated to be 55.2 mg/L (95% confidence limits: 3.69–2709 mg/L). No ErC10 could be calculated; while the NOErC was determined to be 3.02 mg/L.

The median effect concentration with respect to the dry weight’s yield (dry weight EyC50) to Lemna minor was calculated to be 6.90 mg/L (95% confidence limits: not determined–31.1 mg/l). No ErC10 could be calculated; while the NOEyC was determined to be 3.02 mg/L.

Applicant's summary and conclusion

Validity criteria fulfilled:
yes
Remarks:
The doubling time of frond number in the control must be less than 2.5 days (60 h), corresponding to approximately a seven-fold increase in seven days and an average specific growth rate of 0.275 d-1
Conclusions:
ErC50 frond number, on duckweed Lemna minor (7 days) 313 mg/L active ingredient (iron complexes, sodium salt)
ErC50 dry weight, on duckweed Lemna minor (7 days) 55.2 mg/L active ingredient (iron complexes, sodium salt)
NOrEC frond number, growth rate on duckweed Lemna minor (7 days) 9.55 mg/L active ingredient (iron complexes, sodium salt)
NOrEC dry weight, growth rate on duckweed Lemna minor (7 days) 3.02 mg/L active ingredient (iron complexes, sodium salt)
Executive summary:

Method

The inhibitory effects of the substance to the duckweed Lemna minor were investigated over a period of 7 days, based on the frond number and biomass (dry weight), following the guideline OECD 221. The test item is solid, has a high solubility (37.98 ± 2.89 g/l at 20.0 ± 0.5 °C) and is 60.42 % pure. Therefore,the test solutions were prepared by respective dilutions of a stock solution in Swedish standard-Medium (SIS Medium).

The test was performed at 500, 158, 50.0, 15.8 and 5.00 mg/L nominal concentration, corresponding to 302, 95.5, 30.2, 9.55 and 3.02 mg/L, respectively, of the active ingredient.

Three parallel test vessels were used for each test concentration of the test item and six vessels for the blank controls.

The test concentrations during the 7-day test period weredetermined byphotometryat the beginning of the test, as well as after 3, 5 and 7 days of exposure. These analyses confirmed the right dosage of the test item, and showed that the concentrations of the test item were maintained satisfactorily over the whole 7-day test period and remained within 80-120% of the nominal concentrations. Therefore, the effective concentrations (ErC50and EyC50) were assessed based on the nominal concentrations of the active ingredient.

The two endpoints frond number and biomass (dry weight) were investigated at days 3, 5 and 7, and each of them were assessed as growth rate and yield.

Observations

Frond number, growth rate inhibition:

the following effects as compared to the untreated controls were observed: 49% at 302 mg/L, 9% at 95.5 mg/L and 5% at 30.2 mg/L. No significant effects were observed at 9.55 mg/L and 3.02 mg/L.

Frond number, yield inhibition:

the following effects as compared to the untreated controls were observed: 76% at 302 mg/L, 23% at 95.5 mg/L, 12% at 30.2 mg/L and 8% at 9.55 mg/L. No significant effects were observed at 3.02 mg/L.

Dry weight, growth rate inhibition:

the following effects as compared to the untreated controls were observed: 70% at 302 mg/l, 50% at 95.5 mg/l, 39% at 30.2 mg/l and 44% at 9.55 mg/l. No significant effects were observed at 3.02 mg/l.

Dry weight, yield inhibition:

the following effects as compared to the untreated controls were observed: 86% at 302 mg/l, 70% at 95.5 mg/l, 59% at 30.2 mg/l and 64% at 9.55 mg/l. No significant effects were observed at 3.02 mg/l.

Conclusion

Frond number, growth rate inhibition:

ErC50 to Lemna minor was calculated to be 313 mg/L (95% confidence limits: 288–346 mg/L). 

The ErC10 was 91.9 mg/L (69.8–111 mg/L);

NOErC was determined to be 9.55 mg/L.

Frond number, yield inhibition:

EyC50 to Lemna minor was calculated to be 169 mg/L (95% confidence limits: 143–201 mg/L). 

The EyC10 was 49.0 mg/L (31.1–65.2 mg/L);

NOEyC was determined to be 3.02 mg/L.

Dry weight, growth rate inhibition:

ErC50 to Lemna minor was calculated to be 55.2 mg/L (95% confidence limits: 3.69–2709 mg/L).

No ErC10 could be calculated;

NOErC was determined to be 3.02 mg/L.

Dry weight, yield inhibition:

EyC50 to Lemna minor was calculated to be 6.90 mg/L (95% confidence limits: not determined–31.1 mg/L).

No ErC10 could be calculated;

NOEyC was determined to be 3.02 mg/L.