By-product from Guanidinoacetic acid manufacturing

Toxicity to aquatic algae and cyanobacteria

Link to relevant study record(s)

Reference

Endpoint:

effects on growth of green algae

Type of information:

experimental study

Adequacy of study:

key study

Study period:

2020-07-20 - 2021-04-26

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

OECD Guideline 201 (Freshwater Alga and Cyanobacteria, Growth Inhibition Test)

GLP compliance:

yes (incl. QA statement)

Specific details on test material used for the study:

200116MA1 liquid

Analytical monitoring:

yes

Details on sampling:

The samples were taken from the biological phase of the study. Collecting, storage and handing over of the samples were the Study Director’s responsibility. The information concerning the samples was provided by the Study Director.
Four samples from the freshly prepared test media (without algae) of all test concentrations and from the control were taken at the start of the test.
For the determination of the stability of the test item under the test conditions and of the maintenance of the test item concentrations during the test period, four samples from the test media of all test concentrations and the control (containing algae) were taken at the end of the test (after the 72 hours test period) by pouring together the contents of the test beakers of each treatment.
Additionally, four samples per sampling time were taken after 24 und 48 hours of the respective additional vessel of each treatment.
One set of duplicate samples of each sampling point was used for the analysis of DCD and Hydantoic acid. The other set of duplicate samples of each sampling point was used for the determination of total organic carbon (TOC).
All samples remained undiluted.

Test organisms (species):

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

Test type:

static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

72 h

Hardness:

0.24 mmol/L (= 24 mg/L) as CaCO3

Test temperature:

22.4 - 22.9

pH:

pH value in the control at test start: 8.1,
pH value in the control at test end: 10;
pH values in the test item treatments at test start: 7.8 to 8.0,
pH values in the test item treatments at test end: 8.5 to 10.0

Nominal and measured concentrations:

Nominal concentrations:
Control, 0.1, 0.3, 1.0, 3.2, 10.0, 31.6, 100 mg dissolved solids / mL

Analysed % of nominal:
0 h: n.a., 79, 97, 91, 102, 105, 107, 107
72 h: n.a., 81, 94, 92, 100, 102, 105, 102

Reference substance (positive control):

yes

Remarks:

potassium dichromate is tested at least twice a year to demonstrate satisfactory test conditions

Key result

Duration:

72 h

Dose descriptor:

EC50

Effect conc.:

ca. 7.36 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Remarks:

mg dissolved solids / L

Basis for effect:

yield

Key result

Duration:

72 h

Dose descriptor:

EC50

Effect conc.:

> 100 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Remarks:

mg dissolved solids / L

Basis for effect:

growth rate

Validity criteria fulfilled:

yes

Conclusions:

The 72-hour EyC50 was calculated to be 40.9 mg test item/L (7.36 mg dissolved solids/L) and the 72-hour ErC50 value was estimated to be > 556 mg test item/L (> 100 mg dissolved solids/L). The 72-hour NOEyC was determined to be 5.6 mg test item/L (1.0 mg dissolved solids/L) and the associated 72-hour LOEyC was 17.6 mg test item/L (3.2 mg dissolved solids/L). The 72-hour NOErC was determined to be 0.6 mg test item/L (0.1 mg dissolved solids/L) and the associated 72-hour LOErC was 1.8 mg test item/L (0.3 mg dissolved solids/L).

Executive summary:

The influence of the test item “Solution of By-product from Guanidinoacetic acid manufacturing” on the growth of the freshwater green algae Pseudokirchneriella subcapitata was assessed in a static concentration-response test. The 72-hour EyC50 was calculated to be 40.9 mg test item/L (7.36 mg dissolved solids/L) and the 72-hour ErC50 value was estimated to be > 556 mg test item/L (> 100 mg dissolved solids/L). The 72-hour NOEyC was determined to be 5.6 mg test item/L (1.0 mg dissolved solids/L) and the associated 72-hour LOEyC was 17.6 mg test item/L (3.2 mg dissolved solids/L). The 72-hour NOErC was determined to be 0.6 mg test item/L (0.1 mg dissolved solids/L) and the associated 72-hour LOErC was 1.8 mg test item/L (0.3 mg dissolved solids/L). The initial concentrations and the maintenance of the exposure concentrations during the test were verified in the analytical part. Correct dosage was confirmed by the analysis of the component DCD of the test item because DCD is the component with the highest content in the test item. This component is stable under the experimental conditions and does not undergo any reaction with any other component of the test item. Furthermore, a reference substance is commercially available. All reported results refer to nominal values since the concentrations of DCD in the test item were within ± 20% of the nominal concentrations during the test and “Solution of By-product from Guanidinoacetic acid manufacturing” is an UVCB substance (Unknown or Variable composition, Complex reaction products or Biological material).

Description of key information

A GLP Study accoridng OECD TG 201 has been performed to determine the Toxicity of "By-product from Guanindinoacetic acid manufacturing" to Pseudokirchneriella subcapitata in an Algal Growth Inhibition Test.

Effect concentrations refer to mg total dissloved solids / L.

Key value for chemical safety assessment

EC50 for freshwater algae:

100 mg/L

EC10 or NOEC for freshwater algae:

1 mg/L