Glycollic acid

Short-term toxicity to aquatic invertebrates

Link to relevant study record(s)

Reference

Reference 1

Endpoint:

short-term toxicity to aquatic invertebrates

Type of information:

experimental study

Adequacy of study:

key study

Study period:

19 February to 28 May, 2021

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)

Version / remarks:

April 13, 2004

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Analytical monitoring:

yes

Details on sampling:

Duplicate samples from the freshly prepared test medium of the 100 mg/L test concentration and the control were taken at the start of the test and test medium renewal after 24 hours. To determine test item stability under the test conditions and the maintenance of the test item concentration during the renewable periods, duplicate samples were also taken at the test medium renewal and at the end of the test from all aged test media and the control of the actual test by pooling the contents of beakers of all replicates for each treatment. All samples remained undiluted until sample preparation. All samples were stored in a freezer (≤ -20 °C), protected from light, until analysis was performed. Afterwards the samples were again stored deep frozen and will be kept stored up to the date of the final report.

Vehicle:

no

Details on test solutions:

The test medium of the only test item concentration of nominal 100 mg/L was prepared by dissolving 52.9 and 49.3 mg test item into 529- and 493-mL test water by intense stirring for 10 to 30 minutes. The pH of the test medium of the test item concentration was adjusted from pH 4.2 to 7.6 (day 0) and pH 4.1 to 8.7 (day 1) using 2 M NaOH. The test media was prepared just before introduction of the daphnids (start of the test) and test medium renewal on Day 1.

Test organisms (species):

Daphnia magna

Details on test organisms:

Species: Daphnia magna (Straus), clone 5;
Age at Test Start: From 5.25 to 23.25 hours old;
Origin: Test organisms were from the in-house laboratory culture;
Breeding Conditions: Daphnids were bred in the testing laboratory under similar temperature and light conditions as used in the test. The cultivation of the parental daphnids was performed in Eland M4 medium. Test organisms were not first brood progeny. The daphnids in the stock culture were fed at least on all working days with green algae (Desmodesmus subspicatus) freshly grown in the testing laboratory.
Acclimatisation: Was not necessary, since the test and culturing were performed in the same medium.

Test type:

semi-static

Water media type:

freshwater

Limit test:

yes

Total exposure duration:

48 h

Remarks on exposure duration:

No further remarks

Post exposure observation period:

Not applicable

Hardness:

2.5 mmol/L (= 250 mg/L) as CaCO3

Test temperature:

18.8 to 19.8 °C in freshly prepared media;
19.7 to 20.0 °C in aged test media

pH:

7.7 to 8.6 in freshly prepared media;7.8 to 7.9 in aged test media

Dissolved oxygen:

8.9 to 9.3 mg/L in freshly prepared media;
8.7 to 8.8 mg/L in aged test media

Salinity:

Not applicable

Conductivity:

Not reported

Nominal and measured concentrations:

Nominal: 0 (control), 100 mg/L (pH adjusted)

Details on test conditions:

Tests were conducted in 100 mL glass beakers containing approximately 60mL of test medium. Test vessels were covered with a lid to reduce the loss of water due to evaporation and to avoid the entry of dust into the solutions. Reconstituted water (Elendt "M4") was prepared according to SOP with deionised water in which analytical grade salts and additives were added at the appropriate nominal concentrations.

Pre-experiments were performed to determine a suitable concentration range and to establish suitable methods to prepare the test solutions.

In the definitive test, 20 daphnids were introduced per control and test concentration, divided into 4 groups of 5 animals, each group in one test vessel. The test was performed with four replicates per treatment group. Test organisms were not fed during the testing period. Test medium was renewed on day 1 to keep the test item concentrations in the test media as constant as possible in the test media.

Tests were conducted within a controlled environmental room. The water temperature, pH-values and the dissolved oxygen concentrations were determined daily in the freshly prepared and aged test media of each treatment group. A photoperiod of 16:8 hours light: darkness (light intensity: 340 to 390 Lux) was provided.

The mobility of the daphnids was determined by visual observation after 24 and 48 hours. Animals that were unable to swim within 15 seconds after gentle agitation of the test beaker were immobile (even if they could still move their antennae). Any signs of disease or stress or unusual behaviour were documented in the raw data.

Reference substance (positive control):

yes

Remarks:

Potassium dichromate (tested at least twice a year)

Duration:

48 h

Dose descriptor:

NOEC

Effect conc.:

>= 100 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

mobility

Duration:

24 h

Dose descriptor:

LOEC

Effect conc.:

> 100 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

mobility

Duration:

24 h

Dose descriptor:

EC50

Effect conc.:

> 100 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

mobility

Duration:

48 h

Dose descriptor:

LOEC

Effect conc.:

> 100 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

mobility

Key result

Duration:

48 h

Dose descriptor:

EC50

Effect conc.:

> 100 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

mobility

Details on results:

No immobilisation of the test animals was observed in the control after 48-hours of exposure and dissolved oxygen concentration at test end: ≥ 8.7 mg O2/L, thus all validity criteria were met. In the freshly prepared test media at the start of the test and at the renewal of the test media, 106% of the nominal test concentration were found. In the aged test media after 24 hours test duration, 105 % of the nominal value was determined. During the test the test organism were exposed to a mean of 106 % of nominal. Results therefore refer to nominal values, since the concentrations of the test item were within ± 20% of the nominal concentrations during the test. At the only concentration of 100 mg/L, one animal was immobile after 48-hours of exposure.

Results with reference substance (positive control):

The most recent test with the reference substance (potassium dichromate) resulted in 24- and 48-hour EC50 values of 0.918 and 0.685 mg/L, respectively. The results indicate that the sensitivity of the daphnids was consistent with the level proposed by the OECD 202 guideline (EC50-24 h between 0.6 and 2.1 mg potassium dichromate/L).

Reported statistics and error estimates:

No statistical analysis was performed. The EC50 could not be quantified due to the absence of toxicity of the test item and were determined to be higher than the highest test concentration. The NOEC and the LOEC were determined directly from the raw data.

Influence of Glypure™ 99 on the Mobility of Daphnia magna and sublethal effects

Nominal concentration [mg test item/L]	No. of Daphnia tested	No. of immobilised Daphnia after		% of immobilised Daphnia after		Observations
		24 h	48 h	24 h	48 h	24 h	48 h
Control	5	0	0	0	0	0	0
	5	0	0			0	0
	5	0	0			0	0
	5	0	0			0	0
100	5	0	0	0	5	0	0
	5	0	1			AA (1)	0
	5	0	0			0	0
	5	0	0			0	0

0: No abnormalities;

AA: Agglutinated antennae;

In parenthesis number of daphnia with sublethal effects

 

 

Summary of Analytical Results

Sample description [mg test item/L]	Fresh (0 h)			Aged (24 h)			Overall
	% of nominal^1	RSD [%]	n	% of nominal^1	RSD [%]	n	% of nominal^1	RSD [%]	n
Control	n.a.	n.a.	4	n.a.	n.a.	4	n.a.	n.a.	8
100	106	2	4	105	3	4	106	2	8

¹ mean value of all measured samples per treatment group

RSD: relative standard deviation per treatment group

n: number of analysed samples

n.a.: not applicable

 

 

Temperature [°C] in the Test Media

Nominal concentration [mg test item/L]	Water temperature [°C]
	0 h	24 h (aged)	24 h (fresh)	48 h
Control	19.2	19.7	18.8	19.9
100	19.8	19.7	19.6	20.0

 

 

Dissolved Oxygen Concentrations and pH-Values in the Test Media

Nominal concentration [mg test item/L]	0 h		24 h (aged)		24 h (fresh)		48 h
	pH	O2 [mg/L]	pH	O2 [mg/L]	pH	O2 [mg/L]	pH	O2 [mg/L]
Control	8.0	8.9	7.9	8.8	7.9	9.3	7.9	8.7
100	7.7	9.0	7.8	8.7	8.6	8.9	7.9	8.7

 

Validity criteria fulfilled:

yes

Conclusions:

The 48-hour EC50 and LOEC were determined to be >100 mg/L (pH adjusted), the 48-hour NOEC was determined to be ≥100 mg/L (pH adjusted). Results were based on nominal values since the concentrations of the test item were within ± 20% of the nominal concentrations during the test.

Executive summary:

The acute toxicity of Glypure™ 99 to Daphnia magna was assessed according to OECD Guideline 202.

 

Young daphnids (< 24 hours old) were exposed in a semi-static test to a nominal test item concentration of 100 mg/L (pH adjusted) and a control for 48-hours. The number of immobile organisms were after 24 and 48 hours.

 

In the freshly prepared test media at the start of the test and at the renewal of the test media, 106% of the nominal test concentration were found. In the aged test media after 24 hours test duration, 105 % of the nominal value was determined. During the test the test organism were exposed to a mean of 106 % of nominal. Results therefore refer to nominal values, since the concentrations of the test item were within ± 20% of the nominal concentrations during the test.

 

No immobilisation of the test animals was observed in the control after 48-hours of exposure anddissolved oxygen concentration at test end: ≥ 8.7 mg O₂/L, thus all validity criteria were met.

 

At the only concentration of 100 mg/L, one animal was immobile after 48-hours of exposure. The 48-hour EC50 and LOEC were determined to be >100 mg/L (pH adjusted), the 48-hour NOEC was determined to be ≥100 mg/L (pH adjusted).

Reference 2

Endpoint:

short-term toxicity to aquatic invertebrates

Type of information:

experimental study

Adequacy of study:

supporting study

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

test procedure in accordance with national standard methods with acceptable restrictions

Qualifier:

according to guideline

Guideline:

other: UK Proposal to ISO/TC 147/SC5/WG2 Water Quality – Determination of acute lethal toxicity to marine copepods (Copepoda, Crustacea), Second Draft 1990

GLP compliance:

yes

Analytical monitoring:

no

Vehicle:

no

Test organisms (species):

other aquatic crustacea: Acartia tonsa (Dana)

Test type:

static

Water media type:

saltwater

Limit test:

no

Total exposure duration:

48 h

Reference substance (positive control):

yes

Remarks:

3,5-dichlorophenol

Duration:

48 h

Dose descriptor:

NOEC

Effect conc.:

83.5 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

mortality

Duration:

24 h

Dose descriptor:

EC50

Effect conc.:

264 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

mortality

Remarks on result:

other: 95% CL 227 – 426 mg/L

Duration:

48 h

Dose descriptor:

EC50

Effect conc.:

226 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

mortality

Remarks on result:

other: 95%CL 174 – 260 mg/L

There was 100% immobility in the 716 and 2227 mg/L treatments.  The lowest concentration showing mortality was 247 mg/L after 24 and 48 hours (LOEC) and the highest concentration showing no mortality was 83.5 mg/L (NOEC).

Validity criteria fulfilled:

yes

Conclusions:

Based on nominal exposure concentrations the 48-hour EC50 value for Acartia tonsa exposed to glycolic acid 70% solution was 226 mg/L (equivalent to 158.2 mg a.s./L) and the corresponding NOEC was 83.5 mg/L (equivalent to 58.5 mg a.s./L).

Executive summary:

The acute toxicity of glycolic acid 70% solution to the marine copepod Acartia tonsa, under static test conditions, was investigated according to the UK Proposal to ISO/TC 147/SC5/WG2 Water Quality – Determination of acute lethal toxicity to marine copepods (Copepoda, Crustacea) (second draft 1990). Based on nominal exposure concentrations the 48-hour EC50 value for Acartia tonsa exposed to glycolic acid 70% solution was 226 mg/L (equivalent to 158.2 mg a.s./L) and the corresponding NOEC was 83.5 mg/L (equivalent to 58.5 mg a.s./L).

Description of key information

Studies assessing the acute toxicity of glycolic acid to aquatic invertebrates are available. The key 48-hour EC50 value (due to being the most conservative and reliable data available) was >100 mg/L (based on nominal test concentrations), shown in Daphnia magna (Bebon and Sonntag, 2021a). This key study was GLP compliant and met all validity criteria of the study guideline (OECD guideline 202).

Additional information

The experimental study performed by Haskell Laboratory for Toxicology and Industrial Medicine in 2000 was disregarded and invalidated. The pH was outside the acceptable range of 6 to 9. The pH was reported between 6.9 to 7.8 in the control group and at 25, 50 and 100 mg/L and decreased at 3.0-3.8 at 200, 400 and 800 mg/L where 100% immobility were observed. Effects observed could be attributed due to the strong acidic properties of the test substance.