Glyoxylic acid

Toxicity to terrestrial arthropods

Administrative data

Endpoint:

toxicity to terrestrial arthropods: long-term

Data waiving:

study scientifically not necessary / other information available

Justification for data waiving:

other:

Justification for type of information:

JUSTIFICATION FOR DATA WAIVING
Short and long term terrestrial studies have not been conducted since direct and indirect exposure of the soil compartment is not expected considering the properties of the molecule.
It is highly water soluble (1000 g/L and consequently has a very low sorption potential to soil), it is poorly volatile (HLC=3.02E-4 Pa-m3/mole at 25°C), it is readily biodegradable and has proved to exert no toxicity effect at the highest concentration tested (100 mg/L) in acute toxicity tests performed on fish, daphnia and algae. Consequently exposure to soil and effect regarding the terrestrial compartment are not expected.

Cross-reference

Cross-reference 1

Reason / purpose for cross-reference:

data waiving: supporting information

Reference

The water solubility of Gloxylic Acid was calculated with the WATERNT program and resulted in a value of 1e06 mg/L at 25°C.

Qualitative data on the water solubility of Glyoxylic Acid 50% is available from literature, indicating very high solubility in water. Additionally the water solubility of Glyoxylic Acid 50% was calculated as 1e06 mg/L by using WATERNT program (2008) from Epiweb 4.0, which is supported by the available literature data.

Cross-reference 2

Reason / purpose for cross-reference:

data waiving: supporting information

Reference

Endpoint:

Henry's law constant

Type of information:

(Q)SAR

Adequacy of study:

key study

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

accepted calculation method

GLP compliance:

no

H:

0 Pa m³/mol

Temp.:

25 °C

Conclusions:

HENRYs law constant was calculated according to Henrywin v3.10 program: 3.02E-4 Pa-m3/mole at 25°C

Cross-reference 3

Reason / purpose for cross-reference:

data waiving: supporting information

Reference

Endpoint:

biodegradation in water: ready biodegradability

Type of information:

experimental study

Adequacy of study:

key study

Study period:

From 18. May to 02. June 2009

Reliability:

1 (reliable without restriction)

Qualifier:

according to guideline

Guideline:

OECD Guideline 301 A (Ready Biodegradability: DOC Die Away Test)

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Remarks:

Harlan Laboratories Ltd., Quality Assurance GLP, Zelgliweg 1, 4452 Itingen, Switzerland

Oxygen conditions:

aerobic

Inoculum or test system:

activated sludge, domestic, non-adapted

Details on inoculum:

- Source of activated sludge:
wastewater treatment plant (ARA Ergolz II, Füllinsdorf / Switzerland) treating predominantly domestic wastewater
- Storage conditions:
room temperature
- Pretreatment:
The sludge was washed twice with tap water by centrifugation and the supernatant liquid phase was decanted. A homogenized aliquot of
the final sludge suspension was weighed, thereafter dried and the ratio of wet to dry weight was calculated
- Concentration of sludge:
30 mg dry material per liter

Duration of test (contact time):

14 d

Initial conc.:

30.4 mg/L

Based on:

DOC

Parameter followed for biodegradation estimation:

DOC removal

Reference substance:

benzoic acid, sodium salt

Parameter:

% degradation (DOC removal)

Value:

98

St. dev.:

2.8

Sampling time:

3 d

Validity criteria fulfilled:

yes

Interpretation of results:

readily biodegradable

Conclusions:

Due to the fact that > 98 % of Glyoxylic Acid 50 % were degraded within the 10-d window of the incubation period, the test item can be classified as readily biodegradable under the conditions of this study.

Executive summary:

In a Ready Biodegradability study (OECD 301 A) Glyoxylic Acid 50% was assessed over a 14 day period by the DOC die away test. The nominal test concentration was 30.4 mg/L. The test material attained > 98 % biodegradation after 3 and 10 days, respectively. The reference compound sodium benzoate showed a mean biodegradability of > 90 % within 7 days, thus confirming suitability of the activated sludge.

These results indicate that Glyoxylic Acid 50% is readily biodegradable under conditions of the test.

Cross-reference 4

Reason / purpose for cross-reference:

data waiving: supporting information

Reference

Endpoint:

short-term toxicity to fish

Type of information:

experimental study

Adequacy of study:

key study

Study period:

2007

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

EU Method C.1 (Acute Toxicity for Fish)

Deviations:

no

Qualifier:

according to guideline

Guideline:

OECD Guideline 203 (Fish, Acute Toxicity Test)

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Remarks:

RCC Ltd - Zelgliweg 1 - 4452 Itingen/Switzerland

Analytical monitoring:

yes

Test organisms (species):

Danio rerio (previous name: Brachydanio rerio)

Details on test organisms:

The study was performed with zebra fish (Brachydanio rerio). The test fish were raised in the RCC Laboratories without any medication. Prior to test start, they were acclimated for one week to the test water and temperature. During holding and acclimatization until one day before the start of the test the fish were fed with a commercial fish diet (Tetra Min(r) Hauptfutter, supplied by Tetra-Werke - Germany). During the last two weeks prior to the test no fish died in the test fish batch and all fish were healthy.
From the acclimated test fish batch, 10 fish were measured at the start of the test. The mean body length of the fish was 3.3 +/- 0.07 cm (Mean +/- SD), the mean body wet weight was 0.24 +/- 0.01 g (Mean +/- SD).

Test type:

semi-static

Water media type:

freshwater

Limit test:

yes

Total exposure duration:

96 h

Post exposure observation period:

96 h

Hardness:

1.25 mmol/L (125 as CaCo3 mg/L)

Test temperature:

21-22 °C during the test period

pH:

The pH values in the test medium and the control ranged during the test period from 6.8 to 7.2 (the pH value after adjustement at each test item application was 7.1).

Dissolved oxygen:

The oxygen concentration was always 7.8 mg/L or higher and thus higher than 60 % oxygen saturation

Nominal and measured concentrations:

200 mg/L

Details on test conditions:

TEST SYSTEM
- Test vessel:
- glass aquarium with 5 liters of test medium was used for each treatment
- Aeration: the test medium and the controls were slightly aerated during the test period
- Renewal rate of test solution: during the test the fish were transferred daily into a clean test vessel with freshly prepared test medium
- No. of organisms per vessel: 7
- Biomass loading rate: less than 1 g fish wet weigt per liter

TEST MEDIUM / WATER PARAMETERS
- Source/preparation of dilution water: at the start of the test and before each test medium renewal, the test medium of nomial 200 mg/L was freshly prepared by completely dissolving 1000 mg (dosing range: 1000.0-1000.5 mg) of the test item in 5 liters of test water using satirring for 15 minutes at room temperature


OTHER TEST CONDITIONS
- Adjustment of pH: with 6.2-6.5 mL of a 1 M sodium hydroxide solution
- Photoperiod: 16-hours light t 8-hours dark period (30 minutes transition)
- Light intensity: 50-500 Lux

Reference substance (positive control):

yes

Remarks:

test water without addition of the test item

Duration:

96 h

Dose descriptor:

LC50

Effect conc.:

> 200 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

mortality (fish)

Duration:

96 h

Dose descriptor:

LC0

Effect conc.:

> 200 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

mortality (fish)

Duration:

96 h

Dose descriptor:

NOEC

Effect conc.:

> 200 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

other: observations

Details on results:

In the control and in the test medium with the nominal concentration of 200 mg/L (= Glyoxylic acid 100.3 mg/L) all fish survived until the end of the test and no visible abnormalities were observed at the test fish. Therefore, the 96-h NOEC and the 96-h LC0 were determined to be at least 200 (100.3 ) mg/L. The 96-h NOEC and the 96-h LC0 might even be higher than this concentration, but concentration in excess of 200 (100.3) mg/L have not been tested.
The 96-h LOEC, the 96-h LC50 and the 96-h LC100 were clearly higher than 200 (100.3) mg/L. These values could no be quantified due to the absence of toxicity of Glyoxylic acid 50 % at the tested concentration.
No remarkable observation were made concerniong the appearance of the test medium. It was a clear solution throught the entire test duration.

Sublethal observations / clinical signs:

In the analyzed test medium samples from the start and end of the first and last test medium renewal periods the measured test item concentrations ranged between 103 and 114% of the nominal value. Consequently, the test water renewal ensured nearly constant concentration of the test item during the test and the reported biological results are related to the nominal test item and Glyoxylic acid (in brackets) concentration.

Validity criteria fulfilled:

yes

Conclusions:

The 96-hour LC50 in Zebra fish is > 200 mg/L (Glyoxylic acid 50 % ) or > 100.3 mg/L (Glyoxylic Acid).

Executive summary:

The acute toxicity of the test item Glyoxylic acid 50% to zebra fish (Brachydanio rerio) was determined in a 96 -hour semi-static test with a daily test medium renewal according to the EU Commission Directive 92/69/EEC, Part C.1 (1992) and the OECD Guideline for Testing of Chemicals No 203, (1992). A limit test was performed in accordance with the guideline to demonstrate the test item Glyoxylic acid 50% has no toxic effect on the test organisms at the nominal concentration of 200 mg/L and a control.

In the control and in the test medium with the nominal concentration of 200 mg/L Glyoxylic Acid 50% (= 100.3 mg/L Glyoxylic Acid) all fish survived until the end of the test and no visible abnormalities were observed at the test fish.

Therefore, the 96-hour NOEC (highest concentration tested without toxic effects after the exposure period of 96 hours), and the 96-hour LC0 were determined to be at least 200 (100.3) mg/L. the 96-hour NOEC and the 96-hour LC0 might even be higher than this concentration, but concentrations in excess of 200 (100.3) mg/L have not been tested. The 96 -hour LOEC (lowest concentration with toxic effects), the 96-hour LC50 and the 96-hour LC100 were clearly higher than 200 (100.3) mg/L. These values could not be quantified due to the absence of toxicity of Glyoxylic acid 50% at the tested concentration.

Cross-reference 5

Reason / purpose for cross-reference:

data waiving: supporting information

Reference

Endpoint:

short-term toxicity to aquatic invertebrates

Type of information:

experimental study

Adequacy of study:

key study

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

EU Method C.2 (Acute Toxicity for Daphnia)

Deviations:

no

Qualifier:

according to guideline

Guideline:

OECD Guideline 202 (Daphnia sp. Acute Immobilisation Test)

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Remarks:

RCC Ltd - Zelgliweg 1 - 4452 Itingen/Switzerland

Analytical monitoring:

yes

Details on sampling:

For the determination of the actual test item concentrations, duplicate samples were taken from each treatment befor the start of the test and at the end of the test after 48 hours.
For the 48-hour stability samples, the contents of the respective replicates were combined prior to sampling.
All samples were stored deep-frozen (at about -20 °C) immediately after sampling.

Vehicle:

yes

Details on test solutions:

The test medium of the highest nominal concentration of 200 mg/L was prepared by dissolving 301.7 mg of test item completely in 1500 mL of test water using intense stirring for 15 minutes at room temperature. Adequate volumes of this test medium were diulted with test water to prepare the test media with the lower test item concentrations. The test media were prepared just before introduction of the daphnids (i.e., start of the test).

Test organisms (species):

Daphnia magna

Details on test organisms:

The study was performed with young daphnids of the species Daphnia magna Straus. A clone of this species (defined by the supplier as clone 5) was originally supplied by the University of Sheffield/UK in 1992. Since that time, the clone has been bred in the Laboratories of RCC in reconstitued water of the quality identical to the water quality used in the tests (in respect to pH, main ions, and total hardness) and under temperature and light conditiosn identical to those of the test. A the start of the test, the organisms used in the test were 6-24 hours old and were not first brood progeny.
For evaluation of the quality of the daphnia clone and the experimental conditions, potassium dichromate is tested as a positive control twice a year.

Test type:

static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

48 h

Post exposure observation period:

48 h

Hardness:

2.5

Test temperature:

20 °C

pH:

The pH of the test medium with the highest test concentration of nominal 200 mg/L was 4.0 after the test item application. The pH was adjusted to 6.2 with 25 drops of a 1 M sodium hydroxide solution.

Nominal and measured concentrations:

The following nonimal concentrations of Glyoxylic acid 50 % were tested: 9.3, 20, 43, 93 and 200 mg/L.
Additionally, a control was tested in parallel (test water without test item). Nominal concentrations above 200 mg/L were not tested.

Details on test conditions:

For each treatment, 20 daphnids were used divided into four replicates of five daphnids each.
The volume of test solution provided for each daphnia was 10 mL. Thus, the requirement of the test guidelines for the minimum volume of 2 mL test medium per daphnia was fulfilled. The daphnids were randomly distributed to the test vessels at initiation of the test.
For further information see section "Any other information on materials and methods incl. tables".

Reference substance (positive control):

yes

Remarks:

potassium dichromate

Duration:

48 h

Dose descriptor:

NOEC

Effect conc.:

200 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Duration:

48 h

Dose descriptor:

EC0

Effect conc.:

200 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Duration:

48 h

Dose descriptor:

EC50

Effect conc.:

> 200 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Duration:

48 h

Dose descriptor:

EC100

Effect conc.:

> 200 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Duration:

48 h

Dose descriptor:

NOEC

Effect conc.:

> 200 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Details on results:

The analytically determined concentration of the test item in the analyzed test medium (nominal 200 mg/L test item) at the start and the end of the test was 85 and 81 % of the nominal value, respectively. Under the conditions of the test, the test item Glyoxylic acid 50 % was sufficiently stable during the test period of 48 h.
Therefore, all reported results are related to the nominal concentration of the test item Glyoxylic acid 50 % and Glyoxylic acid (concentration in brackets).
In the control and at the test concentrations up to and including the nominal concentration of 200 mg/L (100.3 mg/L), no immobilized test organisms were observed during the test period of 48 hours.
Therefore, the 48-hour NOEC and the 48-hour EC0 to Daphnia magna were determined to be at least 200 (100.3) mg/L.
The 48-hour NOEC and the 48-hour EC0 might even be higher but concentrations above 200 (100.3) mg/L. The 48-hour EC50 and the 48-hour EC100 were clearly hiher than 200 (100.3) mg/L.
These values could not be quantified due to the absence of toxicity at the test concentration up to and including the nominal concentration of 200 (100.3) mg/L.
No remarkable observations were made concerning the appearance of the test media. All test media were clear solutions throughout the entire test duration.
At the beginning and the end of the test period, the dissolved oxygen concentrations in the test media and the control were at least 8.1 mg/L, the pH value of the test medi was in the range of 6.2 to 7.8 (after adjustment) and the water temperature during the test was in the range of 20°C.

Results with reference substance (positive control):

For evaluation of the quality of the daphnia clone and the experimental conditions, potassium cichromate is tested as a positive control twice a year.
- Results with reference substance valid: yes, (historical range of the RCC laboratory 1996-2007: 48-h EC50 : 0.53-1-1 mg/L)
- EC50/LC50: 0.84 mg/L (last test June 2007)

Validity criteria fulfilled:

yes

Conclusions:

The 48-hour NOEC and the 48-hour EC0 to Daphnia magna were determined to be at least 200 (100.3) mg/L.
The 48-hour EC50 and the 48-hour EC100 were clearly higher than 200 (100.3) mg/L.
These values could not be quantified due to the absence of toxicity at the test concentration up to and including the nominal concentration of 200 (100.3) mg/L

Executive summary:

The acute toxicity of the test item Glyoxylic acid 50 % to Daphnia magna was determined in a 48 -hour static test according to the EU Commission Directive 92/69/EEC, Part C.2 (1992) and the OECD Guideline for Testing of Chemicals, No 202 (2004).

The nominal test item (Glyoxylic acid 50 %) concentrations tested were 9.3, 20, 43, 93 and 200 mg/L. A control group was tested in parallel.

The analytically determined concentration of the test item in the analyzed test medium (nominal 200 mg/L) at the start and the end of the test was 85 and 81 % of the nominal value, respectiveley. Under the conditions of the test, the test item Glyoxylic acid 50 % was sufficiently stable during the test period of 48 hours. Therefore, all reported results are related to the nominal concentration of the test item Glyoxylic acid 50 % and Glyoxylic acid (concentration in brackets).

In the control and at the test concentrations up to and including the nominal concentration of 200 mg/L (100.3 mg/L), no immobilized test organisms were observed during the test period of 48 hours.

Therefore, the 48-hour NOEC and the 48-hour EC0 to Daphnia magna were determined to be at least 200 (100.3) mg/L. The 48-hour NOEC and the 48-hour EC0 might even be higher but concentrations above 200 (100.3) mg/L were not tested. The 48 -hour EC50 and the 48 -hour EC100 were clearly higher than 200 (100.3) mg/L. These values could not be quantified due to the absence of toxicity at the test concentration up to and including the nominal concentration of 200 (100.3) mg/L.

Cross-reference 6

Reason / purpose for cross-reference:

data waiving: supporting information

Reference

Endpoint:

toxicity to aquatic algae and cyanobacteria

Type of information:

experimental study

Adequacy of study:

key study

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

OECD Guideline 201 (Alga, Growth Inhibition Test)

Deviations:

no

Qualifier:

according to guideline

Guideline:

EU Method C.3 (Algal Inhibition test)

Deviations:

no

GLP compliance:

yes

Remarks:

Huntingdon Life Sciences, Wooley Road, Alconbury, Huntingdon, Cambridgeshire, PE284HS, England

Analytical monitoring:

yes

Details on sampling:

The test concentrations were not verfied as part of this study. Samples taken during the definitive test were returned to the Sponsor for analysis (see Clariant study 1114).

Vehicle:

no

Details on test solutions:

The test substance (200 mg) was added directly to sterile culture medium (2 L). This aqueous solution was either used directly at the highest test concentration or was serially diluted with sterile culture medium to provide the media at the lower test concentrations.
In addition a portion (800 mL) of the medium prepared at 100 mg/L was adjusted using sodium hydroxide (0.1 M) from pH 4.6 to 7.6 before use.

Test organisms (species):

Scenedesmus capricornutum

Details on test organisms:

TEST ORGANISM
- Common name: Selenastrum capricornutum
- Strain: No CCAP 278/4
- Source (laboratory, culture collection): Axenic, uni-cellular, liquid slope cultures of algae were obtained frmom the Culture Collection of Algae and Protozoa, Institute of Freshwater Ecology, Cumbria, UK

Test type:

static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

72 h

Test temperature:

23.5 - 24.2°

pH:

pH 7.6 at the beginning of the test and 6.9 at 72 h
As a marked pH drop (4.36 -4.71) of the algal medium (pH 7.52 -9.96) was observed after addition of the highest test substance concentration (100 mg/L), the test at 100 mg/L was also done with pH-adjustment of the test medium with NaOH (pH value remained between 7.64 and 6.90).

Nominal and measured concentrations:

nominal concentrations: 0, 4.27, 9.39, 20.7, 45.5 or 100 mg/L.

Details on test conditions:

The effect of Glyoxylic acid 50 on the growth of the unicellular green alga Selenastrum capricornutum was assessed under non-axenic conditions.


Triplicate algal cultures, with an initial cell density of 1 x 10E4/mL, were exposed to Glyoxylic acid 50 dispersed in algal nutrient medium at nominal concentration of 0, 4.27, 9.39, 20.7, 45.5 and 100 mg/L.
At 100 mg/L, the culture medium became acidic (pH 4.4 at the beginning of the test and 4.7 at 72 h) after the addition of the test substance, so algae were exposed to test medium with and without pH adjustment at 100 mg/L (pH 7.6 at the beginning of the test and 6.9 at 72 h); at 4.27 to 45.5 mg/L, no adjustment of pH was conducted.
The cultures were incubated in an orbital incubator under continuous illumination at temperatures ranging from 23.5 to 24.2°C for 72 hours.

pH of control cultures were 7.52 at the beginning of the test and 9.96 at 72 hours.

Cell numbers were counted daily to monitor growth. The test result are expressed in terms of the area under the growth curve and rowth rate using nominal exposure concentrations.

Duration:

72 h

Dose descriptor:

EC50

Effect conc.:

65.4 mg/L

Nominal / measured:

meas. (geom. mean)

Conc. based on:

test mat.

Remarks:

without pH adjustment

Basis for effect:

biomass

Duration:

72 h

Dose descriptor:

EC50

Effect conc.:

67.5 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Remarks:

without pH adjustment

Basis for effect:

biomass

Duration:

72 h

Dose descriptor:

EC50

Effect conc.:

65 mg/L

Nominal / measured:

meas. (geom. mean)

Conc. based on:

test mat.

Remarks:

without pH adjustment

Basis for effect:

growth rate

Duration:

72 h

Dose descriptor:

EC50

Effect conc.:

69.5 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Remarks:

without pH adjustment

Basis for effect:

growth rate

Duration:

72 h

Dose descriptor:

EC50

Effect conc.:

> 100 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Remarks:

with pH adjustment

Basis for effect:

biomass

Duration:

72 h

Dose descriptor:

EC50

Effect conc.:

> 100 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Remarks:

with pH adjustment

Basis for effect:

growth rate

Duration:

72 h

Dose descriptor:

NOEC

Effect conc.:

37.1 mg/L

Nominal / measured:

meas. (geom. mean)

Conc. based on:

test mat.

Basis for effect:

other: Growth curve

Details on results:

The results of the chemical analysis performed by the Sponsor confirmed that the intended exposure cocentrations were achieved, ranging between 83 to 96 % of their nominal values at the start of the algal test. After 72 hours, the concentrations measured in samples of expired media containing algal cells had decreased, ranging between 58 and 91 % of their nominal values (between 63 and 97 % of their starting values), with the greatest losses occurring where algal growth was not inhibited. Based on a geometirc mean, the overall measured concentrations were 3.05, 7.57, 17.7, 37.1 and 92.4 mg/L for media in which the pH had not been adjusted.

Since the concentrations measured at some of the exposure levels decreased by more than 20 % during the test, the results from the algal test have been re-calculated using the geometric means of the concentrations measured at the start and end of the test.

The following values were derived from the data:
Area under the growth curve
EbC50 (0-72 h) Nominal concentrations:
No pH adjustment: 67.5 (45.5 - 100) mg/L , pH adjustment at 100 mg/L: > 100 mg/L (no inhibition)

EbC50 (0-72 h) Measured concentrations:
No pH adjustment: 65.4 (42.4 - 76.9) mg/L

Average specific growth rate:
ErC50 (0-72 h) Nominal concentrations:
No pH adjustment: 69.5 (45.5 - 100) mg/L , pH adjustment at 100 mg/L: > 100 mg/L (no inhibition)

ErC50 (0-72 h) Measured concentrations
No pH adjustment: 65.0 (47.4 - 88.0) mg/L

No Observed effect concentration (NOEC)
Nominal concentrations, no pH adjustment: 45.5 mg/L
Measured concentrations, no pH adjustment: 37.1 mg/L
pH adjustment at 100 mg/L: >= 100 mg/L.

Results with reference substance (positive control):

The results of the most recent laboratory reference tets using potassium dichromate indicated that its 72-hour EbC50 to Selenastrum capricornutum was 0.86 mg/L, this was in the range typically obtained in this laboratory (0.3 to 1 mg/L).

When the pH of the algal medium was adjusted after the addition of the test substance at 100 mg/l, algal growth was not inhibited.

Validity criteria fulfilled:

yes

Executive summary:

To assess the effect of Glyoxylic Acid a toxicity study on the growth of Selenastrum capricornutum was conducted in accordance with OECD TG 201 (1984). Growth inhibition was observed over 72 hours of exposure employing nominal concentrations of 0, 4.27, 9.39, 20.7, 45.5 or 100 mg/L of Glyoxylic Acid. As a marked pH drop (4.36 -4.71) of the algal medium (pH 7.52 -9.96) was observed after addition of the highest test substance concentration (100 mg/L), the test at 100 mg/L was also done with pH-adjustment of the test medium with NaOH (pH value remained between 7.64 and 6.90). Since the concentrations measured at some of the exposure levels decreased by more than 20 % during the test without pH-adjustment, results were re-calculated using the geometric means of the concentrations measured at the start and end of the test.Without pH-adjustment of the medium the EbC50 and ErC50 were 67.5 mg/L nominal (65.4 mg/L mean measured) and 69.5 mg/L nominal (65.0 mg/L mean measured), respectively. With pH-adjustment of the medium both the EbC50 and ErC50 were >100 mg/L nominal. The NOEC for both area under the growth curve and growth rate was calculated to be 37.1 mg/L nominal (45.5 mg/L mean measured).