Glutamic acid

Toxicity to aquatic algae and cyanobacteria

Administrative data

Endpoint:

toxicity to aquatic algae and cyanobacteria

Type of information:

other: SIDS

Adequacy of study:

other information

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

data from handbook or collection of data

Data source

Reference

Reference 1

Reference Type:

publication

Title:

SIDS for L-Glutamic acid

Author:

OECD

Year:

2013

Report date:

2013

Reference 2

Reference Type:

study report

Title:

Unnamed

Year:

2009

Materials and methods

Test guideline

Qualifier:

according to guideline

Guideline:

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

GLP compliance:

yes (incl. QA statement)

Test material

Specific details on test material used for the study:

- Name of test material: L-glutamic acid
- Molecular formula: C5H9NO4
- Molecular weight: 147.13
- Substance type: White Powder
- purity: 99.5%
- Lot No.: 1371820
- Supplier: SIGMA-ALDRICH Inc.
- Storage condition of test material: Room temperature (15.9~27.1℃)

Sampling and analysis

Analytical monitoring:

yes

Test solutions

Details on test solutions:

- Culture Medium: The culture medium, which is recommended in the OECD Guideline for freshwater algal medium.
- Preparation of test solutions: The request amounts (active ingredient: 0.992) of the test substance were measured using an electronic balance. For preparation of stock and test solutions, the required amounts of the test substance were added to flask filled with culture medium. And then, stock and test solutions were prepared using a stirrer. For the range finding study, a stock solution of 100 mg/L of the test substance was prepared using culture medium. This stock solution was diluted to concentrations of 10, 1 and 0.1 mg/L of the test substance with culture medium. One hundred mg/L of the test substance was prepared for the definitive study. This solution was diluted with culture medium to yield concentrations of 31, 10, 3 and 1 mg/L of the test substance. One hundred mL of each test solution and 100 mL of culture medium (control) were placed in test flasks. The test solution was prepared prior to dosing.

Test organisms

Test organisms (species):

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

Details on test organisms:

- Lot No.: 7403439
- Source: American Type Culture Collection (ATCC. U.S.A.)

Study design

Test type:

static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

72 h

Test conditions

Test temperature:

22.5~23.0℃

pH:

- 0h: 5.4~7.6
- 72h: 5.0~7.4

Nominal and measured concentrations:

- test concentration: 1, 3, 10, 31 and 100 mg/L (nominal concentrations)

Details on test conditions:

- Test concentrations: As a result of the range finding study, the inhibition of algal growth rate was 52.9% at 100 mg/L, while the inhibition of algal growth was not observed at 1 mg/L (inhibition of algal growth rate: 2.45%). Therefore, the highest concentration in the definitive study was selected as 100 mg/L and set by a geometric ratio of 3.2 additional 4 lower concentration levels including 31, 10, 3 and 1 mg/L. The control group was established.
- Test procedure and exposure conditions: Pre-culture, algal suspensions were added to replicate flasks containing the test substance solutions and adjusted to an algal biomass concentration of 1x10^4 cells/mL. Flasks were incubated at 23+/-2℃ under continuous illumination (4440-8880 Lux) and constantly shaken at approximately 100 rpm using a shaker incubator for a period of 72 hours. Flasks were rotated upward and to the left at 24 hours intervals during incubation in an attempt to equally distribute light intensity. Six replicate flasks were prepared for each dosed group and control group.

Results and discussion

Effect concentrations

Effect concentrations 1

Key result

Duration:

72 h

Dose descriptor:

EC50

Effect conc.:

68.5 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

growth rate

Remarks on result:

other: 95% CL: 62.4-74.1 mg/L

Effect concentrations 2

Key result

Duration:

72 h

Dose descriptor:

EC50

Effect conc.:

54.4 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

biomass

Remarks on result:

other: 95% CL: 50.0~59.4mg/L

Effect concentrations 3

Duration:

72 h

Dose descriptor:

NOEC

Effect conc.:

31 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Details on results:

All test and control cultures were inspected microscopically at 72 hours. No abnormalities were detected in any of the cultures and there was no sign of contamination by foreign algal cells or protozoa.

Reported statistics and error estimates:

- Calculation of Median Effect Concentration (EC50): At 72 hours after initiation of exposure, the percent inhibition of growth in the dosed group and control group was calculated and a concentration-percent inhibition growth curve generated. The ErC50 (0-72 hours) and EyC50 (0-72 hours) were calculated and their 95% confidence limits were statistically analyzed using the Logit method. Statistical analysis was conducted using SAS (version 9.1.3, SAS Institute Inc., Cary, NC, U.S.A.)
- Determination of No Observed Effect Concentration (NOEC) and Lowest Observed Effect Concentration
(LOEC): In the case of the multiple comparisons for the determination of the NOEC and LOEC for average specific growth rate and yield, Bartlett's test was conducted to test for homogeneity. One-way analysis of variance (ANOVA) was employed on homogeneous data. And then, if significant, followed by Dunnett's t-test for multiple comparisons. A Kruskal-Wallis test was employed on heterogeneous data and if significant, followed by Steel test for multiple comparisons. Statistical analysis was conducted using SAS (version 9.1.3, SAS Institute Inc., Cary, NC, U.S.A.)

Applicant's summary and conclusion

Validity criteria fulfilled:

not specified

Conclusions:

The 72 h-EC50 values of L-glutamic acid to Pseudokirchneriella subcapitata was determined as 68.5 mg/L (nominal) for average growth rate and 54.4 mg/L for yield.

Executive summary:

This study was designed to assess the effect of the test substance, L-glutamic acid (CAS No.: 56-86-0), on the growth of the fresh water alga, Pseudokirchneriella subcapitata, during a 72 hour exposure period under static test conditions. It was determined the EC50 (median effect concentration) for percentile inhibition in average specific growth rate and yield in each group. The nominal concentration was selected as 100, 31, 10, 3 and 1 mg/L. The control group was prepared for this study. The concentration of the test substance during the exposure period was within +/-20% of the nominal concentrations. Therefore, all test results were determined as the nominal concentrations. In the control group, the concentration of the test substance was not detected.