1,2-Benzenediol, 4-(2-hydroxyethyl)-

Toxicity to aquatic algae and cyanobacteria

Administrative data

Endpoint:

toxicity to aquatic algae and cyanobacteria

Type of information:

experimental study

Adequacy of study:

key study

Study period:

17th March 2020 to 28th April 2020

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2020

Report date:

2020

Materials and methods

Test guideline

Qualifier:

according to guideline

Guideline:

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

GLP compliance:

yes

Test material

Test material information

1

Reference substance name:

4-(2-hydroxyethyl)benzene-1,2-diol

EC Number:

600-704-3

Cas Number:

10597-60-1

Molecular formula:

C8H10O3

IUPAC Name:

4-(2-hydroxyethyl)benzene-1,2-diol

Sampling and analysis

Analytical monitoring:

yes

Details on sampling:

Analysis frequency: in 0-hour fresh solution and 72-hour old solution

Test solutions

Details on test solutions:

Method of preparation of stock solution:
Range Finding Test
A solution at 1000 mg/L of the test item was prepared in culture medium. Then 5 different concentrations were prepared, with ten-fold dilutions from 1000 mg/L to 0.01 mg/L.

Definitive Test
Method of preparation of test solutions:
After the range finding test a solution at 1000 mg/L of the test item has been prepared in culture medium. Then 5 dilutions have been performed in culture medium in order to obtain the diluted nominal solutions 1.28, 3.20, 8.0, 20.0 and 50.0 mg/L.

Test organisms

Test organisms (species):

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

Details on test organisms:

TEST ORGANISM
- Common name: Pseudokirchneriella subcapitata
- Strain: SAG 61.81
- Source: Breeder in Eurofins Biolab Test Facility
- Method of cultivation: The algal suspension in breeding in Eurofins Biolab was kept in culture medium in sterile 250 mL Erlenmeyer flasks until the beginning of the test.

Study design

Test type:

static

Water media type:

freshwater

Limit test:

yes

Total exposure duration:

72 h

Post exposure observation period:

0, 24, 48 and 72 hours

Test conditions

Nominal and measured concentrations:

Based on a preliminary test, the test concentrations were used as follows:

Nominal amount of test item A solution of 1000 mg/L was prepared in culture medium.
Then five nominal concentrations were prepared 1.28, 3.20, 8.0, 20.0 and 50.0 mg/L.

Measured concentrations: the determined concentrations in fresh media were 0.91, 1.84, 4.63, 14.02 and 49.47 mg/L. The determined concentrations in 48 hours old media were 0.00, 0.00, 0.00, 0.00 and 0.00 mg/L.

The sample is considered not stable because the measured concentration of the test item at the end of the test has not been maintained within + 20% to the concentration at the measured concentrations at the beginning of the test.

Details on test conditions:

TEST SYSTEM
- Initial cells density: 10° cell/mL
- No. of vessels per concentration (replicates): 3
- No. of vessels per control (replicates): 6

GROWTH MEDIUM
The culture medium has been prepared by mixing 4 stock solutions; dissolved in 500ml of deionised water.
Solution 1 - NH,Cl 0.5g, CaCl, 2H20 0.9g, MgCl2 6H20 0.6g, MgSO, 7 H20 0.75g, KH3PO4 0.08g
Solution 2 - FeCl 6H20 0.032g and Na2EDTA 2H20 0.05g
Solution 3 - H3BO3 0.092g, MnCl, 4H20 0.207g, ZnCl2 (1 mL of the following solution: 150 mg in 100 mL of deionized water), COCl2 6H2O (1 mL of the following solution: 75 mg in 100 mL of deionized water), CuCl2 2H2O (1 mL of the following solution: 25 mg in 50 mL of deionized water then diluting 1 mL of it in 10 mL)
Solution 4 - NaHCO, 25g

OTHER TEST CONDITIONS
- Sterile test conditions: yes
- pH: 7.68 - 8.72
- Photoperiod: continuous light

EFFECT PARAMETERS MEASURED
- Determination of cell concentrations: every 24 hours using a Burker chamber

TEST CONCENTRATIONS
- five nominal concentrations: 1.28, 3.20, 8.0, 20.0 and 50.0 mg/L.

Reference substance (positive control):

no

Results and discussion

Effect concentrations

Key result

Duration:

72 h

Dose descriptor:

EC50

Effect conc.:

6.686 mg/L

Nominal / measured:

meas. (initial)

Conc. based on:

test mat.

Basis for effect:

cell number

Details on results:

The sample is considered not stable because the measured concentration of the test item at the end of the test has not been maintained within + 20 %to the concentration at the measured concentrations at the beginning of the test.

As the test item was not stable the statistical analysis (EC50) has been performed using the measured concentrations at T=0.

A normal and healthy appearance of the algae at the end of the test was observed at microscopic for control and treated group.

Applicant's summary and conclusion

Validity criteria fulfilled:

yes

Conclusions:

The obtained results showed that Algae EC50 of the nominal concentration of the test item 'HYDROXYTYROSOL' after 72 hours is 6.686 mg/L.

Executive summary:

The growth inhibition test on a culture of algae Pseudokirchneriella subcapitata was performed with the test item 'HYDROXYTYROSOL'. The growth inhibition test on the algae Pseudokirchneriella subcapitata was performed on a culture in exponential growth phase. This approach, according to OECD 201, allowed the calculation of the growth inhibition (effect) concentration to define a limit not toxic threshold.
During the range finding test the algae were exposed to 5 different dilutions of the test item for 72 hours. Following the range finding test an EC₅₀ test was performed. The algae were exposed to 5 dilutions of the test item for 72 hours. Algae were measured using a Burker chamber. At the end of the test, a microscopic observation was performed to verify a normal and healthy appearance of the inoculum culture and to observe any abnormal appearance of the algae. At the beginning and at the end of the test (72 hours) pH was been measured in all the vessels. Ambient temperature was recorded daily.
Stability of the test item in the definitive test was performed using HPLC equipped with UV detector according to method described in STULV20AA0627-1 GLP - MdP.
The test item was measured at the beginning and at the end of the test in the control and in the treated samples.
The results, in compliance with test acceptability criteria, can be summarised as follows:
EC₅₀ (72 h) of the test item 'HYDROXYTYROSOL' (measured concentration at the beginning of the test): 6.686 mg/L