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

Biodegradation in water: screening tests

Administrative data

Endpoint:

biodegradation in water: ready biodegradability

Type of information:

experimental study

Adequacy of study:

key study

Study period:

19th March 2020 to 27th 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 301 B (Ready Biodegradability: CO2 Evolution 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

Study design

Oxygen conditions:

aerobic

Inoculum or test system:

activated sludge (adaptation not specified)

Details on inoculum:

- Source of inoculum/activated sludge: mixed treatment plant of urban (about 66%) and industrial (about 34%)liquid sewage situated at San Rocco Monza (MB), Italia.
- Storage conditions: the sampled muds were mixed and let settle and kept in aerobic conditions for 3 days.
- Preparation of inoculum for exposure: The mud samples, before their use, were analysed to check the ability to form colony units. Then it was centrifuged, washed and analysed to quantify the suspended solids concentration for the inoculum preparation.

- Concentration of sludge: The inoculum was prepared in order to have a concentration of suspended solid of about 4 mg/L.

Duration of test (contact time):

28 d

Initial test substance concentration

Initial conc.:

2.199 mg/L

Based on:

IC (inorganic carbon)

Parameter followed for biodegradation estimation

Parameter followed for biodegradation estimation:

inorg. C analysis

Details on study design:

TEST CONDITIONS
- Composition of medium:
Stock Solution A: 8.5g/l of KH2PO4, 21.75g/l of K2HPO4, 33.40g/l of Na2HPO4.2H2O and 0.5g/l NH4Cl
Stock Solution B: 36.40g/l CaCl2 . 2H2O
Stock Solution C: 22.50g/L MgSO4 . 7H2O
Stock Solution D: 0.25g/l FeCl3 . 6H2O
To prepare 1L of mineral medium, 10ml of Stock Solution A was added to 800ml of distilled water, stirred and 1ml each of Stock Solutions B, C and D added. The mixture was then made up to 1L with distilled water.
- Test temperature: 20 ± 1 oC
- pH: 7.48
- Suspended solids concentration: 4 mg/L
Light: Incubation carried out in the dark

TEST SYSTEM
- Culturing apparatus: 1L flasks
- Number of culture flasks/concentration: 23 (blank, test sample, reference substance) 8 (test sample + reference substance, abiotic check)

SAMPLING
- Sampling frequency: 3 replica / once a week and 5 replica at day 28

CONTROL AND BLANK SYSTEM
- Inoculum blank: Blank prepared containing water, culture medium and the inoculum of mud.
- Abiotic check: Test item with 50 mg/L HgCl2 in order to check for possible abiotic degradation..
- Toxicity control: Considering Sodium benzoate as reference substance using its molecular formula, a starting nominal concentration of 20.05 mg/L of organic carbon (TOC) has been used.
- Test sample + Reference substance: Test sample and reference substance in order to have a final concentration given by the sum of organic carbon (TOC) of the 2 substances.

Reference substance

Reference substance:

benzoic acid, sodium salt

Results and discussion

% Degradation

Key result

Parameter:

% degradation (inorg. C analysis)

Value:

61

Sampling time:

28 d

Details on results:

The mean amount of TIC present in the blank controls at the end of the test is < 3 mg C/L.
The solutions in the bottles containing the test item changed color from transparent to slightly orange during the test.
Abiotic degradation has occurred because the amount of TIC during the test in the abiotic bottles is greater than 10% so has been considered in the final percentage of biodegradation.

% of abiotic biodegradation at 28 days: 9%

Reference substance + test item confirms the absence of an inhibitory effect of the test sample on inoculum at the concentration at which it was applied in the test (4.62%).

BOD5 / COD results

Results with reference substance:

% BIODEGRADATION - 65%

Applicant's summary and conclusion

Validity criteria fulfilled:

yes

Interpretation of results:

readily biodegradable

Conclusions:

On the basis of results obtained, interpreted in accordance to OECD 310:2014, the test item 'HYDROXYTYROSOL’ is considered readily biodegradable in aerobic conditions.
% of total aerobic biodegradation at 28 days: 61%
% of abiotic biodegradation at 28 days: 9%

Executive summary:

The analysis of inorganic carbon for the evaluation in an aqueous medium of the aerobic biodegradability of the test item, “HYDROXYTYROSOL”, has been performed following screening method described in OECD 310: 2014. For this purpose the amount of developed inorganic carbon has been measured and reported in comparison to a blank.
The test has been done using the test item with a fixed concentration of organic carbon (see Par. Assay Execution). Samples have been kept at the temperature of 20 ± 1 °C for the whole period of the test (28 days).
On the basis of results obtained, interpreted in accordance to OECD 310:2014, the test item 'HYDROXYTYROSOL’ is considered readily biodegradable in aerobic conditions.
% of total aerobic biodegradation at 28 days: 61%
% of abiotic biodegradation at 28 days: 9%