4-methyl-salicylamide

Biodegradation in water: screening tests

Administrative data

Endpoint:

biodegradation in water: ready biodegradability

Type of information:

experimental study

Adequacy of study:

key study

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: According to official guidelines and GLP

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2016

Materials and methods

Test guideline

Test guideline 1

Qualifier:

according to guideline

Guideline:

OECD Guideline 301 B (Ready Biodegradability: CO2 Evolution Test)

Test guideline 2

Qualifier:

according to guideline

Guideline:

EU Method C.4-C (Determination of the "Ready" Biodegradability - Carbon Dioxide Evolution Test)

Test guideline 3

Qualifier:

according to guideline

Guideline:

ISO DIS 9439 (Ultimate Aerobic Biodegradability - Method by Analysis of Released Carbon Dioxide)

Test guideline 4

Qualifier:

according to guideline

Guideline:

other: ISO International Standard 10634 "Water Quality - Guidance for the preparation and treatment of poorly water-soluble organic compounds for the subsequent evaluation of their biodegradability in an aqueous medium" (1995).

GLP compliance:

yes (incl. QA statement)

Test material

Reference

Name:

Unnamed

Type:

Constituent

Type:

Constituent

Test material form:

solid: crystalline

Details on test material:

Identification: V250208
Appearance: Off-white crystals
Batch: F8A
Purity/Composition: >96 %
<3 % 4-methylsalicylacid
<1 % 4-methylsalicylacid-methylester
<0.5 % water
Test item storage: At room temperature protected from light
Stable under storage conditions until: 03 September 2016 (expiry date)
Molecular formula: C8H9NO2
Molecular weight: 151.16

Study design

Oxygen conditions:

aerobic

Inoculum or test system:

sewage, predominantly domestic (adaptation not specified)

Details on inoculum:

The source of test organisms was activated sludge freshly obtained from a municipal sewage treatment plant: 'Waterschap Aa en Maas', 's-Hertogenbosch, The Netherlands, receiving predominantly domestic sewage.
The freshly obtained sludge was kept under continuous aeration until further treatment. The concentration of suspended solids was determined to be 3.8 g/L in the concentrated sludge. Before use, the sludge was allowed to settle (33 minutes) and the supernatant liquid was used as inoculum at the amount of 10 mL/L of mineral medium.

Duration of test (contact time):

28 d

Initial test substance concentration

Initial conc.:

2.33 mg/L

Based on:

other: ThCO2

Parameter followed for biodegradation estimation

Parameter followed for biodegradation estimation:

CO2 evolution

Details on study design:

The day before the start of the test (day -1) mineral components, Milli-RO water (ca. 80% of final volume) and inoculum (1% of final volume) were added to each bottle. This mixture was aerated with synthetic air overnight to purge the system of CO2.

Test suspension: containing test item and inoculum (2 bottles).
Inoculum blank: containing only inoculum (2 bottles) Positive control: containing reference item and inoculum (1 bottle).
Toxicity control: containing test item, reference item and inoculum (1 bottle).

At the start of the test (day 0), test and reference item were added to the bottles containing the microbial organisms and mineral components.
The volumes of suspensions were made up to 2 litres with Milli-RO water, resulting in the mineral medium described before.
Three CO2-absorbers (bottles filled with 100 mL 0.0125 M Ba(OH)2) were connected in series to the exit air line of each test bottle.

Reference substance

Reference substance:

acetic acid, sodium salt

Results and discussion

Test performance:

The relative biodegradation values calculated from the measurements performed during the test period revealed 22% and 6% biodegradation of V250208 (based on ThCO2), for the duplicate bottles tested. Thus, the criterion for ready biodegradability (at least 60% biodegradation within a 10-day window) was not met. In the toxicity control, more than 25% biodegradation occurred within 14 days (33%, based on ThCO2). Therefore, the test item was assumed not to inhibit microbial activity.

% Degradation

% Degradation 1

Parameter:

% degradation (CO2 evolution)

Value:

22

Sampling time:

28 d

% Degradation 2

Parameter:

% degradation (CO2 evolution)

Value:

6

Sampling time:

28 d

BOD5 / COD results

Results with reference substance:

Functioning of the test system was checked by testing the reference item sodium acetate, which showed a normal biodegradation curve.

Applicant's summary and conclusion

Validity criteria fulfilled:

yes

Interpretation of results:

other: The criterion for ready biodegradation was not met

Conclusions:

The relative biodegradation values calculated from the measurements performed during the test period revealed 22% and 6% biodegradation of V250208 (based on ThCO2), for the duplicate bottles tested. Thus, the criterion for ready biodegradability (at least 60% biodegradation within a 10-day window) was not met.