Ichthyolic acid, sodium salt

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:

start of study: 22 June 1993
termination of study: 20 July 1993

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

1993

Report date:

2004

Materials and methods

Test guideline

Qualifier:

according to guideline

Guideline:

EU Method C.4-E (Determination of the "Ready" Biodegradability - Closed Bottle Test)

Version / remarks:

The study was carried out according to the EEC guideline C.4-E published in the Official Journal of the European Communities L 383 A dated December 29th, 1992

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Test material

Test material information

Constituent 1

Reference substance name:

Ichthyolic acid, sodium salt

EC Number:

215-671-7

EC Name:

Ichthyolic acid, sodium salt

Cas Number:

1340-06-3

IUPAC Name:

Identification of the UVCB substance by "Chemcial Abstracts Index Name", among others: Ichthyolic Acid, Sodium Salt. No IUPAC name known.

Test material form:

liquid

Specific details on test material used for the study:

The test substance Ichthyolic Acid, Sodium Salt was used in the form of trademark substance ICHTHYOL PALE. It originated from a regular production batch of the registrant's manufacturing site (batch R 92/0541). In the study report reference to the test substance is made with the common general descriptive term "sulfonated shale oil, pale".

Study design

Oxygen conditions:

aerobic

Inoculum or test system:

sewage, predominantly domestic, adapted

Remarks:

pre-conditioned to the experimental conditions

Details on inoculum:

Secondary effluent from a treatment plant
Inoculation was made using a secondary effluent of good quality collected from a treatment plant dealing with predominantly domestic sewage. The effluent was kept under aerobic conditions in the period between sampling and application. To perpare the inoculum the sample was filtered through a coarse filter, the first 200 ml being discarded. The rest of the filtrate was kept aerobic until use. The inoculum was used on the day of collection. The number of bacteria was determined with Easicult TTC. There were approximatley 10^6 bacteria per litre of final volume of the test medium.

Duration of test (contact time):

>= 3 - <= 28 d

Initial test substance concentration

Initial conc.:

2 mg/L

Based on:

test mat.

Parameter followed for biodegradation estimation

Parameter followed for biodegradation estimation:

O2 consumption

Details on study design:

The purpose of this test was the measurement of the biodegradability of sulfonated shale oil, pale in an aerobic, aqueous medium at a concentration of 2 mg test substance/l.
A predetermined amount of the compound is dissolved in an inorganic medium (mineral medium), providing a usual concentration of 2 mg active substance per litre (AS/l). The solution is inoculated with a small number of micro-organisms from a mixed population and kept in closed bottels in the dark in a constant temperature bath at 20°C +- 1°C. The degradation is followed by oxygen analyses over a 28-day period. A control with inoculum, but without test material, is run parallel for the determination of oxygen blanks. The procedure is checked by means of an inoculum control substance.

Reagents:
Dilution water: Distilled and desalinated water containing not more than 0.01 mg Cu/l.
Mineral Medium:
Solution 1: 0.850 g KH2PO4, 2.850 g K2HPO4.3H2O, 3.340 g Na2HPO4.2H2O, 0.050 g of NH4Cl were dissolved in distilled water and made up to 100 ml.
Solution 2: 2.25 g MgSO4.7H2O were dissolved in distilled water and made up to 100 ml.
Solution 3: 3.64 g CaCl2.2H2O were dissolved in distilled water and made up to 100 ml.
Solution 4: 0.025 g FeCl36H2O were dissolved in distilled water and made up to 100 ml.
40 ml of each solution 1 to 4 was added to aerated distilled water to give a total volume of 40.0 l mineral medium. The pH was 7.28.
24 hours before use the mineral medium was vigourously air saturated, at room temperature (20.2°C), for 20 minutes with compressed air. After standing for 24 hours the oxygen concentration at 20.3°C was 8.69 mg O2/l. All transfer and filling operations of the air saturated water were conducted bubble-free by siphon.

Inoculation was made as described under the heading "Details on inoculum".

Procedure
Test System
Test substance: sulfonated shale oil, pale (ICHTHYOL PALE)
Concentration: 2 mg/l
Control substance: sodium acetate
Concentration: 2 mg/l
Vehicle for the test and control substance: test medium
Oxygen measuring instrument: OXI DIGI 530 (WTW, Weilheim) with a Tri Oxmatic - EO 200 oxygen electrode
Duration of test 28 days

Parallel groups of BOD bottles (BOD: biochemical oxygen demand) were prepared for the determination of the test and reference chemicals in simultaneous experimental series, including inoculum blanks.
The test was conducted in duplicate in a parallel series.
Fully aerated mineral medium was added to large bottles so that they were about one-third full. Then sufficent amounts of the stock solutions of the test chemical and reference chemical were added to separate large bottles so that the final concentration of the chemicals was 2 mg/litre. No chemicals were added to the blank control medium contained in a further large bottle.
As the toxicity of the test chemical was unknown, the toxicity was investigated in another series of bottles employing the above time schedule. Each bottle contained aerated mineral medium (to about one-third of its volume) plus test chemical and reference chemicals at final concentrations 2 mg/l.
The solutions were inoculated from a pointed pipette with 308 microliter secondary effluent per litre test medium. the solutions were made up to volume with aerated mineral medium using a hose which reaches down to the bottom of the bottle to achieve adequate mixing.
Subsequently each prepared solution was dispensed in to the respective group of BOD bottles (300 ml) by hose from the lower quarter (not the bottom) of the appropriate large bottle so that all the BOD bottles were completely filled.
The bottles were gently tapped to remove any air bubbles. Two bottles were immediately analysed for dissolved oxygen. The remaining replicate bottles were stoppered ensuring that no air bubbles were enclosed and placed in a water bath at 20°C, kept in the dark and removed in duplicate after 3, 7, 10, 14, 17, 21, 24 and 28 days for immediate dissolved oxygen analysis.

Inhibition test
2 mg/l of the control compound (sodium acetate) plus 2mg/l of the test material. If the BOD values correspond to the sum of those of sodim acetate and the test substance alone, the test material does not display inhibitory effects.

Reference substance

Reference substance:

acetic acid, sodium salt

Results and discussion

Preliminary study:

no preliminary study (see "details on study design")

Test performance:

No unusual observations or occurences affecting results (see "details on study design")

% Degradation

Parameter:

% degradation (O2 consumption)

Value:

5.2

Sampling time:

28 d

Details on results:

The purpose of the study was the measurement of the biodegradability of sulfonated shale oil, pale (ICHTHYOL PALE as a trademark of Ichthyolic Acid, Sodium Salt) in an aerobic, aqueous medium at a concentration of 2 mg test substance/l. BOD and subsequently %degradation were determined according to provisions of the guideline.

Test system:
Analysis (oxygen electrode): OXI DIGI 530 with a Tri Oxmatic - EO 200 oxygen electrode
ThOD of test substance: 1.02 mg O2/mg test substance
ThOD of sodium acetate: 0.78 mg O2/mg sodium acetate
Temperature of the dilution water after aeration: 20.3°C
O2-concentration of the water (after aeration and standing before start of the test): 8.69 mg O2/l
Temperature of water bath: 19.4°C - 20.1°C

Validation of results
As required by the guideline the dissolved oxygen depletion of the blank did not exceed 1.5 mg dissolved oxygen/l after 28 days.

Inhibition test (see "details on study design")
Series 1:
control chemical: sodium acetate
Result: dissolved oxygen depletion: 1.55 mg O2/l on day 28
Series 2:
Test material: ICHTHYOL PALE
Result: dissolved oxygen depletion: 0.11 mg O2/l on day 28
Series 3:
Control chemical plus test substance:
Result: dissolved oxygen depletion: 1.66 mg O2/l on day 28
Hence, there is no difference in the results between series 3 and the sum of series 1 and 2: no inhibitory effect was observed for the test material.

Test substance:
control chemical: sodium acetate
Result: %degradation after 28 d: 99.1%
Test substance: ICHTHYOL PALE
Result: %degradation after 28 d: 5.2%

Under the present test conditions only a marginal degradation was determined for Ichthyolic Acid, Sodium Salt (ICHTHYOL PALE).

Applicant's summary and conclusion

Validity criteria fulfilled:

yes

Interpretation of results:

not readily biodegradable

Conclusions:

The purpose of the closed bottle test was the measurement of the biodegradability of Ichthyolic Acid, Sodium Salt (ICHTHYOL PALE) in an aerobic, aqueous medium at a concentration of 2 mg test substance/l. Under the test conditions only a marginal degradation was determined for the test substance.