Naphthalenesulfonic acid, di-C9-rich C8-10-branched alkyl derivs., calcium salts

Biodegradation in water: screening tests

Link to relevant study record(s)

Reference

Endpoint:

biodegradation in water: ready biodegradability

Type of information:

experimental study

Adequacy of study:

key study

Study period:

March 6, 2012 to May 22, 2012

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

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

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Oxygen conditions:

aerobic

Inoculum or test system:

activated sludge, 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.

Duration of test (contact time):

>= 28 d

Initial conc.:

>= 19.5 mg/L

Based on:

ThIC

Parameter followed for biodegradation estimation:

CO2 evolution

Details on study design:

The study consisted of six bottles:
- 2 inoculum blanks (no test substance),
- 2 test bottles (di C8-C10, branched, C9 rich, alkylnaphthalene sulphonic acid (DNNSA)),
- 1 positive control (sodium acetate) and
- 1 toxicity control (di C8-C10, branched, C9 rich, alkylnaphthalene sulphonic acid (DNNSA) plus sodium acetate).

Preliminary study:

No preliminary test was conducted.

Test performance:

1. The positive control substance was biodegraded by at least 60% (73%) within 14 days.
2. The difference of duplicate values for %-degradation of the test substance was always less than 20.
3. The total CO2 release in the blank at the end of the test did not exceed 40 mg/l (46 mg CO2 per 2 litres of medium, corresponding to 23 mg CO2/l).
4. The Inorganic Carbon content (IC) of the test substance (suspension) in the mineral medium at the beginning of the test was less than 5% of the Total Carbon content (TC). Since the test medium was prepared in tap-water purified by reverse osmosis (Milli-RO water (Millipore Corp., Bedford, Mass., USA, carbon levels < 500 ppb)), IC was less than 5% of TC (mainly coming from the test substance, 13 mg TOC/l).

Since all criteria for acceptability of the test were met, this study was considered to be valid.

Key result

Parameter:

% degradation (CO2 evolution)

Value:

14

Sampling time:

29 d

Details on results:

See results table

Results with reference substance:

The relative biodegradation values calculated from the measurements performed during the test period revealed 14 and 17% biodegradation of di C8-C10, branched, C9 rich, alkylnaphthalene sulphonic acid (DNNSA), 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 substance was assumed not to inhibit microbial activity.

Table 1    CO2 production and percentage biodegradation of the test substance (bottle A).
	Day	HCl (0.05 N) titrated (ml)		Produced CO2 (ml HCl)	Produced CO2 (mg)	Cumulative CO2 (mg)	Biodegradation^1) (%)
		Blank (mean)	bottle A
	2	47.89	47.09	0.79	0.9	0.9	1
	5	47.04	45.71	1.33	1.5	2.3	3
	7	47.15	45.91	1.24	1.4	3.7	4
	9	46.78	45.83	0.95	1.0	4.7	5
	14	46.06	45.29	0.77	0.8	5.6	6
	19	44.81	43.71	1.10	1.2	6.8	8
	23	44.98	43.41	1.57	1.7	8.5	10
	27	45.32	44.23	0.00	0.0	8.5	10
	29	45.93	44.93	1.00	1.1	9.6	11
	29	48.63	47.12	1.51	1.7	11.3	13
	29	49.53	48.46	1.07	1.2	12.5	14
	^1): Calculated as the ratio between CO2produced (cumulative) and the ThCO2of the test substance: 87.3 mg CO2/2l

 

 

Table 2    CO2 production and percentage biodegradation of the test substance (bottle B).
	Day	HCl (0.05 N) titrated (ml)		Produced CO2 (ml HCl)	Produced CO2 (mg)	Cumulative CO2 (mg)	Biodegradation^1) (%)
		Blank (mean)	bottle B
	2	47.89	47.49	0.39	0.4	0.4	0
	5	47.04	46.21	0.82	0.9	1.3	2
	7	47.15	45.75	1.40	1.5	2.9	3
	9	46.78	46.10	0.68	0.7	3.6	4
	14	46.06	44.78	1.28	1.4	5.0	6
	19	44.81	43.15	1.66	1.8	6.9	8
	23	44.98	43.35	1.63	1.8	8.6	10
	27	45.32	43.11	2.21	2.4	11.1	13
	29	45.93	44.60	1.33	1.5	12.5	14
	29	48.63	46.86	1.77	1.9	14.5	16
	29	49.53	48.76	0.77	0.8	15.3	17
	^1): Calculated as the ratio between CO2produced (cumulative) and the ThCO2of the test substance:88.2 mg CO2/2l

Validity criteria fulfilled:

yes

Interpretation of results:

other: not readily biodegradable

Conclusions:

Under the conditions of the test, di C8-C10, branched, C9 rich, alkylnaphthalene sulphonic acid (DNNSA) was not readily biodegradable.

Executive summary:

DNNSA is the main component of CALCIUM BIS( DI C8-C10, BRANCHED, C9 RICH, ALKYLNAPHTHALENE SULPHONATE). Testing with DNNSA can used as read-across for its calcium salt.

A ‘ready’ biodegradability (modified Sturm test) was conducted with di C8-C10, branched, C9 rich, alkylnaphthalene sulphonic acid (DNNSA). The study procedures described in this report were based on the OECD guideline No. 301 B, 1992. In addition, the procedures were designed to meet the test methods of the Commission Regulation (EC) No. 440/2008 of 30 May 2008, Publication No.L142, Part C.4-C and the ISO International Standard 9439, 1999 and ISO Standard 10634, 1995.

 

di C8-C10, branched, C9 rich, alkylnaphthalene sulphonic acid (DNNSA) was a brown highly viscous liquid with a purity of provisional 84%. The test substance was tested in duplicate at 19.5 mg/l, corresponding to 13 mg TOC/l. The organic carbon content was based on the molecular formula and the purity of the testsubstance. The Theoretical CO₂production (ThCO₂) of di C8-C10, branched, C9 rich, alkylnaphthalene sulphonic acid (DNNSA) was calculated to be 2.49 mg CO₂/mg.

 

The study consisted of six bottles:

-         2 inoculum blanks (no test substance),

-         2 test bottles (di C8-C10, branched, C9 rich, alkylnaphthalene sulphonic acid (DNNSA)),

-         1 positive control (sodium acetate) and

-         1 toxicity control (di C8-C10, branched, C9 rich, alkylnaphthalene sulphonic acid (DNNSA) plus sodium acetate).

 

Since di C8-C10, branched, C9 rich, alkylnaphthalene sulphonic acid (DNNSA) was not sufficiently soluble to allow preparation of an aqueous solution at a concentration of 1 g/l, weighed amounts were added to the 2-litres test bottles containing medium with microbial organisms and mineral components. The test solutions were continuously stirred during the test, to ensure optimal contact between the test substance and the test organisms. Test duration was 28 days (last CO₂-measurement on the 29^thday).

 

The relative biodegradation values calculated from the measurements performed during the test period revealed 14 and 17% biodegradation of di C8-C10, branched, C9 rich, alkylnaphthalene sulphonic acid (DNNSA), 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, di C8-C10, branched, C9 rich, alkylnaphthalene sulphonic acid (DNNSA) was found not to inhibit microbial activity. Since all criteria for acceptability of the test were met, this study was considered to be valid.

 

In conclusion, di C8-C10, branched, C9 rich, alkylnaphthalene sulphonic acid (DNNSA) was designated as not readily biodegradable. CALCIUM BIS( DI C8-C10, BRANCHED, C9 RICH, ALKYLNAPHTHALENE SULPHONATE) is also not readily biodegradable.

Description of key information

DNNSA is an intermediate in the production process of CALCIUM BIS( DI C8-C10, BRANCHED, C9 RICH, ALKYLNAPHTHALENE SULPHONATE). Testing with DNNSA demonstrated the substance is not readily biodegradable. CALCIUM BIS( DI C8-C10, BRANCHED, C9 RICH, ALKYLNAPHTHALENE SULPHONATE) is therefore also not readily biodegradable.

Key value for chemical safety assessment

Biodegradation in water:

under test conditions no biodegradation observed

Type of water:

freshwater