2-naphthol

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:

24.01.2018 - 21.03.2018

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

OECD Guideline 301 A (Ready Biodegradability: DOC Die Away Test)

Deviations:

no

GLP compliance:

no

Remarks:

accredited by DAkkS

Oxygen conditions:

aerobic

Inoculum or test system:

activated sludge, industrial, non-adapted

Duration of test (contact time):

28 d

Key result

Parameter:

% degradation (DOC removal)

Value:

81

Sampling time:

28 d

Table 1: DOC-content of blank value-samples and samples with 2 -naphthol, calculated mean values and resulting difference as well as DOC-degradation within total test duration.

test duration [d]	DOC [mg/l] of ß-Naphthol-samples			DOC [mg/l] of blank value samples			DOC-difference [mg/l]	DOC degradation[%]
	I	II	mean	I	II	mean
0	60,59	58,90	59,75	9,40	8,99	9,20	50,55	0
2	42,66	44,12	43,39	1,80	2,82	2,31	41,08	19
5	46,73	46,60	46,67	4,49	3,97	4,23	42,44	16
7	50,30	47,96	49,13	4,92	6,13	5,53	43,61	14
9	47,60	43,59	45,60	5,74	5,44	5,59	40,01	21
12	37,33	29,19	33,26	7,25	9,27	8,26	25,00	51
14	16,14	14,55	15,35	5,72	4,42	5,07	10,28	80
16	7,56	9,27	8,42	< 0,5	< 0,5	< 0,5	7,92	84
19	13,13	10,99	12,06	< 0,5	4,96	2,48	9,33	82
23	12,28	10,74	11,51	0,50	5,57	3,04	8,48	83
28	12,54	10,27	11,41	2,34	1,54	1,94	9,47	81

       

Validity criteria fulfilled:

yes

Remarks:

The reference samples biodegraded within 5 days to a degree of 85%. Abiotic control samples showed only low DOC-degradation of 41 mg/l and 32 mg/l.

Interpretation of results:

readily biodegradable

Conclusions:

2-Naphthol is rapidly biodegradable as deteminend by a OECD 301A: DOC Die-Away-Test.

Executive summary:

As a criterion for the classification as rapidly biodegradable a DOC-elimination of 70% of the test item within a 10 day-window during a total test duration of 28 days is considered. The test samples of bata-naphthol does meet this criterion since a DOC-elimination of 70% in the 10 day-window is exceeded. Hence, 2 -naphthol is classified as rapidly biodegradable.

Description of key information

The ready biodegradability of the test substance 2-naphthol was evaluated in accordance with the OECD Testing Guideline 301 A (Ready Biodegradability: DOC Die Away Test).

Sodium acetate trihydrate was used as a reference substance.

The test was performed in duplicate with a known concentration of test substance in inoculated medium incubated at a constant temperature in the dark over 28 days.  Sampling was performed at day 0, 2, 5, 7, 9, 12, 14, 16, 19, 23 and 28 days.

The determination of the DOC value was performed using a DOC measurement device (company: DIMATOC) by triple measurement.

The % degradation (DOC removal) after 28 days was 81%.  The criterion for classification as rapidly biodegradable is a DOC-elimination of 70% of the test item within a 10 day-window during a total test duration of 28 days. Hence, the test substance 2-Naphthol meets the criteria to be classified as readily biodegradable.

The validity criteria was met as the reference samples biodegraded within 5 days to a degree of 85%.  Abiotic control samples showed only low DOC-degradation of 41 mg/L and3 2 mg/L.

Key value for chemical safety assessment

Biodegradation in water:

readily biodegradable

Type of water:

other: A solution on mineral salts without a carbon source