p,p'-(2-pyridylmethylene)bisphenol

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:

2003-01-13 to 2003-04-03

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: The study was conducted under GLP conditions in accordance with the official OECD guideline No 301 F (1992)

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2003

Report date:

2003

Materials and methods

Test guideline

Test guideline 1

Qualifier:

according to guideline

Guideline:

OECD Guideline 301 F (Ready Biodegradability: Manometric Respirometry Test)

Version / remarks:

(1992)

Deviations:

no

Test guideline 2

Qualifier:

according to guideline

Guideline:

EU Method C.4-D (Determination of the "Ready" Biodegradability - Manometric Respirometry Test)

Version / remarks:

(1992)

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Remarks:

846867

Test material

Test material information

1

Reference substance name:

p,p'-(2-pyridylmethylene)bisphenol

EC Number:

210-039-7

EC Name:

p,p'-(2-pyridylmethylene)bisphenol

Cas Number:

603-41-8

Molecular formula:

C18H15NO2

IUPAC Name:

4-[(4-hydroxyphenyl)(pyridin-2-yl)methyl]phenol

Test material form:

solid

Study design

Oxygen conditions:

aerobic

Inoculum or test system:

activated sludge, domestic, non-adapted

Details on inoculum:

- Source of inoculum/activated sludge (e.g. location, sampling depth, contamination history, procedure): supplied by wastewater treatment plant ARA Ergolz II, Füllinsdorf, Switzerland- The sludge was washed twice with tap water by centrifugation and the supernatant liquid phase was decanted. A homogenized aliquot of the final sludge suspension was weighed, thereafter dried and the ratio of wet to dry weight was calculated. Based on this ratio, calculated amounts of wet sludge were suspended in test water to obtain a concentration equivalent to 4 g (+-10%) dry material per liter. During holding, the sludge was aerated at room temperature until use. Prior to use, the sludge was diluted with test water to a concentration of 1 g per liter (dry weight basis). This diluted activated sludge was used as inoculum to give a final concentration of 30 mg dry material per liter.

Duration of test (contact time):

28 d

Initial test substance concentration

Initial conc.:

100 mg/L

Based on:

test mat.

Parameter followed for biodegradation estimation

Parameter followed for biodegradation estimation:

O2 consumption

Details on study design:

TEST CONDITIONS- Composition of medium: The test water was prepared according to testing guideline. Grade salts were added to deionised water to give stock solution. Stock solutions were diluted in deionised water. In order to avoid having to prepare solution FeCl3 x 6H2O 0.25 g/L immediately before use, one drop of concentrated HCl per liter was added.- Test temperature: none given - pH: 7.3-7.7- pH adjusted: yes, the pH of the final test water was adjusted from 7.8 to 7.4 with a diluted hydrochloric acid solution.TEST SYSTEM- Number of culture flasks/concentration: 2 (test item)- Method used to create aerobic conditions: during holding, the sludge was aerated at room temperature until use.CONTROL AND BLANK SYSTEM- Inoculum blank: yes- Toxicity control: yes

Reference substance

Reference substance:

benzoic acid, sodium salt

Results and discussion

Test performance:

The validity criteria of the method were fulfilled. No unusual observations during testing.

% Degradation

Parameter:

% degradation (O2 consumption)

Value:

3

Sampling time:

28 d

Remarks on result:

other: mean value

BOD5 / COD results

Results with reference substance:

The percent biodegradation of the reference item sodium benzoate was calculated based on the theoretical oxygen demand of 1.67 mg/O2/mg. In the procedure controls, the reference item was degraded by an average of 85 % by exposure day 14, thus confirming suitability of the activated sludge. At the end of the test (Day 28), the reference item was degraded by an average of 93 %.

Any other information on results incl. tables

Table 1: Cumulative biochemical oxygen demand (BOD mg O₂/L) in the flask

Time (days)	Test item		Procedure control		Toxicity control
	Flask No.		Flask No.		Flask No.
	5	6	3	4	7
0	0	0	0	0	0
1	0	0	37	36	40
2	0	0	94	94	95
3	0	0	103	104	103
4	2	3	112	114	113
5	4	5	122	123	123
6	6	6	129	130	130
7	6	7	134	134	134
8	8	8	138	138	138
9	8	9	141	142	141
10	10	11	145	146	144
11	12	12	147	148	147
12	14	13	150	152	149
13	14	15	152	154	152
14	16	15	154	156	154
15	16	16	157	160	157
16	-	-	-	-	-
17	18	17	161	162	160
18	18	18	163	164	162
19	20	19	165	166	164
20	20	19	166	166	165
21	20	20	168	168	166
22	20	21	169	168	167
23	20	21	169	168	167
24	21	21	170	168	168
25	23	22	172	170	169
26	23	23	172	170	170
27	23	23	172	172	171
28	23	24	173	172	172

The percentage biodegradation was calculated according to the below given formula:

% biodegradation = (BOD (mg O₂/mg chemical))/ (ThOD_{NH4 or NO3}(mg chemical)) * 100 %

Where:

BOD = Biochemical oxygen demand of the test or reference item

     = (mg O₂uptake/L by test and/or reference item) – (mg O2 uptake/L by inoculum control) / (mg test and/ or reference item per liter)

ThOD_{NH4 or NO3}= Theoretical oxygen demand of the test or reference item without or with nitrification

Table 2: Biodegradation of Oxypicoline RF and the reference item

Time (days)	Percentage Biodegradation*
	Test item based on				Procedure control based on		Toxicity control based on
	ThOD NH4		ThOD NO3		ThOD		ThOD NH4	ThOD NO3
	Flask No.		Flask No.		Flask No.		Flask No.
	5	6	5	6	3	4	7
Mean (Day 28)	3		3		93		not applicable

*corrected for the inoculum controls

Test substance is not inhibitory at tested concentration.

Applicant's summary and conclusion

Validity criteria fulfilled:

yes

Interpretation of results:

other: not readily biodegradable

Conclusions:

The percent biodegradation of the test item was calculated based on the theoretical oxygen demand of 2.31 mg O2/mg test item without nitrification (ThOD(NH4) and 2.54 mg O2/mg test item with nitrification (ThOD(NO3). Consequently, Oxypicoline RF was found to be not biodegradable under the test conditions within 28 days.