Dibutyl hydrogen phosphate

Biodegradation in water: screening tests

Link to relevant study record(s)

Reference

Reference 1

Endpoint:

biodegradation in water: ready biodegradability

Type of information:

experimental study

Adequacy of study:

key study

Study period:

04/1988

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

guideline study with acceptable restrictions

Qualifier:

according to guideline

Guideline:

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

Version / remarks:

Cited as RG Directive 79/831/ Annex V

Qualifier:

equivalent or similar to guideline

Guideline:

OECD Guideline 301 D (Ready Biodegradability: Closed Bottle Test)

GLP compliance:

no

Oxygen conditions:

aerobic

Inoculum or test system:

activated sludge, domestic, non-adapted

Details on inoculum:

Test organisms
Type : mixed population of aquatic microorganisms (activated sludge)
Origin : aeration tank of a wastewater plant treating predominantly domestic sewage (Wupper area water)
Date of collection : 1988-02-26

Duration of test (contact time):

28 d

Initial conc.:

4.4 other: mL/L

Based on:

test mat.

Parameter followed for biodegradation estimation:

O2 consumption

Reference substance:

aniline

Parameter:

% degradation (O2 consumption)

Value:

3

Sampling time:

5 d

Parameter:

% degradation (O2 consumption)

Value:

0

Sampling time:

15 d

Key result

Parameter:

% degradation (O2 consumption)

Value:

12

Sampling time:

28 d

Results with reference substance:

91 % degradation after 28 days

Validity criteria fulfilled:

yes

Remarks:

positive control (with reference substance) the biodegradation was 91 %

Interpretation of results:

under test conditions no biodegradation observed

Conclusions:

Dibutyl hydrogen phosphate is not readily biodegradable. After 28 days 12 % of dibutyl hydrogen phosphate have been degraded in a Closed Bottle Test.

Executive summary:

A test on ready biodegradability was conducted according to EU method C. 4 -E (Determination of the "Ready" Biodegradability - Closed Bottle Test). After 28 days 12 % degradation of dibutyl hydrogen phosphate was determined and for the positive control (with reference substance aniline) the biodegrdation was 91 %. In conclusion dibutyl hydrogen phosphate is not readily biodegradable.

Reference 2

Endpoint:

biodegradation in water: inherent biodegradability

Type of information:

experimental study

Adequacy of study:

key study

Study period:

05-06/1991

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

guideline study with acceptable restrictions

Qualifier:

according to guideline

Guideline:

EU Method C.9 (Biodegradation: Zahn-Wellens Test)

Deviations:

no

Qualifier:

equivalent or similar to guideline

Guideline:

OECD Guideline 302 B (Inherent biodegradability: Zahn-Wellens/EMPA Test)

Principles of method if other than guideline:

Cited as Directive 87/302/EEC and DIN 38 412 part 25

GLP compliance:

yes

Oxygen conditions:

aerobic

Inoculum or test system:

activated sludge, industrial, adapted

Details on inoculum:

- Activated sludge of aeration tanks of a sewage treatment plant treating predominantly sewage of industrial origin (STP Leverkusen Bürrig)
- Date of collections : 1991-05-22
- Concentration of inoculum (dry weight) : 1000 mg/L

Duration of test (contact time):

28 d

Initial conc.:

100 mg/L

Based on:

DOC

Details on study design:

The substance is dissolved in a mineral medium, inoculated with a mixed population of aquatic microorganisms and 28 days under aerobic conditions were incubated in the dark at 20 – 25°C. The biodegradation of the substance is determined during this time by the decrease of the DOC.

Parameter:

% degradation (DOC removal)

Value:

9

Sampling time:

7 d

Parameter:

% degradation (DOC removal)

Value:

97

Sampling time:

14 d

Parameter:

% degradation (DOC removal)

Value:

> 98

Sampling time:

21 d

Key result

Parameter:

% degradation (DOC removal)

Value:

> 98

Sampling time:

28 d

Validity criteria fulfilled:

yes

Interpretation of results:

inherently biodegradable

Conclusions:

Within 28 days a degradation of > 98 % was determined according to the EU Method C.9 (Biodegradation: Zahn-Wellens Test). Therefore dibutyl hydrogen phosphate is considered to be "Inherently Biodegradable".

Executive summary:

Dibutyl hydrogen phosphate is dissolved in a mineral medium, inoculated with a mixed population of aquatic microorganisms and 28 days under aerobic conditions were incubated in the dark at 20–25°C. The biodegradation of dibutyl hydrogen phosphate is determined using the removal of the DOC. Within 28 days a degradation of > 98 % was determined according to the EU Method C.9 (Biodegradation: Zahn-Wellens Test). Therefore dibutyl hydrogen phosphate is considered to be "Inherently Biodegradable".

Description of key information

Dibutyl hydrogen phosphate is not readily biodegradable. After 28 days 12 % of dibutyl hydrogen phosphate had been degraded in a Closed Bottle Test. Within 28 days a degradation of > 98 % was determined in a Zahn-Wellens Test. Therefore, dibutyl hydrogen phosphate is considered to be inherently biodegradable.

Key value for chemical safety assessment

Biodegradation in water:

inherently biodegradable

Type of water:

freshwater

Additional information

A test on ready biodegradability was conducted according to EU method C.4-E (Determination of the "Ready" Biodegradability - Closed Bottle Test). After 28 days 12 % degradation of dibutyl hydrogen phosphate was determined and for the positive control (with reference substance) the biodegradation was 91 %. In conclusion dibutyl hydrogen phosphate is not readily biodegradable.

To determine the inherent biodegradation, dibutyl hydrogen phosphate was inoculated with a mixed population of aquatic microorganisms for 28 days under aerobic conditions, and incubated in the dark at 20–25°C. The biodegradation of dibutyl hydrogen phosphate is determined via the removal of the DOC. Within 28 days a degradation of > 98 % was obtained according to the EU Method C.9 (Biodegradation: Zahn-Wellens Test). Therefore dibutyl hydrogen phosphate is considered to be inherently biodegradable.