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Environmental fate & pathways

Biodegradation in water: screening tests

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Reference
Endpoint:
biodegradation in water: inherent biodegradability
Type of information:
experimental study
Adequacy of study:
weight of evidence
Study period:
16 August - 19 September 1990
Reliability:
4 (not assignable)
Rationale for reliability incl. deficiencies:
documentation insufficient for assessment
Qualifier:
according to guideline
Guideline:
OECD Guideline 302 C (Inherent Biodegradability: Modified MITI Test (II))
Version / remarks:
An update has been made to the OECD Guideline since the publication of the report.
GLP compliance:
not specified
Specific details on test material used for the study:
Test material: DMAPSA (Octadecanamide, N-(3-(dimethylamino)propyl)-) (CAS No. 7651-02-7).
Date of receipt: 24th July 1990.
Description: White waxy solid.
Storage: In original container at room temperature.
Oxygen conditions:
aerobic
Inoculum or test system:
activated sludge (adaptation not specified)
Details on inoculum:
Inoculum: A mixed population of activated sewage sludge microorganisms.
Source: The aeration stage of Severn Trent PLC Sewage Treatment Plant, Belper, Derbyshire.
Preparation: The activated sludge was maintained at a temperature of 21 ± 1°C for 24 hours. An aliquot of the sludge was added to 10L of diluted water to give a suspended solids level of 111.35 mg/L (100 mg SS/L on dilution for the test) and aerated for seven days prior to the start of the test to reduce the oxygen demand of the control.
Usage rate: Equivalent to 100 mg dry weight/L.
Duration of test (contact time):
ca. 28 d
Initial conc.:
ca. 30 mg/L
Based on:
test mat.
Parameter followed for biodegradation estimation:
O2 consumption
Details on study design:
Duration: 28 days.
Criteria: Oxygen consumption measured by direct manometer reading.
Agitation: By magnetic stirrers.
Temperature: 25 ± 1°C.
Lighting: The test was carried out in darkness.
Observations: Manometers volumes were recorded daily.
Percentage degradation values were calculated by comparison of the oxygen uptake with the Chemical Oxygen Demand (COD). The COD was determined to be 2.12 mgO2/mg.
Reference substance:
aniline
Parameter:
% degradation (O2 consumption)
Value:
ca. 144
Sampling time:
28 d
Details on results:
DMAPSA attained 144 -147% degradation within 28 days calculated from oxygen uptake and so can, therefore, be considered as inherently biodegradable under the strict terms and conditions of the OECD Guidelines. It is suggested that the percentage degradation values in excess of 100% were the result of nitrification hence increasing the oxygen consumption levels.
Results with reference substance:
Aniline attained 66% biodegradation after 7 days and 70% after 14 days thereby confirming the suitability of the inoculum and culture conditions. Total organic Carbon (TOC) analysis showed that aniline attained 99% degradation after 28 days.
Validity criteria fulfilled:
yes
Interpretation of results:
inherently biodegradable
Conclusions:
DMAPSA was shown to be inherently biodegradable.
Executive summary:

The inherent biodegradation of DMAPSA (Octadecanamide, N-(3-(dimethylamino)propyl)-) was assessed by modified MITI method (II) (OECD Guideline 302C).

DMAPSA attained 144 -147% degradation within 28 days calculated from oxygen uptake and so can, therefore, be considered as inherently biodegradable under the strict terms and conditions of the OECD Guidelines. It is suggested that the percentage degradation values in excess of 100% were the result of nitrification hence increasing the oxygen consumption levels.

Description of key information

The inherent biodegradation of DMAPSA (Octadecanamide, N-(3-(dimethylamino)propyl)-) was assessed by modified MITI method (II) (OECD Guideline 302C).

DMAPSA attained 144 -147% degradation within 28 days calculated from oxygen uptake and so can, therefore, be considered as inherently biodegradable under the strict terms and conditions of the OECD Guidelines. It is suggested that the percentage degradation values in excess of 100% were the result of nitrification hence increasing the oxygen consumption levels.

Key value for chemical safety assessment

Biodegradation in water:
inherently biodegradable
Type of water:
freshwater

Additional information