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Biodegradation in water: screening tests

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Endpoint:
biodegradation in water: ready biodegradability
Type of information:
(Q)SAR
Adequacy of study:
key study
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: (Q)SAR prediction
Justification for type of information:
QSAR prediction.
Qualifier:
according to guideline
Guideline:
other: QSAR Prediction Reporting Format (QPRF) (JRC version 1.1, May 2008, ihcp.jrc.europe.eu
Principles of method if other than guideline:
(Q)SAR prediction (Catalogic 301C model v.08.11 - July, 2014).
GLP compliance:
no
Oxygen conditions:
aerobic
Inoculum or test system:
not specified
Duration of test (contact time):
28 d
Parameter:
% degradation (O2 consumption)
Value:
33
Sampling time:
28 d
Details on results:
The substance is predicted as not ready biodegradable.

Predicted value (model result CATALOGIC 301C v.08.11 - July, 2014):

BOD= 0.33 ±0.00

Concomitant predictions :

Not ready degradable

Primary Half Life = < 1 day

Ultimate Half Life = 1m 16d

The chemical is predicted as not ready biodegradable. The predicted BOD at 28 day according 301C OECD test protocol is 33%.The substance structure is not known for the model. The structure contains 94.24% unknown structural fragments (-C-CH2-NO3) and 4.76% correct fragments (C(CH2)(CH2)(CH2)(CH2)). For this chemical observed metabolic map was found in the database with observed metabolism data of the model. Sensitivity of the model for the predicted metabolism is 100%.

Please see the attached document (full study report) to see different predictions.

Validity criteria fulfilled:
yes
Interpretation of results:
under test conditions no biodegradation observed
Conclusions:
Pentaerythritol tetranitrate is predicted to be not readily biodegradable based on the (Q)SAR prediction (CATALOGIC Kinetic 301F).
Executive summary:

The target chemical pentaerithrityl tetranitrate is predicted as not ready biodegradable by Catalogic 301C. The predicted BOD at 28 is 33%. Pentaerithrityl tetranitrate was found to be out of structural domain for the Catalogic biodegradation model 301C. The compound has 94.24% unknown structural fragments (-C-CH2-NO3) and 4.76% correct fragments (C(CH2)(CH2)(CH2)(CH2)). Nevertheless, the observed metabolic map of pentaerithrityl tetranitrate was found in the database with documented metabolism data. Sensitivity of the prediction of metabolism is 100%. Therefore, the prediction of the degradation pathway should be considered as an indication for a reliable prediction of BOD.

Endpoint:
biodegradation in water: ready biodegradability
Type of information:
(Q)SAR
Adequacy of study:
key study
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: (Q)SAR prediction
Justification for type of information:
QSAR prediction.
Qualifier:
according to guideline
Guideline:
other: QSAR Prediction Reporting Format (QPRF) (JRC version 1.1, May 2008, ihcp.jrc.europe.eu
Principles of method if other than guideline:
(Q)SAR prediction (CATALOGIC Kinetic 301F model v.11.14 - July, 2014).
GLP compliance:
no
Oxygen conditions:
aerobic
Duration of test (contact time):
28 d
Parameter:
% degradation (O2 consumption)
Value:
7
Sampling time:
28 d
Details on results:
The substance is predicted as not ready biodegradable.

Predicted value (model result CATALOGIC Kinetic 301F v.11.14 - July, 2014):

BOD [28]= 0.07

Concomitant predictions :

Not ready degradable

Primary Half Life = 3.01 days

Ultimate Half Life = 8m 28d

Start day of Calc. 10 days window =>28

BOD calc at 10 days window =?

Classification of Calc. 10 days window = Not Ready

The chemical is predicted as not ready biodegradable. The predicted BOD at 28 day according 301F OECD test protocol is 7%.The substance structure is not known for the model. The structure contains 94.24% unknown structural fragments (-C-CH2-NO3) and 4.76 correct fragments (C(CH2)(CH2)(CH2)(CH2)). For this chemical the observed metabolic map exist in the database with observed metabolism data of the model. Sensitivity of the model for the predicted metabolism is 100%.

Please see the attached document (full study report) to see different predictions.

Validity criteria fulfilled:
yes
Interpretation of results:
under test conditions no biodegradation observed
Conclusions:
Pentaerythritol tetranitrate is predicted to be not readily biodegradable based on the (Q)SAR prediction (CATALOGIC Kinetic 301F).
Executive summary:

The target chemical pentaerithrityl tetranitrate is predicted as not ready biodegradable by Catalogic 301F. The predicted BOD at 28 is 7%. Pentaerithrityl tetranitrate was found to be out of structural domain for the Catalogic biodegradation model 301F. The compound has 94.24% unknown structural fragments (-C-CH2-NO3) and 4.76% correct fragments (C(CH2)(CH2)(CH2)(CH2)). Nevertheless, the observed metabolic map of pentaerithrityl tetranitrate was found in the database with documented metabolism data. Sensitivity of the prediction of metabolism is 100%. Therefore, the prediction of the degradation pathway should be considered as an indication for a reliable prediction of BOD.

Endpoint:
biodegradation in water: ready biodegradability
Type of information:
experimental study
Adequacy of study:
weight of evidence
Reliability:
4 (not assignable)
Qualifier:
no guideline available
Principles of method if other than guideline:
no guideline available
GLP compliance:
not specified
Oxygen conditions:
aerobic
Inoculum or test system:
natural soil
Details on inoculum:
Inocula were prepared from soil. A 1-ml aliquot of soil washings or water sample was inoculated into 24 ml of sterile medium with PETN as sole nitrogen source in 100-ml conical flasks and incubated at 308C on a rotary shaker at 170 rpm.
Duration of test (contact time):
ca. 140 h
Initial conc.:
ca. 1 mmol/L
Based on:
act. ingr.
Parameter followed for biodegradation estimation:
test mat. analysis
Remarks:
Decrease in concentration by HPLC
Parameter:
% degradation (test mat. analysis)
Value:
> 99 - < 100
Sampling time:
100 h
Parameter:
BOD5*100/COD
Value:
> 2 - < 3
Remarks on result:
other: nM
Validity criteria fulfilled:
yes
Interpretation of results:
readily biodegradable
Conclusions:
Pentaerythritol tetranitrate undergoes biotic biodegradation.
Executive summary:

A mixed microbial culture capable of metabolizing the explosive pentaerythritol tetranitrate (PETN) was obtained from soil enrichments under aerobic and nitrogen-limiting conditions. A strain of Enterobacter cloacae, designated PB2, was isolated from this culture and was found to use PETN as a sole source of nitrogen for growth. Growth yields suggested that 2 to 3 mol of nitrogen was utilized per mol of PETN. The metabolites pentaerythritol dinitrate, 3-hydroxy-2,2-bis-[(nitrooxy)methyl]propanal, and 2,2-bis-[(nitrooxy)methyl]-propanedial were identified by mass spectrometry and 1H-nuclear magnetic resonance. An NADPH-dependent PETN reductase was isolated from cell extracts and shown to liberate nitrite from PETN, producing pentaerythritol tri- and dinitrates which were identified by mass spectrometry. PETN reductase was purified to apparent homogeneity by ion-exchange and affinity chromatography. The purified enzyme was found to be a monomeric flavoprotein with a Mr of approximately 40,000, binding flavin mononucleotide noncovalently.

Endpoint:
biodegradation in water: ready biodegradability
Type of information:
experimental study
Adequacy of study:
weight of evidence
Reliability:
4 (not assignable)
Qualifier:
no guideline available
Principles of method if other than guideline:
no guideline available
GLP compliance:
not specified
Oxygen conditions:
aerobic
Inoculum or test system:
mixture of sewage, soil and natural water
Details on inoculum:
Cells were harvested by centrifugation (7,800 3 g for 10 min), washed, and resuspended in 50 mM phosphate buffer (pH 7; 1/10 of the original culture volume). Resting cells (broth grown), this concentrated suspension was further diluted fivefold with buffer before being used. For the preparation of cell extracts, cells in the concentrated suspension were ruptured at 08C by passage three times through a French pressure cell (American Instrument Co., Bethesda, Md.)operated at 126 MPa. Residual whole cells and cell membrane fragments were removed by centrifugation (7,800 3 g for 1 h at 48C).
Duration of test (contact time):
ca. 6 h
Initial conc.:
ca. 0.1 mmol/L
Based on:
act. ingr.
Parameter followed for biodegradation estimation:
test mat. analysis
Remarks:
Decrease in concentration by UV
Parameter:
% degradation (test mat. analysis)
Value:
> 99 - < 100
Sampling time:
100 h
Parameter:
BOD5*100/COD
Value:
> 2 - < 3
Remarks on result:
other: nM
Validity criteria fulfilled:
yes
Interpretation of results:
readily biodegradable
Conclusions:
Pentaerythritol tetranitrate undergoes biotic biodegradation.
Executive summary:

A resting-cell suspension of A. radiobacter grown on GTN as the nitrogen source metabolized 0.1 mM PETN rapidly, within 1.5 h; this was accompanied by a rapid increase in the concentration of a UV-detectable metabolite (designated M3). M3 was transient, and its disappearance was accompanied by the formation of a second metabolite, M2, which achieved its maximum concentration after 3 h. Thereafter, M2 slowly disappeared, and a third metabolite peak (M1; not shown) was observed in HPLC traces; its elution in the water dip precluded accurate peak integration. Without standard compounds to calibrate the HPLC system, the identities of metabolites M1 to M3 remain uncertain. However, by analogy with the sequential denitration of GTN in this bacterium, it is a reasonable working hypothesis that M3, M2, and M1 are the tri-, di-, and mononitrates of pentaerythritol, respectively.

Endpoint:
biodegradation in water: screening test, other
Type of information:
experimental study
Adequacy of study:
supporting study
Reliability:
2 (reliable with restrictions)
Qualifier:
no guideline available
Principles of method if other than guideline:
Water and sediment samples from a local water source were collected to evaluate the effects of biodegradation of PETN in the presence and absence of natural surface water (ASTM, 2001). PETN was introduced into water collected from a field site. The theoretical concentrations of
PETN in both the sediment and field-collected water were at B200 mg/l. A liquid/liquid extraction of water (100 ml) with isoamyl acetate was used, and the extracts were analyzed by GC/ECD. Amended water was fortified with B200 g/l PETN, and an additional 4-l flask of distilled water, sterilized with formalin (80 ml) with the same concentration of PETN, was prepared to determine any possible abiotic effects compared to the amended water. The amended and distilled water samples were sampled for PETN over a period of 34 days.
GLP compliance:
yes
Remarks:
This study was conducted consistent with the standards found in Title 40 US Code of Federal Regulations (CFR), Part 792, Good Laboratory Practices.
Details on results:
The initial PETN concentrations measured for the spiked water and sediment samples resulted in no detection of PETN after 24 hr. Small but measureable amounts of PETN were found after 24 hr in both distilled and amended water. The control water reached a peak concentration of 211 mg/l for PETN after 408 hr (theoretical value 217.5 mg/l). The amended water reached a peak concentration of PETN of 82 mg/l after 216 hr (theoretical value 206.7 mg/l).
Conclusions:
The evaluation of the biodegradation potential of PETN in environmental water and sediment samples suggests that under most environmental conditions, biotic processes are faster in breaking down PETN than the abiotic processes involved in dissolving PETN in water.

Description of key information

Pentaerythritol tetranitrate is predicted to be not readily biodegradable based on (Q)SAR predictions and this value is used for chemical safety assessment. However, a mixed microbial culture capable of metabolizing pentaerythritol tetranitrate was obtained from soil enrichments under aerobic and nitrogen-limiting conditions. A strain of Enterobacter cloacae was isolated from this culture and was found to use PETN as a sole source of nitrogen for growth, suggesting that pentaerythritol tetranitrate may biodegrade in the environment.

Key value for chemical safety assessment

Biodegradation in water:
not biodegradable

Additional information