Pyridoxine hydrochloride

Biodegradation in water: screening tests

Link to relevant study record(s)

Reference

Reference 1

Endpoint:

biodegradation in water: ready biodegradability

Type of information:

migrated information: read-across from supporting substance (structural analogue or surrogate)

Adequacy of study:

weight of evidence

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: The US EPA has compiled a document with robust summaries for Pyridine and Pyridine Derivatives in the context of the HPV program. Each robust summary in this US EPA document has been given a reliability level.

Qualifier:

according to guideline

Guideline:

OECD Guideline 301 B (Ready Biodegradability: CO2 Evolution Test)

Deviations:

not specified

GLP compliance:

no

Inoculum or test system:

not specified

Key result

Parameter:

% degradation (DOC removal)

Value:

100

Sampling time:

21 d

Remarks on result:

other: Pyridine Modified OECD Screening test 21 days

Key result

Parameter:

% degradation (CO2 evolution)

Value:

85

Sampling time:

28 d

Remarks on result:

other: CO2 Evolution test with 3-methylpyridine

Details on results:

Above are just two examples for biodegradability of pyridine and pyridine derivates. In the attached document, all results can be viewed.

Interpretation of results:

readily biodegradable

Conclusions:

Pyridine and Pyridine derivates can be considered readily biodegradable based on the compilation of a large data set in the HPV document.

Reference 2

Endpoint:

biodegradation in water: ready biodegradability

Type of information:

experimental study

Adequacy of study:

weight of evidence

Study period:

21 October 1992 - 3 February 1993

Reliability:

4 (not assignable)

Rationale for reliability incl. deficiencies:

other: see 'Remark'

Remarks:

Although the test was performed according to the OECD 301E (1981) and in compliance with GLP principles, the results of the two replicas showed extreme differences (94% and 0% biodegradation, respectively). It is assumed that the result of the replica without any degradation is caused by a technical error, but no definitive conclusion can be deducted from this test. It is therefore considered not assignable.

Qualifier:

according to guideline

Guideline:

OECD Guideline 301 E (Ready biodegradability: Modified OECD Screening Test)

Version / remarks:

1981

Deviations:

yes

Remarks:

degradation was not seen in one sample

Principles of method if other than guideline:

The deviation from OECD 301E (1981) was that a 0.45 µm filter was used instead of a 0.2 µm filter for DOC analysis.

GLP compliance:

yes

Oxygen conditions:

aerobic

Inoculum or test system:

other: secondary effluent from a sewage treatment plant

Details on inoculum:

- Source of inoculum/activated sludge: mixture of polyvalent bacteria colleted on 6 January 1993. Secondary effluent from the sewage treatment plant of CH-4153 Reinach.
- Preparation of inoculum for exposure: was carried out according to the method described in the guideline. The pH after collection was 7.5.

Duration of test (contact time):

28 d

Initial conc.:

15 - 25 mg/L

Based on:

DOC

Parameter followed for biodegradation estimation:

DOC removal

Details on study design:

TEST CONDITIONS
- Composition of medium: was prepared according to the method described in the guideline.
- Test temperature: 23 ± 2 ºC
- pH: of the effluent was 7.5
- Suspended solids concentration: no data
- Continuous darkness: yes, as the bottles were of dark brown glass.

TEST SYSTEM
- Culturing apparatus: 2000 mL Erlenmeyer flasks (dark brown glass)
- Number of culture flasks/concentration: 2
- Measuring equipment: no details

SAMPLING
- Sampling frequency: on days 0, 7, 14, 21, 27 and 28
- Sampling method: no data

CONTROL AND BLANK SYSTEM
- Inoculum blank: water as specified in the guideline
- Toxicity control: no
- Reference substance tested at 20 ± 5 mg DOC/L


STATISTICAL METHODS:

Reference substance:

benzoic acid, sodium salt

Parameter:

% degradation (DOC removal)

Value:

94

Sampling time:

28 d

Remarks on result:

other: second replicate

Parameter:

% degradation (DOC removal)

Value:

0

Sampling time:

28 d

Remarks on result:

other: first replicate

Details on results:

The results from the two replicates are shown in attached table and graph. One replicate shows absolutely no DOC removal (0% degradation). The other replica shows 99% degradation after 14 days and 94% after 28 days.
The discrepancy between the two replicates could not be explained which renders the test doubtfull as stand-alone.

Results with reference substance:

The reference substance showed a mean biodegradation rate of 94% after 7 days

Validity criteria fulfilled:

yes

Interpretation of results:

other: readily biodegradable in one of the replicates

Conclusions:

For one of the replicates, the substance was considered as readily biodegradable (94% after 28 days). In the other replica flask, no biodegradation occurred (0% after 28 days).

Reference 3

Endpoint:

biodegradation in water: screening tests

Type of information:

(Q)SAR

Adequacy of study:

weight of evidence

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: see 'Remark'

Remarks:

The QSAR models of BIOWIN v4.10 of EPIWEB 4.0 were used in order to gain supplementary information on the biodegradability of the substance as the experimentally determined biodegradability was 94% and 0% in the two replicates respectively. BIOWIN is a known and reliable calculation tool for this endpoint and therefore this estimation can be used in a weight-of-evidence approach to come to a conclusion for biodegradability.

Justification for type of information:

QSAR prediction.

Principles of method if other than guideline:

BIOWIN contains seven separate models.  This version (v4.10) designates the models as follows (see also Boethling et al. 2003):
 Biowin1  =  linear probability model
 Biowin2 =  nonlinear probability model
 Biowin3  =  expert survey ultimate biodegradation model
 Biowin4  =  expert survey primary biodegradation model
 Biowin5  =  MITI linear model
 Biowin6  =  MITI nonlinear model
 Biowin7  =  anaerobic biodegradation model

Biodegradability estimates are based upon fragment constants that were developed using multiple linear or non-linear regression analyses, depending on the model.

GLP compliance:

no

Key result

Parameter:

other: readily biodegradable

Remarks:

readily biodegradable

Remarks on result:

readily biodegradable based on QSAR/QSPR prediction

The details can be viewed in attached print of the BIOWIN v4.10 Results. The prediction indicates that the substance is readily biodegradable.

Validity criteria fulfilled:

not applicable

Interpretation of results:

readily biodegradable

Description of key information

In the OECD 301E (1981) study, pyridoxin-HCl was shown to be readily biodegradable (94% in 28 days) in one replica and not biodegradable (0% in 28 days) in the other replica. 
The structure Pyridoxin was entered into the BIOWIN module of EPISUITE which resulted in a ready biodegradability prediction for the substance.
Pyridine and Pyridine derivates could be considered readily biodegradable based on the compliation of a large data set in the HPV document of the US EPA.

Key value for chemical safety assessment

Biodegradation in water:

readily biodegradable

Additional information

In the OECD 301E (1981) study, pyridoxin-HCl was shown to be readily biodegradable (94% in 28 days) in one replica and not biodegradable (0% in 28 days) in the other replica. As this discrepancy could not be explained, other evidence was used to gain information on the biodegradability. The structure Pyridoxin was entered into the BIOWIN module of EPISUITE which resulted in a ready biodegradability prediction for the substance. The US EPA HPV document on Pyridine and Pyridine derivates included a large data set on the biodegradability in different test systems. Overall it could be concluded that pyridine and methylpyridine were readily biodegradable. Considering all 3 above entries for the weight-of-evidence, the substance pyridoxin-HCl can be considered as readily biodegradable.