Tar bases, coal, lutidine fraction

Biodegradation in water and sediment: simulation tests

Link to relevant study record(s)

Reference

Endpoint:

biodegradation in water: simulation testing on ultimate degradation in surface water

Type of information:

experimental study

Adequacy of study:

supporting study

Reliability:

3 (not reliable)

Rationale for reliability incl. deficiencies:

unsuitable test system

Principles of method if other than guideline:

Degradation experiments were carried out with undiluted river water taken twice on different days from Ohio River, Great Miami River and Little Miami River. Pyridine, 3-methylpyridine or 4-methylpyridine was added to the test medium at a concentration of 1 ppm. Experiments were conducted in carboys stored at 20 °C. Samples were taken periodically and analysed for content of the test substance.

GLP compliance:

no

Radiolabelling:

no

Oxygen conditions:

aerobic

Inoculum or test system:

natural water: freshwater

Details on source and properties of surface water:

River water was sampled from four different sources:
- Ohio River sampled above Cincinnati
- Ohio River sampled below Cincinnati
- Great Miami River sampled near the mouth
- Little Miami River sampled near the mouth
With the exception of the Little Miami River water, all waters were known to have a history of pollution by wastes which were believed to contain pyridine bases.

Duration of test (contact time):

28 d

Initial conc.:

1 other: ppm

Based on:

test mat.

Parameter followed for biodegradation estimation:

test mat. analysis

Details on study design:

Not reported. The various river waters were each sampled twice on different days. In total, eight degradation studies were conducted for pyridine, 3-methylpyridine and 4-methylpyridine. After dissipation of the initial sample, a second addition of 1 ppm test material was made.

Test performance:

The overall persistence of pyridine in the different river waters ranged from 3 to 6 days. In every case, the second addition of pyridine dissipated more rapidly within 1 to 3 days. In the experiments with 3-methylpyridine, essentially the same pattern was observed with all 4 tested river waters: after a relatively long lag phase of about 10 days, the test substance was removed relatively rapidly within about 5 days. No difference was observed between the different river waters. A relatively similar pattern was observed for 4-methylpyridine, which was reduced below the LOD in all samples within 14 days.

Validity criteria fulfilled:

not applicable

Conclusions:

Pyridine and the pyridine bases 3- and 4-methylpyridine were biodegradable within less than 14 days in samples of freshwater taken from different rivers in the USA. No difference in the microbiological activity was seen between waters with know history of pollution with pyridine bases and those without a pollution history.

Executive summary:

The biodegradation of pyridine and the bases 3-methylpyridine and 4-methylpyridine was tested in a study not following a regulatory guideline or GLP. Freshwater samples were taken from the Ohio River above and below Cincinnati, from the Great Miami River near the mouth and the Little Miami River near the mouth on two different days, so that in total eight different test waters were available. Experiments were carried out with undiluted river waters. The test substances were added at a concentration of 1 ppm in water and test vessels were stored at 20 °C over the test period. Samples were withdrawn from each test vessel and analysed for the test substances periodically. In every case, a second addition of test substance at 1 ppm was made after the first addition had been dissipated, and the procedure was repeated. It was found that pyridine was completely removed in all test vessels within 3 to 6 days, and that removal of the second addition was faster with complete removal after 1 to 3 days. 3- and 4-methylpyridine were also rapidly removed from all surface water samples within about 5 days after a longer lag phase with essentially no removal.

Description of key information

A valid simulation test in water and sediment with the substance is lacking. Simulation studies with a number of surface waters sampled at different locations at different times were conducted with pyridine and methylpyridines. The micro-organisms in these surface waters were all able to rapidly degrade pyridine and methylpyridines under aerobic conditions and at low concentrations within a few days. No differences were found between surface waters having a known history of contamination with pyridine bases and uncontaminated waters.

However, the quality of the available public data is insufficient to derive reliable half-lives in water and sediment that could be used for the assessment of the environmental persistence.