4-vinylpyridine

Endpoint summary

Additional information

The substance 4-vinylpyridine has not been demonstrated to be readily biodegradable, indicating the potential for persistence in the aquatic environment. Therefore, the substance may not be definitively classified as "not P" or "not vP" based upon screening criteria.  Data are not available for the definitive determination of "P"/"vP" properties, and therefore, no conclusion was made.

 

The physical and chemical properties of 4-Vinylpyridine (4VP) determine its environmental fate.  The substance is a liquid with a vapour pressure of 0.228 kPa, so it is moderately volatile. If it is released to air, 4VP is expected to react with atmospheric hydroxyl radicals, nitric oxide radicals and ozone, with a half-life of 1-2 hours, based upon the behaviour of structural analogue 2-vinylpyridine (2VP). Therefore, 4VP is not expected to contribute substantially to air contamination nor to terrestrial toxicity originating from atmospheric sources.

4VP is highly water soluble, at 29,100 mg/l. It has a Henry’s Law constant of 3.62 x 10^-6atm m³/mol, indicating that when 4VP is released to water, it has a limited tendency to partition to the air.  The alkene moiety renders it resistant to hydrolysis. 

 

However, this alkene is reactive and accounts for its functionality as an initiator of polymerisation reactions. It is commercially supplied with a polymerisation inhibitor. In the absence of inhibitor, 4VP autopolymerises or forms reaction products with available acidic or electrophilic substances, and can result in a self-accelerating exothermic reaction. The reactivity of 4VP is also reflected in its corrosive nature in biological systems, as demonstrated with the structural analogue 2VP. The calculated K_ocvalue of 219.5 does not reflect this reactivity.

4VP has not been shown to be readily biodegradable, with negligible degradation after 28 days. This low rate of biodegradation likely resulted from the dilution of the polymerisation inhibitor in the test media, allowing autopolymerisation and/or reaction of 4VP with components of the media. Therefore, while biodegradation was not demonstrated in the biodegradation assays, neither has it been shown that 4VP concentrations remain stable over the timecourse of the test. As a conservative approach, 4VP is considerd to be potentially persistent.

 

4-Vinylpyridine is not bioaccumulative, and is therefore not of concern with respect to food chain exposures (secondary poisoning) or PBT classification.

 

In conclusion, although a definitive determination with respect to the persistence of 4VP in the aquatic environment has not been made, it has been assumed to be potentially persistent based on a lack of ready biodegradability in screening tests (although this is likely due to polymerisation or complexation). Atmospheric or terrestrial exposures to 4VP are not of concern.