The OECD 301 Series of Ready Biodegradability Test Methods A through F plus the OECD 310 Headspace Method all have certain benefits and detractions for their selection as a test method to evaluate chemicals for ‘ready biodegradability’. Each test method prescribes a certain test set-up which are applicable to certain chemical properties such as water solubility, adsorptivity and volatility. The OECD 301B ‘CO2 Evolution Test’ is often recommended to determine the ‘ready biodegradability’ of a chemical due to its direct measurement of CO2 and its relatively large testing volumes along with the maximum amount of inoculum allowed within the OECD 301 Series that often makes it an ideal test. The OECD 301B test is recommended for water soluble, water insoluble and adsorbing chemicals. It is not recommended though for volatile compounds.
Although this guideline is not recommended for volatile compounds since it is a flow-through system, it does have a closed bottle prior to entering the trapping solutions and given its benefits, this presentation assesses the applicability of the OECD 301B Test Method with compounds that are volatile.
The chemical compounds acetone, methanol and hexane representing the ketone, alcohol and alkane chemical groups were chosen for this experiment, conducted according to the OECD 301B guideline while aerating at a slower rate of ~20 cc/minute. The results showed that after 28 days acetone was ‘readily biodegradable’ and hexane was not. Methanol also appears to be ‘readily biodegradable’ although the 10-day window was not well defined. This experiment demonstrates that for certain volatile compounds, the OECD 301B test method may be a viable option for ‘ready biodegradability’ testing.
Sean McLaughlin presented the research during the SETAC North America 43rd Annual Meeting, November 13-17, 2022.
Watch the overview: