Biodegradability in seawater according to OECD 306

In the OECD 306 seawater biodegradability test, the test substance is dissolved or dispersed in collected seawater and incubated under aerobic conditions at 15–20°C for up to 60 days. Two methods are available:

  • The shake-flask method tracks ultimate degradation by repeated DOC measurements over time.

  • The closed-bottle method monitors dissolved oxygen consumption at defined intervals (e.g., days 0, 5, 15, and 28).

Results are presented as time-course degradation curves showing lag phase, slope, and t50. For the shake flask method, the biodegradation percentage is typically reported at 60 days, and for the closed bottle method at 28 days. Data are compiled on standardized sheets with validity checks.

OECD 306 is recognised under REACH as a ready biodegradability test method alongside OECD 301 and 310, and data can be submitted in REACH registration dossiers to fulfil information requirements on environmental fate. The method is also listed as an accepted biodegradability test under the REACH microplastics restriction (Commission Regulation (EU) 2023/2055, Appendix 15) and EU Ecolabel criteria for lubricants.

Suitable sample matrices
Polymers, chemicals
Available quality systems
Accredited testing laboratory
Standard
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