Table 2.

Currently active biodegradability standards and test methods for plastic materials within marine environments.

standard or test methodinoculummediumtemperature (°C)measurement typetest durationno. of experimental replicatesvalidity criteria
ISO 18830:2016 [44]sediment or sediment and seawatersynthetic or natural seawater15–28 (± 2)BODa; static test conditionsmax. 24 months3greater than 60% degradation of reference material; BOD of negative control must not exceed a specified upper limit
ISO 19679:2016 [45]sediment or sediment and seawatersynthetic or natural seawatersynthetic or natural seawaterCO2 evolution; static test conditionsmax. 24 months3greater than 60% degradation of reference material; CO2 evolved from negative control must not exceed a specified upper limit
ASTM D6691-09 [46]preselected strains or seawatersynthetic; aerobic30 (± 1)CO2 evolution; static test conditionsmax. three monthsNSbgreater than or equal to 70% degradation of reference material
ASTM D7473-12 [47]seawater or a combination of seawater and sedimentdirect exposure to inoculum; aerobiccvaries depending on in situ conditionsvisual evidence for degradation; loss of dry massmax. six months3NSb
ASTM D7991-15 [48]sediment and seawaterdirect exposure to inoculum; aerobic15–28 (± 2)CO2 evolution; static test conditionsmax. 24 months3greater than or equal to 60% degradation of reference material
  • aBiological oxygen demand.

  • bNot specified.

  • cAlthough ASTM D7473-12 states that ‘anaerobic processes (e.g. sulfate reduction) can play a role in the biodegradation', the test material is placed on the sediment surface (which is in direct contact with oxygenated seawater).