Biodegradation Studies

About Biodegradation Studies:

Biodegradation is one of the most important mechanisms for eliminating persistent chemicals from the environment. The wide diversity of microorganisms present in the natural environment and man-made treatment facilities present an abundance of opportunities for biodegradation.   Smithers Viscient has decades of experience conducting biodegradation studies.  Our studies assess a compound’s propensity to be ‘readily’ biodegradable or ‘inherently’ biodegradable based on standard ready biodegradability guidelines or higher tiered inherent biodegradability guidelines as well as simulation studies in activated sludge, water, water/sediment or soil.    Our studies are all designed to accurately determine the standard end-points including percent mineralization (conversion to CO2), half-life and other DTx values as required or requested.  Depending on the study design and purpose, studies are conducted with various inoculums from local waste water treatment facilities, rivers, lakes, ocean, fields and forests.  

Smithers-employee loading samples for testing

‘Ready’ Biodegradation Testing:

‘Ready’ Biodegradation Testing provides indicators for compounds that rapidly biodegrade to carbondioxide when they contact the outdoor environment whether it be a waste water treatment facility, a receiving water body or a farmer’s field.  The criteria needed to meet the status of ‘ReadyBiodegradability” according to the OECD 301 Guideline Series is typically a compound that converts to 60% CO2 within a 10-day window of reaching 10% biodegradation inside a 28-day study.   SmithersViscient can offer a variety of Ready Biodegradation Tests including:

  • OECD 301A: “DOC Die-Away Test”
  • OECD 301B: CO2 Evolution Test
  • OECD 301D: Closed Bottle Test
  • OECD 301E: Modified OECD Screening Test
  • OECD 301F: Manometric Respirometry Test
  • OECD 310: CO2 in Sealed Vessels (Headspace Test)

In recent years, most requests have been for tests which determine the amount of CO2 evolution as an endpoint. All tests listed above have been successfully conducted with challenging test substances thatare adsorptive, insoluble and even volatile.  An example is given below for insoluble and soluble compounds.

Equipment and Instrumentation includes:

  • Walk-in temperature controlled chambers
  • Oxi-Top Respirometer
  • Shimadzu TOC (and TIC) analyzers


‘Inherent’ and ‘Simulation’ Biodegradation Testing (with activated sludge):

For compounds that do not pass ‘ready’ biodegradability standards, which is quite common, inherent biodegradability testing can be performed to further investigate an environmental degradation pathway.  Smithers Viscient offers standard OECD 302 ‘inherent’ biodegradability testing and the activated sludge simulation test under the OECD 303A Guideline using the Porous Pot test design.  Many of these guidelines have been replaced however with the OECD 314 Guideline Series, most notably with:

  • OECD 314B: Biodegradation in Activated Sludge

This design allows for an increase inoculum density similar to that found in most waste water treatment facilities. The guideline also recommends using radiolabeled test substances to allow for lower detection limits, more realistic test concentrations and tracking of metabolites.


Biodegradation in Seawater:

Seawater biodegradation studies are also conducted with local coastal waters collected either from the Massachusetts south coast which catches the warmer seas from the Gulf Stream or collected from the Massachusetts Cape Cod Bay which catches the cooler seas from Canada.  Both test designs described in the OECD 306 Guideline (i.e., closed bottle or shake-flask) can be conducted in our Wareham, MA facility.

Equipment and Instrumentation includes:

  • Walk-in temperature controlled chambers
  • LSC counters
  • Agilent, Shimadzu, Waters HPLC systems
  • Metabolite characterization and identification instrumentation: Sciex 4000 QTRAP® and
  • accurate mass Sciex Triple TOF 5600 Q® mass spectrometers