Environmental Fate and Degradation Testing

Brixham Environmental Laboratory has a widely experienced and newly expanded Environmental Fate Unit providing a comprehensive service in support of product registration and effluent management. Studies available include a range of tests of ready & inherent biodegradation and inhibition in waters and soils, such as OECD 303* and OECD 308**, and for the assessment of partitioning between environmental compartments.

In order to assess the potential impact of chemical substances upon the environment, a realistic estimation of their probable environmental concentrations is required. This would normally include an assessment of their potential to degrade and partition between environmental compartments.

The extent and rate to which biodegradation of substances is likely to occur is an important part of the information needed to assess their environmental fate. It may also be prudent, if not necessary, to have some knowledge of the metabolic pathways through which biodegradation occurs.

Brixham Environmental Laboratory investigates aerobic biodegradation via a suite of test procedures that are designed to satisfy the requirements of the current OECD and USA FDA and EPA guidelines. The methods are best suited to pure substances of known water solubility, volatility (defined vapour pressure) and hydrolytic stability. Where a suitable radio-isotope is available for use, methods are available based upon the quantification of evolved carbon dioxide.

The suite of microbial toxicity, degradation and environmental fate tests available at Brixham Environmental Laboratory are shown below:

Toxicity assessment & screening tests

• Microbial toxicity - ASRIT (OECD 209, OPPTS 850.6800)
  
• Toxicity to Pseudomonas putida
  
• Nitrification inhibition
  
• Anaerobic degradation inhibition
  
• Cellsense
  
• 5 day biochemical oxygen demand (BOD5),
  
• chemical oxygen demand (COD) and
  
• organic carbon analysis.

Ready biodegradation tests:
 

• DOC die-away test  (OECD 301A)
  
• 28 day Sturm (CO2 evolution  (OECD 301B)
  
• Modified MITI manometric test  (OECD 301C)
  
• Closed bottle BOD28 (OECD 301D)
  
• Modified OECD screening test (MOST)  (OECD 301E)
  
• Manometric respirometry (Hach - MITI)  (OECD 301F)
  
• Ready biodegradability  (OPPTS 835.3110)
  
• Closed bottle CO2 evolution  (ISO)
  
• Seawater biodegradation  (OECD 306)

• Sewage Treatment Simulation: Activated Sludge Units (OECD 303A)

• Sewage Treatment Simulation: Biofilms (OECD 303B)

• Transformation in soil (OECD 307)

• Transformation in sediment (OECD 308)

*The OECD 303 Guideline is designed to determine the elimination and biodegradation of water-soluble organic compounds by aerobic micro-organisms.

**The OECD 308 Guideline describes a laboratory test method to assess aerobic and anaerobic transformation of organic chemicals in aquatic sediment systems. Studies of this type are required for chemicals which are likely to reach the aquatic environment by routes such as direct application, spray drift, run-off, drainage or waste disposal.

Abiotic degradation tests:

• Photolysis (SETAC, OPPTS 835.2210)
  
• Inherent biodegradation tests :
  · Semi-continuous activated sludge (SCAS)  (OECD 302A, OPPTS 835.3210)
  
• Zahn-Wellens (OECD 302B, OPPTS 835.3200 )