Soil Transformation Studies

Soil metabolism is a critical study in defining a compound’s persistence in the environment, since soil is abundant in microorganisms with P450 enzymes which are uniquely able to metabolize xenobiotics, including pesticides.  Smithers has decades of experience conducting aerobic and anaerobic soil metabolism studies under EPA and OECD Test Guidelines using US and European soils as well as soils from other parts of the world.  Endpoints include DT50, DT75, DT90 along with the identity of any metabolites > 10% for US submission and > 5% at two consecutive time points for European submission.  This information is used to propose a metabolic pathway in soil.

Water /Sediment Transformation Studies

Aerobic and anaerobic aquatic metabolism studies simulate the natural environment, which is generally aerobic in the upper layers of the water and often anaerobic under or near the sediment surface.  Smithers has leading experience conducting these studies with locally collected waters and sediments from both fresh and salt water using both EPA and OECD Test Guidelines.  Other sources and foreign sources of water and sediment can also be procured.  


Aerobic Mineralization in Surface Water

The ‘aerobic mineralization in surface water – simulation biodegradation test’ is designed to determine a test substance’s likelihood of persistence in natural waters.  This test is conducted with relatively low concentrations of the test substance in an environment where the microbiota is in shorter supply than in the other soil and water / sediment tests.   As with the soil and water / sediment tests, similar endpoints are determined and major metabolites are reported along with a proposed pathway.

Staff Poster Publications:

Comparison Of Soil Photolysis In Dry And Moist Soil Layers
Photo-enhanced Soil Metabolism of [14C]Atrazine
An Examination of Sediment Microbial Biomass and the Impact of Seasonal Variation
Identification of New Metabolites of a Pesticide in an Anaerobic Aquatic Metabolism Study
Soil Metabolism of [14C]Acetaminophen in Two Soil Types Using Various Soil Aliquot Sizes
Soil Metabolism of [14C]Atrazine in Two Soil Types Using Various Soil Aliquot sizes