USGS - science for a changing world

Environmental Health - Toxic Substances



This page is no longer being maintained, and will eventually be phased out. The page will be archived and publicly available once it's phased out.



Biodegradation - "Transformation of a substance into new compounds through biochemical reactions or the actions of microorganisms such as bacteria." - U.S. Geological Survey, 2007

Biodegradation - "A process by which microbial organisms transform or alter (through metabolic or enzymatic action) the structure of chemicals introduced into the environment." - U.S. Environmental Protection Agency, 2009

Biodegradation – “Breakdown of a substance catalyzed by enzymes in vitro or in vivo. This may be characterized for purpose of hazard assessment as:
1. Primary. Alteration of the chemical structure of a substance resulting in loss of a specific property of that substance.
2. Environmentally acceptable. Biodegradation to such an extent as to remove undesirable properties of the compound. This often corresponds to primary biodegradation but it depends on the circumstances under which the products are discharged into the environment.
3. Ultimate. Complete breakdown of a compound to either fully oxidized or reduced simple molecules (such as carbon dioxide/methane, nitrate/ammonium, and water). It should be noted that the products of biodegradation can be more harmful than the substance degraded.” – International Union of Pure and Applied Chemistry, 1993

Biodegradation - "Biotransformation that results in degradation of the pesticide molecule also called biodegradation, although the latter term sometimes refers to degradation processes in which the pesticide serves as a substrate for growth (e.g., Bollag and Liu, 1990)." - Nowell and others, 1999

Biodegradability (or biodegradation potential) - "The relative ease with which petroleum hydrocarbons will degrade as a result of biological metabolism. Although virtually all petroleum hydrocarbons are biodegradable, biodegradability is highly variable and dependent somewhat on the type of hydrocarbon. In general, biodegradability increases with increasing solubility; solubility is inversely proportional to molecular weight." - U.S. Environmental Protection Agency, 2009

Related Definitions


Aerobic Biodegradation


Anaerobic Biodegradation



Electron Acceptor

Electron Donor

Natural Attenuation

USGS Information on Biodegradation

Related Headlines

Other Information on Biodegradation


Bollag, J.M., and Liu, S.Y., 1990, Biological transformation processes in pesticides, in Cheng, H.H., ed., Pesticides in the soil environment: Processes, impacts, and modeling: Madison, Wis., Soil Science Society of America, p. 169-211.

International Union of Pure and Applied Chemistry, 1993, Glossary for chemists of terms used in toxicology: Pure and Applied Chemistry, v. 65, no. 9, p. 2003-2122.

Nowell, L.H., Capel, P.D., and Dileanis, P.D., 1999, Pesticides in stream sediment and aquatic biota--Distribution, trends, and governing factors: Boca Raton, Fla., Lewis Publishers, 1001 p.

U.S. Environmental Protection Agency, 2009, Glossary of technical terms: U.S. Environmental Protection Agency, access date July 21, 2010.

U.S. Geological Survey, 2007, Glossary--Biodegradation: U.S. Geological Survey, access date July 21, 2010.


Disclaimer: The definitions on this page are provided for information purposes only, and do not indicate endorment by the U.S. Geological Survey.

USGS Home Water Climate Change Science Systems Ecosystems Energy and Minerals Environmental Health Hazards

Accessibility FOIA Privacy Policies and Notices logo U.S. Department of the Interior | U.S. Geological Survey
Page Contact Information:
Page Last Modified: Tuesday, 04-Aug-2015 14:26:50 EDT