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OECD 301

Also known as
OECD 301 ready biodegradability, OECD 301B, OECD 301F

OECD 301 is a set of six standardized laboratory tests, published by the Organisation for Economic Co-operation and Development, used to determine whether a chemical is readily biodegradable. A substance passes by reaching a set level of breakdown within 28 days.

What is OECD 301?

OECD 301 is a test guideline for ready biodegradability. It contains six methods, labeled 301A to 301F, each exposing a chemical to a small population of microorganisms, usually from wastewater treatment sludge, and measuring how much of it is broken down over 28 days. Because the conditions are deliberately stringent, a substance that passes is expected to biodegrade rapidly and completely in the environment.

OECD 301 results are used in chemical registrations such as REACH, in hazard classification, and in ingredient standards such as EPA Safer Choice.

The six methods

MethodWhat is measured
301A DOC Die-AwayLoss of dissolved organic carbon
301B CO2 Evolution (modified Sturm)Carbon dioxide produced
301C MITI (I)Oxygen consumed
301D Closed BottleOxygen consumed
301E Modified OECD ScreeningLoss of dissolved organic carbon
301F Manometric RespirometryOxygen consumed

The method is chosen to suit the substance, for example by its solubility and volatility.

Pass levels and the 10-day window

A substance is classed as readily biodegradable if, within the 28-day test, it reaches:

  • 70 percent removal of dissolved organic carbon, in the methods that measure carbon, or
  • 60 percent of the theoretical carbon dioxide production or oxygen demand, in the methods that measure those.

The pass level must also be reached within a 10-day window, which begins when degradation first reaches 10 percent. The window rules out substances that biodegrade only slowly after a long lag.

Related tests

Substances that fail OECD 301 may be tested for inherent biodegradability under OECD 302, which uses more favorable conditions. OECD 306 measures biodegradability in seawater and is used for substances that may be released to marine environments.

Frequently asked questions

It means the substance reached the pass level, 60 or 70 percent depending on the method, within 28 days and within the 10-day window, so it is classed as readily biodegradable.

OECD 301B, which measures carbon dioxide evolution, and 301F, which measures oxygen consumption, are widely used for surfactants and other organic chemicals.

  • Biodegradability

    Biodegradability is the ability of a substance to be broken down by microorganisms into simpler substances such as carbon dioxide, water and biomass. For chemicals, it is measured by standardized tests that classify a substance as readily biodegradable, inherently biodegradable or persistent.

  • Aquatic toxicity

    Aquatic toxicity is the harmful effect of a substance on aquatic organisms such as fish, invertebrates and algae. It is measured in standardized laboratory tests and reported as values such as LC50 and EC50, the concentrations that affect half of the test organisms.

  • Green chemistry

    Green chemistry is the design of chemical products and processes that reduce or eliminate the use and generation of hazardous substances. It is commonly framed by the Twelve Principles of Green Chemistry set out by Paul Anastas and John Warner in 1998.

  • EPA Safer Choice

    EPA Safer Choice is a U.S. Environmental Protection Agency program that certifies cleaning and other chemical-based products whose every ingredient meets EPA's safety criteria for human health and the environment. Certified products may carry the Safer Choice label.

Sources

  1. OECD Guidelines for the Testing of Chemicals, Test No. 301: Ready Biodegradability, Organisation for Economic Co-operation and Development
  2. OECD Test No. 306: Biodegradability in Seawater, Organisation for Economic Co-operation and Development