EU Science Hub

Aquatic toxicity

The assessment of aquatic toxicity is an important component of the environmental hazard and risk assessment of all types of chemicals, and is therefore included in several pieces of EU chemicals legislation.

Aquatic toxicity in general refers to the effects of a chemical on organisms living in water and is determined with organisms representing the three trophic levels:

  • Algae or plants, representing "primary producers"
  • Invertebrates (e.g. crustaceans such as Daphnia spp.), representing "primary consumers/secondary producers"
  • Vertebrates (usually fish), representing "secondary consumers"

EURL ECVAM's work focuses on methods which could replace, reduce or refine the use of fish.

In general, there are acute and chronic endpoints in aquatic toxicity. Acute toxicity is usually determined with short-term exposure of fish to a series of concentrations of a chemical.
The concentration that is lethal to 50% of the test fish is calculated and expressed as LC50 value.

Chronic toxicity is about longer-term exposure. It covers effects on hatching, growth and survival and is used for the determination of NOEC (No Observed Effect Concentration) values, LOEC (Lowest Observed Effect Concentration) or ECx values where x is a % (e.g. 10%) and is concentration of a chemical where 10% of the population show some sort of effect.

Whereas acute aquatic toxicity testing is a basic requirement in most pieces of EU chemicals legislation, chronic aquatic toxicity testing may be required when the outcome of the acute testing indicates a risk, or in the case that long term exposure is expected.

The EURL ECVAM Strategy to replace, reduce and refine the use of fish in aquatic toxicity and bioaccumulation testing (published in 2014) provides an overview of ongoing projects.

Regulatory framework

EURL ECVAM validated test methods

Test methods under validation by EURL ECVAM

Development and optimisation of alternative methods