Ecotoxicology | OECD 201

The Freshwater Alga and Cyanobacteria Growth Inhibition Test (OECD 201) is one of the core aquatic ecotoxicity studies required for environmental risk assessments and product registrations worldwide. With extensive experience in aquatic ecotoxicology, our scientists deliver high-quality studies even for challenging test substances. We serve clients in the chemical, pharmaceutical, biocide, agrochemical, and veterinary sectors.

OECD 201 Test Principle

The study evaluates the effects of a test substance on the growth of freshwater algae during a 72-hour exposure period under controlled laboratory conditions. Growth is measured by changes in cell density, allowing the calculation of internationally accepted regulatory endpoints.

Test Species

•    Desmosmus subspicatus (green algae)

•    Raphidocelis subcapitata (formerly Pseudokirchneriella subcapitata) (green algae)

•    Synechococcus leopoliensis (Cyanobacteria)

•    Anabaena flos-aquae (Cyanobacteria)*

Regulatory Endpoints

•    EC50 (Median Effect Concentration)

•    EC10 (10% Effect Concentration)

•    NOEC (No Observed Effect Concentration), where applicable

•    LOEC (Lowest Observed Effect Concentration), where applicable

Experience with Challenging Test Items

LAUS scientists have extensive expertise in testing substances that require specialised study design, including:

•    Poorly soluble substances

•    Difficult-to-disperse materials

•    UVCBs

•    Coloured substances

•    Volatile compounds

•    Surface-active substances

•    Complex formulations

•    Multi-constituent products

•    Nanomaterials

Where appropriate, we apply approaches such as Water Accommodated Fractions (WAF), solvent-assisted dosing, or other scientifically justified exposure techniques.

OECD 201 Testing of Nanomaterials

We offer specialized study designs for nanomaterials in accordance with current OECD guidance. Our services include dispersibility pre-testing to support exposure strategy development in line with OECD Guidance Document 317 (GD 317), as well as full studies according to OECD 318 (Dispersion Stability of Nanomaterials in Simulated Environmental Media).

In addition, we provide analytical verification of test item concentrations, determination of soluble and particulate fractions, and dynamic light scattering (DLS) measurements for particle size characterization.

Study Scope According to OECD 201

Our standard study package includes:

•    GLP-compliant study conduct according to OECD 201

•    Static exposure design

•    Non-GLP range-finding study

•    Main study with five test concentrations plus untreated control

•    Cell density measurements at 0, 24, 48, and 72 hours using an automated cell counter

•    Analytical verification of test item concentrations

•    Limit test design and non-GLP performance possible

Your CRO for OECD 201 Studies

Scientific Expertise

For more than 25 years our experienced ecotoxicologists and Study Directors have successfully conducted numerous aquatic toxicity studies for international regulatory programs.

Regulatory Confidence

All studies are performed according to Good Laboratory Practice (GLP), ), following validated Standard Operating Procedures (SOPs) and are monitored by an independent Quality Assurance Unit.

High-Quality Data

Our objective is to generate robust, reproducible, and scientifically sound data that withstand regulatory review.

Let's Discuss Your Project

Whether you require a single OECD 201 Algal Growth Inhibition Test or a comprehensive aquatic ecotoxicology testing program, our experts are ready to support your project.

Contact us to discuss your testing requirements, project timelines, and regulatory objectives. We look forward to supporting your next submission with reliable GLP studies and high-quality non-GLP testing.

 

*Conducted in collaboration with a qualified partner laboratory.