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Bioassays: another way to analyze the environment offered by LATU
Bioassays are experimental tests used to evaluate the toxic effects of chemical substances on living organisms. In ecotoxicology, bioassays play a fundamental role by detecting the toxicity of industrial effluents or environmental contaminants in selected species such as microorganisms, plants, and animals. This tool makes it possible to simulate the impact of various chemical compounds on organisms exposed under controlled or natural conditions.
A bioassay consists of exposing an organism to a substance or mixture of substances to observe its biological responses. Results are analyzed to determine parameters such as lethality, growth (increase or decrease in biomass), reproduction, among others, enabling the assessment of acute (short‑term) or chronic (long‑term) effects that the substance may cause in the exposed organism.
Which bioassays does LATU perform?
Through its Water Quality and Environmental Assessment Department, LATU conducts bioassays with organisms from different levels of the trophic chain:
- Aliivibrio fischeri (bacteria)
- Selenastrum (unicellular green algae)
- Lactuca sativa (lettuce)
- Daphnia magna and Ceriodaphnia dubia (crustaceans)
- Pimephales promelas (fish)
Both acute and chronic toxicity tests are performed.
Among the acute tests, those carried out with Daphnia magna and Pimephales promelas are accredited under ISO/IEC 17025 (testing laboratory competence) by the United Kingdom Accreditation Service (UKAS) and the Uruguayan Accreditation Body (OUA).
Why is the development of bioassays important?
The great advantage bioassays offer for advancing scientific knowledge is that they allow inference of toxicity for certain types of organisms before a compound is released into the environment.
Bioassays are often required of companies across various sectors when obtaining permits to operate or when exporting their products. The bioassays to be used are standardized by national and international regulatory bodies.
In this way, bioassays provide a key input for productive enterprises; they are essential for evaluating the safety of effluents and ensuring compliance with environmental regulations.
In 2025, with the publication of Decree 226/025, a new regulation was established for pollution prevention, conservation, and improvement of water quality, which includes bioassay determinations at different levels of the trophic chain.
