The Environmental Protection Administration’s (EPA) Environmental Analysis Laboratory yesterday said it has developed a method for testing the biotoxicity of river water using fish, shrimp, algae and other river plants and animals as indicators.
Biotoxicity testing is conducted by using living creatures to test how the toxins affect their bodies, the laboratory said.
This test can be divided into two types: the first is acute toxicity testing, which evaluates how the toxins affect the survival of the creatures, and the second is long-term toxicity testing, which shows how toxins affect their physiological functions, such as growth and reproduction.
The EPA has been developing different biotoxicity testing indicators and methods to analyze the nation’s rivers since 1993.
Laboratory researcher Yang Hsi-nan (楊喜男) said that living creatures have different sensitivity levels to various kinds of toxins, so using one type of indicator is not enough to adequately test for toxicity, and most methods include at least two kinds of living creatures from different nutritive layers.
“The carp, stone moroko [fish], caridina [shrimp] and water flea are used to test the toxicity in rivers — the first two are vertebrates, while the other two are invertebrates,” he said.
“Since vertebrates and invertebrates have different physiological responses to toxins, we had to choose at least one from each species for each experiment,” he said.
If more than 70 percent of the fish died within 21 days or more than 70 percent of the caridinas or the water fleas died within 48 hours after being put into water suspected of being polluted, then the water will be further examined, he said.
Conducting biotoxicity tests on different concentration levels of water discharged from factories can also help with understanding the level of toxins, he said, adding that the method can also help discover the shortcomings of chemical testing.