Ecological Risk Assessment Model of Chemicals (A-TERAM)

Using the ecological model based on the aquatic food chain to improve the accuracy of the ecological risk assessment of chemical substances

Aquatic Tri-trophic Ecological Risk Assessment Model (A-TERAM)

The impact of chemicals on the ecosystem has been measured in ecotoxicity studies using typical aquatic species of the three trophic levels, i.e., algae (phytoplankton), daphnia, and fish (e. g. medaka fish). A-TERAM aims to more accurately evaluate the effects on the ecosystem by incorporating ecological factors such as the life history of these species and the ecological interactions between species into the model.

Major Features of A-TERAM

Ecological relevance: reflecting inter-specific variation in ecological traits and inter-specific interactions

 In the actual natural ecosystem, organisms play their respective roles. For example, in aquatic ecosystems such as lakes and ponds, algae (phytoplankton) produce organic substances by photosynthesis, and primary consumers such as Daphnia (water flea) feed on the producers and feed themselves as predators, supporting trophic transfers in the ecosystem. Organisms with different trophic status have very different roles in the ecosystem, and even if the effects on the population of each species are at the same level, the effects on the entire ecosystem can be very different.
In addition, the common test species in these three trophic levels, which are algae, arthropod crustaceans (Daphnia), and vertebrate teleost (fish), are far apart from each other in taxonomy. Life history characters are also very different between them. Therefore, even if the ecotoxicity of a chemical substance is evaluated by the same endpoint such as reproductive inhibition, it does not mean that the effect on the population of the species is evaluated by the same criteria. A-TERAM was developed with the aim of renovating the management principles of the ecological effects of chemical substances by considering these differences in the life history of test organisms and their ecological functions in ecosystems. 

Practicality: applicable to ecotoxicity data of a wide range of chemical substances

 A-TERAM has access to much of the ecotoxicity data that complies with the OECD Test Guidelines for freshwater ecosystems. On the other hand, ecological effects can be evaluated only from basic ecotoxicity data and exposure information obtained from three trophic levels (one species at each trophic level). The minimum ecotoxicity data required for A-TERAM are fish acute toxicity (median lethal concentration LC50), acute Daphnia immobilization (50% effect concentration EC50), and algae growth inhibition (no observed effect concentration NOEC or 50% effect concentration EC50). In addition, you can enter the toxicity values for fish growth inhibition (NOEC), fish reproductive inhibition (NOEC), and Daphnia reproductive inhibition (NOEC).
The ecotoxicity information that can be entered includes the results of ecotoxicity tests that comply with the following OECD Test Guidelines (TG). Acute fish mortality: TG203, fish growth inhibition: TG210, fish reproductive inhibition: TG229, acute immobilization of Daphnia: TG202, Daphnia reproductive inhibition: TG211, algae growth inhibition: TG201. These ecotoxicity information covers most of the common ecotoxicity information for freshwater ecosystems.