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Definition and Goals

Ecotoxicity in ecosystemszoomEcotoxicology is the study of how chemicals affect the environment and the organisms living in it. Scientists who study the environment tell us that all organisms are connected in the web of life. Therefore, if a chemical affects some of the organisms, other organisms in the ecosystem may suffer since all organisms depend on one another.

The goal of ecotoxicity is to understand the concentration of chemicals at which organisms in the environment will be affected. This concentration should be avoided in order to protect the environment.

To study the possibility that a chemical is toxic, ecotoxicologists usually start with simple approaches. They progress to more complex approaches only when more accurate information is needed. This process is referred to as the "tiered effects process."

What Is Needed?

As scientists move through the tiers, data gets more relevant, but it also takes more time and resources to get the data. Hence, only those compounds used in the highest quantities are tested at the highest tiers (chronic or model ecosystem).

For a population to do well in the environment, they need to:

  • Survive to be old enough to reproduce
  • Grow to be big enough to reproduce
  • Reproduce

Scientists want to make sure that chemicals do not affect these biological processes or endpoints (survival, growth or reproduction). Survival, growth and reproduction at all tiers of toxicity testing cannot be studied, so the tiered effects process is used to study the effect of a new chemical.




QSAR, In vitro, Acute, Chronic, Mesocosm


Chronic, Mesocosm


Chronic, Mesocosm

The effects assessment typically starts with a QSAR approach and progresses to Acute, Chronic, and Model Ecosystem (or mesocosm) testing as needed. Model ecosystems are complex physical environments that combine the control of the laboratory with the realism of the natural world. Ecotoxicity information is combined with fate data in order to reach a decision about whether the ingredients are safe to use in products. These decisions are made in the environmental risk assessment.

Even after scientists are done understanding toxicity and conducting the risk assessment, they are not yet finished. They continue to work to understand the environment and how the chemistry and physical nature of the environment interact to affect the health of the community. This research area is called Eco-epidemiology.


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