Page 17 - Professorial Lecture - Prof Omoregie

 To develop data to better understand biological effects and exposure
 To generate data to support decisions for risk assessment and risk
management
 To meet regulatory requirements to regulate development, manufacture
or release of chemicals
 To determine chemical classifications (and rankings)
 To develop numerical water and quality criteria

Toxicity test methods and designs selected depend on the specific questions to be
addressed. They usually focus on one or more of the following questions (Di Giulio
and Hinton 2008):
 Is the substance lethal to test organisms and at what concentrations?
 What are the effects on organisms exposed to low, sub-lethal
concentrations during part or all of its life cycle?
 What are the effects on short-term exposure and/or sporadic exposure?
 Which indigenous organisms are most sensitive, and what is the
distribution of sensitivities?
 What are the environmental conditions that make the chemical most
toxic?
 What are realistic environmental exposure conditions and what is the
safe concentration of the chemical in the environment?
 What are the effects of mixtures of chemicals being tested?

A typical concentration-response curve

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