The answer is all the above.
A scientist is someonewho frequently engages in an activity in order to acquire knowledge using a scientific method.
If the scientist is studing the risk of the substance, he needs to acquire the most information as possible, so he:
conducts experiments to identify the hazard,
collects and analyzes risk characterization data,
researches how chemicals react with living cells and
tests the effects of the substance on the populations.
