Among the most important characteristics of chemicals in determining their environmental risks is/are:

Among the most important characteristics of chemicals in determining their environmental risks is/are: solubility, reactivity, persistence, and toxicity.

Solubility, reactivity, persistence, and toxicity can all have huge effects on the environment if they are not paid close attention to. 

Hope that helps!
-Chris

Simple multiply 45 units by $0.99you'll get $44.55