Historically, which of the following considerations in setting standards for toxic exposure has been emphasized the least?
选项：

A: Including information about how toxins affect natural ecological systems
B: Different members of the population have different sensitivities to toxins
C: Including information about both chronic and acute exposures to a toxin
D: Individuals in the human population have been exposed to many different kinds of toxins that may have additive or synergistic effects
E: All of these considerations have been used and are important in setting policy