Biological effects of low level exposures.

In responding to Drs. Calabrese and Baldwin’squestion, “At what point, if ever, should hormesis beemployed as the principal dose response default assump-tion in risk assessment? “, we examined the benefits ofreplacing traditional dose response with hormesis. Ingeneral, hormesis provides more complete usefulinformation for risk assessment than does traditionaldose-response. A major limitation of using hormesis as adefault assumption in risk estimation is the difficulty ofdifferentiating complex low-level hormetic responsesfrom the placebo effect. A second limitation is thathormesis merely further defines one response. Mosttoxicoses have many responses. The most completeinformation takes all responses and their connectionsinto account.