Environmental health moves into the 21st century.

Over the past half century, environmental health research has branched from a descriptive, observational process into one of hypothesis driven and mechanistically based science. Nevertheless, the meaning of observed effects of exposures in experimental systems to human public health remains elusive. Recent advances in genetics and "omics" hold great promise to further our abilities to assess potential human health effects and to manage exposures properly. But the comfort of 100% certainty will not be available in the foreseeable future, leaving us with the challenge of designing relevant experiments and test systems upon which to base "logical" policy in risk management.