In this paper, an attempt is made to review some of the principles that underlie physiological responses following exposure to environmental agents. The review takes the form of the comparison of the health effects from two often competing fuel cycles, nuclear and coal. In addition, efforts will be reviewed to assess the current literature of the health effects of energy systems. This review will not be comprehensive, but will rather indicate briefly those areas where there is general agreement and those where the data are inadequate. 

Although each individual pollutant, whether it be chemical, biological, radioactive, gaseous or solid, has its own peculiarities which requires individual consideration, there are underlying principles which are useful in evaluating and understanding all of them. It was intended, that, by focusing on these two energy systems, theses principles, their uses and abuses could be illustrated.