Risk Communication Act of 1993 - Requires the Administrator of the Environmental Protection Agency to apply the following principles when preparing risk assessments to assure that such assessments are scientifically objective and inclusive of all relevant data: (1) explicitly distinguish scientific findings in such assessments from other considerations affecting the design and choice of regulatory strategies; (2) consider and discuss both negative and positive laboratory or epidemiological data when presenting assessments of human health risks; and (3) where the assessment process involves selection of any significant assumption, inference, or model: present a representative list and explanation of plausible and alternative assumptions, inferences, or models; explain the basis for any choices; and identify policy or value judgments.

Directs the Administrator, in characterizing risk in any risk assessment document, regulatory proposal or decision, report to the Congress, or other document made available to the public, to: (1) characterize the populations or natural resources at risk; (2) explain the range of exposure scenarios used in the assessment and provide a statement of the size of the corresponding population at risk and the likelihood of the exposure scenarios; (3) provide appropriate comparisons with estimates of other risks; (4) include a statement of any known and significant substitution risks when a risk assessment or characterization for proposed and final regulatory actions is provided; and (5) present the summary of results of an assessment provided by a commenter in any case in which a public commment period is provided with respect to an assessment or regulation.

Requires the Administrator to: (1) issue guidance consistent with the risk assessment principles of this Act and to provide a format for summarizing assessment results; (2) publish a plan to review and revise risk assessments with respect to which new information or methodologies that could significantly alter assessment results become available; and (3) report to the Congress on policy and value judgments which are made in risk assessments for programs under the Toxic Substances Control Act and the effect such judgments have on the regulatory decisions of such programs.