Chemical mixtures from a public health perspective: the importance of research for informed decision making.

When considered from a public health perspective, the central question regarding chemical mixtures is deceptively simple: Are current approaches to risk assessment for chemical mixtures affording effective (adequate) and efficient (cost-effective) protection for members of our society? Answering this question realistically depends on an understanding of the hierarchical goals of public health (i.e. prevention, intervention, treatment) and an accurate evaluation of the extent to which these goals are being achieved. To allow decision makers to make informed judgments about the health risks of chemical mixtures, adequate scientific knowledge and understanding must be available to support risk assessment activities, which are an integral part of the regulatory decision making process. Designing and implementing relevant research depends on the existence of a feedback loop between researchers and regulators, where the information needs of regulators influence the nature and direction of research and the information and understanding generated by researchers improves the scientific basis for public health decisions. A clear, consistent, commonly accepted taxonomy for describing important mixture-related phenomena is a key factor in creating and maintaining the necessary feedback loop. Ultimately, both researchers and regulators share a common goal with regard to chemical mixtures; improving the state-of-the-science so that we can make informed decisions about protecting public health. A survey of research issues and needs that are crucial to attaining this goal is presented.