The introduction of chlorine into water to produce water free of dangers from pathogens (i.e., fit for human consumption) leads invariably to the formation of a wide assortment of organo-halogen compounds, most in very tiny quantities. Since the realization of such reaction products over three decades ago, the question has posed repeatedly: “Is the remedy (chlorination) as bad or worse than the disease (pathogen-induced illnesses)?” The epidemiological approach, applied to assorted circumstances, has suggested some positive, although marginally weak and sometimes contradictory, associations between byproduct consumption and some kinds of cancer and other forms of toxicity. However, the evidence is not sufficiently compelling to clearly support causal relationships. Reliance on laboratory animal studies, while finding clear evidence of a variety of toxic responses when animals were exposed to doses far greater than those experienced by humans, has generally failed to support causal relationships in the range of human consumption and use of tap water. The weight of evidence was examined, using published criteria, for bladder cancer and reproductive impairment. The findings and analytical approaches will be presented. Robert G. Tardiff, Ph.D., ATS, co-founder and President of The Sapphire Group™, is an internationally recognized expert in toxicology and risk assessment with more than 25 years of experience directing and conducting risk assessments and developing risk assessment methodologies for a range of projects. He has been a principal of several major risk assessment firms. Previously, he was Chief of the Toxicological Assessment Branch of the U.S. EPA and Executive Director of the National Academy of Sciences/National Research Council Board on Toxicology and Environmental Health Hazards. He has performed toxicologic interpretations and research, risk assessments and safety evaluations, and regulatory compliance evaluations on chemicals in water, air, and consumer products. His expertise includes scientific evaluation of the toxicity of substances regulated under the major federal environmental statues and under comprehensive state statutes, development of methods in comparative risk assessment and risk communication. Dr. Tardiff is also active as an editor on a number of toxicology and environmental health journals. He has been involved in a number of international seminars and conferences as a member of the organizing group and has close contacts with regulators in many parts of the world including the USA, Canada, and Europe. He has also published numerous books and publications on a wide range of health and toxicologic topics. Dr. Tardiff completed his undergraduate degree in Biology from Merrimack College and his doctorate in Pharmacology and Toxicology from the University of Chicago. Dr. Tardiff has certification as a Fellow from the Academy of Toxicological Sciences and has been honored by the U.S. EPA through their Scientific and Technological Achievement Award – Health Effects; by the U.S. Public Health Service through a Predoctoral Traineeship; and by the Society for Risk Analysis through a Fellowship. Dr. Tardiff has held or currently holds memberships in the Academy of Toxicological Sciences, American Association for the Advancement of Sciences, American College of Toxicology, American Society of Pharmacology and Experimental Therapeutics, Environmental Mutagen Society, International Scientific Group on Methodologies for the Safety Evaluation of Chemicals, International Society for Regulatory Toxicology and Pharmacology, and Society of Toxicology, and was a co-founder and former president of the Society for Risk Analysis.
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