Compartmentalization in environmental science and the perversion of multiple thresholds.
Nature and living organisms are separated into compartments. The self-assembly of phospholipid micelles was as fundamental to the emergence of life and evolution as the formation of DNA precursors and their self-replication. Also, modern science owes much of its success to the study of single compartments, the dissection of complex structures and event chains into smaller study objects which can be manipulated with a set of more and more sophisticated equipment. However, in environmental science, these insights are obtained at a price: firstly, it is difficult to recognize, let alone to take into account what is lost during fragmentation and dissection; and secondly, artificial compartments such as scientific disciplines become self-sustaining, leading to new and unnecessary boundaries, subtly framing scientific culture and impeding progress in holistic understanding. The long-standing but fruitless quest to define dose-effect relationships and thresholds for single toxic agents in our environment is a central part of the problem. Debating single-agent toxicity in splendid isolation is deeply flawed in view of a modern world where people are exposed to low levels of a multitude of genotoxic and non-genotoxic agents. Its potential danger lies in the unwarranted postulation of separate thresholds for agents with similar action. A unifying concept involving toxicology and radiation biology is needed for a full mechanistic assessment of environmental health risks. The threat of synergism may be less than expected, but this may also hold for the safety margin commonly thought to be a consequence of linear no-threshold dose-effect relationship assumptions.
Burkart
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W
Institute of Radiation Hygiene of the Federal Office for Radiation Protection, München, Germany. burkart@bfs.de
D004305:Dose-Response Relationship, Drug; D004307:Dose-Response Relationship, Radiation; D004777:Environment; D004781:Environmental Exposure; D006801:Humans; D018570:Risk Assessment / Q000379:methods*