Roundtable Discussion Groups Summary Papers: New Bioindicators for Mercury Toxicological Assessment: Recommendations from the First International Bioindicators Roundtable

摘要

At the 14th International Conference on Environmental Bioindicators (14th ICEBI) held in Linthicum Heights, Maryland, USA on 24-26 April 2006, the Conference Chairs and Program Committee initiated the Roundtable Discussion Groups as a prominent and regular feature of this and future conferences. The Discussions are designed to generate focused debate around key topic areas, led by academic, government and industry experts, and are structured to produce definitive papers for peer review and publication in EBI's first-quarter issues of each publication year. The three Roundtables of the 14th ICEBI posed questions revolving around the chosen topic areas of Mercury Bioindicators, Marine Ecosystem-level Indicators, and Regulatory and Policy Uses of Bioindicators, and moved from "what we know" to "where we need to go" and "what are the policy implications from our discussions and conclusions." The paper on coral reef indicators was published in EBI 2(1) and was the first product of this undertaking. The second Roundtable paper on Regulatory and Policy Uses of Bioindicators was published in EBI 2(2). The following paper on Mercury Bioindicators is the final paper of this series. The Mercury Roundtable at the second meeting of the new International Society of Environmental Bioindicators gathered human health, wildlife, and molecularly focused researchers to evaluate the current status of mercury bioindicators. Our goal was to identify a set of indicators, possibly in a tiered approach, suitable for both developed and developing countries, across species (humans, wildlife, rodents) using consistent methods so that the results are comparable over a period of time. The most commonly used indicator of Hg exposure in both humans and wildlife is Hg tissue concentrations. Few bioindicators of effect have been validated for use in both human and wildlife populations, but endpoints that focus on brain development and brain and reproductive function are used in both humans and wildlife, and in both individual and population level evaluations. Endpoints that may be most publicly and politically persuasive include impotence, autism, and cerebral palsy with mental retardation. We recommend additional indicators be used in common across human and wildlife populations. Co-contaminant residues need to be evaluated in tissues, especially selenium, as toxicity is related to the Hg:Se ratio. Further, more species need to be evaluated for the genetic polymorphism (in CPOX4) that leads to a unique Hg-associated peak (iso-keto-porphyrin) in porphyrin profiles in humans and a few non-human species.