On February 24-25, 1999, the AIBS Scientific Peer Advisory and Review Services Division convened a peer review panel to assess the use of sentinel species bioassays by the US Army Center for Environmental Health Research (USACEHR) and conduct cost/benefit analyses to evaluate their current applications. The prospects for further development/validation of these assays, or other techniques, to monitor ecological or human health hazards in military environments (e.g., operational installations, deployments, and closed bases) was also considered. The four bioassays that USACEHR is supporting to evaluate ecological and human health hazards from chemical contaminants were reviewed. A brief description of each bioassay follows:
Developmental toxicity assays are designed to assess the extent to which xenobiotic chemicals affect embryonic development. The Frog Embryo Teratogenesis Assay (FETAX) is one of many bioassays that have significant potential for identifying potential chemicals that may pose human developmental health hazards. Dr. John Bantle (Oklahomas State University) provided an excellent overview of the assay at the site visit. For several years, the research group led by Dr. Bantle has been involved in work funded by the USACEHR in validating the FETAX assay as well as testing chemicals of concern. Dr. Bantle has been highly productive in terms of publications in the peer-review literature.
The bioassay is a 96-hour whole embryo developmental toxicity assay that uses embryos of the frog Xenopus laevis. There are three basic measurements embedded in the assay: 1) embryo death, 2) malformation, and 3) minimum concentration to inhibit growth. Data analysis for the assay is fairly straightforward and involves comparison of concentration-response curves for the above three basic measurements. This enables comparisons among potencies for inducing developmental toxicity.
For more information on FETAX studies point your browser to: www.osu-ours.okstate.edu/report97/AS/zoology.html
Scientists at the University of Montana are involved in research on the use of honeybees as sentinels of the exposure to and effects of environmental contaminants. The team includes an entomologist (Dr. Bromenshenk), an analytical environmental chemist (Dr. Smith), and others involved in the development and operation of state-of-the-art computer and electronic surveillance equipment.
Honeybees make excellent biomonitors of environmental toxicants and have been used by these researchers for years to evaluate trends in environmental exposures to diverse metals, pesticides, radionuclides, industrial solvents explosives and military chemicals.
The approach used by these scientists involves specially designed hives ("condos") equipped with a suite of electronic sensors connected to a bank of computers. Bees from a single colony forage over large areas and come in contact with sediment, water, biota, pollen airborne-particles and environmental contaminants associated with each. Each bee carries with it an electrostatic charge that enhances accumulation of pollen and other small particles. From each hive hundreds of thousands of forays are made each day. Once back at the hive the bees fan the air vigorously to regulate the hive temperature, thereby releasing contaminants into the air. The hives are equipped with air samplers that trap the air-borne contaminants for chemical analysis.
For more information on this project visit www.biology.dbs.umt.edu/bees/default.htm.
Medaka studies focus on oncogene activation, oxidative DNA damage and FT-IR spectral analysis of structural DNA changes associated with carcinogenesis. Applied studies focus on the medaka carcinogenicity assay.
This assay is an excellent approach for monitoring the ability of chemicals, including chemicals in mixtures such as effluents, to induce neoplasia in a vertebrate. Medaka comprise an superb model for this purpose; they are small, adapt well to laboratory culture in small aquaria, withstand stressors such as changes in salinity and dissolved oxygen, and exhibit chemical-induced tumors in a relatively short time (months). These properties allow for rapid and low cost assessment of carcinogens with large sample sizes relative to mammalian models. Moreover, the fundamental biology of cancer appears to be highly conserved among vertebrate models; medaka appear to be a suitable model for many human health and ecological assessments.
Dr. Tommy Shedd (USACEHR) leads the team of investigators who are identifying toxic conditions in water by monitoring the movement patterns and ventilation of the bluegill (Lepomis macrochirus). This assay is useful for human health concerns in that it can be used as an early warning system to identify developing acute toxicity. It is presently in use to monitor treated groundwater (effluent) discharge at Aberdeen Proving Grounds, Maryland.
Methods used to measure the physiological stress on bluegills include changes in movement patterns, cough response, ventilatory rate, and ventilation depth.
The Automated Fish Biomonitoring System has been integrated with the Groundwater Treatment Center at Old O-Field, Aberdeen Proving Ground. When the system identifies a potentially toxic effluent, a sample of the effluent is automatically collected for chemical analysis, a remote monitor within the treatment center identifies the potential problem to facility operators, and if necessary, the discharge is diverted to storage tanks until the problem is resolved.
For additional information on the USACEHR sentinel species research program contact:
Mr. Robert A. Finch, Ph.D., D.A.B.T.
Associate Director for Research
568 Doughton Drive
Fort Detrick, Maryland 21702-5010
For more information on the services provided by the AIBS Scientific Peer Advisory and Review Services please contact:
Mr. Scott Glisson
Director, AIBS SPARS
107 Carpenter Drive, Suite 100
Sterling, Virginia 20164
Washington, DC 20005