Superfund Research Program
The Use of Wildlife Biomonitoring at Hazardous Waste Sites
Much of the decision making associated with chemically contaminated waste sites is based on the risks that the contaminants pose to human health. Though human populations are of primary concern in cleaning up these sites, the wildlife inhabiting the sites are intimately associated with the contaminated environment and thus are front line indicators of chemical exposures and contaminant-mediated health effects. Monitoring the health of these wildlife can provide important information about the bioavailability of contaminants on hazardous waste sites.
Scientists from the Institute of Environmental & Human Health at Texas Tech University (a part of the University of Washington Superfund Basic Research Program) have shown that wildlife biomonitoring provides a practical and sensitive means for determining whether the contaminants at hazardous waste sites find their way into the food chain at biologically significant levels. By monitoring specific health endpoints in indigenous wildlife during and after clean-up activities, the scientists have been able to determine the biological effectiveness of remediation efforts. Their largest application of biomonitoring at a hazardous waste site is at the Rocky Mountain Arsenal located approximately 10 miles from downtown Denver.
During its 50 years as an active Army installation, the Arsenal was a site of manufacture for chemical warfare agents, incendiary munitions, and pesticides. Now the U.S. Fish and Wildlife Service is working to transform this formerly "top secret" operation into a National Wildlife Refuge. The conversion from a Superfund hazardous waste site to a wildlife refuge is being aided by the Texas Tech scientists who are working in collaboration with the Fish and Wildlife Service to investigate the health of wildlife populations living in the Arsenal.
The site has much to offer wildlife populations. It encompasses 27 square miles of varied territory including prairie, wetlands, lakes, and rolling uplands. Approximately 250 species of wildlife live on the site including bald eagles, coyotes, deer and badgers.
However, the chemical contamination at the Arsenal may present potential health risks to the wildlife. The main chemical of concern is dieldrin, an organochlorine insecticide found to suppress the immune system and damage the liver in laboratory animals. Dieldrin is highly concentrated in a region of the Arsenal where production wastes were discharged into open basins for evaporation. Wind borne dusts from those basins transported dieldrin throughout the Arsenal where low level contamination poses the dilemma of whether to remediate or preserve the natural habitats for the indigenous wildlife.
Wildlife health has been monitored at the Arsenal from the most contaminated areas to those considered undisturbed in order to determine where dieldrin's effects occur, and at what soil concentrations. The field work at the site is applying biomarkers that were developed at Texas Tech University and the University of Washington. These biomarkers include reproductive success, cytochrome P450 activity, cellular and humoral immune function and porphyrin profiles. The wildlife under observation include rodent and starling populations.
Rodent demographics were particularly sensitive to dieldrin exposure. With increasing soil concentrations of the insecticide, rodent communities were less diverse. Most species, except for deer mice, were absent from areas of high dieldrin concentrations. In the most contaminated areas the deer mice showed a decreased life expectancy and increased reproductive rates suggesting that a shift to less sensitive, quickly reproducing species had occurred.
A significant advantage for the use of starlings in biomonitoring is that nest boxes can be easily constructed and placed at specific locations on hazardous waste sites. Indigenous starlings will nearly always inhabit them. Furthermore, the birds sample the food chain, soil, water and air for all potentially bioavailable contaminants. Thus, they may respond to the impacts of complex mixtures of contaminants from multiple pathways of exposure. The effects of multiple and diverse exposures would be impossible to assess based on individual chemical toxicity analyses alone.
The impact of dieldrin on the starlings was highly variable depending on the location of their nest boxes. Nest boxes located in areas of high contamination resulted, in some cases, in outright mortality of the birds. Intermediate effects include reproductive failure. Starlings from nest boxes located in areas of low contamination showed no apparent effects. Thus, these studies demonstrated where the contaminants in the soil were bioavailable at toxicologically significant levels.
These results indicate that scientists may be able to use some species to determine whether certain contaminants at hazardous waste sites exist in levels that are harmful to wildlife. Health effects endpoints were successfully introduced into the remediation site assessment of the Rocky Mountain Arsenal where the results of the panel of bioassays and contaminant analyses of soil were used to make decisions about site remediation. The importance of these techniques lies in real effects-oriented assessments that can complement standard chemical analyses in the determination of site risk.
Utilizing this health effects biomonitoring approach, the Texas Tech researchers are assisting the U.S. Fish and Wildlife Service in monitoring the biologically effective clean-up of the Arsenal. Biomarker determinations have also been incorporated into the long term biomonitoring program at the site. Furthermore, the Fish and Wildlife Service is incorporating this approach to site assessment at other sites where impacts of contaminants on wildlife are of potential concern.
The scientists applied wildlife biomarker techniques in several other field studies at the following National Priority List sites:
- In Pickens County, South Carolina at the Sangamo-Westin site which is contaminated with PCBs;
- In Charleston County, South Carolina at the Geiger site which is contaminated with oil, metals, and PCBs;
- In McKracken County, Kentucky at the D.O.E. Paducah Gaseous Diffusion Plant which is contaminated with radionuclides, PCBs and heavy metals;
- In Island County, Washington at the Naval Air Station, Whidbey Island which is contaminated with PAHs and heavy metals; and
- In McIntosh County, Alabama where swampland adjacent to two industrial plants is contaminated with DDT and Mercury.
Now the E.P.A. - Region 8 is considering applying these techniques to large mining sites within the region. Risks to wildlife have been suggested based on modeling that evaluated contaminant uptake from foraging, food chain movement, drinking water and soil ingestion. Modeled wildlife often include species such as the white-tailed deer, deer mouse, American robin, red fox, and American kestrel. However, direct assessment of wildlife on chemically contaminated sites is usually limited.
This research demonstrates the benefits of applying wildlife health assessment techniques at hazardous waste sites. In general, wildlife biomonitoring can aid in remediation decision making by providing:
- a means for evaluating the biological effectiveness of clean-up efforts;
- a means for determining when clean-up objectives have been achieved;
- a model system for evaluating the risks associated with real-life exposure routes and doses; and
- a means for testing the validity of laboratory generated models of exposures and effects.
For More Information Contact:
To learn more about this research, please refer to the following sources:
- Cobb GP, Wood PD, O'Quinn M. 1997. Determination of PCBs in eggs and chorioallantoic membranes of American alligators (Alligator mississippiensis). Environ Toxicol Chem 16(7):1456-1462.
- Rummel KT, Akins JM, Dickerson RL, Hooper MJ. 1996. Porphyrin profile alterations from subchronic 2,3,7,8-tetrachlorodibenzo-p-dioxin exposure in non-traditional laboratory species. Organohalogen Compounds 29:257-261.
- Dickerson RL, Hooper MJ, Gard NW, Cobb GP, Kendall RJ. 1994. Toxicological foundations of ecological risk assessment: Biomarker development and interpretation based on laboratory and wildlife species. Environ Health Perspect 102(Suppl12):65-69. PMID:7713037
- Hooper MJ, LaPoint TW. 1994. Contaminant effects in the environment: Their use in waste site assessment. Cent Eur J Public Health 2:65-69. PMID:7697047
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