Tommy R. Shedd

Rapid responses of a melanophore cell line to chemical contaminants in water.

We have evaluated a Xenopus cell line as a potential sensor for detecting toxins in water. X. laevis melanophores responded rapidly by dispersing melanosomes following exposure to six (ammonia, arsenic, copper, mercury, pentachlorophenol and phenol) of 12 tested chemicals in the desired sensitivity range. For two additional chemicals (nicotine and paraquat) the melanophore response improved upon the response capabilities of several available toxicity sensors. These results suggest that a melanophore‐based sensor could be useful for the rapid assessment of chemical toxicity in drinking water. Published 2009 by John Wiley and Sons, Ltd.

Histopathology of Japanese Medaka (Oryzias latipes) Chronically Exposed to a Complex Environmental Mixture

Japanese medaka (Oryzias latipes) were used to evaluate the carcinogenicity of a complex groundwater that contained 5 U.S. Environmental Protection Agency priority pollutant heavy metals and 13 chlorinated aliphatic hydrocarbons. A test protocol that used 10 mg/L diethylnitrosamine (DEN) prior to groundwater exposure was designed to assess both initiation and promotion. The fish were exposed continuously for 9 mo with 0, 1, 5, or 25% groundwater, by volume, with either West Branch of Canal Creek water (Aberdeen Proving Ground-Edgewood Area, Aberdeen Proving Ground, MD) or dechlorinated tap water as the diluent, while concurrent controls were run in the laboratory. Incidental findings included various neoplasms in the nares, ovary, skeletal muscle, skin, swim bladder, testis, thymus, and thyroid. Factors evaluated during statistical analyses of fish neoplasm prevalence included diluent type, groundwater percentage, fish gender, and DEN initiation. Liver neoplasm prevalence was higher in DEN-initiated fish and was frequently higher in males. Concentrations of up to 25% groundwater, by volume, showed no evidence of being a complete carcinogen and showed no consistent, conclusive evidence of being a promoter.

Evaluation of the annual killifish Nothobranchius guentheri as a tool for rapid acute toxicity screening

This study evaluated the use of Nothobranchius guentheri as a novel organism for rapid acute toxicity screening. A major advantage of the species is that there is no need to maintain a continuous culture to have organisms immediately available for testing. Rather, the embryos are viable under long-term storage conditions and can be hatched within a few hours. The tests require only 24 h with standard laboratory equipment. Sensitivity levels for 11 representative toxicants were comparable to those reported for five of the standard U.S. Environmental Protection Agency test species requiring continuous culture.

Aquatic Hazard Assessment of a Contaminated Surficial Aquifer Discharge into the Bush River, Maryland (U.S.A.)

An aquatic hazard assessment of contaminatedgroundwater in a surficial aquifer was conducted at Beach Pointwhich is located in the Edgewood Area of the U.S. Army Garrison,Aberdeen Proving Ground, Maryland. Toxicity was detected atvarious groundwater concentrations by seven of 10 toxicity testsystems exposed to a mixture of heavy metals and chlorinatedaliphatic hydrocarbons. When estimated maximum acceptabletoxicant concentrations (MATC) were established, the data foralgae, invertebrates, and fish suggested that the groundwaterwould not be harmful at a concentration of 10% groundwater byvolume. Likewise, no genotoxicity (Ames and SEC assays),development toxicity (FETAX), or chronic histopathology (9-monthfish test) occurred at 10% groundwater by volume.Near-field (ULINE model) and far-field (dye-tracer model)screening level dilution models were run to estimate the dilutionof the groundwater discharge plume from Beach Point into the BushRiver. The groundwater was considered to be a potentiallyexcessive hazardous material to the biota in the Bush River whena number of conservative assumptions regarding contaminantdistribution and discharge rate of the aquifer were used in thehazard assessment. By modeling the groundwater emanating fromBeach Point as the dilution of a discharge from a line diffuser,the potential water quality impacts were judged to be minimal ifState of Maryland surface water discharge criteria for a mixingzone were used for the discharge of groundwater to the Bush River.

Environmental sentinel biomonitors: integrated response systems for monitoring toxic chemicals

Operational environments for military forces are becoming potentially more dangerous due to the increased number, use, and misuse of toxic chemicals across the entire range of military missions. Defense personnel may be exposed to harmful chemicals as a result of industrial accidents or intentional or unintentional action of enemy, friendly forces, or indigenous populations. While there has been a significant military effort to enable forces to operate safely and survive and sustain operations in nuclear, biological, chemical warfare agent environments, until recently there has not been a concomitant effort associated with potential adverse health effects from exposures of deployed personnel to toxic industrial chemicals. To provide continuous real-time toxicity assessments across a broad spectrum of individual chemicals or chemical mixtures, an Environmental Sentinel Biomonitor (ESB) system concept is proposed. An ESB system will integrate data from one or more platforms of biologically-based systems and chemical detectors placed in the environment to sense developing toxic conditions and transmit time-relevant data for use in risk assessment, mitigation, and/or management. Issues, challenges, and next steps for the ESB system concept are described, based in part on discussions at a September 2001 workshop sponsored by the U.S. Army Center for Environmental Health Research.