THE ENVIRONMENTAL TECHNOLOGY VERIFICATION £EPA PROGRAM ^ ETV Baiteiie U.S. Environmental Protection Agency punjng Tcchnology To Work ETV Joint Verification Statement TECHNOLOGY TYPE: RAPID TOXICITY TESTING SYSTEM APPLICATION: DETECTING TOXICITY IN DRINKING WATER TECHNOLOGY NAME: Deltatox® COMPANY: Strategic Diagnostics Inc. ADDRESS: 111 Pencader Drive PHONE: 302-456-6789 Newark, Delaware 19702 FAX: 302-456-6782 WEB SITE: http://www.sdix.com/ E-MAIL: bferguson@sdix.com The U.S. Environmental Protection Agency (EPA) supports the Environmental Technology Verification (ETV) Program to facilitate the deployment of innovative or improved environmental technologies through performance verification and dissemination of information. The goal of the ETV Program is to further environmental protection by accelerating the acceptance and use of improved and cost-effective technologies. ETV seeks to achieve this goal by providing high-quality, peer-reviewed data on technology performance to those involved in the design, distribution, financing, permitting, purchase, and use of environmental technologies. ETV works in partnership with recognized standards and testing organizations, with stakeholder groups (consisting of buyers, vendor organizations, and permitters), and with individual technology developers. The program evaluates the performance of innovative technologies by developing test plans that are responsive to the needs of stakeholders, conducting field or laboratory tests (as appropriate), collecting and analyzing data, and pre- paring peer-reviewed reports. All evaluations are conducted in accordance with rigorous quality assurance (QA) protocols to ensure that data of known and adequate quality are generated and that the results are defensible. The Advanced Monitoring Systems (AMS) Center, one of seven technology areas under ETV, is operated by Battelle in cooperation with EPA's National Exposure Research Laboratory. The AMS Center has recently evaluated the performance of rapid toxicity testing systems used to detect toxicity in drinking water. This verification statement provides a summary of the test results for the Deltatox® testing system. VERIFICATION TEST DESCRIPTION Rapid toxicity technologies use bacteria, enzymes, or small crustaceans that produce light or use oxygen at a steady rate in the absence of toxic contaminants. Toxic contaminants in drinking water are indicated by a change in the color or intensity of light or by a change in the rate of oxygen use. As part of this verification test, which took place ------- between July 14 and August 22, 2003, various contaminants were added to separate drinking water samples and analyzed by Deltatox®. Response to interfering compounds in clean drinking water also was evaluated. Dechlorinated drinking water samples from Columbus, Ohio, (DDW) were fortified with contaminants at concentrations ranging from lethal levels to levels 1,000 times less than the lethal dose and analyzed. Endpoint and precision, toxicity threshold for each contaminant, false positive/negative responses, ease of use, and sample throughput were evaluated. Inhibition results (endpoints) from four replicates of each contaminant at each concentration level were evaluated to assess the ability of the Deltatox® to detect toxicity at various concentrations of contaminants, as well as to measure the precision of the Deltatox® results. The response of Deltatox® to compounds used during the water treatment process (interfering compounds) was evaluated by analyzing separate aliquots of DDW fortified with each potential interferent at approximately one-half of the concentration limit recommended by the EPA's National Secondary Drinking Water Regulations guidance. For analysis of by-products of the chlorination process, unspiked DDW was analyzed because Columbus, Ohio, uses chlorination as its disinfectant procedure. For the analysis of by-products of the chloramination process, a separate drinking water sample from St. Petersburg, Florida, which uses chloramination as its disinfection process, was obtained. The samples were analyzed after residual chlorine was removed using sodium thiosulfate. Sample throughput was measured based on the number of samples analyzed per hour. Ease of use and reliability were determined based on documented observations of the operators and the verification test coordinator. Quality control samples included method blank samples, which consisted of American Society for Testing and Materials Type II deionized water; positive control samples fortified with zinc sulfate or phenol; and negative control samples, which consisted of the unspiked DDW. QA oversight of verification testing was provided by Battelle and EPA. Battelle QA staff conducted a technical systems audit, a performance evaluation audit, and a data quality audit of 10% of the test data. EPA QA staff also performed a technical systems audit while testing was being conducted. TECHNOLOGY DESCRIPTION The following description of Deltatox® was provided by the vendor and was not subjected to verification in this test. Deltatox® is an in vitro testing system that uses bioluminescent bacteria to detect toxins in air, water, soil, and sediment. Deltatox® is a metabolic inhibition test that provides both acute toxicity and genotoxic analyses. Deltatox® uses a strain of naturally occurring luminescent bacteria, Vibrio fischeri. Vibrio fischeri are non- pathogenic, marine, luminescent bacteria that are sensitive to a wide range of toxicants. When properly grown, luminescent bacteria produce light as a by-product of their cellular respiration. Cell respiration is fundamental to cellular metabolism and all associated life processes. Bacterial bioluminescence is tied directly to cell respiration, and any inhibition of cellular activity (toxicity) results in a decreased rate of respiration and a corresponding decrease in the rate of luminescence. Deltatox® was tested as a stand-alone instrument along with the Deltatox® reagent. The Vibrio fischeri are supplied in a standard freeze-dried (lyophilized) state and, to analyze water samples, are reconstituted in a salt solution, 2.5 milliliters (mL) of the water sample are diluted with 250 microliters (|aL) of a Deltatox® reagent, then approximately 1 mL of water sample is added to 100 |iL of the reconstituted bacteria. Luminescence readings are taken prior to adding the drinking water and then at 5 minutes after the addition. Results are displayed as percent inhibition. To determine whether a contaminant caused detectable inhibition, the inhibition exhibited by drinking water spiked with a contaminant was compared to the inhibition exhibited by the unspiked drinking water. Four replicates of each spiked sample were analyzed. A result was considered positive if the inhibition of the water ------- sample spiked with a contaminant plus or minus the standard deviation of four replicates did not include the inhibition of the unspiked drinking water. Deltatox® is a self-calibrating photometer that incorporates a photomultiplier tube, a data collection and reduction system, and software. Deltatox® can be battery operated and is field-portable, but it does not have temperature- control capabilities. It detects light intensity at 490 nanometers, the wavelength emitted by the bacteria. Deltatox® can store up to 200 data points. These data can be downloaded to a personal computer with Windows® 95, 98, or subsequent operating system, running HyperTerminal/Terminal or a similar program. The data are downloaded as a standard ASCII text file, which can be viewed and edited in any standard ASCII text editor. Deltatox® is 10 inches x 6 inches x 4.5 inches and weighs 5.3 pounds (6 pounds with batteries). It operates on five standard "C" type batteries or a Universal Power Adapter (5.0 V dc @ 4 amps). Deltatox® costs $5,900, and the consumables cost $370 for 100 to 150 tests. VERIFICATION OF PERFORMANCE Endpoint and Precision/Toxicity Threshold: The table below presents Deltatox® percent inhibition data and the range of standard deviations for the contaminants and potential interferences that were tested. The toxicity thresholds also are shown for each contaminant tested. Lethal Dose (LD) Cone. Average Inhibitions at Concentrations Relative to the LD Concentration (%) Range of Standard Toxicity Thresh. Parameter Compound (mg/L) LD LD/10 LD/100 LD/1,000 Deviations (%) (mg/L) Aldicarb 280 72 26 6 -1 1-5 28 Colchicine 240 12 0 3 2 2-9 ND'al Cyanide 250 103 81 14 5 1^ 0.25 Dicrotophos 1,400 65 25 2 -2 2-12 140 Contaminants in Thallium sulfate 2,400 25 14 2 5 1^ 240 DDW Botulinum toxin"" 0.30 -2 -3 -5 -4 1-3 ND Ricin'cl 15 2 -4 3 3 1-5 ND Soman 0.18'dl 2 -6 8 1 3-5 ND VX 0.22 6 2 1 -2 1-6 ND Cone. Average Inhibitions at a Standard Interference (mg/L) Single Concentration (%) Deviation (%) Potential Aluminum 0.36 3 4 interferences in Copper 0.65 38 4 DDW Iron 0.07 -3 6 Manganese 0.26 -2 6 Zinc 3.5 22 6 Ial ND = Not detectable. Ibl Lethal dose solution also contained 3 mg/L phosphate and 1 mg/L sodium chloride. Icl Lethal dose solution also contained 3 mg/L phosphate, 26 mg/L sodium chloride, and 2 mg/L sodium azide. "" Due to the degradation of soman in water, the stock solution confirmation analysis confirmed that the concentration of the lethal dose was 61% of the expected concentration of 0.30 mg/L. ------- False Positive/Negative Responses: There was nearly complete inhibition (false positive responses) in dechlorinated water from the system disinfected by chloramination (88% ± 1%), while the water sample disinfected by chlorination was non-inhibitory (-4% ± 9%). No inhibition greater than the negative control (false negative responses) was detected for lethal doses of colchicine, botulinum toxin, ricin, soman, and VX. Field Portability: Deltatox® and needed accessories were transported to the field location in a hard plastic carrying case provided by the vendor. It was successfully operated on batteries on a small table. A single concentration of cyanide was analyzed in the field and in the laboratory. In the field Deltatox® measured an inhibition of 31% ± 3% in a solution of 2.5 mg/L cyanide versus 14% ± 2% for the same solution in the laboratory. Despite the different inhibitions, Deltatox® seemed to function properly. Other Performance Factors: The pictorial manual was useful, operation was straightforward, and sample throughput was 20 samples per hour. Although the operators had scientific backgrounds, based on the observations of the verification test coordinator, an operator with little technical training would probably be able to follow the manual instructions to analyze samples successfully. Original signed by Gabor J. Kovacs 11/13/03 Gabor J. Kovacs Date Vice President Environmental Sector Battelle Original signed by Timothy E. Qppelt 12/1/03 Timothy E. Oppelt Date Director National Homeland Security Research Center U.S. Environmental Protection Agency NOTICE: ETV verifications are based on an evaluation of technology performance under specific, predetermined criteria and the appropriate quality assurance procedures. EPA and Battelle make no expressed or implied warranties as to the performance of the technology and do not certify that a technology will always operate as verified. The end user is solely responsible for complying with any and all applicable federal, state, and local requirements. Mention of commercial product names does not imply endorsement. ------- |