The Army’s drinking water surveillance program Last year, 53 chemical and physical parameters were analyzed from 827 water sources from installations throughout the world; medically significant constituents exceeding acceptable limits are flagged and, if necessary, the water source is closed down
Paul V. Sneeringer, Frederic Belkin, Nicholas Straffon, and Sandra A. Costick U.S. Army Environmental Hygiene Agency Aberdeen Proving Ground, Md. 2 10 10
In July 1970, the Public Health Service (PHS) released a report entitled “Community Water Supply Study, Analysis of Survey Findings.” This report concluded that increased population and industrial development caused surface and groundwater pollution; a significant percentage of community water systems did not meet the minimum drinking water standards established by PHS in 1962, and chemical surveillance of drinking water sources was inadequate. Several years later, the “Safe Drinking Water Act,” enacted by Congress in December 1974, made chemical surveillance of drinking water sources to assure compliance with standards federal law. Until 1972, chemical surveillance of Army drinking water sources had periodically been conducted by the US. Geological Survey on a contractual basis for the Army Corps of Engineers. As a consequence of the PHS report, the Surgeon General of the Army charged the US. Army Environmental Hygiene Agency (USAEHA) in July 1972 with the mission of monitoringthe quality of drinking water. Chemical analyses, number of sources to be monitored, and the establishment of an analytical quality-assurance program were efforts undertaken to upgrade surveillance. Surveillance program Under the auspices of the U S . Army Drinking Water Surveillance Program (USADWSP), water samples are collected annually from Army installations in the US., Puerto Rico, the Panama Canal Zone, Alaska, the Pacific area, and Asia. Both ground- and surface-water sources, treated and untreated, are sampled. For example, in calendar year 1976 a total of 827 sources were sampled (Table 1). Surface-water sources are sampled and analyzed annually for 53 chemical constituents (minerals, nutrient, metals, pesticides and radiological analyses), and physical parameters that are grouped according to type and complexity of analysis, container, and preservation requirements. Groundwater sources are sampled and analyzed annually for all of the above constituents, excluding pesticides, which are determined on a triannual basis. Collected samples are forwarded by mail to regional USAEHA laboratories where respective general analyses are performed. These analyses are conducted at the regional laboratory in order to minimize the time interval between collection and analyses and, hence, sample deterioration. Portions of samples are forwarded by the three regional laboratories to the main USAEHA laboratory for the more complex metals, pesticides, and radiochemicals analyses. Information transfer Analytical data are collected and stored on IBM computer cards. A separate card is used for each analysis and a deck of cards corresponds to a total sample analysis. On the computer cards, each water source is identified by a six-digit installation code and by an alpha numeric code designating the respective water source as a numbered raw, treated, surface, ground or mixed source. Upon completion of the general analyses, the regional laboratory forwards the data cards to USAEHA for processing. All samples and data cards are received, unpacked, logged, numerically labeled, and distributed by USAEHA’s Analytical Reference and Quality Assurance Division to various analytical chemistry laboratories at USAEHA for specific analyses. Metal analyses are performed by the Environmental Chemistry Division (ECD), pesticide analyses by the Pest Management and Pesticide Monitoring Division (PMPMD) and radiochemicalanalyses by the Radiological and Biological Chemistry Division (RBCD). Coordination of the Army’s surveillance program is performed by Analytical Reference and Quality Assurance Division (ARQAD) as shown in Figure 1. Upon completion of the required analyses and confirmation of the data by ARQAD, the samples and containers are discarded. The data are collated by ARQAD into completed sample decks and forwarded to the Data Processing and Technical Information Branch (DP&TIB) for keyVolume 11, Number 8, August 1977
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punching, programming, and printout. A condensed final report for a water source is pictured in Figure 2. To aid in interpretation of the engineering and medical aspects, the constituents are categorized as operational management, aesthetic acceptability, indicator anion, and medical acceptability. In a column adjacent to the observed analytical results, reference concentrations are printed for guidance in the interpretation of the observed results. These reference concentrations are based on the 1962 PHS standards, as revised by the U.S. EPA, with the exception of those listed for gross alpha, gross beta, and chromium; analytical procedures for these are utilized for screening purposes for radium-226, strontium-90, and chromium (VI), respectively. The ratios of observed constituent concentrations to the reference concentrations (where applicable) are calculated and listed as percentages. All values of 100% or more initiate a “flagging action” and cause an asterisk to be placed adjacent to the constituents’ names. Completed grintout reports are checked by ARQAD and forwarded to the Water Quality Engineering Division (WQED) for interpretation and followup action as needed. Copies of each report are forwarded by WQED to the regional laboratories along with an interpretation of the potability or safety of the drinking water. The regional laboratories, in turn, distribute the reports to installations.
If a flagging action occurs in the category of medical acceptability for any water source, recollection is initiated and a larger sample is taken for constituent analyses. If, upon repeated analysis, the concentration of a constituent in the medical acceptability category again exceeds the reference concentration, WQED begins extensive sampling and analyses of the water source and a survey of the water system and population affected. As a result of such investigation, the water source may be declared nonpotableand the source closed or a treatment process recommended. Quality-assurance program The large amount of data generated from analyses of drinking water samples are interpreted by medical and engineering personnel with respect to health, environment, and equipment operation. Health-related aspects are considered most important. Of secondary significance are data used to assess the status of treatment and purification systems. In order to allow correct decisions to be made from the interpretation of reports, a viable analytical quality-assurance program is a major part of the surveillance program. The quality-assurance program includes: utilization of standard analytical procedures laboratory accreditation intra-laboratory quality control proficiency analytical testing external quality control aniodcation balancing of sample analytical data automated data transferral systems laboratory consultation visits and training calibration service Environmental Science & Technology
In Table 2 are listed some of the parameters measured and the detection limits established in the surveillance program. Measurement procedures are those analytical methods found in Standard Methods for the Examination of Water and Wastewater. For the chemical constituents in the category of medical acceptability, it is most important that the detection limits be less than the respective reference limits. Accuracy (closeness of results to true values) and precision (reproducibility of results) guidelines have been established for those constituents found to be relatively stable in aqueous solution. These guidelines are also detailed in Table 2; accuracy is expressed as relative error and precision as relative standard deviation. These guidelines represent average laboratory performances observed over a 1-y period. ARQAD monitors adherence by the main USAEHA and three regional laboratories to these guidelines and detection limits. Under this surveillance program, the metals and radiation laboratories participate in the accreditation program conducted by the American Industrial Hygiene Association and sponsored by the National Institute for Occupational Safety and Health (NIOSH). The accreditation provides assurance that these analytical laboratories are state-of-the-art. Quality control, testing There are many procedures that can be performed daily by a laboratory to enhance analytical performance and all can be grouped under the heading “intra-laboratory quality control.” These procedures include date labeling of reagents, cleanliness of laboratories, preparation of the more unstable chemical working standards on a daily basis, proper standardization and frequent preventive maintenance of analytical equipment. The list is long and can be found in manuals published by U S . EPA and NIOSH. Suffice to say, ARQAD promotes the use of analytical quality-control charts described in these manuals. Duplicate results from daily repetitive analyses of a stable sample are plotted in terms of mean and range. The constituents measured for this purpose are those routinely analyzed by the various laboratories at concentrations generally encountered in the surveillance program, or concentrations equivalent to or near the health reference levels. Initial repetitive measurements are used to establish statistical control limits about the average observed concentration, and the mean range of the sets of duplicate results. The control limit values represent standard deviations about a normal distribution of results from repetitive analyses of the same sample. Detailed contingency plans for checking instrument operation, and analytical methodology are then devised for results that fall outside of the control limits. For the pesticide laboratory, the control sample turns out to be a large volume (6 L) of aqueous solution of various pesticides (DDT, dieldrin, heptachlor epoxide and lindane) known to be stable in water for long periods. The control samples used by the other laboratories are similar in terms of volume and medium, but differ in constituents according to the analyses performed by the laboratories. The quality-control charts are valuable in that their use allows the surveillance program laboratories to control a wide variety of systematic and random error sources in analytical systems. Daily obtainment of results within the statistical limits documents the correct operation of instruments, reagents, and techniques. Proficiency analytical-testing services are provided for the regional laboratories by ARQAD on a quarterly basis. Ampoules of concentrated controls consisting of chemical constituents categorized as general analyses are prepared, measured by ARQAD for confirmation purposes and distributed quarterly to all analysts in participating laboratories. The analysts, unaware of the true concentrations, perform quantitative analyses and report subsequent results to ARQAD. The results are statistically analyzed for accuracy and precision, and reports evaluating performances of the analysts are returned to the participating scientists. Those constituents for which survey results indicate excessive error are identified and analytical operations for the constituents are stopped until the problems are resolved.
For pesticides and radiochemicals, proficiency testing services are provided by the U.S. EPA. Standards consisting of radioisotopes in water are distributed bimonthly by the agency's radiochemistry quality-control laboratory in Las Vegas. ARQAD then distributes them to the radiochemistry laboratory. The analytical results are forwarded to EPA for statistical treatment and comparison with numerous other laboratories; EPA then sends a report of findings to ARQAD for distribution. Pesticide standard solutions are also received occasionally from EPA as part of collaborative studies, and ARQAD coordinates the participation of the pesticide laboratory. For the Army's Environmental Hygiene Agency laboratories, ARQAD independently determines the accuracy and precision of the various analytical systems. The accuracy and precision guidelines in Table 2 are utilized by ARQAD to assess the quality of analytical data generated under the Army's surveillance program. The samples collected by regional laboratories arrive each month at USAEHA for distribution to the pesticide, metal, and radiochemistry laboratories. The batches generally contain
50-60 samples for each laboratory. Prior to sample distribution, chemical controls are prepared and distributed to the laboratories together with the samples. After analysis by the respective laboratories, the control data are returned to ARQAD for review. If the control data are in agreement with accuracy and precision guidelines, then the corresponding sample data are sent to DP&TIB, which compiles the final report. If the control data are inaccurate or imprecise, the respective laboratories are consulted and the particular batch of samples is reanalyzed after resolution of analytical discrepancies. Aniodcation balancing Validation by ARQAD of the quality of the data received from the regional laboratories is accomplished in a different manner as geographical separation from USAEHA prevents the use of chemical controls with the incoming samples. Advantage is taken of the fact that concentrations of negatively and positively charged ionic species in water must balance to zero. All of the cations and anions normally found in relatively high concentrations in drinking water are included in the balance. This quality-assurance technique, termed "anion-cation balance", is described in Standard Methods for the Examination of Water and Wastewater. Limits of three standard deviations about zero are imposed on the regional laboratories. Forms for listing these standard deviations are provided to the regional laboratories, which then forwards them along with respective sample data to ARQAD. Data transferral system In any technical program involving a large amount of analytical data, an effective yet economical data transferral system is needed to minimize transcription errors. The present transferral system used in the Army's water surveillance program makes use of keypunching operations and data-acquisition systems available on some of the analytical instrumentation. Punched paper-tape data are converted by machine onto data cards, collated, and added to the pesticide, radiation, and general analyses data to complete sample decks. A computer program has been designated to perform the aniodcation balance. Since regional laboratories have already balanced the data, failure of the data to balance under the computer program indicates keypunch errors that are subsequently corrected. The computer program also calculates total hardness values from calcium and magnesium concentrations and compares these results to the experimental values obtained by titration at the regional laboratories; specific conductance
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values are compared to total dissolved solid values; experimental total dissolved solid values are compared to dissolved solid values calculated to reflect the sum of all the constituent concentrations. Any discrepancies noted in the above data indicate keypunching errors that are corrected prior to the development of final reports. Results of the surveillance program Tabulated in Table 3 are the frequencies with which medically significant contaminants exceeded their health-reference concentration limits for total numbers of samples collected and analyzed each year. In general, it was program policy to sample the same drinking water sources each year. The medically sigrtificant category includes radiation measurements, heavy metals, fluoride, nitrate, and pesticides. As reference limits are exceeded the problem constituents are asterisked (flagged) in final reports. These flags are the most significant results in the program as they indicate possible health problems related to drinking water sources. Most of the flags occur under the categories of radiation and heavy metal. Although a reference concentration of 3 picoCuries/liter (pCi/L) was established as the Public Health Standard for radium-226 in 1962, a reference concentration of 5 pCi/L for gross alpha radiation was used in the surveillance program. This policy was followed because of the proximity of the gross alpha detection limit to the PHS Standard. Radiological activity, identified by flags in Table 3, appears to vary with geographic location; a majority of radiation flags tag water sources in the western part of the US. These radiation
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flags were generated from gross alpha and beta screening determinations; no results for tritium were found to exceed the respective health-reference limit. Confirmatory analyses for radium-226 identified three groundwater sources as exceeding the health-reference limit. One source was found to contain radium-226 activities averaging 30 pCi/L; this high activity was attributed to natural activity and use of the source for human consumption was discontinued. The two other sources are currently being investigated. Confirmatory analysds of those samples that exceeded the gross beta health limit did not identify any sources that exceed the health limit for strontium-90. This apparent discrepancy is explained by the fact that gross alpha and beta measurements are screening procedures and radiation from all alpha and beta emitters is counted. Radioactive isotopes of thorium, potassium, rubidium as well as strontium-90, radium-226 and their daughter products can contribute to gross alpha and beta activity. The annual percentages of radiation flags to total number of sources ranged from 13-22%. This annual fluctuation for gross measurements can be attributed to variations in the number and location of water sources sampled each year, and also to the fact that so many different isotopes contribute to gross activity. Of the metals considered to be medically significant, flags were obtained for mercury, chromium, lead, cadmium, silver, barium, and arsenic. The annual percentages of metal flags to total samples ranged from 30% in 1972 to 3 % in 1976. At the time of sample analyses the flagged results were Validated by use of controls; however, upon recollection and an-
layses none of the flagged metals was found to exceed health levels and, in most cases, no metals were detected. Although the flagged data could indicate the transient existence of medically significant metals in a drinking water source, it is generally believed that the flagged results are due to contamination of samples. As these metals are sought at trace levels (0.2-50 ppb), contamination is a constant threat. A small number of flags were obtained each year for nitrate measurements. Nitrate levels (10-15 mg/L) exceedingthe health limit were confirmed for two drinking water sources. Use of these sources for human consumption has been discontinued. Recollection values for the other flags were below the health limit for nitrate, indicating either a transient existence of high nitrate levels or contamination. Flags tagging high fluoride concentrations were found to be valid upon recollection and analysis. These results were attributed to high natural fluoride levels and the water sources are being treated with defluoridizers or personnel exposure to the source is being limited. A small number of water sources were found to contain detectable pesticide concentrations. However, no pesticide concentrations were found to exceed the health limits Additional reading Handbook for Analytical Quality Control in Water and Wastewater Laboratories, National Environmental Research Center, U.S. Environmental Protection Agency, Cincinnati, Ohio, June 1972. Industrial Hygiene Sewice Laboratory Quality Control Manual, Technical Report No. 78, National Institute for Occupational Safety and Health, 1975. Manual of Methods far Chemical Analysis of Water and Wastes. National Environmental ResearchCenter, U.S. EnvironmentalProtection Agency, Cincinnati, Ohio, EPA-62526-74-003, 1974. Standard Methoos for Examination 01 Wafer and Wastewater. APHA. AWWA. WPCF. Washington. D C , 14th edition. 1976
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Paul V. Sneeringer is chief of the Analytical Reference and Quality Assurance Division at the U.S. Army Environmental Hygiene Agency. Dr. Sneeringer is also responsible for maintaining quality assurance in clinical chemistrv. hematoloav. toxicology, industrial hygiene and pollution chemistry, and pesticide chemistry.
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Frederic Belkin is currently an analytical quality-assurance chemist at the U.S. Army EnvironmentalHygiene Agency. In this capacity he has been involved in air and water analyses.
Nicholas Straflon is a quality-assurance chemist at the U S . Army Environmental Hygiene Agency. in this capacity he has been involved in metals and general analyses of water.
Sandra A. Costick is a quality-assurance physical science technician with the U.S. Army Environmental Hygiene Agency. She processes the water samples, collates the analvtical data, and coordinates ::. with data processing for computer printouts of results. Coordinated by LRE
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