United States Environmental Protection Agency Office of Health and Environmental Assessment Washington DC 20460 Research and Development EPA/600/S8-85/020 Aug. 1986 s>EPA Project Summary Evaluation of Methods for Analysis of Human Fat, Skin, Nails, Hair, Blood, Urine and Breath L Sheldon, M. Umana, J. Bursey, W. Gutknecht, R. Handy, P. Hyldburg, L Michael, A. Moseley, J. Raymer, D. Smith, C. Sparacino, and M. Warner This research program surveyed and evaluated the methods and procedures used to identify and quantitate chemi- cal constituents in human tissues and fluids including fat, skin, nails, hair, blood, urine, and breath. These meth- ods have been evaluated to determine their ease and rapidity, as well as cost, accuracy, and precision. During this evaluation, a second goal was to deter- mine the feasibility of correlating a pre- ferred method with a specific tissue/ fluid and with easily identifiable chemical and physical characteristics of the analyte. Because of these goals, the search strategy, as well as the literature evalu- ation focussed on analytical methods. The literature search was restricted to lists of chemicals of current interest to the U.S. Environmental Protection Agency, to references cited in "Chemicals Identified in Human Biolog- ical Media, A Data Base," and the "Chemical Abstracts Data Base." The information retrieved was summarized and classified by sampling and analysis methodology. This Project Summary was devel- oped by EPA's Office of Health and En- vironmental Assessment, Washington, DC, to announce key findings of the re- search project that is fully documented in two separate reports (see Project Re- port ordering information at back). Introduction For a long time, air monitoring consti- tuted the major means of assessing workers' exposure to chemicals in in- dustry. But this monitoring takes into account only exposure via the pul- monary route and, even for respirable chemicals, it does not indicate the ac- tual uptake by the exposed worker. Biological monitoring, the routine analysis of human tissues or excreta for direct or indirect evidence of exposure to chemical substances, has also been used to learn more about early detec- tion of health impairment due to indus- trial chemicals. The types of analyses include the following measurements: • concentration of the chemical in various biological media such as blood, urine, tissue and hair; • concentration of metabolites of the original chemical in the same me- dia; and • determination of adverse/nonad- verse biological changes of the or- ganism resulting from exposure to reaction of the organism to expo- sure. Hence, biological monitoring is used in the assessment of human exposure. A main goal of such monitoring is to ensure that the current or past levels of worker exposure are safe. Biological monitoring is being applied increas- ------- ingly to the assessment of exposure in environmentally exposed nonworker populations. The purpose of this research program was to survey and evaluate the methods and procedures used to identify and quantitate chemical constituents in hu- man tissues and fluids including fat, skin, nails, hair, blood, urine, and breath. These methods have been eval- uated to determine their ease and rapid- ity, as well as cost, accuracy, and preci- sion. During this evaluation, a second goal was to determine the feasibility of correlating a preferred method with a specific tissue/fluid and with easily identifiable chemical characteristics, such as octanol-water partition coeffi- cient, water solubility, vapor pressure, etc. Because of these goals, the search strategy and the literature evaluation fo- cussed on analytical methods. The liter- ature search was restricted to lists of chemicals of current interest to the U.S. Environmental Protection Agency (EPA), to references cited in "Chemicals Identified in Human Biological Media, A Date Base" up to 1982 and the "Chemical Abstracts Data Base." The Chemical Abstracts Data Base covers the complete chemical literature from 1967 to present, however, the search performed for this review was restricted to 1976 to 1983. The list of target chemicals included in this review was compiled from a set of five documents received from the EPA Technical Project Monitor. The doc- uments contained lists of compounds of interest to the EPA. The chemicals were classified into a hierarchial scheme based on their phys- ical and chemical properties. This scheme first separated inorganic from organic compounds. Organic chemicals were then separated according to func- tional group substituents. Functional groups that have the greatest effect on a compound's physical and chemical properties and/or analytical behavior are placed highest in the scheme. For example, carboxylic acids are ranked above acid esters. The acid moiety is a stronger functional group with a greater influence on aqueous solubility, boiling point, extraction behavior, and chro- matographic properties. If a compound contains more than one functional group, it is placed in the highest chemi- cal classification. Because this classifi- cation is based on the physical/chemical properties, it should reflect analytical behavior of many of the compounds to aid in the overall evaluation process. Information from the data base "Chemicals Identified in Human Biolog- ical Media" on (1) literature referenced, (2) chemicals analyzed, (3) biological matrix, and (4) analytical technique was entered and stored on computer files. These data were retrieved according to analytical method. Under each analyti- cal method, citations referring to that method were listed according to chemi- cal class, specific chemical, and biologi- cal matrix. The "Chemical Abstract Data Base" was searched using the selected compounds which were cross- referenced by CAS number with the human biological matrices of interest. This information was used for sorting retrieved literature citations and dis- seminating articles to members of the advisory committee who were respon- sible for the preparation of this review. This information was also used to match analytes with biological matrix in order to determine the feasibility of cor- relating analytical method with biologi- cal matrix and with chemical character- istics. Relevant articles which report the use of an analytical technique to measure any of the target chemicals in the seven biological matrices of interest were ob- tained. Only those analytical methods which had at least three articles cited v jie included in the review. During acquisition of literature cita- tions, more than 95% of all citations identified as relevant, i.e., those which reported measuring any of the target chemicals in the seven biological ma- trices, were retrieved. Missing citations were not retrieved for several reasons: • the article was in a foreign lan- guage which could not be trans- lated easily; • the reference in the data base was incorrect; or • a source of the article could not be located. The full report was written to evaluate each analytical method. The evaluation for each method included sections on instrumentation and sample prepara- tion methods. Much of the information on analytical instrumentation was taken from review articles, reference texts, or our working knowledge of the tech- niques. Information on sample prepara- tion methods were generally restricted to the citations in the data bases. The section on method/analyte correlation parameters attempted to suggest physi- cal or chemical properties of analytes which could be used to predict the ap- plicability of the given method to the analysis of that chemical in a specific biological matrix. Conclusions Methods and procedures that were cited in both data bases for the identifi- cation and quantitation of the target chemicals in the seven human biologi- cal matrices were summarized. Broad generalizations are difficult to formulate due to the number of compounds, com- plexity of matrices, and the variety ol methods reviewed. A noncritical survey of the analytes for each method in the data base with a brief summary of the advantages and disadvantages of each of the methods reviewed follows. Atomic Absorption Spec- trophotometry Atomic absorption spectrophotome- try has been the method of choice foi many investigators who require c highly specific, low cost technique foi elemental analysis with ultratrace de tection limits. The advantages of this single-element method have beer known for the past 15 years, but the use of modern instrumentation has pro duced analytical data of greater repro ducibility and has resulted in increasec sample throughput. One of the best documented environmental measure ments (lead in whole blood) is usualh performed by atomic absorptior methods. The biggest disadvantage of this tech nique is not the inherent limitations o the method with respect to analyt specificity and sensitivity, but problem with matrix effects. A variety of diges tion conditions have been developei which in combination with deuteriur background correction and/o chelation-extraction, such as APDC MIBK, have been successful in reducin matrix effects and form the basis fc most atomic absorption procedures. Neutron Activation Analysis (NAA) Neutron activation allows multiel ment analyses on a single sample wit' out pretreatment. Under conditions < high neutron flux, maximum samp size (approximately 1 g) and no interfe ences, NAA provides detection limi which can only be matched by flam less atomic absorption spectrophot ------- metry. Essentially all of the elements of environmental interest (with the excep- tion of beryllium and lead) from nitro- gen to the heavy elements can be ana- lyzed simultaneously by this technique. The principal limiting factor in neu- tron activation analyses is the presence of interferences that result in the gamma-ray signal from the various sources not being resolved. Detection limits may increase by several orders of magnitude when interferences are present. Poorer precision and accuracy also result. Accessibility to a neutron source notwithstanding, NAA can be relatively simple and inexpensive with the capa- bility of measuring a large number of elements simultaneously. When either chemical methods or extensive time resolution is required to minimize inter- ferences; the cost, time, and labor re- quired for analysis increase signifi- cantly. Electrochemical Methods The facility of ion selective poten- tiometry in the analysis of inorganic ions is a distinct advantage of this ana- lytical technique. Although limits of de- tection are typically 10~6 M, which is somewhat higher than competing tech- niques, fluoride and cyanide selective electrodes have been quite successfully used in the analysis of blood and urine. Their simplicity in this regard makes them highly recommended. Anodic stripping voltammetry (ASV) has been applied to the analysis of blood, urine, and hair for a large num- ber of metals including zinc, cadmium, lead, chromium, and copper. Since ASV is capable of differentiating between labile and nonlabile metal species, it is clearly the method of choice when infor- mation regarding metal speciation is desirable. When total metal determina- tions are needed, ASV is comparable to other methods with respect to labor re- quired and accuracy. Cyclic voltammetry has been applied to several metal determinations and, in addition, some organic compounds such as p-amino-diphenylamine. Cyclic voltammetry is an easy technique to im- plement and the analysis is fast; blood samples have been analyzed without further treatment. The equipment cost is relatively inexpensive compared to other instruments used in the simulta- neous determination of metals. The limit of detection (LOD) is higher than for ASV. Emission Spectroscopy A large number of metals may be de- termined using emission spectroscopy. The limit of detection for these metals is adequate for environmental trace analy- sis, and many published data were found on the use of either DC or argon plasma ionization methods. However, by far, the most widely used technique is atomic absorption (AA) spectroscopy. Because of the wealth of data on method performance and the availabil- ity of instrumentation, AA would be considered the method of first choice, but ICP may be faster, more accurate, more precise and have lower LOD. Proton Induced X-Ray Emission (PIXE) Proton induced X-ray analysis may be used for multielement analysis of a large number of samples. Although bio- logical samples can be analyzed in a variety of forms, including untreated specimens, best results are achieved by digesting the organic material and plac- ing the resulting solution on a Mylar film for irradiation. The elements nor- mally measured for PIXE range from phosphorous (2= 15) to lead (2 = 82) with limits of detection at the sub- nanogram level. The method is simple, allows high sample throughput, and is currently be- ing performed inexpensively by several laboratories. Spectrophotometry (Colorime- try) Spectrophotometry has the advan- tage of being a simple and quick proce- dure utilizing instrumentation which is widely available and relatively inexpen- sive. It is capable of determining com- pounds and metal complexes at the low microgram to high nanogram range with good precision (2-3%). The disad- vantages of this technique are the labor intensive sample preparation steps, and the nonunique nature of the measured signal (compared to AA/ICP). This method is suitable for many analytical measurements, particularly where the operating laboratory does not have AA/ ICP spectrometers. When available, AA or ICAP would usually be the methods of choice. Gas Chromatography Gas Chromatography is used for the separation and determination of volatile or semivolatile organic compounds. Re- cent developments in capillary column Chromatography provide for very high resolution to give separation of com- plex samples. The use of specific column packings allows the determina- tion of polar and some compounds with low volatility. Effluent from the GC column may be analyzed using a specific (e.g., electron capture, nitrogen/phosphorus) or a non- specific (e.g., flame ionization, thermal conductivity) detector. Limits of detec- tion range from subpicogram to micro- gram depending upon the detector used and the compounds determined. Gas Chromatography is a simple tech- nique for the determination of organic compounds and is used extensively on human biological extracts. Compounds which are nonvolatile (B.P. >300°C), very polar, or heat labile cannot be de- termined directly by this method. For these compounds, high performance liquid Chromatography is generally used. Some polar and/or nonvolatile compounds may be derivatized to im- prove gas chromatographic perform- ance. Most biological samples cannot be analyzed directly. Analytes are usually extracted and fractionated prior to anal- ysis. Although GC analysis itself is a simple rapid procedure, sample prepa- ration techniques are often complicated and time-consuming. Mass Spectrometry Mass spectrometry is a sensitive, specific but expensive technique. The various forms of mass spectrometry that can be employed complicate the question of when the technique should be used. Spark source mass spectrome- try is extremely valuable in elemental analysis. Atomic absorption spec- trophotometers and inductively cou- pled argon plasma spectrometers are substantially less expensive for these analyses; however, for a semiquantita- tive scan of a broad range of elements, spark source mass spectrometry could be the method of choice. Many com- mercial laboratories offer spark source mass spectrometric assays as a service, so purchase would not be necessary for an occasional need. The main use of mass spectroscopy is in the identifica- tion and quantitation of organic com- pounds. Isotope ratio mass spectrometry is the preferred method for accurate de- termination of isotope ratios. If such an assay is required, specialized laborato- ries make effective use of the instru- mentation. ------- Although gas chromatography/mass spectrometry as a combined technique is one of the most widely used analyti- cal methods, the decision to use the technique should be evaluated care- fully. Gas chromatography is far more cost-effective and is usually more sensi- tive. However, the analysis of biological samples for various organic con- stituents by gas chromatography pre- sents various difficulties which may re- quire the specificity inherent in the mass spectrometric technique. For ex- ample, if identification of a pesticide is desired for forensic or regulatory pur- poses, the use of gas chromatography/ mass spectrometry with authentic standards will give the needed informa- tion. Biological samples often contain material which coelutes with a com- pound of interest and only the specificity of the mass spectrometric technique will give a successful assay. When standards for the compounds of interest are not available, identification can be carried out with a high degree of confidence only by the mass spectro- metric technique. In summary, mass spectrometry should be used when its specificity is required, a less expensive technique is not adequate, or when certain types of information are available from no other source, for example, accurate isotope ratios or accurate mass measurement. X-Ray Spectroscopy X-ray emission spectroscopy can be used in chemical analysis for both quan- titative and qualitative studies. X-ray spectroscopy is applicable to the deter- mination of most metals in multiele- ment analysis. The technique is expen- sive and not widely available. Nuclear Magnetic Resonance (NMR) Nuclear magnetic resonance spec- troscopy is applicable to a wide range of organic compounds, provides informa- tion on chemical structure, and can be quantified. The operation of NMR in- struments is rather complex; however, no significant sample preparation is re- quired. The equipment is very expen- sive and not widely available. Thin Layer Chromatography Thin layer chromatography is a sepa- ration technique based on an adsorp- tion or partition process and employs a thin, flat bed of sorbent. Thin layer chro- matography can be used for the separa- tion and semi-quantitation of complex mixtures and has. proven useful as a cleanup technique for analvtes present in biological fluid extracts and environ- mental samples. With the exception of some macro- molecules, reactive compounds, and volatile substances; virtually any or- ganic compound and many.inorganic ions can be detected by thin layer chro- matography. The limit of detection is a function of the specific .detection sys- tem utilized. Semi-quantitative thin layer chromatography is fast, simple and can be accomplished with a mini- mum of expensive equipment. Quanti- tative thin layer chromatography with modern instrumental detection systems is both accurate and sensitive but re- quires rather expensive equipment. High Performance Liquid Chro- matography High performance liquid chromatog- raphy is a simple and standard separa- tion technique applicable to virtually any mixture of organic compounds as well as certain ionic species. It is usually applied to complex matrices for which gas chromatography is not usable, such as matrices containing high boiling point chemicals or compounds which decompose under GC conditions. A wide variety of detectors can be inter- faced to a liquid chromatography column such as ultraviolet detectors, re- fractive index and fluorimetric detec- tors. Miscellaneous Methods During this survey, two reports were found dealing with the determination of compounds of interest using some mis- cellaneous methods. The scarcity of publications did not warrant a special section for these techniques in this re- view. One such report describes the evalua- tion of the permeability of phenolic compounds through human stratum corneum using a desorption technique. In another report, laser microprobe mass analysis (LAMMA) is used to de- termine metal ions and organic com- pounds in solid samples which require spacial resolution. Methods for Breath Analysis Several combinations of sampling, concentration, and analysis methods were cited in the reviewed literature for the identification and quantitation of target compounds in human breath. A brief noncritical review of the advan- tages and disadvantages of each method follows. In 1977 an international workshop or "The Use of Biological Specimens foi the Assessment of Human Exposure tc Environmental Pollutants" summarizec the data on the location or compartmen talization of xenobiotics and/or thei metabolites in various biological ma trices including breath. They concludec breath is not useful to evaluate expo sure to arsenic, beryllium, cadmium chromium, fluorine, lead, mercury molybdenum, manganese, nickel, vana dium, zinc, copper, cobalt, platinum palladium, tin, methyl mercury, DDT phenoxy herbicides, pentachlorophe nol, PCB, PBB, PCN, tetrachloro dibenzo-p-dioxins, benzofuran, azoben zene, polycyclic hydrocarbons, amini and nitro derivatives, organophospho rus esters, cyanides, nitriles, mycotox ins, antibiotics, and hormonal sub stances. They concluded breath level: correlate with body burden in the case: of chlorinated solvents, plasti monomers, fluorinated propellants nonsubstituted aliphatic and aromati volatile hydrocarbons, alcohols, ethers ketones, and carbon monoxide. It wa also concluded selenium breath level could possibly be useful as an indicate specimen but further research was re quired to confirm selenium. Apnea Direct Injection/Gas Chromatography The apnea sampling method con bined with direct injection of the expire air into a gas chromatograph is an ei tremely simple and fast method whic requires no specialized equipmen Since no concentration is achieve! however, the limit of detection is reli lively high for this method. Breathing Valve/Direct Injec- tion/Gas Chromatography This method, like the apnea/direct it jection/GC method, is simple and fast. breathing valve, air tank, and sampl collection bag are required making slightly more complicated than the a| nea method. Again, the sample is ni concentrated before injection into tr gas chromatograph, resulting in red lively high limits of detection. Becaus very little sample manipulation is pe formed, recoveries are high. Specific r covery values were not found in the li erature reviewed. ------- Breathing Valve/Adsorbent Concentration/Gas Chromatog- raphy This method is complicated and ex- pensive compared to the direct injection techniques. The concentration achieved, however, results in very low detection limits (as low as 1 part per trillion). This allows a much larger num- ber of trace components to be identified and quantitated, but also leads to more problems with background interfer- ences. Some reported recoveries are high, better than 95%, with coefficients of variation of 3-6%. Cryogenic Trapping/Gas Chro- matography This method concentrates the com- pounds of interest without concentrat- ing the oxygen and nitrogen matrix. The extended sampling period (60 minutes) results in the equivalent of sub-ppb de- tection limits although contaminants in the supply air could increase the limit of detection for those compounds. The cryogenic trapping method is sensitive but also complicated, time-consuming, and requires a specialized cryogenic trapping system. No recovery data are available for this method. Tenax GC Cartridge/GC/Mass Spectrometry This method concentrates the com- pounds of interest by directly adsorbing the breath or breath collected in a Ted- lar bag onto a Tenax cartridge. The Tenax cartridge is later thermally de- sorbed and injected into a GC/mass spectrometer. This method has excel- lent sensitivity but it is costly and re- quires elaborate equipment. The per- cent recovery for laboratory samples ranges from 77 to 110 percent. Cascade Impactor Sampling/ Photon Induced X-Ray Emis- sion (PIXE) Analysis This is a sensitive but very compli- cated method for elemental analysis of breath. Exhaled air (4-6 L) is concen- trated for PIXE analysis using a cascade impactor which results in detection lim- its at the nanogram level. Sample col- lection efficiency is high (85-99%) which should lead to high recoveries. The dis- advantage of this technique is that a large amount of specialized and expen- sive equipment is required including cascade impactors, a computer for spectral analysis, and a Van de Graff ac- celerator for PIXE analysis. Recommendations The goal of this research program was to evaluate methodologies for de- termining chemicals of interest to EPA in human biological matrices. This re- view included the citations listed in "Chemicals Identified in Human Biolog- ical Matrices, A Data Base" and the Chemical Abstracts Data Base. Based on this extensive literature, summary reviews have been compiled according to methodology and form the bulk of the full report. In addition, based on the chemical and physical characteristics of the com- pounds of interest and the method by which they are determined, some sim- ple and expected correlations can be found. Some general recommendations can be summarized as follows: 1. Many volatile and semivolatile or- ganic compounds found in human biological matrices can be deter- mined by gas chromatography coupled with a variety of detectors. To select a specific detector, the compound type and the matrix type being analyzed must be taken into account. 2. Organic compounds of high boil- ing point or that decompose under gas chromatographic conditions can be determined by liquid chro- matography coupled with a variety of detectors. Again the selection of a specific detector depends on the compound and matrix type being analyzed. 3. Adsorption onto Tenax cartridges is the most widely used breath sampling method to preconcen- trate organic compounds, includ- ing hydrocarbons, chlorinated hy- drocarbons, alcohols, ketones, nitrogen-containing compounds and others. 4. Most metals and metal-containing compounds can be analyzed by atomic absorption spectroscopy or inductively coupled argon plasma. When the metals are in solid ma- trices such as hair and tissue, they can be determined by neutron acti- vation analysis and proton in- duced X-ray spectroscopy without further sample preparation. Some specific metal matrix combina- tions may be best analyzed by electrochemical methods orcolori- metric methods. Other techniques applicable to the analysis of metals and organometallic compounds were found, however, they do not appear to be as widespread and convenient as the ones mentioned above. With the exception of lithium and beryllium, most metals in breath can be determined by PIXE analytical techniques. Body Burden Biological monitoring of humans for xenobiotic body burden entails the col- lection and analysis of biological speci- mens (organs, tissues, blood, etc.). Biological monitoring is useful for several reasons. First and foremost, it provides direct evidence of exposure and absorption of a xenobiotic. It thus alerts one to the possibility of a human health hazard. The data obtained by bio- logical monitoring can be correlated with the observed level of pollutants in the environment and with the incidence of human diseases, which may be due in part to the presence of the pollutants. These correlations can be used to deter- mine priorities with regard to research relating to human health and to deter- mine the necessity of regulation of pol- lution sources. Biological monitoring can point out pollutant problems which are not otherwise noted, such as could occur due to bioaccumulation of pollu- tants in humans resulting from long- term exposure to very low levels of pol- lutants in the environment. In 1977 an international workshop was held in Luxembourg on "The Use of Biological Specimens for the Assess- ment of Human Exposure to Environ- mental Pollutants." The objectives of the workshop were: (a) To assess the types of environ- mental pollutants and human specimens most suitable for bio- logical monitoring and to evalu- ate the probable usefulness of bi- ological specimen banking. (b) To examine the state of the art and technical feasibility of pro- grams designed to collect human biological specimens for biologi- cal monitoring and biological specimen banking. (c) To develop guidelines on sam- pling, sample preparation, stor- age, and analytical requirements. (d) To make recommendations for further research and develop- ment. Exposure routes for organic chemi- cals are usually inhalation, ingestion, and dermal absorption. Once absorbed, the chemical may be excreted, (includ- ------- ing exhalation) stored, or metabolized. In general, chemicals are metabolized to a more polar form which leads to conjugation and excretion in the urine. The fate of any chemical will depend upon its volatility, polarity, and chemi- cal and biological stability. For example, polychlorinated biphenyls (PCB) and polychlorinated terphenyls (PCT) are nonvolatile, inert, lipophilic compounds which are stored in the adipose tissue. More polar compounds such as phenols and acids are generally excreted in the urine. Several reports found in the pub- lished literature described the simulta- neous analysis of many elements in hu- man biological matrices. Significant differences in the trace levels of chlorine, potassium, calcium, titanium, manganese, iron, copper, and lead in hair from different parts of the body were found. This suggested that the trace elemental absorption and ac- cumulation in hair not only depends on the particular element, but also on the location of the hair in the body. The trace concentrations in white and black hair was also found different. Seventeen different elements were analyzed simultaneously in healthy and pathological tissue to obtain informa- tion on the cancerous process. Signifi- cant differences in the content of vari- ous elements were found in the normal and pathological tissue. Potassium, zinc, and selenium were found in higher concentration in the cancerous mucosa of the stomach. No significant differ- ences appeared in the elemental com- position of blood, erythrocytes, hair, and striated muscle taken from the ab- dominal wall from patients with gall bladder or stomach cancer when com- pared with other noncancer diseases. Human hair root has been analyzed for the presence of several elements. Hair root, rather than strand may reflect the most recent exposure influences and its analysis is exclusive of exter- nally acquired constituents. Samples collected from 23 randomly selected rural Florida children, three to six years of age were analyzed. The results showed differences in the Fe content by sex and Cu (and possibly others) differ- ences caused by intake. Human blood serum was analyzed for zinc, copper, iron, chromium, man- ganese, and selenium as part of a sur- vey to determine whether or not the Australian aboriginal people received optimal diet. Special attention was di- rected to chromium because of the high incidence of diabetes mellitus in this population. Multiple-element analysis of human cerebrospinal fluid and other tissues was used to determine diseases of the nervous system. The distribution of copper, iron, and zinc in the cere- brospinal fluid was such that deficien- cies could not be studied. For the major- ity of trace elements studied, the normal values could not be determined much less the deficiencies. The interpretation of sporadic high levels was not possi- ble. High levels of silicon found were not anticipated. The accumulation of sil- icon in the body fluids of patients with renal failure and on dialysis coupled with the clinical correlations made sili- con a candidate for an uremic neuro- toxin. The higher levels of silicon in cerebrospinal fluid of clinically- diagnosed and autopsy-proven cases of Alzeheimer's disease coupled with the presence of silicon in the neurofibrillary tissue of these patients suggest a corre- lation of silicon levels with this poorly understood disease. Twenty-four elements were mea- sured in hair from 20 individuals who worked in a lead-zinc smelter in Poland. These same elements were also mea- sured in hair taken from 20 individuals considered "normal" or not exposed. Elements found to be at elevated levels relative to the controls included As, Se, Ag, Cd, and Sb. L. Sheldon, M. Umafia. J. Bursey, W. Gutknecht, R. Handy, P. Hyldburg, L Michael, A. Moseley, J. Raymer, D. Smith, C. Sparacino, and M. Warner are with Research Triangle Institute, Research Triangle Park, NC 27711 James Bridges is the EPA Project Officer (see below). The Project Summary covers the following reports: "Evaluation of Methods for Analysis of Human Fat, Skin Nails, Hair, Blood and Urine,"(Order No. PB 85-242 790/AS; Cost: $28.95, subject to change) "Methods for Sampling and Analysis of Breath," (Order No. PB 85-243 277'/AS; Cost: $9.95, subject to change). The above reports will be available only from: National Technical Information Service 5285 Port Royal Road Springfield, VA 22161 Telephone: 703-487-4650 The EPA Project Officer can be contacted at: Hazardous Waste Engineering Research Laboratory U.S. Environmental Protection Agency Cincinnati, OH 45268 ------- United States Environmental Protection Agency Center for Environmental Research Information Cincinnati OH 45268 Official Business Penalty for Private Use $300 EPA/600/S8-85/020 ,S. OFFICIAL. MA8J A PENALTY JBIVATr. r .. _, -. ~~ ,SE S300| -ZQ $ I ~ 00003?? |WVp PROTECTIO ON 5 S OEARSOffW STREET CHICAGO IL 60604 • ------- |