ES&T OUTLOOK
Biological monitoring The results of a such a monitoring program can can be interpreted using an individual, medical approach or a group, industrial hygiene approach
Every day, many workers are exposed to a number of chemicals. Prolonged exposure to low-level concentrations of chemical substances is by far the most common risk to which workers are exposed today. Chemicals are inhaled by workers; they are absorbed through the skin or the gastrointestinal tract, and workers may be constantly exposed to a low-level concentration of a chemical. Their body systems can absorb chemicals, transform them to metabolites, distribute the chemicals or metabolites throughout the body, concentrate them in a particular organ, and excrete them. Biological monitoring—the routine analysis of human tissues or excreta for direct or indirect evidence of exposure to chemical substances—is being used to learn more about early detection of health impairment due to industrial chemicals. The types of analyses include the following measurements: • the concentration of the chemical in various biological media such as blood, urine, and expired air, • the concentration of metabolites of the individual chemical in the same media, and • determination of nonadverse biological changes resulting from the reaction of the organism to exposure. 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, so that such exposure does not involve an unacceptable health risk. It considers routes other than absorption by the lungs and is a good method for evaluating individual exposures. For a long time, air monitoring constituted the major means of assessing workers' exposure to chemicals in in188A
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dustry. But this monitoring considers only exposure by the pulmonary route and, even for chemicals that enter the organism mainly through inspired air, it does not indicate the true uptake by the exposed worker. In the introduction to "Industrial Chemical Exposure: Guidelines for Biological Monitoring," an excellent book on biological monitoring published last year, Robert R. Lauwerys of the University of Lou vain (Belgium) pointed out that "even if strict personal hygiene measures can be implemented so that the pollution can enter the organism only by inhalation, there is no reason to postulate the existence of a relationship between the airborne concentration and the amount absorbed." H e also explains that "biological monitoring of worker exposure to industrial chemicals means evaluation of the internal exposure of the organism to a chemical agent, in other words, the internal dose by a biological method, internal exposure and internal dose." Before Lauwerys's book, the data on biological monitoring were scattered in various scientific journals; his work brings together in one volume the tests presently available in this field. Lauwerys divides the chemicals into two groups. A first group contains those chemicals for which there is a strong indication that a biological monitoring method may be useful for detecting an excessive internal dose or body burden; it contains 13 inorganic and organometallic chemicals and 58 organic chemicals, among them carbon monoxide and cyanide. A second list contains 14 chemicals (or groups of chemicals) for which additional data are required to determine the usefulness of the suggested biological monitoring methods.
Thus, biological monitormg indicates an internal dose and a better estimate of risk than ambient-air monitoring. But it must be remembered that reliable biological monitoring is only possible when sufficient toxicological information has been gathered on the mechanism of action and on the fate in the body of the chemicals to which workers may be exposed. Recent symposium The potential of biological monitoring was addressed in a symposium organized by Matt H. Ho (University of Alabama, Birmingham) and H. Kenneth Dillon (Southern Research Institute). The symposium was sponsored by the A C S Division of Chemical Health and Safety and the Division of Small Chemical Businesses. The first international two-day symposium on this field was presented at the Spring A C S meeting in St. Louis. This symposium reviewed the topic of organic chemicals. Another one will be presented at next year's Spring A C S meeting in Miami, Fla. It will review the topic of metals and inorganic chemicals. Speakers from foreign countries including Belgium, Czechoslovakia, France, Germany, Italy, India, and the Netherlands appeared at the St. Louis meeting. The scientists reported on some of the biological-monitoring research activities around the world. Dr. Alfred Bernard of the University of Louvain, who was the keynote speaker, said that the greatest advantage of biological monitoring is the fact that the biological parameter of exposure is usually more directly related to the adverse health effects that are to be prevented than it is to any environmental measurement. There-
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fore, it offers a better estimate of risk than ambient monitoring does. Recent research findings attest to the usefulness of biological monitor ing. Although methods are available for only a limited number of chemi cals today, the number of approved techniques is growing, especially be cause of the following factors: • A global biological monitoring program has been established as part of the World Health Organization and the United Nations Environment Programme. • A relatively new committee of the American Public Health Associ ation ( Α Ρ Η Λ ) is producing a " M a n ual of Biologic Monitoring Methods." • E D C I N , the European Data Bank on Environmental Chemicals, is operating. EDCIN is concerned with occupational health and safety relat ed to evaluation of chemical risk. The risk is related to such factors as time of exposure, toxicity of the material, and metabolism of the chemical. • C E F I C , the Council of Euro p e a n F e d e r a t i o n s of I n d u s t r i a l Chemicals recently began its second action program of the European Eco nomic Commission on Health and Safety at Work, which has a compo nent for biological monitoring; Part 11 of the C E F I C report, "Occupational Exposure Limits and Monitoring S t r a t e g y , " was published in June 1983. Typical research findings A number of specific papers de scribing new findings in this growing field of biological monitoring were presented at the A C S symposium. One goal of these investigations was to correlate internal dose with expo sure data. Urinary S-phenylmercapturic acid and phenylguanine are more useful indicators of exposure to benzene than are the phenolic derivatives, ac cording to the report of G. Miiller of the Institute for Hygiene and Work Medicine (Essen, Federal Republic of Germany). He reported a correlation between concentrations of benzene in air and the excretion of these metabo lites in the urine. Hippuric acid is the metabolite found in the urine of workers exposed to toluene, according to the report of L. K. Lowry of the National Institute for Occupational Safety and Health ( N I O S H ) in Cincinnati, Ohio. He concluded that this metabolite, which was found in urine samples collected from workers at the end of a shift, was a useful indicator of toluene air con centrations exceeding 50 ppm.
The first study of the correlation between occupational airborne expo sure to pentachlorophenol (PCP) and the measurement of urinary concen tration of PCP in which dermal expo sure to PCP could be entirely ex cluded was reported by Jon Rosen berg of the California Health Service (Berkeley, Calif.). Occupational exposure to 1,1,1trichloroethane can be documented by measuring the concentration of the compound in the blood and exhaled air and the urinary excretion of tri c h l o r o a c e t i c acid and t r i c h l o r o ethanol, according to A. C. Monster oftheCoronel Laboratory, Faculty of Medicine at the University of Am sterdam, The Netherlands. He re ported that the best parameter for es timating the time-weighted average exposure over the whole workweek appears to be the concentration of both 1,1,1-trichloroethanc and tri chloroacetic acid in blood 1 5-30 min utes after the last shift of the work week. For noninvasive methods, the best parameter is trichloroethanol in urine on the Monday morning after the workweek. The measurement of the urinary metabolite, 2,5-hexancdione, is the most reliable indicator for worker ex posure to "technical hexane," a mix ture of four compounds, according to the report of F. Brugnone, of the
Medical Institute of Verona, Italy. He said that individually and, on the whole, the «-hexane metabolite, 2,5hexanedionc, was highly correlated with environmental exposure. R. J. Prévost of Southwest Research Institute (San Antonio, Tex.) told how such monitoring can be used under practical conditions to better define occupational hazards. He was interested in the dermal and inhalation routes of chemicals among persons in the U.S. Coast Guard. Some 600 compounds are carried in marine t r a n s p o r t , and m a r i n e t r a n s p o r t workers can be exposed to these compounds when cleaning and flushing tanks and when they fail to wear protective clothing. It is estimated that 100 0 0 0 - 2 0 0 000 workers are involved in one or more aspects of marine occupation; a large majority of these workers are on barges. In addition, between 10 000 and 20 000 workers would be exposed on very large carriers. In some cases, the exposure is in excess of the threshold limit value (TLV). Examples include toluene at 199 ppm for 55 minutes and methanol at 850 ppm for 30 minutes, the latter being about two times the TLV. Urinary samples were favored; the use of blood samples from those workers engaged in marine operations was not recommended. The maximum allowable concen-
Pathway of a chemical from the environment to the target molecules in the organism I Chemical] in — Air — Water — Food
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Ambient Monitoring
Absorption
Distribution • Excretion
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Biological monitoring of exposure
Biotransformation Binding to noncritical sites Nonadverse effects Binding to critical sites Adverse effects Preclinical lesions
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Health Surveillance (Bio monitoring of effects)
Clinical lesions Source: A Bernard and R Lauwerys. General Principles of Biological Monitoring of Exposure lo Organic Chemicals Keynote address at ACS Meeting. St Louis. Mo. April 8-13. 1984
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tration of DMF (dimethylformamide), a widely used industrial sol vent, varies from country to country, from a low airborne concentration of 10 mg/m 3 in the U.S.S.R. to a high airborne concentration of 60 mg/m 3 in Germany; the U.S. value is inter mediate, at 30 mg/m 3 or 10 ppm. The percutaneous absorption of DMF is more important than the pulmonary uptake, according to the report of Z. Bardodej of the Charles University Medical Faculty of Hygiene (Prague, Czechoslovakia). The relationship between the urinary concentration of mercapturates (y) and monomethyl
formamide (x) was y = 4.93 + 0.58.x; the correlation coefficient is 0.92. The best monitoring technique is to mea sure urinary monomethylformamide. More on biological monitoring The proceedings of a symposium sponsored by the Division of Pesticide Chemistry, "Risk Determination for Agricultural Workers from Dermal Exposure to Pesticides," will be pub lished by ACS Books in its sympo sium series. There will be a conference July ΙΟ Ι 3 on "Medical Screening and Bio-
logical Monitoring for the Effects of Exposure in the Workplace" in Cin cinnati, Ohio. This conference is sponsored by the three federal agen cies—NIOSH, EPA, and the Nation al Cancer Institute. —Stanton Miller Additional Reading Baselt, Randall C. "Biological Monitoring Methods for Industrial Chemicals"; Bio medical Publications: Davis, Calif., 1980. Lauwerys, Robert R. "Industrial Chemical Ex posure: Guidelines for Biological Monitor ing"; Biomedical Publications: Davis, Calif., 1983.
Water cleanup trends Additional pretreatment regulations and the enforcement of EPA's new toxics control policy may be expected
In March, industries and others concerned with or affected by water laws and regulations were asking these questions: "Will the Clean Wa ter Act (CWA) be reauthorized this year?" "With or without a new law, what might the regulatory emphasis be in the months and years to come?" As far as the first question is con cerned, EPA's leadership is "desir ous" of early reauthorization. This is according to Jack Ravan, assistant administrator for water, who spoke at the 1984 Water and Wastewater Equipment Manufacturers Associ ation Washington Forum in late Feb ruary. And Sen. Robert Stafford (R.Vt.), chairman of the Senate En vironment and Public Works Com mittee, expressed confidence that two reauthorization bills (S. 431 and 2006—the latter addresses nonpoint sources) would reach the Senate floor this year. In late March Robert Hur190A
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ley of that committee's professional staff offered a similar prediction to the 18th Annual Government Affairs Seminar of the Water Pollution Con trol Federation (WPCF), held in Washington, D.C. On the other hand, many in the water-wastewater com munity—perhaps a majority—do not expect reauthorization this year. Main endeavors With or without CWA reauthori zation, the development of regula tions will continue. The principal en deavors spelled out by EPA Admin istrator William Ruckelshaus for the WPCF seminar are completing the issuance of best available technology economically achievable (BATEA or BAT) rules for direct and indirect in dustrial dischargers; pretreatment of industrial wastewater destined for publicly owned treatment works (POTW); and improvement of the
quality of water not meeting ambient standards despite the installation of BAT. The present water law calls for the use of BAT to begin by July 1. However, EPA is more than 18 months away from completing the is suance of effluent guidelines and im plementing permits. So Ruckelshaus has proposed an extension to July 1, 1988. "We do a disservice by setting deadlines impossible to achieve," he said. Other thrusts could involve in creasing municipal compliance and trying to attack pollution from nonpoint sources. S. 431 and its House companion bill, H.R. 3282, set July 1987 deadlines for these measures. Pretreatment-POTW efforts will involve enforcement of those effluent guidelines already issued and "an ag gressive move" on sludge, Ruckels haus noted, adding that a sludge task force has been established within EPA. Also, because the compliance
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