Document KRa447XeKNoJJj5yKjL0j4r80

The fiber that's panicking America Pamela S. Zurer, C&EN Washington March 1984-- The Environmental Protection Agency assesses a $24,000 fine against three schools in Goffstown, N.H., for failing to comply with EPA's rule concerning asbestos in schools. December 1984-- The District of Columbia files a $400 million lawsuit against asbestos manufacturers and distributors to recoup the cost of removing asbestos from city buildings. January 1985--Fairfax County, Virginia, government announces it will spend $5 million to $6 million to remote asbestos from three public buildings, even though it says air levels are not hazardous. Demand for asbestos in the U.S. last year was only about 30% of what it was at its peak in 1973. Fear of the mate rial's toxicity and the health-related lawsuits it has en gendered are largely to blame. But demand has been mushrooming for the services of the asbestos abatement industry, as property owners rush to remove asbestos that was used as fireproofing and insulation in many buildings built before the mid-1970s. Demand for legal expertise is increasing, too, with property damage suits multiplying rapidly. Two decades ago, concerns about asbestos hazards centered on workers who had been exposed to huge amounts of fibers in their jobs. In the 1960s, landmark epidemiological studies by Irving J. Selikoff of Mount Sinai School of Medicine and E. Cuyler Hammond of the American Cancer Society showed that insulation workers who had dealt with asbestos for 20 years or more were dying of cancer and the complications of asbestosis at alarming rates. Later, a few people whose only contact with the material was that they lived in the same house as asbestos workers were found to be dying of meso thelioma--a rare cancer of the lining of the lung or abdomen. In 1971, asbestos became the first material to be reg ulated by the then-new Occupational Safety & Health Administration. In 1982, lawsuits filed by workers suf fering from asbestos-related diseases led Manville Corp.--once the largest U.S. asbestos producer but since 28 March 4.1985 C&EN HWBUI0002843 1983 out of that business--to look for an escape from the rising costs in bankruptcy court. Today, although there is still concern that people who work with asbestos are not protected adequately, fear is mounting over the long-term effects of exposure to as bestos in the general environment. Asbestos fibers can be found in the air almost anywhere if you look hard enough. Sources of asbestos in outdoor air range from natural rock to mining and manufacturing operations to particles released from the brake linings of cars and trucks. Indoors, aging or damaged building materials can release asbestos into the air. Anxiety over asbestos in buildings began to grow in earnest last spring when the Environmental Protection Agency started highly publicized efforts to enforce its asbestos-in-schools rule. That regulation requires school administrators to inspect their buildings for asbestoscontaining materials that crumble easily. If any is found, the schools must notify employees and parents that friable asbestos is present. EPA doesn't require that the material be removed, because the mere presence of as bestos is not necessarily hazardous, but recommends each school be evaluted on a case-by-case basis. Telling parents that there is asbestos in their children's school but authorities aren't going to do anything about it, however, is like saying there's dynamite in the base ment but there's no need to worry because the fuse isn't lit. Many parents have been frightened by statements that breathing a single fiber of asbestos can cause cancer years later. Panic and pressure ensue, and the result in many cases has been school closings and hasty removal of asbestos. Similarly, asbestos is being taken out of many private and public office buildings. Often owners are motivated by fear they will be held liable for future asbestos-related diseases in the buildings' occupants. The bill for all this ripping out of asbestos may come to $20 billion, a staff member of the House Appropriations Committee esti mates. Yet no one is really sure how hazardous low levels of asbestos in the air are. And asbestos removal is a com plicated task that, if done improperly, can leave higher air levels of asbestos in the building than existed before the work started. Evaluating the risks that asbestos poses to the general population requires extrapolating data gathered in the workplace, where approximate fiber levels are known, to a much larger group of people exposed to much lower concentrations that are essentially unknown. Unlike the case with many toxic chemicals, a large amount of in formation on occupational hazards of asbestos is avail able. Even with that massive body of literature, however, it is very difficult to pin down accurately the risks to people who are exposed outside the workplace. For example, last year a National Research Council (NRC) Committee on Nonoccupational Exposure to Asbestiform Fibers tried to quantify the risks of inhaling low levels of asbestos. The panel concluded that breathing the asbestos present in ambient air may be hazardous and some deaths from cancer probably will result. In contrast, a Canadian report by the Royal Commission on Matters of Health & Safety Arising from the Use of Asbestos in Ontario, also issued last year, finds "no evidence that disease afflicts individuals who breathe asbestos in outdoor air or inhale it as occupants of asbestos-containing buildings." Although the NRC panel's stated conclusions are considerably more alarming than those of the Canadian group, the NRC committee states in the body of its report that the number of deaths expected to result from nonoccupational exposures to asbestos are very uncer tain. In fact, in calculating the quantitative risks of de veloping cancer from such exposures to asbestos, the NRC panel estimated the risk could be as high as 1700 per million or could be nil. "You must realize you can't pin down any specific numbers within that range," says committee member Jeremiah Lynch, manager of industrial hygiene for Exxon Chemical. As with all quantitative risk assess ments, so many assumptions were necessary that the panel found it impossible to be exact. Because of the weight a report from the prestigious NRC can carry with policy makers struggling to regulate asbestos, it's important to look at all the ifs, ands, and buts of the study. "A danger we all recognized when we worked on this was that people will overlook all the qualifiers," Lynch says. Risk assessment complications To assess the health risk of a substance, its toxic effects must be identified, the relationship between dose and disease clarified, and the dose the population is exposed to determined. Uncertainties abound at every step. In the case of asbestos, the toxic effects of high expo sures are well documented. Among them are asbestosis, a type of pulmonary fibrosis or scarring of the lungs. Victims become short of breath and may eventually struggle so hard to breathe that they die of heart failure. Asbestosis, which may develop after years of intense U.S. consumption of asbestos peaked in 1973 , Thousands of metric tons a Estimate. Source: Bureau of Mines March 4f 1985 C&EN 29 HWBUI0002844 Special Report What's in a name? Even defining asbestos is difficult Asbestos is not a discrete chemical compound or even a single group of minerals. The term is an imprecise com mercial one that refers to several fibrous inorganic materials that are valued in in dustry for their high tensile strength and resistance to heat. Unfortunately, sometimes minerals that do not meet mineralogists' criteria for asbestos also are lumped under the col lective term. With medical scientists, federal regulators, industrial hygienists, contractors, unions, school boards, and even parent-teacher associations trying to tackle the problem of indoor exposure to asbestos, imprecise definitions only make a complicated problem even more difficult to handle. The several mineral forms that are known commercially as asbestos vary in composition, fiber size, and crystal structure. They share what mineralogists Call the "asbestiform habit"; that is, under certain rare conditions the minerals crystallize in bundles of hundreds or thousands of strong, flexible fibrils that look like organic fibers. However, the same minerals can--indeed usually do--crystallize in nonfibrous, rocklike forms. Other minerals (for example, talc) also may sometimes form fibers under certain geological conditions. These fibers ought not to be called asbestos, mineralogists argue, because they lack the unique flexibility and tensile strength of true as- silicates can crystallize as asbestos fibers ' ClwmtelrotmuU______________AtbtqtomvtMr JjSERPENTINE GROUP----------- ------------------------------- --------------- --------------- i > patefpenUne ' ' - i MgeSUOto(OH)g -c ||uviPHIBOLE GROUP_______________________ % Chrysolite (white) ^,, pRlebeckite . Na2Fe32+Fe23+Sle022(OH,F)2 Crocidolite (blue), gCummlngtonitoIr'gninerite 1 (Mg,Fe2+)7Si022(0H)2 Cummingtontte- ' grunerite asbestos (amoslte, brown) actinollte 'CaJrfMg,Fe*+)6SeOa2(OHh Tremollte-actinollte g^hophyBito , ; Pmwok BMW ofWhM (Mfl.Fe-)7SiflOSa(OH,F)2 Anthophytlite asbestos frJV* v*tr *-,!< % bestos varieties. Asbestos fibers tend to cleave along the long axis of the fiber, yielding the thinner component fibrils, rather than break across the fiber axis into shorter lengths. All commercial varieties of asbestos are silicates, that is, minerals where Si04 tetrahedra form the backbone of the crystal lattice. Silicate minerals are classified according to their crystal structures. Asbestiform mineral varieties occur as members of two groups: the serpentine and amphibole minerals. Only one commercial asbestos min eral, chrysotile, belongs to the serpentine group. Serpentine is a magnesium sili cate, in which layers of linked silica tet rahedra alternate with layers of magne sium oxide-hydroxide octahedra. In ser pentine rock, the double layers result in platy crystals that tend to cleave into sheets like mica. In the asbestiform vari ety, however, the double layer rolls up on itself, curling as it grows to form long hollow tubes that are Characteristic of chrysotile. Chrysotile asbestos also is called white asbestos. Most asbestos being produced today is chrysotile, primarily from Canada and the U.S.S.R. The other types of commercial asbes tos all belong to the amphibole mineral group. Amphiboles are characterized by exposure, was the first toxic effect of asbestos to be un covered. Early occupational standards were designed to protect workers from that disease. "Asbestosis occurs, for all practical purposes, only after exposure in the workplace/' says Arthur M. Langer, a mineralogist who is associate director of the environ mental sciences laboratory in Mount Sinai School of Medicine and a member of the NRC panel. The com mittee did not try to quantify the risk of asbestosis in its report on nonoccupational hazards, as it considered such risks in the general population to be nil. Epidemiological studies have shown that occupational exposure to asbestos also can produce lung cancer, fre quently occurring after a latency period of 10 to 30 years. Hammond and Selikoff documented that smoking cig arettes multiplies the risks of developing lung cancer from asbestos exposure. Lung cancer in asbestos-exposed workers could be cut significantly if they did not smoke cigarettes. Mesothelioma is a very rare, always fated, form of cancer of the lining of the lungs and abdominal cavity. The National Cancer Institute estimates there are only about 970 cases a year in the U.S. It is often called a "marker disease" for asbestos because most cases develop 20 to 40 years after exposure to that material. However, in 10 to 30% of all mesothelioma victims no exposure to asbestos can be documented. Nevertheless, most researchers believe there would be few cases of mesothelioma in the absence of asbestos exposure. Unlike lung cancer, the risk of developing mesothe lioma is not tied to smoking. However, the risk seems to increase with the amount of time that passes after an individual is first exposed. That is what makes parents so fearful for their children's health. For if it takes, say, 40 years to develop mesothelioma, a child exposed to asbestos at age 10 would be more likely to get that cancer before dying of something else than an adult exposed at age 25. Dose-response curves The health risks of breathing high amounts of asbestos fibers are clear. What- is less certain is the relationship between the amount of fiber inhaled and the amount of disease--that is, the dose-response curve. Some occupational studies have complete enough data on dose levels to indicate that the risk of disease drops 30 March 4,1985 C&EN HWBUI0002845 Minerals that under certain geological conditions crystallize as asbestos fibers more often form typical rocks. CummlngtonHe (right) Is the mineral that may sometimes crystallize as asbestos fibers known as amoslte (left) strips of cations (usually calcium, sodium, magnesium, iron, or aluminum) sandwiched between two strips of linked silica tetrahedra. All the amphiboles have about the same basic structure but are substituted with different cations. Amphibole strips of asbestos are thought to grow in single crystal whiskers, often in veins of massive nonfibrous rock. Only two amphiboles have been ex- pioited commercially as asbestos to any significant degree. Crocidolite (blue asbestos), the asbestiform variety of the mineral riebeckfte, currently is mined only in South Africa. Cummingtonite-grunerite asbestos (brown asbestos)--produced only in the Transvaal province of South Africa--is often called amosite from the acronym for the company Asbestos Mines of South Africa. Other amphiboles, such as anthophyllite and the tremollte-actinolite series, also occur in asbestiform varieties, but only rarely. Further complicating matters is that minerals rarely occur as their pure, ideal composition but may contain a wide va riety of contaminant ions. Batches of chrysotile from different mines, for ex ample, are never identical. Mineralogists themselves differ on the details of defining asbestos. But the fine points are even more likely to be ob scured when the term asbestos is used by medical scientists or regulatory agencies. For instance, the legal regulatory defini tion of asbestos created by the Occupa tional Safety & Health Administration in setting occupational exposure limits is broader thqp the definition mineralogists and some other government agencies prefer. OSHA defines the minerals chry sotile, crocidolite, amosite, and all forms of anthophyllite, tremolite, and actinofite as asbestos. "OSHA's terminology is so broad it includes a great deal of Earth's crust," says Malcolm Ross, mineralogist with the U.S. Geological Survey. OSHA is con sidering modifying its definition by adding the word "asbestiform" in front of an thophyllite, tremolite, and actinolite. That would bring OSHA's practice into line with the Mine Safety & Health Administration and the Consumer Product Safety Com mission. with decreasing exposure to asbestos. But there is no evidence in occupational studies to show there is a threshold level below which there are no adverse effects. /The problem is we haven't observed any safe levels," says Langer. Some researchers think there aTe no safe levels of as bestos in the air. "As long as there's arty exposure, there will be illness," says Selikpff. Accordingly, in formu lating its report, the NRC committee chose to make the conservative assumption that no threshold level exists below which there isn't any risk of developing lung cancer or mesothelioma from asbestos. Another problem in establishing a dose-response curve is the inaccuracy of old dose measurements. "We can't even be sure what was in the workplace 30 years ago," Langer says. "We only have good measurements since 1972," when OSHA began requiring them. The shape ef the dose-response curve at low doses isn't known and must be extrapolated from the high occu pational exposures. "When extrapolating down to zero dose you must be careful," Langer says. "You are going beyond the hard data and extrapolating through doses for which no biological data are available." As is often done in estimating the environmental risks of carcinogens, the NRC panel assumed the response was linear. This again is a conservative assumption that tends to overestimate the incidence of cancer at low doses. The most controversial assumption in the NRC report is the panel's decision to lump together all forms of as bestos. The term asbestos is a commercial one that in cludes a number of mineral varieties that crystallize as strong, flexible fibers. A very vocal minority asserts that the type of asbestos most commonly used in the U.S., chrysotile, causes significantly less mesothelioma than other forms of asbestos, known as amphiboles. By grouping all the types together, these critics charge, the overall risks from asbestos are exaggerated. "The [NRC] report is dangerous," says Andrew Churg, a pathologist at the University of British Columbia. "It ignores the difference between chrysotile and the am phiboles so it makes the mesothelioma risk seem much higher." Churg thinks the Canadian report, which dtes only a weak association between chrysotile fibers and mesothelioma, is more accurate. Churg's opinion is shared by others who object to the different species of asbestos being classed together. March 4,1985 C8EN 31 HWBUI0002846 Special Report Malcolm Ross, a mineralogist with the U.S. Geological Churg himself, however, says his data should not be Survey, has made something of a crusade of his belief used to judge the incidence of mesothelioma. "These are that chrysotile is not a significant health threat in a selected autopsies," he says. "You have to conclude that nonoccupational setting. chrysotile ore causes mesthelioma, but it's very dan "When the public is led to believe that only the tiniest gerous to draw conclusions on incidence" because the bit [of asbestos] will kill them, they're going to demand autopsies are not ai representative sample. its removal," Ross says. "I'm troubled about where we Even though there are substantially fewer deaths from are putting our money relative to the risks." mesothelioma tied to chrysotile, the NRC panel decided Ross says that to estimate accurately the health effects not to weigh the risk of the various forms of asbestos of each kind of asbestos separately, epidemiologists must separately. That is largely because, considering smokers look at the experience of asbestos miners and millers. He and nonsmokers together, the most common kind of points specifically to chrysotile miners at Thetford Mines cancer associated with asbestos is lung cancer, and in Quebec. An epidemiological study of about 11,000 chrysotile appears to be just as potent in causing lung miners there by J. Corbett McDonald of McGill Uni tumors as the other types of asbestos. However, the risk versity found very few deaths from mesothelioma. In of lung cancer in nonsmokers, according to the NRC contrast, other studies have shown up to 10% of workers panel, is less than that of mesothelioma. exposed to the amphibole called crocidolite die from "I think that Ross' basic assertion that the amphibole mesothelioma. asbestos minerals produce more mesothelioma is cor The view that chrysotile asbestos is much less haz rect," says committee member Langer. "But that doesn't ardous than the amphiboles forms the basis for regula mean chrysotile is a safe fiber. The lung cancer rate in tion of asbestos in the U.K. and other members of the some industries that dse this fiber is very high. We still European Economic Community, where occupational have to contend with it." standards allow higher levels of chrysotile than the Langer also suggests that different disease rates ex amphiboles. The recent Ontario report recommends perienced by miners as compared to industrial workers banning amphibole asbestos in Ontario, but not chry may be caused by variations in fiber properties. "The sotile. (The Canadian province of Quebec is a major physical dimensions and surface characteristics may vary producer of chrysotile asbestos; Ontario is not.) But in from industry to industry," he says, "and these may be the U.S., Ross' position invites heated reaction. important factors in chrysotile asbestos's differential 'There's not a shred of evidence that some forms are toxicity." The Canadian report also notes differences in less hazardous than others," Selikoff says. He points to disease rates in different industries. a new study by Churg as the "smoking gun" that proves chrysotile is just as deadly as other forms of asbestos Exposure measurements when it comes to mesothelioma. Churg and his co The nature of the fiber is only one factor in gauging workers found that of 90 chrysotile miners autopsied the risk of low-level exposure to asbestos. Just as im between 1980 and 1983, six died of mesothelioma. portant are the intensity and duration of exposure. Measuring the amount of asbestos in ambient air is not a trivial problem, however. Neither is relating ambient a air levels to the amounts of asbestos found in occupa- ! tional settings. | Asbestos levels in the workplace are measured as the | number of fibers in a given volume of air. For instance, I OSHA's permissible exposure limit currently is two fi- bers of asbestos per cubic centimeter of air. 3 OSHA counts the number of fibers more than 5 long and at least three times longer than they are wide, using an optical microscope. Most fibers--perhaps 95%--in an occupational air sample are shorter than 5 pm, but OSHA reasons the longer fibers are a fair index of the entire amount. The light microscopy technique normally used in occupational settings is phase-contrast microscopy. "It allows you to visualize materials with a long aspect ratio (ratio of length to width) that are greater than 0.2 pm in width," says John A. Small, a research chemist with the National Bureau of Standards. "But it doesn't distinguish among fibers of different origins. Under the phase- contrast counting methodology, glass, cellulose, and carbon fibers may be counted as asbestos," he says. De Sources ofasbestos fibers in ambient air include natural rock. Rock outcrops near this park north of Coalinga, Calif., have been estimated to contain up to 50% short- spite that limitation, phase-contrast microscopy is not a bad technique for an asbestos mill or plant, where one can reasonably assume that most of the fibers in the air fibered chrysotile asbestos are asbestos. 32 March 4,1985 C&EN HWBUI0002847 However, it was discovered early on that measuring asbestos in ambient air is very difficult. "It's a problem of a needle in a haystack," says Exxon's Lynch. "You find a little bit of asbestos in the presence of an enormous amount of particulate matter." Therefore electron microscopy techniques are used to measure asbestos accurately in ambient air. Samples are collected and treated to remove organic materials. Clumps of fibers are broken up so that the individual submicron-sized fibers can be seen. Transmission elec tron microscopy (TEM) can give the crystallographic structure of a fiber to distinguish asbestos from other fibers. TEM is the definitive technique for measuring as bestos in ambient air but it costs $300 to $500 per sample. In addition, not many labs are set up to do that kind of analysis. "[Fewer] than 20 labs in the country have the combination of equipment and experience to do TEM," says Ian M. Stewart, vice president of McCrone Envi ronmental Services, part of Walter C. McCrone Asso ciates, a microscopy firm based in Chicago. For that reason, scanning electron microscopy (SEM), which is cheaper and more accessible, is often suggested as a substitute for TEM. But Small and Stewart think the ability of SEM to distinguish chrysotile fibers is limited because of poor contrast. In either electron microscopy technique, the* number of fibers seen does not reflect the number in the original sample, because the sample preparation techniques break up the fibers. Therefore, the results are expressed as the mass of asbestos per volume of air. Ambient air levels Out in the country, away from man-made or natural sources of asbestos, there is less than 0.01 ng of asbestos per cubic meter of air, estimates William J. Nicholson, a physicist who is associate director of the environmental sciences laboratory at Mount Sinai School of Medicine. "But in a typical urban environment, there's about 3 ng per cu m over 24 hours," he adds. In the 1970s, concen trations of asbestos in New York City air ranged from 20 to 60 ng per cu m. Asbestos in outdoor air in cities probably stems from construction and remodeling or demolition work on buildings and from car brakes. In 1978, Nicholson measured the levels of asbestos inside 10 schools that contained visibly damaged as bestos building materials. The concentration of chry sotile ranged from 9 to 1950 ng per cu m. Other studies have found asbestos air levels inside buildings with as bestos-containing materials ranging from 1 to more than 500 ng per cum. Judging whether these low concentrations of asbestos are a health risk requires relating them to the higher levels that epidemiologists found were hazardous to workers. Unfortunately, the occupational doses are measured in fibers per volume of air, whereas ambient air levels are^measured in mass per volume of air. Ac curately interconverting the two types of measurements is virtually impossible. 'The fibers suspended in ambient air are different from those in an occupational setting, not only in con centration but in size distribution," Lynch says. "Vir- Asbestos abatement worker on the job last summer in Maplewood, N.J., elementary school tually all of the fibers [in ambient air] are small." That means that a nanogram of asbestos from the workplace might contain 2000 relatively large fibers, but the same mass in ambient air might be made up of 70,000 smaller fibers, to use an example from the NRC report. However, the NRC panel decided to interconvert the exposure measurements from the two environments by assuming that the mass of an asbestos fiber found in the ambient air was equivalent to the mass of a fiber, of a particular dimension, found in the workplace. That as sumption underestimates the number of fibers in am bient air and overestimates their size. And that assumption also introduces a huge uncer tainty in the panel's risk assessment, because fiber size has been hypothesized to be related to asbestos's toxicity. "That's why the lower limit of our risk assessment is zero," says Lynch. "Longer fibers are definitely toxic, but some researchers say that short fibers have no ac tivity." Some animal experiments indicate that shorter-length particles have little carcinogenic effect, perhaps because they are small enough to be cleared by macrophages. "However, the majority of the NRC committee does not agree that small fibers are totally inactive, although they may be less toxic," Lynch says. "It just isn't known." In contrast, the Canadian report concluded that thin as bestos fibers longer than 5 pm are hazardous. Qualitative risk assessment Using all of these assumptions, the NRC committee calculated the risks of developing mesothelioma and lung cancer from breathing asbestos in the ambient air over a lifetime. The panel calculated that at an exposure level of 0.Q004 fiber per cc--about the level of asbestos March 4.1985 C&EN 33 HWBUI0002848 Special Report Underlying cause of asbestos's toxicity still unclear I 1 "Everyone's got an interesting theory and there are data sets to support eafch and every one. But when you come down to tions of asbestos that workers were ex posed to years ago may never have been kept or may have been lost. And inaccu i i the essentials--that is, what is it about asbestos that imparts its activity--your rate use of mineralogical terms in the scientific and medical literature prevents guess is as good as ours," Arthur M. precise characterization of exposure. Langer of Mount Sinai School of Medicine More recent experiments in animals 6 told federal officials last fall. The group and in tissue culture--where conditions & was gathered for a briefing chi the National can be carefully controlled--overcome I Research Council's report on nonoccu- some of these difficulties, interpreting pationat health risks of asbestiform fi such studies and extrapolating the con bers. clusions to humans can be controversial, Although the state of scientific knowl however. edge isn't quite SO bad as Langer's remark The cellular mechanisms underlying implies, there's remarkably little that can asbestos's carcinogenicity are being ex 1 be said with certainty about the root of plored. The multistage theory of cancer asbestos' toxicity. Epidemiological studies holds that two steps are necessary in the indict asbestos as causing pulmonary fi development of cancer. In the initiation brosis (asbestosis), lung cancer, meso step,DNA in a cell is damaged or mutated. CrocldoIHe fibers In hamster thelioma (cancer of the lining of the lung In the promotion step, the altered cell is respiratory trad. Small spherical and abdomen), and perhaps gastrointes encouraged to divide and proliferate. cells are macrophages tinal cancer in workers exposed to large Although the evidence is contradictory, amounts in their jobs. ;most laboratory studies show asbestos icity may be fiber size. The fiber has to But only a few clues have yet been fibers don't damage DNA. Therefore, as reach the lung before it can do damage. uncovered to link the physical and bestos has not been shown experimen "Fibers above a certain diameter are not chemical properties of the various forms tally to be an initiator of cancer. even inhaled," says Brooke T. Mossman, of asbestos to their biological activity. For Both laboratory and epidemiological associate professor of pathology at the example, it's not clear if the same prop studies point to asbestos's role as a pro University of Vermont and a member of erties trigger all the health effects or moter of lung cancer, however. For in the committee that prepared the NRC whether a different characteristic is re stance, asbestos exposure multiplies the report. Three over about 3 /mi in diameter sponsible for asbestosis, say, than for lung risk of lung cancer from cigarette smok probably are screened out by nasal hairs cancer. ing. There also is evidence that asbestos or other protective mechanisms in the Important details that could help tie may help carry certain carcinogenic hy upper respiratory tract. specific characteristics of asbestos fibers drocarbons into cells. In addition, inter Some researchers think that very small to disease are often missing from epide action of asbestos fibers with cell mem asbestos fibers also may not be toxic, miological studies that span several branes favors the release of substances although the NRC panel concluded no decades. Records of the exact types, or important to the carcinogenic process. minimum size of fiber could be declared igins, dimensions, and fiber concentra- A key determinant of asbestos's tox- not to have any effect on health. Short fi- in New York City air, according to the conversion factor the panel chose--the risks of developing mesothelioma range from zero to 350 per million. At any exposure level, the risk of developing lung cancer depends on an individual's sex and on whether he or she smokes. The greatest risk is to male smokers, ranging from zero to 290 per million. Female nonsmokers were calculated to have the lowest risk, ranging from zero to 13 per million. The committee also calculated the risk of a lifetime of exposure at a higher level, equivalent to the level that might be found in buildings with asbestos surfaces. Those risks ranged from zero to 1700 per million. The Canadian report, however, states that "asbestos in building air will almost never pose a health hazard to building occupants," unless elevated exposure is caused by disturbing the asbestos. "There's an enormous amount of uncertainty" in as- sessing the risks of asbestos fibers in ambient air, Nich olson says. 'The fibers are measured in so many different ways. There's the possibility of differential toxicity. The fiber dimensions are different in different environ ments." Nicholson recently prepared assessments of asbestos health risks for EPA and OSHA. His quantita tive risks findings are generally in the same ball park as the NRC panel's. "In all of these decisions we state our assumptions," says panel member John Van Ryzin, professor of bio statistics at Columbia University. "I was very insistent that we report what our uncertainties are." The NRC panel's charge was to assess the risk from nonoccupational exposures to asbestos, not to recom mend what to do about them. Yet the uncertainties in herent in calculating risk mean policy makers have difficult decisions ahead in tackling how to manage as bestos exposure. 34 March 4, 1985 C&EN HWBUI0002849 smaybe breathed in and out without. "Jfomiffin me rats when We fibers fit the kpy ,, sirface chemistry."langer and graduate llJi ________________A _ _a___ ^ (- iLx 1 j,* M.i I^ Whip to any great extent In the lungs. jdlfhensjjMfe. Other researchers JwiSe student Robert P. Nolan have been a',sw'i "howevOr,'^i||at the fourxJihat silicon carbide fibers and ^ studying how minerals communicate with fdefense against foreign 1 naturally Aocdnrl^lMMiil " ^fefl thdmbranes fhrough information on may cope with short libers mesothelioma In similar experiments ^We'ihVieral suriaoe. ^ l- *-'- F< v. '"^^`If slze and shape, rather thanchenfo- r^K^Morphology may be important in get- tirjg the Hber to tpe site where it does ' any .proposed suffl|^||r|fi^pi; damage," Langer says. "But once at the B_ ci|a of tf>e cells prig need tobe Studied ^tgrget sito^ surface characteristics take ^ -T- -- can sweep toe engulfed'ffbeirs example, epidemiological studies1 <1 ' ewer. The nature ot the chemical func-; ^ fo eventua,fy1,0 coughed out, spit out, ...workers exposed to fibrous glass have ' tionallties, their spacing, number, and a^y%D*, swsjfowed. Some may stay in We body, shpwn a 'small Increase In r*spiraifry ^.geometrical configuration on a mineral ' traveling to the lymph nodes, but there is cancer. Until abouH6 years agorhewg _ purface are all going to affect how that L no direct evidence that this causes dis- ever* most glass fibefs ware larj^||pf ' mineral communicates and therefore in \.ea^*?OMman says. ' teracts wtiha cell," he adds f fibers of intermediate size, thin enoucW ISSiibe^Monfe^pjdviE^e^^^ "The question is more than academic. Kfc-w p ^t^Ktterlh^lung but too longto be entirety , .if surface chemistry is the key, then there jf.V`' ^ suotoufideid by Wactophages, may be a lt^|ibeilla:^ik^lslMiS^BiPi . would be a rational basis for the argument V.- Culprit. hi fact, one theory holds that ft is ,Jhat certain forms of asbestos are less tbp long. Win dimensions of asbestos ft- Its critics, however. For one flung, itls . $>xic than others. Some scientists believe, bers, raWer than any specific chemical experimentally difficult to comprohl on the basis of epidemiological studies, .property, that it is the key to Weir tox- separate fibers by size. A batch olilll8 Wat chrysolite fibers produce ter less : `T . ^??s^t^`;4i8tSinafly-Of'She lengW can contain fibers , mesothelioma Wan crocldolite or amosite, different sizes And milling min Although the Issue is hotly debated grew out of experiments per erals to reduce their lengW also can pro If certain chemical functionalities could formed toy We late Mearl F, Stanton and foundly change their crystallinity and be pinpointed as the bad actors in as National Cancer Mp surface characteristics, says Langer bestos toxicity in theory modifications to ^ ^tute. Thev inserted fibers of different sizes Other workers have statistically re ' toe surface ppudd result in less hazardous and types-^-We major forms of asbestos examined Stanton's work with different forms of asbestos. For instance, a Cana ft " ''raf wSH asother, nonasbestosfibers--into results FreocW researchers conclude that dian government-industry organization the fining of We lungs of rats They con- We ratio of lengW to width (known as the called Socfete Nationals de I'Amiante Is /oluded that the factor most tied to meso- aspect ratio) k, most important and that It supporting research in Langer's lab and Welioma In their experiments was a par- is not possible to separate We effects of elsewhere on a modified phosphorylated tiCutarstae of fiber (specifically, fibers length and width. Langer recalculated the Chrysolite. "So far. We phosphorylated cfeaiihfe^85!^m`lft diameter ant^pp^ date for crockfelite and judged fibers 4 to fiber appears to have for less membrane Wan *pra), -rather Wan ^particular 8 pm long were most toxic, rather than Activity as compared to untreated fibers," dhernkfellkimposttlon Besides the vaft- those longer than 8 pm Langer says "The implications of pro ous types of asbestos, fibers of borosili- "Fiber dimension may be yefy impor- ducing a safe fiberare of vast pragmatic pateplaas, potassium titanate, and some 1801," Langer says, "but,other factorsare importance. The concept and work are aluminum compounds caused m||i||| at least as important. You cannot dismiss exciting." , A 4,5 "o*` -* - " <Ti < i-f 1Mkw.ivpi;t 1 >**, AJS 1 A*- ** For the government to regulate a substance, it must first determine that the material poses a hazard. Then federal agencies must decide if they can take steps to reduce or eliminate the risks. In the case of asbestos, there is clearly an occupational hazard to workers. OSHA currently is trying to lower the permissible exposture level in the workplace to either 0.5 or 0.2 fiber per cc. The Consumer Product Safety Commission banned the use of asbestos in spackling compounds and artificial embers for fireplaces in the mid-1970s. A few years later, manufacturers voluntarily removed asbestos insulation from hair dryers after CPSC began an investigation. EPA has the authority to ban hazardous chemicals and mixtures under the Toxic Substances Control Act. In the 1970s, it forbade further use of sprayed-on asbestos materials as a hazard both to the workers applying the material and to people near the construction site. That use of asbestos had become a popular method of fire proofing and insulating steel girders. In 1983, EPA began drafting regulations to ban im mediately some other uses of asbestos--including ce ment pipe and flooring and roofing products--and to phase out the rest over a 10-year period. But in early 1985, the agency said that, under TSCA, it must give other federal agencies a chance to regulate hazardous substances before it acts. So EPA has turned over its proposed ban on asbestos to OSHA and CPSC. That move has angered critics in the environmental movement and trade unions and even within EPA itself, who suggest the action is'simply an attempt by the Reagan Administration to stall further regulation of asbestos. However, if OSHA and CPSC don't move on the issue, the problem will end up back at EPA. Yet some who are concerned about exposure to as bestos aren't sure that a ban on the material addresses the March 4, 1985 C&EN 35 HWBUI0002850 Special Report r Asbestosabatement requires multidisciplinary teams The costs of 'removing asbestos from governments are required by law to award usually with plastic sheeting, to make a ^buildirtgS Ore enormous. Estimates'for, 'contracts to the lowest bidder; "it's closed environment. ^ay, taking ceiling insulation out of an sometimes difficult to eliminate guys who Decontamination facilities are built, average-sized elementary school can run don't know what they're doing," says including a shower and change room 'from $100,000 to more than $1 million. Morse. "All it takes for a contractor to set isolated by airlocks so employees don't The expense stems from the time and .up ts $20,000 to buy equipment." carry fibers outside and home on their Expertise needed from profession's in "It's a new industry evolving more bodies or clothes. Another airlock is used many different areas if the Job is to be quickly than government can regulate it," to load the asbestos waste onto a truck for done property. says Brent W. Schopfel of Archway disposal. When a bullding owner decides to have Contracting Co., Pennsauken, N.J. Then, negative air pressure is estab -asbestos removed from a property, there Schopfel is a charter member of the Na- lished in the work area. That way, any air often is only a potential hazard from as - tional Association of Asbestos Abatement leaks will be from the outside into the bestos that might be disturbed at a later Contractors, a nonprofit trade association contaminated area, rather than the other date. But once the abatement project formed in January 1984 to try to set way around. Air is drawn in from the out begins, there is an immediate hazard to standards for the industry. side and exhausted through high-effi the workers involved. And if the cleanup In addition to the contractor whose ciency particulate air filters (HEPA) to is not done with great care, there may be workers actually will take out the asbes ^remove asbestos fibers. real danger to the occupants who return tos, a removal project requires, at a min Workers dressed in hooded cover -to a supposedly safe building. imum, an architect or engineer to draw tp alls--called moon suits--and wearing . "An asbestos removal project is realty specifications and coordinate the work as respirators then remove the material. A a demolition project that leaves the well as an analyst and air-sampling labo number of techniques, such as scraping, 'building standing," says Roger G. Morse, ratory to monitor fiber levels. Every em are used and the material must always be a Troy, N.Y., architect whose firm spe ployee must be trained in safe work kept wet to keep down dust levels. The cializes iri asbestos work. "At the same practices, and the Occupational Safety & waste, still wet, is double bagged and time, there's potential for contaminating Health Administration requires they be placed in containers to be taken to a the whole building. You need people who given physicals at regular intervals. landfill each day. No material is allowed know what they are doing watching over Before the work can start, the con to accumulate. Both the transporter that the whole thing." tractor must notify local and state agen carries the sealed waste and the landfill The asbestos abatement industry is cies and the Environmental Protection that receives the asbestos must be cer mowing by leaps and bounds and the po Agency, Schopfel says, and then wait the tified. EPA requires that the asbestos be tential for problems from shoddy work is required period to give them time to re buried under at least 6 inches of dirt within growing with it. For example, many local spond. Next, the work site is sealed, the day. Finally, the area is carefully real risks. Substitutes must be adequately tested, for ex ample. "I'm concerned that if some material is not called asbestos, it is automatically exonerated from biological wrongdoing," says Langer. Nicholson points out that asbestos in most products being manufactured today--cement pipe, for exam ple--is tightly bound and not likely to become airborne easily. "The current hazard is from asbestos already in place--about a million tons of friable asbestos in insu lation and pipe lagging that's going to have to be re moved someday. That's a much greater problem than continued use of asbestos." Asbestos abatement A recent EPA report estimates that 15 million children attend schools where friable asbestos is present. An EPA survey of buildings other than schools estimates that 700,000 commercial, residential apartment, and federal buildings contain friable asbestos. The only current federal regulation that requires asbestos be removed from buildings is an EPA rule saying asbestos materials must be taken out of a building before it is demol ished. Two factors, however, are encouraging a growing trend to rip asbestos materials out of buildings wherever these materials are found. One is EPA's asbestos-inschools program, which requires school districts to in spect their buildings for crumbling asbestos. The second is building owners' fears that occupants may sue over future asbestos-related disease. Asbestos abatement-- which includes both removal and sealing off asbestos in various ways--has become big business. The asbestos-in-schools program has been lambasted from all sides for publicizing the presence of asbestos in schools but not giving school authorities enough help--either technical or financial--to deal with the problem rationally. EPA publishes a booklet called "Guidance for Con trolling Friable Asbestos-Containing Materials in Buildings" to help school authorities decide what to do when they find asbestos. It does not specify, however, that asbestos must be removed. Local officials must judge if that is necessary. Other options are to leave the as bestos-containing material alone, enclose it, or encap sulate it with a sealant that binds the fibers tightly. Many authorities in asbestos control agree that the problem is too complex to formulate general regulations that would fit every building situation. 36 March 4, 1985 C&EN HWBUI0002851 n o te byw rnm H . Spain, (MorsfeImfflun otTt termined by phase-contrast optical mi croscopy. However, that technique can pick up only large fibers and can't distin guish asbestos from other fibers. EPA has been trying to draw up rec ommendations for final fiber levels and the best way to determine them, says Michael E. Beard, a chemist with the agency's ft&D lab in Research Triangle Park, N.C. The agency is evaluating the three techniques--phase-contrast mi croscopy, sdanping electron microscopy, and Jtansmisglbff electron microscopy (TENfp-toat Currently are used in deter Abatement worker scrapes asbestos-containing Insulation from celling cleaned by wet wiping and vacuuming with a HEPA-equipped vacuum. "The moon suits are uncomfortable. They are hot and sweaty and it can be tough to work in a respirator," says Schopfel. "But in our company, produc tivity is pretty high. There's nothing else to do but work. It's hard to talk when you're wearing a respirator and you can't eat or drink. Any employee who takes off his respirator during work is fired." Air samples are taken regularly throughout the entire operation to monitor fiber levels ami check for leaks outside the work area. Also, contractors usually are required to get the fiber levels--which are raised unavoidably during the removal work--down to a specified level before they can be released from the job, a pro cedure known as clearance monitoring. "Clearance monitoring is a release mechanism saying toe contractor has achieved certain levels under the best available technology," says tan M. Stewart, vice president of McCrone En vironmental Services, "tt can't say you have a safe building. No one has told us what a safe level is." Many contracts specify a final fiber level of 0.01 fiber per cc or less, as de mining postabatement asbestos air levels. The goal is to find an effective technique that's practical to use. For instance, some researchers think that toe ihdoor asbestos air levels after abatement work ogggftt to be as tow as those outdoors. However, to measure such very low levels yvould require elec tron microscop^-^and pntoably the very expensive hd nd?Widely available 1EM technique. "If ail jobs are required to use TEM," says Stewart, "toe turn-around time for samples will go to months rather than days. What do you do, leave toe plastic tents up and buildings empty while you waft?" .. , , , So, as seems the case with everything efeetxlmtorntng asbestos control, EPA is ^facb&lftitlt1some difficult judgment calls on asbestos air monitoring. "You have to decide on a case-by-case basis whether to remove asbestos," Selikoff says. "Asbestos does not constitute a hazard unless it is inhaled. Unless it can become airborne, there's no urgency in removing it. If it can be sealed off or is inaccessible and in good condi tion, it doesn't need to come out unless it will be dis turbed by repairs or renovation. This can be planned for." However, local school boards often lack the expertise and are too short of funds to hire experts to help them make the right decisions. "EPA is going in the right di rection, but [it doesn't] have enough qualified people to supply guidance," Nicholson says. "Right now, some school administrators are so frightened that they panic when they see a crack in the ceiling. Others have the stuff falling all over and are not doing anything." Says Susan Mazzochi, cofounder of Parents Against Asbestos Hazards in Schools, based in Maplewood, N.J.: "We discovered asbestos in our children's school and were shocked that the school board wasn't acting. The school board didn't want to do anything because it would cost money. In absence of any law that states how the problem should be addressed, it becomes a power struggle between the parents and the school board." Another group that thinks EPA should take a more active role in asbestos abatement policy is the Service Employees International Union (SEIU), which repre sents about 100,000 school workers. Maintenance workers such as SEIU members are often the individuals expected to remove or clean up damaged asbestos ma terials in school buildings, sometimes with inadequate training and protective gear. SEIU petitioned EPA in late 1983 to require corrective action when hazardous asbestos is found in schools and to issue regulations to protect school workers, who are not covered under OSHA. When EPA refused to act on all of the union's requests, SEIU filed a lawsuit against the agency in September 1984. EPA is in an awkward position because no one can say exactly what levels of asbestos are hazardous. In certain situations where damaged asbestos is flaking into work areas and circulating through air-conditioning systems, the decision to remove it is straightforward. But most cases are not that simple. "The appropriate action should be determined by a complete building survey by a qualified individual," says William H. Spain of the environmental health and safety division of Georgia Institute of Technology. Spain March 4, 1985 C&EN 37 HWBUI0002852 Special Report NRC's estimated dancer risk has wide margin of uncertainty Exposure group LUNG CANCER-- Male smoker Female smoker Male nonsmoker Female n'onsmoker Individual lifetime risk of developing cancer, per million* Exposure at 0.0004 fiber/ccb Exposure at 0.002 flber/ccc 64 (0 to 290f 23(0 to 110) 6 (0 to 22) 3 (0 to 13) 320 (0 to 1500) 120 (0 to 530) 29 (0 to 130) 15 (0 to 66) MESOTHELIOMA__ All 9(0 to 350) 46(0 to 1700) Note: For example, the risk of developing lung cancer for a male smoker who is exposed throughout his lifetime to an asbestos concentration of 0.0004 fiber per cc probably is about 64 in 1 million, but may range from 0 to 290 in 1 million, a Lifetime assumed to be 73 years. Exposure occirs continually from birth, b Approximately equivalent to asbestos concentration in urban outside air. c Approximately equivalent to asbestos concentration in U.S. schoolrooms with asbestos surfaces, d Range of estimates. Source: "Asbestiform Fibers: Nonoccupational Health Risks," National Academy Press, 1984 and his colleagues in Georgia Tech's asbestos programs group offer courses for building owners, architects, contractors, and others on managing asbestos. Their course on supervising asbestos abatement contracts is so popular that they have offered it 15 times since its in ception in May 1982. Georgia Tech is the site of one of three new asbestos information centers, funded by EPA and opening this year to answer questions about controlling asbestos. "Bill Ewing [William M. Ewing, also at Georgia Tech] and I could spend 10 hours a day on the phone talking about asbestos," Spain says. Spain does not think air levels of asbestos should be the criteria for determining the need for abatement. "Air samples are like a photograph, they reflect only the circumstances at that particular time. Air levels that are low during normal activities might be higher during certain maintenance procedures that might disturb the asbestos, like changing light fixtures or running tele phone lines," he. says. Given the popular notion that even the smallest bit of asbestos is deadly, many school systems and building owners are rushing to take it out. Unfortunately, this can sometimes turn a potential risk into an actual one. "If building surveys and abatement work are not done correctly, the hazard could be made many, many times worse than it was initially," Spain says. "A substantial, or at least a noticeable, portion of abatement projects are being done in such a way as to put people at risk." The Canadian report also points out that removal projects can increase the risks of asbestos-related disease. The danger lies in not containing the asbestos as it is removed. Both abatement workers and bystanders then are exposed to loose fibers as the removal work is going on. In addition, asbestos fibers, which take a long time to settle out of the air, can become caught up in the aircirculation system of the building and subject the occu pants to sizable doses once they return to a supposedly clean building. Indeed, tenants of the 17th floor of the Medical Towers building in Houston have filed a $110 million suit against the building manager and a contractor who remodeled the 18th floor last summer. The plaintiffs charge they were exposed to asbestos dust and now have increased risk of getting cancer. The consequences of acting too hastily to remove as bestos are also apparent in New Jersey, where about 300 schools were scheduled to have asbestos taken out last summer. As the opening of the fall school term ap proached, it became clear that many of the jobs had been done sloppily and with inadequate monitoring. Most of the schools opened on time anyway. O WT- W; W -Jf'' Bureau o f Mines photo Magnified 148X underpolarized light, chrysotile fiber bundles appear blue and purple. The characteristic hollow-tube structure of individual chrysotile fibrils is visible in the transmission electron microphotograph (35,000X) 40 March 4. 1985 C&EN HWBUI0002853 I (Property liability lawsuits multiplying rapidly * ' PLj When Manville Corp. (formerly Johnsr ' into the buildings, Identify the asbestos, Ifh-Manville) filed a bankruptcy petition In remove it, and replace it with substi ||^ August 1982, It was seeking protection, tutes," she adds. The first hearing in the from millions of dollars In claimsJty' 1 State's suit is scheduled for later this f%" - more than 16,000 people suffering from month. ,*>' If ` Vr asbestos-related diseases. Now, how- If theslze of Mtevylahd's suit turns out | ever, other asbestos manufacturers are to be .typical, 'a crude extrapolation - bding deluged with lawsuits from build- yields nteny billions ofdbllare at stake In, ing owners. These fast-multiplying suns from stato governments alone. {: ? property damage suits may turn out lo beBusinesses, local governments, ind g even more expensive than the healthp--rivate homeowners also are potential l ' related ones. plaintiffs in such suits. So Is the federal | For example, last September the government, but the Department "of ffc state of Maryland filed suit against 47 -Justice indicates tt probably won't sue. p- asbestos producers for the cost of However, aJustice'Department report | cleaning asbestos out of 3000 buildings encourages school systems to by to l^jftmedlty'lhe state. "The suit asks for recover the costs df their abatement t $500 million in compensatory dam- projects from asbestos manufac [ ages," says Evelyn O. Cannon, assistant turers. I attorney general. "We also asked the : A decision last foil tty a federal Judge P court to require the defendants to come in Philadelphia cleared the way for a f- class action suit by schools against as bestos producers. Judge James M. Kelly ruled that a combined suit would let thousands of small school districts sue to recover toe money they've spent to remove asbestos without being bur dened by prohibitively high legal costs. Districts may sue on their own for compensation, his ruling said, but all punitive damages will have to be part of toe class action. Because Manville is in bankruptcy, it Can't be sued directly as the other as bestos producers can. Claimants against Manville instead must petition the bankruptcy court. When a deadline ex pired la^t Jan. 31, more than 3500 property damage claims had been filed. For other companies not under the protection of Chapter 11, toe suits will continue to snowball. "Most of the contractors who have been hired by the school boards to perform asbestos removal work have little experience in this specialized and sensitive field," states a report issued last August by New Jersey's De partment of the Public Advocate. "Because many good contractors are overextended, there is a lack of qualified asbestos removal workers." As a result, inspectors found workers tracking asbestos out of sealed areas, flushing asbestos down toilets, not wearing protective respirators or clothing, and hauling asbestos away in private cars, as well as numerous other abuses of good work practices. To counter such abuses, there should be some way to demonstrate who's qualified to do asbestos abatement work. Some states already have contractor certification requirements. An incentive for the rest of the states to introduce certification procedures is built into the As bestos School Hazard Abatement Act of 1984. That law, which gave EPA $50 million in fiscal 1985 to assist states and local school districts with asbestos control, requires states to certify contractors. The asbestos programs group at Georgia Tech is de veloping a model one-week training program for as bestos abatement supervision under an EPA contract. Another organization, the National Asbestos Council (NAC)--composed of contractors, building owners, ar chitects, analysts, and other professionals concerned about proper asbestos abatement--is developing training materials for.small contractors and maintenance personnel who have to deal with asbestos. A different problem is starting to put even wellqualified contractors out of work, however. "We're starting to hear of contractors that can no longer get li ability insurance," says McCrone Environmental Ser vices' Stewart, who is past president of NAC. "In the past two weeks I've heard from at least 15 contractors who are losing their insurance," echoes Brent W. Schopfel, a contractor who is a charter member of the National Association of Asbestos Abatement Contrac tors. Insurance companies, burned by massive personal injury and property damage claims against asbestos manufacturers, are specifically excluding asbestos abatement work as contractors' general liability policies come up for renewal. "If something isn't done, all of the abatement work is going to grind to a halt," says Stewart M. Huey, execu tive director of NAC. He suggests that state insurance commissioners may have to create an assigned risk pool, as is done for workmen's compensation. Or the federal government could start a reinsurance program, as is the case with flood and nuclear power plant insurance. "It's a nasty problem and a lot of people are working on it," says Schopfel. "It's going to be an interesting summer." All of the problems with asbestos abatement are ex acerbated by panicky, oversimplified responses to a complex issue. "I think we ought to control asbestos," says Langer. "We should not tear it out indiscriminately and then tax society $20 billion. In some cases it may not have to be removed. Where it does, we don't have the trained people to remove it properly and we may in crease risks by taking it out. We live in a chemical society. Let's learn to control and live with these materials." Reprints-of this C&EN special report will be available at $3.00 per copy. For 10 or more copies, $1.75 per copy. Send requests to: Distribution, Room 210, American Chemical Society, 1155--16th St., N.W., Washington, D.C. 20036. On orders of $20 or less, please send check or money order with request. March 4, 1985 C&EN 41 HWBUI0002854