The first three papers in this issue, "Guidelines to Chemical Hazard Evaluation," "Highlighting Safety Practices to Students,"and "Lab Safety Questionnaire" and the accompanyingmaterial on OSHA constitute a seminar on laboratory health andsafety. Stimulated by the A,CS Tenth Biennial Education Conference, the seminar provides information on regulatory, toxicological and instructional matters o f importance to those responsible for the operation of academic chemical laboratories.
Stephen Altman Washmgton, D C
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Guidelines to Chemical Hazard Evaluation
Anyone who uses chemicals in a workplace ought to know in what circumstances the substances are potentially harmful and how to deal safely with them.
If vou've been hearine a lot about the thousands of harmful substanres 10 which workers are exposed. In11 don't know a thine al~outhow rhsr harmfulness is determined, you're not alone. The field of industrial toxicology is not the meat of everyday conversation among people uninvolved as professionals in promoting occupational health. But if you are an employer-either a t an educational institution or in the private sedor-the health of the people who work for you is your business: you are involved. Here, then, is your introduction to the evaluation of chemical hazards. Toxicology is a hybrid science which draws upon the accumulated knowledge of several other fields, including biology, chemistry, biochemistry, pathology, and pharmacology. It is a comdex studv. involved not onlv with chemicals and biologic mechanisms b i t with the cruciaiinteractions that take when they come together. The toxicologist investigates the harmful actions of chemicals on biologic tissue, but usually has a specificand practicalgoal. In the course of exploring the potential of chemicals to do harm, often testing is performed chieflv to determine the conditions under which the chemicals may be used safely. The science has developed three main branches: forensic toxicology (dealing with the medical and legal aspects of human poisonings); economic toxicology (dealing with the harmful effects of substances which are deliberatelv admin----istered to biologic organisms to achieve some specific purpose, i.e.. drugs. food additives. and ~esticides):and environmental tO6co1oYp; (dealing with the harmful effects of substances to which neonle are unintentionallv exposed, as in the environment, in fhod, and in the work~iacej.Industrial toxicology is nart of this last division, and is concerned with the harmful potentials of the raw materials, intermediates, and finished products encountered by workers ~~~
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A toxicsubstonce is one that demonstrates the potential to induce cancer, tumors, or neoplastic effects in man or experimental animals; to induce a permanent transmissible change in the characteristics of on offspring from those of its humon or experimental animal parents: to cause the production of physical defects in the developing human or ezperimentol animal embryo; to produce death in animals exposed uia the respiratory tract, skin, eye. mouth, or other routes in experimental or domestic animals; to produce irritation o r sensitization of the skin, eyes, or respiratory passages; to diminish mental alertness, reduce motiuation, or alter behauior in humam; to adversely affect the health of o normal or disabledperson of any age or of either sex by producing reuersible or irreuersible bodily injury or by endangering life or causing death from exposure uia the respiratory tract, skin, eye, mouth, or any other route in any quantity, concentration, or dose reported for any length of time."
It's a long and encompassing definition, reflecting the fact that toxic substances vary in several ways: the forms of life they will affect; the mechanisms by which they do their damage; the conditions under which they are harmful; and the relationship between given dosage or concentration levels and the effects they will produce. "Toxicity" is a relative term that refers onlv to a chemical's ~ o t e n t i ato l do harm to biologic tissue. w h e n dealing with any particular substance, the &dustrial toxicoloeist - has to take into account its specific toxic properties as they reveal themselves in experimental animals
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Toxlcitv and Hazard Defined Each year the National Institute for occupational Safety and Health (NIOSH) ~ u b l i s h e its s "Registry of Toxic E f f e c t s of ~ h e m i c a l ' ~ u b s t & c e s . "The 1976 edition lists 21,729 different substances which meet this definition 140 1 Journal of Chemical Education
Anyone who uses chemicals in a workplace ought t o know in what circumstances the substances are potentially harmful, and how to deal safely with them. This introduction to the evaluation of chemical hazards published first in the September, 1976 issue of Job Safety and Health, provides a briefing in industrial toxicology, a basic understandingof legal requirements, and guidelines to help keep health hazards in the workplace to a minimum. Although aimed at the industrial employer, the information and advice is also applicable to the University community in its role of providing work space for and as employer and mentor of both professionaland student chemists. THE COVER: Cover photo by George Kew, University of Arizo-
na.
As an employer [or teacher], i t is your legal responsibility to know your own workplace, to find out which substances and procedures may be unsafe, to inform your workers of any potential chemical hazards, and to take steps to alleviate them.
durine laboratorv tests. Only then can he or she begin to calculatPthe likelil;ood of harm to human heings who will encounter the substance in a particular quantity or manner. The of is called hazard. Here the data ob.~-likelihood --. .--~ ~~- harm tained from exposures of experimental animals under lahoratory conditions must he considered in conjunction with the actual exposure conditions human beings will face. So in order adequately to evaluate the hazard of a toxic suhstance to he used in the workplace, the industrial toxicologist must have not just experimental data hut the following information as well. ~
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Stlsceptibility of workers who face potential exposure to the substance. Different groups are particularly susceptible to certain
toxic actions. It may not be wise, for example, to expose female workers of child-bearingage to a potential cause of birth defects. The expected frequency and duration of worker ezposures. The toxic effects of some substances may appear upon acute exposures, defined as those which are relatively brief, often involve large doses or concentrations, and are often accidental and unpredicted. Other substances may cause harm when workers are involved in chronic, or extended, exposures to relatively low doses or concentrations. The physical choroeteristies of the substance as it is encountered on the job. Solids, liquids, and gases all pose specificproblems. Some liquids, for example, have a high vapor pressure; that is, they vaporize readily. If the vapors of such a chemical are toxic, then its high vapor
pressure may increase its atmospheric concentration and therefore its hazard. ~~-~~~ On the other hand. while the vanors of another chemical mny Ire equally IIIXIC, its wpnr prr-wre may Ire so low that under rylllcal wurkplnrp rtmprratures only small amounrs d r h e chcm:ral w i l l enter the ormosphere-and so the airborne harard will he n m . paratively small. The warning properties of the substance. Some substances issue their own alarm when workers are ex~osed.The vapors of chlorapicrin, far example, are highly toxic, butchloropicrin is also a potent lachrymator. It is popularly known as tear gas. Anyone exposed to the vapors of chloropicrin simply must get away, and fast; so no one is likely to be exposed to large concentrations of the chemical long enough to he injured systemically. By contrast, consider methyl bromide, a widely used, highly toxic fumigant. It has a high vapor pressure but, unlike chloropicrin, it has no warning properties. Human beings cannot sense its fumes in the air, fumes which are anaesthetic and narcotic and which can cause irreversible damage and even death. The hazard here, of course, is very high. The specific conditions under which worker exposures may take place. These conditions are often complicated by a variety of factors: heat, humidity, vibration, noise, and extreme exertion, all of which may affect the responses of workers to the toxic properties of a chemical. One other element intrudes: the fact that workers are usually exposed not to a single chemical substance, hut to several at once. Toxicologistslack a broad understanding of the way in which two or more chemicals act jointly on the body. Who Does the Testing?
Many companies that produce or handle large quantities of chemicals employ full-time toxicologists to screen new suhstances. Others engage the services of private toxicology consultants. Only the larger chemical producers have in-house toxicology laboratories; others contract for laboratory work hut often have their own toxicologists plan and monitor the proerams. Among the advantages of an in-house research . toxicology lahoratory, according to toxicologist Henry F. Smvth, Jr., is "the possibly greater secrecy concerning product; about to he introduced when all studies are conducted within the corporation." (Smyth is adjunct professor of industrial toxicology a t the University of Pittsburgh Graduate School of Public Health.) Another definite advantage, Smyth
states, "is that the corporation has full control of scheduling of studies and can accelerate work on a single project when marketing plans require it. This is much less possible when contracts with an outside lahoratory are involved." Also, an in-house facility makes for closer contact and easier consultation between toxicology researchers and other company departments. Since the researchers are part of the firm, says Smyth, "Their familiarity with all of the corporation's products makes them more useful as consultants than would be specialists from outside the corporation." But, as Smyth points out, the major drawback is cost. To support its own toxicology testing facility, a firm must have a sufficient scale. which means not only financial resources but a continuing stream of chemicals and processes which need investigation. There are not many such firms. The issue of cost is the main reason why advance testing of specific toxic substances by industry has rarely been exhaustive, and has often been inadequate. Extensive testing of a new substance is time-consuming, and the delay in putting a new product into use can cost a company money. The tests are expensive and, as Smyth states, "Unfortunately, there is no obvious financial value to harm that has been nrevented." The result has been that most chemical companiks routinely carrv out onlv that testine" reauired . hv law. Food additives, drugs, cosmetics, and pesticides are heavily regulated by federal agencies which, in the case of drugs and pesticides, require and monitor extensive premarket testing programs. The great hulk of industrial chemicals is not so tightly regulated. In NIOSH's "Registry of Toxic Effects of Chemical Substances," for instance, the names of most chemicals listed are accompanied only by their known acute toxic effects. But as the introduction to the "Re~istry"states, "The acute or imrnedistr toxic r f f w doe3 no1 necesssrily chantctcrize the toxicity of those suhstances for which othrrs may predominate, s"ch as cumulative effects from longer term exposure." One reason why chronic exposure data are lacking is industry's common claim that long-termed testing is too expensive. It follows that a lot of surprises have surfaced in recent years. The effects of vinyl chloride, for example, the cancercausing properties of which became evident only after years of human exoosure, could have been foreseen had adequate long-term c&cinogeuic testing been conducted hefore the suhstance was produced commerciallv. Toxicologists often find thernselres pt.rforrning animal tests that simply confirm a toxic rffcct alread!. osinfullv \,isil~lein the human population. Epidemiologic~
