ENCYCLOPEDIA OF ENVIRONMENTAL SCIENCE AND ENGINEERING - EFFECTS OF CHEMICALS docx

271 EFFECTS OF CHEMICALS Almost daily one reads reports in the press about new dangers found or suspected in foods, medicines and other products. Public awareness of possible perils in everyday products has increased greatly. Smoking, asbestos, toxic and hazardous wastes (once called industrial wastes) are widely discussed. Problems resulting from technological advances are being uncovered at an alarming rate. While it is possible to predict, with some accuracy, benefits to be expected from improvements and new approaches in applied science, seldom have serious efforts been made to determine adverse effects resulting from these. The general public is increas- ingly aware of potential hazards from new products and processes and the trend in industrialized countries is toward greater control and regulation of hazardous undertakings. The question as to the more effective approach, gentle per- suasion to gain voluntary compliance or strong legislation for strict regulation, has not been satisfactorily answered. Probably there never will be agreement. In the United States, the Office of Technology Assessment was dissolved. The stated reason was that this Office did long- term studies which were not immediately useful to a legisla- tor. In remarks at the Conference on Technical Expertise and Public Decisions at Princeton University, the then Chairman of the House Science Committee said that it was more desir- able to depend on the views of those most interested in the topic—the lobbyists. The relationship among the air, water, and soil is not a static one. Effects of a pollutant may be demonstrated progressively in the various compartments into which the environment is divided. A substance may be initially present, without apparent ill effects, in one compartment. Later, the same substance, or a demonstrable derivative, may appear in a different part of the environment in a most undesirable way. An excellent example is the high mercury level found in fish. Initially, it was felt that disposal into the marine environment would conveniently remove a bother- some waste. However, by previously unsuspected paths the metal found its way into the systems of game and food fish. Food, thus, has become a secondary distributor of pollutant material. Chemical pollutants may be divided into four categories: 1) Natural chemicals in excess. 2) Naturally occurring toxins. 3) Mixtures of air and water pollutants which produce adverse effects but with only partially defined or undefined components. 4) Synthetic chemicals. The first group includes chemicals such as nitrates and nitrites. Nitrates, for example, can cause methemoglobinemia in infants by reduction of the capacity of the blood to carry oxygen. An intermediate reduction is involved. A famous case in New York involved accidental introduction of sodium nitrite into oatmeal and the resulting problems of “Eleven Blue Men.” The victims, all heavy users of alcohol, apparently tried instinctively to compensate for low salt in the body. Through an accident, sodium nitrite instead of sodium chloride, was placed in salt shakers in a public eating place. The eleven victims all became cyanotic, with the characteristic blue color giving the name to the episode. Nitrites may also react with secondary amines to form nitrosamines, some of the which have been shown to be carcinogenic, teratogenic, and mutagenic, all in microgram doses. Oxides of nitrogen, thought to be significant in smog production, can also form nitrosamines. The second group, natural fungal and plant toxins, usu- ally are introduced into the human ecosystem through acci- dent or carelessness. Conditions of harvesting, storage, and processing have been shown to be of possible importance. An excellent example of the third group has already been mentioned. Mercury was discharged to the receiving water as an apparent ultimate solution to a waste disposal problem. The two components of the system, mercury and water, were assumed to be non-reactive. Unfortunately, the two-component system was, in fact, a multicomponent system and no endeavor was made to determine the complete mechanism. The prob- lem was further complicated by the introduction of edible fish into the chain. Minimata Disease is named for the city in which it occurred. Inorganic mercury was discharged in the effluent of a local industrial plant. Through action of marine organ- isms, the mercury was converted to lipid-soluble methyl mercury, which was taken up in the food chain to fish, the staple of the local diet. 43 deaths and about 700 serious ill- nesses were acknowledged by local authorities in the 1950s. Some unofficial estimates have put the death toll as high as 800. In 1989 two former company officials were given prison sentences for the 1950s pollution. Lawsuits resulting from the pollution were finally settled in 1996. © 2006 by Taylor & Francis Group, LLC 272 EFFECTS OF CHEMICALS In Japan in 1968 about 1800 people developed a malady similar to chloracne after ingesting rice oil contaminated with a chlorinated biphenyl. Known as Yusho or Rice Oil Disease, the rice oil used in cooking had been contaminated by a PCB which had leaked from a faulty heat exchanger. In 1978 an outbreak similar to Yusho Disease occurred in Taiwan and is known as the Yu-Cheng Incident. The cause was the same, a faulty heat exchanger. The last group, synthetic chemicals, includes pesticides and fertilizers used in agriculture, food additives, compounds containing heavy metals, plasticizers, fuel additives, house- hold chemicals, industrial chemicals, therapeutic and pro- phylactic drugs, and drugs of abuse. Food additives may be intentional or accidental. Anti-oxidants and dyes are added routinely to many foods. However, almost any of the afore- mentioned may be accidentally introduced into food, often with most unpleasant results. There is much controversy concerning synthetic agriculture chemicals. Advantages and disadvantages are numerous and no definite decision has been reached concerning continued use of many substances. NTA (Nitrilotriacetic Acid) as a substitute for phosphates in detergents, is another excellent example of conflicting use. The problem is far from restricted to simple direct physi- ological effects. Food additives may be classified as to function. They find use as coloring material, flavor enhancers, shelf life extenders, and in protection of food nutritional value. While valuable, color additives are not always essential. However, many of the foods now enjoyed by modern western society would not be possible, in their present form, without food additives. It is estimated by the World Health Organization that about one fifth of the food produced in the world is lost by spoilage. Preservation, or retardation of spoilage, can be accomplished by addition of chemical preservatives, or by physical means such as freezing, drying, souring, ferment- ing, curing or ionizing radiation. There is some concern that irradiation of food may have adverse effects and leave unwanted residues. Little is known about possible chemical chain reactions. Food additives have been classified by Kermode into five broad groups: 1) Flavors 2) Colors 3) Preservatives 4) Texture agents 5) Miscellaneous In Table 1 are displayed food additives declared by the United States Food and Drug Administration to be “gener- ally recognized as safe.” Not included in Table 1 is a large group of natural flavors and oils. To be on the list an additive must have been in use before 1958 and meet specifications for safety. Materials introduced after 1958 must be tested individually in order to quality for inclusion of the FDA list. Examples of materials formerly listed but now removed are cyclamate sweetners and saccharin. A ban on cyclamates ordered by the US government after tests revealed devel- opment of bladder cancer in laboratory rats fed on a diet containing cyclamates. Further testing, after the ban, found cancer development in the same test species at dosage rates one sixth as large as those which brought about the ban. TABLE 1 Additives listed by the U.S. Food and Drug Administration as “generally recognized as safe.” (Courtesy, Scientif ic American ) ANTICAKING AGENTS Aluminum calcium silicate Calcium silicate Magnesium silicate Sodium aluminosilicate Sodium calcium aluminosilicate Tricalcium silicate CHEMICAL PRESERVATIVES Ascorbic acid Ascorbyl palmitate Benzoic acid Butylated hydroxyanisole Butylated hydroxytoluene Calcium ascorbate Calcium propionate Calcium sorbate Caprylic acid Dilauryl thiodipropionate Erythorbic acid Gum guaiac Methylparaben Potassium bisulfite Potassium metabisulfite Potassium sorbate Propionic acid Propyl gallate Propylparaben Sodium ascorbate Sodium benzoate Sodium bisulfite Sodium metabisulfite Sodium proponate Sodium sorbate Sodium sulfite Sorbic acid Stannous chloride Sulfur dioxide © 2006 by Taylor & Francis Group, LLC EFFECTS OF CHEMICALS 273 Thiodipropionic acid Tocopherols EMULSIFYING AGENTS Cholic acid Desoxycholic acid Diacetyl tartaric acid esters of mono- and diglycerides Glycocholic acid Mono- and diglycerides Monosodium phosphate derivatives of above Propylene glycol Ox bile extract Taurocholic acid NUTRIENTS AND DIETARY SUPPLEMENTS Alanine Arginine Ascorbic acid Aspartic acid Biotin Calcium carbonate Calcium citrate Calcium glycerophosphate Calcium oxide Calcium pantothenate Calcium phosphate Calcium pyrophosphate Calcium sulfate Carotene Choline bitartrate Choline chloride Chopper gluconate Cuprous iodide Cysteine Cystine Ferric phosphate Ferric pyrophosphate Ferric sodium pyrophosphate Ferrous gluconate Ferrous lactate Ferrous sulfate Glycine Histidine Inositol Iron, reduced Isoleucine Leucine Linoleic acid Lysine Magnesium oxide Magnesium phosphate Magnesium sulfate Manganese chloride Manganese citrate Manganese gluconate Manganese glycerophosphate Manganese hypophosphite Manganese sulfate Manganous oxide Mannitol Methionine Methionine hydroxy analogue Niacin Niacinamide d-pantothenyl alcohol Phenylalanine Potassium chloride Potassium glycerophosphate Potassium iodide Proline Pyridoxine hydrochloride Riboflavin Riboflavin-5-phosphate Serine Sodium pantothenate Sodium phosphate Sorbitol Thiamine hydrochloride Thiamine mononitrate Threonine Tocopherols Tocopherol acetate Tryptophane Tyrosine Valine (continued) TABLE 1 (continued) Additives listed by the U.S. Food and Drug Administration as “generally recognized as safe.” (Courtesy, Scientific American ) © 2006 by Taylor & Francis Group, LLC 274 EFFECTS OF CHEMICALS Vitamin A Vitamin A acetate Vitamin A palmitate Vitamin B 12 Vitamin D 2 Vitamin D 3 Zinc sulfate Zinc gluconate Zinc chloride Zinc oxide Zinc stearate SEQUESTRANTS Calcium acetate Calcium chloride Calcium citrate Calcium diacetate Calcium gluconate Calcium hexametaphosphate Calcium phosphate monobasic Calcium phytate Citric acid Dipotassium phosphate Disodium phosphate Isopropyl citrate Monoisopropyl citrate Potassium citrate Sodium acid phosphate Sodium citrate Sodium diacetate Sodium gluconate Sodium hexametaphosphate Sodium metaphosphate Sodium phosphate Sodium potassium tartrate Sodium pyrophosphate Sodium pyrophosphate, tetra Sodium thiosulfate Sodium tripolyphosphate Stearyl citrate Tartaric acid STABILIZERS Acacia (gum arabic) Agar-agar Ammonium alginate Calcium alginate Carob bean gum Chrondrus extract Ghatti gum Guar gum Potassium alginate Sodium alginate Sterculoia (or karaya) gum Tragacanth MISCELLANEOUS ADDITIVES Acetic acid Adipic acid Aluminum ammonium sulfate Aluminum potassium sulfate Aluminum sodium sulfate Aluminum sulfate Ammonium bicarbonate Ammonium carbonate Ammonium hydroxide Ammonium phosphate Ammonium sulfate Beeswax Bentonite Butane Caffeine Calcium carbonate Calcium chloride Calcium citrate Calcium gluconate Calcium hydroxide Calcium lactate Calcium oxide Calcium phosphate Caramel Carbon dioxide Carnauba wax Citric acid Dextrans Ethyl formate Glutamic acid (continued) TABLE 1 (continued) Additives listed by the U.S. Food and Drug Administration as “generally recognized as safe.” (Courtesy, Scientific American ) © 2006 by Taylor & Francis Group, LLC EFFECTS OF CHEMICALS 275 Glutamic acid hydrochloride Glycerin Glyceryl monostearate Helium Hydrochloric acid Hydrogen peroxide Lactic acid Lecithin Magnesium carbonate Magnesium hydroxide Magnesium oxide Magnesium stearate Malic acid Methylcellulose Monoammonium glutamate Monopotassium glutamate Nitrogen Nitrous oxide Papain Phosphoric acid Potassium acid tartrate Potassium bicarbonate Potassium carbonate Potassium citrate Potassium hydroxide Potassium sulfate Propane Propylene glycol Rennet Silica aerogel Sodium acetate Sodium acid pyrophosphate Sodium aluminum phosphate Sodium bicarbonate Sodium carbonate Sodium citrate Sodium carboxymethylcellulose Sodium caseinate Sodium citrate Sodium hydroxide Sodium pectinate Sodium phosphate Sodium potassium tartrate Sodium sesquicarbonate Sodium tripolyphosphate Succinic acid Sulfuric acid Tartaric acid Triacetin Triethyl citrate SYNTHETIC FLAVORING SUBSTANCES Acetaldehyde Acetoin Aconitic acid Anethole Benzaldehyde N-butyric acid d- or l-carvone Cinnamaldehyde Citral Decanal Diacetyl Ethyl acetate Ethyl butyrate Ethyl vanillin Eugenol Geraniol Geranyl acetate Glycerol tributyrate Limonene Linalool Linalyl acetate 1-malic acid Methyl anthranilate 3-Methyl-3-phenyl glycidic acid ethyl ester Piperonal Vanillin TABLE 1 (continued) Additives listed by the U.S. Food and Drug Administration as “generally recognized as safe.” (Courtesy, Scientific American ) © 2006 by Taylor & Francis Group, LLC 276 EFFECTS OF CHEMICALS The Delaney Amendment, dealing with food additives, has been in place since 1958. A substance which produced cancer in laboratory animals could not be used as a food additive. It was overhauled significantly in 1996. More foods are now covered. However, states cannot set standards which are more strict than the federal rules. The standard for pes- ticides in raw and processed food is based on the amount which may be expected to produce cancer in one person in a million. It is estimated that there are as many as 1400 natural and synthetic flavors available today. Increased use of flavoring has paralleled the introduction of new food processing and distribution techniques. Flavor enhancers are closely related to flavors. The best known of these is monosodium glutamate (MSG). There is evidence linking excessive intake of MSG to Kwok’s dis- ease, sometimes known as “Chinese restaurant syndrome.” Symptoms include a tightening of the neck and face mus- cles, at times accompanied by nausea, headache, and gid- diness. Some countries have placed limits on the amount of MSG in foods and require that the presence of this substance be prominently noted. Color additives are utilized primarily for the purpose of giving an appetizing appearance to food. Synthetic dyestuffs are used much more often than natural materials. It can be expected that the synthetic dyes will be produced in a high state of purity. In general, small amounts of dye will suffice to give the desired food color. A material that gives a color that is durable is needed by the food processor. Regulations governing the colors that may be added to foods vary mark- edly from country to country and this causes some difficul- ties for food processors engaged in international operations. Some commonly used preservatives are benzoic acid, sodium benzoate, sorbic acid, monosodium phosphate, sodium propionate, and sulfur dioxide. Of special interest is the use of sulfur dioxide for inhibition of mold and discol- oration in wine. Sulfur dioxide is, of course, a prominent air pollutant. There is anxiety that the acceptable daily intake of sulfur dioxide will be exceeded in countries where wine intake is heavy. Experimental evidence indicates that sulfur dioxide inhibits the growth rate, probably due to destruction of Vitamin B 1 by sulfite. Antioxidants, added to prevent rancidity in fatty foods, can be put in the classification of preservatives. A second use for antioxidants is developing with the growing prac- tice of display of food in transparent containers and wrap- ping. Attendant exposure to light causes discoloration, not necessarily detrimental to nutritional value in itself, but detracting from attractiveness. The most commonly used anti- oxidants are butylated hydroxyanisole, butylated hydroxy- toluene, propyl, octyl and dodecyl gallates, and tocopherols. Antioxidant effect of a substance can often be increased by addition of a second material, producing a synergistic reac- tion and allowing more effective product control. Texture agents include emulsifiers, stabilizers, and thick- eners. These are the largest single class in terms of total quan- tity consumed in food. Use of these agents has contributed greatly to the development of the new convenience foods. The miscellaneous group includes acids, alkalies, buf- fers, neutralizing agents, anti-glazers, release agents, anti- caking materials, clarifying agents, and foaming agents. All of these substances are primarily manufacturing and pro- cessing aids. Indeed, without many of these materials the range of modern foods would be much more limited. Testing of food additives as with most other chemicals, is not usually done with human subjects. Exposure studies of both limited duration and long term are made on mice, rats, dogs, and other laboratory animals. When deviation from normal response is noted, the largest dosage that does not produce the change is used as the base for acceptable intake for humans. Normally, this dosage is reduced by a factor of about 100 in most countries. The allowable, or accept- able, dosage is expressed as milligrams of the substance per kilogram of receptor body weight. It must be emphasized that extrapolation from animals to humans is always a dif- ficult undertaking. International guidelines have been issued by the World Health Organization and the Joint Expert Committee on Food Additives of the Food and Agriculture Organization. The Codex Alimentarius Commission of the Food and Agriculture Organization has published six principles con- cerning the use of food additives. 1) The use of an additive is justified only when it has the purpose of maintaining a food’s nutritional quality, enhancing keeping quality or stability, making the food attractive, providing aid in pro- cessing, packing, transporting or storing food or providing essential components for food in special diets. An additive is not justified if the proposed level of use constitutes a hazard to the consum- er’s health, if the additive causes a substantial reduction in the nutritive value of the food, if it disguises faulty quality or the use of processing and handling techniques which are not allowed, it deceives the customer or if the desired effect can be achieved by other manufacturing processes that are economically and technologically satisfactory. 2) The amount of additive should not exceed the level reasonably required to attain the desired effect under good manufacturing conditions. 3) Additives should conform to an approved standard of purity. 4) All additives in use, or proposed, should be sub- jected to adequate toxicological evaluation and permitted additives should be kept under observa- tion for deleterious effects. 5) Approval of additives should be limited to spe- cific foods or specific purposes and under specific conditions. 6) Use of additives in foods consumed mainly by special groups within the community should be determined by the food intake of that group. Toxicity is the general term applied to adverse biologi- cal effects in man resulting from pollutants. Effects may © 2006 by Taylor & Francis Group, LLC EFFECTS OF CHEMICALS 277 range from lessened health levels to death. Chronic toxicity is of major interest here. Included under effects of chornic toxicity are carcinogenicity, teratogenicity, and mutagenic- ity. It has been suggested that some behavioral disorders are seated in the effect of toxic substances. This area has not been extensively investigated. One or more of these types of toxicity may be induced by pollutants in the environment. Pollutants may cause adverse effects alone or may interact synergistically with ordinarily harmless substances to give unexpected results. The mecha- nism of smog formation is an excellent example, although Man is but indirectly affected. It has been estimated that, over the expected life span of one malformed child, the total costs for care are in the neigh- borhood of a million dollars. This figure, which does not include loss of earnings, is a high price for society to pay. Widespread, long-term genetic effects due to environ- mental pollution cannot be accurately predicted but the cost is certainly great. Such cost estimates have not, until recently, been applied in matching benefits to cost in evaluation of a potentially hazardous substance. Hazards from a particular substance need not be accepted when another substance of equal worth is available. Mandatory testing is usually looked upon as an unnecessarily bothersome expense by producers of synthetic substances. In fairness, however, it must be said that some chemicals, in use for years, have been unexpect- edly indicated as potential hazards and the economic loss has been heavy. Cyclamates are a good example. It is of interest to speculate if such a situation could have been avoided. The basic question concerns the adequacy of existing legislation and difficulty of implementing regulations. It has become increasingly clear that many diseases formerly regarded as spontaneous are caused by environmen- tal pollutants. These diseases include cancer, birth defects, and mutations. The problem is compounded by greatly increased exposure of the population to new synthetic chem- icals and their degradation products. Environmental effects of these substances are not usually adequately evaluated. There is now overwhelming evidence that many human cancers are due to carcinogenic substances in the environ- ment. These are, then, preventable. Studies of epidemio- logical factors have indicated strongly local environmental factors are of significance in cancer incidence. There is a demonstrable link between cigarette smok- ing and lung cancer and other cancers have been shown to be related to smoking. Cigarette, pipe and cigar smoking have become socially unacceptable. Ayers has described the cigarette as a private air pollution source. There is strong evidence that effects of smoking are experienced by persons in the vicinity of the smoker. Environmental tobacco smoke can be defined as a mixture of sidestream smoke from the cigarette and mainstream smoke exhaled by the smoker. Smoking in schools, public buildings and businesses is now widely banned. In 1604 James I described smoking as “A custom loath- some to the eye, hateful to the nose, harmful to the brain, dangerous to the lungs.” The first major paper suggesting a link between smoking and lung cancer was published in 1939. In 1950 Wynder and Graham reported that, in a group of 650 men with ling cancer, 95% had smoked for at least 25 years. Doll and Bradford, in a 1951 report of inter- views with 1357 patients with lung cancer, found that 99.5% were smokers. There was a marked decrease of cigratte smok- ing after the 1963 Report of the Surgeon General of the US Public Health Service. In the same year, an internal document of a major tobacco company stated that the company was in the business of selling nicotine, an addictive drug effective in release of stress mechanisms. The British government banned television advertising of cigarettes in 1965. The first health warnings appeared on American cigarette packs in 1966 and on British packs in 1971. A 1984 review article in the Journal of Epidemiology confirmed the link between smoking and cervical cancer. A 1990 study related lung cancer in nonsmok- ers to passive childhood smoking. A former Prime Minister accepted a contract in 1992 with a tobacco company as an adviser on strategy for selling cigarettes in Eastern Europe and Developing Nations. In 1993 the US Environmental Protection Agency classified environmental tobacco smoke as a Class A carcinogen. The State of Texas, in a 1996 suit against a ciga- rette maker, quotes a company executive as saying “We don’t smoke the—, we just sell it. We reserve that for the young, the black, the poor and the stupid.” President Clinton, the first US President to engage in open conflict with the tobacco industry, declared tobacco to be an addictive drug. While Legal Aid to fund claims against tobacco com- panies by former smokers was refused in the UK in 1996, lawsuits against tobacco companies in the United States have been filed by individuals and as class actions. 22 states have sued tobacco companies to regain vast sums of public money expended on care for smoking related maladies. Previously confidential documents from company files and information supplied by whisle-blowers have shown that the companies were aware of adverse health effects of smoking as early as the 1930s. The tobacco industry, faced with decreasing usage at home, resorted to a creative marketing approach. It was decided that a new market must be developed. One large tobacco company targeted black people and young, blue- collar females. There was a strong public outcry when this was reported in the news media and the company withdrew the campaign. It was a public relations disaster. There is increased effort to market American cigarettes in the Third World. American tobacco products enjoy a good reputation as to taste and are popular overseas. Officials in some developing countries have accused the US of follow- ing a double standard with regard to addictive drugs at home while promoting cigarette use abroad. Cancer of the oral cavity in Asia is linked with chewing of tobacco leaves and betel nuts. High incidence of gastric cancer in Chile, Iceland, and Japan has been associated epi- demiologically with a diet high in fish. It has been suggested that nitrosamines, formed by reaction between nitrites and secondary amines of the fish, may be a significant factor. Nitrites are employed as a preservative of fish. Dietary con- tamination with aflatoxin is thought to be a causitive effect of liver cancer in the Bantu. Aflatoxin is a fungal carcinogen. © 2006 by Taylor & Francis Group, LLC 278 EFFECTS OF CHEMICALS Ingestion of azoglucoside carcinogens with Cycad plants is probably the chief cause of liver cancer in Guam. Cancer of the esophagus in Zambians may be related to high nitrosa- mine content of Kachasu spirits. There is well documented evidence of occupationally related cancers. These include bladder cancer in the rubber and aniline dye industries, lung cancer in uranium workers, nasal sinus cancer in wood workers, skin cancer in shale oil workers, and lung cancer in asbestos workers. The question of asbestos assumed great importance in the 1980s. Once widely used in building, it was found to be a serious health hazard. It is now felt that no exposure to airborne particles is safe. The Environmental Protection Agency estimates that 30,000,000 tons were used between 1900 and 1980. Asbestos abatement has become big business. One estimate places the value as high as $200 billion per year. Asbestos has been used in more than 3000 products over the years. These include duct work, exterior shingles, floor and ceiling tiles, plaster, pipe lagging, cement, drywalls, theater curtains, brake lin- ings, clutch facings and baby powder. Asbestos occurs naturally as chrysotile, crocidolite, amosite, anthophyllite, actinolite tremolite. The thin, tiny fibers are not dangerous until disturbed. Then particles of a certain size can lodge in the lungs. When the substance can be crumbled under hand pressure—friable—it is considered extremely dangerous. Building renovation and demolition can release particles into the air. Water damage can loosen the binding matrix. In the 1930s asbestos inhalation was linked to asbesto- sis and lung cancer. It was later shown that mesothelioma, cancer of the lining of the lung, is caused by asbestos. Gastrointestinal and larynx cancers have also been asso- ciated with asbestos. In the 1970s the Department of Health, Education and Welfare estimated that 8 1/2 to 11 million workers have been exposed occupationally in the last 40 years. Asbestos related illnesses can take 20 to 40 years to develop. World War II shipyard workers and prewar insulation workers comprise the majority of afflicted persons. In one study a premature death rate of 48% was found among insulation workers of the 1940s. Custodial personnel are also thought to be at high risk. Studies have found that wives of asbestos workers may well be in danger. It is thought that fibers on the husbands’ clothes are the reason. Asbestos fibers suspended in water are not thought to pose a hazard. However, steam pipe explosions have put fibers into the air, causing whole blocks to be evacuated and necessitating expensive cleanup operations. Some claims that chrysotile, the asbestos form most com- monly used in the US, may pose less danger than other vari- eties. This position has not yet been validated scientifically. The variety of asbestos versus fiber size as more important in causing disease is the current debate topic. Some European nations and Canada make distinctions among asbestos vari- eties but, in the US, the EPA and OSHA treat all forms the same for rule making purpose. The UK and Scandinavia follow closely the US approach. Considerable uncertainty exists in risk assessment for nonoccupational and environmental settings. Action on asbestos abatement began in the schools. Since the period for appearance of asbestos related diseases can be as long as 20 to 40 years, it was felt that school-age children were at particular risk. In 1982 the EPA Asbestos- in-Schools required all public and private schools to inspect for friable asbestos and report to parents and employees if any were found. The rule did not require abatement. In 1984 the Asbestos Hazard Abatement Act gave funds to assist in abatement. The Asbestos Hazard Emergency Response Act (AHERA) of 1986 established rules and regulations concern- ing identification, evaluation and control of asbestos contain- ing materials in schools. It further required schools to identify friable and nonfriable asbestos found and submit manage- ment plans to state governors. Provisions were included for periodic reinspections, even though inspections were already made as a result of the notification rule of 1982. Of great importance was that portion of the Act dealing with removal situations and certification of workers. In the early days of removal, when guidelines were not yet available, there were too many “rip and skip” operators who performed such work without regard for proper procedures or air quality monitor- ing. In many cases there was probably more asbestos in the air after the operation than there was before. It is felt that asbestos abatement in private homes will not be covered by formal regulations. However, it is esti- mated that about 75,000 commercial and industrial buildings contain friable asbestos. There are four basic abatement approaches. 1) Removal 2) Encapsulation, in which friable asbestos is bound in a matrix. 3) Isolation of the asbestos containing area 4) Repair All of these means have a place in dealing with the asbestos problem and it is necessary to seek advice of a qual- ified professional before undertaking any action. It should be noted that, in the early days of abatement efforts, some education departments allowed only removal. Encapsulation was forbidden. In retrospect, this inflexible position might be criticized. The National Institute of Building Sciences (NIBS) has taken the position that there is no single correct answer for all situations. Environmental carcinogens can be classed into two categories, potent and weak. Potent carcinogens, such as nitrosamines and aflatoxins, can induce cancers in animals in very low concentrations. Isolation of these substances in food has given rise to endeavors to relate food distribution patterns with local cancer incidence. Weak carcinogens, such as atmospheric pollutants, some pesticides, and food additives, have effects much more difficult to evaluate and thus may pose as great a threat as the potent carcinogens because they are less likely to be recognized as a significant epidemiological factor. Often, © 2006 by Taylor & Francis Group, LLC EFFECTS OF CHEMICALS 279 evaluation must be by indirect means. A causal relationship has been demonstrated to exist between urban air pollution and lung cancer. Lung cancer mortality patterns differ in various sections of the United States and Great Britain. It has been clearly shown that increased mortality due to lung cancer is related to increased urbanization. A survey in the late 1950s found lung cancer rates in the United States to be 39 per one hundred thousand in rural areas and 52 per one hundred thousand in urban areas. Similar data were gath- ered in Great Britain and the added effect of smoking was evaluated. The conclusion of significance of urban air pol- lution is inescapable. The first demonstration that environmental pollutants can cause genetic damage came with the discovery that high energy radiation induces mutations. Later, the devel- opment of the nuclear industry focused increased attention on the dangers of unwanted genetic change. Associated with possible genetic damage in this industry was the danger of radiation induced carcinoma. Accordingly, safeguards were developed and limits were set on radiation levels. These were functions of exposure time. Limits were changed peri- odically in the light of fresh evidence. It is of interest to note that changes were usually downward. Radiation from X-Ray machines and fluoroscopes was treated in the same way. A widely available hazard was the fluoroscope for fit- ting of shoes. It is impossible to determine possible genetic damage from this source but it was probably considerable. Such installations have all but disappeared. Medical and dental radiation sources are firmly regulated. There was sus- picion that some chemicals might induce mutations but only about thirty years ago was the mutagenic effect of mustard gas on fruit flies shown. There is concern in some circles that strongly mutagenic chemicals, their effects not yet rec- ognized, may already be in wide use. A mutation can be a chemical transformation of a single gene or a rearrangement of a chromosome. The former, called a gene or point mutation, can cause an alteration in function. The latter may be microscopically visible and is known as chromosome aberration. In studies of human subjects the aforementioned changes are not always easily determined. When genetic function of a cell is changed while repro- ductive capacity is unaltered the genetic change is transmit- ted to descendant cells. Mutations in germ cells are most serious in long-term effects because changes are transmitted to future generations. Mutagenic effects are of many types. These range from lethal effects to changes so slight as to remain unnoticed. It is thought that many inherited diseases are based in muta- genic effects. At this time there is no known way to ade- quately evaluate long-term mutagenic effects. It is a cause for serious concern for future generations. Genetic effects over a long term are statistical rather than discrete. As natu- ral selection has had its effect over a long period, so will externally induced mutations make their effect felt over a long period. Dominant mutations appear in the next genera- tion while recessive mutations require contributions from both parents. This characteristic may not appear for many generations. Most mutations are harmful or neutral. Many mutants which in the past would have produced death or lessened fertility now remain. This is due to higher standards of health care. The former equilibrium, in which old mutations disap- peared about as rapidly as new mutants appeared, has been upset in favor of new mutants. Natural selection does not apply as strongly as before. It has been suggested that medi- cal problems of the future will be more and more due to genetic origin. One estimate places our present health burden as being 25% of genetic nature. If a mutation causes a gene to have a sterilizing or lethal effect, only one generation is involved. Less severe effects, however, may involve many generations. The less severe the effect, the more people will be exposed. Mild mutational effects, affecting many people, will have a greater public health impact than one severe, or fatal, case. Unfortunately, many of these milder effects may be difficult to detect. Many chemical mutagens in the environment pose threats which have not yet been adequately evaluated. Mammalians test systems are available but extrapolation from smaller ani- mals to man is indeed difficult and liable to error. Trimethylphosphate, until recently, was added to gaso- line for control of surface ignition and spark plug fouling. This substance has been implicated in chromosome damage in rats. The dosage in rats at which damage occurred was at subtoxic level. However, extrapolation of dosage levels to man is difficult and man’s exposure to the substance in the environment is almost impossible to estimate. Congenital malformations are those abnormalities which can be recognized at birth or shortly thereafter. The study of these abnormalities, which can cause serious disability or death, is known as teratology. A broader definition can include microscopial, biochemical, and functional abnor- malities of prenatal origin. It is estimated that about 3% of live births involve congenital malformations, but this is only an estimate. Lack of adequate data at the national level makes such figures rather rough and probably inaccurate. Three categories of human teratogens have been identi- fied. These are: (1) viral infections, (2) ionizing radiation, and (3) chemicals. Thalidomide is the best known of the third category. Experimental evidence of teratogenicity of some compounds had been in existence for many years but requirements of three generation reproductive tests in ani- mals were established only after the sensational thalidomide disaster of 1962. Some questions concerning the validity of such tests have been raised. Pollutant materials to which humans are exposed must be examined for toxicity. These examinations must also include specific tests for carcinogenicity, mutagenicity, and teratogenicity. These effects have been studied in the past by separate disciplines and there has been inadequate inter- change of results and ideas. It is to be hoped that the emerg- ing profession of environmental scientist will aid in breaking down these historical and somewhat artifical barriers among disciplines. There is need for more sensitive and reliable methods of testing effects of single chemicals, degradation products and mixtures. External environmental effects must also be © 2006 by Taylor & Francis Group, LLC 280 EFFECTS OF CHEMICALS included as system parameters in evaluation of pollutant effects. It is possible that human tests may become necessary, but moral and legal considerations pose serious questions. Agents under test must be administered at subtoxic, toxic, and chronic levels. Effects of possibly significant but normally non-toxic agents on the system containing the toxic agent under investigation must also be evaluated. Testing procedures must be realistic and reflect the path- ways of human exposure. However, the exception to this rule is in sensitivity. Evaluation of carcinogenic effect may require administration to test animals by different means. Normal ingestion in humans might be by inhalation while adequate dosage in rats might require addition of the sub- stance in question to daily food. This is particularly true when dealing with weak environmental carcinogens. Metabolic compatibility between a test species and humans is important for extrapolations of test results. There is seldom a one to one correspondence and most authori- ties feel that at least two test species should be examined. There is much testing data on rodents, pigs, and subhuman primates. Thus, further utilization of these animals is indi- cated. In special cases, however, a less common species may be necessary in order to gain the desired data. It is necessary to test levels much higher than human exposure for carcinogenic, teratogenic, and mutagenic sub- stances. It must be noted that, even when large numbers of mice are tested, the number is still small compared to the millions of humans that might be exposed in the everyday environment. Not all humans exposed would respond, in any event, to the dangerous substance. As an example, meclizine, an antihistamine used for treatment of morning sickness, has been found to be teratogenic in the rat but not so in a relatively small number of women tested. The question as to effects on a larger population is unanswered. For thalidomide, humans are found to be 60 times more sensitive than mice, 100 times more sensitive than rats, 200 times more sensitive than dogs, and 700 times more sensitive than hamsters. It is obvious, therefore, that predictions as to teratogenic doses of thalido- mide on the basis of animal testing would mean very high and dangerous exposure levels. Complicating the testing picture is the increased effect of substances when a second, supposedly innocuous, substance greatly increases the undesirable end effect. Such reactions were the basis of the Delaney Amendment of 1968 to the Food, Drug, and Cosmetic Act (US). The Amendment required that no additive be considered safe if found, under appropriate testing conditions, to induce cancer in man or animal. Recent advances in molecular biology have made it pos- sible to give weight to a broad range of evidence, including details as how toxic agents affect human cells and on genetic material which controls cell reproduction. The relatively new concept of virtual risk may find application. It should be noted, however, that use of cost/benefit may not be desir- able and should be treated with caution, if not suspicion. At times this concept has been used to evade existing environ- mental regulations. Elected officials are finding that efforts to weaken public health and pollution control legislation are unpopular. Often, non-carcinogenic alternatives are available as replacements for questionable materials. There is consider- able controversy about the pesticide DDT. Some authorities question the continued utility of DDT for control of cotton insects due to development of resistant strains. This contro- versy will not soon die down. Cyclamates, banned in recent years, were an intentional food additive and of no value nutritionally. Only after their widespread use for a number of years was there shown a carcinogenic danger. The argument of economic loss to special interest groups is of no validity. In view of the uncertainty of long-term effects of carcinogenic materials, zero tolerance levels must be imposed for these substances. It is important that chemicals, and their derivatives, suspected or implicated as toxic, carcinogenic, teratogenic, and mutagenic be detected and monitored in the environ- ment. Epidemiological studies may show effects but it is necessary to quantitively establish occurrence of these sub- stances. It has been possible to demonstrate the relationship between cigarette smoking and lung cancer although some special interest groups seriously disputed this. However, in this case were two dissimilar populations, smokers and non-smokers. In the case of exposure of the general popu- lation to a suspect substance, evaluation and epidemiologi- cal treatment of data are more difficult. Apart from rubella virus, no known teratogens, such as ionizing radiation, mercury, etc. have been positively identified epidemiologi- cally in the highly industrialized countries. This indicates the great need for better and more comprehensive gather- ing of data relating to birth defects. It is to be hoped that environmental effects should be segregated from natural and spontaneous mutation effects. It would be necessary to monitor special indicator traits. Such traits would have to be chosen with great care and followed for a considerable period. Recently it has been suggested that mutation rates could be monitored by means of data on spontaneous abor- tions. Teratogens may cause chromasome aberrations but these act after fertilization and would be against a normal background. The question of data on occupational hazards, long the major field of endeavor of the industrial hygienist, must be raised in connection with legislation thought to be inade- quate and outdated. The correctness of much of the informa- tion on which maximum allowable concentrations are based is in doubt at this time. Probably a critical reexamination will soon come about as a result of increased environmental awareness. Present toxicological techniques are not sufficiently sensitive to monitor adequately many weak carcinogens. Compounding the problem is the difficulty of recognizing effects of many substances in the general population. Special situations as to sample population at times help to simplify the problem, such as cigarette smoking. But there is cer- tainly a great area in which problems are strongly suspected to exist but statistical validation is not possible at this time. Yet tolerance and allowable concentration limits must be set. There is a most fruitful area for research here. © 2006 by Taylor & Francis Group, LLC [...]... Pollution, 2nd Ed., Wiley-Interscience, New York, 1972 Ferrand, E.F., Effects of Air Pollutants, The Encyclopedia of Environmental Science and Engineering, 4th Ed., Gordon and Breach Science Publishers, New York 1998 Glasser, M., L Greenburg and F Field, Arch Environ Health, 15, 684, 1971 Heuss et al., J A P C A., 541, 1971 Hopkins, E.S and W Schulze, The Practice of Sanitation, Williams and Wilkins, Baltimore,... of the Surgeon General, 1981 Report of the Surgeon General, 1989 Rouche, B Eleven Blue Men, Little, Brown and Co., New York, 1953 Salvato, J., Environmental Health, The Encyclopedia of Environmental Science and Engineering, 4th Ed., Gordon and Breach Science Publishers, N.Y., 1998 Walker, R.S., The Quest for Knowledge versus the Quest for Votes, IEEE Technology and Society Magazine, Spring 1997 PAUL... saved and the health effects can be cumulative Public health practice is the basis of the great majority of environmental efforts REFERENCES Adams, J., Virtual Risk and the Management of Uncertainty Paper presented at the Royal Society Conference on Science, Policy and Risk London March 18, 1997 Anon., Minimata Case Is Settled Decades Later Chemical Engineering, p 46, June 1996 Anon., New Standards... Preventive Medicine and Public Health, 8th Ed., Appleton-Century-Crofts, New York, 1956 Needleman, H.L and P.J Landrigan, Toxins at the Pump, N.Y Times, March 13th, 1996 Oberle, M.W., Science, 165, 991, 1969 Perlman, M.E et al., Pediatrics, 47, 391, 1971 Policy Making, Department of Trade and Industry, London, March 18, 1997 Proctor, R.N., Cancer Wars, Basic Books, New York, 1995 Report of the Surgeon General,.. .EFFECTS OF CHEMICALS Regulatory agencies are often understaffed and underfunded Attention of existing resources is usually allocated on the “squeaky wheel” principle They move from current crisis to current crisis and are frequently unable to devote enough time to prevention of new crises This is contrary to good public health practice At... Junge, C.E., Air Chemistry and Radioactivity, Academic Press, New York, 1963 Karaffa, M.A et al., Evaluation of Asbestos Levels in Two Schools Before and After Asbestos Removal, EPA/600/5 2-8 9/010, Environmental Protection Agency, Washington, D.C., 1989 Kendall, D.M., A Summary of Panel Recommendations: Report of a Panel on Food Safety to the White House Conference on Food, Nutrition and Health, Washington,... Generals, Dr C Everett Koop, was also the most outspoken about the dangers of tobacco use He became something of a folk hero and was highly respected There have been some instances where persons not in sympathy with environmental control and public health have been appointed to high positions in environmental protection The need for environmental protection does not change with political climate Efforts... responsible officials In the Report of the Surgeon General (1981) it was stressed that smoking, particularly cigarette smoking, can cause many types of cancers However, the Surgeon General declined to take issue with the continued granting of subsidies to tobacco growers by noting that price supports are considered an economic and agricultural issue and not an issue concerning public health The most visible of. .. Chemical Engineering, p 25, August 1996 Ayers, S.M., Conference on Metropolitan Air Pollution, Wagner College, New York, 1967 Barth, D.S et al., J.A.P.C.A., 21, 544, 1971 © 2006 by Taylor & Francis Group, LLC 281 Brandt, A.D., Industrial Health Engineering, John Wiley and Sons, New York, 1947 Chiaramonte, J et al., N Y S J of Medicine, p 394, Feb 1970 Epstein, S.S., Nature, 228, 816, 1969 Faith, W.L and . Faith, W.L. and A.A. Atkisson, Air Pollution, 2nd Ed., Wiley-Interscience, New York, 1972. Ferrand, E.F., Effects of Air Pollutants, The Encyclopedia of Environmental Science and Engineering, . Blue Men, Little, Brown and Co., New York, 1953. Salvato, J., Environmental Health, The Encyclopedia of Environmental Sci- ence and Engineering, 4th Ed., Gordon and Breach Science Publishers, N.Y.,. additives, house- hold chemicals, industrial chemicals, therapeutic and pro- phylactic drugs, and drugs of abuse. Food additives may be intentional or accidental. Anti-oxidants and dyes are added