ENCYCLOPEDIA OF ENVIRONMENTAL SCIENCE AND ENGINEERING - EFFECTS OF CHEMICALS docx

There is some concern that irradiation of food may have adverse effects and leave unwanted residues.. Food additives have been classified by Kermode into five broad groups: In Table 1 a

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

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

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:

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, Scientific 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

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 )

Vitamin A

Vitamin A acetate

Vitamin A palmitate

Vitamin B12

Vitamin D2

Vitamin D3

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 )

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 )

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, 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 spespe-cific purposes and under spespe-cific 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

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

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

2) Encapsulation, in which friable asbestos is bound

in a matrix

3) Isolation of the asbestos containing area

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,

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 mutagenera-tions require contribugenera-tions 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 apdisap-peared, 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 breakemerg-ing 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

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 relatgather-ing 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 concentrainforma-tions 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