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Contents Introduction Lead: An Essential Metal Measurements m Man Society Creates Wastes How the Body Handles Inhaled Lead Atmospheric Lead Measurements Recent Research Fmdtngs Expanded Research Program References The color of thu <o\*r dupltcat$$ that of ttortd. or4 trod chromotf yellow potntt ut*4 t*ory* where tor traffic morki*$ mhd other tofetp 4ppli<etio*r. introduction Industry and government, together with medical and research science, are today joining in a new massive effort to team more about the myriad substances in the air around us and what they mean to our health and well being. Lead is one of those many substances. This basic element is present in the air in extremely small quantities, us ually in the form of inorganic salts. All studies conducted by government, university, or other research groups have shown that the levels of lead in the general or ambient air are low and do not constitute a health hazard. Nevertheless, certain pertinent ques tions have been raised and studied. How much lead is in the air? How do the concentrations vary from place to place and time to time? Where does it come from? Does it contribute to "smog" formation? How much lead does man breathe in? What happens to this? What proportion of lead in the general environment comes from the air? What part comes from li quids? From foods? What does re search science know about effects of lead on man? What effect docs lead, in the air or elsewhere, have on man? What researches are now being con ducted? These and other questions will be discussed in this booklet From existing research data and other information, it will be seen that lead in the air does not pose a problem for the public under present conditions or in the foreseeable future. Yet care ful attention is being given and will continue to be given to alt aspects of lead in the environment including air-borne lead. The Lead Industries Association is constantly seeking to develop, assem ble and disseminate factual informa tion on the many aspects of lead and its uses in society today and to pro vide guidance on proper safeguards to be exercised. This booklet on "Lead and the Atmosphere" is one in a series being issued by the Lead in dustries Association. Readers are re ferred to the booklet "Facts About Lead and Industrial Hygiene." lor a discussion of the control of lead in occupational exposures. An Essential Metal Lead is everywhere. In the soil, in the air. in the sea. ft is in the bodies of city dwellers and in the bodies of natives deep in New Guinea's wilds, one of the most remote areas in the world, thousands of miles from modem civilization. Lead is the basic ingredient in the solder that binds together our elec tronic miracles and is the sheath that protects our intercontinental com munication system. It is the barrier that confines dangerous x-rays and atomic radiation. It is sound-proofing for buildings and ships and jet planes. It is (he major component in the bat teries that stan our can and it is in the gasoline that runs our cars. It is an essential metal that is too com monly taken for granted by the pub lic. Because lead is widely and essentially used in modern civiliza tion, there has been scientific interest in watching trends of lead in the en vironment and in people. Several re- PNtC0C0026<*9 cent studies, both in the United States and in other countries, have confirmed that lead in the general at mosphere is at extremely low aver age levels, about one-hundredth of the concentrations sate for workers m lead industries. These studies also checked lead levels in people from several population groups and found no indication of increasing body bur dens oi lead in the general public. Some Pertinent Observations These studies will be discussed in greater detail m later sections, but the following observations are parti cularly pertinent: From the American Medical Associ ation's Committee on Occupational Toxicology (1966): "The Committee feels obliged to point out that as a result of years of careful clinical study in workers in the lead industry significant, subtle, and unrecognized or 'un recognizable' changes are not oc curring in the general population as a result of iis exposure to en vironmental lead. In fact, this vast clinical evidence, evaluated by a great number of clinically trained scientists, suggests that the general public is not now. nor in the im mediate future, facing a lead haz ard." (1) From the U S. Public Health Service publication. "Survey of Lead in the Atmosphere of Three Urban Com munities" (I96J): "Data from (air samplings) show no consistent trend in the concen trations of lead in the atmosphere of (he three cities during the past 5 years . . . (Blood lead levels) are well within (he presently accepted range of lead levels for humans and are not significant in terms of a threat of the occurrence of lead intoxication within the groups." (2) From the World Health Organization II96J): "There has been no increase in lead contamination in the last two de cades ... If there has been any change, it would appear that at present man is exposed on the whole to less lead in his environ ment than he was 20 years ago . . . There is however no cause for complacency ..." 0) Recognized Facts About Lead Lead in the ambient air would be of little interest and of no consequence if it were not for several recognized facts: People in general normally have small amounts of lead in their bod ies and each day they take in and excrete tiny amounts of lead they get from food, beverage and air. The body is in "lead balance" un less an individual is subjected to an unusually high exposure for a con tinued period of time. f-t) Over-exposure to lead can result in lead intoxication, or ptumbism. a condition which is becoming in creasingly rare, mainly because of the protective measures in leadproducing-and-using industries. where over-exposure is most likely to occur. Other than infrequent occupational exposure, cases of lead intoxication are rare and are considered accidental. (Cases of childhood lead intoxication occur chiefly among children in slum areas who sometimes eat leaded paint chips from old buildings. This type of abnormal situation does not involve air-borne lead and is being brought under control by two courses of action: Non-leaded paints are standard for building interiors, and urban renewal and rehabilitation programs are becom ing more widespread.) Lead panicles, in varying sizes and quantities, can get into the air from various sources, including natural soil disturbances, the burning of certain fuels, bunting of waste materials containing lead, some lead-using industries, and the com bustion of automobile gasoline. The majority of lead in the daily in take of man comes from food and drink, with a much smaller, percent age coming from the air. Studies have shown, however, that the actual quan tity of lead absorbed from the normal atmosphere is so small as to be v,f. tually undetectable and constitutes no hazard. The question therefore is not whether there is lead in the environment or in the air or tn people. The questions are whether the lead that is present is of any significance to the health or welfare of people, and whether there is any likelihood that an increase in lead exposure is possible and poten tially harmful. Fortunately, much authentic data exist to deal with these questions, and more research is in progress to in crease our present knowledge. Measurements . in Man Only in the past few decades has it been possible to obtain sound in formation about lead in man and about lead in (he environment. This is because of the development of the sensitive techniques of measurement and identification that are required to establish reliable information. Armed with the necessary technology. medical and research investigators are able to determine how much lead an average man takes in. how much he excretes, how much he retains in his bones and various organs, how much is in his blood and his urine. These latter two measurements--in blood and urine--are the critical in dicators because it has been shown that an increase of lead in the blood or urine signals an increased intake of lead in the body Irom some abnormal exposure. Industrial ex perience has shown that a massive in crease in intake is required to elevate blood levels significantly, because the fWXCOO00 body retains little of the lead taken in. It has also been found that re moval of an individual from such exposures will bring bis blood level back to a normal range. (51 As a re sult of increasing knowledge concern ing the effects of lead. and the use of proper controls in industry, there has been a marked decrease in the inci dence of industrial lead intoxications over the past 50 years. Data from Many Studies Careful studies over a long period have produced the following facts pertinent to further discussion of lead in the air: (4. 8) The normal person takes in. ex cretes and retains some of practi cally every known element in his eating, drinking and breathing. American adults take in an average of about 550 micrograms of lead daily and excrete this same amount through normal body functions: thus the body remains in what is called "lead balance." There is no increase in lead in the normal body with age. Most of the lead intake comes from food and drink: a very small per centage from air. Lead entering the body from the air ranges from about 15 to 90 micrograms per day. depending upon a number of factors, includ ing occupation, place of residence and type of lead in the air. Amount of lead in blood of the average person will range from a low of about 10 to a high of about SO micrograms of lead in 100 grams of blood. Most lead intoxication cases stud ied show a range from 150 to 800 micrograms of lead per 100 grams of blood, and the lowest blood lead level associated with illness has been put at SO micrograms. for either adults or children.. This lat ter figure is usually taken as an indication that lead levels are get ting too high. An increase in lead found in the urine is also an indication of greater intake of lead, indicating need for further checking, usually of the blood levels. The above facts have relevance in connection with studies which have measured the amount of lead in the atmosphere of American cities and in the blood of a number of selected population groups. Society Creates Wastes Since the beginning of time, both nature and man have sent gases and dusts into the air, which retains a remarkable facility for disposing of or dispersing them--most of the time, in most places. But this ancient prob lem has acquired a new intensity be cause of man's constant crowding into city areas, his demand Cor the products of modem industry, and his society's creating more wastes than it is now prepared to dispose of readily. Because man creates wastes in almost everything he does, the complexities of dealing with the problems of air. water, and solid waste pollution are being increasingly recognized. Efforts to control and reduce man made contributions to air pollution in (be United States are beginning to show results, according to data from the U. S. Department of Health, Edu cation and Welfare's National Air Sampling Network (NASN). which checks the air in some 200 stations located in different parts of the country. The latest reported figures show that there was a slight, though significant, decrease in the average levels of particulates in (he air measured from 1957 through 1965. (6) Also listed are some of the things found among the suspended particulates, including such metals as arsenic, chromium, copper, iron. lead, manganese, nickel, tin. titanium, vanadium, and zinc. Of lead, the NASN report said: "At most locations less than I Si of the particu late matter is lead." This indicates the relative quantitative role of lead in the overall air pollution picture. It has been demonstrated that lead has no role in the formation of photo chemical smog, which is one of the undesirable manifestations of air pol lution. l7) Neither NASN nor any other data show any general increase in atmo spheric lead in recent years. Currently, there is much interest in the fact that about 99 percent of the gasoline used in automobiles in this country con tains varying amounts of lead anti knock compounds. When combustion engines operate on leaded gasoline, some of die lead is exhausted into the air. Cars, of course, are not the only source. Others are: Lead-using in dustrial processes: burning of waste materials containing lead: lead smelt ing and refining; and burning of fos sil fuels. Also, some natural sources contribute to lead in the air. (8} Modern Gasolines Need Lead The use of lead is highly important to the efficient and economic production and consumption of the high octane fuels required by modern engines. Lead conserves the amount of crude petroleum required ta make the gasolines which assure smooth per formance of automotive engines and improve mileage. Despite continued research and the testing of many other substances, no other material has been found as effective. Lead anti-knock compounds were first added to automotive gasoline in 1925 as a climax to a long and in tensive search for ways to make a more efficient fuel that would elimin ate harmful engine knock. The public health aspects of the use of leaded gasoline were investigated, and a com mittee appointed by the V.S. Surgeon General reported in 1926 that no hazard to the public health was in dicated from the use of leaded gaso line. (9) A similar committee in England reported essentially the same in 1930. 00) PNVC000C2651 As a result of technological and eco nomic developments m the automo tive and petroleum industries, it was proposed tn 19}$ that the maximum amount of lead anti-knock additives used per gallon of gasoline be in creased from three milliliters (about a teaspoonfull per gallon to four mill iliters. The then L .S. Surgeon General named a committee to study the ques tion. and in 1959 this committee con curred in the increase. 111! However, the maximum is used in only a small amount of all gasolines, and the aver age amount of lead in U.S. gasoline in 1967 is around 2.5 milliliters per gallon. What happens to the lead in the auto mobile's gasoline depends largely on the driving pattern and speeds fol lowed. and the condition and design of the car's engine and exhaust sys tem. (12) During combustion of gasoline in the automobile engine, the lead anti knock compounds change ro inor ganic salts, part of which are discharged in the exhaust. In addition exceedingly small amounts of these lead alky! compounds in organic form may reach the atmosphere through the escape of fuel vapors. Still more are displaced from the tank during refueling, but these amounts are so small they almost defy meas urement in the air. (2) How the Body Handles Inhaled Lead ' Studies to determine the size and chemical composition of lead in the atmosphere have shown that a con siderable percentage of the lead ex hausted by automobiles settles quickly to the ground and is carried of! by water or sweepings. Since most of these partieles are non-sofubfe. those which go into water settle down rap idly and do not become waterborne, while others become part of the soil. Air disturbances, caused by winds, storms or autos, may stir up some of these particles from time to time. The finer particles become part of the part iculate matter in the ambient air. and are the ones to which people are most likely to be exposed. (13. 14. IS) However, man's breathing defense mechanisms prevent the majority of dust particles. whether carrying lead or not. from reaching or remaining in the lungs. Small dust particles ibelow 0.5 mi crons in size: 1 micron equals 1/1000 of a millimeter and is invisible) lend to remain suspended in the respired air and many are exhaled. Larger panicles are filtered out in the nose. Approximately 90 percent of panicles having an average size of 10 microns or larger are removed in the nasal air passages. (16) Still other particles are cleaned out by the respiratory system's network of cilia--fine, hair-iike structures which constantly sweep out the trachea (windpipe) and bronchi (air tubes) leading to the lungs. Any panicles (including lead) (hat do reach (he small air sacs in the lungs are partially removed by scavenger cells called phagocytes. These engulf the panicles and carry them to a mov ing mucous layer by which they are moved upward by the cilia to the mouth. The quantity of lead inhaled ranges from less than 15 to 90 micrograms per day (no doubt being closer to the lower figure, according to a long-time researcher in the field). (8) Of the lead inhaled from the air. about 4S percent is exhaled immediately. The lung clearance defense mechanisms cany another 4S percent of the total inhaled to the gastrointestinal tract for eventual elimination. The remain ing 10 percent is absorbed into the blood, according to data derived from a lung dynamics task group of the In ternational Commission for Radiation Protection. (23) 7hus. in considering the effect of lead in the air on man. the amount of lead found in the air has to be weighed against the amount that a man may actually breathe in. retain and absorb. This is very much less than the amounts in the air. Atmospheric Lead Measurements Measurements of atmospheric lead in cities during the past 20 years have shown low levels on the aver age and no definite trend upward or downward. In considering figures on lead in the ambient air, it should be noted that the present accepted safe level for in dustrial exposure to lead in air is 200 micrograms of lead per cubic meter of air measured over an eight-hour day. i.e.. when the air of workrooms contains regularly not more than 200 micrograms of inorganic lead per cubic meter of air, as measured by prescribed methods, cases of lead in toxication do not occur. (25) In Cincinnati. Ohio, reliable measure ments of lead in the air in different parts of the city have been made since 1946. These measurements showed a downward trend in the main residential and basic basin areas from 1946 to 1954. Since then they have stayed relatively steady at below two micrograms of lead per cubic meter of air. Lead concentrations in the com mercial area also show a downtrend from about four to two micrograms per cubic meter of air from 1955 to 1962. Reasons given for this decline since 1946 are the diminishing uses of solid 'fuel, better collection and removal of the dusts and smoke from indus trial operations, better enforcement of smoke-abatement laws, and changes in traffic flow and land use in the metropolitan area. 117) PNYC00002652 This decline took place during a period when there was about a two fold increase in the amount of motor fuel used in the Cincinnati (Hamilton County i area and a nearly doubling in the number of ears. During 1954-JJ an examination of lead-in-air data from 24 U.S. cities was made with the following ob servations; (17) In cities up to 2.000.000 population, relatively low lead concentrations from J.J ro 2 micrograms per cubic meter of air were found. In cities over 2.000,000 population, the ranges of lead concentrations and the average amounts of lead ran higher, with Los Angeles at an aver age (median) of five micrograms per cubic meter the highest. The Three Cities Survey A detailed report on an extensive pro gram of lead-in-air measurements in three major cities was published by the Public Health Servtce in 1965. (2) The cities were Los Angeles. Cincin nati and Philadelphia, and the report is commonly known as the "Three Cities Survey." The lead measurements were made from 3.400 samples collected from the atmosphere regularly over the course of a year <from June 1961 through May 1962) from 20 different sites in the three cities. The findings were summarized in the report as follows: ' l. The annual average concentration of lead in the atmosphere ranged from about 2 micrograms per cubic meter of air in the downtown and industrial area of Cincinnati, to about I in the outlying areas of that city. The values in corresponding areas in Philadelphia ranged from 3 to I, and in Los An geles from 2 to 2. "2. The average concentration of lead in all of the samples obtained in each city was 1.4 mierograrns per cubic merer in Cincinnati. 1.6 in Philadel phia. and 2.5 m Los Angeles. "3. The highest concentrations of lead were found in the air during autumn and winter. The highest seasonal con centrations of lead at any station was 2 4 micrograms per cubic meter in Cincinnati. 3.S in Philadelphia, and 4.1 in Los Angeles. "4. The highest monthly concentra tion of any site was 3.1 micrograms per cubic merer in Cincinnati (Octo ber), 4.4 in Philadelphia (October), and 6.4 in Los Angeles (December). "5. The highest concentration of lead in any one sample was 6.4 micrograms per cubic meter in Cincinnati. 7.6 in Philadelphia, and ! 1.4 in Los Angeles. "6. The mean concentration of lead found in heavy traffic ranged from about 14 micrograms per cubic meter on Cincinnati streets through approxi mately 25 on Los Angeles Freeways, to 44 in a vehicular tunnel." (Ed. note; This particular finding refers not to the regular monitoring work of the Three Cities survey but to special studies, using mobile samplers, in or near heavy traffic streams in Cin cinnati and Los Angeles, and to meas urements from another study done in Boston.) "7. The average content of lead in par ticulate matter for all samples was 1.7 percent in Cincinnati. 1.5 in Philadel phia. and 2.3 in Los Angeles. "8. Atmospheric lead concentrations varied during the day: highest concen trations occurred in the early morning. "The concentrations of lead found in the atmosphere in this study were con sistent with those obtained during the same period by the National Air Sam pling Network (NASN) of the Public Health Service. Data from the NASN show no consistent trend in the con centrations of lead in the atmospheres of the three cities during the past 5 yean. Data obtained by the Kettering Laboratory indicate that in Cincinnati the trend has been downward since 1946." Though these data showed no trends in accumulation of lead in the air or of lead levels that would affect the health of the public exposed to the air. it is significant that the report indi cates that such studies should be con tinued. saying that the results "have established a baseline for future inves tigations of these types." The study itself was prompted by a recommendation of the Surgeon Gen eral's committee, previously referred to. which in 1959 concurred in the in crease in the maximum lead content of gasoline. This committee recom mended that the Public Health Serv ice, in cooperation with industries, carry out: "... Studies to provide more defini tive data on levels and trends of at mospheric lead contamination in se lected urban areas and of the body burden of lead in selected population groups." (11) Recent Research Findings In accordance with the latter part of this recommendation from the Sur geon General's 1959 committee, the Three Cities Survey in Los Angeles. Cincinnati and Philadelphia involved analyses of blood of approximately 2.300 persons and the urine of nearly 1,700 males within the same groups. (2) The persons examined were selected from groups such as policemen on traffic beats, service station and garage workers, commuters to and from sub urbs as well as non-commuters, and some persons with chronic illnesses. The results of this study showed many gradations in lead levels but no exces sive levels of lead in the blood or urine of those examined. Among the findings reported were: No relationship was found between blood lead levels and age. In a group of selected chronic dis- PNTC00002653 ease patients afflicted with respira tory. kidney or bone conditions neither the range of values nor the mean lead concentrations in the blood or urine differed from the general population. These data showed neither unusually high nor low levels of lead in any of these diseased groups. Out of the 2.342 people studied. only 11 showed blood lead levels equal to or higher than 60 micro grams per 100 grams of blood, and these U were from groups which probably had an occupational ex posure to lead - garage mechanics, traffic policemen, aircraft workers, etc. "A few values in excess of 0.06 <60 micrograms) are to be expected in a large sample of individuals rep resenting a variety of exposures to lead." the report observed. (A sub sequent follow-up on 7 of the 11 who could be rechecked showed that the lead levels on second mea surement had fallen into the normal range.) Urine lead levels fell within the fairly narrow range that is defined as "normal." The mean blood lead levels re ported ranged from 11 micrograms i per 100 grams of blood) among suburban non-smokers in Phila delphia to 38 micrograms among garage mechanics in Cincinnati (checked previously in 1956). 'it is important to recognize that the differences between the lowest and highest of the groups, while rela tively large, are well within the presently accepted range of lead levels for humans and are not sig nificant in terms of a threat of the occurrence of lead intoxication within the groups." the Public Health Service report said. The mean concentration of blood lead in smokers was slightly higher than that of non-smoke/s. Lead levels in blood of women ran slightly lower than for males and the difference was "remarkably con sistent." No explanation for this was noted and the report suggests that special studies on this question "would be desirable." Differences in the lead levels in the blood among the various groups in cluded in the Three Cities Survey are indicated in the tabulation below: Mean Blood Lead Levels 10/Selected Subject Groups in Three Cities Survey! tin mtcroprams per 100 /rami ol blood! Lead in Vo. Blood So. Blood City and Sublect Group Subnets (Meant City and Subnet Group Subnets (Meant Los Angeles: Aircraft Employees male 291 female 87 Clocinnad Polieemen 19 smokers 17 non-smokers 107 25 1 23 Policemen Pasadena City Employees ma)t female 155 88 52 Philadelphia; Suburban male female 23 58 Commuter male female 43 Downtown Resident male female 66 40 Policemen 113 21 19 12 13 13 19 IS 24 18 26 Firemen smokers non-smokers 163 27 Post Office Employees smokers non-smokers 118 20 Health Department Employees 30 5 25 24 24 16 Other Studies on Lend The Three Cities Survey findings were consistent with other similar, though less ambitious, studies in the United States as well as in other parts of the world. In 1943 a study of 188 Mexican and United States subjects showed mean blood levels of 30 micrograms per 100 grams of blood and mean urine levels of 27 micrograms per liter of urine, f 18) In 1960, a study of 970 Americans in six large cities and one rural area gave these findings: the mean for urban blood samples was 20 micrograms of lead per 100 grams of blood as com pared to 14 micrograms for the rural blood samples. (19j Pertinent find ings from this study are summarized: PNYC00002654 Blood Lead Levels < In niierngrimii per I'pi e-aiut 01 bloodl Cm 'o Samples Mean Range Sew Orleans 130 22 5-50 Dallas 123 13 3-54 Denver 131 19 "50 Chicago 97 20 5-60 New York 1 12 20 4-53 Cincinnati 137 20 3-51 Rural 102 14 1-35 An earlier study in Switzerland is of relevance because it included mea surements ai two periods, one just alter the introduction of lead anti knock additives into Swiss commer cial gasoline, the other about six years later. 120> The results: Swiss Study: Blood Lead Levels Average Values Wicrogrontl lug) ptr 100 grams ot blood 1943-1910 1911-1910 uf pteplt i*t ptcplt Medical students Id i No abnormal lead exposure) 19 13 27 Garagepersonnel23 40 22 31 Thus, there was no change in lead con centrations in the blood during the first six years tollowing the introduc tion of leaded gasoline in Switzerland, i The slight decrease shown in the fig ures is not significant.) World Survey Findings The World Health Organization of the United Nations more recently sponsored an international task force study of blood and urine measure ments collected from 16 nations of the world. The findings (published July 1967). averaged by country, showed average lead content in blood trom a low of 7 micrograms per 100 milliliters of blood among urban Pe ruvians to a high ot 23 micrograms lor urban dwellers in Finland. Aver age levels by residence, including urban and rural, reported in micro grams of lead per 100 milliliters of blood, were: Finland 26; Yugoslavia 24; United Kingdom 23; New Guinea 22; New York City 21; Czechoslo vakia. Egypt and Japan 20: Chile and California 17: Ohio 16: Israel and Holland 15: Argentina 14: Italy 13: Poland 12: Sweden 10: and Peru 7. The aggregate average was 17. (21) According to Drs. Goldwater and Hoover of Columbia University, who reported the results of the WHO sur vey. these and other recent investiga tions of "the lead content in human blood do not differ greatly from those shown by older investigations during the past three decades." The Columbia scientists said that "the lead levels reported in the blood of the New Guinea aborigines are of partic ular interest in that these natives, liv ing in the hills of New Guinea, away from industrialization and motoriza tion. showed blood lead levels higher in range than urban and rural Califor nians. The mean figure of 22 micrograms per 100 milliliters of blood was higher than that of samples from 13 other localities, including California. Ohio and New York City. Mean levels from England. Yugoslavia and Fin land are slightly higher than the New Guinea mean." More detailed information from the doctor serving the New Guinea area revealed that the environment is com pletely non-industrial and free of gas oline fumes. "Cooking is done in uten sils made of unfinished bamboo tubes. Other domestic utensils are made mostly of wood. These observations serve to illustrate the difficulties in assuming a simple relationship be tween residence and body blood lead levels." From these studies and other exist ing data.'n is shown that the quanti ties of lead detected in the atmosphere are well below concentrations that would present health concern to the public, are not increasing in general. and arc not elevating the body bur dens of the general public. fn a recent review ot research on sources of lead entering the body, the ability of the body to achieve lead balance, and the overall toxicology ot lead, a leading toxicologist in Cali fornia summarized as follows: 122 > "It has been shown that the popula tion of the United States is m lead balance and the old causes ot acute and chronic lead intoxication have been reduced to very low levels by changes in technology. Lead body burdens of the population have been maintained ac the same level for the past 30 years regardless of the fact that there has been a 2.5-fold increase in the use of leaded gasoline. The bulk of the body burden of lead has been obtained via the food chain and not by inhalation from the environ ment. Although lead is present in the ambient air. only a smail percentage of the inhaled lead is in the correct particle size for pulmonary retention and even that fraction contributes only an extremely small amount to the body lead burden. Body defense mechanisms make it highly unlikely that environmental lead could induce chronic lead insult in the population. Greatly increased exposure to lead slowly increases the body burden but only at levels well above those en countered m the environmem. The supposed chronic intoxication from environmental contamination is a myth, not a fact." -a Expanded Research Program Intensive medical studies carried out over a long period of time have estab lished sound criteria for determining safe levels of lead as found in the diet, in industrial atmospheres and in man's system. According to known medical C00002655 pNt evidence, compiled from a variety of research in the laboratory and on ani mals and human beings, present levels of lead in the general environment do not present a public health problem. There remain questions about lead in relation to human beings that should be investigated. The lead industry, which has long promoted and sup ported such research, is expanding its efforts to study these questions. Re search studies into health aspects are included in the program of the Inter national Lead Zinc Research Organi zation. Ine. i JLZRO), with which the Lead industries Association is affili ated. 1LZRO is now stepping up its efforts concerning investigations into lead and human health. One research project of immediacy and peinence is seeking to determine the smallest amount of lead in air which man breathes that would have an effect on the possible accumulation ot lead in the blood. Problem of Ambient Air Standards The pertinence of such research re lates to efforts by some air pollution control authorities to set ambient air standards for certain substances which, in excess in the atmosphere, are considered pollutants. Setting such standards for lead at this time calls for guesswork, when what is needed is solid information based on scien tific research. As has been said, in in dustrial exposures, the accepted safe level for a working lifetime is 200 micrograms per cubic meter of air in the workroom based on an eight-hour day. live-day week. Obviously, this would not necessarily apply to air which people are breathing 24 hours a day, seven days a week. Nor is it scientifically acceptable merely to as sume that since a full 165-hour week is roughly four times a 40-hour week, then there would be logic in setting the full-time level at about one-fourth, or 50 micrograms per cubic meter of air. Full-time exposure compared with exposure and withdrawal from expo sure poses different problems in elim ination of lead. Tests with Human Subjects Kettering Laboratory at the Uni versity of Cincinnati is carrying on experiments with human subjects that involve nearly full-time exposure to atmospheres with known lead concen trations. The object is to determine what concentration of lead in the air a person breathes may start an up turn in' measurable lead in the per son's blood. From this work, spon sored in pan by the U.S. Public Health Service, it is hoped that a reasonable yardstick can be developed for setting ambient air standards for lead, where desired, as is being done for many other substances found in the air. The fact that there is no scientific basis now fpr setting any such figure is conceded by the state of California which has been studying the situation for some yean and has not as yet found any acceptable method for de termining a lead/air standard, al though standards have been set for a number of other substances emitted into the air from various sources. During 1967. however, two states did adopt a figure for lead in the ambient air. despite admitted lack of founda tion for these figures. The state of Pennsylvania set a "tentative" limit of five micrograms per cubic meter of air averaged over a 30-day period. Al though this figure was said to be derived from preliminary data devel oped by Dr. Robert Kehoe of Ketter ing Laboratory. Dr. Kehoe personally appeared before the Pennsylvania Department of Health hearings to dis pute the application of his data in this way and to testify that research in its present stage showed the figure to be too low. He added that any figure calculated on present data "is not necessarily or even probably cor rect." (23) The state of Montana later adopted this same standard, upon recommen dation of the U.S. Public Health Serv ice. even though the PHS spokesman gave no scientific reason for this figure and told the State Board of Health that: "Information of the effects ot lead in the atmosphere is indeed sparse ... As far as we are aware, there are no cases of clinical lead poison ing that can be attributed to expo sure to lead in (he ambient atmos phere. The levels present, we found in most places, are thought to be safe, although (here are some places where exposures are subject to con siderable question ... Allowing for wide variability among individual persons, and a wide variability of exposures, and injecting a modest (actor of safety, we feel that 5 rrncrograms per cubic meter of lead for monthly average ot exposure is probably safe." But nowhere did (his spokeman give any data or backing for this figure as against any other value, whether higher or lower. The human exposure studies which are continuing at Kettering Labora tory are expected to shed more sci entific light on this complex subject when the experiments are completed. The question of whether the relatively small amounts of lead taken in by the average adult from air would have an effect on those particularly susceptible to disease has been at least partially answered by the Three Cities Survey in its study of patients with diseases affecting liver, kidney, lung or bone. These patients showed no unusual blood lead accumulations. Study of TEL Workers Another question that has been raised concerns exposure of long duration to relatively low levels of lead, such as might occur in persons exposed to continued high levels of air pollution. An analysis of the health records ot persons occupationally exposed to lead for many years does not indicate a correlation between such exposure and any health problem. The results of one such thorough anal ysis was reported at the October 1966 meeting of the Industrial Hygiene Foundation. (24) This was the study of employees in the tetraethyl lead (TEL) production facilities of a ma jor producing company. The TEL VC0000265fi group was suitable for this analysis because in addition to their normal exposure to lead, they were subject to some further exposure on their jobs: also, health data existed for the work ers over their entire period of em ployment. The study covered 1,120 men: 348 currently working in the TEL area who had been there six months or more; 348 men who had not had occupa tional lead exposure and who served as controls: and 424 men who had for merly worked in the TEL area for at least six months or more in the past. The first two groups were matched according to race. age. and length of service with the company. Measure ment of lead in urine excretions for TEL workers was almost double that of controls, showing a significant dif ference in lead absorption between the exposed and unexposed groups. Company medical records of the workers were reviewed for informa tion on the following items: history of important chronic disease, height and weight, blood pressures, hemo globin determinations, white blood cell counts, and electrocardiographic abnormalities. For the mosr common chronic dis eases. the TEL workers and prior TEL workers both showed lower preva lence than that of the controls, the study found. The summary of the findings said that though TEL production workers had an average urinary lead excretion more than double that of the general population, "no adverse effect on health of this degree of lead exposure was detected." Research Wfl] Provide Answers The need for continuing research was a consensus of the Public Health Serv ice symposium on environmental lead contamination held in December 1965 in Washington. A panel report noted that no explicit evidence was pre sented that suggested present lead bur dens were associated with any major contribution to disease in the popula- tion. The report said the possibility could not be excluded that present lead intakes might, in undetected fash ion. be related to certain ailments. The panel recommended epidemiological and laboratory studies to find out more about possible effects of present or higher lead levels on man. Other recommendations included: More accurate definition of the effec tive absorption of lead by inhalation; development of techniques for better assessment of body burden of lead, and "the biological mobility of lead in its several biological compartments, and continued, intensified studies on the relative contribution to the bios phere of lead from geological and technological sources." With these recommendations, the lead industry is in accord. It also expects that the research that it is sponsoring both alone and in participation with other groups, or the work being done by other organizations, will help pro vide answers to the questions that have been raised. The lead industry for many years has supported scientific studies of all as pects of the use of lead. New and ex panded programs are continuing through the International Lead Zinc Research Organization. These include plans to participate in a major study similar to the Three Cities Survey pre viously described, but on an expanded basis. Other projects will utilize new techniques, such as isotopic ratios, for measuring sources of lead in the en vironment. and will open up new av enues for keeping up with information about man's use of lead, especially about lead in the atmosphere. References 1. Committee on Occupational Toxico logy of Council on Occupational Health. American Medical Associa tion. Comment. Archives of Environ mental Health. 12:273. February 1966. 2.* U.S. Public Health Service. Survey of Lead In the Atmosphere of Three Ur ban Communities. PHS Publication No. 999-AP-I2. January 1965. 3. World Health Organization. No in crease in Lead Contamination Found by WHO Investigation. Press release WHO 36. December 15. 1965. 4. Kehoe, Robert A. The Harben Lec tures. 1960--The Metabolism of Lead in Man In Health and Disease. Jour nal of the Royal Institute of Public Health and Hygiene. 1961. J. Kehoe, Robert A. Metabolism of Lead Under Abnormal Conditions. Archives of Environmental Health 8:235-243. February 1964. 6. U.S. Public Health Service. Air Pol lution Measurements of the National Air Sampling Network--Analyses of Suspended Particulates. 1963. Robert A. Taft Sanitary Engineering Center. Cincinnati. Ohio. 7. Morris*. F.V.. Bolze. Calvin and Goodwin. John T. Jr. Smog Chamber Studies of Unleaded versus Leaded Fuels. Industrial and Engineering Chemistry 50:673. April 1958. 6. U.S. Public Health Service. Sympos ium on Environmental Lead Con tamination (December 13-15. 1965). Public Health Service Publication No. 1440. March 1966. 9. U.S. Public Health Service. The Use of Tetraethyl Lead in Gasoline: Its Relation to Public Health. Public Health Bulletin No. 163. 1926. 1C. Final Report of (he Departmental Committee on Ethyl Petrol. His Majesty's Stationery Office. London. 1930. PNYC00002657 11. U.S. Public Health Service. Public Health Aspects of Increasing Ten* ethyl Lead Content in Motor Fact Public Health Service Publication No. 712. 1959. 21. Goldwater. Leonard J. and Hoover. A. Walter. An International Study of "Normal" Levels of Lead in Stood and Urine. Archives of Environ mental Health 15:60-63. July 1967. 12. Hirschler. D.A.. Gilbert. L.F., Lamb. F.W., and Niebylski. L. Particulate Lead Compounds in Automobile Ex haust Gas. Industrial Engineering Chemistry 49:1131-1142. I9S7. 22.`Haley, Thomas J. Chronic Lead In toxication from Environmental Con tamination: Myth or Fact? Archives of Environmental Health. Vol. 12, June 1966. 13.'Robinson. E. and Ludwig, F.L. Sire Distribution of Atmospheric Lead Aerosols. Stanford Research Institute, Menlo Park. Cal.. 36 pp.t April 1964. 23.*Kehcc, Robert A. Testimony at Hear ing of Pennsylvania Department of Health, Harrisburg, January 19, 1967. 14. Cannon. H.L. and Bowles. 3.M. Con tamination of Vegetation by Tenethyl Lead. Science 137:765-766. 1962. J5.'Robinson. E.. Ludwig, F.L.. De Vries. J.E.. and Hopkins. T.E. Var iations of Atmospheric Lead Con centration and Type With Particle Size. Stanford Research Institute. Menlo Park. Cal.. 80 pp.. November 1963. 24. Stopps, Gordon J.. Maxfieid, Mary E., McLaughlin. Martha, and Pell, Sidney. Lead Research: Current Med ical Developmeota. Presented at 31st annual meeting of Industrial Hygiene Foundation, Pittsburgh, Pa., October 18-19. 1966. 25. American Conference of Govern ment Industrial Hygienists. 1014 Broadway. Cincinnati. O. 45202. Threshold Limit Values for 1967. 16. Hatch. T.F. and Gross. P. Pulmonary Deposition and Retention of Inhaled Aerosols. Academic Press. New York, 1964. 17. Chotak. J.. Schafer. L.J.. and Ster ling, T.D. The Lead Content of the Atmosphere. Journal of the Air Pol lution Control Association 11(6): 281-288. June 1961. 15. Cholak. J. and Bambach. K. Menaureaent of Industrial Lead Expoaare by Analyses of Blood and Excreta of Workmen. Journal of Industrial Hy giene and Toxicology 25:47-54, 1943. 19.*Hofreuter. D.H.. Caieotu E.J.. Kee nan. R.G.. and Xintaras, C. The Public Health Significance of Atmos pheric Lead. Archives of Environ mental Health 3:568-574, 1961. 20. Report of the Swb* Leaded Gaaoffne Commiarioo to the Federal Conscfl on lb Activities During the Period 1947-1960. Mitteilungen aus dem Gebiete der Lcbensmitteluntersuchung und Hygiene (Bern) 52(3): 135244. 1961. Other References `Lead Industries Association, Inc., New York City. Facts About Lead and Industrial Hygiene. 1965. Task Group on Lung Dynamics for Committee II. Health Physics 12(2):173-208, 1966. Newsholme. A. The Story of Modern Preventive Medicine. The Williams and Wilkins Company, 1929. Air PoButioe. World Health Organi zation Monograph Series No. 46. Columbia University Press. New York. 1961. `Schroeder. H. A. and Balassa. J. J. Abnormal Tree* Metals in Mao: Lead. Journal of Chronic Disease* (St. Louis) 14(4);408-425. October 1961. Bagchi. K.N.. Ganguly, H.D., and Sudor, J.N. Lead la Food. Indian Journal of Medical Research 28:441450. 1940. Warren. H.V. and Delavault. R.E. Observations on the Biogeochemis. fry of Lead In Canad*. Transactions of the Royal Society of Canada 54:]| 20. I960. Warren. H.V. Trace Elements and Epidemiology. Journal of the College of General Practitioners 6:517-531. 1963. "Ziegfeld, R.L. Importance and Uses of Lead. Archive* of Environmental Health 8:202-212. February 1964. Darum. W.H. and HafTtv. J. Occur rence of Minor Elements in Water. U.S. Geological Survey. Circular 445. 1961. Kehoe. Robert A. Normal Metabol ism of Lead. Archives of Environ mental Health 8:232-235. February 1964. Nusbaum. R.E.. Bun. E.M. and Gilmour, T.C, Trace Metal Studies of Bone in Relationship to Air Pollu tant Exposure. Archive* of Environ mental Health 10:227-232, February 1965. Lane. R. Health Control in Inorganic Lead Industries. Archives of Environ mental Health 8:243-250. February 1964. `Calandra, J. C. Lead In the Envir onment Presented at 38th annual meeting of The Lead Industrie* As sociation. Inc., St. Louis. Mo.. March 31-Aprii 1. 1966. Patterson. C.C. Cootaashteted and Natural Lead Environments of Man. Archives of Environmental Health 11:344, September 1965. Kehoe. Robert A.. Thamann. Fred erick and Cholak. J. On the Normal Absorption and Excretion of Lead. L Lead Abeorpdoo and Excretion Is Primitive Life. Journal of Industrial Hygiene 15:257-272. 1933. `Available /rom The Lead Industries Association, Inc. P'"fC000<^658