Public
Health
Policy
Forum
Health and the Environment in the 1990s Richard Doll, DM, FRS Health, according to the World Health Organization (WHO), is defined as a state of complete physical, mental, and social well-being. This is a fine and inspiring concept and its pursuit guarantees health professionals unlimited opportunities for work in the future, but it is not of much practical use for specialists in public health medicine who need to compare the states of health in different communities and at different times and who consequently need to give them numerical values. I shall therefore use the term health in the limited sense of a state distinguished by the absence of disease or of physical or mental defect, that is, the absence of conditions that detract from functional capacity whose incidence can be measured objectively. And because morbidity and mortality are so closely related, I shall assess health largely in terms of mortality and years of expectation of life, for which objective evidence is available for long periods throughout most of the world. As to environment, I shall start with the simple definition of the Oford English Dictionary: namely, "the conditions under which any person lives." We can, however, limit the conditions to those whose effects people are individually unable to control, and so exclude such conditions as the availability of tobacco and, in high-income societies, of a high-fat diet, as people exposed to them can choose alternative diets and whether or not to smoke. By excluding these conditions I do not exclude the effects of malnutrition in low-income societies in which a healthy diet may be beyond people's means; in these circumstances, a nutritionally inadequate diet must be regarded as a condition of the society in which the people live. Even with these restricted definitions, the subject is still so vast that I can deal with much of it only in outline. I shall
therefore describe first and very briefly the trends in mortality in the United States, as representative of what the World Bank calls the market economy countries of the industrialized world,' and the comparative conditions in the non-market economy industrialized countries and the developing countries. I shall examine in each case the environmental factors that have contributed to the trends and to the differences between them. Second, I shall seek to justify my statement that the changes that occur in each part of the world affect conditions everywhere else. I shall conclude by suggesting some priorities for the selection of the environmental factors that we should now most energetically seek to control.
Health and the Environment in the United States Expectation ofLife The simplest measure of the state of health of a country is the expectation of life at birth of its citizens. The trend in expectation of life at birth in the United States since the beginning of the century is shown in Figure 1, separately for males and females. The data for the years before 1928 refer only to the limited number of registration states (10 plus the District of Columbia until 1911 and then 30 plus the District of Columbia until 1927), but the lack of sharp breaks in the trend suggests The author is with the Imperial Cancer Research Fund Cancer Studies Unit, Radcliffe In-
firmary, Oxford, England. Requests for reprints should be sent to Sir Richard Doll, DM, FRS, Imperial Cancer Research Fund Cancer Studies Unit, Radcliffe Infirmary, Oxford OX2 6HE, UK. This paper was submitted to the Journal February 20, 1992, and accepted March 24, 1992.
American Journal of Public Health 933
>65,;~ ~ blacks
Public Health Poliy Forum
85 80
75-
700 65
60_
55
0
50
"
F
f
_
males over non-White males (almost all of whom at that time were Black) has progressively diminished, but in 1988 the difference was still about 5 years or, if comfemaleas parison is made only with Blacks, for separate data are now published, whom _,,~~~~~~~~~~~~males about 7 years.
Factors Responsible for Trends These increases in the expectation of
life have been brought about primarily by a reduction of over 90% in the mortality
rate for infants and children younger than 5 years of age, which was 30% at the start < 45 of the century and is now only 2%. As a Q 40 result, the increase of 23 years in the exwx 3 pectation of life at birth corresponds to an increase of only 14 years for those who 30 _ survive to reach the age of 5. Reductions 0'( in mortality have, however, occurred at all 1900 1910 1920 1930 1940 1950 1960 1970 1980 1988 other ages, as is shown in Figure 3; even Year for those older than 80 years of age the reduction has been as much as a third. FiGURE 1-Trend in exptaon of life at birth In the Unied States, 1900 to 1985, for The reasons for the reduced mortalmales (-o*) and females (x-x). ity in the early decades of the century are well known and not open to serious question, except as regards the relative importance of the various factors responsible for 85 the reduction. These were essentially factors that diminished the risk or the fatality 80 infection, including improved nutrition, of 75 family size, better provision of wasmaller non-whIte 70 with feces, control of ter uncontaminated _ ~~~~~~~~~~~~~~~~~non-whitw @ the vectors of malaria, pasteurization of milk, matemal education in the care of infants, and immunization. Treatment of infection played little if any part in the reduction of mortality, as treatment was ineffective until the introduction generally 0 35-_ of the sulfa drugs in 1936. The principal roles in reduction of mortality must be attributed to the improved environment (deas the conditions underwhich people fined 0 ~ 490 9018 90 17 95 190 12-90 14 lived) brought about by the increased standard of living consequent on industrial de1900 1910 1920 1930 1940 1950 1960 1970 1980 1988 velopment and, secondarily, to the appliYear cation of knowledge of the causes of disease and the way disease could be preion of life at birth in the United States, 1900 to 1985, for FIGURE 2-Trend in ex With the advent of sulfa drugs and vented. Blacks and (@-*). Whites (C-0), non-Whites (x-x), the development of a series of antibiotics following the first use of a laboratory preparation of penicillin in 1941, therapy has In all industrialized countries the that the pre-1928 figures were reasonably played an increasingly important role in state of health varies between social representative of the whole country. In the control of infection and, more regroups, and this has been particularly easy both sexes increases have occurred cently, in the treatment of cancer and ischto see in the United States because of the emic heart disease. Other factors are betthroughout the period, apart from brief inpublication of vital statistics by race and ter anesthesia and postoperative care, tervals in the late 1920s, 1930s, and 1960s. the broad correlation between race and further immunization, and the discovery In total the increases have been large. The exin the differences The of the means to reduce substantially the status. social than females for increase has been greater nonand White age-specific risk of degenerative disease between life of pectation and proportionboth absolutely for males, by the avoidance of smoking and the reWhite males at different times in this cenately, and the female advantage of nearly duction of blood pressure and of blood 1900 The 2. tury are shown in Figure 3 years in 1900 to 1904 has more than doulow-density-lipoprotein cholesterol. White for 17 nearly of years advantage bled to nearly 7 years in the late 1980s. c 0
934 American Journal of Public Health
July 1992, Vol. 82, No. 7
Public Health Poliy Forum The longer expectation of life of females is a universal phenomenon in industrialized countries; it is partly genetic in origin and partly behavioral. The widening of the gap between the sexes that began immediately after the Second World War and continued into the 1970s, and its subsequent narrowing (Table 1), can be attributed largely to cigarette smoking being taken up first by men and only later by women. The different trends in mortality from the principal diseases related to smoking (heart disease, respiratory cancer, and chronic obstructive pulmonary disease) could account for most of the difference between the trends in the two sexes from 1950 to 1970 and for all of it from 1970 to 1988 (Table 2). The factors responsible for the shorter expectation of life of Black Americans than of Whites and for the partial closing of the gap up to 1960 are equally clear, though again difficult to put in hierarchical order. In this case, the direct medical effects of genetic factors operate in both directions, and essentially the whole difference must be attributed to differences in the social environment in which people live, operating sometimes indirectly by modifying behavior and sometimes directly via malnutrition, overcrowding, and a deficiency of medical care.2- The narrowing of the gap, which occurred between 1900 and 1960, can be attributed almost entirely to the differential reduction in mortality in infancy and childhood, as the difference in the expectation of life between Whites and Blacks in adult life has changed relatively little (Table 3). The narrowing of the gap, therefore, was due to the factors referred to previously that improved the health of infants and children in all sections of the community, principally by reducing the risk of infection.
Role of the Environment These factors have their origins partly in increased scientific knowledge, but at least as much, if not much more, in the changes in the environment that have accompanied the increased wealth produced by industrial and agricultural development, that is, the reduced prevalence of malnutrition and of imperfectly preserved food, the provision of ample water supplies uncontaminated with pathogenic organisms, the reduced prevalence of pathogenic parasites or their vectors, the better housing and smaller families, and the increased opportunities for education. There are, however, other aspects of industrial and agricultural development that
July 1992, Vol. 82, No. 7
750 10
Health
Policy
Forum
Health and the Environment in the 1990s Richard Doll, DM, FRS Health, according to the World Health Organization (WHO), is defined as a state of complete physical, mental, and social well-being. This is a fine and inspiring concept and its pursuit guarantees health professionals unlimited opportunities for work in the future, but it is not of much practical use for specialists in public health medicine who need to compare the states of health in different communities and at different times and who consequently need to give them numerical values. I shall therefore use the term health in the limited sense of a state distinguished by the absence of disease or of physical or mental defect, that is, the absence of conditions that detract from functional capacity whose incidence can be measured objectively. And because morbidity and mortality are so closely related, I shall assess health largely in terms of mortality and years of expectation of life, for which objective evidence is available for long periods throughout most of the world. As to environment, I shall start with the simple definition of the Oford English Dictionary: namely, "the conditions under which any person lives." We can, however, limit the conditions to those whose effects people are individually unable to control, and so exclude such conditions as the availability of tobacco and, in high-income societies, of a high-fat diet, as people exposed to them can choose alternative diets and whether or not to smoke. By excluding these conditions I do not exclude the effects of malnutrition in low-income societies in which a healthy diet may be beyond people's means; in these circumstances, a nutritionally inadequate diet must be regarded as a condition of the society in which the people live. Even with these restricted definitions, the subject is still so vast that I can deal with much of it only in outline. I shall
therefore describe first and very briefly the trends in mortality in the United States, as representative of what the World Bank calls the market economy countries of the industrialized world,' and the comparative conditions in the non-market economy industrialized countries and the developing countries. I shall examine in each case the environmental factors that have contributed to the trends and to the differences between them. Second, I shall seek to justify my statement that the changes that occur in each part of the world affect conditions everywhere else. I shall conclude by suggesting some priorities for the selection of the environmental factors that we should now most energetically seek to control.
Health and the Environment in the United States Expectation ofLife The simplest measure of the state of health of a country is the expectation of life at birth of its citizens. The trend in expectation of life at birth in the United States since the beginning of the century is shown in Figure 1, separately for males and females. The data for the years before 1928 refer only to the limited number of registration states (10 plus the District of Columbia until 1911 and then 30 plus the District of Columbia until 1927), but the lack of sharp breaks in the trend suggests The author is with the Imperial Cancer Research Fund Cancer Studies Unit, Radcliffe In-
firmary, Oxford, England. Requests for reprints should be sent to Sir Richard Doll, DM, FRS, Imperial Cancer Research Fund Cancer Studies Unit, Radcliffe Infirmary, Oxford OX2 6HE, UK. This paper was submitted to the Journal February 20, 1992, and accepted March 24, 1992.
American Journal of Public Health 933
>65,;~ ~ blacks
Public Health Poliy Forum
85 80
75-
700 65
60_
55
0
50
"
F
f
_
males over non-White males (almost all of whom at that time were Black) has progressively diminished, but in 1988 the difference was still about 5 years or, if comfemaleas parison is made only with Blacks, for separate data are now published, whom _,,~~~~~~~~~~~~males about 7 years.
Factors Responsible for Trends These increases in the expectation of
life have been brought about primarily by a reduction of over 90% in the mortality
rate for infants and children younger than 5 years of age, which was 30% at the start < 45 of the century and is now only 2%. As a Q 40 result, the increase of 23 years in the exwx 3 pectation of life at birth corresponds to an increase of only 14 years for those who 30 _ survive to reach the age of 5. Reductions 0'( in mortality have, however, occurred at all 1900 1910 1920 1930 1940 1950 1960 1970 1980 1988 other ages, as is shown in Figure 3; even Year for those older than 80 years of age the reduction has been as much as a third. FiGURE 1-Trend in exptaon of life at birth In the Unied States, 1900 to 1985, for The reasons for the reduced mortalmales (-o*) and females (x-x). ity in the early decades of the century are well known and not open to serious question, except as regards the relative importance of the various factors responsible for 85 the reduction. These were essentially factors that diminished the risk or the fatality 80 infection, including improved nutrition, of 75 family size, better provision of wasmaller non-whIte 70 with feces, control of ter uncontaminated _ ~~~~~~~~~~~~~~~~~non-whitw @ the vectors of malaria, pasteurization of milk, matemal education in the care of infants, and immunization. Treatment of infection played little if any part in the reduction of mortality, as treatment was ineffective until the introduction generally 0 35-_ of the sulfa drugs in 1936. The principal roles in reduction of mortality must be attributed to the improved environment (deas the conditions underwhich people fined 0 ~ 490 9018 90 17 95 190 12-90 14 lived) brought about by the increased standard of living consequent on industrial de1900 1910 1920 1930 1940 1950 1960 1970 1980 1988 velopment and, secondarily, to the appliYear cation of knowledge of the causes of disease and the way disease could be preion of life at birth in the United States, 1900 to 1985, for FIGURE 2-Trend in ex With the advent of sulfa drugs and vented. Blacks and (@-*). Whites (C-0), non-Whites (x-x), the development of a series of antibiotics following the first use of a laboratory preparation of penicillin in 1941, therapy has In all industrialized countries the that the pre-1928 figures were reasonably played an increasingly important role in state of health varies between social representative of the whole country. In the control of infection and, more regroups, and this has been particularly easy both sexes increases have occurred cently, in the treatment of cancer and ischto see in the United States because of the emic heart disease. Other factors are betthroughout the period, apart from brief inpublication of vital statistics by race and ter anesthesia and postoperative care, tervals in the late 1920s, 1930s, and 1960s. the broad correlation between race and further immunization, and the discovery In total the increases have been large. The exin the differences The of the means to reduce substantially the status. social than females for increase has been greater nonand White age-specific risk of degenerative disease between life of pectation and proportionboth absolutely for males, by the avoidance of smoking and the reWhite males at different times in this cenately, and the female advantage of nearly duction of blood pressure and of blood 1900 The 2. tury are shown in Figure 3 years in 1900 to 1904 has more than doulow-density-lipoprotein cholesterol. White for 17 nearly of years advantage bled to nearly 7 years in the late 1980s. c 0
934 American Journal of Public Health
July 1992, Vol. 82, No. 7
Public Health Poliy Forum The longer expectation of life of females is a universal phenomenon in industrialized countries; it is partly genetic in origin and partly behavioral. The widening of the gap between the sexes that began immediately after the Second World War and continued into the 1970s, and its subsequent narrowing (Table 1), can be attributed largely to cigarette smoking being taken up first by men and only later by women. The different trends in mortality from the principal diseases related to smoking (heart disease, respiratory cancer, and chronic obstructive pulmonary disease) could account for most of the difference between the trends in the two sexes from 1950 to 1970 and for all of it from 1970 to 1988 (Table 2). The factors responsible for the shorter expectation of life of Black Americans than of Whites and for the partial closing of the gap up to 1960 are equally clear, though again difficult to put in hierarchical order. In this case, the direct medical effects of genetic factors operate in both directions, and essentially the whole difference must be attributed to differences in the social environment in which people live, operating sometimes indirectly by modifying behavior and sometimes directly via malnutrition, overcrowding, and a deficiency of medical care.2- The narrowing of the gap, which occurred between 1900 and 1960, can be attributed almost entirely to the differential reduction in mortality in infancy and childhood, as the difference in the expectation of life between Whites and Blacks in adult life has changed relatively little (Table 3). The narrowing of the gap, therefore, was due to the factors referred to previously that improved the health of infants and children in all sections of the community, principally by reducing the risk of infection.
Role of the Environment These factors have their origins partly in increased scientific knowledge, but at least as much, if not much more, in the changes in the environment that have accompanied the increased wealth produced by industrial and agricultural development, that is, the reduced prevalence of malnutrition and of imperfectly preserved food, the provision of ample water supplies uncontaminated with pathogenic organisms, the reduced prevalence of pathogenic parasites or their vectors, the better housing and smaller families, and the increased opportunities for education. There are, however, other aspects of industrial and agricultural development that
July 1992, Vol. 82, No. 7
750 10
