Some of the relationships between geochemical environment and health and disease are well documented; for example, deficiency of iodine in soil and water and dysfunction of the thyroid gland—goiter and hypothyroidism in the adult, cretinism in the infant-child, and increased risk of thyroid cancer. Recent evidence suggests that those relationships we know about are but the tip of the iceberg, and that geochemical environment has a profound influence on the level of health of human beings and other animals; moreover, the geochemical environment, particularly as it affects intake and utilization of trace elements, plays a major causal role in many specific diseases. There is urgent need for a multidisciplinary approach to the important problem of identifying and characterizing relationships between geochemical environment and health and disease, because this problem is so complex that it cannot be resolved by geochemists, agronomists, toxicologists, nutritionists, epidemiologists, or pathologists working alone. Because I am a pathologist—and one particularly interested in geographic pathology—my approach to this problem is by examining the geographic patterns of disease with respect to the geochemical environment in which they occur, at the same time looking at the cause(s) and mechanism of development (pathogenesis) of those diseases in which there is reason to suspect that geochemical environment may play a causal role. With this approach, disease patterns must be considered not. merely in terms of incidence or prevalence of the disease, but also in terms of variations in its character: whether it is acute or chronic, mild or . . .

Preliminary surveys based on lake and stream sediments have been carried out in southern Ontario as a possible basis for geoepidemiological research. The survey of cores of lake sediments involved 40 cores taken from 20 lakes in southern Ontario. Each core was examined for copper, lead, zinc, cadmium, and nickel soluble in acid as well as for fossil pollen that was used to date the sample material. There was a direct relationship between the age of the core material, the location from which the cores were collected, and the trace-element content of the samples. The stream-sediment survey involved the collection of 1,105 samples of material from a 1,165 km 2 area around St. Catharines, Ontario. In this study, eight elements were determined in the samples, and it was concluded that variations in the distribution patterns for lead, strontium, and zinc were caused by man’s activities in some cases and by natural causes in others. It is concluded that surveys of lake or stream sediments may be important starting points for the collection of geochemical data.

Recent studies have presented the relationship of various geological, ground-water chemistry, and other environmental factors to death rates for cardiovascular-renal (CVR) and other chronic diseases in the same geographic areas. Several studies report a negative correlation of hardness in the drinking water with CVR diseases death rates. Other studies do not support the hypothesis of a protective role for hard water. In view of the complexity of the environment, other variables in the physical environment, as well as cultural and socioeconomic factors, also require careful consideration. In Indiana, a variation in CVR diseases death rates follows the Wisconsinan glacial boundary and areas of Wisconsinan outwash, with higher rates north of the boundary. Between these areas, there is a significant difference in soil pH, soil organic carbon, hardness, and possible sulfate in municipal water supplies. For the 92 counties of Indiana, CVR death rates for white males, ages 35 to 74 (age-adjusted), for 1959–1961 show a significant correlation with soil parameters pH and organic carbon, hardness of the drinking water, population density, occupation, income, dust in the air, and other variables. Multiple correlation of eight variables with CVR diseases death rates produces a value of 0.49. Additional measures of the death rate for varying time periods confirm the general conclusions. Although this moderately homogeneous group of counties presents problems in analysis, the study suggests that many variables often not taken into account may exert considerable influence. An appreciation of the complexity of environmental factors is needed in order to proceed with appropriate caution in the study of the extent and nature of the relationship of geological variables to chronic diseases rates.

Premature death among humans in the state of Missouri appears to have little relation to the composition of soils in the vicinity of their usual residency. Our conclusion contrasts with a considerable part of the literature, which implies that soil is a factor affecting human health. The difference may arise either because people living in a given environment may not expose themselves in such a way as to be affected by the soil or because other important factors may overshadow the effect of soils. Other studies have suggested a correlation between the incidence of either human disease or human mortality and soil characteristics. Most correlations have been of the simple bivariate type. The opportunity for a multivariate study has arisen only with the availability of chemical data on soils and mortality rates of humans from a common area. The distribution of elements in Missouri soils exhibits some regional pattern, but mortality distribution patterns are not regionally distinct. Therefore, stepwise multiple regression is used to define possible subtle relationships. This multivariate search tool identifies which of the 32 elements measured in 1,140 soil samples collected throughout Missouri best relate to human mortality risk. Differences in age, sex, and race are closely associated with mortality risk; adjustments for these factors have been made by direct methods. There is a possibility that other factors, presently not recognized, need to be measured and controlled before dismissing the idea of a soil influence on mortality. We are continuing the search for such factors.

An interdisciplinary group of faculty from the University of Colorado and from Colorado State University is studying molybdenum in the environment. Molybdenum plays an essential role in the nitrogen cycle of plants and may cause disturbance of copper metabolism in animals. The world's largest molybdenum-producing mine is at Climax, Colorado. Rivers in Colorado exhibit some of the highest reported concentrations of molybdenum in the United States. Colorado offers a model system for the study of the release and effect of molybdenum. The geochemistry of molybdenum is complex. The principal dissolved form of the metal in natural waters is an anion, MoO 4 − − . At values of pH below about 6, the bimolybdate ion, HMoO 4 − , becomes dominant. The bimolybdate ion is relatively immobile in natural systems at low pH, probably because of adsorption or coprecipitation on metal hydroxides. In the acid soils of the alpine environment of Colorado, molybdenum forms a well-defined halo of elevated concentrations around a mineralized, undisturbed zone in the bedrock. We have attempted to define a natural datum or background level of molybdenum in the vicinity of the undisturbed mineralized zone and to compare the concentrations of molybdenum in the undisturbed area to those present in the vicinity of mines and mills in the same mountainous area. Such a comparison is extremely difficult and tenuous because of differences in drainage and glaciation between the two areas.

INTRODUCTION Cadmium and zinc are chemically similar (Cotzias and others, 1961; Cotton and Wilkinson, 1966). They therefore compete with one another for a variety of ligands (Pulido and others, 1966a; Gunn and others, 1968). Because cadmium is considered to have only adverse effects in biological systems (Friberg and others, 1971) and zinc is an essential nutrient (Sandstead, 1973), the significance of their competitive interactions for health merits investigation. In this paper we will examine the hypothesis that competition between zinc and cadmium for biological ligands has important implications for health. ZINC AND CADMIUM IN THE ENVIRONMENT Cadmium is a relatively rare element. Its average concentration in the Earth’s crust is about 0.5 ppm (Heindl, 1970). In nature it is closely associated with zinc (Friberg and others, 1971). The zinc:cadmium ratio of most minerals and soils ranges from 100:1 to 12,000:1 (Bowen, 1966; Schroeder and others, 1967). In the United States, cadmium is obtained commercially only as a by-product during the processing of zinc-bearing ores (Heindl, 1970). Its production has risen steadily during the past three decades (Moulds, 1969). This growth can be described by the equation y = 0.21 x – 1.81, where y represents the annual production in millions of pounds and x is the year minus 1900. Sixty percent (8 million pounds in 1968) of the cadmium produced each year is used for electroplating (Heindl, 1970), and products plated with cadmium are widely used throughout the United States (Flick and others, 1971). Such cadmium-plated products and cadmium-containing materials may be . . .

Many people are saying, this is the age of Aquarius. Many people are also saying this is the age in which we must express our concern for the biosphere or perish. Biosphere has such far-reaching connotations, however, that it is beyond the comprehension of most of us, including the great majority of those who have recently discovered it, and who so vigorously assert their willingness for deep personal involvement in efforts to save it. With respect to human health and disease, I have found it useful to think of ecology at three levels of operation: (1) As it involves the biosphere. Admittedly there is an essential interrelationship among all things: everything has an effect on everything else. Unfortunately, I do not know how to formulate, much less solve, the infinite number of equations that would be required to handle this infinite number of variables. (2) As it involves macroecology, which I relate to man. In the sense that I am using it, macroecology includes those factors that have a demonstrably significant effect on man’s external environment. The distinction between biosphere and macroecology (of man) is a device of communication that makes it convenient to select from the former those factors that have a more direct effect upon man and, thus, deserve priority in our concern. (3) As it involves microecology, which, as I am using the term, concentrates on those factors that affect man’s internal environment.