Medical geology

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Introduction
01 Cancer
02 Ozone
03 Urban air
04 Air pollutants
05 Blue-green algae
06 Water mutagens
07 Contamination
08 Chernobyl
09 Radon
10 Medical geology
11 Renal hazards
12 Organohalogens
13 Estrogens
14 Food hazards
15 Mycotoxins
16 Poisoning
17 Genetics
18 Risk

Ordering

(Excerpt from Chapter 10)

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Mother nature is a polluter

In June 1991 the volcano Pinatubo had an eruption. Over just two days the volcano ejected about 10 billion tons of magma and 20 million tons of sulfur dioxide, and the resulting aerosols influenced the global climate for at least three years. This event alone introduced 2 million tons of zinc, 1 million tons of copper and 5,500 tons of cadmium into the surface environment. The millions of tons of ash pumped into the atmosphere spread over thousands of square kilometres, probably containing all the elements in the Periodic System. In addition to the elements known to be essential to life, such as hydrogen, carbon, nitrogen, oxygen, sodium, potassium, calcium, magnesium, iron, copper, zinc, phosphorus, sulfur and iodine, volcanoes also redistribute those elements which under certain conditions are regarded as harmful, such as arsenic, beryllium, cadmium, mercury, lead, radon and uranium plus the remaining elements, some of which have still undetermined biological effects. Similar volcanic events have occurred every few years throughout geological history. From the standpoint of natural releases of metals to the environment, it is important to realize that there are on an average 60 volcanoes erupting on the surface of the earth at any given time. The total flux of metals from these eruptions is significant. Submarine volcanism is even more significant than that at continental margins. It has been conservatively estimated that there are at least 3,000 vent fields on the mid-ocean ridges.

The planet earth is thus the ultimate source of all metals. Metals are ubiquitous in the lithosphere, where they are inhomogenously distributed and occur in different chemical forms. Ore deposits are merely natural concentrations which are commercially exploitable. While such anomalous accumulations are the focus of mineral exploration the background concentrations of metals which occur in common rocks, sediments and soils are of greater significance to the total metal loading in the environment. Indeed, all known elements are present at some level of concentration throughout the natural environment. They are present in minerals, vegetables and animals, and their beneficial and harmful effects have been present since evolution began.

An understanding of the nature and magnitude of these geological sources is a prerequisite for developing approaches in assessing the risk posed by metals in the environment. It is important to be able to distinguish between natural and anthropogenic contributions to metal loadings. In addition, a knowledge of natural processes is fundamental in understanding the fate of those metals which are released as a result of human activity. Keep in mind that Mother Nature is indeed a polluter.

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Olle Selinus is a Ph.D. in geology and worked during the 1960s and 1970s on mineral exploration with a mining company and at the Geological Survey of Sweden. Beginning in the 1980s he has carried out work and research mainly in environmental geochemistry and geostatistical methods, including medical geology. He is the organizer of several international conferences in this field and an editor of publications, and has published some 40 papers. He is presently at the Geological Survey of Sweden working on research and international affairs. Olle Selinus is also an officer of the international environmental geology commission COGEOENVIRONMENT and the chairman of its international working group on Medical Geology.

Adrian Frank is a Ph.D. and a professor of toxicological chemistry. He has been working in the fields of forensic chemistry and occupational hygiene. Adrian Frank has worked since 1965 at the Dept of Chemistry, National Veterinary Institute, Uppsala, Sweden, on pesticide chemistry, nutritional and toxicological chemistry of trace elements in domestic and wild animals, taking a special interest in trace metals in the Swedish moose (Alces alces L.). He has devoted special interest to trace-element chemistry of the moose in the 1970s and became involved in the mysterious disease of the Swedish moose in 1988. He has published more than 100 papers in these fields. He is a member of the Centre for Metal Biology in Uppsala and member of the editorial board of the Science of the Total Environment. Emeritus since 1992.