Medicine and Myth to Modern: Thoughts on Connections Between

Geology and Human Health

Hippocrates (460-377 BC)

“Whoever wishes to investigate medicine properly should proceed thus…We must also consider the qualities of the waters, for they differ from one another in taste and weight, so also do they differ much in their quality”

So Hippocrates appreciated the significance of human health in context of the characteristics of the natural environment

Marco Polo (1254-1324)

Su-chau

During his travels to China, Marco Polo noted a curious affliction in imported European horses that grazed on vegetation in Su-chau; symptoms only showed up in imported horses and were absent among horses that were raised in the area.

Observations Made by Marco Polo in Su-chau

“Travellers passing this way do not venture to go among these mountains with any beast except those of the country, because a poisonous herb grows here, which makes beasts that feed on it lose their hoofs; but beasts born in the country recognize this herb and avoid it.”

Geological investigations made much later indicated high concentrations of selenium in the soil of the Su-chau regions. Certain varieties of plants (including grasses) concentrate selenium in their tissues without ill effect. But…herbivores cannot cope with very high concentrations of selenium

Common symptoms of selenium poisoning:Weakening of hoofs/nails and hair (plus others that we will look at later on in course). So Marco Polo’s observations (together with geological evidence) suggest selenium poisoning.

“Curative Properties” of Minerals

Egyptians are known to have used Copper salts, wine and frankincense were used to wounds.

For many centuries after the fall of the Roman Empire, the Arabic world was the centre of scientific and medical knowledge (700 - 1500 AD) . Arabic pharmacists became skilled in the formulation of medicines from plants and minerals.

In the Medieval and Renaissance periods, use of mineral materials for the treatment of ailments was widespread. But many of the “curative” properties of minerals were attributed to supernatural factors.

The purported curative properties of minerals are not completely unfounded

Some minerals do have antibacterial properties (e.g. Halite-regular table salt)

Other minerals provide important elements for normal functioning of the human body (hence the use of minerals for the manufacture of dietary supplements).

“Curative Properties” of Minerals

Other “curative properties”are a bit more dubious(even now !)

By mid- to late- 20th century, people started to recognize links between disease and environmental factors

Examples:

Incidence of widespread “common” ailments such as goiter

Concentration of trace metals in food

Occurrence of unusual diseases associated with uses of common geologic materials

Goiter

Goiter (Latin guttur for "throat”) is an enlargement of the thyroid gland. Although generally not uncomfortable, goiter may interfere with swallowing or breathing.

Before the early part of the 20th century, goiter was very common in the developed world, but was especially prevalent in areas distant from water bodies. Adolescent goiter was once considered normal ! It is still common in developing nations !

In North America, once very prevalent in Midwest and Northwest U.S. (most common cause of draft rejection in Michigan, during WW I)

The Great Lakes, Midwest, and Intermountain regions became known as the "goiter belt".

As early as 1833, Jean Baptiste Boussingnault recommended the use of iodized salt to cure goiter.

By the early 1900s, it became widely apparent that a common cause of goiter was iodine deficiency (without enough dietary iodine, the thyroid gland can't make and release enough iodine-containing hormones).

Food grown on iodine-depleted soils of interior of North America are very poor in iodine. But…seafood and crops grown in coastal areas generally to contain sufficient iodine for normal thyroid functioning.

Goiter became rare in the North America after iodized salt was introduced in the 1920s.

Yay ! I’m goiter-free !

Minamata Disease

In 1956, in Minamata City located on the Yatsushiro Sea coast in Kumamoto Prefecture, the first Minamata Disease patient was reported as a patient suffering from neurological symptoms of unknown cause.

In 1965, Minamata Disease patients were also reported in the Agano River basin in Niigata Prefecture.

Minamata Disease: Symptoms

The initial symptoms included:

• numbness of limbs & area around mouth• sensory disturbance• difficulty with everyday hand movements• lack of coordination• weakness • tremor• slowed and slurred speech• altered vision and hearing

These symptoms worsened and led to general paralysis, involuntary movements, difficulty in swallowing, convulsions, brain damage, and death.

In 1968, the Japanese government sorted out knowledge related to Minamata Disease and announced its opinion.

Minamata Disease was determined to be a poisoning disease of central nervous system caused by methylmercury compound produced as by-product in the process of manufacturing acetaldehyde near Minamata City and upstream of Agano River

Methylmercury compound was discharged with the factory effluent and polluted the environment, and then, through the food chain, accumulated in fish and shellfish. Consequently Minamata Disease occurred when the inhabitants ate high amount of these seafoods.

2,265 persons affected by Minamata Disease on the Yatsushiro Sea coast and 690 persons in the Agano River basin

The Aftermath of Minimata Outbreak

In addition to being used in industrial applications, mercury is also used in large quantities in gold mining (used to separate gold from crushed ore) and is readily washed from soils in deforested areas. Miners release about 250 tonnes of mercury into the Amazon region each year, most ending up in rivers- some forms of bacteria can convert inorganic mercury to the dangerous methylated formMinamata-type symptoms have recently been documented in fishing communities of the Amazon Basin where mining and deforestation has been severe.

Recent Minimata Outbreaks ?

Determination of nature and extent of this outbreak relies on a broad knowledge base with a focus on interactions between physical, chemical, and biological systems – geologists are trained to understand these interactions.

Relevance of geological principles to current health concerns

Bone diseases (with a recent focus on osteoporosis)

-related to body’s ability to maintain healthy bone growth (obviously, in order to understanding the dynamics of bone mineralization, one must understand the manner in which the minerals form)

-recent studies have demonstrated that substitution of calcium by other ions (e.g. magnesium, strontium) may be more significant to bone health than previously thought

Health concerns related to dust (with recent focus on asbestos)

-different forms of “asbestos” (each with different mineral properties) have been shown to pose very different health risks

-geomedical studies on asbestos and other particulate mineral substances are currently investigated

-better understanding of effects of minerals on human health will impact public policies on the management of particulate substances

Relevance of geological principles to current health concerns, cont’d

Asbestosis: scarring of lung tissue due to inhalation of asbestos fibres

Relevance of geological principles to current health concerns, cont’d

Outbreaks of respiratory disease (e.g. asthma)-recent cases have shown links between respiratory disease and certain soil fungi

-geomedical studies are currently being conducted to see how factors such as soil-forming processes, climate, and the geochemical characteristics and parental rock materials of soils influence the proliferation of certain soil fungi

Trace element poisoning (due to high concentrations of arsenic, fluoride, lead, and other trace elements

Relevance of geological principles to current health concerns, cont’d

e.g. Guizhou Province, China

Clay used as binder for coal briquettes-releases high concentrations of fluorine when burned, leading to fluorosis

Burning of low-grade coal (which has replaced now-scarce wood as fuel) releases high concentrations of arsenic (people ingest arsenic via chili peppers dried over unvented stoves

Reduction of effects of trace metal poisoning here will require knowledge of the distribution of trace elements within fuel and clay deposits and the development of inexpensive field tests that can be used to determine trace element metal toxicity.

So how do geologists fit into the health equation ?

Geologists, being interdisciplinary scientists, must have a good understanding many aspects of Earth’s materials – their composition, physical and chemical properties, distribution, and the manner in which they interact.

The geologist’s understanding of the complex interface and interaction of substances in the natural environment, in both time and space, is essential to “getting to the root” of medical issues that relate to processes inherent to the Earth System.

Awareness of “the big picture” enhances the utility of information gleaned from more specific biological, chemical and physical studies. Geology serves as the “glue” for all Earth-based science.

End of Lecture