Geology is important for your health
As surprising as it may seem, geology is important for human health. Rocks are the fundamental building blocks of the Earth’s surface, full of important minerals and chemical elements. Most elements are taken into the human body through air, food and water. Weathering processes break down rocks into soils, and crops and animals are raised on these soils. Drinking water travels through rocks and soils as part of the water cycle, and much of the dust and some of the gases contained in the atmosphere are of geological origin. Medical Geology addresses health problems caused or made worse by rocks, minerals or water and geological processes - such as volcanic eruptions, earthquakes and atmospheric dust.
“All substances are poisons...”
The relation between rocks, minerals and human health has been known for centuries. Ancient Chinese, Egyptian, Islamic, and Greek texts describe the many therapeutic benefits of various rocks and minerals, as well as the many health problems they may cause. Paracelsus (1493-1541) put the basic law of toxicology into words: “All substances are poisons; there is none which is not a poison. The right dose differentiates a poison and a remedy”. Thus, intake of too much of any given chemical element, and of too little, can have equally detrimental biological effects.
Examples
There are many documented examples of these effects:
The spatial correlation of iodine-deficient rocks and soil with areas
of endemic goitre is well known in central European regions,
mountainous and rain-shadow areas, which partly reflect the supply of
iodine from the marine source via the atmosphere. However, the
bioavailability of iodine in soil is equally important.
Although selenium is an essential trace element, its toxicity
(selenosis) is widely documented as a cause of ill health in horses and
cattle in Ireland, Israel, Australia, Russia, Venezuela, China, United
States and South Africa. Seleniferous soil in Ireland is developed on
certain black shale as parental material; this shale is also enriched
in other trace elements, such as molybdenum, copper, cobalt and
uranium. By contrast, selenium deficiency is implicated in endemic
heart disease (Keshan disease), and endemic bone ossification
(Kashin-Beck disease) in humans in China, and in white muscle disease
in animals worldwide.
Arsenic toxicity in groundwater has received serious attention in
France, Hungary, Argentina, China, India, Taiwan, Thailand, Nepal,
Vietnam, Mexico, parts of the USA and Bangladesh. Up to 150 million
people are estimated to be at risk from arsenic in drinking water in
the densely populated, and fertile alluvial deltas of Bangladesh and
West Bengal alone. Recognised health problems resulting from chronic
exposure to arsenic in drinking water include skin disorders, notably
pigmentation change (melanosis and keratosis) and in some cases
cancer. While 14,000 patients with clinical symptoms have been
identified in Bangladesh, the numbers suffering from arsenicosis may be
in excess of 200,000.
In England, high levels of molybdenum in soil, and thence in pastures
and fodder, caused molybdenum excess in grazing cattle. Due to the
excess of this element, these cattle acquired a deficiency in another
element, copper. Copper deficiency in these cattle exhibited as
stunted growth, late maturity and decreased production. Supplementing
the molybdenum rich pastures with copper corrected the problem.
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