13. The Geologic Aspects of Environmental Health

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13. The Geologic Aspects of Environmental Health

• Lecture outline
• Introduction to Environmental Health
• Some Geologic Factors of Environmental Health
• Trace Elements in Health
• Chronic Disease and Geologic Environment
• Radioactivity and Radon Gas
• Risk Assessment in Toxicology
• Case Study Arsenic in Ganges

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Introduction to Environmental Health

• Geologic dimensions of the complex relationship
  between disease and environment
• Trace elements vary in abundance between soils,
  surficial deposits, bedrock
• Micronutrients
• Toxic
• Radioactivity in rocks, gases (e.g., radon)
• Water carries contaminants derived from geologic
  processes
• Dissolved
• Particulate

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Some Geologic Factors of Environmental Health

• Living tissue is composed primarily of 11
  (bulk) elements O, C, H, N, Ca, P, S, K, Na,
  Cl, Mg
• Living tissue also requires minute levels of
  several other (trace) elements Fl, Cr, Mn, Co,
  Cu, Zn, Se, Mo, I
• Other (age) elements accumulate in tissue with
  age Ni, As, Al, Ba, Pb
• Some elements not known to be essential to human
  life Ti

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Some Geologic Factors of Environmental Health

• Important to understand biogeochemical processes
  of rock cycle weathering, cementation
• Mud and mud-derived rocks (e.g., shales,
  mudstones, slates, schist)
• Adequate amounts of most micronutrients (and
  non-essential elements)
• Cations and anions are readily adsorbed on clays
  and organics
• Some black (organic-rich) shale well known for
  unusually high abundances of U, Zn, Se, others

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Some Geologic Factors of Environmental Health

• Granites and rhyolites may be strongly enriched
  in Mo, Sn, Be, rb
• Granite pegmatites high in Be, B, Li
• Clean, quartz sandstones low in trace elements
• contain some (Zr, Ti, B) but locked-up in
  insoluble minerals zircon, rutile, tourmaline
• Not available to soil microflora, microfauna,
  plants

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Some Geologic Factors of Environmental Health

• Intermediate silica-content igneous rocks
  (andesite, diorite) good balance of trace
  elements
• Mafic basalts and gabbros
• Elevated content of Co, Ni, Se, Cr
• Depleted in Zn, Mo
• Soils derived from olivine/Mg-silicate bedrock
  (dunite, serpentine
• Severe deficiencies in Ca, K, essential
  micronutrients
• May contain near-toxic levels of Cr

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Some Geologic Factors of Environmental Health

• Bioavailability
• If not tightly bound in insoluble mineral grains
  controlled by soil moisture pH
• When soil moisture is acid most metal cations
  have enhanced mobility (immobile in alkaline
  soils)
• Se Mo more soluble in alkaline soils and water
• Mercury subject to biomagnification
• 60,000 children born each year in USA with
  elevated concentrations of Hg (NAS)
• 41 states have issued advisories on eating fish
  from Hg-contaminated waters

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Trace Elements in Health

• Dose-response curve
• Optimum concentrations
• Two thresholds at which harmful conditions begin

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Trace Elements in Health

• Toxic dose-response curve
• TD-50 concentration at which 50 of population
  experiences a particular symptom (e.g., disease,
  death)

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Trace Elements in Health

• Imbalance of fluorine
• Calcium fluoride helps prevent tooth decay helps
  form large-resistant crystals of apatite (calcium
  phosphate) in teeth and bones
• Can reduce osteoporosis
• Fairly abundant in rocks esp. volcanic ash

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Trace Elements in Health

• Imbalance of iodine
• Thyroid gland (at base of neck) requires iodine
  to function
• Lack of iodine causes goiter tumor causing
  enlargement of thyroid gland
• Can cause stunted growth and mental disability in
  children born to mothers with iodine deficiency
• Treat deficiency with iodize salt

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Trace Elements in Health

• Imbalance of zinc
• Zinc is essential for plant (crop) growth
  affects yields, seed development
• Low in areas with strongly leached soils Coastal
  Plain of NC, GA, FL
• Also low in states with aeolian sand cover Zn
  not transported as readily as quartz sand
• Zn deficiencies in human lung cancer, arterial
  disease

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Trace Elements in Health

• Imbalance of lead
• Each year 12,000-16,000 American children under
  age 9 are treated for acute lead poisoning
• about 200 die
• 30 of survivors suffer from palsy, partial
  paralysis, blindness, mental impairment
• Can cause damage to unborn fetuses
• High in shales, Boone Fm (Mississippian-age
  limestone) ore replaces limestone in zones
  sphalerite (ZnS) and galena (PbS) are commercial
  minerals

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Trace Elements in Health

• Lead declines

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Trace Elements in Health

• Imbalance of selenium
• Found in elemental form in metallic or
  crystalline form odorless and tasteless
• In gaseous form smells like garlic (one form is
  very toxic hydrogen selenide)
• Use in insecticides and in paint for ships
  (prevents growth of barnacles)
• Photoelectric properties make it useful in light
  meters, electronic eyes
• Steel industry uses Se for strength, corrosion
  resistance
• Used as rubber vulcanizer, dandruff control
  shampoo, to color glass red or pink

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Trace Elements in Health

• Imbalance of selenium
• Beneficial to animals at 0.04 to 0.1
• More problems from deficiency than from excess
• Toxic gt 4 ppm
• negative reputation from animal affliction known
  as blind staggers muscular dystrophy)
• 1907-08 15,000 sheep died north of Medicine Bow
  (assumed to be caused by plants with seleniferous
  vegetation (but no pathology report to confirm
• Use for humans to reduce toxic effects of excess
  Cd, As
• May be useful as antioxidant and anticancer agent
• Se poisoning rare in humans drinking water
  standard is 10 ppm

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Trace Elements in Health

• Imbalance of selenium
• Found in volcanic tuff, coal deposits, marine
  shales
• Not readily available if soils are acidic (e.g.,
  Hawaii)
• In alkaline conditions subject to
  biomagnification by selenium concentrating plants
  (e.g., woody aster, milk vetch) has been found
  up to 15,000 ppm
• Seleniferous soils derived from Cretaceous-age
  marine shales bound with clay and iron oxides
• In WY Cody Shale, Steele Shale, Niobrara Fm.,
  Browns Park Fm.
• Because Se accumulates in organic material found
  in fossil fuels (e.g., coal)

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Trace Elements in Health

• Imbalance of selenium
• Similar to S
• Se S can replace each other in compounds
• Same symptoms can be produced by S and Se
• Oxidized groundwater dissolves U, Se, As
  deposited with change to reducing conditions
  roll-front deposits
• When oxidized Se adsorbed on clays, iron oxides,
  organic particles can find Se enriched fluvial
  and lake deposits

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Chronic Disease and Geologic Environment

• Heart disease and the geochemical environment
• Related to chemistry (esp. hardness) of drinking
  water
• Hardness function of Ca Mg (if low water is
  soft)
• Communities with soft water have higher rates of
  heart disease (e.g., stroke blockage/rupture of
  blood vessel in brain)
• Possible mechanisms (cause-and-effect not
  confirmed)
• Soft water is acidic ? corrode pipes ? release
  trace elements
• Some substances dissolved in hard water may help
  prevent heart disease

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Chronic Disease and Geologic Environment

• Japan stroke related to sulfate bicarbonate
• In sulfur-rich volcanic rocks in NE Japan low
  Ca, Mg, bicarbonate but high sulfate
• In sedimentary rocks high Ca, Mg, bicarbonate
  (hard water)

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Chronic Disease and Geologic Environment

• Ohio
• Sulfate-rich drinking water from coal-bearing
  rocks in SE Ohio
• Low sulfate/high bicarbonate in waters drainage
  glacial deposits

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Chronic Disease and Geologic Environment

• Georgia
• High death rates from cardiovascular disease
  high Zr in strongly-leached clays sands
• Low death rates abundant trace elements known to
  protect from CVDMn, Cr, V, Cu

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Radioactivity and Radon Gas

• Nature of radioactivity
• Elements substances that cannot be changed into
  other substances by ordinary chemical means
• Atoms have nucleus of protons neutrons
  surrounded by orbiting electrons
• Entire weight is in nucleus so atomic mass
  protons neutrons
• Atomic number protons (unique for each
  element)
• Atom smallest part of an element that can exist
  alone or in combination with other elements

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Radioactivity and Radon Gas

• Nature of radioactivity
• Atoms can gain or lose electrons form ions ( or
  charge)
• Isotopes forms of an element with different
  atomic mass (238U vs. 235U both have atomic
  number 92)
• Radioactive isotope (radioisotope) undergoes
  spontaneous nuclear change while emitting one or
  more forms of radiation
• Alpha particles 2 protons 2 neutrons (massive,
  slow, low penetration of solids)
• Beta particles energetic electrons
• Gamma radiation highest energy, travel far
  fast, deep penetration of solids)

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Radioactivity and Radon Gas

• The health danger from radioactive radiation
• Depends on kind of radiation, where exposure
  occurs, half-life of isotope, physical/chemical
  state
• Radon-222 low energy, short half-life, dangerous
  because it is a gas
• Alpha radiation dangerous only when
  alpha-emitting isotope is inhaled or ingested
  stopped by body tissue w/I short distance
• Gamma rays dangerous inside or outside of body
  (need shielding for protection)

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Radioactivity and Radon Gas

• The health danger from radioactive radiation
• Dose of 5000 millisieverts lethal to all exposed
  people
• Dose from 1000-2000 mSv causes vomiting, fatigue,
  miscarriages
• Maximum allowable dose for workers 50 mSv ( 30x
  avg. background radiation from all sources)
• Maximum permissible for general public 5 mSv (
  3x avg. background radiation)

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Radioactivity and Radon Gas

• Background radiation
• depends on elevation and bedrock
• High gamma radiation in mountain states vs. low
  at sea level
• Granite rocks contain more radioactive minerals
  vs. low in limestone
• From rocks/soil avg. 0.35 millisieverts/person/ye
  ar

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Radioactivity and Radon Gas

• Radon gas
• Naturally occurring radioactive gas colorless,
  tasteless, odorless
• Radioactive decay of U-238 produces Ra which
  decays to Ra-222-226
• Look for U-bearing rocks
• Elevated concentrations known to cause lung
  cancer up to 30,000 deaths/year in USA

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Radioactivity and Radon Gas

• Radon gas
• Radon activity in different environmental settings

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Radioactivity and Radon Gas
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Radioactivity and Radon Gas

• Geology of radon gas
• High in some dark shales some granites
• Reading Prong area in PA-NJ-NY famous for high
  radon gas
• Geologic faults commonly enriched w/ U
• Movement of radon gas attenuated by high soil
  moisture
• Radon Hot Springs, NM

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Radioactivity and Radon Gas

• Hazard from radon gas
• Enters homes through
• Cracks/seeps in walls, basements
• Groundwater pumped into homes
• Construction materials made of substances that
  emit radon gas
• Est. 1 in 7 homes in USA may have elevated levels
  of radon gas

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Risk Assessment in Toxicology

• Steps to take in risk assessment
• Hazard identification will exposure cause health
  problems?
• Dose-response assessment
• Exposure assessment duration, frequency,
  intensity of exposure
• Risk characterization compare risk of exposure
  (from 3 steps above) to legal, social, political,
  economic, technical issues involved in mitigation

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Case Study Arsenic Contamination in the
Groundwater of West Bengal, India, and Bangladesh

• India
• Pop 1 Billion
• Area 3,287,590 km2
• Life Expectancy 62.5 yrs
• Bangladesh
• Pop 123 Million
• Area 147,570 km2
• Life Expectancy 58 yrs

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Why Study Arsenic Contamination?
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Why Study Arsenic Contamination?
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Why Study Arsenic Contamination?
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Effects of Arsenic Contamination

• Melanosis
• Leucomelanosis
• Keratosis
• Hyperkeratosis
• Dorsum
• Nonpetting Oedema
• Gangrene
• Can lead to internal cancers

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Background

• Surface water in India and Bangladesh contains
  bacterial contamination not sanitary

• Water wells were drilled to provide fresh
  drinking water as early as 1960

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The Problem

• West Bengal, India
• Wells drilled into pyrite-coated alluvial
  sediments of the Ganges River Alluvium and Delta
  deposits for municipal and agricultural use
• Skin lesions and other diseases began to appear
• As a result, the School of Environmental Studies
  (SOES), Jadavpur University, India conducted
  research in the West Bengal district

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The Problem
West Bengal, India

• 20,000 water wells were analyzed
• 45 of the wells reported As levels above .05
  mg/l
• Avg. As concentration of the wells .20 mg/l

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The Problem
West Bengal, India

• 34 million within contaminated districts
• Up to 20 of population could show signs of As
  contamination

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The Problem

• While studying As contamination in West Bengal,
  India, the SOES discovered As contamination in
  neighboring Bangladesh
• Contaminated sediment was found to be
  Plio-Pleistocene age that also extended into
  Bangladesh

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The Problem

• Bangladesh
• 34 out of 64 districts have plio-Pleistocene
  sediments
• 27 of the 34 districts tested () for As
  contamination

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The AnswerWhat caused the As contamination?

• During Plio-Pleistocene times, sediment was
  deposited in the Ganges River delta that
  contained arsenic in the form of mineral deposits
  (As-rich Fe oxyhydroxide)
• Two Possible Theories
• Drawdown causes O2 from the atmosphere to
  infiltrate into the aquifer and allows oxidation
  of As bearing Pyrite (releasing As into the
  groundwater)
• As is released from the reductive dissolution of
  As-rich iron oxyhydroxide (FeOOH)

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The Answer

• Nickson et al (2000) proved that the cause of As
  contamination was by the reductive dissolution of
  As-rich Fe oxyhydroxide coated sediments

4FeOOH CH2O 7 H2CO3
4Fe2 8HCO3- 6H2O

• In areas where high As levels are found, there
  are also high amounts of bicarbonate

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The Solution

• The short-term solution is to aerate the water
  and filter the As through fresh sediment at each
  well-site

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Retrospect

• In some cases, skin lesions persisted up to 10
  years after As contamination ceased
• As contamination will remain a problem in India
  and Bangladesh for many years