Health Effects Due to Arsenic Exposure from Drinking Water

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Health Effects Due to Arsenic Exposure from
Drinking Water

• Neera Erraguntla, Ph.D.
• Toxicology Section
• Texas Commission on Environmental Quality
• nerragun_at_tceq.state.tx.us
• 512-239-2492

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Overview of Presentation

• Basics
• History
• Forms of Arsenic
• Inorganic vs. Organic
• Mediums of Arsenic Exposure
• Soil, Water, Food, and Air
• Health Effects
• Cancer vs. Non-Cancer
• Conclusions
• Q A

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What is Arsenic ?

• Arsenic (As) is an element
• This means that it is a chemical that cant be
  broken down into simpler chemicals
• Inorganic As is a human carcinogen (EPA, 1984)

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As A Global problem

• 200 million people worldwide are at risk to As
  exposure (NRC, 2001)
• Several regions in the World are above the WHOs
  maximum permissible limit. These include
• - Bangladesh - Cambodia
• - India - Vietnam
• - China - Thailand
• - Argentina - U.S.
• - Chile - Nepal
• Mexico - Ghana
• Taiwan

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History

• As linked to ancient migration
• As levels as high as 229 mg per kg
• were found in the fossils near a deep
• aquifer
• Perfect Poison for Murder
• Popular with mystery writers
• In France 1000, children died.
• They lived in rooms with wallpaper
• containing Paris Green.
• Arsine gas was the culprit

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Where does As come from?

• Natural
• As occurs naturally is widely distributed in
  the Earths crust
• Volcanic activity, rock mineral erosion,
  forest fires release As
• As is often concentrated in sulfide-bearing
  mineral deposits (e.g., gold
  and copper)
• Strong affinity to pyrite (very abundant) and
  hydrous iron oxides

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As Where does it come from?

• Anthropogenic or Man-Made
• Drilling Wells
• Mineral Extraction
• Processing Wastes
• Pesticides
• Levels of As in water depend on
• Level of human activity
• Distance from pollution sources

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US EPA

• The Safe Drinking Water Act (SDWA)
• authorizes the USEPA to set national
• health-based standards for drinking
• water to protect humans against both
  naturally occurring and man-made contaminants
  that may be found in drinking water.
• US EPA, states, and water agencies/divisions then
  work together to make sure that these standards
  are met for rivers, lakes, reservoirs, springs,
  and groundwater wells.

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Inorganic Forms of As

• Inorganic arsenic compounds are used to preserve
  wood
• In the environment, As combines with oxygen,
  chlorine, sulfur to form inorganic compounds
• Inorganic forms are toxic

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Organic Forms of As

• As in animals and plants combines with carbon and
  hydrogen to form organic arsenic compounds
• Organic arsenic compounds are used as pesticides,
  primarily on cotton plants
• Fish shellfish can accumulate organic forms
  (nontoxic)

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As in the Environment

• As can only change its form in the environment.
  It cannot be destroyed.
• As in air will settle to the ground or is washed
  out of the air by rain
• Many As compounds are easily solubilized in water
  due to changes in pH and temperature

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How might I be exposed to As ?

• Eating food, drinking water, or breathing air
  containing As
• Breathing sawdust or burning smoke from wood
  treated with As
• Living near uncontrolled hazardous waste sites
  containing As
• Living in areas with unusually high levels of As
  in rock

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What Are the Final Drinking Water Regulatory
Standards for Arsenic ?

• The enforceable Maximum Contaminant Level (MCL)
  is
• - 0.01 mg/L
• -10 micrograms per liter (µg/L)
• - 10 parts per billion (ppb)

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Human Health Effects

• Exposure to As in drinking water is reported to
  cause different human cancer and non-cancer
  diseases

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Non-Cancer Health Effects

• Long-term As exposure was found to be associated
  with cardiovascular effects (Utah and Taiwan)
• As exposure has also been reported to cause
  hypertension, anemia, liver disorders, kidney
  damage, headache, confusion.
• Among children there have been reports of
  intellectual impairment when As in drinking water
  exceeded 50 µg/L (Bangladesh)

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Non-Cancer Health Effects

• Diabetes Mellitus Dose-response relationship
  between As exposure and Diabetes (Am. J.
  Epidemiology)
• Elevated risk of keratosis and Diabetes as a
  result of long-term As exposure (Bangladesh)

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Cancer Health Effects

• Cancer Long-term Exposure (20-40 yrs)
• Skin cancer (Taiwan)
• Keratosis and Hyperpigmentation
• Blackfoot Disease (Mainly Taiwan)
• Lung cancer (Taiwan, Japan, Chile)
• Bladder cancer (Taiwan, Argentina)
• In a study conducted in the United States no
  reports of bladder cancer with average 40 µg of
  As/L in a study
• In a case control study in conducted in Western
  United States, it was found that smoking can
  elevate bladder cancer risk when drinking water
  has As levels near 200 µg/day

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Health Effects

• Keratosis

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Exposure Routes

• As exposure can occur through food, water, air,
  and medicines
• Minimal exposure through air
• Major exposure pathway is through diet
• Total Food intake 50 µg As/Day lt4 µg As/day
  from drinking water

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Metabolism of As

• Inorganic As upon ingestion is converted to two
  intermediate compounds that are more toxic than
  the parent compound (activation step)
• These intermediates are more persistent and are
  identified in the urine of individuals
  chronically exposed to As in drinking water

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Interindividual Variability

• Differences in the genetic make up determines
  whether an individual is susceptible to As
  exposure
• Differences in susceptibility to As can be due to
  differences in age, sex, and nutritional status
  (e.g. selenium can provide protection against
  diseases)
• Infants and children more susceptible

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Benefits of the New Rule

• Reducing the arsenic MCL from 50 µg/L to 10 µg/L
  will help reduce Arsenic exposure to
  approximately 13 million Americans
• Prevent 19-31 theoretical cases of bladder
  cancers per year 5-8 theoretical cases of
  deaths due to bladder cancer per year
• Prevent 19-25 theoretical cases of lung cancers
  16-22 theoretical cases of deaths due to lung
  cancer per year
• Reduce potential non-cancer effects

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Conclusions

• Public Health Can Be Severely Impacted by
  presence of elevated levels of As in drinking
  water
• ?in mortality morbidity
• Everyone is vulnerable
• Degrees of vulnerability depend on
• Biological susceptibility
• Exposure dose
• There Are Safe Levels Below Which No Adverse
  Health Effects Occur

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Take Home Message

• Collectively, we can achieve sufficient
  reductions to protect public health
• We can limit exposure, especially of susceptible
  populations
• Pregnant women
• Children