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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@tceq.state.tx.us 512-239-2492. Overview of Presentation. Basics History Forms of Arsenic Inorganic vs. Organic

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health effects due to arsenic exposure from drinking water

Health Effects Due to Arsenic Exposure from Drinking Water

Neera Erraguntla, Ph.D.

Toxicology Section

Texas Commission on Environmental Quality

nerragun@tceq.state.tx.us

512-239-2492

overview of presentation
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
what is arsenic
What is Arsenic ?
  • Arsenic (As) is an element
    • This means that it is a chemical that can’t be broken down into simpler chemicals
  • Inorganic As is a human carcinogen (EPA, 1984)
as a global problem
As: A Global problem
  • 200 million people worldwide are at risk to As exposure (NRC, 2001)
  • Several regions in the World are above the WHO’s maximum permissible limit. These include:

- Bangladesh - Cambodia

- India - Vietnam

- China - Thailand

- Argentina - U.S.

- Chile - Nepal

    • Mexico - Ghana
    • Taiwan
history
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

where does as come from
Where does As come from?
  • Natural:
    • As occurs naturally & is widely distributed in the Earth’s 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
as where does it come from
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
us epa
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.
inorganic forms of as
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
organic forms of as
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)
as in the environment
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
how might i be exposed to as
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
what are the final drinking water regulatory standards for arsenic
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)

human health effects
Human Health Effects
  • Exposure to As in drinking water is reported to cause different human cancer and non-cancer diseases
non cancer health effects
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)
non cancer health effects1
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)
cancer health effects
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
health effects
Health Effects
  • Keratosis
exposure routes
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; <4 µg As/day from drinking water
metabolism of as
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
interindividual variability
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
benefits of the new rule
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
conclusions
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
take home message
Take Home Message

Collectively, we can achieve sufficient reductions to protect public health

We can limit exposure, especially of susceptible populations

Pregnant women

Children