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Health Effects Due to Arsenic
Exposure from Drinking Water
Neera Erraguntla, Ph.D.
Toxicology Section
Texas Commission on Environmental Quality
[email protected]
512-239-2492
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 ?

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

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

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?

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?

Anthropogenic or Man-Made:
–
–
–
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
Drilling Wells
Mineral Extraction
Processing Wastes
Pesticides
Levels of As in water depend on:
– Level of human activity
– Distance from pollution sources
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 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

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 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 ?

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 ?
• 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
• Exposure to As in drinking water is reported to
cause different human cancer and non-cancer
diseases
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 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: 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

Keratosis
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

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

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
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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
• 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
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Biological susceptibility
Exposure & dose
• There Are Safe Levels Below Which No
Adverse Health Effects Occur
Take Home Message
• Collectively, we can achieve sufficient
reductions to protect public health
• We can limit exposure, especially of susceptible
populations
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Pregnant women
Children