1. Health Effects Due to Arsenic Exposure from Drinking Water
Neera Erraguntla, Ph.D.
Toxicology Section
Texas Commission on Environmental Quality

2. 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

3. 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)

4. 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

5. 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

6. 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

7. 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

8. 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.

9. 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

10. 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)

11. 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

12. 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

13. What Are the Final Drinking Water Regulatory Standards for Arsenic ?
The enforceable Maximum Contaminant Level (MCL) is
mg/L
-10 micrograms per liter (µg/L)
- 10 parts per billion (ppb)

14. Human Health Effects
Exposure to As in drinking water is reported to cause different human cancer and non-cancer diseases

15. 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)

16. 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)

17. 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

18. Health Effects
Keratosis

19. 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

20. 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

21. 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

22. 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

23. 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

24. Take Home Message
Collectively, we can achieve sufficient reductions to protect public health
We can limit exposure, especially of susceptible populations
Pregnant women
Children