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Health Effects Due to Arsenic Exposure from Drinking Water

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Presentation on theme: "Health Effects Due to Arsenic Exposure from Drinking Water"— Presentation transcript:

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

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