ARSENIC-PPT............................ppt

Arsenic

1. ARSENIC
A PERFECT POISON
PRESENTED BY
SUSNATA
SAYAN
SANDIP
PRONOY

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 Asis 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
Aslinked 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 Ascome from?
Natural:
Asoccurs naturally & is widely distributed in
the Earth’s crust
Volcanic activity, rock & mineral erosion, &
forest fires release As
Asis 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 Asin 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
Asin 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. Asin the Environment
Ascan only change its form in the environment.
It cannot be destroyed.
Asin air will settle to the ground or is washed out
of the air by rain
Many Ascompounds 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 Asin
rock

13. 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)

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

15. Non-Cancer Health Effects
Long-term Asexposure was found to be
associated with cardiovascular effects (Utah
and Taiwan)
Asexposure has also been reported to cause
hypertension, anemia, liver disorders, kidney
damage, headache, & confusion.
Among children there have been reports of
intellectual impairment when Asin 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)
Keratosisand Hyper pigmentation
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 Aslevels
near 200 µg/day

18. Health Effects
Keratosis

19. Exposure Routes
Asexposure 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 Asupon 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 Asin drinking water

21. Inter individual Variability
Differences in the genetic make up determines
whether an individual is susceptible to As
exposure
Differences in susceptibility to Ascan 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 Asin 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

25. THANK YOU