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Arsenic
Brief History of Arsenic Brief History of Arsenic DiscoveryDiscovery
History is convoluted Not sure who first discovered
Greeks and Romans had slaves mine for arsenic
Used in Alchemy
Albertus Magnus German chemist First to isolate in 1250 AD
www.en.wikipedia.com
General Information of General Information of ArsenicArsenic
Chemical Formula = As
Atomic Number = 33
Molecular Weight = 74.92 grams
Color = lead gray, gray, white
Hardness of 3.5 Similar to calcite or flourite Talc is 1 and diamond is 10
Nonmagnetic
Metallic
Poor conductor of heat & electricity
http://periodictable.com/Elements/033/index.html
Inorganic vs. Organic Inorganic vs. Organic ArsenicArsenic
Inorganic
Occurs naturally in soil and many minerals and ores that contain copper and lead
When heated, arsenic rises up smokestack as a fine dust
Cannot be used in agriculture
Used to pressure treat wood
Arsenate V is found in water
Organic
Mainly found in marine organisms
Can still be used on agriculture Primarily cotton
Improve properties when added to an allow or metal
Greatest use in lead acid batteries
Semiconductors and LED’s
Arsenate III found in water
http://www.finegardening.com/design/articles/pressure-treated-wood-in-beds.aspx
Uses of ArsenicUses of Arsenic ‘Poison of Kings’
Marsh and Reinsch Tests
Bronze alloy
Lead alloy
Medicinal uses Syphili, yaws, psoriasis, and other viruses
Industrial uses Ammunition production, pigments, insecticides,
rat poison, wood preservative, semiconductors, & others
http://biologyze.com/tag/arsenic-and-bacteria/
Environmental Environmental Sources of ArsenicSources of Arsenic
Marine animals
In drinking water
~200 mineral species Most common is arsenopyrite
Emitted from volcanoes
http://deepbluehome.blogspot.com/2010/10/deep-blue-home-snapshot-2000-2010.html
http://ebt2010.blogspot.com/2010/07/understand-whats-arsenic-and-how-it.html
http://www.ecowaternorthwest.com/arsenic.php
Anthropogenic Anthropogenic Sources of ArsenicSources of Arsenic
Reduction of Arsenic Trioxide (As2O3 - Arsenite) with charcoal As2O3 is created during the
metal smelting process
Industrial uses Ammunition production,
pigments, insecticides, rat poison, wood preservative, semiconductors, & others
http://www.ehow.com/how_6160537_preserve-pressure-treated-wood.html
http://serc.carleton.edu/woburn/issues/pesticides.html
http://www.indiamart.com/alchemylaboratories/analytical-reagents.html
MechanismMechanism
Inorganic Arsenate – exists in +5 oxidation state
Arsenite – exists in +3 oxidation state
Mechanism Mechanism (Continued)(Continued)
Organic As – methylated (both in +3 oxidation state)
Monomethylarsonous acid (MMAIII)
Dimethylarsinous acid (DMAIII)
Mechanism Mechanism (Continued)(Continued)
+ 5 oxidation state (pentavalent) + 3 oxidation state (trivalent)
Arsenate Monomethylarsonous acid (MMAIII)
Dimethylarsinous acid (DMAIII)
Arsenite
Mechanism Mechanism (Continued)(Continued)
In general, As terrorizes the metabolic processes of the mitochondria
http://www.phschool.com/science/biology_place/biocoach/cellresp/overview.html
Mechanism Mechanism (Continued)(Continued)
Pentavalent toxicity
Very similar to phosphate
Can substitute for inorganic phosphate in glycolytic and cellular respiration pathways
Mechanism Mechanism (Continued)(Continued)
Pentavalent toxicity
ADP-phosphate = ATP
ADP-arsenate = biologically useless
High energy phosphate bonds are lost
Stopping the production of ATP will stop all processes that require ATP
Mechanism Mechanism (Continued)(Continued)
Trivalent toxicity
Reacts readily with thiol-containing molecules (-SH functional group) Amino acid cysteine contains thiol group Cysteine rich proteins are vulnerable to As
binding but if binding does not have detrimental effects on the protein, this may serve as a detoxification mechanism
Mechanism Mechanism (Continued)(Continued)
Trivalent toxicity
Pyruvate Dehydrogenase (PDH) requires lipoic acid cofactor – a dithiol
As inhibits this enzyme by binding to the cofactor
The citric acid cycle cannot proceed because the pathway is terminated
http://upload.wikimedia.org/wikipedia/commons/0/0b/Citric_acid_cycle_with_aconitate_2.svg
Mechanism Mechanism (Continued)(Continued)
Oxidative Stress
Reductase enzymes are present in the cell to reduce reactive oxygen species (ROS)
As binds and inhibits some of these reductases, resulting in the accumulation of ROS
ROS can bind/damage DNA and other cellular components Part of As carcinogenicity
Mechanism Mechanism (Continued)(Continued)
Carcinogenicity
Researchers have yet to fully elucidate carcinogenic mechanisms of As
It is widely accepted that As is a carcinogen and several mechanisms have been proposed
Mechanism Mechanism (Continued)(Continued)
Carcinogenicity
ROS accumulation
DNA Excision Repair and DNA Ligase inhibited by Arsenic
Co-mutagenic effect with ROS, UV radiation, X-Rays, and other chemicals
DNA methylation alterations
Also noted as a tumor promoter in mouse ovarian cancers
http://www.biol.unt.edu/~jajohnson/DNA_sequencing_process
Health Effects and Health Effects and SymptomsSymptoms
Acute As poisoning Nausea Vomiting Blood in the urine Cramping muscle Hair loss Stomach pain Convulsions Organ failure Comma to death (interferes with glycolysis)
Health Effects and Health Effects and SymptomsSymptoms
Chronic arsenic poisoning High oxidative stress
affect the structure of function of cardiovascular system
Increases the risk of cancer Vitamin A deficiency
Night blindness Heart disease
Skin color change Eye inflammation Hyperkeratosis and hyperpigmentation
Blushed complexionhttp://wewinwater.com/2011/09/03/addressing-arsenic-poisoning-in-bangladesh/
Health Effects and Health Effects and SymptomsSymptoms
Bangladesh 77 million people (1/2 population of crowded
Bangladesh) may have been exposed to toxic levels of arsenic.
More than 20% of deaths are caused by arsenic.
Groundwater is contaminated with As
http://www.who.int/topics/arsenic/en/
Health Effects and Health Effects and SymptomsSymptoms
United Kingdom (1990 and 1991) In UK, 6000 people had the arsenic poisoning
and 70 of them died. The beer contained 15ppm of arsenic
Glucose (ingredient of beer) is contaminated to arsenic
Contaminated during the refining process
http://www.beer100.com/beercalories.htm
Health Effects and Health Effects and SymptomsSymptoms
Japan (1955) In Japan, 12,130 children suffered from the arsenic
poisoning and 130 of them died. Milk from Tokushima factory was contaminated to
arsenic Symptoms
loss of appetite, vomiting, diarrhea, boil, skin color changed to black, anemia, hypertrophy of the liver
Aftereffect blurred vision, hard of hearing, low score in
school record, abnormal brainwave, epilepsy, headache, dizziness, cold hands and feet
http://romanianrecipes.wikia.com/wiki/Milk
Health Effects and Health Effects and SymptomsSymptoms
Arsenic and ADHD study (Roy et al 2010) 526 6-7 years old children in Torreon Mexico
Urinary arsenic levels were measured
No significant relationship found between any measure of urinary arsenic and parents ratings of behavior
However, higher urinary arsenic was associated with high scores on Cognitive Problem exams
Health Effects and Health Effects and SymptomsSymptoms
Pre- and Postnatal Arsenic Exposure and Body Size – a cohort study (Saha et al 2012) Purpose - to assess potential effects of early
life As exposure on weight and length of children from birth to 2 years of age
2372 children born in Bangladesh. Measured arsenic concentrations in urine (U-As) with
child body weight and length Compared to girls in the first quintile of U-As (<16
µg/L), those in the fourth quintile (26-46 µg/L) were almost 300 g lighter and 0.7 cm shorter.
Postnatal arsenic exposure was associated with lower body weight and length among girls, but not boys.
Arsenic Regulation & Arsenic Regulation & LegislationLegislation
EPA Proposed a maximum contaminant level (MCL)
of 5mcg/L in 2000 and established at 10mcg/L on Jan 22, 2001
This rule became enforceable on Jan 23, 2006
This standard protects public health based on the best available science and ensures that the cost of the standard is achievable
Arsenic Regulation & Arsenic Regulation & LegislationLegislation
FDA Currently only has a standard for maximum levels of As in
bottled water
No inorganic As regulations in Europe and U.S. in relation to food
Only China has a regulatory limit (150 ppb)
Today, FDA is testing apple juice and trying to determine an appropriate level
Apple juice containing >23 ppb of organic arsenic represent a potential health risk
Arsenic Regulation & Arsenic Regulation & LegislationLegislation
Organic Food Organic food is not exempt from being
contaminated by toxic chemicals
Organic standard do not prohibit the presence of As
Two brands of organic infant formula – 20 times more As than other regular brands
Institute for Agriculture and Trade Policy (IATP) and FDA move toward regulating As contaminant levels in the food supply
References References http://www.sciencedirect.com/science/article/pii/S037842740200084X
http://emedicine.medscape.com/article/812953-overview#a0104
http://www.sciencedirect.com/science/article/pii/S0013935111000739
http://www.ncbi.nlm.nih.gov/pubmed/22504586
http://www.who.int/bulletin/archives/78(9)1093.pdf
http://www.ehjournal.net/content/5/1/31