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Arsenic Almost Final Slides
The document provides an overview of arsenic, including its discovery, chemical properties, different forms (inorganic vs organic), sources (natural, anthropogenic), mechanisms of toxicity, health effects, regulation, and references for further information. It discusses how arsenic interferes with cellular processes through inhibition of enzymes and production of reactive oxygen species, leading to acute or chronic poisoning. Higher arsenic exposure has been linked to conditions like skin lesions, cancer, and reduced growth in children. Regulations set maximum limits in drinking water but food sources require further standards.
Arsenic Almost Final Slides
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- 2. Brief History ofArsenic Discovery History is convoluted Not sure who first discovered Greeks and Romans had slaves mine for arsenic Used in Alchemy Albertus Magnus www.en.wikipedia.com German chemist First to isolate in 1250 AD
- 3. General Information of Arsenic 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
- 4. Inorganic vs. Organic Arsenic Inorganic Organic Occurs naturally in soil and many minerals and ores that contain copper and lead Mainly found in marine organisms When heated, arsenic rises up smokestack as a fine dust Can still be used on agriculture Cannot be used in agriculture Primarily cotton Used to pressure treat wood Improve properties when added to Arsenate V is found in water 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
- 5. Uses of Arsenic ‘Poison of Kings’ Marsh and Reinsch Tests Bronze alloy Lead alloy Medicinal uses Syphili, yaws, psoriasis, and other viruses Industrial uses http://biologyze.com/tag/arsenic-and-bacteria/ Ammunition production, pigments, insecticides, rat poison, wood preservative, semiconductors, & others
- 6. Environmental Sources of Arsenic Marine animals In drinking water ~200 mineral species http://deepbluehome.blogspot.com/2010/10/deep-blue-home- snapshot-2000-2010.html Most common is arsenopyrite Emitted from volcanoes http://ebt2010.blogspot.com/2010/07/understand-whats- arsenic-and-how-it.html http://www.ecowaternorthwest.com/arsenic.php
- 7. Anthropogenic Sources of Arsenic Reduction of Arsenic Trioxide (As2O3 - Arsenite) with charcoal As2O3 is created during the metal smelting process Industrial uses http://www.ehow.com/how_6160537_preserve-pressure-treated-wood.html Ammunition production, pigments, insecticides, rat http://www.indiamart.com/alchemylaboratories /analytical-reagents.html poison, wood preservative, semiconductors, & others http://serc.carleton.edu/woburn/issues/pesticides.html
- 8. Mechanism Inorganic Arsenate – exists in +5 oxidation state Arsenite – exists in +3 oxidation state
- 9. Mechanism (Continued) Organic As – methylated (both in +3 oxidation state) Monomethylarsonous acid (MMAIII) Dimethylarsinous acid (DMAIII)
- 10. Mechanism (Continued) + 5oxidation state (pentavalent) + 3 oxidation state (trivalent) Arsenate Monomethylarsonous acid (MMAIII) Dimethylarsinous acid (DMAIII) Arsenite
- 11. Mechanism (Continued) In general, As terrorizes the metabolic processes of the mitochondria http://www.phschool.com/science/biology_place/biocoach/cellresp/overview.html
- 12. Mechanism (Continued) Pentavalent toxicity Very similar to phosphate Can substitute for inorganic phosphate in glycolytic and cellular respiration pathways
- 13. Mechanism (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
- 14. Mechanism (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
- 15. Mechanism (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
- 16. Mechanism (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
- 17. Mechanism (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
- 18. Mechanism (Continued) Carcinogenicity ROS accumulation DNA Excision Repair and DNA Ligase inhibited by Arsenic Co-mutagenic effect with ROS, UV radiation, http://www.biol.unt.edu/~jajohnson/DNA_sequencing_process X-Rays, and other chemicals DNA methylation alterations Also noted as a tumor promoter in mouse ovarian cancers
- 19. Health Effects and Symptoms Acute As poisoning Nausea Vomiting Blood in the urine Cramping muscle Hair loss Stomach pain Convulsions Organ failure Comma to death (interferes with glycolysis)
- 20. Health Effects and Symptoms 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 http://wewinwater.com/2011/09/03/addressing-arsenic-poisoning-in-bangladesh/ Blushed complexion
- 21. Health Effects and Symptoms 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/
- 22. Health Effects and Symptoms 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
- 23. Health Effects and Symptoms 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 http://romanianrecipes.wikia.com/wiki/Milk blurred vision, hard of hearing, low score in school record, abnormal brainwave, epilepsy, headache, dizziness, cold hands and feet
- 24. Health Effects and Symptoms 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
- 25. Health Effects and Symptoms 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.
- 26. Arsenic Regulation & Legislation 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
- 27. Arsenic Regulation & Legislation 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
- 28. Arsenic Regulation & Legislation 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
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