Inorganic Arsenic Toxicity Group 6 Simon Beardmore Fionna

Inorganic Arsenic Toxicity Group 6: Simon Beardmore, Fionna Luk, Elspeth Maulit, Pavendeep Parmar, Christina Randhawa, Stipo Semren, Teresa Skyrianos, Shannon Stogryn, Jocelyn Tomkinson, Niralee Vaishnav, Nanci Voeuk, Caia Whitehead

Arsenic – history ® 6 th century Greeks documented use ® 8 th Century – first use as poison ® In medieval times, thought to be plague “charm” ® Identified as an element in the mid-1600’s ® Widespread use in Victorian times ® Discovered toxic effects in late 1800’s ® The organic arsenide Lewisite was used in chemical warfare during WWII

Arsenic – What is it? ® Element 33 on periodic table, arsenite (+3) and arsenate (+5), as well as -3 ® 20 th most abundant element in earth’s crust ® Found naturally soil, water and atmosphere ® In all living organisms ® Humans consume ~20 g/day

Arsenic – speciation ® Organic: combined with C and H Less toxic ® Found frequently in food, animals, plants ® In current use as pesticide ® ® Inorganic: combined with O, S and Cl, or other metals Most common form in rock, sediment and soil ® White (oxides), yellow and red (sulfides) ® Known carcinogen, suspected teratogen ® Common compounds: CCA, Fe. SAs ® Naturally occuring Arsenic (grey) with realgar (red) and orpiment (yellow). http: //www. portfolio. mvm. ed. ac. uk/studentwebs/session 2/group 12/

http: //www. carondelet. pvt. k 12. ca. us/Family/Science/Nitrogen/arsenic. html Inorganic Arsenic in the environment ® Soil/Sediment/Rock: ® Natural deposits/sources I. e. volcanoes, coal deposits sulfide complexes ® As a result of contamination by industrial processes: coal-fired power plants, arsenic mines, waste incineration, agricultural pollution ® Some forms are so tightly adsorbed to certain particles that plants and animals are unable to absorb the arsenic from soil and sediment

Inorganic Arsenic in the environment ® Water: ® Many types are water soluble, but As does not react with water w/o air ® Groundwater: due to agricultural or industral contamination, or where natural deposits of As are high ® Surface water: due to discharge of waste, agricultural or industrial processes or from atmosphere by dissolving in rain or snow ® Adsorbs to sediment, absorbs into aquatic biota ® Persistant in environment, some

Inorganic Arsenic in the environment ® Atmospheric: ® Found naturally in trace amounts in air ® Wide variation in atmospheric [ ] depending on location, industry, weather ® Almost exclusively due to human processes: smelting (As 2 O 3), waste incineration, coal-fired power ® Adsorbs to airborne particles, can travel long distances

What makes inorganic Arsenic toxic? ® Reversible binding with sulfhydryl groups: ® blocks Kreb’s cycle and interrupts oxidative phosphorylation. ® Inhibits cellular enzymes ®Arsenolysis: anions (-3) compete with phosphate for ADP, preventing the synthesis of ATP by the cell

Absorption and Metabolism ® The major site of absorption is the lungs or small intestine along a proton (H+) gradient. ® In plants, absorption through roots in the soil or on contact in high concentrations. ® The absorbed arsenic undergoes hepatic biomethylation to form MMA and DMAA, less toxic ® About 50% of the ingested dose may be eliminated in the urine in three to five days

Distribution and Excretion ® distributed to all body tissues, with large amounts going to the muscles (humans) or RBC’s (rats). ® 2 -4 weeks after exposure, arsenic can be found in the hair, skin and fingernails ® In plants, distributed throughout the plant body. ® Both organic and inorganic forms of arsenic are excreted from the body in the urine ® About 50% of the ingested dose may be eliminated in the urine in three to five days ® Arsenic can remain in the body for several months or longer

Routesexposure: of Exposure ® Passive eating food, drinking water, or breathing ambient air. ® Proximity to industrial or agricultural arsenic use or waste incineration ® ® Active exposure: You may also be exposed by cigarette smoke. ® occupations that involve arsenic: copper or lead smelting, wood treating, pesticide application may be exposed to above-average levels. ®

Acute Exposure Subacute: loss of appetite, fainting, nausea, vomiting, parasthesia, jaundice, dry throat, and nervous weakness. ® Longer exposure may lead to dry hair that falls out, brittle nails, eczema, liver cirrhosis, erythmatous flushing, Mee’s lines, edema ® Late effects include bone marrow depletion, abnormal heart rhythm, anemia and impaired nerve function causing parasthesia ® Death results with acute doses, from hypervolemia and GI bleeding which results in circulatory collapse; may be delayed and due to renal or liver failure ®

Chronic Exposure ® Individuals exposed to arsenic over long periods of time have increased rates of cancer ® Long term arsenic toxicity can lead to multisystem disease muscle weakness and eventually ataxia and paralysis. ® Hallmarks of chronic exposure include skin and circulatory disorders, Mee’s lines, polyneuropathy, and skin nodules on feet, hands and torso.

Treatment of Exposure exposure is treated using ® Human British anti-Lewisite, gastric lavage, and supportive therapy ® Environmental treatments include adsorption-co-precipitation using iron and aluminum salts, reverse osmosis, oxidation followed by filtration, and some kinds of distillation.

Applications of inorganic arsenic ® Forestry: Copper Chromated Arsenic (CCA) ® ~ 90% of arsenic today used as a wood preservative to prevent rotting and decaying due to insects and microbes. ® Common usage of CCA-treated wood used in both residential and industrial applications ® Arsenic leaches from CCA-treated wood products; CCA now banned use ® Agriculture: ® a herbicide to destroy weeds on cotton fields and in orchards ® an insecticide on fruits and vegetable crops and a household pesticide ® No longer used as a pesticide in agriculture due to carcinogenic properties

Other applications of inorganic arsenic ® Electronics: microwave devices, lead-acid batteries, solar cells, semiconductors, LED’s ® Glass-making: colouring & manufacture ® Medical: ® Past: used as a medicine to treat psoriasis, parasitic diseases, asthma and eczema ® Present: chemotherapy, Selenium poisoning

Human exposure ® Jamestown, 1609 -1610: >90% of the Jamestown colony perished. Scientists believe deaths were the result of arsenic poisoning at the hands of the Spanish government intent on getting rid of the English colony. ® Bangladesh: Western NGO’s instigated a massive tube well drinking-water program, and failed to test for arsenic in the groundwater. Hundreds of thousands of people are affected. It is thought to be the worst mass-poisoning in history.

Arsenic in BC: ® Canadian drinking water guideline for As is 0. 025 mg/L ® The Ministry of Water, Land Air Protection evaluated groundwater samples between 1977 and 1993 ® 2. 2% of 2100 samples analyzed had levels over 0. 025% ® High arsenic levels were found in isolated wells on Saltspring Island, the Lower Mainland near Nukko Lake