Lecture 9: Arsenic PDF

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Lecture on the adverse effects of arsenic. Taught by professor Michele La Merrill...

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Arsenic and Old Lace Intro to Environmental Toxicology Lecture 18

What is Arsenic? 1. Metalloid, clear when dissolved 2. Arsenic exposure: poisonings Harassing Agents 1. Vomiting agents include diphenylcyanoarsine and diphenylchloroarsine 2. First synthesized by Germany during WW1, not extensively used in combat 3. Containing arsenic, cause nausea, vomiting, headaches How to Deal With Arsenic Poisoning 1. Chelating agents bind to metals and metalloids such as arsenic 2. During WW2, chemists at University of Oxford secretly identified Dimercaprol (British anti-Lewisite, BAL) as an antidote for lewisite, an arsenic based chemical weapon 3. BAL was the first chelation therapy used by medical toxicologists 4. BAL is toxic, narrow therapeutic index, causing nephrotoxicity and hypertension. 5. 1960’s - BAL modified to DMSA, related dithiol with far fewer side effects 6. DMSA quickly replaced BAL as the primary treatment for arsenic poisoning in the United States Characteristics of an Ideal Chelator 1. Greater affinity (binds to metal more tightly) than natural substances 2. Low toxicity 3. Ability to penetrate cell membranes 4. Rapid elimination of the toxic metal 5. High water solubility 6. Same distribution in tissues of the body as the metal Occupational Exposures 1. Smelters, miners, pesticides, pood treatment, semiconductor… (workers and neighbors) Arsenic Pesticide Use in California 1. Arsenic Wood Treatment to Prevent Termites 1. 70% of homes in US have decks or porches with chromated copper arsenate (CCA) 2. 14% of public playgrounds have CCA wood structures 3. New use banned since 2004 4. Old structures still present 5. Wet wood leaches 3x more arsenic than dry wood Arsenic in Rice 1.

Arsenic and Old Lace Intro to Environmental Toxicology Lecture 18

Arsenic Exposure 1. Most arsenic exposure though naturally contaminated groundwater 2. Arsenic levels in the US public drinking water supply chart 3. Private well water and reverse osmosis filter use a. Pre-filter HIGH AF post-filter SUPER low! 4. Over 200 million individuals worldwide chronically exposed to arsenic in drinking water above 10 ppb standard, 1.7 million in the US Acute Poisoning (Rapid ingestion of inhalation of high doses) 1. Nausea and vomiting 2. Diarrhea 3. Hemolysis 4. Shock 5. Death 6. Suicide, homicide, occupational poisonings 7. Rx: if very high dose and acute life-threatening health effects: chelating agents. 8. Induction vs latency period Chronic Exposure of Arsenic (long term intake of lower doses) 1. Cardiovascular disease (blackfoot disease, heart disease) 2. Skin lesions 3. Cancer (bladder, lung, skin, kidney) 4. Diabetes 5. Lung disease 6. Reproductive effects 7. Cognitive effects in children Epidemics of High Exposure from Drinking Water - 20th century 1. Southwestern Taiwan a. 130,000 people drank water over 50 years highly contaminated with arsenic i. Widespread skin cancer 2. Northern Chile a. Antofagasta region (400,000 population) supplies with river water high in arsenic for about 30 years i. High incidence of bladder, skin, lung cancer 3. India (West Bengal) and Bangladesh a. Government drilled shallow wells to provide clean water starting in late 1960’s. In 1980’s problems appeared i. 30 million people risk developing serious medical problems b. Keratosis, hyperpigmentation, males more affected than females 4. Antofagasta (population 296,905) a. 1958 - high arsenic river water diverted into city b. 1970 - arsenic treatment plan installed

Arsenic and Old Lace Intro to Environmental Toxicology Lecture 18

c. 1 million individuals exposed to over 800 u/liter 5. How long do cancer rates remain elevated after high exposures have ended? a. 38 years 6. Lung cancer odds ratios, stratified by age of earliest high arsenic exposure Why are these studies important? 1. Millions of people still exposed 2. Most regulations based on data from healthy adults 3. Very little data on long-term impacts of early life exposures or other susceptibility factors...