Section 16 - Environmental Toxicology

Click to edit Master title style Click to edit Master text styles Second level Third level Fourth level Fifth level Click to edit Master title style Click to edit Master text styles Second level Third level Fourth level Fifth level Principles of Pharmacology and Toxicology (BIOL3020) Section 16 Introduction to Environmental Toxicology Stine and Brown (2006) Principles of Toxicology Air Pollutants Primary Pollutants Enter atmosphere directly Natural or man-made activity  Secondary Pollutants Formed after chemical modification in atmosphere Particulate Pollutants Dust, pollen and heavy metals Most come from combustion of organic matter Air Pollutants When does it cause immediate health hazard When it reaches high levels Caused by a weather condition called thermal inversion Layer of warm air traps a layer of cold air on surface Traps airborne emissions leading to high concentrations of pollutants  Health Risks Long term exposure have been implicated in development of chronic respiratory disease Can cause lung cancer Can effect plant growth and survival Gas Pollutants Carbon Oxides Carbon mon- and dioxides Carbon monoxides bind with high affinity to hemoglobin When 2 of hemoglobin get converted to carboxyhemoglobin neurological effects can be measured At 5 , cardiac output increases  Sulfur and nitrogen oxides Both pulmonary irritants Released during burning of coal and petroleum products Can react with hydroxyl radicals in atmosphere to produce sulfuric and nitric acids (acid rain) Changes pH of lakes reduce biodiversity Gas Pollutants Chlorofluorocarbons (CFCs) Used in commercial and industrial processes Propellants in aerosol cans, refrigerants, making of styrofoams Catalyze breakdown of ozone One CFC can cause breakdown of 10000s of ozone molecules Synthesis of ozone and breakdown by CFCs O O2 O3 Cl O3 ClO O2 ClO O Cl O2 Airborne Toxicants Heavy metals Arsenic, mercury, lead and cadmium Emitted from smelting (production of a metal) and other industrial applications  Pesticides Organochlorine pesticides cause health defects and environmental problems Bioaccumulate Many pesticides are neurotoxic (affect the nervous system) Many kill desirable insects or plants Contaminate streams and lakes Water Pollution Organic substances Dead and decaying plant and animal wastes Petroleum products, solvents, pesticides, polymers Inorganic substances Metals, nitrates and phosphates Biological agents Viruses, bacteria, protozoa s and other parasites that cause disease Suspended material Insoluble particles of soil/rock Radioactive material Heat Water Pollution (Examples) Organic Wastes (Sewage) If dumped into a water system aerobic bacteria may bloom Increased respiratory activities may lead to oxygen depletion in lakes (etc) Survival of other species may be affected Water Pollution (Examples) Water Pollution (Examples) More on DTT . From the family of organochlorine insecticides 1945 control of mosquitoes Serious effect on birds of prey (slow reproduction) Damaged bird eggs Now banned in NA Pesticides Enter waterways from agricultural runoff Chlorinated hydrocarbons include DDT Half life in environment is 2-3 years High lipid solubility LD50 in mammals (200 mg/kg) Cl Cl CCl3 Water Pollution (Examples) 3 3 Water Pollution (Examples) Lead Reaches lakes as it leaches from soil as industrial runoff Can come from lead pipes into drinking water, old paint, batteries Cause neurological and hematological effects Mercury Can be methylated by microorganisms into the neurotoxicant methyl mercury Toxic Waste Produced as a byproduct of Manufacturing and other industry Consumption of manufactured goods Mining Agriculture Power plant activity Small business operations (drycleaners, paint shops, automobile service) Laboratory research Household activities Categories of Waste Majority produced by large manufactures, mining and military Wastes include solvents (trichloroethylene, toluene and benzene) Polycyclic aromatic hydrocarbons Pesticides Heavy metals (lead, chromium, arsenic) Toxic Waste ( ( Is it a problem If considered cumulatively a community of many households can generate considerable waste Should attempt to manage waste responsibly The Love Canal Waste was simply disposed by burying it. Results in landfills that can leak waste into groundwater The Love Canal illustrates this Lessons Haphazard disposal is only temporary Waste Management Management can fall under the following categories Reducing amount, recycling, treatment, and storage Storage should be only temporary Reducing emphasis in industry where disposal is becoming costly Greater efficiency, alternatives, identify source Waste Management