Transcript Slide 1
Organic Chemicals and Water Synthetic Organic Chemicals Principally Carbon, Hydrogen and Oxygen Organochlorines Dioxins Pesticides Chlordane Dioxin PCBs Cleaning agents DDT PBDE Flame Retardants Potential Toxicity July November 2004 Viktor Yushchenko Ukrainian President 6,000 times the usual concentration in his body the second highest dioxin level ever measured in a human Water Solubility Organochlorines as well as many other synthetic organic compounds are poorly soluble in water NaCl Na+ + Cl- Dioxin Dioxin 0.2 µg/L PCB 10-31 µg/L (50% Cl) Sodium Chloride 350 g/L Potassium Chloride 280 g/L Ionic compounds are about 1 billion times more water soluble than neutral organics Improving Solubility Organic Solvents Soap/detergents Structural/chemical similarity between the chemical and the solvent. Hexane Lipids and Solubility Structural/chemical similarity between the chemical and the solvent. Solubility A chemical’s solubility in lipids is inversely proportional to its solubility in water. Lipid (Carbon/hydrogen) Carbon/hydrogen water Toxaphene Biomagnification Seawater Arctic cod muscle Narwhal blubber 0.0003 ppb 14 - 46 ppb 2440 - 9160 ppb BAF = 8 million What’s been done? PCBs used extensively in electrical equipment, especially transformers Solubility: 10-31 µg/L PCBs, valued for chemical stability and fire resistance, were manufactured and processed primarily for use as insulating fluids and coolants in electrical equipment and machinery from 1929-1977. Electrical equipment plasticizers in paints, plastics and rubber products pigments, dyes and carbonless copy paper PCBs were “banned” in 1979 [EPA press release - April 19, 1979] The Environmental Protection Agency today issued final regulations banning the manufacture of polychlorinated biphenyls (PCBs) and phasing out most PCB uses. PCBs are toxic and persistent chemicals primarily used as insulating fluids in heavy-duty electrical equipment in power plants, industries, and large buildings across the country. The EPA rules will gradually end many industrial uses of PCBs over the next five years, but will allow their continued use in existing enclosed electrical equipment under carefully controlled conditions. EPA estimates that 150 million pounds of PCBs are dispersed throughout the environment, including air and water supplies; an additional 290 million pounds are located in landfills in this country Spokane River Nov. 2002 Lake Michigan EPA, 2004 N Concentration PCBs µg PCB/Kg sediment Lake Erie Sediments PCBs EPA, 2004 After 25 years, PCBs continue to persist in the Environment Persistent Organic Pollutants Poor water solubility High solubility in Lipids and Organic Solvents Potentially long half lives DDT PCB Dioxin Half Life ½ Life The time it takes for a chemical to degrade To ½ of its original concentration. Ci ½ Ci t1/2 time ½ Life and Organochlorines PCBs 1 month 2-6 years > 60 years Dioxin 1 - 30 years (7 years in humans) DDT 28 days 15 – 20 years up to 150 years Environmental Persistence Water Column Solubility of < 0.2 μg/L Short Half life Sediments (longer half-life) Environmental Persistence, Half Life and Solubility An Important Organic Solvent: Octanol C8H18O Neutral organic chemicals are soluble in organic solvents The Octanol-Water Partitioning coefficient C8H18O Octanol and water are immiscible Density: 0.824 g/cm3 octanol water C8H18O Partitioning Carbon/hydrogen Octanol (Carbon/Hydrogen) water C10H20 Add 10 mg chemical 1 L Octanol 1L Water separate chemical chemical Analyze the water phase for the chemical. Difference between initial amount and amount in water = amount in octanol The ratio between the two yields the Kow Add 10 mg chemical 1 L Octanol 1L Waterl separate chemical chemical 0.01 mg L Water phase 9.99 mg L octanol phase Kow = 9.99 mg L 0.01 mg L = 999 Kow of some Organochlorine Compounds PCBs 2,000,000 DDT 4,000,000 Dieldrin 158,000 Toxaphene 316,000 Environmental Persistence Water Column Solubility of < 0.2 μg/L Short Half life Sediments (Carbon)