Toxic Bioaccumulative Chemicals

Most mercury enters aquatic environments from the atmosphere The dominant inorganic forms are Hg o and Hg 2+. Positively charged Hg 2+ can become attached to negatively charged organic and inorganic particles in soils and sediments which tends to immobilize them. Under anaerobic conditions, Hg 2+ can be converted to organic Methylmercury which is more toxic and persistent in organisms. Mercury methylation is related to the metabolism of Sulfur-reducing bacterial under anaerobic conditions The exact biochemical mechanism is poorly understood. High sulfur concentrations increase mercury methylation Mercury

The following are required for mercury methylation Inorganic Mercury Anaerobic Conditions Carbon Source (sediments) Sulfate/Sulfate-Reducing Bacteria Methylmercury is more directly toxic and remains in The tissues of organisms longer than inorganic Hg 2+. This allows methymercury to bioaccumulate in organisms Bioaccumulation allows for biomagnification which is the increase in concentration of a chemical in organisms higher up in the food chain. Bioaccumulation occurs when an organism absorbs a toxic substance at a rate greater than that at which the substance is lost from the body.

Biomagnification: concentration of a chemical in organisms as it moves up the food chain. Organisms near the top of the food chain may have concentrations of mercury millions of times greater than in the aquatic environment

Other Bioaccumulative Toxins Synthetic Organic Chemicals

Dioxins Pesticides PCBs Flame Retardants PBDE Dioxin PCB DDT Organochlorines Organic = carbon-rich compounds

Viktor Yushchenko Ukrainian President Potential Toxicity 6,000 times the usual concentration in his body July November the second highest dioxin level ever measured in a human 2004

Chemicals like dioxin are acutely toxic In high doses, but they also can bioaccumulate creating chronic toxicity at lower doses The cause of their ability to bioaccumulate is related to their water solubility.

Sodium Chloride350 g/L Potassium Chloride280 g/L Water Solubility Why? NaClNa + + Cl -

Water Molecules are Polar Unequal distribution of electrons Oxygen is electron-greedy

NaClNa + + Cl - Na + Cl - Sodium Chloride water solubility: 350 g/L

Contrast with Organic Chemicals

Organic Chemicals Greases, Oils, Paints, Pesticides, Industrial Chemicals Grease and Oil Carbon83 to 87% Hydrogen10 to 14% C 16 H 14 OS Oil Paint Composed mostly of carbon and hydrogen, and possessing no electrical charge. Carbon-rich compounds

Dioxin PCB DDT Principally carbon, hydrogen C 11 H 18 O 2 Cl 4 C 14 H 22 Cl 5 C 12 H 21 Cl 2 Do not possess an electrical charge

Dioxin Dioxin water solubility: 0.2 µg/L

Dioxin PCB DDT 10 µg/L 0.2 µg/L Uncharged and principally carbon, hydrogen < 0.1 µg/L

Toxaphene: 3 mg/L Dieldrin: 186 ug/L Chlordane: 9 ug/L

These types of chemicals are poorly soluble in water In what substances do they dissolve? Greases, Oils, Paints, Pesticides, Industrial Chemicals

Hexane D-limonene oil Common Organic Solvents Carbon-based petroleum

Organic Solvents water Hexane Acetone Lipids Carbon-based compounds dissolve more easily in carbon- based solvents. carbon Dioxin

- SO 4 Soap hydrophobic hydrophilic SO 4 - High Carbon Concentration

Bioaccumulation in Organisms

Fundamental similarity between the chemical and the solvent. Bioaccumulation in Organisms Lipid Tissue in Organisms The chemical essentially dissolves into the lipid tissues carbon

Synthetic organic chemicals are poorly soluble in water They are soluble in organic solvents and lipids Lipids are found in all organisms Despite low levels of organic chemicals in water due to their low water solubility, high amounts can accumulate in the tissues of living organisms

Magnification of 800 x Water Concentration = 0.2μg/L Zooplankton concentration = 160 μg/L

Bio-Magnification Water and phytoplankton to zooplankton: 800 x Zooplankton to fish: 31 x Overall: 120,000 times original concentration in water Fish to eagle: 4.8x

PCBs and Pesticides

PCBs Electrical equipment plasticizers in paints, plastics and rubber products pigments, dyes and carbonless copy paper PCBs were “banned” in 1979 Used as insulating fluids and coolants in electrical equipment and machinery from 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 some PCBs act like hormones, and other PCBs are nerve poisons

PCBs in Marine Mammals Hazardous Waste level (Canada) Killer Whales (1000 ppm) High on food chain Lipid tissues

Seawater Arctic cod muscle Narwhal blubber ppb ppb ppb Toxaphene 50,000 X ~ 8 M X carbon lipid 400,000 tons: 1946 to 1974 (670 chemicals)

Toxaphene and Mirex: highest levels ever recorded in a living organism.

1.Many synthetic organic chemicals are uncharged. 2. Because they are uncharged, they do not permit orientation of water molecules and are poorly soluble in water. 3. Ionic compounds (e.g. NaCl) are about 1 billion times more water-soluble than uncharged organics. 4. Uncharged organic chemicals, however, tend to be soluble in organic solvents and organic materials because of similar carbon-based chemistry. 5. These materials can include lipid tissues in organisms which can lead to biomagnification Summary

Solubility water Hexane Acetone Lipids Carbon-based compounds dissolve more easily in carbon- based solvents. carbon Dioxin

Where in these environments do we find high levels of carbon? Many synthetic organic chemicals, particularly those like PCBs and DDT are very persistent in the environment. They last for decades. They become stored in organic materials that naturally occur in aquatic and terrestrial systems

Carbon Hydrogen Oxygen Organic Matter Coiled and convoluted chains of carbon, hydrogen, and oxygen

Carbon Hydrogen Oxygen Organic Matter COOH OH carboxylic enolic C C C C C C C C C C C C C C C H H H H H H H H H H H H H

Partitioning/Distribution Organic matter Soil Solution Absorption

Partitioning of neutral organic chemicals into soil organic matter limits their mobility in the environment

Aquatic Systems

Water Organic Sediments Environmental Persistence Solubility of < 0.1 μg/L Organic chemicals become stored in organic sediments This protects them from degradation and increases their lifetime in the environment DDT

Lake Michigan µ g PCB/Kg sediment (parts per billion) EPA 2004 mg Carbon /g sediment N Concentration Organic Carbon PCBs “banned” in 1979 Open water PCB concentration = < 1 part per trillion

Lake Erie PCB levels PCBs After 30 years, PCBs continue to persist in the Environment EPA, 2004

Persistence in the Environment Old sediments

Florida and Organic Chemicals

DDT dichloro-diphenyl-trichloroethane First Modern Pesticide Insecticide developed to combat insect-borne disease Use was later expanded to include agriculture

DDT levels ranging from 2,200 to 110,000 µg/kg (ppb) in organic soils and sediments. Rita Island, Okeechobee Organic soils

Historically characterized by clear water and a highly prized sports fishery, it served as a popular destination for boaters, swimmers, and fishermen for decades. Lake Apopka 30,800 acres mean depth is 5.4 feet 15 miles northwest of Orlando

In the 1970s, scientists considered Lake Apopka a prime place to harvest eggs and hatchlings to study them in captivity. In 1980 and 1981, scientists counted populations of 1,200 to 2,000 alligators in a single night on the lake By the late 1980s, they counted only 150 per night

Agriculture Pesticide Use in Agricultural Area Pesticide use included high amounts of DDT

"Lake Apopka is a big chemical soup," Michael Fry, a researcher from the University of California Tower Chemical Company Produced dicofol, a mixture of the pesticide DDT and DDE, a by-product of DDT. Periodic spills occurred there, but a particularly large accident in 1980 caused dicofol to spread into the lake TOC content ranges from 33 to 37%

Apopka's juvenile alligators have abnormal testes and ovaries and abnormal hormone balances DDE, a breakdown product of DDT, is a major contaminant in Lake Apopka DDE is known to block the action of testosterone Alligator Population crash was linked to poor egg viability Estradiol Testosterone Apopka males had high levels of estradiol relative to testosterone

' Teeny Weenies ' Alligators in Florida's Lake Apopka have Smaller Penises Kyla Dunne for PBS June,

Solubility water Hexane Acetone Lipids Carbon-based compounds dissolve more easily in carbon- based solvents. carbon Dioxin

What is the most common way we daily dissolve organic substances/chemicals?

- SO 4 Soap hydrophobic hydrophilic SO 4 - High Carbon Concentration

Soap SO 4 - Oil drop in water Soap micelle

Assessing the Danger: Octanol

An Important Organic Solvent:Octanol C 8 H 18 O Neutral organic chemicals are soluble in organic solvents c c c c c c c c

Octanol-Water Partitioning Octanol and water are immiscible Octanol Density: g/cm3 octanol water C 8 H 18 O

Octanol (Carbon/Hydrogen) water Carbon/hydrogen Partitioning Between Octanol and Water C 10 H 20

Octanol-Water Partitioning Coefficient Kow = Concentration of chemical in octanol Concentration of chemical in water At equilibrium

water 1 L Octanol 1L Water Add 10 mg chemical separate 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 K ow octanol

Add 10 mg chemical separate chemical 0.01 mg L 9.99 mg L Water phase octanol phase Kow = 9.99 mg L 0.01 mg L = L Octanol 1L Waterl

K ow of some Organochlorine Compounds DDT 4,000,000 PCBs 2,000,000 Dioxin6,000,000 A high Kow indicates strong interaction with organic solvents and lipid tissues chemical in octanol chemical in water

PCBs Electrical equipment plasticizers in paints, plastics and rubber products pigments, dyes and carbonless copy paper Kow = 2,000,000 PCBs were “banned” in 1979 Used as insulating fluids and coolants in electrical equipment and machinery from 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 some PCBs act like hormones, and other PCBs are nerve poisons

DDT first modern pesticide (Nobel Prize, 1948) Insoluble in water. Soluble in most organic solvents, fat, and oils. used with to combat mosquitoes spreading malaria (mosquitoes), and typhus (lice) Banned in 1972 (U.S.) Kow = 4,000,000

Launch of the Environmental Movement 1962 human volunteers ingested 35 mg of DDT primates were fed 33,000 times more DDT than the estimated exposure Thinning egg shells Lower hatching rates Declining Eagle population Carcinogenic decline in the eagle population occurred before the DDT years (bounties between 1917 and 1942)

Simple Filtration Carbon (most common component) Ion Removal Water Filters

Activated Carbon Activation by heating Extremely porous with high surface area: 500 m 2 /g Large surface area = high contact with contaminants

Activated Carbon Absorption: spontaneous movement of primarily organic contaminants from water to carbon matrix. Pesticides and other organics essentially dissolve in the carbon Chlorine sticks to the extensive surfaces

2,4-D TP (Silvex) Alachlor Atrazine Carbofuran Chlordane Endrin Heptachlor Epoxide Lindane Methoxychlor Simazine Toxaphene Benzene Carbon Tetrachloride Chlorobenzene Ethylbenzene Monochlorobenzene MTBE O-Dichlorobenzene P-Dichlorobenzene Styrene Tetrachloroethene Toluene Trichloroethene VOCs Antidepressants Steroids/Hormones Prednisone, Prednisolone, Progesterone, Testosterone, Cortisol/Hydrocortisone Antibiotics Ciprooxacin, Trimethroprin, Sulfamethoxazole Anxiolytics Meprobamate Carbon Filter Removal Does not remove bacteria or most metals