Dioxin and Backyard Burning Vermont Forum on Open Burning May 17, 2004 Mark Mahoney EPA New England Topics What is dioxin? Why is dioxin a unique pollutant? Health Effects Exposure Pathways Environmental Sources Importance of Barrell Burning 2 Some consider this an issue of the past. 3
4 5 6 7 State-of-the-Art Burn Box 8 Why are we Concerned? Backyard burning causes accidental fires. Backyard burning releases toxic chemicals into environment that can cause adverse health impacts. Backyard burning is illegal in many states and counties. 9 Release of Toxic Chemicals
3,3',4,4'-TeCB 3,3',4,4',5-PeCB 3,3',4,4',5,5'-HxCB Plus 8 others 11 What is Dioxin? A group of chlorinated organic compounds including dioxins, furans, and some PCBs. Produced when materials containing chlorine are burned Occur naturally and from combustion of fuels & waste, paper making, and other chemical and industrial processes. 12 USEPAs Dioxin Reassessment The Good News: The average bioaccumulation level in humans has dropped from 55 ppt (in the 1980s) to 25 ppt (1990s)
The Bad News: The level at which health effects are detectable in humans is considerably lower than previously estimated. Consequently, current exposures are still of concern. The Bottom Line: We need to take more steps to further reduce dioxin exposure. 13 Key Findings of the Reassessment: 95% of General Population Exposure is from animal fats in the commercial food supply Local sources make little contribution to most peoples exposure Environmental levels in meat and dairy production areas major contributor Air deposition onto plants consumed by domestic meat and dairy animals is the principal route for contamination of commercial food supply
Reservoir sources are a significant component of current exposure and may dominate future exposure 8 Modes of Action of Dioxin hsp90 Cl O Cl Cl O Cl hsp90 hsp90 AIP,.. phosphorylation/ dephosphorylation Other Proteins Cl O Cl Cl O Cl RB, ... HIF, Sim,... hsp90
Cl O Cl Cl O Cl DRE BTFs AhR Co-activators Co-repressors Arnt Differentiation and Proliferation chromatin BTFs Ah R Arnt Cl O Cl Cl O Cl Tr
Me ans c h por an t ism TCDD, ... AIP,.. TATA Changes in protein levels (e.g., CYPIA1, IL-1, ...) Altered gene expression mRNA Toxic Effects of Dioxins Multiple effects in multiple tissues of both sexes of multiple species throughout the vertebrate kingdom Lethality Wasting Gonadal/Lymphoid Atrophy Hyperplasia Metaplasia Endocrine disruption Carcinogenicity
Reproductive/ Developmental toxicity Dermal toxicity Immunotoxicity Neurotoxicity Hepatic toxicity Cardiovascular toxicity 16 Key Findings of the Reassessment Adverse non-cancer effects have been observed in animal and humans within 10 times background exposure. It is likely that part of the general population is at, or near, exposure levels where adverse effects can be anticipated. 9 Key Findings of the Reassessment: Risk Characterization
Cancer slope factor is based primarily on published analyses of human studies and is revised upward by a factor of ~6 over the 1985 EPA value. Uncertainty in the value but MOEs for cancer are low. Based on epidemiologic data, probability of cancer risk to the general population may exceed 10-3 (1 in 1,000) from background (dietary) exposure. True risks are likely to be less but we cant say how much less but may approach zero for some individuals (very low exposure/very low susceptibility). 10 Key Findings of the Reassessment: Current US regulatory efforts have addressed most of the known large industrial sources (~80% reduction between 87 and 95; further reductions (>90%) anticipated). Open burning of household wastes is the biggest unaddressed contemporary source identified so far. There remain many uncharacterized sources that could be
significant (agricultural burning, ceramics, forest fires, secondary steel, reservoir sources). 7 ources and Pathways to Human Exposures SOURCES DEPOSITION FOOD SUPPLY TRANSPORT Reentrainment Runoff Erosion 20 Fluxes among dioxin reservoirs Pathways and Sources of Human Exposures Pathways:
Ingestion of soil, meats, dairy products, fish Inhalation of vapors and particulates Dermal contact with soil Sources: Combustion Metal Smelting, Refining, Processing Chemical manufacturing Biological and Photochemical Processes Reservoir sources 22 Dioxin Exposure Trends Environmental levels: Peaked in late 60s/early 70s; declined since based on sediment data Decline also supported by Emissions Inventory which shows significant decrease from 1987 to
1995 (~80%) Human tissue data suggest current levels are about half of 1980 levels (55 to 25 pg TEQDFP/g lipid) Steady state PK modeling of current intake levels project tissue levels of about 11 pg TEQDFP/g lipid. 23 Data for Archived Food Samples Percent difference from current PCDD/F levels Percent difference from current PCB levels 0.07 (0.07) 38 (42) 15 (15)
1884 1897 1909 1921 1932 1946 1955 1964 1974 Year Total CDD/Fs Non-detects = zero 27 Inventory of Sources of Dioxin in the United States- Sept, 2000 draft Municipal Solid Waste Incineration, air Backyard Barrel Burnning, air
Medical Waste Incineration, air Secondary Copper Smelting, air Cement Kilns (haz waste), air Sewage Sludge/land applied, land Residential Wood Burning, air Coal-fired Utilities, air Diesel Trucks, air Secondary Aluminum Smelting, air 2,4-D, land Iron Ore Sintering, air Industrial Wood Burning, air Bleached Pulp and Paper Mills, water Cement Kilns (non-haz waste), air Sewage Sludge Incineration, air EDC/Vinyl chloride, air Oil-fired Utilities, air Crematoria, air Unleaded Gasoline, air Hazardous Waste Incineration, air Lightweight ag kilns, haz waste,air Kraft Black Liquor Boilers, air Petrol Refine Catalyst Reg., air Leaded Gasoline, air Secondary Lead Smelting, air Paper Mill Sludge, land Cigarette Smoke, air EDC/Vinyl chloride, land Primary Copper, air EDC/Vinyl chloride, water Boilers/industrial furnaces
Tire Combustion, air Drum Reclamation, air TOTALS Percent Reduction from 1987 1987 Emissions (g TEQdfWHO98/yr) 1995 Emissions (g TEQdfWHO98/yr) 8877.0 604.0 2590.0 983.0 117.8 76.6 89.6 50.8 27.8 16.3 33.4 32.7 26.4 356.0 13.7 6.1 NA
0% 0% 0% 28 Inventory of Sources of Dioxin in the United States-May, 2000 Municipal Solid Waste Incineration, air Backyard Barrel Burnning, air Medical Waste Incineration, air Secondary Copper Smelting, air Cement Kilns (haz waste), air Sewage Sludge/land applied, land Residential Wood Burning, air Coal-fired Utilities, air Diesel Trucks, air Secondary Aluminum Smelting, air 2,4-D, land Iron Ore Sintering, air Industrial Wood Burning, air Bleached Pulp and Paper Mills, water Cement Kilns (non-haz waste), air Sewage Sludge Incineration, air EDC/Vinyl chloride, air Oil-fired Utilities, air Crematoria, air Unleaded Gasoline, air Hazardous Waste Incineration, air Lightweight ag kilns, haz waste,air
Kraft Black Liquor Boilers, air Petrol Refine Catalyst Reg., air Leaded Gasoline, air Secondary Lead Smelting, air Paper Mill Sludge, land Cigarette Smoke, air EDC/Vinyl chloride, land EDC/Vinyl chloride, water Boilers/industrial furnaces, air Tire Combustion , air Drum Reclamation, air TOTALS Percent Reduction from 1987 1987 Emissions (g TEQdfWHO98/yr) 8877.0 604.0 2590.0 983.0 117.8 76.6 89.6 50.8 27.8 16.3 33.4 32.7
Baseline Baseline Baseline Baseline Baseline I-TEQ (ng/kg waste burned) Results: TEQ Values 10000 1000 100 10 34 Statistical Analysis Results Waste Chlorine Effect Statistically Significant Only at High Cl Levels
At Normal Cl Levels (< 1 % Cl), Other Parameters Dominate Gas-Phase Conditions Important (HCl, T, Cu, burning rate) Majority of PCDD/F Emissions During Smoldering Phase of Burn 35 Activity Level -In 2000, 51.8 Million People Lived in Nonmetropolitan Areas (U.S. DOC, 2000). -Of the Rural Population in the United States, 40 Percent Are Assumed to Burn Their Household Waste in a Barrel (Two Rivers Region Council of Public Officials 1994). -On Average, Each U.S. Citizen Generates 4.5 Pounds of Solid Waste (Excluding Yard Waste) Per Day (or 616 kg/person-yr) (U.S. EPA, 2001). -On Average, in Households that Dispose of Household Waste by Burning, Approximately 63 Percent of Waste Generated Is Burned (I.E., 63 Percent of 616 Kg/person-yr = 388 Kg/person-year) (Two Rivers Region Council of Public Officials 1994). 36 Dioxin Uptake Into Meat And
Dairy 37 Emissions from Known Sources Unlikely to Correlate Proportionally With General Population Exposures. A Majority of the Combustion Sources Are Limited to a Few States The Production of Animal Fats Is Also Concentrated in a Few States Most Major Food Production States Are Are Upwind of Major Emission Production States Open Burning Likely to be a Significant Source of Exposure Reservoir Sources Could Be Significant Source of Exposure 38 Uncontrolled Controlled 39 Summary and Conclusions Dioxin-like Compounds are Highly Potent Carcinogens and exhibit a wide range on non-cancer health effects. Dioxin-like Compounds Background exposure levels result in significant risk.
Exposure is from consumption of animal fats in the commercial food supply. Environmental levels have declined since the '70s but may level off as major industrial emission sources are controlled. Uncontrolled combustion is likely to be the largest unaddressed contemporary sources. Backyard burning of household waste is the best understood and likely the most amenable to reduction of all uncontrolled combustion sources. 40 What Can YOU Do? Share the message Identify other waste disposal methods in your community Reuse (more use means less waste) Recycle (paper, plastics, metallic items) Compost (leaves, yard waste, vegetable wastes) Identify local landfills which accept waste 41 Together we can :
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