Dioxin
DIOXIN POLLUTION PREVENTION AND PVC PLASTIC IN
MUNICIPAL SOLID WASTE: PRECAUTIONARY STATE POLICY
Michael E. Belliveau
Environmental Health Strategy Center, P.O. Box 2217, Bangor, Maine 04402, USA
Introduction
The disposal of municipal solid waste (MSW) generates polychlorinated dibenzo-p-dioxins and
polychlorinated dibenzofurans (referred to together as “dioxin”) through open burning, waste
incineration and landfill fires1,2. Backyard burning of household trash is a significant source of
dioxin3. In the U.S., about 100 municipal waste combustors incinerate about 20% of MSW after
recycling4, compared to 70% in Maine. Dioxin air emissions from MSW incineration have
declined due to facility closures, operating improvements and added pollution controls5. Dioxin
air emissions remain significant and incinerator ash adds very large amounts of dioxin to the land6.
40% to 70% of the chlorine input to MSW incinerators is from polyvinyl chloride (PVC), a widely
used plastic7. Yet PVC accounts for only 0.6% of the total mass of MSW4. Several variables
affect dioxin formation during incineration including chlorine precursors, metal catalysts, oxygen
content, combustion temperature, residence time, quenching conditions and pollution controls5.
Many studies have correlated chlorine input and dioxin formation during combustion8,9,10,11,12,13. A PVC industry-funded study found no correlation between chlorine input and dioxin air emissions
in MSW combustors14. Others have also discounted the importance of chlorine input to dioxin
formation15. These negative findings have been criticized for flawed analysis16. The relationship
between chlorine input and dioxin formation in waste incineration remains complex and uncertain.
The precautionary principle holds that if an activity raises threats of harm to human health or the
environment, then preventive actions should be taken even if some cause and effect relationships
are not fully established scientifically17. While risk assessment justifies a halt to open burning, a
precautionary approach supports dioxin pollution prevention by reducing the incineration of PVC.
Materials and Methods
In 1997, the Maine Department of Conservation surveyed 545 town fire wardens and state forest
fire rangers about backyard trash burning. The Maine Department of Environmental Protection
(DEP) used these survey results, EPA emission factors for burn barrels3 and air dispersion
modeling (ISCST3) to characterize exposure, risk and mass emissions of dioxin. In 1999, a
medical waste disposal crisis spurred the Maine Hospital Association and Maine DEP to develop a
plan for in-state management of biomedical waste and reductions in waste volume and toxicity18.
In 2000, the Maine DEP began drafting a plan for the statewide collection of household hazardous
waste19 and in 2001 the Maine Legislature began policymaking on PVC to address dioxin issues.
Results and Discussion
The 1997 backyard burning survey identified 8,510 permitted burn barrels in Maine or about one
barrel for every 144 people. An inverse relationship was found between population (by county or
Organohalogen Compounds, Volumes 60-65, Dioxin 2003 Boston, MA
by town) and the number of burn barrels per 1,000 residents, showing that backyard incineration is
a rural phenomenon. When surveyed, local fire wardens offered three broad categories of opinion
as to why rural people burned their trash in backyard barrels: economic incentives (e.g. avoiding
pay-as-you-throw disposal fees), cultural habits and the inconvenience of proper disposal2.
Environmental releases of dioxin in air emissions and ash from backyard burn barrels in Maine in
1997 are reported in Tables 1 and 2, based on 21 tons per day of waste burned in barrels2. Burn
barrels were found to be a significant source of dioxin air emissions (7 - 23 grams TEQ/year). The
high dioxin content of burn barrel ash also raises environmental health concerns. Air dispersion
modeling showed that fifteen minutes of open burning resulted in dioxin impacts two times the
health based guideline for subchronic (24-hour) exposure at a downwind distance of 500 meters2.
The 2000 Maine dioxin inventory (Table 3) revises the estimate of dioxin air emissions from burn
barrels to 4.1 grams TEQ (26% of air emissions). This exceeds the 2.0 grams TEQ dioxin air
emissions from Maine’s four municipal waste combustors, which burn about 600,000 tons of
MSW each year20. Dioxin releases to land from disposal of MSW incinerator ash account for 34.1
grams TEQ or 60% of all dioxin released to air, water and land, far more than from any source.
Table 3 also shows that PVC plastic is the major chlorine donor for dioxin sources that account for
79% of quantified dioxin releases to air, water and land. PVC is also the major chlorine donor for
dioxin releases from car and building fires, open burning at construction sites and landfill fires.
About 75% of PVC is used for building and construction21. PVC mixed with wood recovered
from construction and demolition debris may form dioxin when burned at biomass power plants.
In 2001, Maine’s 39 hospitals pledged to steadily reduce the use and disposal of PVC plastic so as
to prevent dioxin formation from both medical and solid waste incineration. Disposable PVC
medical products such as IV bags, tubing and gloves account for 10% -15% of medical waste22.
Table 4 lists the steps being taken by to reduce PVC use. Maine hospitals have made modest
progress in reducing PVC (Table 5), reflecting the complexity of the task and the need to move the
market23. The Southern Maine Medical Center has already switched to PVC-free IV bags.
In 2001, the State identified PVC as a problem waste that should be included in a statewide
household hazardous waste collection program19. Legislation was proposed (LD 1543) to define
PVC plastic as a dioxin-forming product, fund an education program to discourage open burning
of MSW and encourage the diversion of PVC waste away from incineration. The bill was strongly
opposed by the chemical industry and was substantially amended before being signed into law to:
1. Ban all open burning of MSW in Maine (except for clean wood waste)
2. Fund a one-time educational program to discourage open burning and promote PVC alternatives
3. Establish a state policy to reduce the total release of dioxin to the environment with the goal of
its continued minimization and, where feasible, ultimate elimination
4. Require a study by the State Planning Office (SPO) to assess the feasibility of diverting PVC in
MSW away from incineration, which concluded in 2003 that: “the majority … supported
identifying polyvinyl chloride plastics as a material of concern in the state’s efforts to reduce the
formation of dioxins and their release into the environment” and “there was substantial support for
efforts that would result in the diversion of polyvinyl chloride plastic away from incineration”24.
Further actions are needed to prevent dioxin releases to air, water and land from MSW disposal.
Organohalogen Compounds, Volumes 60-65, Dioxin 2003 Boston, MA
Given the factors that motivate rural Americans to use backyard burn barrels, statutory bans on
open burning are unlikely to be effective alone. The highly successful anti-tobacco industry
public health campaign to reduce smoking could serve as a model. An industry-funded but
publicly-controlled public education campaign against open burning should target the chemical
industry as responsible for dioxin-forming products such as PVC in the waste stream. Like
household hazardous waste, PVC should be separately collection and diverted away from
incineration. Expanded labeling of PVC products would facilitate education, identification and
waste segregation. Disposable PVC packaging, e.g. consumer bottles and ‘blister packs’, should
be phased out. We should exercise precaution by working to eliminate PVC plastic from MSW.
Table 1: Estimated Dioxin Releases to Air from Backyard Burn Barrels in Maine
Pollutants
Scenario
Emission Rate
EPA Study3 (mass
emitted per kg waste)
Estimated Daily
Emissions per
Household (g/day)
Estimated Total
Annual Emissions
(g/year)
Dioxins TEQ Worst-Case 0.005 mg/kg 0.000007 23
Average 0.002 mg/kg 0.000006 7
Calculations based on: Maine waste production = 1.2 kg/capita/day; average household size = 2.5 people; number of burn
barrels in Maine = 8,510; Maine average recycling rate = 25%; combustion rate = 68.1% (worse-case scenario) or 57.9%
(average scenario) of original mass burned. Tables 1 & 2 adapted from Maine Department of Environmental Protection2.
Table 2: Estimated Dioxin Releases to Land (as Ash) from Backyard Burn Barrels in Maine
Scenario Dioxin Concentration in Ash
(EPA Study3) ng/kg (ppt) TEQ
Ash Produced
(kg/year)
Total Dioxin Releases to Land as
Ash (grams/year)
Worst-Case 2,586 3,732,039 10
Average 1,611 2,942,300 5
Table 3. Maine Dioxin Inventory 2000: Dioxin Releases to Land, Air and Water
Dioxin Source
Dioxin
Release to:
Total Dioxin
(grams TEQ)
Is PVC a Major
Chlorine Donor?
Municipal Solid Waste Incinerator Ash Land 34.1 YES
Backyard Burn Barrels Air 4.0 YES
Residential Fuel Burning (wood & oil) Air 3.4
Commercial / Industrial Fuel Burning Air 3.1
Backyard Burn Barrel Ash Land 2.9 a YES
Pulp & Paper Mills – Kraft Bleach Discharge Water 2.3
Municipal Solid Waste Incinerators Air 2.0 YES
Medical Waste Incinerators Air 1.7 YES
Utility Boilers (biomass/wood and oil-fired) Air 1.1 some b
Pulp & Paper Mills - Sludge & Ash Land 1.0
Non Point Sources, including On Road Vehicles Air / Water 0.6
Sewage Sludge Land 0.2
Miscellaneous Industrial Sources Air 0.1
Biomass/Wood-Fired Power Plant Ash Land < 0.1 some b
Automobile & Building Fires Air / Land nd YES
Industrial Sludge & Kiln Dust Land nd
Landfill Fires Air / Land nd YES
Open Burning (construction sites, etc.) Air / Land nd YES
TOTAL > 56.6
Adapted from Maine DEP6. nd = no data; a = extrapolated from 1997 study; b = from PVC-contaminated scrap wood
Organohalogen Compounds, Volumes 60-65, Dioxin 2003 Boston, MA
Table 4: Hospital PVC Reduction Steps18 Table 5: Maine Hospitals’ Progress – Jan 200322
1. Establish a written PVC reduction policy
2. Assess current use of PVC products.
3. Reduce PVC use in disposable products
4. Replace PVC use in durable products
5. Ask GPOs to evaluate of PVC alternatives
6. Renegotiate GPO contracts on PVC prod.
7. Report annually on progress achieved
GPO = Group purchasing organization
Activity Completed
% Completed
(# of hospitals)
PVC Reduction
Product inventory 21 % (8)
Patient safety review * 10 % (4)
Minimize incineration 8 % (3)
Product phase-out not yet quantified
* based on patient exposure to toxic PVC additive DEHP
Acknowledgements
Funding for this work has been provided by John Merck Fund, Bingham Program & Beldon Fund.
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Organohalogen Compounds, Volumes 60-65, Dioxin 2003 Boston, MA