Dioxin, Furans, & PCB Emission for Residential Trash Burning
MOS 5425 Advanced Toxicology
Dr. Brooks McPhail
October 7, 2014

Dioxin, Furans, & PCB Emission for Residential Trash Burning In the United States, the Environmental Protection Agency (EPA) estimated in 2006 Americans generated 300 million tons, 12.5 percent burned in incinerators. Countless of the hundreds of thousands of tons are burned in residential backyard burn barrels in rural areas, are never accounted for. To the residential homeowner burning trash has been for centuries the means of disposing refuse in areas that do not have organized garbage collection. As the modern industrial chemical production continues to increase, making products that make everyday life in the modern world more accessible, burning that waste stream at low temperatures products highly toxic compounds releasing not only in the air via smoke but also in ash runoff, and smoke fume condensation on possible food sources. Countless toxicological studies have been conducted on dioxins, furans and polychlorinated biphenyl (PCBs). That information will be leveraged here to compliment the toxicity and pollutant effects of these chemicals, yet the emphasis is not political, environmental, nor humanitarian. It is about highlighting the non-industrial emissions, choices in some cases, and for others the realization, that these toxic chemicals are a result of disposing product we receive from the modern industrialized world. Dioxins, furans and PCBs are unwanted by-products of burning of household trash, oil heating, burning wood stoves, and diesel exhaust smoke, and certain industrial processes. The EPA, now considers non-industrial burning of household wastes in burn barrels to be the largest emissions source of dioxins, furans and PCBs (Dow Chemical, 2014). Dioxins, furans, and PCBs, are all considered toxic to humans. Exposure can be through the air, water, and soil. Those that burn residential waste are unaware of the harmful effects the smoke emissions can be to health, but also rain run-off from the burn site into ground water sources, for springs, and drinking water wells, and even the puddle of water the family pet drink from occasionally. Dioxins, furans and PCB saturated smoke fumes can precipitate from the fume on backyard gardens, orchards, children’s toys and play sets -smoke emissions from burn barrels can be carries short and far distances by winds and water droplets in clouds (Environmental Protection Agency, 2014).
Typically dioxins, furans and PCBs (though PCBs were commercially produce for 80 years) do not exist in municipal waste before they are burned, but are a product of the burning process. Acute exposure to these compounds can cause skin rash, nausea, and headache from inhalation of the smoke product, chronic exposure can lead to heart disease, respiratory ailments, emphysema, and disorders of the endocrine, hepatic, nephrotic, reproductive, and able to be passed to infants through female nursing. The reason these three compounds are lumped together, is due to structural similarity, and the multitudes of congeners to each structure (Rodan, 1997).
Dioxins, furans, and PCBs are chemically similar in structure, considered highly toxicity, and considered environmental pollutants, and persistent organic pollutants (Kacew & Lee, 2013). Reference the Figure Page, for the similarities figures 1, 2, 3- in chemical structure. Toxicologically to track these compounds (to include associated congeners) as a smoke emission (in this case a residential burning barrel), the environmental fate and pathways to human exposure would follow the smoke source, including entrainment from previous burning, to air contamination from the smoke fumes. This air also serves as a transport medium for deposition from fume precipitation contact on food sources, and water droplet encapsulation in atmospheric clouds, then deposition back to the ground from water precipitation, then into the food supply (Rodan, 1997).
In the context of a public health, it is east to identify the hazards from dioxins, furans and PCBs, just on the sheer volume of information present. In this specific case, the response would be a quantifying risk assessment of from the burning of trash in burn barrels to both the homeowner and the public. In this case, the there is no risk from the trash, per se; the risk arises from burning trash. To conduct a human health hazard risk assessment there are five components: planning, hazard identification, a dose-response assessment, exposure assessment and risk characterization (Environmental Protection Agency, 2014). As an example, a planning draft of the risk assessment would look similar to:
Planning:
Who/What /Where is at risk * The individual(s) exposed to latent smoke * The general population downwind of the smoke * All individuals, gender, ages and the unborn child are at risk * Population subgroups that are at increased risk are those that do not have trash pick-up or access to industrial, EPA licensed incinerators.

What is the environmental hazard of concern * Exposure from trash smoke fumes containing dioxins, furans and * Ash pile and fly ash dusts * Rain run-off from the ash heap * Soil contamination * Exposure to locally grown food sources downwind of the smoke

The Hazard occurs from a point source * Trash burned

How does the exposure occur * Acute * Air (Inhalation * Surface water (Ingestion, Absorption) * Soil (Absorption) * Ash handling (inhalation, absorption are primary) * Chronic * Groundwater (Ingestion) * Food (Ingestion)

What does the body do with the environmental hazard and how this influenced by factors such as age, race, sex, and genetics. * Absorption – the body does take the toxins up into the system * All three compounds affect the respiratory system, hepatic, nephrotic, and nervous system * Absorbed in mammary glands and passed to nursing infants

What are the health effects * Health effects include cancer, heart disease, liver disease and nerve disease.

The EPA has provided a simple flow chart to diagram the last four steps in the process, in Figure 4.
From a toxicology assessment, the dose-response assessment is the basis for determining the toxicity of all three. Multiple reference sources agree, that all the compounds bio accumulate in the food chain of human consumption. For Dioxins the LD50 dose for Guinea Pigs range for the toxic congeners 0.115 mg/kg, LD50 rabbit 0.107mg/kg, and the toxicity for chloro, bromo, iodo (halogens) dibenzofuran congeners showed a much higher toxicity levels, LD50 rat/monkeys/guinea pigs 5µg/kg (Patnaik, 1999). A draft estimate as late as 2006 showed that the average daily intake of dioxins, furans, and PCBs as total equivalent of toxic congeners combined as approximately 6pg/day, with 96 percent of the intake from food ingestion. This is an indicator that none of the three compounds undergo little degradation as it works through the food chain, bioaccumulating. Concomitantly, all three compounds and a predominate amount of the congers are also noted to be carcinogenic, and teratogenic for the molecular weight congers 253 – 459 MW (Patnaik, 1999). In conclusion, residential burning of trash in barrels has proven to a more serious threat as first though, because of the low temperature in the process of burning. EPA licensed incinerators have specialized processes that dramatically increase the temperature at which refuse is burned. In fact, the process is akin to pyrolysis that incineration. The heat of the incinerator is so high it decomposes dioxins, furans and PCBs, into low molecular weight gases. The EPA has left increased control of trash burning to the states. The fact that most products used contain some type of halides in the processing, from paper milk carton, to plastic lining inside metal canned products, combine with carbon in the combustion to form dioxins, furans and PCBs.

FIGURES

Figure 1
2,3,7,8-TETRACHLORODIBENZO-P-DIOXIN (TCDD) or Dioxin (The National Center for Biotechnology Information - National Library of Medicine, 2014)
75 Congeners/ 7 Considered Highly Toxic

Figure 2
2,4,5,2',4',5'-hexachlorobiphenyl, Araclor 153 (The National Center for Biotechnology Information - National Library of Medicine, 2014)
209 congeners/13 Considered “Dioxin-Like” (Rodan, 1997)

Figure 3
1,2,3,4,6,7,8,9-Octachlorodibenzofuran, Dibenzofuran (The National Center for Biotechnology Information - National Library of Medicine, 2014)
135 Congeners/ 10 Considered Highly Toxic

Figure 4 (Environmental Protection Agency, 2014)

References
Dow Chemical. (2014, October 6). How Dioxins and Furans are Formed. Retrieved from Dow: http://www.dow.com/sustainability/debates/dioxin/definitions/how.htm
Environmental Protection Agency. (2014, October 6). Human Risk Assesment. Retrieved from US Environmental Protection Agency: http://epa.gov/riskassessment/health-risk.htm
Environmental Protection Agency. (2014, October 6). Wastes-non-hazardous waste-munipcipal solid waste. Retrieved from Environmental protection agency: http://www.epa.gov/solidwaste/nonhaz/municipal/backyard/index.htm
Kacew, S., & Lee, B.-M. (2013). Lu's bsic toxicology: fundamentals, target organs, and risk assessment. London: CRC Press.
Kulpinski, D. (2014, April 14). Human footprint: where does all that stuff go? Retrieved from National Geographic: http://channel.nationalgeographic.com/channel/human-footprint/trash-talk.html
Patnaik, P. (1999). Hazardous properties of chemical substances. New York: John Wiley and Sons.
Rodan, B. P. (1997, November 25-28). Polychlorinated dioxins and furans:Sources, emmissions and levels. Washington, District of Columbia, USA.
The National Center for Biotechnology Information - National Library of Medicine. (2014, October 6). The National Center for Biotechnology Information. Retrieved from PubChem: https://pubchem.ncbi.nlm.nih.gov/summary/summary.cgi?cid=15625&loc=ec_rcs#itabs-3d