Dioxin: Unwanted and Unnatural

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Hotline, Winter 2000

The Toxic Release Inventory (TRI) mandated by the 1986 Emergency Planning and Community Right-to-Know Act (EPCRA), has allowed the average citizen to better understand the toxic chemicals released by industry to the environment. So far so good, but a company need only report under certain conditions. If a manufacturing facility (SIC codes 20-39) with ten or more employees uses, imports, processes or manufactures any chemical included on the section 313 list of toxic chemicals in quantities greater than threshold amounts, then it must submit Toxic Chemical Release Inventory forms (Form R) each year. The threshold amounts are 25,000 pounds per year for manufacturing, importing or processing of a listed chemical and 10,000 pounds per year for ancillary use of a listed chemical.

One obvious flaw is that many chemicals pose health risks at extremely small levels, some measured at considerably less than a gram/ year! This year, 2000, for the first time, the EPA through a final rule, established that the threshold for reporting dioxin and a dioxin-like compounds category will be reported if the threshold amount is calculated to be 0.1 gram. The small threshold quantity exemplifies the extreme toxicity of this category of substances and the need for vigilance. Unfortunately, dioxin is not created in some remote chemical process but is a common by-product of many human activities such as combustion where the fuels contain chlorine and carbon. These substances are commonly found in the incineration of medical, solid and hazardous waste and even produced from burning coal alone. Other dioxin production occurs typically during metal smelting, paper bleaching and pesticide production.

Under sections 112(c)(3) and 112(k) of the Clean Air Act as amended in 1990, the Environmental Protection Agency (EPA) is required to identify categories and subcategories of sources of hazardous air pollutants (HAPs) in urban areas that pose a threat to human health (regardless of emissions amounts). Specifically, the EPA must identify sources of at least 30 HAPs that present the greatest threat to urban populations, and assure that sources that account for 90 percent or more of the aggregate emissions are subject to regulation. In addition, a national strategy must be developed to reduce cancer incidence attributable to these pollutants by at least 75 percent.

Dioxins/furans are one category that has been identified and emissions estimates have been completed. Total emissions as estimated by the Environmental Protection Agency, (EPA), in 1994 was 9300 grams TEQ/year, (toxic equivalent) not including emissions from coal. There are no ambient air quality standards for dioxin in the United States.

Dioxin is not a single chemical but a family of chemicals with related properties. There are 75 different forms of dioxin, the most toxic of which is 2,3,7,8 tetrachlorodibenzo-p-dioxin (TCDD). Not all dioxins are highly toxic, only 7 are considered so. There are other chemicals similar in structure to dioxin that have dioxin like behavior. These chemicals are commonly known as furans and PCBs. Of the 135 furans, 10 are considered highly toxic as are 11 of the 209 PCBs.

In order to account for the many forms of dioxins and furans and their varying toxicity levels in a sample, the EPA developed a two step process to determine the total “toxic equivalent” (TEQ) of a sample. The various forms of dioxin and furans are each given a toxicity factor which is based on TCDD having a factor of 1.0. The TEQs are then each multiplied by their concentrations and summed. Where are we likely to be exposed to dioxin? In our food primarily. Dioxin is not absorbed from the soil by plants but it lies on vegetation and soils from deposition of particulates carrying the dioxin molecules, mostly from combustion processes. Here it gets consumed by animals and accumulates especially in fatty tissue. The human body processes dioxin very slowly once it is consumed, creating a buildup of the chemical in fatty tissue-such as the female breast. Dr. Arnold Schecter, an international medical expert on dioxins and an advisor to the World Health Organization stated, “in just six months of breast feeding, a baby in the US will, on average, consume the EPA’s maximum lifetime dose of dioxin,” Thus, nursing infants are particularly likely to receive doses of dioxin.

In 1992, EPA wrote, “In mammals, postnatal functional alterations involving learning behavior and the developing reproductive system appear to be the developmental events most sensitive to perinatal dioxin exposure.” Dioxin was declared a “known human carcinogen” in 1997 by the International Agency for Research on Cancer, an arm of the World Health Organization.

Likewise dioxin arrives in water bodies from soil runoff or air deposition and is taken in by fish and other aquatic animals. Need another reason to be a vegetarian? Foods highest in dioxin are fatty meats, fish, eggs and dairy. It takes between 25 and 100 years for half of a given concentration of dioxin in the soil to degrade. Most degradation takes place by sunlight exposure thus only the very top surface of the soil is affected by photodegradation. The EPA says one cancer in a million persons can be expected to occur with a daily intake of .01 picograms ( a picogram is a trillionth of a gram) of dioxin/kilogram of body weight per day for a lifetime. This is called a “level of concern. ” In 1992, the EPA said the average American is routinely taking in from all sources of food and water, somewhere between 300 and 600 times the “acceptable” amount each day.

Unfortunately, dioxin travels long distances in the atmosphere and is very hard to break down. Schecter, who has been involved with dioxin and PCB studies in Russia, China, Cambodia, the Middle East, and Vietnam, as well as the US, points to the widespread contamination by dioxin. “From penguins in Antarctica to rains that fall in South East Asia to the milk of a nursing mother in Germany, synthetic chemicals have been found.”

The two top sources for air emissions of dioxins according to the EPA in 1998 were from hospital medical waste incineration and municipal waste incineration. The source of the chlorine in the hospitals waste stream is often from polyvinyl chloride (plastic waste). “Greening” Hospitals, a 1998 HCWH,(Health Care Without Harm), report, surveyed fifty major U.S. hospitals and found that only a fifth have programs to reduce purchases of PVC plastic. The average hospital recycles only about a third of readily reusable items.

On September 15, 1997, EPA adopted emission guidelines for existing hospital/medical/infectious waste incinerator(s) (HMIWI). Sections 111 and 129 of the Clean Air Act (CAA) requires States with existing HMIWI subject to the emission guidelines to submit plans to EPA that implement and enforce the emission guidelines.

Allegheny County has adopted the federal plan into Article XXI

  • The regulations controlling medical waste incinerators will limit emissions to 125 nanograms per dry standard cubic meter total dioxins/furans or 55 grains per billion dry standard cubic feet. Facilities will be able to have extensions for construction that could extend their compliance for several years.
  • There is a 10 % opacity limitation (6 minute block average)
  • Compliance except for extensions was February 24, 1999 according to Article XXI. There are many possible reasons for facilities to have allowable extensions.
  • Exemptions include pyrolysis units, cement kilns firing hospital waste, co-fired combustors notifying the Department of an exemption claim, to name a few.

Other sources of dioxin air emissions are municipal, hazardous waste and sewage sludge incinerators, cement kilns, wood burning and coal burning, diesel fuel and gasoline combustion and petroleum refining. A large proportion of dioxin emissions, from many sources, can be traced to a few individual chlorine- related products and processes: PVC plastic, chlorine-based pulp bleaches, pesticides, and chlorinated solvents. But even recognizing all these sources, the EPA noted that there seemed to be more dioxin in the environment than could be accounted for from these sources alone.

Very recently, the EPA reported a new source of dioxin, the backyard barrel burning household trash. An estimated 20 million people in rural areas burn trash in their backyards according to an EPA surveys. According to the report, trash burned in one backyard barrel may release more dioxins and furans than tons of trash burned in a municipal waste incinerator. This is especially true where there has been no recycling which would remove some of the metals, paper, glass and plastics. Many of the above have no emission control requirements for dioxin.

Something not generally recorded by EPA in the literature is the fact that there has been dioxin emissions recorded during coke production. The Netherlands National Institute of Public Health and Environmental Protection (Bremmer et al. 1994) has reported an example of such a scenario in a Dutch Coke Plant. Dioxin emissions of .2 g TEQ/year or 0.23ng TEQ/kg coal consumed were measured in the quenching tower In addition .002g TEQ/kg coal consumed was measured in the flue gases from coal charging. Emissions may likely be controlled by the chlorine content of coal but in the United States, these factors are not extensively researched and there are no regulations. There are many other stages in the coking process where conditions may be appropriate for dioxin formation such as in waste gas, spray dryer and baghouses etc. Activated carbon injection in combination with particulate control is recommended by EPA for municipal and hazardous waste facilities to reduce dioxin emissions. Allegheny County has the largest coking facility in the US at USX Clairton and additional batteries at Shenango Coke that run day and night in very urban areas, yet there are no requirements for control at these facilities.

Dioxin is such a potent toxic substance, already so pervasive, that all sources need to be put into the cumulative picture. Communities should be made aware of dioxin emissions from any source and where possible pollution controls should be mandated by the controlling environmental agencies.

Things you can do:

  • Write your legislators insisting on firm controls, monitoring and standards for this extremely toxic substance
  • Buy only unbleached or oxygen bleached paper
  • Urge your local hospitals to purchase non chlorine containing plastics and recycle chlorine based chemicals into landfills
  • Include production of dioxin from coal combustion sources such as utilities and coke ovens in any inventory
  • Discourage incineration of any type that has as fuel a combination of materials that could produces dioxin
  • Don’t burn personal trash or garbage

by Suzanne Seppi, GASP Executive Director