Water Pollution (4/7)
Dioxins & Furans
Dioxin is one of the most toxic and environmentally stable tricyclic aromatic compounds of its structural class. Due to its very low water solubility, most of the dioxin occurring in water will adhere to sediments and suspended silts. Similarly, it tends to adhere to soil if released to land, and is not likely to leach to groundwater. Two processes which may be able to remove dioxin from water and soil are evaporation and breakdown by sunlight. Dioxin is generally resistant to microbial breakdown.
Dioxin is released to the environment in emissions from the incineration of municipal refuse and certain chemical wastes, in exhaust from automobiles powered by leaded gasoline, in emissions from wood burning in the presence of chlorine, in accidental fires involving transformers containing PCBs and chlorinated benzenes, and from the improper disposal of certain chlorinated chemical wastes. It has been released to the environment as a low-level impurity in various pesticides.
Dioxin has a very great tendency to accumulate in aquatic life, from algae to fish. Dioxin is formed as a by-product of the manufacture, molding, or burning of organic chemicals and plastics that contain chlorine. It made headlines several years ago at places such as Love Canal, where hundreds of families needed to abandon their homes due to dioxin contamination, and Times Beach, Missouri, a town that was abandoned as a result of dioxin.
Furan is a viscous, colorless liquid that has a pleasant aromatic odor; upon exposure to air it turns dark brown or black. It boils at about 160°C. It is commonly used as a solvent; it is soluble in ethanol and ether and somewhat soluble in water. It is prepared commercially by dehydration of pentose sugars obtained from cornstalks and corncobs, husks of oat and peanut, and other waste products. It is used in the manufacture of pesticides, phenolfurfural resins, and tetrahydrofuran. Tetrahydrofuran is used as a commercial solvent and is converted in starting materials for the preparation of nylon.
EPA's Never-Ending Dioxin Scare
FoxNews.com
Thursday, July 13, 2006
By Steven Milloy
If ever there was an example of what's wrong with the intersection of government and science, the Environmental Protection Agency's 20-year campaign to scare the public about dioxin is certainly a leading candidate.
The EPA slammed into a bureaucratic wall this week when a National Academy of Sciences panel told the agency to take its dioxin report back to the drawing board. But the NAs' rejection of the EPA report was handled with kid gloves -- permitting the agency to save face by allowing the dioxin scare to continue indefinitely. "EPA assessment of dioxin understates uncertainty about health risks and may overstate human cancer risk, " was the headline of the NAs' media release announcing (and summarizing) its review of the EPA's latest dioxin scaremongering.
The NAS said the evidence that dioxin caused cancer in humans was "not strong" and that risk estimates had to be imagined through the use of mathematical models. Despite the acknowledged absence of evidence linking dioxin with cancer in humans, the NAS panel bizarrely agreed that dioxin was "likely to be carcinogenic to humans." It's the sort of 2-plus-2-equals-five conclusion that only connoisseurs of regulatory bureaucracy can fully appreciate.
The EPA issued in 2003 a draft report on dioxin alleging that the substance was 10 times more carcinogenic than the agency previously claimed -- and some dioxin hysterics had already been calling it the "most toxic manmade chemical" for which there was "no safe exposure." these claims were obviously not true since we are all unavoidably exposed to dioxin every day -- it's in our air, food, and water -- from natural and manmade sources without any health effects having been credibly detected despite decades and billions of dollars of scientific research. The only known health effect from dioxin -- a severe acne-like skin condition called chloracne -- is caused by unusually high exposures, such as from an industrial accident or intentional poisoning.
To debunk the dioxin scare, JunkScience.com had a sample of Ben & Jerry's ice cream tested in 1999 for dioxin -- Ben & Jerry's had claimed in one of its "green" marketing campaigns that there was no safe exposure to dioxin. We found that a single serving of the Ben & Jerry's "World's Best Vanilla" contained 200 times the level of dioxin that the EPA said was safe. Our findings -- published in the proceedings of the 20th International Symposium on Halogenated Environmental Organic Pollutants -- jumped up to 2,000 times the EPA's "safe" level using the agency's risk estimates advocated in its 2003 dioxin report.
Despite the commonsense nature of the evidence indicating that dioxin doesn't constitute a public health threat, the EPA has opted to press ahead with the dioxin scare. It's not a surprising choice for the agency given what's at stake. Dioxin has been a high-profile EPA regulatory program for years. The EPA has contributed a great deal to efforts to scare the public about dioxin -- most infamously in the 1980s fiasco at Times Beach, Mo., where the EPA evacuated the entire town and "cleaned up" non-toxic levels of dioxin -- concentrations of dioxin in soil about half the level detected in the Ben & Jerry's ice cream -- for $200 million.
The EPA has also used dioxin hysteria to impose regulations limiting dioxin emissions and to force Superfund clean-ups of dioxin - all costing untold billions of dollars. After so much time and money has gone into promoting and enforcing the dioxin scare, the EPA can't simply give up on bad-mouthing dioxin - much less pronounce the substance safe - lest the agency risk losing even more of its credibility with the public and invite legal challenges to ongoing dioxin regulatory programs.
Not only is it likely that EPA will continue its dioxin persecution, but regulated industries are losing interest in contesting the science of dioxin. Since the late 1980s, industry emissions of dioxin have been reduced by almost 90 percent. As dioxin becomes less of a regulatory cost and concern for industries, they'll lose interest in contesting the science - that, of course, will leave the EPA unchallenged in its campaign against dioxin. And don't count on the National Academy of Sciences to pressure the EPA to stick to sound science on dioxin.
The NAS is a highly politicized organization - opposite sides of an issue, for example, have input concerning the composition of committees reviewing various issues. Including advocates from both sides may sound like a good idea - it ensures that both sides of an issue are heard - but it also often guarantees that NAS reports frequently represent compromises negotiated by committee members rather than conclusions based on the best available science.
The NAS dioxin report reflects this sort of compromise - it threads the dioxin needle without angering either regulated industries or the EPA. For industry, the NAS blocked the EPA from declaring that dioxin is a highly dangerous human health risk, which would help give the agency increased regulatory authority. For the EPA, the NAS endorsed continued agency efforts on dioxin and upheld the agency's public image. This is "political science" at its best. Given the EPA's persistent - and regulated industry's steadily declining - interest in dioxin, there's little doubt that the EPA will win in the end. But I wish the agency luck in regulating the remaining major sources of dioxin in the environment, such as volcanic eruptions and forest fires.
Steven Milloy publishes JunkScience.com and CSRWatch.com. He is a junk science expert, an advocate of free enterprise, and an adjunct scholar at the Competitive Enterprise Institute.
