Dioxins, combustion and cancer

Dioxins are often hitting the headlines: “Iraq littered with high levels of nuclear and dioxin contamination, study finds”, “Up to 100,000 Irish pigs to be culled because of dioxin scare” and “Supermarkets on dioxin alert over contaminated egg products“. However, do dioxins really deserve their bad name? And what are they really?

What are dioxins?

“Dioxins” can be defined in two different ways. They can be either be defined as a compound with a certain chemical structure, namely a heterocyclic 6-membered ring.

The term “dioxines” can also be more loosely used to describe a class of chemicals that share certain chemical- as well as biological properties (don’t get scared of the chemical terminology!). To this class belong polychlorinated dibenzo-para-dioxins (PCDDs) and polychlorinated dibenzofurans (PCDFs).

Not all are acutely toxic. However, there are some nasty group members and the nastiest of the them all is probably 2,3,7,8-tetrachlorodibenzo-para-dioxin, for laymen also called TCDD. TCDD was one of the ingredients in Agent Orange, which was used during the Vietnam War.

Dioxin. By Lukáš Mižoch (Own work) [Public domain], via Wikimedia Commons

(Image credit: Lukáš Mižoch)

Dioxins are formed during combustion (burning) such as burning of waste (particularly when old methods are used), forest fires, and paper factories as well as during many industrial burning processes. There are natural sources of dioxins and even though they are natural, they are not healthy! I know that I am repeating myself: Do not fall for the “but it is natural”-argument. Nature can be a backstabbing conniving old crone.

Stacks of 55 gallon drums of Agent Orange used in the Vietnam War. By U.S. Army [Public domain], via Wikimedia Commons

Stacks of 55 gallon drums of Agent Orange used in the Vietnam War (image credit: U.S. Army)

Effects of dioxins

The problem with dioxins is that they break down extremely slowly and can have very nasty effects on ecosystems and human health. The nastiness of the response has to do with how much you have been exposed to, for how long and when in your development this exposure took place. Children are more sensitive to these compounds than adults for example.

Because dioxins break down so slowly, they often accumulate in sediments and soils, where they are taken up by the organisms living there, to be further transported up the food web to larger and larger animals. The ecosystems can really suffer from such contaminators.

Dioxins can be stored in the liver or brain and other fatty tissues, such as your butt cheeks. Dioxin concentrations in fat tissue increase up the food web. Large animals eat many small ones and accumulate the compounds. This process is called bio-accumulation. The half-life of most dioxins is 7-11 years, meaning that it takes 7-11 years for the concentrations to be reduced by 50 %.

Bioaccumulation: many small organisms are eaten by the large ones, resulting in higher dioxin concentrations in the meat-eating ones. By Martin-rnr (Own work) [GFDL (http://www.gnu.org/copyleft/fdl.html) or CC BY-SA 3.0 (http://creativecommons.org/licenses/by-sa/3.0)], via Wikimedia Commons

Bio-accumulation: many small organisms are eaten by the large ones, resulting in higher dioxin concentrations in the meat-eating ones (image credit: Martin-rnr)

Some people who have become exposed to very high levels of dioxins may develop so called chlor acne, which looks very similar to normal acne. Dioxins can damage the immune system and disturb your hormonal balance. Due to this, dioxins have been linked to reproductive illnesses such as endometriosis. Dioxins are also highly carcinogen (cancer causing) and have also been shown to cause developmental problems. Therefore, it is not good for pregnant women to be exposed to a lot of dioxins.

Detox – are you serious!?!

Here I would like to make a small slightly unrelated remark on some of the advice given by a variety of quackery crackpots: detox. Most of the detox methods I have read about are so funny from a biological perspective, that I think that most of the quacks either must have missed basic biology in school, or they are extremely skilled entrepreneurs counting on that enough people have indeed missed basic biology in school for their products to be a financial success.

Some of these detox-methods are based on fasting. Fasting will make you lose a lot of fat fast, but it also means that you will release a large amount of fat soluble toxins from your fat stores very fast. Your poor body, and notably your liver, will have to deal with these toxins. There can be other benefits from fasting, but to call it detox is just ludicrous. It should rather be called tox.

Where do you get your dioxins from?

Meat and dairy. A quick and fast answer. No moral finger-pointing, just a plain and simple scientific fact. A study published by the U.S. Environmental Protection Agency (EPA) showed that North Americans received 93 % of their total dioxins from meat and dairy products. Trimming fat off your meat will help reduce your intake of dioxins.

Dioxin formation and destruction through combustion

Dioxins can be formed during many combustion processes such as backyard burning of trash or even burning of paper. The Shibamoto-paper below states that dioxins are formed at temperatures above 450 °C, but not above 850 °C.

Due to better processes, the dioxin production in U.S. municipal waste incinerators was reduced by 86 % between 1986 and 1995.

Interesting is that removing chloride in PVC (plastic) apparently does not affect the dioxin formation since chloride is not the limiting compound of this reaction. Chloride is too abundant naturally and only a tiny fraction of the chloride present in the waste is actually ending up in the dioxins and furans. As an example: air from an incinerator contains 20 times more chloride than needed to produce the standard amounts of dioxins/furans. Therefore our effort should not be focused on targeting reduction of chloride in plastic.

To reduce the production of dioxins, the so called “3-T Rule” has been set in place:

  1. Combustion Temperature needs to be high enough
  2. Combustion Time needs to be accurate (apparently 2 s in a modern incinerator)
  3. Combustion Turbulence needs to be high (meaning that the heat needs to be evenly distributed)

Also, formation of dioxins after the combustion process also needs to be prevented:

  1. So called fast-quench: cool the produced gas quickly down to about 250 °C to prevent the gas being in the “dioxin-formation zone” for a long period of time.
  2. Avoid presence of copper since it facilitates the formation of dioxins. This would be yet another reason for not throwing electrical waste in your household-trash.

Waste incinerator. John Haynes [CC BY-SA 2.0 (http://creativecommons.org/licenses/by-sa/2.0)], via Wikimedia Commons

Waste incinerator (image credit: John Haynes)

It is possible to deal with dioxin contaminated material by incinerating it, even PCB-based industrial waste oils can be managed by burning them at temperatures above 850-1000 °C (depending on the amount of material combusted).

Even though I just mentioned that reducing chloride from for example PVC does not affect dioxin production, there are one million other reasons for us to ditch our plastic addiction and dependence, but that I will rant about in another post.

Viktor Yuschenko with chlor acne after his dioxin poisoning. By Muumi (Own work) [GFDL (http://www.gnu.org/copyleft/fdl.html) or CC-BY-SA-3.0 (http://creativecommons.org/licenses/by-sa/3.0/)], via Wikimedia Commons

Viktor Yuschenko with chlor acne following his dioxin poisoning (image credit: Muumi)

Finally, I would like to share the most peculiar thing I found about dioxins and that is the poisoning of the Ukrainian opposition leader Viktor Yushchenko. This was very strange since there are thousands of other compounds better suited for this purpose. This was the first time (recorded) that someone has been intentionally poisoned with dioxins in a direct manner. However, do not forget all the people who have died prematurely due to indirect dioxin exposure.  Please, skip your backyard burning of trash. There are places where you can legally deposit it.

Science Safely!

Dr. Anna of The Imaginarium

...enjoys meat, but not very often.

…enjoys meat, but not very often.

U.S. EPA. Update to An Inventory of Sources and Environmental Releases of Dioxin-Like Compounds in the United States for the Years 1987, 1995, and 2000 (2013, External Review Draft). U.S. Environmental Protection Agency, Washington, DC, EPA/600/R-11/005A, 2013.

EPA Dioxin Reassessment Summary 4/94 – Vol. 1, p. 37. (Figure II-5. Background TEQ exposures for North America by pathway)

WHO Fact sheet N°225: Dioxins and their effects on human health. Updated June 2014

Dioxin formation from waste incineration. Shibamoto T, Yasuhara A, Katami T. Rev Environ Contam Toxicol. 2007; 190:1-41.

US Environmental Protection Agency Inventory of Sources of Dioxin-Like Compounds in the United States-1987 and 1995″ http://cfpub.epa.gov/ncea/cfm/dioxindb.cfm?ActType=default


Posted in Biology, Chemistry, Environment and tagged , , , .

Dr. Anna

Dr. Anna Zakrisson is a multifaceted biologist with degrees from world-renowned institutions such as Cambridge University, U.K. and the Max-Planck Institute in Germany. She has published a range of high-ranking scientific papers and crossed oceans on research vessels. She runs The Imaginarium science blog and YouTube channel and speaks English, German and Swedish fluently.

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