DIOXINS – A Serious Health Threat with Very Little Awareness!

Key facts

• Dioxins are a group of chemically related compounds that are persistent environmental pollutants (KÇK).
• Dioxins occur widely in the environment worldwide and accumulate in the food chain, particularly in animal fatty tissue.
• More than 90% of human exposure comes through food, mainly meat and dairy products, fish and shellfish. Many national authorities have programs to monitor the food supply.
• Dioxins are highly toxic and may cause reproductive and developmental problems, damage the immune system, interfere with hormones and cause cancer.
• Because dioxins are ubiquitous, everyone has background exposure not expected to affect human health. Nevertheless, their high toxic potential requires efforts to reduce current background exposure.
• Preventing or reducing human exposure is best achieved through source-directed measures: strict control of industrial processes to reduce dioxin formation.

What is dioxin?

Dioxins are environmental pollutants, a group of hazardous chemicals known as persistent organic pollutants (KÇK), also called the dirty dozen . Their high toxic potential is concerning. Experiments have shown effects on a range of organs and systems.

After entering the body, dioxins mainly enter fatty tissue and remain stored for a long time. Their bodily half-life is estimated at 7 to 11 years. In the environment, they tend to accumulate in the food chain. The higher an animal is in the food chain, the higher the dioxin concentration.

The chemical name of dioxin: 2,3,7,8-tetrachlorodibenzo para dioxin (TCDD). The name "dioxins" commonly refers to the structurally and chemically related family of polychlorinated dibenzo para dioxins (PCDDs) and polychlorinated dibenzofurans (PCDFs) . Certain dioxin-like polychlorinated biphenyls (PCBs) with similar toxic properties are also included under "dioxins." Of 419 identified types of dioxin-related compounds, only 30 are considered significantly toxic, with TCDD the most toxic.

Sources of Dioxin Contamination

Dioxins are mainly by-products of industrial processes, but may also arise from events such as volcanic eruptions and forest fires, natural processes. They are unwanted by-products of many manufacturing processes, including smelting, chlorine bleaching of paper pulp and production of certain herbicides and pesticides. In terms of environmental dioxin releases, uncontrolled waste incineration facilities (solid and hospital waste) are often the worst offenders because of complete combustion. Technology enabling controlled waste incineration with low dioxin emissions is available.

Although dioxin formation is local, its environmental distribution is global.

Dioxins occur worldwide in the environment. The highest levels are found in certain soils, sediments and foods, particularly dairy products, meat, fish and shellfish (even breast milk). Very low levels occur in plants, water and air.

Dioxin-like polychlorinated biphenyl (PCB)-based waste industrial oils contain high amounts of polychlorinated dibenzofurans (PCDFs) and are widespread globally. Long-term storage and improper disposal can release dioxins into the environment and contaminate human food and animal feed. PCB-based waste cannot be disposed of easily without contaminating the environment and human populations. It must be handled as hazardous waste and is best destroyed by high-temperature incineration in specialized facilities.

Dioxin Contamination Incidents

Many countries monitor food for dioxins. This has enabled early detection and generally prevented effects on a larger scale. Contamination often arises through contaminated animal feed: for example, increased dioxin levels in milk or feed have been traced to clay, fat or citrus pulp pellets used in feed production.

Dioxin Contamination Incidents in History

• In late 2008, Irish pork samples were found to contain dioxins up to 200 times the accepted safe limit, leading to destruction of tons of pork and pork products. This was among the largest incidents of chemical food contamination. Irish risk assessments indicated no public health concern. This process is now monitored much more closely in Ireland.
• In 1999, poultry and eggs from Belgium were found to contain high dioxin levels. Dioxin-contaminated animal foods (poultry, eggs, pork) were subsequently identified in other countries. The cause was animal feed contaminated by illegally discarded PCB-based waste industrial oil.
• In 1976, Italy’s town of Seveso was the site of an accident at a chemical factory , releasing a large quantity of dioxins. A cloud of toxic chemicals, including TCDD, entered the air and eventually contaminated an area inhabited by 37.000 people, covering 15 square kilometers.
  Extensive studies in the affected population continue to determine long-term human health effects.
• TCDD was also used in large quantities during the Vietnam War by the US military as a defoliant, in Agent Orange herbicide. Agent Orange was a herbicide and defoliant used by the US military particularly in the Vietnam War. It was first used there by the American military on 7 February 1967, and nearly 20 million gallons were sprayed during the war. Health effects on local people exposed during and after the Vietnam War have been extensively studied, including muscle and bone disorders and congenital abnormalities. Links to certain cancers and diabetes remain under investigation.

"Agent Orange" was not actually a colored agricultural chemical; orange markings appeared on the barrels carrying it.

Although all countries may be affected, most contamination cases have been reported in industrialized countries where adequate food monitoring occurs, with greater hazard awareness and better regulatory controls enabling detection of dioxin problems. 

Several cases of intentional human poisoning have also been reported. The most notable involved Ukrainian President Viktor Yushchenko in 2004, whose face was disfigured by acute dioxin poisoning.

Viktor Yushchenko describes this poisoning in a National Geographic documentary as follows:

"I was invited to a meeting at the secret service. I attended although I did not want to. After approximately 1-2 hours, as I was leaving, they wanted to serve food. A specially prepared portion arrived, and I took some. After the meal, my face swelled to twice its size and turned pink-blue. We sent samples to 4 different countries for testing. Dioxin poisoning was detected. Only the Russian laboratory did not respond. The day after the poisoning, all officials attending that meeting fled to Russia."

Effects of Dioxins on Human Health

Human exposure to high levels of dioxins over the short term may cause skin lesions such as patchy darkening and altered liver function. Long-term exposure impairs the immune system, developing nervous system, endocrine system and reproductive functions.

Chronic animal exposure has resulted in various cancers. TCDD was evaluated by the World Health Organization’s (DSÖ) International Agency for Research on Cancer (IARC) in 1997 and 2012. Based on animal and human epidemiological data, IARC classified TCDD as a "known human carcinogen" (Group 1 carcinogen). However, TCDD is not genotoxic (does not affect genetics), but increases cancer risk after a certain exposure.

Because dioxins are ubiquitous, everyone has background exposure and a certain level in their body, creating a body burden. Current normal environmental exposure is not expected to affect average human health. Nevertheless, the high toxic potential of this compound class requires efforts to reduce existing background exposure.

Vulnerable Groups

The developing fetus is most sensitive to dioxin exposure. Newborns with rapidly developing organ systems may be more vulnerable to some effects. Some people or groups may have higher exposure through diet (high fish consumption in certain regions), living near hazardous waste sites, or occupations such as work in incinerators and the pulp and paper industry.

Prevention and Control of Dioxin Exposure

Proper incineration of contaminated material is the best way to prevent and control dioxin exposure. PCB-based waste oils can also be destroyed with appropriate technology. Incineration requires high temperatures above 850 ° C (degrees Celsius). Destroying large quantities of contaminated material requires higher temperatures—1000 ° C or more.

Preventing or reducing human exposure is best accomplished through source-directed measures, meaning strict control of industrial processes to minimize dioxin formation. This is the responsibility of national governments.

More than 90% of human dioxin exposure comes from the food supply, mainly meat and dairy products, fish and shellfish. Protecting the food supply is therefore crucial. Alongside source-directed emission reduction, secondary contamination of food must be avoided. Good controls and practices during primary production, processing, distribution and sale are essential for safe food production.

As the examples above indicate, contaminated animal feed is often the root cause of food contamination.

Food and feed monitoring systems must ensure tolerance levels are not exceeded. Feed and food producers are responsible for safe raw materials and production processes, while national governments must monitor food supply safety and act to protect public health. Countries should have emergency plans to identify, hold and dispose of contaminated food and feed when contamination is suspected. Affected populations should be assessed for exposure (such as measuring contaminants in blood or breast milk) and effects (such as clinical follow-up for ill-health signs).

What Should Consumers Do to Reduce Exposure Risk?

Using less fat from meat and consuming low-fat dairy products may reduce exposure. A balanced diet including sufficient fruit, vegetables and grains also helps avoid excessive exposure from a single source. This is a long-term strategy for reducing body burdens and is probably necessary for girls and young women to reduce future fetal exposure. Dioxins accumulate more in obese people and those with more body fat than in those with less. Obesity’s increased cancer risk may involve dioxins as an important mechanism previously little recognized. Because breast milk has high fat content and is high in the human food chain, breastfed children are classified as "highly exposed to dioxins."

Nevertheless, consumers’ ability to reduce their own exposure is somewhat limited.

What Is Needed to Identify and Measure Dioxins in the Environment and Food?

Quantitative chemical analysis requires sophisticated / advanced methods available in a limited number of laboratories worldwide. Analysis costs are very high and vary by sample type, ranging from 1000 US dollars for a single biological sample to several hundred thousand US dollars for comprehensive assessment of dioxin releases from an incinerator.

Biological (cell- or antibody-based) screening methods are increasingly being developed and validated for food and feed samples. They allow more analyses at lower cost; positive screening results must be confirmed by more complex chemical analyses.

Dioxin-Related Activities in Turkey

In 2015, "Turkish Food Codex Communiqué on Sampling, Sample Preparation and Analytical Method Criteria for Official Control of Levels of Dioxins, Dioxin-Like Polychlorinated Biphenyls and Non-Dioxin-Like Polychlorinated Biphenyls in Certain Foods" was published (see). The "Packaging and Dioxin Laboratory" of the İstanbul Food Control Laboratory Directorate analyzes dioxins, furans, dioxin-like polychlorinated biphenyls and indicator polychlorinated biphenyls in food and feed. Food samples use EPA 1613 and EPA 1668B methods; feed samples use TS EN 16215.

Methods used at the Packaging and Dioxin Laboratory are based on nationally and internationally accepted ISO and Turkish Standards and Turkish Food Codex communiqués. Technological developments are reportedly followed to obtain faster, more reliable results.

For food and feed, "Dioxin, Dioxin-Like PCB and Indicator PCB (ICES6)" analysis pricingwas reported as 4290 TL (for the İstanbul Food Control Laboratory Directorate 2019 Analysis Unit Price List, see).

WHO Activities on Dioxins

The World Health Organization first published global estimates of foodborne disease burden in 2015. Dioxin effects on fertility and thyroid function were considered, and even considering only these two endpoints, exposure was shown to contribute substantially to foodborne disease burden in some regions.

Reducing dioxin exposure is an important public health objective for reducing disease. To guide acceptable exposure levels, WHO held expert meetings to determine tolerable dioxin intake.

In 2001, the Joint United Nations Food and Agriculture Organization (FAO) / WHO Expert Committee on Food Additives (JECFA) performed an updated comprehensive risk assessment of PCDDs, PCDFs and “dioxin-like” PCBs.

To assess long- or short-term health risks, total or average intake should be evaluated over months, and tolerable intake over at least 1 month. Experts set the maximum tolerable monthly dioxin intake at 70 picograms / kg per person. This is the amount that can be consumed over a lifetime without detectable health effects.

In collaboration with FAO through the Codex Alimentarius Commission, WHO established a “Code of Practice for the Prevention and Reduction of Dioxin and Dioxin-Like PCB Contamination in Food and Feed.” It guides national and regional authorities on preventive measures.

WHO also oversees the Global Environment Monitoring System’s Food Contamination Monitoring and Assessment Programme. Commonly known as GEMS / Food, it provides information on levels and trends of food contaminants through participating laboratories in more than 50 countries. Dioxins are included in this monitoring program.

WHO has also conducted periodic studies of dioxin levels in breast milk, assessing human exposure from all sources. Recent exposure data show that measures controlling dioxin releases in some developed countries have significantly reduced exposure since 2014. Data from developing countries are incomplete and do not yet permit time-trend analysis.

WHO continues these studies with the United Nations Environment Programme (UNEP) in the context of the “Stockholm Convention,” an international agreement to reduce emissions of certain persistent organic pollutants (KOK), including dioxins. Actions are being considered to reduce production of dioxins during incineration and manufacturing. WHO and UNEP conduct global breast milk surveys, including in many developing countries, to monitor worldwide contamination trends and effectiveness of Stockholm Convention measures.

Dioxins occur as complex mixtures in the environment and food. To assess the potential risk of the entire mixture, the concept of toxic equivalency has been applied to this pollutant group.

Through expert advisers, WHO established and regularly reassessed toxic equivalency factors (TEF) for dioxins and related compounds. WHO-TEF values applicable to humans, mammals, birds and fish have been determined.