Dioxins in food: Preventing and controlling contamination
Dioxins are known carcinogens, and their presence in food and water intended for human consumption is tightly regulated around the world. In the article, we provide a brief overview of dioxins, their potential health effects and steps that manufacturers should take to reduce dioxins in their food and food products.
What are dioxins?
Dioxins are one of several environmental pollutants that have been categorised as persistent organic pollutants (POPs), due to their chemical stability. There are actually 419 identified types of dioxin-related chemical compounds, but only about 30 of those possess a chemical structure considered to have significant toxicological properties. The term dioxin is sometimes also applied to chemically-related compounds such as polychlorinated biphenyls (PCBs), and there are some similarities between dioxins and dioxin-like PCBs in terms of their chemical behaviour and potential toxicity.
For the most part, dioxins are created as a by-product of industrial and manufacturing processes, including the manufacture of some herbicides and pesticides, as well as the incineration of solid and hospital waste. To a lesser extent, dioxins are also produced through natural processes, such as volcanic eruptions or forest fires. However, regardless of their initial source, dioxins typically make their way into the environment either through the application of contaminate sludge or sewage to farm land or pastures, the use of dioxin-contaminated pesticides and fertilisers, or from atmospheric deposits on land and water.
What are the primary sources of dioxins in food?
It is estimated that as much as 90 percent of dioxin exposure in humans is attributable to food and food products. Dioxins accumulate in the fat of animals and fish, and dioxin levels may be further exacerbated through environmental exposure or animal feed contamination. Foods with the highest dioxin concentrations include meat and poultry, eggs and dairy products, and fish, while green vegetables, fruits and grains typically have the lowest dioxin concentrations.
Depending on their occupation, some workers in the chemical and agricultural industry may be subject to additional dioxin exposure through the use of dioxin-containing chemicals or herbicides. However, due to its widespread presence in foods, most people have a certain level of dioxin in their bodies (the so-called body burden). Therefore, the primary goal in addressing dioxin contamination in humans is to reduce background exposure by reducing dioxin concentrations in foods and animal feeds.
What are the health effects of exposure to dioxins?
According to the World Health Organization, dioxins have been shown to have both short- and long- term effects on humans and animals. Short-term effects can include skin lesions, such as chloracne and patchy darkening of the skin, and altered liver function. Effects from long-term exposure include reproductive and developmental problems, damage to the immune system and interference with hormonal activity.
In animals, dioxin exposure through ingestion of contaminated feed can lower egg production in chickens and milk production in dairy cows. Other consequences of dioxin exposure in animals include weight loss, hypofertility, and a wide range of adverse health conditions.
Dioxins (specifically tetrachloro-dibenzo-para-dioxin, or TCDD) have been classified by WHO’s International Agency for Research on Cancer (IARC) as a “known human carcinogen,” posing excess risk for all types of cancer. However, certain populations including newborns and developing foetuses are far more sensitive to dioxin exposure and at greater risk from certain health effects.
How can dioxin exposure be controlled?
As previously noted, efforts to control dioxin exposure in humans are primarily focused on reducing dioxin at its source. This includes the proper incineration and disposal of dioxin-contaminate materials in order to minimise their ability to contaminate soil and water and to reduce the risk of dioxin contamination of agriculture products and animal feed.
For manufacturers and producers, the most critical steps to reduce dioxin exposure in food and food products involve adopting good manufacturing and hygienic practices in production, processing and distribution activities. Further actions include active monitoring of dioxin levels in food and food ingredients to ensure that established maximum exposure levels are not exceeded.
How are dioxins in foods measured?
The accurate measurement of dioxin concentrations in food is more complicated than that required for other food contaminants, and generally requires the use of high resolution gas chromatography/high resolution mass spectrometry (HR-GC/HR-MS). This highly sophisticated assessment technique requires a significant investment in technology and equipment. As a result, only a relatively small number of independent testing laboratories have the equipment and expertise required to conduct dioxin testing.
To help minimise dioxin levels in food and food products, manufacturers should periodically assess incoming raw food ingredients as well as final food products. The frequency of such testing depends on the degree of anticipated risk associated with the product’s ingredients as well as testing results from previous analysis.
How can we help?
Located near Florence, Italy, TÜV SÜD’s pH Laboratory is one of the few testing laboratories in the world that specialises in testing dioxins and other food contaminants. Equipped with state-of-the-art GCMS technology, the laboratory is accredited to conduct testing in accordance with EPA 1613b (dioxins and furans analysis in foods) and EPA 1668c (dl-PCB analysis in foods). In addition the laboratory is staffed with experts and technicians with extensive food contaminant testing experience, including the testing of dioxins.
For additional information about TÜV SÜD’s dioxin testing services, contact us here.
 “Dioxins and their effects on human health,” World Health Organization, Fact sheet No. 225, June 2014. Available at here (as of 29 February 2016).