Dioxins and PCBs in food and feed - a solved topic?

Ten years since the last dioxin scandal: What has happened in the meantime

Feb 2021. Both dioxins and PCBs are now ubiquitously distributed in the environment. Approximately 90% of the total human exposure to this group of environmental pollutants is due to the consumption of food. Dioxins became known worldwide through a chemical accident in 1976 near Seveso, Italy, in which 2,3,7,8-TCDD was released, as well as by the use of the defoliant Agent Orange in Vietnam. In later years, too, these groups of pollutants were repeatedly in the focus of public attention, especially in relation to their occurrence in food and animal feed.

Examples of these so-called "dioxin scandals" with transnational relevance are^[1]:

Citrus pulp, Brazil (1998): use of highly contaminated lime for the production of citrus pulp pellets (feeding stuff)
Belgian dioxin crisis(1999): an admixture of fats and oils contaminated with pentachlorophenol and PCBs to fats for feeding purposes
Kaolinite (2004): use of potato peels from food production as animal feed, where the clay mineral kaolinite was used to separate high-starch and low-starch potatoes
Guar gum, India (2007): use of pentachlorophenol contaminated with dioxins in the production of guar gum
Buffalo Milk Mozzarella, Italy (2007/2008)
Pork meat, Ireland (2008): use of feed contaminated in the drying process (production of drying gas from PCB-contaminated fuel oil)

Most recently, dioxins and PCBs made headlines in Germany in early 2011. Technical fats contaminated with PCBs entered the feed chain and caused the closure of pig and chicken farms, the emergency slaughter of laying hens and the disposal of chicken eggs as hazardous waste.

Dioxins and Polychlorinated biphenyls (PCBs)

The term "dioxins" describes a specific pollutant group of chlorinated and aromatic hydrocarbons known as polychlorinated dibenzodioxins and -furans or PCDD/Fs for short. Dioxins were never produced intentionally by humans, but can be formed as unwanted by-products in thermal processes in the presence of chlorine. In particular, 17 of the total of 210 individual compounds (so-called congeners) of this group of pollutants are considered toxic. The most toxic of these congeners is 2,3,7,8-tetrachlorodibenzodioxin (2,3,7,8-TCDD), which has also become known as "Seveso dioxin".

Polychlorinated biphenyls (PCBs) are also chlorinated hydrocarbons whose chemical structure is related to that of dioxins. This group of substances comprises 209 different congeners, 12 of which have toxic properties comparable to those of dioxins. They are therefore called dioxin-like PCBs or DL-PCBs for short. PCBs were produced as technical mixtures until the 1980s and used in various applications (e.g. in transformer or hydraulic oil, in sealants and paints).

Maximum levels for dioxins and PCBs in the EU

To protect humans, maximum levels and action levels for food and feed were set in the EU as early as 2001, in addition to strategies to reduce contamination with PCDD/Fs and PCBs in the environment. An overview of these current limit values can be found in our technical data sheets:

The increase in demand for dioxin and PCB analysis and the reasons behind it

Especially after the PCB incident in 2011, Eurofins GfA Lab Service GmbH, the competence centre for dioxins & persistent organic compounds (POPs) in the Eurofins laboratory network, noticed an increased demand for dioxin and PCB analyses in food and feed. Although the group of DL-PCBs was also included in the concept of legal maximum levels as early as 2006, the demand for PCB analyses has only increased significantly since 2011, as the following graph is showing.

Ratio of the number of PCB to PCDD/F tests in food and feed at Eurofins GfA Lab Service GmbH

Since 2011, the issue of dioxins and PCBs in food or feed has no longer been in the focus of public attention. Does the lack of further media coverage mean that dioxins and PCBs are no longer an issue? In 2011, German politics introduced a reporting obligation for analytical service providers and a notification obligation for food and feed business operators regarding dioxins and PCBs as a reaction to the PCB incident. These measures may have made a contribution here at least leading to more awareness along the value chain for food and feed. Immediately increasing sample numbers also point to more intensive monitoring of these environmental pollutants as a consequence of this incident. Such monitoring allows increasing dioxin and/or PCB concentration levels to be detected earlier and causative sources to be identified and resolved.

Outlook: Monitoring of dioxin and PCB contamination remains essential

The publication of a scientific opinion by the European Food Safety Authority (EFSA) in 2018 showed that human exposure to dioxins and PCBs continues to pose a health risk (please see our web news European Food Safety Authority: focus on environmental contaminants). The new health-based guideline values published at that time could lead to a reduction of the currently valid maximum levels in the long term. Backgrounds of previous "scandals" have also shown that product groups that have not been in the focus of previous monitoring can suddenly become the subject of media coverage. For these reasons we recommend to at least maintain the intensity of monitoring of dioxins and PCBs in food and feed in order to avoid the possibility of further local or even global events with increased dioxin and/or PCB concentrations.

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References

[1] R. Malisch: Incidents with Dioxins and PCBs in Food and Feed - Investigative Work, Risk Management and Economic Consequences. Journal of Environmental Protection 8 (2017) 744-785