A never-ending story and lessons learned.
At the beginning of the first dioxin crises at the end of the last century, we did not anticipate that they would continue to pop up as a problem in the world for so long and that so many unexpected dioxin sources existed in the feed and food sector (see the figure on page 46). Over time, we have learned many lessons about how dioxins can enter the feed/food chain through many different industrial processing steps occurring in many countries. There have been many multi-national dioxin crises with global implications (Behnisch 2005, 2011; Codex 2017, 2018; EFSA 2012; Fink-Gremmels 2012; Motarjemi 2013; Petrlik 2018, 2019; Weber 2018; Malisch 2017; McEvoy 2016; Vugt-Lussenburg 2013). During the first few dioxin crises, the individual countries where they occurred had not yet established national legal dioxin limits. After the EU guidelines appeared in 2001, regular monitoring programs (by national or industrial associations) using screening and confirmatory analysis were instituted, resulting in the detection of many new and unexpected dioxin/PCBs incidents that led to international feed/food scandals. Other non-EU countries either set up strict limits (e.g. USA, see FDA 2019) or used EU standards as an import benchmark (e.g. Russia, China). From these first experiences, different formation and distribution patterns of dioxins and dioxin-like compounds (e.g. PCBs, PCNs, PBDD/Fs, see Behnisch 2001) in the environment and food chain were identified. At the beginning of nearly every dioxin/PCB crisis, the source of contamination was unknown and the original source was detected only by the intensive detective efforts of food dioxin experts without the benefit of cooperation with environmental experts in most cases. The surprising and unforeseen impact of many kinds of dioxin contamination sources (e.g. PCP-treated wood as a fuel source for feed drying, PCB oils mixed with plant oils, several minerals from mining, all kinds of thermal processes with dioxin precursors, waste burning, or pesticides; see Behnisch 2005, Codex 2017 and 2018, Malisch 2018, Weber 2018), which also play a role in feed/food recycling, has been to cause further dioxin scandals affecting the global feed and food chain, making it very difficult to predict and protect populations from future dioxin scandals.
In all these incidents, the demand for dioxin analyses temporarily increased dramatically, often beyond the capacities of local or national laboratories. Only a few accredited international laboratories have the capacity to process more than 300 samples per week. Compared to time- and cost-intensive confirmatory chemical analyses (by HRGC/HRMS or GC/MS/MS), screening tests such as CALUX reporter gene assays require only minimal effort and cost to accelerate and extend laboratory capacity (Behnisch 2005, 2010, 2011, 2018), rendering these screening tests advantageous both for bigger feed/food exporting countries as well as for countries equipped with less analytical capacity (see India, UNIDO 2011; Codex 2018). Fortunately, in most of the dioxin crises described here, only a small percentage of samples tested positive, making screening tests ideal in these situations. Despite many dioxin crises in the feed/food sector, there has been no significant increase in environmental testing to avoid further dioxin crises. Industrial processes in the metal industry, PVC production, mining, waste incine
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