Monitoring dioxins and PCBs in eggs as sensitive indicators for environmental pollution and global contaminated sites and recommendations for reducing and controlling releases and exposure

This review compiles information on PCDD/F- and PCB-contaminated eggs from 20 years of global egg monitoring around emission sources in four continents conducted by the International Pollutants Elimination Network (IPEN) and Arnika as well as a compilation of data from scientific literature. IPEN monitored 127 pooled egg samples including samples from 113 chicken flocks at potential PCDD/F- and PCB-contaminated sites around priority sources listed in the Stockholm Convention (e.g. waste incinerators, metal industries, cement plants, and open burning). 99 (88%) of pooled egg samples were above the EU maximum limits for PCDD/Fs (2.5 pg PCDD/F-TEQ/g fat) or the sum of PCDD/Fs and dioxin-like PCBs (5 pg PCDD/F-PCB-TEQ/g fat). Children consuming such eggs exceed the tolerable weekly intake (TWI). This demonstrates that close to 90% of these areas were not safe for the production of free-range eggs. Sixteen out of the 113 egg samples (14%) were contaminated above 50 pg TEQ/g fat and exceeded the EU maximum limit more than 10 times. From the 26 pooled egg samples around incinerators 24 (92%) exceeded the limit with a mean of 43.1 pg TEQ/g fat (2.6–234 pg TEQ/g). All 21 egg samples around metal industries (4.4–112.6 pg TEQ/g fat) were above limits with mean concentration of 26.0 pg TEQ/g fat. Also all 7 egg samples measured at e-waste recycling sites were above limits (mean 308 pg TEQ/g fat). In 58 (51%) pooled egg samples the PCB-TEQ was above 5 pg TEQ/g fat exceeding the EU maximum limit with dioxin-like PCBs alone. This highlights the role of commercial PCBs for global contamination with dioxin-like compounds. It was discovered that around metal industries, shredder plants, open burning sites of e-waste and dump sites, a high share of contamination was caused by dl-PCBs. This clearly shows severe PCB release from the end-of-life management of PCB-containing equipment in developing countries. Also highly contaminated eggs were found at many sites where plastic was incinerated. The highest contaminated egg sample ever measured came from an e-waste site in Ghana and had 856 pg TEQ/g fat plus 300 pg TEQ from brominated dioxins (PBDD/Fs). Other extreme PCDD/F contaminations of eggs were found at a chlor-alkali site (514 pg TEQ/g fat), Agent Orange contaminated areas in Vietnam (490, 249 and 246 pg TEQ/g fat) and e-waste sites (568 and 520 pg TEQ/g fat). Where DR CALUX® bioassay revealed higher TEQ compared to measured PCDD/F-PCB-TEQ in IPEN studies, polybrominated PBDD/F were also measured and detected up to 300 pg TEQ/g fat at e-waste sites. One positive outcome from the IPEN studies is that all 10 pooled supermarket eggs in developing countries were below regulatory limit. Policy recommendations are made including: a systematic assessment of areas around PCDD/Fs and PCBs sources; measures for reduction of exposures of populations; urgent control of emission sources including PCB equipment, the open burning of plastic, and the use of plastic as fuel in boilers/incinerators in developing countries without air pollution control. Furthermore, soil limits need to be re-assessed and lowered for free-range poultry.