Monitoring dioxins and PCBs in eggs as sensitive indicators for environmental pollution and 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 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. A range of 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.