摘要
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 dioxinlike 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(2.6e234 pg TEQ/g).All 21 egg samples around metal industries(4.4e112.6 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.
