Polychlorinated diphenylethers: origin, analysis, distribution, and toxicity in the marine environment

PCDEs are present as impurities in chlorophenol preparations, which are often used as wood preservatives. Other sources of PCDEs such as municipal waste incinerators seem to be of minor importance. It is estimated that, worldwide 250-2500 metric tons of PCDEs have been produced, which is a lesser amount compared to the production figures of polychlorinated biphenyls (PCBs), polybrominated diphenylethers (PBDEs), or polychlorinated naphthalenes (PCNs). The required analytical methods are rather complex and are comparable to methods used for polychlorinated dibenzo-p-dioxins (PCDDs) and furans (PCDFs). Gas chromatography with low resolution or high resolution mass spectrometry or with electron-capture detection is recommended for the final determination of PCDEs. There is only limited information on the presence of PCDEs in the marine environment. High concentrations of PCDEs were found in Baltic white-tailed sea eagles (up to 13 mg/kg lipid weight per congener). Total PCDE concentrations of 50-300 micrograms/kg were reported in cod liver oil samples. PCDEs are immunotoxic and show a clear potency as inducers of hepatic microsomal AHH and EROD activity. Although PCDE concentrations in marine organisms are expected to be lower than those of PCBs, PBDEs, and PCNs, because of their toxic properties, persistence, and hydrophobic and bioaccumulative character and because of the limited information on these concentrations in marine organisms, further research on these concentrations in marine organisms is recommended.