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PentachlorophenolReportTo read the report please click here. SummaryCurrent levels of pentachlorophenol in surface waters and sediments should not represent a risk to the marine environment in the North Sea region. This conclusion is based on 41 aquatic toxicity test results, plus 1983-97 North Sea monitoring results from estuarine/marine and river waters, and sediments. Applications of pentachlorophenolProduction and use of pentachlorophenol (PCP) has been restricted in Europe since the early 1980s. As a result, PCP usage has been declining since the early 1980s, falling to around 100 tonnes in 1996. Use of sodium pentachlorophenate (NaPCP) has been relatively stable since 1987, totalling some 1,000 tonnes in 1996. About 20-30 tonnes/year of pentachlorophenyl laurate (PCPL) are used in the EU (ERM 1997). PCP is currently imported and used in France, Spain, Portugal, Italy, and the UK. Other EU member states, and the remaining countries which border the North and Baltic Seas, have generally banned the use of pentachlorophenol-containing products. Since 1991, all pentachlorophenol-containing products sold and used in the EU are imported (EU production is banned under Directive 76/769/EEC). There are three forms: pentachlorophenol, sodium pentachlorophenate and pentachlorophenyl laurate (PCPL). Usage is restricted under Directive 91/173/EEC. The three main uses of pentachlorophenol-containing chemicals in the EU are currently:
Use of pentachlorophenol in timber treatment is restricted to industrial facilities. Treated wood cannot be used inside buildings or in materials which might come into contact with human or animal foodstuffs. Exceptions are made for certain sales and industrial/professional use of pentachlorophenol formulations on a case-by-case basis for remedial timber treatment, use as surface biocides, treatment of fibres and heavy-duty textiles not intended for clothing or decorative furnishings, and as industrial synthesising and/or processing agents. All amateur uses of pentachlorophenol-based formulations were revoked in July 1992. In 1987, a 4 ppm limit was set for dioxin concentrations in pentachlorophenol (Directive 91/173/EEC). Since then, levels of these and other micro-contaminants have fallen. For example, current batches of PCP and derivatives contain an average of 1.7 ppm of dioxins. Dioxin emissions to air are insignificant when pentachlorophenol-treated wood is burned under controlled conditions. Evaluation of environmental riskFor pentachlorophenol, the evaluation of toxicity was based on 41 aquatic toxicity test results, including 20 for fish, 14 for invertebrates, and 7 for plants, which were identified as being of the highest reliability (Reliability Level 1) according to the quality criteria recommended by the EU guidelines. Since considerable Reliability Level 1 marine toxicity data are available, the results of chronic toxicity studies with marine organisms were used, along with the appropriate assessment factors, to derive a final PNEC value of 1 µg/l. Based either on laboratory tests or field studies, a freshwater PNEC of 0.2 to 2 µg/l can be calculated. Since the form and toxicity of pentachlorophenol depend on the environmental pH, toxicity data were examined including a range of pH test conditions. This accounts, at least in part, for the wide range of results within each trophic level of organisms. Monitoring data were available for North Sea coastal and estuary waters, and for rivers that discharge to the North Sea. Recent data (1983-97) were used to calculate PEC values for the marine environment under different scenarios. Based on monitoring data from 1992-97 (which covers the period after which the EU and member states imposed restrictions on production and use of pentachlorophenol), the typical PEC in estuarine/marine waters was 0.01 µg/l. The highest average, or worst case, PECs were 0.24 µg/l (in the general vicinity of sources) and 0.79 µg/l (immediately adjacent to industrial outfalls) for coastal/estuarine waters and 0.76 µg/l for river waters during the period 1983-91. The worst case PECs during 1993-97 are 0.11 µg/l and 0.15 µg/l, for coastal/estuarine waters and river waters, respectively. The general trend from monitoring data is for concentrations to decrease with time in all surface waters. Monitoring data was obtained from the North Sea coast in Germany, the Netherlands and the UK. In estuary waters, average or median PCP concentrations have generally shown a decreasing trend with time during 1983-97. Data for North Sea estuaries was obtained from: Ijsselmeer, Ems Estuary, Scheldt Estuary (Netherlands); the southern Netherlands; Greatham Harbour and six English estuaries (UK); and Elbe and Weser estuaries (Germany). For sediments, the calculated PEC/PNEC ratios are also less than one, based on the most recent data (1995-97) for both coastal/estuarine and river systems. As with surface waters, the ratios were larger (sometimes exceeding one) in earlier years. This indicates that levels of pentachlorophenol in sediments have been decreasing over time and are currently at levels at which no adverse effects to aquatic systems are anticipated, under typical conditions in the North Sea. The marine PNECsed is 62 µg PCP per kg of sediment. For freshwater sediments, the PNECsed would be 12.4 to 124 µg/kg. In coastal and estuarine waters, the highest average PCP sediment concentration based on 77 samples analysed from 1991-94 was 26.5 µg/kg. All 33 samples analysed from the same locations in 1995-1997 were below the limit of detection (<10 µg/kg). In rivers, the highest average PCP sediment concentrations based on 244 samples analysed from 1985-94 was 29.7 µg/kg. Most of the 40 samples analysed from the same locations in 1995-1997 were below the limit of detection (<10 µg/kg). The highest average concentration was 11.25 µg/kg in samples where PCP was detected. It is known that pentachlorophenol is not persistent (this is confirmed by the decreasing levels in surface waters and sediments) and it is not expected to accumulate significantly in aquatic biota. Risk assessment conclusionWhen the environmental concentration of pentachlorophenol is compared with the probable no-effect level to give the PEC/PNEC ratio, that ratio based on typical coastal and estuarine water concentrations provides a safety margin of 100 between actual exposure and the level likely to give a negative environmental impact. The ratio based on worst case concentrations provides a safety margin of 9. This is based on the most recent monitoring data (1992-97), which reflect EU production and use restrictions. The safety margins are lower based on the most recent monitoring data in river waters. However, these take no account of the considerable dilution of pentachlorophenol as the rivers enter the North Sea estuaries and coastal waters, which would increase these safety margins. Current levels of pentachlorophenol in surface waters and sediments should not represent a risk to the marine environment in the North Sea region. Both surface waters and sediments are showing a decreasing trend in pentachlorophenol concentrations with time. Due to further restrictions on PCP use in Europe, it is expected that monitoring levels in water and sediments will continue to decrease. Summary table for PEC/PNEC ratios for pentachlorophenol
Risk assessment conclusions for sediments
North Sea Monitoring Data on pentachlorophenol
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