Temporal trends of legacy POPs in Arctic biota, an update ☆ Frank Rigét a, ⁎, Anders Bignert b , Birgit Braune c , Jason Stow d , Simon Wilson e a National Environmental Research Institute, University of Aarhus, PO Box 358, DK-400, Roskilde, Denmark b Contaminant Research Group, Swedish Museum of Natural History, PO Box 50 007, S-104 05 Stockholm, Sweden c Environment Canada, National Wildlife Research Centre, Carleton University, Raven Road, Ottawa, Canada K1A 0H3 d Indian and Northern Affairs Canada, Northern Contaminants Program, 10 Wellington St. Gatineau Quebec, Canada K1A OH4 e Arctic Monitoring and Assessment Programme (AMAP) Secretariat, PO Box 8100 Dep. N-0032 Oslo, Norway abstract article info Article history: Received 13 May 2009 Received in revised form 10 July 2009 Accepted 20 July 2009 Available online 15 August 2009 Keywords: Temporal trends Arctic POPs Biota A statistically robust method was applied to 316 time-series of ‘legacy’ persistent organic pollutants (POPs) in Arctic biota from marine, freshwater and terrestrial ecosystems with the purpose of generating a ‘meta- analysis’ of temporal trend data collected over the past two to three decades for locations from Alaska in the west to northern Scandinavian in the east. Information from recently published temporal trend studies was tabulated and comparisons were also drawn with trends in arctic air. Most of the analysed time-series of legacy POP compounds showed decreasing trends, with only a few time-series showing significantly increasing trends. Compounds such as α-HCH, γ-HCH and ΣDDT had a relatively high proportion of time- series showing significantly decreasing trends; ΣCHL had the lowest proportion. β-HCH was an exception, where long-range transport through the ocean, and not the atmosphere, may explain several increasing trends that were detected in the Canadian Arctic. Moving east from the Canadian Arctic there was a trend towards a greater proportion of significantly decreasing trends. Several time-series for DDE and ΣDDT showed significantly non-exponential trends, most often with a period of relative stability followed by a decrease. The median ‘minimum detectable annual change within a 10-year period’ for all of the time-series considered was 12% which did not meet the desirable level of statistical power capable of detecting a 5% annual change with a significance level of 5% within a 10-year period. The trends observed in the biota were consistent with decreasing trends of legacy POPs reported for Arctic air which appear to follow historic decreases in emissions. However, recent decreases in air are also starting to show signs of levelling off which may be an indication that atmospheric concentrations and, consequently those in the biota, are being less driven by primary sources and more by environmental processes and degradation. © 2009 Elsevier B.V. All rights reserved. 1. Introduction Persistent organic pollutants (POPs) are chemicals that have a long-lifetime in the environment, and therefore have the potential to be transported over long distances. Many POPs can enter food-webs, accumulating in wildlife and people. The Arctic is believed to act as a sink for such chemicals (Macdonald et al., 2000). Several global and regional conventions have been developed with the goal of eliminat- ing or reducing emissions of persistent organic pollutants. The Stockholm Convention on Persistent Organic Pollutants addresses twelve priority POPs, while the POPs Protocol to the UN-ECE Convention on Long-range Transboundary Air Pollution (UN-ECE LRTAP) covers an additional four. POPs that have been banned or regulated are sometimes referred to as ‘legacy’ POPs, because present day contamination is largely a ‘legacy’ of past releases; this review deals with some of these legacy POPs. Despite the fact that use of these chemicals has either been phased-out or restricted, they are still found in the environment at levels that may cause negative effects to the health of individual animals and in some cases severe impacts on animal populations. Humans living in the Arctic and eating certain traditional foods can receive high dietary exposure to some legacy POPs and may also suffer adverse health effects from these compounds (Van Oostdam et al., 2005). Temporal trend studies are an important means of assessing the fate of contaminants in ecosystems. They can provide a first warning that potentially harmful compounds may be increasing in selected biota (indicator organisms) in the ecosystem. Temporal trend studies can also indicate whether regulatory actions aimed at reducing inputs of harmful chemicals to the environment are proving successful, or whether environmental levels are approaching threshold values. As indicated above, the objectives of temporal trend studies can differ and it should be stressed that an individual temporal trend study should be carefully designed to meet its intended objective based on sound statistical considerations. Also, the objectives should be Science of the Total Environment 408 (2010) 2874–2884 ☆ This paper is a contribution to the AMAP POPs assessment. ⁎ Corresponding author. Tel.: +45 4630 1948; fax: +45 4630 1914. E-mail address: ffr@dmu.dk (F. Rigét). 0048-9697/$ – see front matter © 2009 Elsevier B.V. All rights reserved. doi:10.1016/j.scitotenv.2009.07.036 Contents lists available at ScienceDirect Science of the Total Environment journal homepage: www.elsevier.com/locate/scitotenv