Dioxin-like chemicals in soil and sediment from residential and industrial areas in central South Africa Claudine Nieuwoudt a, * , Laura P. Quinn a , Rialet Pieters a , Ilse Jordaan a , Maret Visser a , Henrik Kylin b,c , Anders R. Borgen d , John P. Giesy e,f,g,h , Henk Bouwman a a School of Environmental Sciences and Development (Zoology), North-West University, Potchefstroom Campus, Private Bag X6001, Potchefstroom 2520, South Africa b Norwegian Institute for Air Research, The Polar Environmental Centre, NO-9296 Tromsø, Norway c Department of Aquatic Science and Assessment, Swedish University of Agricultural Sciences, P.O. Box 7050, SE-75007 Uppsala, Sweden d Norwegian Institute for Air Research, P.O. Box 100, NO-2027 Kjeller, Norway e Zoology Department and Center for Integrative Toxicology, Michigan State University, East Lansing, MI 48824, USA f Department of Biomedical Veterinary Sciences and Toxicology Centre, University of Saskatchewan, Saskatoon, SK, Canada S7N 5B3 g Department of Chemistry and Biology, City University of Hong Kong, Kowloon, SAR, China h School of Environment, Nanjing University, Nanjing, China article info Article history: Received 12 February 2009 Received in revised form 28 April 2009 Accepted 28 April 2009 Available online 29 May 2009 Keywords: PCDD/Fs PCBs H4IIE Persistent organic pollutants Gauteng abstract Persistent organic pollutants (POPs) are a global concern due to their ubiquitous presence and toxicity. Currently, there is a lack of information regarding POPs from South Africa. Here we report and interpret concentrations of polychlorinated dibenzo-p-dioxins (PCDDs), -dibenzofurans (PCDFs) and co-planar- biphenyls (PCBs) in soils and sediments collected from central South Africa. High resolution gas chroma- tography–high resolution mass spectrometry (HRGC/HRMS) and the H4IIE-luc bio-assay were used to identify and quantify individual PCDD/F congeners and to report the total concentration of 2,3,7,8-tetra- chloro dibenzo-p-dioxin equivalents (TCDD-EQ), respectively. TCDD-EQs determined by use of the bio- assay, and concentrations of WHO 2005 -TEQ (toxic equivalents) determined by chemical analysis, were similar. The limit of detection (LOD) for the bio-assay was 0.82 and 2.8 ng TCDD-EQ kg 1 , dw for sediment and soil, respectively. EQ20 concentrations determined by use of the bio-assay ranged from <LOD to 70 ng TCDD-EQ kg 1 , dw for soil, and from <LOD to 45 ng TCDD-EQ kg 1 , dw for sediment. Concentrations of WHO 2005 -TEQ in soils were generally greater than those in sediments, and soils from the industrial area of Vanderbijlpark and the residential area of Klerksdorp contained the greatest concentrations. Based on the congener-specific HRGC/HRMS analyzes, concentrations of WHO 2005 -TEQ ranged from 0.12 to 32 ng WHO 2005 -TEQ kg 1 , dw in sediments, and between 0.34 and 20 ng WHO 2005 -TEQ kg 1 , dw in soils. The sources, processes and threats that govern and are associated with the lesser concentrations in sediment and greater concentrations in soils need further investigation. Ó 2009 Elsevier Ltd. All rights reserved. 1. Introduction Persistent organic pollutants commonly referred to as POPs, are a global concern. These substances are capable of long-range trans- port and have been dispersed world-wide, affecting areas where they have never been used or produced. Their physico-chemical characteristics, which include hydrophobicity and resistance to degradation, make these pollutants a challenge to control (Loh- mann et al., 2007). Some of these chemicals are endocrine-disrup- tive and toxic, and have the ability to bio-accumulate in food webs, posing significant health threats to humans, animals and the envi- ronment (Klánová et al., 2007). In May 1995, the United Nations Environment Programme (UNEP) initiated work on the Stockholm Convention (SC) on POPs with the intention of reducing, and ultimately eliminating these pollutants. South Africa signed and ratified the treaty on 4 Septem- ber 2002; on 17 May 2004, the SC on POPs entered into force for parties to the Convention (Bouwman, 2004). As a party to the Con- vention, South Africa is legally obligated to abide by the objectives of the treaty, and is encouraged to support research on POPs. In South Africa, some studies have been conducted into the dis- tributions of selected POPs, such as the intentionally released insecticide DDT, but little is known about the unintentionally re- leased POPs. The latter include polychlorinated dibenzo-p-dioxins (PCDDs), polychlorinated dibenzofurans (PCDFs) and co-planar (mono- and non-ortho-substituted congeners) polychlorinated biphenyls (PCBs), collectively known as dioxin-like chemicals (DLCs). PCDD/Fs (PCDDs and PCDFs) are produced as by-products 0045-6535/$ - see front matter Ó 2009 Elsevier Ltd. All rights reserved. doi:10.1016/j.chemosphere.2009.04.064 * Corresponding author. Tel.: +27 18 299 2512; Mobile: +27 83 308 2764; fax: +27 18 299 2503. E-mail address: claudine.nieuwoudt@nwu.ac.za (C. Nieuwoudt). Chemosphere 76 (2009) 774–783 Contents lists available at ScienceDirect Chemosphere journal homepage: www.elsevier.com/locate/chemosphere