Organochlorine accumulation on a highly consumed bivalve (Scrobicularia plana) and its main implications for human health T.F. Grilo a, ⁎, P.G. Cardoso b , P. Pato c , A.C. Duarte c , M.A. Pardal a a CFE — Centre for Functional Ecology, Department of Life Sciences, University of Coimbra, PO-BOX 3046, 3001-401 Coimbra, Portugal b IMAR–CMA–Marine and Environmental Research Centre, Department of Life Sciences, University of Coimbra, 3004-517 Coimbra, Portugal c Department of Chemistry, & Center for Environmental and Marine Studies (CESAM), University of Aveiro, 3810-193 Aveiro, Portugal HIGHLIGHTS • Contamination by PCBs and HCB decreased with the distance to the pollution source. • Deeper sediment layers presented higher PCB and HCB levels than superficial ones. • Contamination exceeds sediment quality guidelines, inducing toxic effects in biota. • Scrobicularia plana tended to bioaccumulate PCBs throughout its lifespan. • Bivalves incorporate 0.4g∙y−1 of PCBs from sediments, free for trophic transfer. abstract article info Article history: Received 14 February 2013 Received in revised form 30 April 2013 Accepted 30 April 2013 Available online xxxx Editor: Adrian Covaci Keywords: PCBs HCB Scrobicularia plana Bioaccumulation Trophic transfer Human health Contamination by polychlorinated biphenyls (PCBs) and hexachlorobenzene (HCB) was investigated along a spatial gradient in water, sediments and in commercially important bivalve species Scrobicularia plana, from Ria de Aveiro (Portugal). Organochlorines dissolved in water were below detection limit and concerning suspended particulate matter, only PCBs were quantified, ranging from 3.8 to 5.8 ng ∙ g −1 DW (Σ 13 PCBs). There was a distinct spatial gradient regarding PCB accumulation in sediments. The highest concentrations were found in deeper layers and closest to the pollution source, decreasing gradually along a 3 km area. Con- tamination in sediments exceeded the Canadian and Norwegian sediment quality guidelines, inducing poten- tial toxic effects in related biota. PCBs tended to bioaccumulate throughout S. plana lifespan but with different annual rates along the spatial gradient. The maximum values were found in older individuals up to 3 + years old, reaching 19.4 ng ∙ g −1 DW. HCB concentrations were residual and no bioaccumulation pattern was evi- dent. Congeners 138, 153 and 180 were the most accumulated due to their abundance and long-term persis- tence in the environment. In the inner area of the Laranjo Bay (0.6 km 2 ), the species was able to remove up to 0.4 g of PCBs annually from sediments into their own tissues, which is consequently free for trophic transfer (biomagnification). Concerning human health, and despite the high concentrations found in sediments, PCB levels in bivalves do not exceed the limit established by the European Union for fishery products and are largely below tolerable daily intake. Although PCBs in Scrobicularia plana are present at low levels, their impact to human health after consumption over many years might be harmful and should be monitored in future studies. © 2013 Elsevier B.V. All rights reserved. 1. Introduction Environmental contamination by persistent organic pollutants (POPs) has received increasing concern worldwide, reflecting the im- pact of anthropogenic activities over time. Organochlorine compounds such as polychlorinated biphenyls (PCBs) and hexachlorobenzene (HCB) are defined as POPs by the Stockholm Convention, which acts as a global treaty to protect human health and the environment from these chemicals (UNEP, 2001). Ranking among the top 5 priority hazardous substances along with arsenic, lead, mercury and vinyl chloride (ATSDR, 2007), PCBs were manufactured commercially in Europe from 1929 until the mid-1980s (OSPAR, 2010) and were primarily used in industry due to their insulat- ing and flame retardant properties. According to the Water Framework Directive (2000/60/EC), HCB is also identified as a priority hazardous substance and has been synthesized and used from the 1940s to the late 1970s as a fungicide for a variety of crops, being also applied in Science of the Total Environment 461–462 (2013) 188–197 ⁎ Corresponding author. Tel.: +351 239 836386; fax: +351 239823603. E-mail address: tfgrilo@student.biologia.uc.pt (T.F. Grilo). 0048-9697/$ – see front matter © 2013 Elsevier B.V. All rights reserved. http://dx.doi.org/10.1016/j.scitotenv.2013.04.096 Contents lists available at SciVerse ScienceDirect Science of the Total Environment journal homepage: www.elsevier.com/locate/scitotenv