Contamination status and spatial distribution of organochlorine compounds in fishes from Nansei Islands, Japan Govindan Malarvannan a , Shin Takahashi a , Tokutaka Ikemoto a , Tomohiko Isobe a,b , Tatsuya Kunisue a , Agus Sudaryanto a,b , Toshihiko Miyagi c , Masaru Nakamura d , Shigeki Yasumura e , Shinsuke Tanabe a,⇑ a Center for Marine Environmental Studies (CMES), Ehime University, Bunkyo-cho 2-5, Matsuyama 790-8577, Japan b Senior Research Fellow Center (SRFC), Ehime University, Bunkyo-cho 2-5, Matsuyama 790-8577, Japan c Department of Environmental Science, Okinawa Prefectural Institute of Health and Environment, Ozato 2085, Nanjo, Okinawa 901-1202, Japan d Tropical Biosphere Research Center, University of the Ryukyu, Sesoko 3422, Motobu, Okinawa 905-0227, Japan e WWF Japan, Shiba 3-1-14, Minato-ku, Tokyo 105-0014, Japan article info Keywords: Organochlorines Fishes Risk assessment Nansei Islands Okinawa abstract Two species of fishes (n = 52; tilapia and mullet) from industrialized and urbanized areas of Okinawa Island (Manko-Noha river, Hija river and Shikaza river) and from a remote area of Ishigaki Island (Anparu mudflat), Japan were collected between August 2005 and July 2006, and analyzed for five organochlorine compounds (OCs), viz., DDTs, PCBs, CHLs, HCHs and HCB. Concentrations and the contamination patterns of OCs in fishes varied between locations. Considerable residue levels of OCs, especially CHLs and DDTs were found in both fishes from the main Okinawa Island. These levels were relatively higher than the reported values for seafood from Japanese coasts, indicating that even now pollution sources of these contaminants still exist in this region. On the other hand, lower concentrations of OCs were detected in fishes from Ishigaki Island waters than those of other Japanese coastal waters, suggesting that this region is less contaminated by OC contaminants. Ó 2011 Elsevier Ltd. All rights reserved. 1. Introduction Humans and the environment have been exposed to thousands of synthetic chemicals that did not exist before the industrial rev- olution. Persistent organic pollutants (POPs) have emerged as con- taminants of concern due to their widespread usage, ubiquitous environmental distribution, bioaccumulation potential, and toxic- ity (Iwata et al., 1993). POPs include a wide range of xenobiotic chemicals, such as the polychlorinated biphenyls (PCBs) and orga- nochlorine pesticides (OCPs), e.g., dichlorodiphenyltrichloroethane and its metabolites (DDTs), chlordane compounds (CHLs), hexa- chlorocyclohexane isomers (HCHs) and hexachlorobenzene (HCB). These chemicals have even been detected in remote polar regions with no historical usage, including the atmosphere (Kallenborn et al., 1998), water (Zi-wei et al., 2002), and biota (Riget et al., 2004). Wania and Mackay (1996) suggested that POPs may migrate to higher latitudes in a series of ‘‘jumps’’ character- ized by evaporation and condensation steps, aligned by seasonal temperature changes at mid-latitudes, known as the ‘‘grasshopper effect’’. The tropical regions of Asia are considered to be a prime source of many POPs of strategic geographical importance due to their extensive use and associated global atmospheric dispersion (Iwata et al., 1993). Nansei Islands, a chain of sub-tropical Islands located in the Southwestern end of Japan, is rich in endemic and sub-endemic fauna and flora. From a biodiversity conservation perspective, it is extremely important to conserve this archipelago. On the other hand, as Nansei Islands are in close proximity to rapidly industrial- izing countries such as China, Taiwan and other Southeast Asian countries, environmental pollution and adverse effects on ecosys- tems of the East China Sea (ECS) by hazardous chemicals are of serious concern. In this regard, our group has conducted monitor- ing surveys for POPs in the Asia-Pacific region using skipjack tuna (Katsuwonus pelamis) and mussel as bioindicators (Ueno et al., 2003; Monirith et al., 2003). Our results indicated that pollution by POPs such as DDTs is more serious in the ECS and coastal areas of China than in other regions of Asia. In Japan, enormous amounts of OCs such as DDTs and HCHs were used mainly during the 1960s (Tatsukawa, 1968), and CHLs were used as a termiticide till 1986 (Loganathan et al., 1989). Additionally, production and usage of technical PCBs and OCs were completely prohibited during the 1970s, while prohibition of technical CHL usage was enforced in 1986 (Tanabe et al., 1989). Although the use of OCs has been banned and/or restricted in almost all countries, including Japan, OC residues are expected 0025-326X/$ - see front matter Ó 2011 Elsevier Ltd. All rights reserved. doi:10.1016/j.marpolbul.2011.02.002 ⇑ Corresponding author. Tel./fax: +81 89 927 8171. E-mail address: shinsuke@agr.ehime-u.ac.jp (S. Tanabe). Marine Pollution Bulletin 63 (2011) 541–547 Contents lists available at ScienceDirect Marine Pollution Bulletin journal homepage: www.elsevier.com/locate/marpolbul