Long-term trends of polychlorinated biphenyls and chlorinated pesticides in franciscana dolphin (Pontoporia blainvillei) from Southern Brazil Juliana Leonel a,c, * , Jose L. Sericano b , Gilberto Fillmann c , Eduardo Secchi d , Rosalinda C. Montone a a Laboratório de Química Orgânica Marinha, IO-USP, São Paulo, SP 05508-900, Brazil b Geochemical and Environmental Research Group, Texas A&M University, College Station, TX 77843, USA c Laboratório de Microcontaminantes Orgânicos e Ecotoxicologia Aquática, FURG, C.P. 474, Rio Grande, RS 96201-900, Brazil d Laboratório de Tartarugas e Mamífero Marinhos, Instituto de Oceanografia Grupo de Pesquisa ‘‘Ecologia e Conservação da Megafauna Marinha – EcoMega”, FURG, C.P. 474, Rio Grande, RS 96201-900, Brazil article info Keywords: Organochlorine Pontoporia blainvillei Franciscana dolphin Temporal trends Southern Brazil Pollution monitoring abstract Selected POPs were analyzed in blubber samples of Pontoporia blainvillei from Southern Brazil to appraise temporal trend over a 10 year period (1994–2004). Overall, levels of POPs were relatively low, especially when compared to Northern Hemisphere concentrations. Apart from Mirex and PCBs, which showed stable concentrations, DDTs, HCB, CHLs, Dieldrin levels presented a slight decrease over the studied period. In addition, the increase in the PCBs/DDTs ratio supports the idea that inputs of DDTs are decaying faster than PCBs. Ó 2009 Elsevier Ltd. All rights reserved. 1. Introduction Over the last two decades, there has been growing concern about the bioaccumulation and toxic effects of persistent organic pollutants (POPs) in marine ecosystems (Clark, 2001; Tanabe et al., 1994). POPs are a group of synthetic organic compounds that have been produced for industrial and agricultural purposes, or are by-products of other industrial processes. In addition to being resistant to degradation, most POPs are lipophilic and, conse- quently, tend to accumulate in organisms and biomagnify through- out the food chain reaching the highest levels in top predators (Clark, 2001). In this regard, marine mammals have been widely used as bio- indicators/biomonitors of POPs (Muir et al., 1990; Tanabe and Subramanian, 2006). Because they are long-lived, they are at the top of the aquatic food chain (Reijnders, 1986), they can transfer PCBs and chlorinated pesticides through lactation over generations and most have low capacity for xenobiotic degradation (Tanabe et al., 1988). Marine mammals may also be used to assess the bio- availability and bioaccumulation of selected POPs in the marine environment worldwide and over long time spans, and may pro- vide a model for human exposure to organochlorines from seafood consumption (Aguilar, 1987). Moreover, they can be considered as ‘‘model systems” for studying low-dose, long-term effects of pollu- tion by POPs (Tanabe and Subramanian, 2006). The franciscana, Pontoporia blainvillei, is a small cetacean with a distribution restricted to the southwest Atlantic Ocean (Bastida et al., 2007). Some studies have been done with this dolphin (Borrel et al., 1995; Kajiwara et al., 2004; O’Shea et al., 1981), but long- term temporal trends of POPs in this cetacean are unknown. Although several studies have indicated a continuous decrease of POP concentrations in cetaceans from the Northern Hemisphere (e.g. Borrel and Aguilar, 2007; Dietz et al., 2004), the only long- term study available in the Southern Hemisphere did not indicate a decrease, but rather slightly increasing concentrations in the minke whale (Balaenoooptera acutorostrata) from Antarctica (Aono et al., 1997). Organochlorine pesticides were not totally banned in South American countries, their use was only restricted from mid- eighties, but some are still allowed in pest control of tropical and subtropical epidemic disease (such as malaria), emergencies use in agriculture, wood preservations and forestation/reforestation activities (PNUMA, 2002). Although prohibited in most of the South American countries, in Brazil PCBs have been allowed in transform- ers already installed before their exchange for a PCB free-oil (Bar- reto et al., 1988). Other diffuse sources (for example, dumpsites) are also inputting PCBs to the environment. Considering these pos- sible sources it is still very important to appraise POPs levels and trends in South America. Therefore, the present study is the first at- tempt to assess long-term trends of selected POPs in blubber sam- ples of P. blainvillei from Southern Brazil. 0025-326X/$ - see front matter Ó 2009 Elsevier Ltd. All rights reserved. doi:10.1016/j.marpolbul.2009.10.011 * Corresponding author. Address: Laboratório de Química Orgânica Marinha, IO- USP, São Paulo, SP 05508-900, Brazil. Tel.: +55 11 3091 6570. E-mail address: juoceano@yahoo.com.br (J. Leonel). Marine Pollution Bulletin 60 (2010) 412–418 Contents lists available at ScienceDirect Marine Pollution Bulletin journal homepage: www.elsevier.com/locate/marpolbul