Executive Summary 



than a factor of four were found for these sample collections and is similar to between-species 

 differences reported elsewhere. 



Frozen archive samples are being maintained temporarily at GERG for future use of the 

 UNESCO-IOC and UNEP programs. Shell samples representative of the entire sample set were 

 sent to Dr. Ruth Turner at the Museum of Comparative Zoology , Harvard University, Cambridge, 

 Massachusetts, USA for identification of several unknown bivalve species which could not be 

 identified by local scientists. The collection of shells is now stored at Harvard University as a 

 reference set for species identification. 



The initial focus of the International Mussel Watch Program was on chlorinated pesticides 

 and individual chlorobiphenyls of the polychlorinated biphenyls (PCBs). The initial set of target 

 analyte chlorinated pesticides were: aldrin, endrin, dieldrin, chlordanes, DDT family, heptachlor, 

 heptachlor expoxide, hexachlorbenezene (HCB), alpha-hexachlorocyclohexane (alpha-HCH), 

 beta- hexachlorocyclohexane (beta-HCH), Lindane (gamma-HCH), trans-nonachlor, and 

 methoxychlor. A Quality Control and Quality Assurance( QA/QC) program was coordinated by the 

 Secretariat at WHOI and provided a framework for evaluation of the field data submitted by each of 

 the central analytical facilities. Timing of funding to the central analytical facilities forced the initial 

 QA/QC exercise to coincide with the analysis of the field samples, with the attendant risk of finding 

 major differences in data between laboratories after the first set of field samples were analyzed. 

 However, the QA/QC results were generally satisfactory to excellent and comparable to similar 

 between-laboratory comparisons of experienced laboratories for these analytes. 



Participating Host-Country laboratories also received a set of QA/QC samples and standard 

 solutions of the analytes and also several of these laboratories analyzed comparable portions of 

 field samples. Results of the QA/QC exercise for the national laboratories were for their own 

 individual use and are not reported in detail. 



A total of 76 sites were sampled during this Initial Phase. Analyses show that 

 concentrations of chlorinated pesticides were not elevated for most of the stations and were similar 

 to the range of concentrations found in the United States, based on the National Oceanic and 

 Atmospheric Administration's National Status and Trends (NOAA-NS&T) data set during the late 

 1980s to early 1990s. 



Several stations in this region show elevated concentrations of one or more chlorinated 

 pesticides compared to the rest of the data. Most of these stations were near urban or agricultural 

 areas. Individual chlorobiphenyl concentrations were generally lower for the in Latin America data 

 set in comparison to the NOAA-NS&T dataset for the U.S. coast, perhaps indicating less use 

 and/or release of PCBs in this region in comparison to the United States. 



GERG also undertook analyses of selected polycyclic aromatic hydrocarbons (PAH) under 

 the auspices of the IMW project and with the approval of the participants at a preliminary data 



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