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he dechlorane family of flame retardants, which includes Mirex (also known as Dechlorane), Dechlorane Plus (DP), and Dechloranes (Dec) 602, 603, and 604, were manufactured at a facility along the Niagara River, upstream of Lake Ontario. Some of these compounds remain in use. In a previous study, we found Mirex and Dec602 to have greater bioaccumulation potentials than Dec604 and DP based on calculated biota-sediment accumulation factors (BSAFs). In this study, analogues of Dec604, containing fewer bromines and mixed substitutions of bromine and chlorine, were identified in Lake Ontario sediment and fish using high and ultrahigh resolution mass spectrometric techniques. The tribromo-Dec604 (Br3Dec604) analogue, known as Dechlorane 604 Component B (Dec604 CB), was present in lake trout and whitefish at concentrations of 10-60 ng/g lipid weight, approximately 50-200 times greater than concentrations measured for Dec604. In addition, BrDec604 and Br2Dec604 analogues, and mixed Br2Cl2Dec604, Br3ClDec604, Br2CIDec604, and BrCl2Dec604 analogues were also present. We have shown that solutions of Dec604 and Dec604 CB exposed to UV-light undergo photodebromination and give rise to the analogues found in sediment and fish. Dec604 CB and other lesser halogenated analogues of Dec604 show greater bioaccumulation potentials than Dec604, Dec602 and DP, based on BSAFs, which highlight the need to consider likely impurities and degradation products in the assessment of persistent, bioaccumulative, and toxic compounds. [ABSTRACT FROM AUTHOR]

Temporal trends and seasonal variation of Dechloranes (Dec) 602, 603, 604, and Chlordene Plus (CP) in Niagara River suspended sediment, a Lake Ontario sediment core, and Lake Ontario lake trout were investigated, with Mirex and Dechlorane Plus (DP) included for comparison. Temporal concentration trends were generally consistent in each of the media for all compounds with the lowest concentrations observed in or after the late 1990s. In Niagara River suspended sediments, all compounds showed seasonal variation over a year with distinct profiles observed. The relative concentration patterns observed were total DP > Mirex > Dec 602 and Dec 604 > Dec 603 > CP in suspended sediments and sediment cores, whereas Mirex was highest in lake trout, followed by Dec 602 and DP. Dec 602 concentrations were 50 to 380 times greater than those of DP in lake trout, indicating Dec 602 has a greater bioaccumulation potential. The estimated biota-sediment accumulation factor (BSAF) for Dec 602 was much greater than for DP in Lake Ontario, and was greater than those calculated for PBDEs, indicating that assessment of some dechlorane compounds is merited if use is ongoing or planned. [ABSTRACT FROM AUTHOR]

Dechlorane (Dec) 602, Dechlorane (Dec) 603, Dechlorane (Dec) 604, and Dechlorane Plus (DP) are flame retardant substitutes for mirex. Dec 602, 603, and 604 were detected in sediment and fish from the Laurentian Great Lakes. Lake Ontario surface sediments had the highest concentrations of Dec 602 and 604 at 6.0 and 4.0 ng/g dry weight, respectively. Temporal analysis of a Lake Ontario sediment core indicates that Dec 602 and 604 trends are similar to DP peaking in the early 1980s. Lake trout and whitefish from Lake Ontario also had the highest concentrations of Dec 602 and 604 at 34 and 1.2 ng/g lipid. Concentrations of Dec 602 were higher than those of DP in all fish samples, indicating that Dec 602 is likely more bioavailable and/or more readily bioaccumulates than DP. Spatial trends for Dec 602 and 604 in sediment and fish indicate that manufacturing plants along the Niagara River upstream of Lake Ontario were important sources of Dec 602 and 604 to the Great Lakes, while Dec 603 in the Great Lakes is likely from atmospheric deposition. The findings of this first report of Dec 602, 603, and 604 in the Laurentian Great Lakes basin suggests further investigation of halogenated norbornene flame retardants in the environment is merited. [ABSTRACT FROM AUTHOR]

The historical occurrence of Dechlorane Plus (DP) and detection of novel compounds structurally related to DP is described in a dated Lake Ontario sediment core. Our core was collected near the mouth of the Niagara River, which is known to be a major source of DP to the lake. Maximum DP concentrations (920 ng g-1, dry weight) were observed between 1976 and 1980, the highest reported to date. Following that time, we observed a dramatic decrease in DP concentration which coincided with the enactment of United States federal and state laws to mitigate free release of chemicals into the Niagara River and installation of an industrial wastewater treatment facility. During the course of our research, four new substances structurally related to DP were also identified. These compounds were thought to arise from the Diels—Alder reactions resulting from impurities present in 1,5-cyclooctadiene, a feedstock used in production of DP. To confirm our hypothesis, Diels—Alder reactions were performed on the individual impurities. Using different stationary-phase capillary gas chromatography columns and high-resolution mass spectrometry, we were able to positively identify some of these novel compounds in the core. Interestingly, we also were able to identify a monoadduct compound, formed by addition of 1 mol of hexachlorocyclopentadiene to 2 mol of 1,3-cyclooctadiene, in lake trout. The concentration of this monoadduct was approximately 2 orders of magnitude greater than that of DP, suggesting that it is more bioaccumulative. [ABSTRACT FROM AUTHOR]