2,2',4,4'-テトラクロロジフェニルエーテル

Bis(2,4-dichlorophenyl)ether was detected in ringed seals (Phoca hispida saimensis) from Lake Saimaa and one seal (Phoca sibirica) from Lake Baikal, Finland at concentrations of 6 to 11 ng/g lipid weight; seals were collected in 1988 and 1992, respectively(1). Bis(2,4-dichlorophenyl)ether was not detected in white-tailed eagle (Hailaetus albicilla) from the Baltic(2).

Using a structure estimation method based on molecular connectivity indices(1), the Koc of bis(2,4-dichlorophenyl)ether can be estimated to be 2.9X10+4(SRC). According to a classification scheme(2), this estimated Koc value suggests that bis(2,4-dichlorophenyl)ether is expected to be immobile in soil.

Bis(2,4-dichlorophenyl)ether was detected in carp (Carpiodes carpio) at 24 to 170 pg/g and in pike (Esox lucius) at 30 to 137 pg/g; fish were collected from Whitby Harbour, on Lake Ontario(1). Bis(2,4-dichlorophenyl)ether was detected in lake trout (Salvelinus namaycush) collected in the fall of 1992 from Lake Ontario and Lake Huron at a trace to 5.2 and not detected to 0.4 ug/kg(2). In the same survey, trout from Lake Superior did not contain bis(2,4-dichlorophenyl)ether(2). Bis(2,4-dichlorophenyl)ether was detected in walleye (Stizostedion vitreum) from Lake Erie at not detected to 0.4 ug/kg(2). Bis(2,4-dichlorophenyl)ether was not detected (detection limit <5 pg/g) in salmon caught in the Central Gulf of Bothnia in 1986 and in the Baltic Sea near Gothland in 1986, but was detected in salmon caught in the Gulf of Finland in 1987 at 0.005 to 0.013 ng/g(3). Bis(2,4-dichlorophenyl)ether was not detected (detection limit <5 pg/g) in cod liver fat; cod were caught at the Arctic Coast of Norway in 1987 and 1988(3). Bis(2,4-dichlorophenyl)ether was detected in pike and lake bream sampled from the Kymijoki River, Finland at 9-12 and 10 pg/g fresh weight, respectively; sample dates were not provided(4). Pike, sampled from the Kymijoki River, Finland were found to contain <7 ng/g lipid weight of bis(2,4-dichlorophenyl)ether, samples were collected in 1993(5).

Tetra-to decachlorodiphenyl ether (CDPE) concentrations were measured in take trout and walleye, fish that represent the higher trophic levels in the North American Great Lakes. GC-MS analyses indicated the mean total CDPE concentrations were 4, 16, 57, and 126 ug/kg in whole fish from Lakes Superior, Huron, Erie, and Ontario, respectively. The number of known and unidentified congeners detected above the 0.4-mug/kg detection limit ranged from six to 24 congeners among the lakes, and this number increased with the total concentration of CDPEs. The Cl6 homologue represented 46 to 61% of total CDPEs in Lakes Huron, Erie, and Ontario, and the Cl5, Cl6, and Cl7 homologues represented 78 to 93% of total CDPE concentrations.

The presence of 26 congeners of polychlorinated diphenyl ethers (PCDEs) was investigated in salmon from three locations in Finland. In addition to salmon, one chlorophenol wood preservative (Ky-5) and one fly ash sample were analyzed for PCDEs. Concentrations of PCDE congeners in salmon muscle measured by high resolution gas chromatography/low resolution mass spectrometry ranged from <0.02 to 2.4 ng/g fresh weight. The major components of tetra- to octachlorinated PCDEs in salmon were one TeCDE (22'44'-), two PeCDEs (22'44'5- and 23'44'5-) and three HxCDEs (22'44'56'-, 22'44'55'- and 22'344'5-). The Baltic salmon caught from the Simojoki River had higher levels of PCDEs than the Atlantic salmon from the Tenojoki River or salmon from Lake Saimaa in South-Finland. Same PCDE congeners which were abundant in the wood preservative were also detected in salmon, whereas PCDE congeners in the fly ash were different from those in salmon or in Ky-5.

The BCF in rainbow trout (Salmo gairdneri) has been reported to be 12,400(1). According to a classification scheme(2), this BCF suggests bioconcentration in aquatic organisms is very high(SRC).

Biomagnification factors (BMF) were calculated as ratios for selected portions of the food web of Whitby Harbour, Lake Ontario, Canada(1). Samples were collected over a three year period from 1994 to 1996(1).[Table#4221]

The Henry's Law constant for bis(2,4-dichlorophenyl)ether is estimated as 3.5X10-5 atm-cu m/mole(SRC) using a fragment constant estimation method(1). This Henry's Law constant indicates that bis(2,4-dichlorophenyl)ether is expected to volatilize from water surfaces(2). Based on this Henry's Law constant, the volatilization half-life from a model river (1 m deep, flowing 1 m/sec, wind velocity of 3 m/sec)(2) is estimated as 2 days(SRC). The volatilization half-life from a model lake (1 m deep, flowing 0.05 m/sec, wind velocity of 0.5 m/sec)(2) is estimated as 20 days(SRC). However, volatilization from water surfaces is expected to be attenuated by adsorption to suspended solids and sediment in the water column(SRC). The estimated volatilization half-life from a model pond is 75 years if adsorption is considered(3). Bis(2,4-dichlorophenyl)ether's Henry's Law constant indicates that volatilization from moist soil surfaces may occur(SRC). Bis(2,4-dichlorophenyl)ether is not expected to volatilize from dry soil surfaces(SRC) based upon an estimated vapor pressure of 9.9X10-6 mm Hg(SRC), determined from a fragment constant method(4).

/ALTERNATIVE and IN VITRO TESTS/ Polychlorinated diphenyl ethers (PCDEs) are structurally similar to polychlorinated biphenyls (PCBs), and some PCDE congeners have been reported to cause toxic responses similar to those caused by some of the non-ortho-substituted PCBs, which are mediated by the aryl hydrocarbon receptor (AhR). Twenty-nine PCDEs /including bis(2,4-dichlorophenyl) ether/ were tested for their potency as AhR agonists relative to 2,3,7,8-tetrachlorodibenzo-p-dioxin (2,3,7,8-TCDD) by measuring their ability to induce the cytochrome P-450 1A1-associated enzyme activity, ethoxyresorufin-O-deethylase (EROD), in the H4IIE rat hepatoma cell bioassay. All PCDE congeners tested were found to be inactive as EROD inducers except for PCDE 156, which was a weak EROD inducer with a 2,3,7,8-TCDD equivalency factor of about 1.2 /The authors/ determined that small amounts of polychlorinated dibenzofurans (PCDFs) that occurred as impurities in the PCDE preparations were the cause of the apparent EROD induction initially measured in our experiments...