Disease relevance of PCB 128

• Thus, within the Sprague-Dawley rat group exposed to a diet with relatively high concentrations of Aroclor 1260 for 2 years a hepatocarcinogenic effect manifested by formation of slowly growing hepatocellular carcinomas was produced [1].
• Treatment with Aroclor 1260 at dosages ranging from 0.5 to 50 mg/kg/day had no effect on body weight, but liver weight was increased significantly in rats treated with the two highest dosages [2].
• In response to weight loss, significant increases of all organochlorines investigated were observed in men, whereas only p,p'-DDE, Aroclor 1260, PCBs 153 and 180 significantly rose in women [3].
• Subchronic toxicity of 2,2',3,3',4,4'-hexachlorobiphenyl in rats [4].

High impact information on PCB 128

• Analysis of the rodent carcinogenicity data for Aroclor 1260 using the TEF approach suggests that this response is primarily Ah-receptor-independent [5].
• Triplicate cultures of the eighth transfer without sediment dechlorinated 76% of the hexa- through nonachlorobiphenyls in Aroclor 1260 (250 mug/ml) to tri- through pentachlorobiphenyls in 110 days [6].
• Following 4 months of anaerobic treatment with an enrichment culture, all of the major components in Aroclor 1260 were completely or partially transformed to less chlorinated PCB congeners [7].
• The hepatic tumor promoting activity of the planar 0-1 ortho ( approximately 9.7% w/w) and the nonplanar 2-4 ortho ( approximately 90.3% w/w) fraction of the commercial PCB mixture Aroclor 1260 was studied using a medium-term two-stage initiation/promotion bioassay in female Sprague-Dawley rats [8].
• To evaluate the effect of exposure to an environmentally relevant polychlorinated biphenyl mixture, adult male rats were treated with Aroclor 1260 for 7 days and levels of several cytochrome P450 (CYP) enzymes were measured in liver microsomes prepared 3 days after the last dose [2].

Chemical compound and disease context of PCB 128

• The commercial polychlorinated biphenyl (PCB) formulation Aroclor 1260 (4 mg/kg body weight), technical grade dichlorodiphenyltrichloroethane (DDT; 3 mg) and Lindane (gamma-hexachlorocyclohexane; 0.8 mg) were administered orally, either separately or in combination, to sexually mature female rabbits three times per week for 12-15 weeks [9].
• In men, relationships between changes in plasma HCB, Aroclor 1260, and PCB-153 concentrations and those in fasting insulin levels in response to weight loss remained significantly correlated after correction for fat mass loss (-.46 < partial r < -.51, P values ranging from.05 to.07) [10].

Biological context of PCB 128

• However, the extent of apoptosis resulted greater for Aroclor 1248 than for Aroclor 1260 [11].
• The addition of Aroclor 1260 had a significant impact on abundance, biomass, and cell size of autotrophic and heterotrophic picoplankton, and reduced significantly bacterial secondary production [12].
• An analysis of individual PCB congener signatures in plant site background samples using principal components analysis (PCA) revealed that the past use of specific commercial PCB formulations at these sites, such as Aroclor 1260 on the east coast, is reflected in the PCB congener signature present in the plants [13].
• We determined for PCB 128, when administered in a diet to Sprague-Dawley rats, the no observable adverse effect level (NOAEL) is < 0.5 ppm [14].
• Effect of polychlorinated biphenyl (Aroclor 1260) on histology of kidney and thyroid of rats [15].

Anatomical context of PCB 128

• Aroclor 1260 concentrations ranged from 18 to 28 ppm with the highest levels found in the hippocampus [16].
• 1. Pigeons were injected with a single dose of commercial PCB mixtures (Aroclor 1248 plus Aroclor 1260), killed 120 h later and the abundance of individual PCBs was determined in adipose tissue, gonads, liver, brain, kidney, heart, muscle and blood [17].
• Cord blood PCB levels (as Aroclor 1260) averaged 1.16 (+/-2.42) microg/l for Inuit participants, which was 3.3-4 fold higher than the other ethnic groups [18].
• A rapid method for determination of Aroclor 1260 in cattle adipose tissue [19].
• Gross histological alteration in kidney and thyroid structures were observed in male Wistar rats fed polychlorinated biphenyls (PCBs; Aroclor 1260) at 50 and 100 ppm level in normal commercial diet for 120 days [15].

Associations of PCB 128 with other chemical compounds

• Ethoxyresorufin O-deethylase activity and CYP1A1 protein levels displayed linear dose-dependent increases, but the hepatic CYP1A1 content did not exceed 10% that of CYP2B1 at all dosages of Aroclor 1260 [2].
• The time course studies also revealed that in the first 3 days of feeding, significant increases in CYP1A1 were found in intestine (betaNF: 320% and Aroclor-1260: 290%), followed by liver (betaNF: 144%, Aroclor-1260: 123% and Aroclor-1254: 110%) [20].
• Residues of DDT (mainly as DDE), trans-nonachlor, dieldrin, Aroclor 1260, mirex, and petroleum hydrocarbons were common in fish from the lower Savannah River, but concentrations were below those warranting environmental concern [21].
• Based on our previous work, PCB 128 is estimated to be equally toxic as PCB 153, another di-ortho substituted PCB congener [22].

Gene context of PCB 128

• Dopamine transporter (DAT) levels were decreased at all time points in Aroclor 1016 treated animals, and on Days 1 and 7 in Aroclor 1260 treated animals [23].
• Differential expression of CYP1A1 mRNA in gill, intestine and liver of tilapia fed with PCB Aroclor-1254 and Aroclor-1260 spiked food [20].
• Concentrations of DDT, DDE, DDD, Aroclor 1254, and Aroclor 1260 were found at concentrations below 0.4 ppm for 13 of 14 samples [24].

Analytical, diagnostic and therapeutic context of PCB 128

• A separate time-course study showed that induction of CYP2B, but not of CYP1A, enzymes persisted for at least 48 days after treatment with Aroclor 1260 at 10 mg/kg/day [2].
• A radioimmunoassay was developed capable of determining Aroclor 1260 in milk at levels of from 20 to 80 ppb and in blood from 2 to 16 ppb [25].
• An analytical method has been developed that uses electron capture/gas-liquid chromatography to determine Mirex in serum containing polychlorinated biphenyls (PCBs) (Aroclor 1260) [26].

References