The metabolism of PCBs in experimental animals has been extensively reviewed. Many substrates have been tested, and the PCBs were usually administered by the oral or parenteral routes. In general, these studies showed that the metabolism rate of PCBs depends on the number and position of chlorine atoms on the phenyl ring and on the animal species. In rats, the elimination half-lives of four PCBs with one, two, five, or six chlorines increased as the number of chlorines increased. The decreased excretion rate with increasing chlorination was directly related to the decreased rate of metabolism of the more highly chlorinated congeners. Sheep liver microsomes converted 2,2',5-triCB to at least 5 more polar metabolites within 1 min and at least 10 metabolites by 15 min; however, within the homologous series, 2,2',5,5'-tetraCB and 2,2',4,5,5'-pentaCB were oxidized to only 3 metabolites at rates 7- and 14-fold slower, respectively. Not only does the number of chlorines affect the rate of biotransformation, but the position of the chlorines on the phenyl rings is also critical. This was demonstrated in rats, which excreted four symmetrical hexachlorobiphenyls at different rates depending on the chlorine positions. As the number of unsubstituted meta positions or adjacent unsubstituted carbon atoms increases, the percentage of the dose excreted increases. The major hydroxylated PCB metabolite in rat plasma after administration of 25 mg/kg Aroclor 1254 in peanut oil by gavage is 4-hydroxy-2,3,3',4',5-pentaCB. From days 1 to 14 after exposure, this metabolite is found at concentrations 7-10 times the concentration of the major PCB 153.
The metabolism of PCBs following oral and parenteral administration in animals has been extensively studied and reviewed, but studies in animals following inhalation or dermal exposure are lacking. Information on metabolism of PCBs in humans is limited to occupationally exposed individuals whose intake is derived mainly from inhalation and dermal exposure. In general, metabolism of PCBs depends on the number and position of the chlorine atoms on the phenyl ring of the constituent congeners (i.e., congener profile of the PCB mixture) and animal species. Although only limited data are available on metabolism of PCBs following inhalation exposure, there is no reason to suspect that PCBs are metabolized differently by this route. Data exist on the in vitro hepatic metabolism and in vivo metabolic clearance of 2,2',3,3',6,6'-hexachlorobiphenyl and 4,4'-dichlorobiphenyl congeners in humans, monkeys, dogs and rats. The hexachlorobiphenyl congener is a constituent of Aroclor 1254. For each congener, the Vmax values for metabolism in the monkey, dog and rat are consistent with the respective metabolic clearance values found in vivo. Thus, the kinetic constants for PCB metabolism obtained from the dog, monkey and rat hepatic microsomal preparations were good predictors of in vivo metabolism and clearance for these congeners. In investigations directed at determining which species most accurately predicts the metabolism and disposition of PCBs in humans, the in vitro metabolism of these congeners was also studied using human liver microsomes. Available data suggest that metabolism of PCBs in humans would most closely resemble that of the monkey and rat. For example, the in vitro apparent Km and Vmax are comparable between humans and monkeys. These studies show consistency between the in vitro and in vivo findings and collectively indicate that metabolism of the two congeners is similar in monkeys and humans.
... To study the possible role of non-parenchymal cells in the metabolism of xenobiotics, populations of non-parenchymal and parenchymal cells (PC) were prepared from rats and various xenobiotic metabolizing enzyme activites investigated. The specific activity of every enzyme studied (ethoxyresorufin deethylase, benzphetamine demethylase, glutathione transferase, UDP glucuronosyltransferase, and microsomal epoxide hydrolase) was 12 to 1000% higher in the parenchymal than in the non-parenchymal populations ... The non-parenchymal cells demonstrated a more dramatic induction of enzyme activities in Aroclor 1254-pretreated animals than did the parenchymal. Moreover, despite the generally lower enzyme activities, even after induction, the non-parenchymal were damaged by biologically inert xenobiotics which can be metabolized to reactive intermediates ...
The distribution of aminopyrine N-demethylase (APND), ethoxyresorufin O-deethylase (ERRD), epoxide hydrolase (EH), and glutathione transferase (GST) activities in parenchymal (PC) and non-parenchymal (NPC) cell populations of control and Aroclor 1254-treated C57BL/6N and DBA/2N mice was determined. Furthermore, the metabolism of benzo(a)pyrene (BP) in parenchymal and non-parenchymal of both Aroclor 1254-treated mice strains was examined ... In non-parenchymal cells of both strains a low ratio of oxidative (epoxide aminopyrine N-demethylase and ethoxyresorufin O-deethylase) post-oxidative (epoxide hydrolase and glutathione transferase) enzyme activities was observed. ... Treatment with Aroclor 1254 enhanced all the enzyme activities measured in parenchymal and non-parenchymal of both mice strains with the exception of ethoxyresorufin O-deethylase in parenchymal and non-parenchymal of DBA/2N mice. This is due to the fact that the induction process of ethoxyresorufin O-deethylase by aromatic and halogenated aromatic compounds such as Aroclor 1254 depends upon the presence of a cytosolic receptor with a high affinity for this type of inducers and the DBA/2N mice have a very poor affinity receptor. After incubating benzo(a)pyrene with parenchymal or non-parenchymal or Aroclor 1254-treated C57BL/6N mice significant amounts of 9,10-dihydrodiol, 4,5-dihydrodiol, 7,8-dihydrodiol, quinone, 9-hydroxy, and 3-hydroxy derivatives of benzo(a)pyrene were detected.
Differences in aryl-hydrocarbon-hydroxylase (AHH) inducibility by sodium phenobarbital or Aroclor 1254 were investigated in four strains of Drosophila-melanogaster. Berlin-K, D-melanogaster-Oregon-K, D-melanogaster-Haag-79, and D-melanogaster-Hikone-R adults (2 days old) were transferred to vials containing labeled cytochrome P-450 inducer. Concentrations of the inducers were 6.67 ug 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD), 0.2 mg benzo(a)anthracene (BA), 0.15 mg Aroclor 1254, and 3.0 mg sodium-phenobarbital. After 3 days of feeding, two males and two females were combined and homogenized for the fluorometric assay of aryl-hydrocarbon-hydroxylase. Cytosolic samplers from D melanogaster adults were incubated with labeled 2,3,7,8-tetrachlorodibenzo-p-dioxin or benzo(a)anthracene for 1 hr at 4 °C. High performance liquid chromatography was performed for the Ah receptor. Phenobarbital induced aryl-hydrocarbon-hydroxylase activity more than 10 fold in D-melanogaster-Berlin-K and D-melanogaster-Oregon-K and about 2 fold in D-melanogaster-Haag-79 and D-melanogaster-Hikone-R. Aroclor 1254 induced aryl-hydrocarbon-hydroxylase activity 2 to 4 fold in all the strains except D-melanogaster-Hikone-R. There was no significant aryl-hydrocarbon-hydroxylase induction by 2,3,7,8-tetrachlorodibenzo-p-dioxin or benzo(a)anthracene in any of the four strains. In the presence of a 100 fold excess of nonlabeled benzo(a)anthracene competitor, no saturable high affinity low capacity benzo(a)anthracene binding moiety could be demonstrated in any of the four strains. High affinity 2,3,7,8-tetrachlorodibenzo-p-dioxin binding sites were observed by an excess of nonlabeled 2,3,7,8-tetrachlorodibenzo-p-dioxin ...
The mechanism of action varies with the specific PCB. Dioxin-like PCBs bind to the aryl hydrocarbon receptor, which disrupts cell function by altering the transcription of genes, mainly be inducing the expression of hepatic Phase I and Phase II enzymes, especially of the cytochrome P450 family. Most of the toxic effects of PCBs are believed to be results of Ah receptor binding. Other PBCs are believed to interfere with calcium channels and/or change brain dopamine levels. PCBs can also cause endocrine disurption by altering the production of thyroid hormones and binding to estrogen receptors, which can stimulate the growth of certain cancer cells and produce other estrogenic effects, such as reproductive dysfunction. They will bioaccumulate by binding to receptor proteins such as uteroglobin. (A3, A4, A30, A66)
来源:Toxin and Toxin Target Database (T3DB)
毒理性
致癌性证据
分类：B2；可能的人类致癌物。分类依据：1996年的一项研究发现，暴露于Aroclors 1260、1254、1242和1016的雌性大鼠以及暴露于1260的雄性大鼠出现了肝脏肿瘤。这些混合物包含有重叠的同类物群，共同涵盖了在环境混合物中最常发现的同类物范围。早期的研究发现，摄入Aroclor 1260或Clophen A 60的大鼠中，肝脏肿瘤的发生率很高，具有统计学上的显著性。机制研究开始识别出几种具有二噁英样活性的同类物，它们可能通过不同的作用方式促进肿瘤。多氯联苯通过摄入、吸入和皮肤接触被吸收，之后它们通过循环系统以类似的方式传输。这为预期不同环境暴露途径可能产生类似的内部效果提供了合理的依据。关于相对吸收率的信息表明，不同暴露途径之间的毒性差异很小。人类研究正在更新中；目前可用的证据不充分，但具有启发性。人类致癌性数据：不充分。动物致癌性数据：充分。/多氯联苯/ /基于先前的分类系统/
CLASSIFICATION: B2; probable human carcinogen. BASIS FOR CLASSIFICATION: A 1996 study found liver tumors in female rats exposed to Aroclors 1260, 1254, 1242 and 1016 and in male rats exposed to 1260. These mixtures contain overlapping groups of congeners that, together, span the range of congeners most often found in environmental mixtures. Earlier studies found high, statistically significant incidences of liver tumors in rats ingesting Aroclor 1260 or Clophen A 60. Mechanistic studies are beginning to identify several congeners that have dioxin-like activity and may promote tumors by different modes of action. PCBs are absorbed through ingestion, inhalation, and dermal exposure, after which they are transported similarly through the circulation. This provides a reasonable basis for expecting similar internal effects from different routes of environmental exposure. Information on relative absorption rates suggests that differences in toxicity across exposure routes are small. The human studies are being updated; currently available evidence is inadequate, but suggestive. HUMAN CARCINOGENICITY DATA: Inadequate. ANIMAL CARCINOGENICITY DATA: Sufficient. /Polychlorinated Biphenyls/ /Based on former classification system/
来源:Hazardous Substances Data Bank (HSDB)
毒理性
致癌性证据
A3：已确认的动物致癌物，对人类的相关性未知。/氯二苯（含氯量54%）/
A3: Confirmed animal carcinogen with unknown relevance to humans. /Chlorodiphenyl (54 percent chlorine)/
来源:Hazardous Substances Data Bank (HSDB)
毒理性
致癌性证据
多氯联苯（PCBs）：合理预期为人类致癌物。/多氯联苯（PCBs）/
Polychlorinated Biphenyls (PCBs): reasonably anticipated to be human carcinogens. /Polychlorinated Biphenyls (PCBs)/
Limited specific information is available on the oral absorption of Aroclor 1254. Pregnant ferrets that ingested a single oral dose of Aroclor 1254 (approx 0.06 mg/kg) absorbed approximately 85% of the initial amount. Studies predominately of individual chlorobiphenyl congeners indicate, in general, that PCBs are readily and extensively absorbed by animals. These studies have found oral absorption efficiency on the order of 75 to > 90% in rats, mice and monkeys. A study of a non-Aroclor 54% chlorine PCB mixture prepared by the investigators provides direct evidence of absorption of PCBs in humans after oral exposure, and indirect evidence of oral absorption of PCBs by humans is available from studies of ingestion of contaminated fish by the general population. There are no quantitative data regarding inhalation absorption of PCBs in humans but studies of workers exposed suggest that PCBs are well absorbed by the inhalation and dermal routes. PCBs distribute preferentially to adipose tissue and concentrate in human breast milk due to its high fat content.
When Aroclor 1254 was fed to pheasants either as a single dose of 50 mg or as 17 weekly doses of 12.5 or 50 mg, up to 82% was absorbed from the gastrointestinal tract and up to 50 mg/kg (wet weight) were found in their eggs.
In Sherman rats given doses of 10 or 50 mg/kg body weight/day Aroclor 1254 on days 7-15 of pregnancy, the average PCB concentrations in fetuses taken by Caesarean section on day 20 of pregnancy were 0.63 and 1.38 mg/kg, resp, compared with less than 0.12 mg/kg in controls.
Physical, spectral and chromatographic properties of all 209 individual PCB congeners
摘要：
Physical, spectral and chromatographic data for all 209 individual PCB congeners is presented. The individual congeners were synthesized and then isolated and purified. Recent emphasis on the source of the toxicity of commercial PCB formulations has increased the need for a complete set of the PCB congeners. Through the use of two capillary GC columns: 40% octadecyl/ 15% phenyl methyl siloxane and 50% phenyl methyl siloxane, it was possible to separate 201 PCB congeners with only four unresolved pairs. The data compiled in this study for all 209 congeners will aid in the identification of selected individual components of these environmental pollutants. The use of this data also presents the opportunity for the improved quantification of the commercial PCB formulations.
Instruments for detecting low-molecular weight substance
申请人：Mizukami Haruki
公开号：US20050148097A1
公开（公告）日：2005-07-07
To provide the following instruments 1 and 2 as a low-molecular-weight substance detection instrument employing immunochromatography capable of detecting conveniently and sensitively detecting a low-molecular weight substance such as an environmental pollutant (e.g., a dioxin), as a target substance contained in a test sample: 1. an instrument, which comprises 1) a test sample application section with which a test sample is brought into contact; 2) a label product reaction section containing a label product containing, as a portion thereof, an antibody capable of binding to a target substance contained in the test sample, the label product being not bound to the reaction section; 3) an unbound label product capturing section containing an element capable of capturing the label product which is not bound to the target substance, the element being bound to the capturing section; and 4) a detection section containing a detection element which, when coming into contact with the target substance bound to the label product, causes a visually observable change, and 2. an instrument wherein a test sample is reacted with a labeled antibody containing, as a portion thereof, an antibody capable of binding to a target substance contained in the test sample, and the resultant reaction product is employed for detecting the target substance contained in the test sample.
Fortified epoxy resin compositions and process for the preparation thereof
申请人：Canadian Patents and Development Limited
Société Canadienne des Brevets et
d'Exploitation Limitée
公开号：EP0103392A1
公开（公告）日：1984-03-21
Heat curable epoxy resin compositions comprising a resin-forming polyepoxide and an amine curing agent are fortified (i. e. given increased strength and modulus but without consequent brittleness) by incorporating into the resin mix prior to curing up to 40 parts by weight per hundred parts of resin of a fortifying agent which is the reaction product of an aromatic amine, e. g. aniline, with a mono- or di-epoxide, the fortifier thus obtained optionally further being reacted with an isocyanate or nitrile prior to incorporation into the resin mix.
Halogen-containing organic compounds e.g. polychlorinated biphenyls (PCB's) are destroyed by being contacted in gaseous form in the absence of oxygen to AI, Mg, Si, Ti or Be having a high specific area, and an area of 0.1 - 65 m2 of metal surface per gram of organic compound to be destroyed, at temperatures of 450 - 650°C for times up to 50 seconds. The PCB's are generally entrained in an inert carrier gas. The method is suitable for continuous operation. When the metal becomes deactivated by reason of a carbonaceous deposit on the surface, it can be regenerated, e.g. by treatment with sodium hydroxide solution.
Fortifier or strengthener for anhydridecured epoxy resins and anhydride curable epoxy resins containing it
申请人：NATIONAL RESEARCH COUNCIL OF CANADA
公开号：EP0283199A2
公开（公告）日：1988-09-21
An anhydride-cured epoxy resin (epoxy resin plus anhydride curing agent plus catalyst) may be fortified (i.e. increased in strength and modulus without being made brittle) by the addition of a fortifying agent comprising a mixture of a carboxylic acid and the reaction product of a carboxylic acid anhydride and a substituted aromatic amine.
Crystalline wholly aromatic polyester, process for its production, resin composition containing it, and articles from the resin composition
申请人：TEIJIN LIMITED
公开号：EP0472366A2
公开（公告）日：1992-02-26
A crystalline wholly aromatic polyester :
(1) which consists essentially of
a polymer unit A of the formula
a polymer unit B of the formula
and
a polymer unit C of the formula
these polymer units being bonded together to form an ester having a linkage (-COO-),
(2) which has a melting point lower than that of the known crystalline wholly aromatic polyester having same composition ; a process for the production of a crystalline wholly aromatic polyester, using a phenol or phenol derivative as a reaction medium ; a reinforced resin composition comprising the above wholly aromatic polyester ; and a shaped or molded article formed from the above resin composition.
一种全芳香族结晶聚酯：
(1) 主要由以下成分组成
式中的聚合物单元 A
式中的聚合物单元 B
和
式中的聚合物单元 C
这些聚合物单元结合在一起，形成具有连接（-COO-）的酯、
(2) 其熔点低于具有相同组成的已知结晶全芳香族聚酯的熔点；一种使用苯酚或苯酚衍生物作为反应介质生产结晶全芳香族聚酯的工艺；一种包含上述全芳香族聚酯的增强树脂组合物；以及一种由上述树脂组合物形成的成型品或模塑品。
