Polychlorinated biphenyls Section

Aside from the actions already initiated by EPA under Section 6 to restrict exposures to polychlorinated biphenyls and to chlorofluorocarbons in certain uses, no other actions have been taken against specific chemical substances, nor has an imminent hazard been identified for appropriate action. Less than a dozen proposed orders have been issued under Section 5(e) requesting further information to assess the risks of as many new substances. Perhaps 80 informal requests for further information on such substances have been made and satisfied voluntarily. Testing programs for a substantial number of existing substances have been started and more are planned. In addition, of course, the monumental task of creating an inventory of some 55,000 existing chemicals was completed. 

Impacts directly attributable to TSCA regulations include several proposed and final regulations directed at specific chemical substances under section 6—polychlorinated biphenyls (PCBs), dioxin, chlorofluorocarbons (CFCs), and asbestos—and orders issued under section 5(e). 

Giesy JP, Verbrugge DA, Othout RA, et al. 1994. Contaminants in fishes from Great Lake influenced sections and above dams of three Michigan rivers. I Concentrations of organochlorine insecticides, polychlorinated biphenyls, dioxin equivalents, and mercury. Arch Environ Contain Toxicol 27 202-212. 

Polychlorinated biphenyls (PCBs) are a family of compounds, manufactured in the United States from 1930-1975, which were used in a number of discard applications and extensively as an electrical insulating fluid (see Chap. 1). Environmental concerns have led to strict controls on the use of PCBs and standards for cleanup of PCB discharges. One of the purposes of this section is to present information on the chemical and physical characteristics of these compounds. Based on this, the mechanisms of their movement in the surface/subsurface environment can be explained. 

Polychlorinated biphenyls (PCBs) were manufactured by catalytic chlorination of biphenyl to produce complex mixtures, each containing 60-90 different PCB molecular species or congeners (see Chaps. 1 and 4). In the United States, PCB mixtures were manufactured by Monsanto under the trade name Aroclor and were widely used as dielectric fluids in capacitors and transformers from 1929 to 1978. PCBs are widespread contaminants of aquatic sediments and continue to be a focus of environmental concern because they tend to accumulate in biota and are potentially toxic. The following sections show the most effective bioremediation techniques applied to various PCB contaminated environments ... 

For many, familiarity with the TSCA generally stems from its specific reference to polychlorinated biphenyls, which raise a vivid, deadly characterization of the harm caused by them. But the TSCA is not a statute that deals with a single chemical or chemical mixture or product. In fact, under the TSCA, the EPA is authorized to institute testing programs for various chemical substances that may enter the enviromnent. Under the TSCA s broad authorization, data on the production and use of various chemical substances and mixtures may be obtained to protect public health and the environment from the effects of harmful chemicals. In actuality, the TSCA supplements the appropriate sections dealing with toxic substances in other federal stamtes, such as the Clean Water Act (Section 307) and the Occupational Safety and Health Act (Section 6). 

Polychlorinated biphenyls (PCBs), CFCs, petroleum products, and dioxin are major toxic contaminants in air (Section 3.3.2), soil (Section 3.5.3), and also in water. The readers are referred to Sections 3.3.2 and 3.5.3 for details about PCB characteristics, health effects, treatment technologies, and so on. For water quality management, they have been included in the list of the USEPA priority pollutants [86]. 

It should be realized that with the exception of a few groups of chemicals (such as some organophosphorous and carbamate pesticides as well as some polychlorinated dibenzo-p-dioxins (PCDDs), polychlorinated dibenzofurans (PCDFs), and polychlorinated biphenyls (PCBs), precise mechanistic information on their toxic effects are scarce. In realizing that the exact molecular mechanism is not known for most chemicals the term mode of action is used to describe toxicides that appear to be similar albeit the mechanism is not known in detail, see also Section 4.2.6. For several groups of endocrine disrupters this terminology seems appropriate. 

It would lie far beyond the aim of this chapter to introduce the state-of-the art concepts that have been developed to quantify the influence of colloids on transport and reaction of chemicals in an aquifer. Instead, a few effects will be discussed on a purely qualitative level. In general, the presence of colloidal particles, like dissolved organic matter (DOM), enhances the transport of chemicals in groundwater. Figure 25.8 gives a conceptual view of the relevant interaction mechanisms of colloids in saturated porous media. A simple model consists of just three phases, the dissolved (aqueous) phase, the colloid (carrier) phase, and the solid matrix (stationary) phase. The distribution of a chemical between the phases can be, as first step, described by an equilibrium relation as introduced in Section 23.2 to discuss the effect of colloids on the fate of polychlorinated biphenyls (PCBs) in Lake Superior (see Table 23.5). 

The simplex approach to SFC optimization has proven to be extremely helpful with real samples as well as synthetic mixtures. In recent work with Arochlor 1254 (Crow and Foley, manuscript in preparation), a mixture of polychlorinated biphenyls (PCBs), the number of resolved peaks increased from 19 to 28 in going from vertex 1 to vertex 21 (optimum). Resolution was improved sufficiently that baseline resolution of most if not all compounds could have been obtained by transferring the optimized method to a longer column as described earlier in the section on Minimizing the Time Required for Optimization. 

Polychlorinated biphenyls (PCBs section 1.2) and dioxins have been most widely studied in this category. PCBs were used in a wide variety of industrial applications, for example as dielectrics in transformers. But they are very persistent contaminants, both in the general environment and in human fat. In theory the routes of entry into food are ... 

Another notable class of persistent organohalide compounds is the polychlorinated biphenyl (PCB) class, discussed in Section 16.4. Widely used in industrial applications, these compounds have become widespread and persistent environmental pollutants. The compound 2,3,7,8-tetrachlo-rodibenzo-p-dioxin (TCDD), commonly known as dioxin, discussed in Section 16.6, is an extremely persistent manufacturing by-product that has caused significant environmental problems. 

Although this public health statement will focus on CDDs, it is important to note that CDDs are found in the environment together with other structurally related chlorinated chemicals, such as chlorinated dibenzofurans (CDFs) and polychlorinated biphenyls (PCBs). Therefore, people are generally exposed to mixtures of CDDs and other classes of toxicologically and structurally similar compounds. 2,3,7,8-TCDD is one of the most toxic and extensively studied of the CDDs and serves as a prototype for the toxicologically relevant or dioxin-like CDDs. Based on results from animal studies, scientists have learned that they can express the toxicity of dioxin-like CDDs as a fraction of the toxicity attributed to 2,3,7,8-TCDD. For example, the toxicity of dioxin-like CDDs can be half or one tenth or any fraction of that of 2,3,7,8-TCDD. Scientists call that fraction a Toxic Equivalent Factor (TEF). More information on TEFs can be found in Section 2.5. 

The most relevant problem originating from MSW incineration is flue gas treatment, since untreated incineration flue gas can contain large amounts of macropollutants (e.g., CO, S02, HC1, NOx, particulates) andmicropollutants (e.g., PAHs, mercury compounds, polychlorinated biphenyls, dioxins, furans). The necessity of reducing polluting emissions to levels compatible with existing regulations dictates the adoption of rather sophisticated- and expensive flue gas treatment sections in incineration plants. 

The examples that have been discussed in this section, involving some very different kinds of molecules, bring out the fact that toxicity is associated with a certain set of circumstances within a molecule, and not necessarily a particular atom or a certain molecular type. Chlorine is not intrinsically an evil atom, and the polychlorinated biphenyls, for instance, are not necessarily all harmful. Certain specific features, which differ from one class of molecules to another, confer toxicity it is these features that must be identified, and avoided. 

Polychlorinated biphenyls (PCBs) are mixtures of biphenyls with 1 to 10 chlorine atoms per molecule. They are oily fluids with high boiling points, great chemical resistance, and low electrical conductivity, and have been used as plasticizers in polyvinyl polymers, insulators and coolants in transformers and heat exchange fluids. Dioxins and furans (see Section 9.1) are not produced intentionally but are derived from combustion processes of chlorinated aromatic hydrocarbons, pesticides and chlorinated solvents. 

What isotope pattern would be observed for the molecular ion of 4,4 -dichlorobiphenyl, a polychlorinated biphenyl (PCB) that is a widespread environmental pollutant (Section 3.4) ... 

Figure 3.17 Birefringence as a function of the eigenvalue of the velocity gradient tensor, G, for planar flows generated in a four-roll mill, for dilute solutions of polystyrenes of three different molecular weights in polychlorinated biphenyl solvent. Here G is the strain rate and a the flow type parameter. For planar extension, a — 1 and G = is the extension rate for simple shear, a = 0 and G = y is the shear rate. The different symbols correspond to a values of 1.0 (0)> 0.8 (A), 0.5 (-1-), and 0.25 (diamonds). The curves are theoretical predictions from the FENE dumbbell model, including conformation-dependent drag (discussed in Section 3.6.2.2.2). (From Fuller and Leal 1980, reprinted with permission from Steinkopff Publishers.)...

A developing area of research has been endocrine disruption. Apparently, a wide variety of materials can interfere with or mimic endocrine function. Estrogen mimics and the possible modes of action of these materials are discussed with particular emphasis on dioxins and the polychlorinated biphenyls (PCBs). Other classes of compounds and modes of action are also summarized in this section. 

Section 104(i)(5) of CERCLA, as amended, directs the Administrator of ATSDR (in consultation with the Administrator of ERA and agencies and programs of the Public Health Service) to assess whether adequate information on the health effects of polychlorinated biphenyls is available. Where adequate information is not available, ATSDR, in conjunction with the National Toxicology Program (NTP), is required to assure the initiation of a program of research designed to determine the health effects (and techniques for developing methods to determine such health effects) of polychlorinated biphenyls. 

EPA. 1978c. U.S. Environmental Protection Agency. Support document Draft voluntary environmental impact statement for polychlorinated biphenyls (PCBs) manufacturing, processing, distribution in commerce and use ban regulation (Section 6(e) of TSCA). 

In a later section, we will describe examples where selective extraction has been used to advantage. In one case [6,7], hpid-free-fractions of polychlorinated biphenyls (PCBs) were extracted by SFE from sea gull eggs. An independent liquid-solvent extraction and analysis of the hpid fraction of the eggs indicated a 35 % hy weight fat content, while after the selective extraction (judicious choice of density/temperature conditions at each selective fractionation step) the fat or lipid content was less than 0.1% in the PCB-containing fraction. In a similar experiment, cholesterol has been selectively extracted from cod hver oil samples (an oil-free extract from a sample which contains 99 % hpid or oil). This is shown in Figure 1. The details of this experiment will be discussed in a later section. 

The degradation of polychlorinated biphenyls has been established in a number of organisms enriched with biphenyl as carbon source, for example, Pseudomonas sp. strain LB400 (Bopp 1986), Alcaligenes eutrophus strain H850 (Bedard et al. 1987), and P. pseudoalcaligenes (Furukawa and Arimura 1987). Further details are discussed in Chapter 6, Section 6.5.1.1. 

EPA has authority to require chemical labeling under Section 6 of TSCA. This provision empowers EPA to develop labeling requirements for particular chemicals or chemical classes (Section 6(a)). It also specifically directs EPA to promulgate labeling requirements for polychlorinated biphenyls (PCBs) by prescribed deadlines (Section 6(e)). While EPA has not yet formally exercised its labeling authority except in connection with PCBs, the development of hazard warnings under TSCA for individual chemicals or chemical classes remains a distinct possibility for the future. 

Wastes containing PAHs may be effectively destroyed by various incineration processes as mentioned briefly in the above section. Weber et al. (2001) have studied the mechanisms of formation of polychlorinated diben-zofurans (PCDF), polychlorinated biphenyls (PCB), polychlorinated naphthalenes (PCN) and polychlorinated benzenes (PCBz) from the degradation of PAHs in two types of incinerators, the stoker type- and the fluidized bed incinerators. Their studies have revealed the occurrence of a sequence of steps, such as the cleavage of C-C bond in the PAHs, chlorination at these cleaved positions, further chlorination or oxygen insertion at the ortho positions to the chlorine atoms in the intermediate chlorinated species. A perylene structure in soot is proposed as the basis for the observed PCDF pattern in the fluidized bed incinerators. Polychlorinated dibenzo-dioxins (PCDD) and the polychlorinated... 

Section II Polychlorinated Biphenyls (PCBS) Trichloroethane, Trichloroethylene and Perchloroethylene... 

CFR101-42.404 41CFR101.42.1102 4.6.7 Sale of Certain Hazardous Materials - DOE or DOE contractors shall follow the special sales requirements provided in 41CFR101.42.1102 for certain hazardous materials (e.g., asbestos, polychlorinated biphenyls, controlled substances, etc.) (see Sections 4.8.1 through 4.8.4, below). The holding agency (DOE) shall properly store hazardous items and provide information to ensure that prospective bidders are aware of the hazards, as well as the precautions they should take to protect themselves. 

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