Polychlorinated biphenyls endocrine disruption

UV filters are currently considered as emerging environmental contaminants of increasing concern since most of the commonly used are known to cause endocrine disrupting effects in both aquatic and terrestrial organisms as well as in human skin cells [4]. These compounds bioaccumulate in fish at similar levels to polychlorinated biphenyls (PCBs) and DDT [5, 6]. 

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. 

Smeds, A., Saukko, P., 2001. Identification and quantification of polychlorinated biphenyls and some endocrine disrupting pesticides in human adipose tissue from Finland. Chemosphere 44, 1463-1471. 

A number of compounds have been implicated as endocrine disrupters. They include 2,3,7,8-tetrachlorodibenzo-p-dioxin, polychlorinated biphenyls (PCBs), and some phenolic compounds, including nonylphenol and bisphenol-A ... 

From these inventories and data, it is clear that society is facing an enormous problem of contamination. Many of the polluting compounds that are continuously dispersed are products of industrial activities such as phenols and halogenated phenols, polycyclic aromatic hydrocarbons (PAH s), endocrine disruptive chemicals (EDC), pesticides, dioxins, polychlorinated biphenyls (PCB s), industrial dyes, and other xenobiotics. In this chapter, we critically review the literature information on the enzymatic transformation of these polluting xenobiotics. This work is focused on peroxidases as enzymes able to transform a variety of pollutant compounds with the aim to reduce their toxicity and their environmental impact. 

This phenomenon may be also important for all natural estrogens and endocrine-disrupting chemicals (EDCs) which are weak acids, such as 17 -estra-diol, estriol, ethynylestradiol, diethylstilbestrol, nonylphenol, octylphenol, bisphenol-A (BPA), tetrabromobisphenol-A (TBBA), hydroxy polychlorinated biphenyls, and other compounds with hydroxylated aromatic rings. 

Fig. 9. Relationship between the steady-state bioconcentration factors on a lipid basis (BCFl) of chemicals in different fish species and the n-octanol/water partition coefficient (Kqw) (log/log scale). ( ) Solid circles are chemicals with known endocrine-disrupting properties. Abbreviations of the chemicals p,p -DDT 2,2-bis-(p-chlorophenyl)-l,l,l-trichloroethane. OCDD octachlorodibenzo-p-dioxin. TCDD tetrachlorodibenzo-p-dioxin. HCB hexachloro-benzene. PCA pentachloroanisole. PeCB pentachlorobenzene. MX musk xylene. TeCB tetrachlorobenzene. NP nonylphenol. TCB tetrachlorobenzene. y-HCH y-hexachlorocyclo-hexane (Lindane). PCP pentachlorophenol. DCB dichlorobenzene. BPA bisphenol-A. PCBs polychlorinated biphenyls...

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. 

Soontornchat S, Li M-H, Cooke PS, et al. 1994. Toxicokinetic and toxicodynamic influences on endocrine disruption by polychlorinated biphenyls. Environ Health Perspect 102(6-7) 568-571. 

Aoki Y Polychlorinated biphenyls, polychlorinated dibenzo-p-dioxins, and polychlorinated dibenzofurans as endocrine disrupters—what we have learned from Yusho disease. Environ Res 86 2-11, 2001... 

Polychlorinated biphenyls (PCB) - currently banned compounds - were formerly used in hydraulic fluids, plasticizers, adhesives, fire retardants, and pesticide extenders. These contaminants are persistent in the environment and are present in sediments at the bottom of lakes, rivers, and seas. As they exhibit carcinogenic and endocrine-disrupting activity, they are subject to regulation. For instance, in the United States, the maximum allowed concentration of PCBs in drinking water is 0.5 ng mL [21]. 

With few exceptions (c.g., DES), a causal relationship between exposure to a specific environmental agent and an adverse effect on human health operating via an endocrine disruption mechanism has not been established. Short-term screening studies could be developed and validated in an effort to elucidate the mechanism. Through controlled dose-response studies, it appears that these compounds (e.g., alkyl phenol ethylates and their degradation products, chlorinated dibenzodioxins and difurans, and polychlorinated biphenyls) can induce irreversible induction of male sex characteristics on females (impo-sex), which can lead to sterility and reduced reproductive performance. 

A wide range of organic chemicals (mostly synthetics, including certain additives and plasticisers - snch as phthalates, bisphenol A, and nonylphenols - all used as additives in plastics) are snspected potential ECD agents. The list of ECD also inclndes pesticides (such as DDT, which is banned) and many industrial and consnmer products - such as, liquid soaps, shampoos, conditioners, and hair colours - that contain alkylphenol ethoxylates (APE, which have been replaced by the more expensive, but much safer, alcohol ethoxylates). In addition, there are polychlorinated biphenyls (PCB), dioxins, certain preservatives and metal ions, and even certain treated woods suspected as endocrine disruption agents in hnmans based on (limited) animal stndies, (see Table 2.2). Synthetic oestrogens are the focns of cnrrent concern for ECD there are certain natnral... 

As outlined in Chapter 2, ECD are chemicals that can cause hormonal related diseases and dysfunctions that can be effective even at very low levels (at parts per trillion, levels at which most chemicals have never been tested). ECD became a significant focus of environmental science and medicine in recent years because of its critical importance in heath. A wide range of chemicals, both natural compounds (phytoestrogens) and some synthetic chemicals (including polychlorinated biphenyls (PCB), dioxins, certain preservatives and metal ions, even certain woods) are all suspected of being capable of endocrine disruption in humans. 

In its broadest sense, environmental chemistry might be considered to include the chemistry of everything outside of the synthetic chemist s flask The moment that a chemical substance is released to the environment, its physico-chemical properties may have an enormous impact on ecological systems, including humans. Researchers have identified 51 synthetic chemicals that disrupt the endocrine system. Hormone disrupters include some of the 209 polychlorinated biphenyls (PCBs), and some of the 75 dioxins and 135 furans that have a myriad of documented effects (1). The latter half of the twentieth century has witnessed more synthetic chemical production than any other period in world history. Between 1940 and 1982, the production of synthetic chemicals increased about 350 times. Billions of pounds of synthetic materials were released into the environment during this period. United States production of carbon-based synthetic chemicals topped 435 billion pounds in 1992 or 1600 pounds per capita (2). 

Most wastewater streams contain significant amounts of carcinogenic, toxic, mutagenic, or genotoxic substances in addition to conventional pollutants. These harmful compounds originate from industrial processes and households. Some of these toxic chemicals may also exhibit endocrine-disrupting effects. Therefore, organic micropollutants such as polycyclic aromatic hydrocarbons (PAHs), polychlorinated biphenyls (PCBs), nonylphenol, xenobiotics, dioxins, pesticides, and heavy metals create important environmental health risks [3-7]. 

Endocrine disrupting compounds = Exogenous agents that interfere with the synthesis, secretion, transport, binding, action, or elimination of natural hormones in the body that are responsible for the maintenance of homeostasis, reproduction, development, and/or behavior (e.g., alkylphenols, alkylphenol polyethoxylates, polyaromatic hydrocarbons (PAHs), polychlorinated biphenyls (PCBs), phthalates, bisphenol-A, polybrominated flame retardants, dioxins, furans, herbicides, pesticides, and steroid hormones). 

For the sake of brevity, we will limit ourselves to listing a few of the endocrine disrupters of industrial origin and identified as polychlorinated biphenyls (PCB), polybrominated diphenyl ethers (PBDEs), phthalates, perfluorooctanoic acid, and... 

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