Dirty Dozen chemicals

TABLE 13.4 EPA Maximum Contaminant Level (MCL) for Several Dirty Dozen Chemicals... 

This case study reviews the history of hexachlorobenzene from its heyday as an agricultural boon to its global ban a few decades later as one of the "dirty dozen" chemicals. 

A list of hazardous environmental chemicals, sometimes referred to as the dirty dozen, has been drawn up by the United Nations Environment Programme (UNEP). These are ... 

Chlorinated micropoUutants are harmful for man and environment due to their toxicity, persistence, and bioaccumulation. Persistent compounds are very stable and difficult to get metabolized and mineralized by biological and chemical processes in the environment, and as a result, they have become ubiquitous in water, sediments, and the atmosphere bioaccumulation is the result of the lipophilicity of these compounds. Polychlorinated dibenzodioxins and -furans (PCDD/F) are not produced purposely like many of other chlorinated technical products, such as chlorinated biocides DDT, lindane, and toxaphene. The production and use of persistent organic pollutants (POPs), the dirty dozen has now been banned worldwide by the Stockholm protocol. It should be mentioned that about 3000 halogenated products have now been isolated as natural products in plants, microorganisms, and animals," but the total amount of these products is much smaller compared to xenobiotics. 

The Stockholm Convention is a global treaty committing the international community to protecting human health and the environment from the potentially harmful effects of POPs (UNEP Chemicals, 2005). The United Nations Environment Programme (UNEP) has identified 12 most toxic POPs (the Dirty Dozen ) for control under the Convention, including 10 intentionally produced POPs pesticides/industrial chemicals (aldrin, chlordane, DDT, dieldrin, endrin, heptachlor, hexachlorobenzene (HCB), mirex, toxaphene and polychlorinated biphenyls (PCBs)) and two unintentionally produced POPs by-products (polychlorinated dibenzo-/ -dioxins (PCDDs) and polychlorinated dibenzofurans (PCDFs)). In implementing the Convention, Parties to the Convention will take measures to restrict the trade, production and use of the intentional POPs and to reduce and, where possible, to ultimately eliminate the production and release of the unintentional POPs by-products. 

The global POPs agreement initially covers the dirty dozen, which includes nine pesticides (aldrin, chlordane, DDT, dieldrin, endrin, heptachlor, hexa-chlorobenzene, mirex, and toxaphene), and three industrial chemicals (PCBs) and unintentional by-products (dioxins and furans) of industrial and combustion... 

In Chapter 13, we learned about the "dirty dozen"—12 chemical compounds that have been targeted by governments arotmd the world to be banned. These compounds are known as persistent organic pollutants (POPs) because once they enter the environment, they remain for long periods of time. Examine the structures of the compounds shown here. What functional groups can you identify within the compounds (They may have more than one.) What structural features do many of these compounds have in common ... 

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