Toxaphene POPs

POPS currently regulated under the Convention include pesticides such as aldrin, chlorodane, DDT, dieldrin, endrin, heptachlor, mirex and toxaphene chemicals with industrial applications such as polychlorinated biphenyls (PCBs)2 and chemical byproducts such as dioxins and furans and hexachlorodbenzene, which fits in all three categories.3... 

A workshop participant reported that China has phased out the production and use of five of the POPs covered by the Stockholm Convention—aldrin, dieldrin, endrin, toxaphene and heptachlor. He explained that chlordane and mirex are still produced in limited quantities for termite protection and hexachlorobenzene (HCB) is still produced for use as a chemical feedstock. Mirex... 

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 POP protocol elaborated on occasion of the Stockholm Convention in 2001 contained 12 compounds, known as the dirty dozen aldrin, chlordane, DDT, dieldrin, endrin, heptachlor, HCB, mirex, PCBs, pol veil I orod i be nzo-/ -d i ox ins. polychlorodibenzofurans and toxaphene. After several years of implementation other compounds, were also included HCHs, PAHs, certain brominated flame retardants, perfluorooctanesulfonic acid (PFOS) and pentachlorobenzene (http // www.chem.unep.ch/pops/). This protocol is aimed to control, reduce and/or eliminate discharges, emissions and spills of POPs into the environment. 

Trace levels of toxaphene and mirex are detected in the air with no clear differences among the sampling sites, although both had never been registered as agrochemicals in Japan. HCHs, now being evaluated as candidates of the additional POPs by POPs review committee under Stockholm Convention, are also in comparable levels to PCB and chlor-danes in Japan as shown in Fig. 1.5. 

Organochlorine pesticides were predominantly used during the 1950s-1970s in China. DDT, HCH, toxaphene, HCB, chlordane, heptachlor, and mirex used to be produced in China. Historically, there have been 60 POP pesticide-producing enterprises, which were located in 18 provinces in China. 

China had produced many kinds of POP pesticides, i.e., DDT, HCB, HCH, chlordane, mirex, toxaphene, heptachlor, aldrin, and dieldrin, although some were produced only tentatively and on a very small pilot scale. While endrin has never been produced in China, DDT, HCH, HCB, toxaphene, and chlordane have been produced in relatively large amounts. 

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. 

In Hong Kong, the nine intentional POPs pesticides (aldrin, chlordane, DDT, dieldrin, endrin, heptachlor, HCB, mirex and toxaphene) targeted for global elimination or restricted production and use were not registered, or their registration status had been cancelled for many years due to toxicological or environmental concern. 

Contamination of local marine sediment by toxic chemical pollutants has been relatively well documented. The marine sediment POPs inventory was compiled based primarily on data generated from a major consultancy study on local toxic substances pollution (EPD, 2003a), EPD routine and ad hoc marine monitoring programmes of 2003/2004 and study reports published by local academia (Zheng et al., 2000 Muller et al., 2002 Tam and Yao, 2002 Wong et al., 2001, 2005). With the exception of mirex and toxaphene, all other POPs pesticides were detected in the... 

Levels of POPs in two local marine mammals, the Indo-Pacific humpback dolphin (Sousa chinensis) and Unless porpoise (Neophocaena phocaenoides), were measured in two ad hoc studies of stranded cetaceans in 1995-2000 and 2000-2001, respectively (Jefferson et al., 2002 Imanishi et al., 2004). Cetacean tissue samples were collected from stranded animals found in Hong Kong and analyzed for DDT, mirex, toxaphene and PCBs. High mean blubber concentrations of DDT (32.8 mg kg-1 ww) and PCBs (8.19 mg kg-1 ww) were reported. 

Results of the ecological risk assessment of POPs in the marine environment to local cetaceans (the hump-backed dolphins and the Unless porpoises) showed the HQs for eight POPs studied (chlordane, DDT, dieldrin, heptachlor, HCB, toxaphene, PCBs and dioxins/furans) were all less than unity, suggesting that there was no unacceptable risk of toxicological significance associated with exposure of local cetaceans to the current contamination level of these POPs in the marine environment (Table 7.17). 

In 1997, the United Nations Environment Programme (UNEP) Governing Council decided that immediate international action should be taken to protect human health and the environment. International negotiations to reduce and eliminate the emission and discharges of an initial set of 12 POPs were initiated at the Stockholm Convention on POPs in May 2001. The 12 substances that were addressed at the Stockholm Convention were aldrin, endrin, dieldrin, dichlorodiphenyltrichoroethanes (DDTs), polychlorinated biphenyls (PCBs), polychlorinated dibenzo-p-dioxins (PCDDs), polychlorinated dibenzofurans (PCDFs), chlordane, toxaphene, heptachlor, hex-achlorobenzene (HCB) and mirex. Basic information and status of major organochlorine pesticides in China are summarized in Table 8.1. 

The first official report on the import statistics of these chemicals was made in 1971. After this, the import of POPs chemicals increased year by year. There were increases and decreases year by year until various chemicals were banned in different years. For example DDT was banned for agricultural use in the year 1983 and totally in the year 1994 aldrin in the year 1988 dieldrin in 1986 endrin in 1981 heptachlor in 1988 toxaphene in 1982 HCB in 1980 and PCBs in the year 1975. Only chlordane remained in use until 1996 (www.chem.unep.ch/pops-Inc/). 

Import, export, manufacture, and possession of hazardous substances have been controlled under the Hazardous Substances Act, 1992. However, banning of the import or severely restricted uses of chemicals had been notified in the Ministerial Notifications since 1977. Two insecticides, namely chlordimeform and leptophos were the first two of the banned chemicals in 1977. According to the Act, Ministerial Notifications of the Ministry of Industry were issued to harming of nine specified POPs pesticides usage since 1980 (Table 10.4). Only seven specified POPs pesticides were imported and widely used in Thailand, namely aldrin, chlordane, DDT, dieldrin, endrin, heptachlor, and toxaphene, whereas hexachlorobenzene and mirex have never been imported. Although... 

Ritter, L., (1995). A review of the persistent organic pollutants DDT, aldrin, dieldrin, endrin, chlordane, heptachlor, hexachlorobenzene, mires, toxaphene, polychlorinated biphenyls, dioxins and furans. Geneva International Programme on Chemical Safety. www.chem.unep.ch/pops/indxhtms/assesO.html... 

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... 

Chirality has shown that at least some POPs are not likely to be biotransformed by some fish species. Some legacy POPs were racemic in fish, such as the toxaphene congener B7-1453 in cod liver oil [214], as well as cis- and ira 5 -chlordane, a-HCH, o,p -DDT, and photodieldrin in fish oils purchased from various countries [215]. Arctic cod Boreogadus saida) also had racemic amounts of a-HCH, cis- and ira 5-chlordane, U82, MC-5, and MC-7 [190, 216], as well as MC-6 [216] and PCBs [192]. Emerald rockcod (Trematomus bernacchii) in the Antarctic also had racemic residues of a-HCH [195]. 

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