Heptachlor 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... 

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. 

The government has been measuring PCB, HCB, DDT, chlordane, heptachlor epoxide and dieldrin since 1998 to identify their effects on wildlife as part of the Environmental Survey on Endocrine Disruptors. The specimens taken include land animals such as raccoons, bears, monkeys and frog, and marine mammals such as seals and whales, in addition to domestic birds and birds of prey. A relatively high concentration of POPs was seen in birds of prey and Phalacrocorax carbo. Eggs of mountain hawk eagles were also found to have a higher concentration of PCB, DDT, heptachlor epoxide, chlordane and dieldrin than other wildlife specimens... 

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. 

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... 

Table 14.2 summarizes available data on selected POP contamination in water in Malaysia. DDTs were found in most rivers in Malaysia but the concentration levels varied from region to region with centrally located rivers being detected to be highly contaminated. Surprisingly, DDTs concentration increased in these rivers as compared to rivers from other parts of the country even after DDT was banned from use in 1999. End-osulfans were not detected in most rivers in the 1989 survey but were found at relatively high concentrations in later studies (Table 14.2). Concentrations of other pesticides in river waters have also been reported in these studies. In the earlier study (Tan et al., 1991), aldrin, dieldrin, end-rin, and heptachlor were also found in some of the rivers. The concentration levels were ND-0.5 ng L-1 for aldrin, ND-0.3 ng L-1 for dieldrin, ND-3.2ng L-1 for endrin, and 0.3-3.4 ng L-1 for heptachlor. Our study...

Our studies on levels of OCPs in sediments collected from rivers in northern Peninsular Malaysia showed similar distributions (Hossain, 2001 Tan, 2001 Syahidah et al., 2003). Table 14.3 summarizes the concentration levels of some of the POP chemicals in sediments collected in Malaysia. Two studies have reported on coastal sediments from the west coast of Peninsular Malaysia. In the 1995 study, Wood et al. (1999) reported the presence of most OCPs in sediment samples collected in this area. The mean concentrations of the OCPs were similar to the findings of our study (Hossain, 2001) on similar samples 4 years later (Table 14.3). For example, the total heptachlor found was 3.74 pg kg-1 in the 1995 study and 1.84pg kg-1 in the 1999 survey. 

The oral reference dose (Oral RfD) is an estimate of the daily exposure of a person to a contaminant that is likely to be without appreciable risk of a deleterious non-carcinogenic effect during a lifetime (USEPA http //www.epa.gov/iris/). Oral RfD values for POP concentrations in seafood types are presented in Table 16.5, together with the daily intake of POPs from seafood consumed in Singapore. Daily intakes of POPs from seafood are below the oral RfD. The cancer benchmark concentration (Dougherty et al., 2000) represents the exposure concentration at which a lifetime cancer risk equates to one excess cancer death in one million persons. This level is defined as the public health protective concentration in the Congressional House Report to the Food Quality Protection Act of 1996 in the USA. Cancer benchmark concentrations were exceeded for DDTs, heptachlor, and PCBs (See Table 16.5). The cancer hazard ratio is the ratio of the MDI for a specific contaminant relative to the cancer benchmark concentration. The cancer hazard ratio represents the extent to which average daily exposure exceeds the benchmark concentration. The cancer hazard ratio of seafood consumption... 

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... 

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