Mirex sources

This statement was prepared to give you information about mirex and chlordecone and to emphasize the human health effects that may result from exposure to them. The Environmental Protection Agency (EPA) has identified 1,408 hazardous waste sites as the most serious in the nation. These sites make up the National Priorities List (NPL) and are the sites targeted for long-term federal clean-up activities. Mirex has been found in at least 7 of the sites on the NPL. Chlordecone has been found at 2 of the sites on the NPL. However, neither mirex or chlordecone are on EPA s list of target chemicals and the number of NPL sites evaluated for mirex and chlordecone is not known. As EPA evaluates more sites, the number of sites at which mirex and chlordecone are found may increase. This information is important because exposure to mirex and chlordecone may cause harmful health effects and because these sites are potential or actual sources of human exposure to mirex and chlordecone. 

Mirex has been detected in air, surface water, soil and sediment, aquatic organisms, and foodstuffs. Historically, mirex was released to the environment primarily during its production or formulation for use as a fire retardant and as a pesticide. There are no known natural sources of mirex and production of the compound was terminated in 1976. Currently, hazardous waste disposal sites and contaminated sediment sinks in Lake Ontario are the major sources for mirex releases to the environment (Brower and Ramkrishnadas 1982 Comba et al. 1993). 

Another source of chlordecone release to water may result from the application of mirex containing chlordecone as a contaminant and by the degradation of mirex which was used extensively in several southern states. Carlson et al. (1976) reported that dechlorinated products including chlordecone were formed when mirex bait, or mirex deposited on soil after leaching from the bait, was exposed to sunlight, other forms of weathering, and microbial degradation over a period of 12 years. Chlordecone residues in the soil could find their way to surface waters via runoff. 

Although mirex was identified at 7 of the 1,408 NPL waste sites (HazDat 1994), it is not known at how many of the sites environment samples were analyzed for this compound. Currently, hazardous wastes sites may still be potential sources for release of this compound to soil. 

Ninety percent of the mussels collected in 1985 at various points along the St. Lawrence River contained mirex at levels up to 1.6 pg/kg (ppb). The only source of mirex was contaminated particles entering the river from Lake Ontario mussels collected from the Ottawa River, which does not receive its water from Lake Ontario, did not contain any mirex. The mirex concentrations in the mussels decreased with distance from the lake (Metcalf and Charlton 1990). 

Mirex was not detected in 27,065 samples of food collected in 10 state food laboratories from 1988 and 1989 (Minyard and Roberts 1991). Mirex was also not detected in domestically produced or imported foods sampled as part of the FDA Pesticide Residue Monitoring Study during 1988-1989 (FDA 1990), was detected (at less than 1 % occurrence) in foods sampled in 1989-1990 (FDA 1991), and was not detected in foods sampled in 1990-1991 and 1992-1992 (FDA 1992, 1993). Mirex residues were detected in one sample of 806 composited milk samples collected through the Pasteurized Milk Program by the EPA in 1990-1991 (Trotter and Dickerson 1993). The milk was sampled at 63 stations that provide an estimated 80% of the milk delivered to U.S. population centers. At each station, milk from selected sources was composited to represent milk routinely consumed in the station s metropolitan area. The detection of mirex occurred in milk samples from Cristobal, Panama. 

Only two of the 28 milk samples (both from Oswego) were below the detection limit of 0.01 ng/g (ppb), while 16 of 24 colostrum samples in Albany, 10 of 18 colostrum samples from Oswego, and 2 of 4 colostrum samples from Rochester were below the detection limit. None of the women reported eating fresh water fish, a possible source of the mirex contamination (Bush et al. 1983a). 

Mirex is regulated by the Clean Water Effluent Guidelines as stated in Title 40, Sections 400-475, of the Code of Federal Regulations. Mirex has a specific effluent limitation for the pesticide chemicals point source category (EPA 1978f). No effluent guidelines exist for chlordecone. 

Source Hexachlorobenzene may enter the environment from incomplete combustion of chlorinated compounds including mirex, kepone, chlorobenzenes, pentachlorophenol, PVC, polychlorinated biphenyls, and chlorinated solvents (Ahling et al., 1978 Dellinger et al., 1991). In addition, hexachlorobenzene may enter the environment as a reaction by-product in the production of carbon tetrachloride, dichloroethylene, hexachlorobutadiene, trichloroethylene, tetrachloro-ethylene, pentachloronitrobenzene, and vinyl chloride monomer (quoted, Verschueren, 1983). 

The Binational Toxics Strategy between the USA and Canada has identified 12 bioaccumulative substances (referred to as Level-1 substances) having significant persistency and toxicity to the Great Lakes system, with the goal of reducing the sources of these substances to achieve naturally occurring levels [23]. Six of the 12 Level-1 substances are OC pesticides aldrin/dieldrin, chlordane, DDT, HCB, mirex, and toxaphene. Several other OC pesticides, such as endrin, heptachlor/heptachlor epoxide, hexachloro-cyclohexanes, tetra- and penta-chlorobenzenes, and pentachlorophenol, have been identified as Level-2 substances. 

Table 7.1 presents the local source characterization and quantification of the nine intentional POPs pesticides. There was neither import, export, manufacture nor use and no stockpiling of any of these pesticides in Hong Kong for the past five years (2000-2004). Transhipment of DDT was reported in 2000-2003 but not in 2004, while transhipment of mirex was recorded in 2004 only. 

Mirex was also found in the eggs of cormorants (Phalacrocorax sp.) from the Bay of Fundy on the Atlantic coast of Canada. The residue levels from 1975 (0.113 pg g-1 wet wt.) were double that of earlier levels from 1973 (0.058 pg g-1 wet wt.) and 1974 (0.059 pg g-1 wet wt.) (Kaiser, 1978). The source of contamination was suspected to be the southern wintering range in Florida and the Gulf of Mexico (Kaiser, 1978). 

Based on the activities that were initially conducted for the enabling activity project (Bravante and Medina, 2004), it was reported that little is known about POPs in the country and that even the users have minimal understanding of their hazards. As no comprehensive data on POPs is available for use as baseline information, a more comprehensive inventory is needed for the Philippines to have an actual measure of the risks that must be managed and addressed in the NIP. The Initial National Inventory conducted showed that POPs have already been banned in the country except HCB and mirex, which have no recorded use, importation or production in the country. Significant amounts of PCBs mainly come from electric transformers and capacitors. Dioxins and Source Inventory by DOST showed that there are numerous sources of dioxins and furans in the country, which emit significant quantities of dioxins and furans into the environment. No treatment facility in the country that deals with the destruction of POPs and other toxic hazardous wastes are present in the country (Bravante and Moreno, 2005). 

A number of complex chemical compounds (e.g., pesticides, vapors and fumes, automobile exhausts, petroleum distillates, foundry fumes, heterocyclic amines, solid particles) have caused adverse effects to humans and environment. Some persistent contaminants have originated from industrial sources. For example, DDT, mirex, PCBs, dioxin, and others have been traced in the atmosphere as toxic depositions causing concern to human health.3... 

Mirex is widely distributed in the sediment of Lake Ontario because of two sources (a) Hooker Chemicals (now called OxyChem) in the city of Niagara Falls, New York and (b) Armstrong Cork in the city of Oswego, New York. Mirex is now banned. 

Herring Gulls and the coho salmon living in L. Ontario have a common food source, alewives and smelt which are the next step lower on the food chain. Alewives and smelt are the common source of PCB, DDE mirex, photomirex, and chlorobenzenes to the gulls and salmon (Table ii) ( ). The same relationship for... 

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