Great Lakes Binational Toxics Strategy

Draft Report and Findings on U.S. Challenges

Octachlorostyrene (OCS) Report: A Review of Potential Sources

EXECUTIVE SUMMARY

The Canada-United States Strategy for the Virtual Elimination of Persistent Toxic Substances in the Great Lakes Basin (Binational Toxics Strategy) challenges the United States to confirm by 1998 that there is no longer use or release from sources that enter the Great Lakes Basin of the industrial byproduct octachlorostyrene (OCS). Although OCS has recently been gaining attention because of its status as persistent, toxic, and bioaccumulative, very few government programs address this chemical. In particular, EPA has not previously compiled any inventory of sources and releases, regional or nationwide. This is likely due to the scarcity of data concerning the toxic effects of OCS in humans and the adverse effects on wildlife. Based on an extensive review of the literature, this report aims to characterize the potential sources, releases, and environmental loadings of OCS that may enter the Great Lakes Basin, identify whether sufficient information exists to confirm no use or release, and make recommendations for the Binational Toxics Strategy concerning OCS.

In the Great Lakes region, the St. Clair, Ashtabula, and Niagara rivers, in addition to tributaries to Lake Huron, are the sites of greatest OCS contamination. Sources at the head of the St. Clair River near Sarnia, Ontario, are suspected of contaminating Lake St. Clair and the Detroit River. Fish from Ashtabula, Ohio, where the Ashtabula River empties into Lake Erie, have been found to be highly contaminated with OCS. OCS-contaminated sediments from Lake Ontario have historically been correlated with the rise and fall of chlorine production along the Niagara River. Contamination of Lake Superior and Lake Michigan appears to be low, and what is there is thought to have resulted from long-range atmospheric transport.

OCS was first identified in Norway as a byproduct of magnesium production. It is now understood that OCS can be found in processes involving carbon and chlorine at high temperature, or with a high electrical flux, or processes involving aromatic compounds with chloroalkyl radicals. Initial sources of OCS identified in the U.S. involved the chlor-alkali industry, as carbon electrodes were used to electrolyze sodium chloride for production of chlorine and sodium hydroxide (NaOH, or caustic soda). Numerous chlor-alkali plants operated in the Great Lakes basin. Since most have converted to metal anodes, direct OCS process emissions, as measured by sediment levels at discrete locations, have dropped substantially. Landfill leachates from process residues still contribute OCS to the environment, but many of these will be handled under Superfund cleanup.

The release of OCS by the commercial production of chlorinated solvents as well as the incineration of PVC has been documented. Aluminum plasma etching and aluminum degassing methods have also been reported to generate OCS. A landfill used to dispose of chlorinated tars was found to be leaching OCS. Smelting operations to extract copper, nickel, niobium and tantalum, titanium, and vanadium have been implicated as sources of OCS. Additional processes identified as potential sources of OCS include secondary aluminum, copper, and lead smelting furnaces; fuel combustion and waste incineration processes; the production of ethylene dichloride/vinyl chloride; coke production; the manufacture of chlorinated phenols used in pesticides and wood preservation; bleaching processes and Kraft recovery furnaces in the wood pulp and paper industry. In general, it appears that whenever hexachlorobenzene (HCB) and chlorinated dibenzodioxins (CDDs) are formed, there is potential that OCS is also formed.

Incineration, combustion, and metal smelting operations, as well as chlorinated solvents production, may produce significant levels of OCS. Due to the scarcity of data characterizing OCS emissions and the lack of national emissions estimates, an approximation of OCS emissions by source category was derived from U.S. national emissions estimates for CDDs and HCB. This exercise was conducted as a tentative gauge of OCS emissions for selected potential sources and is presented for discussion purposes only. This exercise suggests a potential U.S. OCS emissions rate of 4,000 lbs/year. Insufficient information exists to determine approximate emission levels for several documented sources of OCS, such as magnesium production, aluminum plasma etching, aluminum degassing, and niobium and tantalum extraction operations.

Lacking complete data, confirmation of no use or release of OCS from sources that enter the Great Lakes Basin cannot be made. Actions to verify potential sources, including monitoring of OCS in the environment, are recommended. In keeping with the Binational Toxics Strategy’s emphasis on voluntary pollution prevention efforts, actions involving stakeholders to prevent, reduce, or eliminate the release of OCS in industrial processes may be undertaken simultaneously to reach the virtual elimination goal of the strategy.

In as much as OCS, chlorobenzenes, chlorostyrenes, chlorobiphenyls, chloronaphthalenes, and chlorinated dioxins and furans are formed concurrently in sources, these chlorinated compounds may have a cumulative effect more significant than that of OCS alone. OCS may serve as an effective marker compound for all of these compounds: it is a single isomer and is present at sufficiently high levels that analysis methods are not as costly or time-consuming as those for CDDs. In this way, an effective screening method may be developed. The reduction of OCS may indicate the simultaneous reduction of a range of co-generated compounds.