Toxic substances include both naturally occurring and man-made substances that can cause adverse ecosystem or human health risks when exceeding certain concentrations. The Management Conference has reviewed all available data on the levels of toxic substances in the water, biota, and sediments of Long Island Sound. These levels were compared to applicable standards, criteria, and guidelines to provide an indication of environmental problems.
Overall, the quality of Long Island Sound’s waters is good with respect to toxic substances. The only documented case of levels exceeding either state’s water quality standards in the open waters of Long Island Sound is for mercury in the East River. However, data on organic toxic substances (such as polychlorinated biphenyls [PCBs]) were too sparse to allow the Management Conference to draw any conclusions about contamination. While few tests of water column toxicity have been conducted, indications of some aquatic life impairments have been observed in the upper East River.
Analysis of fish and shellfish tissue data indicates that very few contamination problems exist that could affect the health of seafood consumers. The only documented substances of concern are PCBs, most of which were discharged into the environment before the complete ban on their manufacture and severe restrictions on their use. PCB action levels (the minimum concentrations of chemicals in food that may cause the Food and Drug Administration to take enforcement action) are exceeded in the flesh of striped bass, bluefish, eels, and the hepatopancreas (more commonly known as the tomalley) of lobsters and crabs. The states of Connecticut and New York have issued consumption advisories for those species. Because PCBs are globally distributed and most fish and forage species migrate widely, it is not clear if the problem observed in Long Island Sound is caused by local sources.
There are also some concerns about contaminant levels in waterfowl tissues. New York state has issued an advisory on consumption of mergansers and some other waterfowl. The relationship between waterfowl contamination and Long Island Sound management needs is unclear because of the diversity of habitats and wide migration patterns of waterfowl. Connecticut has funded research into contamination of the greater scaup (a diving duck) that may provide additional insight into this type of problem and management needs for Long Island Sound.
Surveys of mussels and oysters, while spatially limited in scope, have identified a few areas where the concentrations of heavy metals and organic compounds in tissues are elevated relative to cleaner sites. These include the urban harbors of Bridgeport, Mamaroneck, and Hempstead, the lower Housatonic River near Devon, and the area around Throgs Neck. While the levels of contamination may affect the health of those species, there are no human health risk/consumption advisories as a result of toxic substances in these organisms.
Sublethal toxic effects on the pathology and reproductive success of organisms have been measured at some locations as well, specifically in flounder in New Haven Harbor and clams in Bridgeport and Norwalk Harbors.
In contrast to the generally low concentrations of toxic substances in the water, toxic contamination problems persist in the sediments of some areas of the Sound. This may be due, in large part, to historical discharges that occurred prior to implementation of state and federal Clean Water Act requirements. Despite the great strides in reducing the load of toxic substances to the Sound, field studies have not documented decreases in the amount of toxic substances in sediments in contaminated areas over time. The database since 1972, for example, does not identify general trends in sediment concentrations of heavy metals. This is probably a function of the slow sedimentation rate in the Sound combined with mixing of the sediments by burrowing organisms. More time is needed for the benefits of source reductions to be observed in the sediments because of these physical and biological attributes of the Sound.
While most of the Sound’s sediments do not exhibit contamination levels of concern, problems have been documented in some areas of the western Sound and in several, mostly urbanized, harbors, rivers, and embayments. In these areas, preliminary data indicate that elevated levels of metals in the sediment could be affecting benthic organisms. Sediments with elevated levels of metals and organic compounds are found in portions of Black Rock Harbor, Bridgeport Harbor, Stamford Harbor, the Quinnipiac River and New Haven Harbor, the Housatonic River, the Five Mile River, the West River, Glen Cove Creek, and the Hutchinson River. Sediments from sites in western Long Island Sound and in urban harbors have also elicited toxic responses in tests using sensitive species.
Overall, the Management Conference has concluded that problems due to toxic contaminants occur in limited areas and are primarily associated with sediment contaminant levels. However, additional data on toxic substances in water, biota, and sediments are essential to a full characterization of the nature and extent of the toxic substance problems in the Sound.
As discussed above, the sediment contamination problems that persist today may be due, in large part, to historical discharges of toxic contaminants. Active industrial and municipal sources of toxic substances still exist but have been greatly reduced. This is the result of the emphasis placed on toxic contaminant control in existing regulatory discharge permitting programs over the last 25 years. Currently, no single source category of toxic substances appears to be the primary determinant of conditions in the Sound. The results of the National Coastal Pollutant Discharge Inventory for the Sound, compiled by the National Oceanic and Atmospheric Administration for the Management Conference, indicate the following relative source contributions of some toxic substances to the Sound:
To protect and restore Long Island Sound from the adverse effects of toxic substances, the Management Conference recommends actions in four key areas:
Permit programs and enforcement activity for both direct and indirect discharges, including toxicity testing of those discharges, are responsible for greatly reducing toxic substance loads over the past 25 years. The Management Conference’s priority management recommendation for toxic substances is to continue these successful activities, all of which are funded under current programs.
Other programs that are designed to prevent pollution, reduce pollutant loads, or clean up existing problems and spills must also be supported as part of a comprehensive program to manage toxic contamination in Long Island Sound.
Planned activities under the auspices of the New York-New Jersey Harbor Estuary Program that will enhance toxic substance management in Long Island Sound are:
The states of Connecticut and New York will improve the coordination of health risk assessment and advisory recommendations. This will help minimize confusion about the safety of Long Island Sound fish, shellfish, and waterfowl, thus minimizing human exposure to contaminated species.
The Management Conference recommends that a comprehensive, coordinated monitoring program be implemented to fully evaluate toxic contamination problems and their causes and trends in the Sound. Elements of the program include:
In addition to these general monitoring recommendations, the New York-New Jersey Harbor Estuary Program has drafted a scope of work to develop comprehensive, systemwide models of PCBs, mercury, and other toxic pollutants. The Management Conference endorses these activities that will benefit Long Island Sound. Specific actions include:
The benefits of implementing the plan will be significant.