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National Dioxin Study Released

[EPA press release - September 24, 1987]

The U.S. Environmental Protection Agency today announced results of the National Dioxin Study, a two-year investigation of the extent of dioxin contamination in this country.

The study was conducted at Congressional request, following contamination incidents at Times Beach, Missouri, Love Canal, New York, and Jacksonville, Arkansas. The study consisted of investigation of dioxin in seven "tiers." The study was conducted under EPA's National Dioxin Strategy, which provides a coordinated approach for investigative, remedial and regulatory activities.

A major focus of the study was on 2,4,5 Trichlorophenol (2,4,5-TCP) production and manufacturing-use facilities and associated waste-disposal sites. The study also included investigation of 2,4,5-TCP related pesticide-formulation facilities, pesticide-use areas, certain other organic-chemical production facilities and a number of combustion facilities. Several hundred soil and fish samples were collected from sites around the country.

The study found that most contamination was limited to facilities involved in the production or manufacturing use of 2,4,5-TCP and at sites which received production wastes from such facilities. A number of these sites have large volumes of highly contaminated material. Some of these sites already appear on the National Priorities List--the agency's list of hazardous-waste sites potentially posing the greatest long-term threat to human health and the environment--for problems other than dioxin contamination. At highly contaminated sites, immediate action was undertaken to control human exposure.

Fish contamination at levels of concern has previously been confirmed near certain chemical plants. The National Dioxin Study sampling has resulted in dioxin (specifically, 2,3,7,8-TCDD) fish advisories for a number of additional rivers and a follow-up study of discharges from pulp and paper mills.

EPA conducted both random and targeted fish sampling. Although a majority of the fish samples were "non-detect" for dioxin, fish contamination appears to be a cause for concern in a number of areas. In the Great Lakes, targeted sampling n areas subject to industrial activity found contamination in 23 of 29 samples. A number of fish-consumption advisories have been issued as a result of the study, supplementing advisories already in effect. The agency has worked with state and local health officials to interpret the results.

EPA identified 100 production facilities and associated dioxin-contaminated sites, considerably fewer than the original projections of 400 to 500. The majority of these areas are in Missouri, where waste oil mixed with dioxin-contaminated production wastes was used to control dust on roads, parking lots and horse arenas.

EPA also investigated a sample of pesticide-formulation facilities. As a result, the agency estimates that approximately 10 percent of the 300 to 600 formulators may have some contamination. Few of the facilities with positive dioxin levels had extensive or severe contamination. The two formulators with higher levels were large facilities. EPA is conducting follow-up at the remaining large formulation facilities.

Limited sampling was conducted at pesticide-use areas such as forests, rice fields, rangelands and right-of-ways. While the levels in these areas were somewhat higher than background levels, they were generally less than 10 parts per trillion and are not a cause for concern, EPA said.

For a large majority of urban and rural soil samples, dioxin was not detected at the parts-per-trillion level. One part per billion is generally considered to be an acceptable level in residential soils, although lower levels may be of concern where animal grazing occurs.

The agency conducted a limited amount of combustion-source sampling in response to assertions that all such sources emit 2,3,7,8-TCDD. EPA obtained stack-emissions data at 12 facilities such as kraft recovery boilers, sewage-sludge incinerators and a secondary copper smelter. Dioxin emissions and those of dioxin-related materials were detected from all of the facilities tested. While 2,3,7,8-TCDD was detected at seven of the 12 sources, there was considerable variability in dioxin emission levels for these facilities. The facility with the highest dioxin emissions, a secondary copper smelter, has permanently closed.

In July 1987, as a result of a separate study, EPA announced plans to set standards for air emissions from municipal waste combustors. The agency issued guidance to the states to ensure that best available control technologies are used on new facilities even before the development of the upcoming regulations. The agency also plans to propose guidelines to the states for use in developing performance standards for existing facilities.

As a result of information obtained during the National Dioxin Study, EPA began an investigation of dioxin contamination from pulp and paper mills. The study, conducted jointly with the American Paper Institute, collected and analyzed wastewater and sludge samples from five mills across the country. Dioxin was detected in effluent wastewaters at three of the mills, in waste-treatment sludges at all five mills and in bleached pulps at four of the mills. EPA, in conjunction with other agencies, will continue to investigate this matter, including the question of whether any products produced by these plants are contaminated and pose any risk to public health.

Three states (Maine, Wisconsin and Minnesota) have issued fishing advisories as a result of this problem, and Maine, Wisconsin and Ohio have considered regulating land spreading of sludge. EPA assisted the states in establishing fish-consumption advisories and sludge-disposal regulations. EPA will begin regulating the discharge of dioxins from paper mills shortly to reduce levels in the effluents. Research is also underway on ways to reduce the discharge and to reduce or eliminate the production of dioxin, which is apparently a result of bleaching pulp with chlorine.

EPA has promulgated or proposed a number of regulations to control and prevent the introduction of dioxin into the environment. Stringent treatment and disposal requirements have been imposed on industrial wastes potentially highly contaminated with dioxin. The agency continues to conduct and support research into health effects of dioxin on humans, fish and other animals.