Environmental Protection Agency Toxicity Research Articles

Toxic chemical wastes and the coincidence of carcinogenic mortality in Texas

Environmental‐justice proponents have argued that demographic factors unevenly affect the location of manufacturing and waste facilities and, thus, differences in exposure risks and outcomes. In this paper, statistical relationships among demographic factors, toxic chemical wastes released by Texas manufacturing facilities who participated in the Environmental Protection Agency's Toxics Release Inventory program in 1990, and carcinogenic causes of death were examined at the county level of analysis. Three types of carcinogenic death rates were regressed against the following county‐level variables: percent of the population under the age of 14, percent of the population 65 years of age and older, percent of population female in the childbearing ages of 15 to 44 years, percent Black population, percent Hispanic population, population density, percent of population employed in manufacturing industries, and per capita income. Results indicated that the elderly and young proportions of county population and the population density were the most important variables in explaining cancer mortality rates. Although some support was found for racially based correlations with the location of Toxics Release Inventory facilities and carcinogenic releases in the bivariate analysis, very little evidence was found among demographic and industrial factors that explained differences in cancer mortality rates. Implications of the findings for future research are discussed.

Characterizing environmental pressures along the US/Mexico border: An application of the Toxics Release Inventory in environmentrics

Public data bases are becoming increasingly available to environmental researchers. We discuss use of the U.S. Environmental Protection Agency's Toxics Release Inventory data base for research purposes in the context of characterizing a geographical area in terms of industrial toxic chemical emissions into the environment. We present as examples highlights of ongoing exploratory data summary for the U.S. side of the U.S./Mexico border area during 1988–1992 which show how different parts of the border area have unique patterns of emissions. The TRI was the first national industrial toxic emissions inventory, and constitutes a unique and useful resource for data on industrial toxic chemical releases in the United States for researchers prepared to invest in fully understanding its strengths and limitations.

The limitation of the toxicity characteristic leaching procedure for evaluating cement-based stabilised/solidified waste forms

The United States Environmental Protection Agency's Toxicity Characteristic Leaching Procedure (TCLP) is commonly used as a regulatory tool to determine whether or not a waste can be classified as a hazardous waste. The validity of the test procedure for assessing cement-based stabilized/solidified heavy metal wastes is examined in this paper. Synthetic cement-based heavy metal waste forms with different ANC were prepared and subjected to TCLP to study the effect of waste acid neutralizing capacity (ANC) on metal leaching. A “real” waste was also obtained from a local commercial treatment facility and tested to verify the findings. The results showed that as long as the stabilized/solidified waste forms have sufficient ANC to neutralize the acidity of the leachant, the leaching of metals will be small and the performance of the different waste forms cannot be differentiated. The test therefore has limited use in comparing the performance of different cement-based waste forms. A modified test procedure is proposed.

Thermal Immobilization of Lead Contaminants in Soils Treated in a Fixed- and Fluidized-Bed Incinerator at Moderate Temperatures.

Artificially lead-contaminated soils with different lead contents (200, 450, 600, and 900 ppm) were thermally immobilized in both fixed-bed and fluidized-bed modes at moderate treating temperatures (less than 500 °C) for various retention times. Cement powder and brick powder were added to the artificially contaminated soils to enhance lead immobilization. Results indicate that increasing treating temperature and time increases the extent of lead immobilization, as determined by the U.S. Environmental Protection Agency's (U.S. EPA) Toxicity Characteristics Leachability Procedure (TCLP). The percentage of lead leached from the soil/ cement mixtures was in the range of less than 0.251%, compared with the range between 13.6% and 40.7% for the corresponding soil/brick mixtures. As the amount of brick dust added to the Pb-doped soil was increased, the specific Pb immobilization effectiveness increased from 0.0675 to 0.149 mg Pb/g brick (for the 20- and 50-gram brick addition, respectively). An increase in air flow rate from 2 to 40 L/min caused a slight decrease in the Pb leaching percentage from 14.96% to 11.59%. Both the Freundlich and Langmuir isotherms give a satisfactory fit (r = 0.945 ~ 0.998) for the data derived from a TCLP test of the thermally-treated soil samples (105 °C and 500 °C) that contained lead contaminants. Sorption of lead contaminants in soil and sorbent matrices was the primary type of chemisorption. The kinetic results indicated that the Pb-doped soil system was too complicated to be described by a simple calculation.

EPA lists Toxic Chemicals to Help Protect Public from Accidental Releases

The Environmental Protection Agency (EPA) has published a new citizen's right-to-know list of toxic substances that is intended to enable communities to protect themselves from catastrophic accidental releases. This list of chemicals was mandated by the 1990 Clean Air Act Amendments. In addition to 25 substances specifically included by Congress, it contains substances EPA believes are the most likely to be accidentally released and cause injury. The list includes 77 acutely toxic chemicals, 63 flammable gases and liquids, and certain high explosives. EPA estimates that 115,000 chemical facilities, including manufacturing plants, public drinking water and waste treatment facilities, cold storage facilities, private utilities, and propane retail facilities will be affected by the regulation. Like the recent announcement on doubling the size of EPA's Toxics Release Inventory (C&EN, Jan. 17, page 4), this rule signifies this Administration's commitment to putting people first, EPA Administrator Carol M. Br...

Pentachlorophenol-treated wood poles and crossarms: Toxicity characteristic leaching procedure (TCLP) results

The purpose of this research was to develop a quantitative database on the leachable concentrations of pentachlorophenol and other organic compounds of interest from a population of pentachlorophenol-treated electric utility wood poles and crossarms through application of the Toxicity Characteristic Leaching Procedure (TCLP), as promulgated by the U.S. Environmental Protection Agency (EPA). The TCLP was applied to a total of 53 wood samples derived from 16 electric utility poles and 9 crossarms. Pentachlorophenol extract concentrations ranged from below the limit of detection 0.065 mg/L to 7.8 mg/L. The mean extract concentration for all samples was 2.09 mg/L. All samples had pentachlorophenol extract concentrations well below the EPA's Toxicity Characteristic (TC) regulatory level of 100 mg/L, classifying the treated wood as nonharzadous solid waste. Several other organic compounds subject to TC regulation, including 1,4-dichlorobenzene; 2,4-dinitrophenol; hexachlorobenzene; hexachlorobutadiene; cresols (m, o, and p isomers); nitrobenzene; pyridine; 2,4,5-trichlorophenol and 2,4,6-trichlorophenol also were measured in TCLP extracts. All of these organic compounds had extract concentrations well below their respective regulatory levels.

Organic Compounds in Ferrous Foundry Process Waste Leachates

An investigation is conducted to determine the potential for and extent of ground‐water contamination by organic matter arising from ferrous foundry solid‐waste landfills. In the laboratory, the Environmental Protection Agency's (EPA's) toxicity characteristic leaching procedure (TCLP) is used on waste samples representing nine common binder systems to identify organic compounds that may be released from these materials in landfills. Leachates are analyzed by gas chromatography/mass spectrometry (GC/MS) for qualitative analysis against a data base of 45,000 compounds, and by gas chromatography/flame ionization detector (GC/FID) for quantitative analysis. A field study at four ferrous foundry waste landfills is conducted to determine presence of organic compounds leached from the solid wastes. Laboratory results indicate that although a wide variety of organic compounds are detected, most are present at low concentrations. Core oil and phenolic urethane binder systems leached the largest number of organic ...

Modified sulfur cement encapsulation of mixed waste contaminated incinerator fly ash

As part of an effort to develop new and innovative materials for solidification/stabilization of mixed wastes generated at Department of Energy facilities, work is currently being performed at Brookhaven National Laboratory to encapsulate incinerator fly ash waste. A process using modified sulfur cement, a thermoplastic material with a melting point of 119°C, is described. Monolithic waste forms containing as much as 55 wt% incinerator fly ash have been formulated with modified sulfur cement, whereas maximum waste loading for this waste in hydraulic cement is 16 wt%. Compressive strength of these waste forms exceeded 27.6 MPa (4,000 psi). Wet chemical and solid phase waste characterization analyses performed on the fly ash revealed high concentrations of soluble metal salts including lead (Pb) and cadmium (Cd), identified by the Environmental Protection Agency (EPA) as toxic metals. Leach testing of the fly ash waste according to the EPA Toxicity Characteristic Leaching Procedure (TCLP) resulted in concentrations of Pb and Cd above allowable limits that define a characteristic hazardous waste. Encapsulation of fly ash (at waste loadings up to 43 wt%) in modified sulfur cement, with a small quantity of sodium sulfide added to enhance retention of soluble metal salts, reduced TCLP leachate concentrations of Pb and Cd well below EPA toxicity characteristic concentration criteria.

Heavy metal accumulation and transport through detention ponds receiving highway runoff

Sediment accumulations and associated heavy metal concentration into retention/detention ponds receiving highway runoff from several ponds and metal concentrations in various sediment layers were analyzed to determine the extent of vertical migration. Extraction of heavy metals had been evaluated using various solutions including the United States Environmental Protection Agency Toxicity Characteristics Leaching Procedures (TCLP). Also, sediments were incubated under various conditions of redox potential and pH to investigate the effects of changes in sediment conditions on the stability of metal-sediment associations.

Leaching characteristics of a high-calcium fly ash as a function of pH: a potential source of selenium toxicity

Using a modified extraction procedure, the effect of pH on the leaching of selected elements from Ca-rich (Type C) power plant fly ash was studied. Continuous additions of acetic acid were used to maintain pH values of fly ash slurries at 4.0, 6.0 and 8.0 for 24 h and an additional set was leached at its natural pH (average 11.8) value. Analyses for Se, As, Ca, Cd, Cr, Fe, Na and Pb showed that the highest concentrations occur in the leachate at pH 4.0 and decline with increasing pH. Concentrations of Cr and Fe increased slightly between neutral and high pH. Arsenic, Cd, Cr, Pb and Se concentrations exceeded the Environmental Protection Agency's toxicity criteria at pH 4.0. Selenium was above its toxicity level at pH values near 7 but the other elements were below their respective toxicity levels near neutral pH. Because recent studies show adverse effects of Se on aquatic life at far lower concentrations than the current Environmental Protection Agency's standard, high-Ca, power plant fly ashes represent a potentially hazardous pollutant to surface and subsurface waters.

Drilling Fluids and Reserve Pit Toxicity

Drilling fluids are now classified as exempt under the Resource Conservation and Recovery Act (RCRA) hazardous waste laws. Since 1986, however, the U.S. Environmental Protection Agency (EPA) has been studying reserve pit contents to determine whether oilfield wastes should continue under this exemption. Concerns regarding reserve pit contents and disposal practices have resulted in state and local governmental regulations that limit traditional methods of construction, closure, and disposal of reserve pit sludge and water. A great deal of attention and study has been focused on drilling fluids that eventually reside in reserve pits. In-house studies show that waste from water-based drilling fluids plays a limited role (if any) in possible hazards associated with reserve pits. Reserve pit water samples and pit sludge was analyzed and collated. Analyses show that water-soluble heavy metals (Cr, Pb, Zn and Mn) in reserve pits are generally undetectable or, if found in the total analysis, are usually bound to clays or organics too tightly to exceed the limitations as determined by the EPA toxicity leachate test. The authors' experience is that most contamination associated with reserve pits involves high salt content from produced waters and/or salt formations, lead contamination from pipe dope, or poorly designedmore » pits, which could allow washouts into surface waters or seepage into groundwater sources. The authors' analyses show that reserve its associated with water-based drilling fluid operations should not be classified as hazardous; however, careful attention attention should be paid to reserve pit construction and closure to help avoid any adverse environmental impact.« less

Production and disposal of wastes from dry and wet flue-gas cleaning systems

The design of a flue-gas cleaning system for the removal of particulates and sulfur dioxide contaminants must take into account many factors for there to be successful operation and no secondary environmental impacts. One of the factors which must be taken into account is the production of wastes and the procedures to be put into place for proper disposal. For many years, Argonne has had a high-sulfur dry scrubbing system in operation as the means of emissions control from its largest coal-fired boiler. During this period thousands of tons of a dry powdery waste have been produced and landfilled without any adverse environmental effects. This paper reviews the theory of operation of a dry scrubbing system, and briefly details the performance of the Argonne system over several years. Among the performance details given are the results of an experimental program utilizing a high-sulfur ( s>4.2%) coal, done in co-operation with the Consol Coal Company, and the findings from a study on the leachate, toxicity, and disposal of the dry wastes. The experimental programs, to date, have shown that a dry scrubbing system can technically and economically remove sulfur dioxide and particulates from flue gas produced from the combustion of high-sulfur coal. In addition, mixtures of dry scrubber wastes and fly ash have been subjected to the standard U.S. Environmental Protection Agency toxicity tests. The results of these tests indicate that while the ash composition of the coal will have a bearing upon test results, for the most part mixtures of this waste and coal fly ash can be declared non-hazardous.

Coal Conversion Solid Waste Disposal

The major solid waste produced at coal conversion facilities will be gasification slag or ash. To evaluate the impact of this waste on the environment, the Oak Ridge National Laboratory conducted extensive characterization and leaching studies on ash/slags that had been generated in bench-scale operations, pilot plants, and/or process development units for eight different gasification processes. These studies, designed to assess the consequences of disposal in landfills, showed that none of the leachates from these eight wastes exceeded the U.S. Environmental Protection Agency's toxicity limits. Thus, these ash/slags would be classified as nonhazardous wastes. Quantities of polynuclear aromatic hydrocarbons (PAH) that were observed in the aqueous leachates of selected ash/slags were less than 1 μg/g and appear to be of no significant environmental concern. Column elution studies revealed effluents with pH values less than three and sulfate concentrations greater than 10,000 mg/L for wastes containing sulfur concentrations from 0.3-4%. As a result, the major environmental impact associated with disposal of these solid wastes appears to be the dissolution of sulfate and the potential acidification of ground water.