EP toxicity

The testing of chemicals/wastes to establish the nature of their hazard capacity/threat in accordance with regulatory requirements falls into four categories (1) reactivity, (2) ignitability/flammability, (3) corrosivity, and (4) EP toxicity. Commercial chemical products, specific wastes, and wastes from specific processes may be listed as hazardous wastes because they are known to present toxic hazards in the manner of the tests above and/or are known to present serious toxic hazards to mammals/humans. In the discussion to follow, various chemical groups will be examined primarily in the context of reactivity, ignitability, and corrosivity. 

Corrective Action Application In Massachusetts, a municipal wastewater treatment plant receives a number of wastestreams containing heavy metals from local industries. When tested, the dewatered sludge failed the EP toxicity test. In order to permit landfill disposal of the sludge, solidification processes were examined. A soluble, silicate-based system, developed by Chemfix, was ultimately selected which produced a product whose leachate passed the EP toxicity test (Sullivan, 1984). 

The risk assessment has also concluded that a level of 200 mg/kg for lead in the soil will be a protective level for expected site exposures along with an excess cancer risk level for TCE-contaminated soil (56 pg/L). Based on investigations of activities at the site, the TCE-contaminated soil has not been determined to be a listed RCRA hazardous waste, as the cleaning solution records indicate the solution contained less than 10% TCE. However, the lead-contaminated soil is an RCRA hazardous waste by characteristic in this instance due to extraction procedure (EP) toxicity. None of the waste is believed to have been disposed at the site after November 19, 1980 (the effective date for most of the RCRA treatment, storage, and disposal requirements). 

A waste is toxic under 40 CFR Part 261 if the extract from a sample of the waste exceeds specified limits for any one of eight elements and five pesticides (arsenic, barium, cadmium, chromium, lead, mercury, selenium, silver, endrin, methoxychlor, toxaphene, 2,4-D and 2,4,5-TP Silvex using extraction procedure (EP) toxicity test methods. Note that this narrow definition of toxicity relates to whether a waste is defined as hazardous for regulatory purposes in the context of this chapter, toxicity has a broader meaning because most deep-well-injected wastes have properties that can be toxic to living organisms. 

The first step to be taken by a generator of waste is to determine whether that waste is hazardous. Waste may be hazardous by being listed in the regulations, or by meeting any of four characteristics ignitability, corrosivity, reactivity, and extraction procedure (EP) toxicity. 

Pesticides are very much a part of the definition of hazardous wastes (Table 11). In fact, the toxicity characteristic of hazardous waste as defined by RCRA (referred to as extraction procedure or EP toxicity) is based on threshold concentrations of eight metals and six pesticides in an extract of the waste (Table II-A). Sixteen of the specific hazardous waste streams listed by... 

C. Ink/paint wastes containing metals such as Chromium D007 EP Toxic... 

Many different chemical treatment systems have been developed to reduce the leachability of lead and cadmium compounds in flue dust. These systems usually rely on stabilization/solidification, adsorption, chemical reduction, or pH control. Chemical reduction employing the use of metallic iron has been successful in reducing the leachability of lead to below EP-Toxicity levels. Adding a 5 percent by weight dose of iron filings to cupola furnace emissions control sludge, for instance, reduced lead leaching from 28.6 mg/1 to less than 0.1 mg/1 (Stephens 1984). 

Foundries that generate furnace dusts that are EP-Toxic due to lead and cadmium have found that by carefully mixing the dusts with water treated calcium carbide desulfurization slag (which contains calcium hydroxide), they may be rendered non-EP-Toxic. Great care must be taken with this method since at high pH levels the lead may leach out. In addition to this problem, the effect of other hazardous materials in the dust and in the slag may still render this waste as hazardous (Stephens 1988). 

Turpin, P.D. et al. 1985. "Methods to Treat EP-Toxic Foundry Wastes and Wastewaters." American Foundrvmen s Society Transactions. 93 737-740. American Foundrymen s Society, Desplaines, Illinois. 

EP-toxicity Refers to toxicity derived using the Environmental Protection Agency s extraction procedures... 

The RCRA metal-containing aqueous wastes include characteristic wastes (D wastes) and the listed wastes (K and F wastes). The characteristic wastes are those containing any of the eight RCRA metals above the concentrations (EP Toxicity levels) identified in the Code of Federal Regulations (40 CFR Part 261.24). The F and K wastes are source-specific wastes and do not require any minimum metal concentration to be a RCRA hazardous waste. Table 1 identifies the RCRA waste codes chat have aqueous wastes with metals, and associated effective daces for land disposal restrictions. 

Melting Emission Control - Melt materials which contain significant amounts of certain heavy metals (such as lead, cadmium, and chromium) may result in wastes which are classified as hazardous due to EP Toxicity. 

Molding - Nonferrous alloy castings, such as brass and bronze, contain lead that may generate wastes which are classified as characteristic hazardous waste due to EP Toxicity. 

The emission control residuals sometimes exceeded EP Toxicity hazardous waste limits for lead and cadmium because the melting point of grey iron is approximately 2,700°F, where the melting point for lead is only about 620°F. As the metal is melted, the lead and cadmium will tend to volatilize and be collected by either the baghouse or wet dust collection emission control system. 

In a study (Boyle, et al., 1981) conducted by the American Foundrymen s Society (AFS) in conjunction with the University of Wisconsin and the USEPA, leaching tests were conducted on cupola emission control dusts and sludges from 21 different foundries. This study concluded that 9 out of the 21 foundries generated emission control residuals which would be considered as a hazardous waste on the basis of EP Toxicity for lead. Two other foundries generated emission control residuals which would be classified as hazardous on the basis of EP Toxicity for cadmium. Concentrations in the EP Toxicity Test for the 21 foundries ranged from less than 0.6 mg/1 to 130 mg/1. The mean lead... 

FOUNDRY CHARGE MODIFICATION EP TOXICITY TEST RESULTS... 

Various chemical means have been used to reduce the leaching potential of toxic metals. The four types of chemical treatment applicable to emission control residual waste which are EP Toxic for lead or cadmium include the following ... 

Evidence for a redox mechanism is found in EP Toxicity Test results. The addition of iron filings resulted in a final pH in the EP Toxicity Test slightly higher than untreated samples, indicating that the hydrogen ion may have been neutralized by chemical reduction. 

Listings as toxic waste Maximum concentration of contaminants for characteristic of EP toxicity (barium)... 

Maximum concentration of EP toxicity at hazardous waste sites Public drinking water Li mi ts ... 

Maximum concentration For EP toxicity at hazardous waste sites Maximum groundwater concentration Communi ty water systems Discharge to inland and tidal waters... 

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