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# >,"It:~~ Tom Cook, Chief Hazardous Waste Section Land Programs Department of Ecology Olympia, Wash. 98504

AQUANTITATIVE APPROACH TO CLASSIFICATION OF HAZARDOUS WASTE by
L. C. Mehlhaff*, T. Cook, 

### J. Knudson Hazardous Waste Section

Department of Ecology

Olympia, Washington

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* Sabbatical leave from Department of Chemistry, University of Puget Sound, Tacoma, Washington. '- \

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ABSTRACT 

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The approach to the classification scheme is fundamentally the same as used by EPA in their "Determination of Harmful Quantities of Hazardous Substances." The secondary aspect is to use criteria as designations and thus avoid the problem of providing lists of substances. Because this scheme is quantitative in its assessment ofhazard, it provides a method to relate toxicity to man, toxicity to wildlife, quantities of material and concentration of substances. Byutilizing the methods of "equivalent toxicity" and "categorization of substances" an overall continuity and uniformity is given to the designation scheme. These methods also have the advantage that simple assays ofwastes can be made by knowing the concentrations of ingredients in the waste. Using reasonable assumptions, itwill be shown that the poundage limitations of the EPA approach are rational from a leachate approach and a risk approach.

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### 4. The EPAproposed spill regulations,
s. Persistentmaterials. EquivalentToxicity Concept As you maybe aware, the proposed EPA spill regulation is a modification of the IMCO (Intergovernmental Maritime Consultative Organization of the UN) system. Materials are classified according to their aquatic toxicity (LCsO) into four categories, Category A - 

### LCs O.::. 1 ppm Category B

- LCSO= 

### 1-10 ppm Category C

- LCsO= 

### 10-100 ppm CategoryD - LCSO= 

### 100-500 ppm This EPA system recogniies that one pound of Category Asubstance is as toxic (will kill as many fish) as 10 pounds of Category B substance. Linearly extrapolating this system (with no antagonistic or synergistic effects), 10 pounds ofmaterial containing 10 percentYA" 

### substances (one pound) will be as toxic as 10 pounds of pure I'BII substances. Thus, each of the following have equivalent toxicities: 100 pounds of 1% "All substances (one pound of IIAII) 100 pounds of 10% "BII substances (10 pounds of IIBII) 100 pounds of 100% 

## "c" substances (100 pounds of IICtl ) 

### The choosing of the one pound ofmost toxic (Category A) as the lIharmfu1 quantityll was based on the fact that this is the smallest common commercial container size. While this assumption for wastes may not apply, other rationale to be discussed at the end of this talk do apply. We still think that the one, ten, and one hundred pound harmful quantities are entirely justifiable for the "f

### Loor" of our regulation. Human Toxicity Using a modified toxicity categorization developed for pesticides by FIFRA (EPAls Federal Insecticide, Fungicide, and Rodenticide Act), a categorization of substances based on acute oral LDsOls canbe made such that:Category A - LDs O.::. S mg/Kg Category B - LDs O= 

### S-SO mg/Kg Category C - LDSO 50-500 mg/Kg

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# \ We have developed in the State of Washington a classification system for hazardous wastes which is entirely consistent with existing definitions, but because of its quantitative basis allows a simple, realistic assay of a wastes' hazard. Background The Washington Legislature passed a hazardous waste bill in March 1976, requiring the Department of Ecology to adopt regulations for designation of Extremely Hazardous Waste. °The bills definition of Extremely Hazardous Wastel included the concept of a category called Dangerous Waste, of which Extremely Hazardous was a subset. The Extremely Hazardous was to be set-off from Dangerous because of "persistence, bioconcentration or genetic effects, and extreme toxicity, or because such quantities present an extreme hazard to man or wildlife." This Extremem1y Hazardous Waste was to be disposed of only at a site in Eastern Washington owned by the State and operated by a contractor, or to be detoxified. To avoid possible catastrophic criticism at the public hearing stage, the Department decided to develop the regulation through an Ad Hoc Committee. This committee of 28 represents as many facets of the waste community as we could justify in a "working connnittee." This committee has met approximately monthly since September to advise the staff. Constraints Besides the constraints·of the Lawand the Ad Hoc Committee format, it was our intention to: 1. follow as closely as possible existing schemes, 2. avoid a listing of extremely hazardous wastes or substances, 3. minimize the testing of wastes by utilizing known data where possible, 4. be realistic in our assay by avoiding the "any quantity and any concentration" trap, 5. be as simple as possible with our assay procedure. With these constraints and a little hand waving we came up with a system based on: 1. LD50's and LC50's (because of published data) 2. Acategorization approach to take account of the "softness" of data 3. The existing criteria for Extremely Hazardous of 1050 of 50 mg/Kg,

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### For a waste to be extremely toxic it should have an oral·LD50 of 50 mg/Kg (our basic criteria). Again, using the equivalent toxicity concept (assuming linear dilution effects), for a waste to be less toxic than our criteria itmust contain
a. less than 1% Category "A" substances, or b. less than 10% Category uB" substances, or
c. less than 100% Category 

### "c" substances. Usingjustifications shown later, the two categorization systems (oral and aquatic) canbe combined. Thus, Category A - OralLDs O 5 mg/Kg or Aquatic LCs O 1 ppm Category B - Oral LDsO

## =5-50 mg/Kg or Aquatic LCsO

## =1-10 ppm Category C - Oral LDs O

## =50-500 mg/Kg or Aquatic LCSO

## =10-100 ppm Quantity-Toxicity Interplay Utilizing the quantity concept developed by the EPA, and the concentration concept developed above, the regulation nowhas its boundaries. To seehow these concepts fit together, let's examine the example of a waste containing a Category "B" hazardous substance. Figure I is a plot utilizing pounds ofwaste as ordinate(y axis) and percentage of constituent "B" in the waste as abscissa(x axis). To cover the large range of concentrations and quantities wewill use a log scale on each axis. The vertical line (m,n) is representative of the oral LD50 = 

### 50 mg/Kgor 10% "B" in the waste. Wastes more concentrated in "B" wouldbe more toxic. The diagonal line (o,p) represents ten pounds of the constituent "B" in the waste. Below this line the waste contains less than 10 pounds of "B". It is helpful to examine the diagramby quadrants, with the aim of designating Extremely Hazardous Waste. The quadrant (m,p) should always be Extremely Hazardous Waste. These wastes would be extremely toxic as well as containmore than 10 pounds of "B". The quadrant (n,p) represents toxic wastes, but the quantity of "B" in these wastes is less than 10 pounds and ,thus not deemed a problem for regulation. The quadrant (o,n) similarly would notbe designated Extremely Hazardous Wastebecause it is not extremely toxic nor does it contain ten pounds of "B". The quadrant (o,m) offers more of a problem. Although thewaste contains more than 10 pounds of "B", the waste itself is not extrememly toxic. It can also be noticed that a designated Extremely Hazardous Waste in quadrant (m,p) could be placed in quadrant (o,m) by simply diluting that waste (i.e., with dirt). With these problems inmind weutilized a second part of our Act (sufficient quantity) to designate as Extremely Hazardous the hatched area in Figure I. This also gives a safety factor· of 10 in the designation. It should be pointed out that to move a factor of 10 lower would be to designate many sewage sludges as Extremely Hazardous Waste based on their metals content. I;r>
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.) Utilizing similar arguments, a diagram of the complete regulations can be constructed, Figure II. Note that for wastes which have data on the constituents present and for which LC

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### s Odata is available, an easy designation is possible. For wastes witfi no data, the generator could test the criteriaby most simply verifying that the LCSOof the waste was larger than 

### 100 ppm. We thus have two relatively s1mple methods of assaying the toxicity of the waste for designation as Extremely Hazardous. Persistence One of the major problems we had with our designation systemwas the legislative requirement of considering "persistence, and genetic effects." We finally decided to identify known materials by class and to specify tests to measure these materials as a separate section of the regulation. We thus designated "heavy metals, halogenated hydrocarbons, and aromatic hydrocarbons" as persistent and potentially having genetic effects. In order to avoid the trap ofregulating in the area of small quantities and low concentrations we chose to regulate only above 

### 100 pounds and 

### 1%. We similarly limited our broad swath to "soluble" substances, againwith specific test procedures to define soluble. Justification of AquatiC and Oral Poundage One of the greatest problems wehad with our systemwas to justify EPA's 

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### 100 pounds from both the aquatic standpoint (LC

### sO ) and the human exposure standpoint (LOS). We were thusly gratifiedwhen the

.following Leachate Approach ang Exposure-RiskApproach showed these

quantities to be the correct order ofmagnitude for regulating. ATechnical Rationale for Poundage Choice for EHW - ARisk Approach Using the concepts of equivalent toxicity it canbe shown that a landfill operator experiences the same risk (hazard) inhis daily operation with "normal" garbage as he would experiencewith one pound of Category "A" material at a landfill. The risk or hazard a landfill operator experiences is the product of three probability terms: 

### 1. The probability of ingestion, inhalation or dermal contact. 2. The probability of exposure to a hazardous material which couldbe ingested, and 3. The probability that this exposure would cause harm or have some**~ffect,** thus Risk

## =(probability of ingestion) (probability of exposure) (probability of effect)

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.It'will be assumed that the probability of ingestion, etc., is a constant

and not dependent on the character of the waste. In general, this will be true and the probability of ingestionwill be determined primarily by the operator and his personal work habits. The second and third termwill be waste dependent. The second term is quantity related, i.e., what poundage, or percentage of daily poundage of waste has the hazard or harmful characteristics as to cause an effect (term three). Assumptions A"normal" landfill operator services approximately 20,000 people, each generating approximately five pounds of "normal" garbage per day. Thus, the operator is exposed to about 100,000 pounds per day ofmaterial of the hazard of "normal" garbage (recognize that these arguments are order ofmagnitude in impact). What hazard is associated with "normal" garbage? Using the hazard ratings scale developed in the regulation, wastes are categorized by factors of ten according to their**~50.""** Although one could talk of LDS 's for garbage, the concept of LOS does not strictly hold for garRage, but certainly the concept of Razard does hold. Noting that categories Aand B are regulatedbecause of extreme hazard, Cbecause of quantity and hazard potential, Dbecomes whatmightbe"termed dangerous waste, and "normal" garbage becomes either category E or F inhazard rating, most reasonably Category F. Equivalent Toxicity Concept It can nowbe argued, using the equivalent toxicity concept, that 100,000 pounds of Category Fhazard is equivalent to 10,000 pounds of Category E, which is equivalent to 1,000 pounds of Category D, which is equivalent to 100 pounds of Category C, 10 pounds of Category B, and 1 pound of Category A. Thus, each of the following have the same risk: 1. 

### jLoo,OOO pounds of normal garbage (Category F). 2. 100,000 pounds of normal garbage containing 10,000 pounds of Category Ewaste. 3. 100,000 pounds of normal garbage containing 1,000 pounds of Category Dwaste. 4. 100,000 pounds of normal garbage containing 100 pounds of Category Cwaste. 

## s. 100,000 pounds of normal garbage containing 10 pounds of Category B waste. 6. 100,000 pounds ofnormal garbage containing 1 pound of Category A waste.

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......... It canbe seen that to not regulate one pound ofA, ten pounds of B, 100 pounds of C, would substantially increase the risk or hazard of the landfill, because of the ease of increasing these poundages, and hence, the overall risk. One of the most interesting facets of this hazard analysis is that it provides a framework for addressing immediate hazard at a landfill, and the basis for a total management scheme. Thus, Categories 

### Dand E material mightbe considered to be DW, and be regulated at poundage levels of 1,000 pounds for 

### D, and 10,000 pounds for E. Similarly, the hazard analysis indicates that Categories 

### Dand Ematerial, and possibly C, 

### B, and 

### Amaterial might be "properly managed" by the operator, thus, reducing risk number one (probability of ingestion, etc.) and keeping the general overall risk the same. Overall this analysis provides a realistic method of assessing materials, their handling, and the risks associated. 

### ATechnical Rationale for Poundage Choice for EHW-a Leachate Approach SUMMARY: Using reasonable assumptions, it canbe the LC50 value when diluted 100 to 1 by the regulated quantities 

### (1 pound 

### A, 10 allowed in a landfill. : ANALYSIS: shown that leachate will have ground water, if no more than pounds 

### B, or 100 pounds C) are

Using a previous assay of risk approach, no more than one pound of

### Awas allowed per 100,000 pounds of "normal" garbage. Maintaining this continuity, wewill assume the same values. Garbage will be assumed to have a density of. 200 pounds per cubic yard which will be compacted approximately three times when finally deposited in the landfill, thus: (100,000 pounds) 

## =500 yd

### 3 3**~OO** pounds/yd ) 3 3 (500 yd ) = 160 yd 3
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## \ If the landfill can be assumed to be 50 feet deep (16 yards), this garbage will have an exposed area of 10 square yards. Using one year's rainfall of 40 inches (100 centimeters), with 50 percent infiltration, 5,000 liters of water are available to leach this garbage. (10 yd2)(1 m 2/Yd2)(104 cm 2/m2)(100 em) (50%/100)

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## ..•. Assuming that Substance "A" is soluble to the following extent, all the one pound (500 grams) of "A" will dissolve in the 5,000 liters. This will create a leachate whose concentration is (500g) (5,000 1) 

### 0.1 gIl 100 gm/l

## =100 ppm [A computer similationmodel (SU1-1) developed by OSU (1) for these conditions show a leachate coming out of the landfill (at 400 hundred feet) four years after burial whose peak concentration is 20 ppm.) If one assumes a 30-acre landfill with a well, down gradient from the landfill one mile away, the dilution from rainwater of the leachate at the well would be 15 to 1 (a ratio) times 5 to 1 (distance ratio) equals 75 to 1. Similar calculations by**04-~~** (2) shows a minimum 100 to 1 dilution for wells one half mile from a 50-acre landfill. 'Heasured dilution at Llangollen, Delaware (3) shows**act~al** dilutions of landfill leachate to be greater than 100 at 2500 feet (one-half mile). Thus, if one pound ofA, ten pounds of B, or 100 pounds of Cper 100,000 pounds of garbage is deposited in the landfill, the leachate 1/2 to one mile from the landfill will approach the LC

# S8of the material regulated (A less than 1 ppm; B 1 to 10 ppm; C 10 to I 0 ppm). Thus, to not regulate one pound of A, 10 pounds of B, or 100 pounds of Cwould cause substantial damage to water resources into which the leachate flows.

BIBLIOGRAPHY 1. "Disposal of Environmentally Hazardous Wastes" - a report to the Oregon State Department of Environmental Quality

- December 1974. 2. Dawson, G. W., "Toxicological Criteria for Defining Hazardous Wastes"

- September 30, 1976. 3. Han, R. K., "The Generation, Movement, and Attenuation ofLeachates from SolidWaste Land Disposal Sites"

- June 1975.

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