;'

. ,

W()..7;J'\ .

>,"It:~~

Tom Cook, Chief

Hazardous Waste Section

Land Programs

Department of Ecology

Olympia, Wash. 98504

A QUANTITATIVE APPROACH TO CLASSIFICATION

OF HAZARDOUS WASTE

by

L. C. Mehlhaff*, T. Cook, J. Knudson

Hazardous Waste Section

Department of Ecology

Olympia, Washington

: .

* Sabbatical leave from Department of Chemistry, University of Puget

Sound, Tacoma, Washington.

'- \
1D)§©~DIW~f[J1

lI\~ MfJ.Y 18 1982 (1)j

------------ ----~
....- --.- .-'.---:~ ........ ~.""""'~~-~

... . .' . , . "~"-' ._.--- .

r-~' -;~:, \~.. ~)..•::

ABSTRACT

~~~? C

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 of hazard, it provides a

method to relate toxicity to man, toxicity to wildlife, quantities of

material and concentration of substances. By utilizing 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 of wastes can be made

by knowing the concentrations of ingredients in the waste. Using reasonable assumptions, it will be shown that the poundage limitations of the

EPA approach are rational from a leachate approach and a risk approach.

;t
4. The EPA proposed spill regulations,

s. Persistent materials.

Equivalent Toxicity Concept

As you may be 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

(LCs O) into four categories,

Category A - LCs O .::. 1 ppm

Category B - LCSO = 1-10 ppm

Category C - LCsO = 10-100 ppm

Category D - LCSO = 100-500 ppm

This EPA system recogniies that one pound of Category A substance 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 of material containing 10 percent YA" 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 of most 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 "fLoor" 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 can be 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

. - _..-. -"- ._.__•__. - _._-_:..__..:_- -.-..__.&_._...........---_._..- ...._-
\

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 Law and 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. A categorization approach to take account of the "softness" of

data

3. The existing criteria for Extremely Hazardous of 10 50 of 50

mg/Kg,
p.,

..

......".,.. C'

·t~;.

.,

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 it must contain

a. less than 1% Category "A" substances, or

b. less than 10% Category uB" substances, or

c. less than 100% Category "c" sub stances.

Using justifications shown later, the two categorization systems (oral

and aquatic) can be 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 now has its boundaries. To

see how 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 of waste 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 we will use a log scale on each axis.

The vertical line (m,n) is representative of the oral LD50 = 50 mg/Kg or

10% "B" in the waste. Wastes more concentrated in "B" would be 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 diagram by 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 contain more 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 not be designated Extremely

Hazardous Waste because it is not extremely toxic nor does it contain

ten pounds of "B".

The quadrant (o,m) offers more of a problem. Although the waste 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 in mind we utilized 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>

, .' .... -.

FIGURE

r-.

". f ;,.- -.

.' I

I __ (. • ...:, I

I

I

.........

.... '.: -', "';~ .

Always

.. EHW

/LD =50mg .

'" 50 Ikg m

Never , #J"P . • ". . . ......• », ...• . ,. . : 10 of ··8 '.":' .

EH W In Waste

10,000.

CD

-an 1,000

~~CD

-

8100

en

100,000

0»

~..2 10 --..... ...... c . ::J' .

o

0.

0.1

n

0.1 . I . 10 100

.% B in Waste

(log scale)'

Desigation for Category 8 Waste

~---~----- .

--- ~._- --- --~ --------
r:........ ~~~; »<

'""-.>-

.)

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

so

or LOs O data is available, an

easy designation is possible. For wastes witfi no data, the generator

could test the criteria by most simply verifying that the LCSO of 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 system was 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 of regulating 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, again with specific test procedures to define soluble.

Justification of AquatiC and Oral Poundage

One of the greatest problems we had with our system was to justify EPA's

1, 10, and 100 pounds from both the aquatic standpoint (LCsO) and the

human exposure standpoint (LOS). We were thusly gratified when the

. following Leachate Approach ang Exposure-Risk Approach showed these

quantities to be the correct order of magnitude for regulating.

A Technical Rationale for Poundage Choice for EHW - A Risk Approach

Using the concepts of equivalent toxicity it can be shown that a landfill operator experiences the same risk (hazard) in his daily operation

with "normal" garbage as he would experience with 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 could be

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)
ro .

I

c

--. :::s _ cOl c8 (R

(IJ

()

OOI~

:e

a

000&1

CD

MH3

fON

(aloos 601)

a~sDM U! aouD~sqns %

001 01 I ro

#1·

"

a

-#-01

O·

~OOI·.

MH3

000'01·

. 000'001

II . -'
r\

..... -<

...."!: .' .

I \\ I • '., ".

. 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 ingestion will be

determined primarily by the operator and his personal work habits.

The second and third term will 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 of material of

the hazard of "normal" garbage (recognize that these arguments are order

of magnitude 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 A and B are regulated because of extreme hazard, C because of

quantity and hazard potential, D becomes what might be" termed dangerous

waste, and "normal" garbage becomes either category E or F in hazard

rating, most reasonably Category F.

Equivalent Toxicity Concept

It can now be argued, using the equivalent toxicity concept, that 100,000

pounds of Category F hazard 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 E waste.

3. 100,000 pounds of normal garbage containing 1,000 pounds of Category D waste.

4. 100,000 pounds of normal garbage containing 100 pounds of Category

C waste.

s. 100,000 pounds of normal garbage containing 10 pounds of Category B

waste.

6. 100,000 pounds of normal garbage containing 1 pound of Category A

waste.
... . I 1 .

r:

~'....

,-"'.

.........

It can be seen that to not regulate one pound of A, 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 D and E

material might be 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 D and E material, and possibly

C, B, and A material 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.

A Technical Rationale for Poundage Choice for EHW-a Leachate Approach

SUMMARY:

Using reasonable assumptions, it can be

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 A was

allowed per 100,000 pounds of "normal" garbage. Maintaining this continuity, we will 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 . \

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 yd 2

) (1 m2/Yd2 ) (104

cm

2/m2)(100 em) (50%/100)

---------

5 x 106 3

cm 5 x 1031

j',

-- ----------'
·. "

, ..•.

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 similation model (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 of A, ten pounds of B, or 100 pounds of C per 100,000

pounds of garbage is deposited in the landfill, the leachate 1/2 to one

mile from the landfill will approach the LCS8of 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 C would cause

substantial damage to water resources into which the leachate flows.

BIBL IOGRAPHY

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 of Leachates

from Solid Waste Land Disposal Sites" - June 1975.

. -~ :;