DRAFT
EPA's Emission Standards for
Low-Arsenic Primary Copper Smelters
NAS Case Study
Ralph A. Luken
April 27, 1987
-------
CONTENTS
Chapter 1 Introduction
Chapter 2 Environmental Regulation fo the Copper
Smelting Industry
Chapter 3 Assessment of Risks from the Copper Smelting
Industry
Unit Risk Estimate
Public Exposure
Individual and Aggregate Risks
Chapter 4 Risk Management: Assessing Control Options
and Setting Final Industry Standards
Converter Fugitive Emission Controls
Matte and Slag Tapping Fugitive Emission Controls
Chapter 5 Exploration of Issues
Risk Assessment Issues
Risk Management Issues
r-
-------
- Chapter 1
INTRODUCTION
Section 112 of the Clean Air Act requires EPA to establish
emission standards for hazardous air pollutants that protect public
health with an "ample margin of safety." In interpreting the
language for the purposes of regulatory development, EPA does not
believe that the word "safety" implies a total absence of risk.
Many activities involve some risks, but are not considered "unsafe."
In EPA's veiw, standards under section 112 should protect the public
against significant health risks.
In setting a section 112 standard, EPA first defines what a
"significant risk" would be for the pollutant in question. It then
identifies sources of pollution that are likely to pose significant
risks, determines the current and planned levels of control at
those sources, and assesses the health risks associated with those
levels. Finally, EPA selects a level of control that, In Its
judgment, reduces the health risks to the greatest extent that can
reasonably be expected, after considering the uncertainties in the
risk analysis, the residual risks remaining after the application
of the pollution control technology, the costs of further control,
and the societal and other environmental impacts of the regulation.
This entire process is referred to as risk management.
Policy analysts and decision makers have long struggled with
how to best apply economic methods and assumptions when analyzing
-------
-2-
and control!ing "risk. On one hand, the limitations of economic
assumptions and 'ana-lysis have been widely discussed and have, in
fact, somewhat restrained their application to such areas as risk
management. On the other hand, the necessity of recognizing the
risk choices associated with, and the tradeoffs of,' regulatory
options argues for some role for economics in analysis and decision
making.
Debate over the use of economic principles and methods in risk
management eventually focuses on the underlying assumptions (usually
implicit) that relate to rational behavior, ethics, public choice,
and time preference. At this level, the issues concern notions
about equity, social values, philosophical presuppositions, and the
social contract between government and its citizenry.
This case study demonstrates how EPA used risk assessment and
risk management in setting standards for inorganic arsenic emissions
Chapter 2 provides some background on the regulatory history of the
copper smelting industry, while chapters 3 and 4 describe the risk
assessment and risk management information that served as a basis
for the regulation. The final chapter illustrates some of the
conceptual and methodological issues associated with the economic
analysis of risks. It shows how using different methods and
assumptions would have greatly changed the information available
for determining the final standard. More important, it asks whether
redesigning EPA's risk assessment and risk management techniques
would better reflect actual risks and protect the public against
those risks.
-------
Chapter 2
ENVIRONMENTAL-REGULATION OF THE COPPER SMELTING INDUSTRY
The primary copper smelting industry uses pyrometallurgical
processes to extract copper from sulfide copper ores containing
arsenic as an impurity. At the 15 primary copper smelters operating
in the U.S. in 1983, the average arsenic content of copper ore
ranged from 0.0004 to 4.0 percent. The average arsenic content of
the ore was well below 0.5 percent at the majority of smelters, and
only the ASARCO-Tacoma smelter processed ore with more than 1 per-
centarsenic.
On June 5, 1980, EPA published a Federal Register notice listing
inorganic arsenic as a hazardous air pollutant under section 112 of
the Clean Air Act (44 FR 37886). On July 11, 1983, EPA proposed
standards (48 FR 33112, July 20, 1983) for inorganic arsenic emis-
sions from the 14 low-arsenic primary copper smelters as well as
high-arsenic copper smelters and glass manufacturing plants. The
proposed standard for low-arsenic primary copper smelters regulated
secondary inorganic arsenic emissions from converter operations
and from matte and slag tapping furnances. The proposed standards
for converter operations applied to smelters with an annual average
inorganic arsenic feed rate of 6.5 kilograms per hour (kg/h) or
greater. And the proposed standards for matte and slag tapping
furnaces applied to smelters with an annual average combined inorganic
arsenic process rate of 40 kg/h or greater. The latter standards
were less restrictive than the former because secondary emissions
from converters are typically 1 to 25 times greater than the combined
emissions from both matte and slag tapping operations.
-------
-4-
The proposed standards affected 6 of the existing 14 low-arsenic
primary copper smelters. The estimated capital and annualized costs
required to meet the standards were approximately $35.3 million
and $9.5 million, respectively.
Because of public comments, EPA conducted additional analyses
to ensure that the final rule was based on the most complete and
accurate information available. These additional analyses included
revising the emission estimates, dispersion modeling, and risk
assessment, and conducting additional cost and economic impact
analyses. The scope of these analyses resulted in considerable
changes in the risk assessment and risk management information
that was incorporated in the final rulemaking of August 4, 1986
(51 FR 27956).
As a result, the final standard affects only one of the 14
smelters and does not apply to matte and slag tapping operations.
It applies only to smelters with annual arsenic feed rates to
converters greater than 75 kg/h . Because the only high-arsenic
copper smelter affected by the earlier proposal (one owned and
operated by ASARCO in Tacoma, Washington) ceased operation in 1985,
EPA withheld further action on the proposed standard for high-
arsenic primary copper smelters. EPA also confirmed its decision
not to regulate six other sources emitting inorganic arsenic.
The estimated capital and annualized costs required to meet the
final standard are approximately $1.8 million and $380,000,
respectively .
-------
Chapter 3
ASSESSMENT Of C-ANCER RISKS FROM THE COPPER SMELTING INDUSTRY
The quantitative estimates of public cancer risks presented in
this chapter are based on (1) EPA's linear non-threshold model,
which is a dose-response model that numerically relates the degree
of exposure to airborne inorganic arsenic to the risk of getting
lung cancer, and (2) EPA's Human Exposure Model, which expresses
numerically the degree of public exposure to ambient air concentra-
tions of inorganic arsenic from the 14 copper smelters. This
chapter describes these models and the assumptions used to assess
cancer risks and presents EPA's quantitative estimates of individual
and aggregate risks.
UNIT RISK ESTIMATE
The numerical constant that defines the relationship between
exposure to a pollutant (dose) and the potential health effects, or
risk (response), resulting from that exposure is called the unit
risk factor.
For an air pollutant, the unit risk factor is the excess cancer
risk associated with an individual's lifetime of exposure (70 years)
to an average concentration of 1 microgram per cubic meter (lx/{g/m3)
of the pollutant in the air. For inorganic arsenic, the unit risk
estimate is based on EPA's analysis of five data sets of the latest
smelter worker epidemological data collected by four researchers at
two smelters (Table 3.1). To establish a single point estimate,
EPA obtained the geometric mean for data sets within distinct
-------
-6-
Table 3.1
COMBINED UNIT RISK ESTIMATES FOR ABSOLUTE-
RISK LINEAR MODELS
Exposure Source
Study
Geometric
Mean Unit
Unit Risk Risk
i
Final Estimated
Unit Risk
Anaconda smelter
ASARCO smelter
Brown & Chu
Lee Feldstein
Higgins et al
Enterline &
Marsh
1.25 x 10-3
2.80 x 10-3
4.90 x 10-3
6.81 x 10-3
7.60 x 10-3
2.56 x 10-3
7.19 x 10-3
4.29 x 10-3
Source: U.S. EPA (1986)
and Arsenic Plants
"Inorganic Arsenic Emissions from Primary Copper Smelters
and Arsenic Plants - Background Information for Promulgated Standards,"
Appendix C - Inorganic Arsenic Risk Assessments for Primary Copper Smelters,
EPA-450/3-83-010^!.
b
-------
-7-
exposed populations, and took the final estimate to be the geometric
mean of those value's. Based on this analysis, EPA used a 0.00429
per ug/m^ unit risk estimate in assessing the health impact of
inorganic arsenic.
PUBLIC EXPOSURE
EPA applied the Human Exposure Model (HEM) to the 14 smelters.
This general model can produce quantitative expressions of public
exposure to ambient air concentrations. In addition, it carried out
more site-specific dispersion modeling at El Paso, Texas, and Douglas,
Arizona.
Table 3.2 lists, on a piant-by-plant basis, the total number of
people included in the exposure analysis. "Any risk" is the number
of people exposed to some degree to emissions from the specified
source, as calculated by HEM. "Maximum lifetime risk" is the
number of people exposed to the maximum individual risk, assuming
70 years of exposure.
INDIVIDUAL AND AGGREGATE RISKS
Unlike the unit risk factor, which concerns an individual's
lifetime exposure to an average concentration of a pollutant,
individual risk reflects an individual's probability of getting
cancer if continuously exposed to the estimated maximum concentration.
Aggregate risk is expressed as the total probable incidences of
cancer among all of the people included in the analysis, after 70
years of exposure. For statistical convenience, it is often divided
by 70 and expressed as probable cancer incidences per year.
-------
-8-
Table 3.2
NUMBER OF PEOPLE EXPOSED
Plant
ASARCO-E1 Paso
ASARCO-Hayden
Kennecott-Hayden
Kennecott-Hurl ey
Kennecott-McGill
Kennecott-Garf iel d
Phelps Dodge-Morenci
Phelps Dodge-
Dougl as
Phelps Dodge-Ajo
Phelps Dodge-Hidalgo
Copper Range-White
Pine
Magma-San Manuel
Inspiration-Miami
Tennessee Copper-
Copperhil 1
Any Risk*
493,000
46,800
46,800
26,300
7,350
810,000
25,500
31,100
6,600
2;560
16,900
211,000
35,700
164,000
Total
Number of
People Exposed
Maximum Life-
time Risk**
1
1
1
1
1
2
2
2
6
909
1
1
1
1
Distance
(km) from
Source
1.0
0.3
0.3
0.3
0.3
5.0
2.0
0.2
2.4
0.2
0.4
0.5
* A 50-kilometer radius was used for the analysis.
** People exposed within distance specified in next column.
Source: U.S. EPA (1986), "Inorganic Arsenic Emissions from Primary
Copper Smelters and Arsenic Plants - Background Information
for Promulgated Standards," Appendix C - Inorganic Arsenic
Risk Assessments for Primary Copper Smelters, EPA-450/3-83-
010^.
-------
-9-
Table 3.3 summarizes the maximum individual lifetime risk and
the annual incidence for baseline and promulgated control scenarios.
The baseline level of risks results from the level of emissions
after applying in-place controls or controls required to be in
place to comply with current state or federal regulations, but
before applying controls required by the final arsenic standard.
The converter control scenario level of risk represents the remaining
risks after implementing the final arsenic standard.
The final standard would reduce secondary inorganic arsenic
emissions from the one smelter by about 1 to 4 megagrams per year.
As a result of this emission reduction, EPA estimated that the lung
cancers due to inorganic arsenic for people currently living within
50 kilometers of the affected smelter would be reduced from 0.18-
0.38 to 0.16-0.29 incidences per year. The final standard would
reduce the estimated lifetime risk from exposure to airborne arsenic
from a range of 60-100 in 10,000 to a range of 50-80 in 10,000.
-------
-10-,
TABLE 3.3
RISK ESTIMATES FOR PRIMARY COPPER SMELTERS
Maximum lifetime risk
ASARCO - El Paso:!/
(1)
(2)
(3)
ASARCO - Hayden
Kennecott - Garfleld (Utah)
Kennecott - Hayden
4-i-I nsplratlon - Miami
Phelps Oodge - Oouglas(l)
mi/
Kennecott - Mcdll
*Phelps Do dqe - Hidalgo
*Phelps Oodge - Morencl
*Phel ps Dodge - Alo
*Kennecott - Hurley
*Tennessee Chemical - Copperhill...
*Copper Range - White Pine
Maximum L
Baseline x
10-4
10
5
10
13
0.6
3
1 .9
12
0.8
4
0.05
0.8
I .?
0.6
1 .6
1 .1
.ifetime Ri
Converter
Control x
8
5
9
12
0.6
0.5
1.0
2
0.7
0.6
0.03
0.2
1.7
0.5
0.1
0.4
0.15
sk
Reduction
x 10~4
2
1
1
1
o
2.5
0.9
10
0.1
3.4
0.02
0.6
0.3
0.7
0.5
1 .2
0.95
Annual ]
Basel ine
0.38
0.20
0.18
0.06
0.14
0.016
0.0069
0.022
0.025
0.006
0.0001
0.0028
0.0045
0.0008
0.003
0.0026
0.0004
ncidence, c
Converter
Control I/
0.29 4/
0.18 '/
0.16 ^/
0.05
0.14
0.0054
0.0034
0.0081
0.013
0.0015
0.0001
0.0009
0.0038
0.0003
0.0006
0.0017
0.0002
ases per year
Reduction
0.09
0.02
0.02
0.01
0
0.0106
0.0035 '
0.00139
0.012
0.0045
0
0.0019
0.0007
0.0005
0.0027
0.0000
0.0002
Controlof converter fugitive emissions
percent collection efficiency.
ny a system consisting of a secondary nood witn
' El Paso figures represent secondary arsenic emissions based: (1) on an emission factor for
uncontrolled converter fugitive emission of 15% of the arsenic contained in the primary converter
process gases, and (2) on a 3.75% emission factor. These figures are estimated by EPA to repre-
sent the upper and lower bounds of uncontrolled converter fugitive emissions at ASARCO-E1 Paso.
3 Risk estimates calculated using site-specific analyses ( ISCLT/Val 1 ey model) and 3.75% emission
factor.
4 Risk estimates calculated assuming no additional control by the building evacuation system
(BES) of emissions escaping the converter secondary hoods. Some control of these emissions by
the BES may occur although the amount of control can not be determined. To the exten.t that
emissions escaping the converter secondary hoods are controlled by the BES, these risk estimates
are overstated.
5 Risk estimates calculated using si te-s;peci f ic analyses ( ISCLT/Val 1 ey model).
*De minimi's risk.
NOTE
SOURCE
Tne baselIne level of risks results from the level of emission after applying in-place
controls or controls required to be in place to comply with current state or federal
regulations, but before applying controls required by the arsenic standard. The
converter control level of risk represents the remaining risk after implementing the
arsenic standard.
U.S. EPA (1986), "Inorganic Arsenic Emissions from Primary Copper Smelters and Arsenic
Plants - Background Information for Promulgated "Standards," Appendix C - Inorganic
Arsenic Rsk Assessments for Primary Copper Smelters, EPA-450/3-83-010f.
-------
Chapter 4
RISK MANAGEMENT:
ASSESSING CONTROL OPTIONS AND SETTING FINAL INDUSTRY STANDARDS
After determining the cancer risks from arsenic emissions, EPA
examined the two available options for control 1 ing ," or managing,
the risks: converter controls and matte and slag tapping controls.
This examination considered the estimated emission and risk reduction
from applying the options, the remaining public exposure to and
risk from inorganic arsenic after control, and the costs and economic
impacts of a standard based on those control options.
CONVERTER FUGITIVE EMISSION CONTROLS
The standard would require installing secondary hoods on
converters that have an annual average arsenic feed rate of 75
kilograms per hour or greater. The potential emission reductions
from, and the estimated annualized costs of, the converter secondary
controls at each of the existing smelters appear in Table 4.1. The
estimated cost-effectiveness ($/Mg) ranges from about $100,000 to
$8,000,000 per Mg at the 14 smelters.
Applying controls for converter secondary emissions would reduce
the range of estimated maximum risks to between 1.2 x 10~3 and 3.0
x 10~6 from a range of 1.3 x 10~3 to 5.0 x 10~6 (see Table 3.3).
It would also reduce the estimated annual incidence of lung cancer
from 0.38-0.0001 to 0.29-0.0001.
Using these risk and cost estimates, EPA concluded that for
eight copper smelters (identified with an asterisk (*) in Table
-------
-12-
Table 4.1
ENVIRONMENTAL AND COST IMPACTS ASSOCIATED WITH SECONDARY INORGANIC
ARSENIC EMISSION CONTROL SYSTEMS FOR CONVERTER OPERATIONS
Smel ter
ASARCO - El Paso:!/
(1)
(2)
ASARCO - Hayden
Kennecott - McGi 11
Kennecott - Hayden
Phelps Dodge - Douglas
Inspiration - Miami
Phel ps Dodge - Morenci
Kennecott - Utah (Garfield)
Phelps Dodge - Hidalgo
Tennessee Chemical - Copperhill . . .
Magma - San Manual
Phelps Dodge - Ajo
Kennecott - Hurley
Copper Range - White Pine
t m . r-
Arsenic
Content
of Feed
(percent)
0.5
0.5
0.42
0.033
0.015
0.03
0.033
0.006
0.144
0.003
0.0004
0.006
0.015
0.0005
0.008
Arsenic
Feed Rate to
Converters
(kilograms
per hour)
98.9
98.9
63.4
9.3
7.2
4.2
5.7
1.9
14.7
0.4
0.7
0.6
0.8
0.8
0.5
Potential
Secondary
Arsenic
Emissions
(megagrams
per year)
98.3
24.6
10.2
10.1
6.5
4.1
1.9
1.9
1.5
0.2
0.65
0.55
0.52
0.46
0.30
Baseline
Secondary
Arsenic
Emissions
(megagrams
per year)
13.3
3.4
5.4
10.1
6.5
4.1
1.9
1.9
1.5
0.2
0.65
0.55
0.52
0.46
0.30
Predicted
Secondary
Arsenic
Emission
Reduction?./
(megagrams
per year)
3.7
1.0
4.4
9.2
5.9
3.7
1.7
1.7
1.4
0.18
0.58
0.50
0.47
0.42
0.27
Annualized
Control
Costs
($1,000)
379
379
798
2,201
2 140
2,943
2,943
3,432
2,028
1 745
1,278
3 979
1,562
2,296
1,278
Cost per
Unit
Emission
Reduction
(dollar
per
(megagram)
102,430
379 000
181,365
239,240
362 710
795,405
1,731 000
2,019,000
1,449,000
9,694 000
2,203,000
7,958 000
3,323,000
5,467 000
4,733 000
fugitive emissions of 10% of the arsenic contained in the primary converter process gases and (2) on a 3.75%
emission factor. These figures are estimated by EPA to represent the upper and lower bounds of uncontrolled
converter fugitive emissions at ASARCO-E1 Paso.
2 Emission reduction estimates calculated, assuming no additional control by the building evacuation system (BES)
of emissions escaping the converter secondary hoods. Some control of these emissions by the BES may occur,
although the amount of control cannot be determined. To the extent that emissions escaping the converter
secondary hoods are controlled by the BES, these emission reductions are understated.
Source: U.S. EPA (1986), "Inorganic Arsenic Emissions from Primary Copper Smelters and Arsenic Plants -
Background Information for Promulgated Standards," Appendix C - Inorganic Arsenic Risk Assessments
for Primary Copper Smelters, EPA-450/3-83-010b.
-------
-13-
3.3), the baseline risk was insignificant, and that regulation
was not warrante'd. For five of the six remaining smelters that
the proposed standard would have affected, EPA concluded that the
costs were disproportionate to the risk reductions that could be
obtained. Furthermore, the economic analysis showed that for two
of these five smelters, the control costs were likely to result in
the smelters' remaining permanently closed (Kennecott - Hayden and
Kennecott - McGil1).
For the last remaining facility, ASARCO-E1 Paso, the analysis
indicated that risk could be reduced at a reasonable cost. An
additional factor considered in the assessment was that secondary
hoods will be installed on all converters at ASARCO-E1 Paso to
comply with requirements in the Texas SIP for attainment of the
national ambient air quality standard for lead. Since the costs
of the controls are reasonable and the control can be implemented
now, EPA decided that these controls should be applied only at
ASARCO-E1 Paso. Consequently, EPA revised the cutoff to cover
only facilities where the converter arsenic feed rate is 75 kg/h
or greater. Based on available information, this cutoff would
require applying converter secondary controls only at the ASARCO-E1
Paso smelter.
MATTE AND SLAG TAPPING FUGITIVE EMISSION CONTROLS
The standard would have required capturing and controlling
matte and slag process secondary emissions from smelting furnaces
-------
-14-
with arsenic process rates greater than 40 kg/h. However, all
three smelters above this cutoff have already installed localized
hoods over matte and slag tapping operations, and two have also
installed devices to control emissions of participate matter.
The potential emission reductions and the costs to control the
collected emissions at the smelters that are not currently controlling
them are summarized in Table 4.2.. The cost-effectiveness of these
controls ranges from $330,000 to $7,300,000 per Mg for the 14
primary copper smelters.
The risk reductions achievable through applying these controls
are insignificant because of the current low emission rates (less
than 1-2 Mg per year). In addition, controls on matte and slag
tapping operations are required by the Tripartite Agreement for
ASARCO-E1 Paso, so that no additional emission reduction would be
achieved by an inorganic arsenic standard. Controls on matte and
slag tapping operations at the remaining facilities would impose
costs that are greatly disproportionate to the risk reduction
achieved. Therefore, the proposed control requirement for matte
and slag tapping operations was not included in the final standard.
-------
-15-
Table 4.2
REVISED ENVIRONMENTAL AND COST IMPACTS ASSOCIATED WITH SECONDARY
INORGANIC ARSENIC EMISSION CONTROL SYSTEMS FOR MATTE AND SLAG TAPPING OPERATIONS
Smelter
ASARCO - Hayden
ASARCO - El Paso
Kennecott - Utah (Garfield)
Kennecott - Hayden
Inspiration - Miami
Phelps Dodge - Douglas
Kennecott - McGill
Phel ps Dodge - Morenci
Phelps Dodge - Hidalgo
Phelps Dodge - Ajo
Kennecott - Hurl ey
Tennessee Chemical - Copperhill ...
Magma - San Manuel
Copper Range - White Pine
Arsenic
Process
Rate
(kilograms
per hour)
98.2
102.1
40.4
9.4
19.8
10.4
5.6
5.0
0.8
1.8
1.6
1.1
1.0
0.6
Potential
Secondary
Arsenic
Emissions
(milligrams
per year)
8.5
6.7
2.0
0.9
0.8
0.6
0.3
0.3
0.05
0.1
0.1
0.09
0.08
0.06
Baseline
Secondary
Arsenic
Emissions
(megagrams
per year)
1.1
0.8
2.0
0.9
0.8
0.4
0.3
0.3
0.05
0.1
0.1
0.09
0.08
0.06
Predicted
Secondary
Arsenic
Emission
Reductions
(megagrams
per year)
0
0
1.7
0.78
0.69
0.32
0.26
0.26
0.04
0.09
0.09
0.08
0.07
0.05
Annual ized
Control
Costs
(1,000)
0
0
1,914
257
261
514
257
514
257
257
265
257
514
257
Cost per Unit
Emission
Reduction
(dollars
per megagram)
1,126,000
329 490
378 260
1,606 000
988,460
1,977,000
6,425,000
2,856,000
2,944 000
3,213,000
7,343 000
5,140 000
Source: U.S. EPA (1986), "Inorganic Arsenic Emissions from Primary Copper Smelters and Arsenic Plants
Background Information for Promulgated Standards," Appendix C - Inorganic Arsenic Arsenic Risk
Assessments for Primary Copper Smelters, EPA-450/3-83-010jf.
-------
Chapter 5
EXPLORATION OF ISSUES
The risk assessment and risk management information used in this
case study raises several issues about the methods EPA generally
uses to set standards. This chapter highlights some of these issues.
RISK ASSESSMENT ISSUES
Various methods and assumptions used in the case study's risk
assessment may have significantly overestimated or underestimated
the health risks from inorganic arsenic emissions.
Exposure for Entire Lifetime
Some of the basic assumptions implicit in the exposure methodology
are: (1) that all exposure occurs at people's residences, (2) that
people stay at the same location for 70 years, (3) that the ambient
air concentrations and the emissions that cause these concentrations
persist for 70 years, arid (4) that the concent rat 1 ons are the same
inside and outside the residences. In sum, they assume that indivi-
duals are exposed to inorganic arsenic emissions for their entire
1ifetime.
Several commentors questioned these simplifying assumptions,
particularly the assumption of 70-year resident immobility. If
EPA used a more reasonable assumption -- say, a 10-year residency
in the area -- then the maximum lifetime individual risk would
decrease by approximately one order of magnitude. However, this
10-year assumption would not change the annual cancer incidence,
because this calculation is independent of population mobility.
-------
-17-
Early Lifetime Exposure
Although the"estimates derived from the various epidemological
studies are quite consistent, there are a number of uncertainties
associated with them. The estimates were made from occupational
studies that involved exposures only after employment age was
reached. In estimating risks from environmental exposures through-
out life, EPA assumed in the linear non-threshold model that the
increase in the age-specific mortality rates of lung cancer was a
function only of emulative exposures, irrespective of how the
exposure was accumulated. Although this assumption adequately
describes all of the data, it may be in error when applied to
exposures that begin very early in life. Similarly, the linear
models possibly are inaccurate at low exposures, even though they
reasonably describe the experimental data.
Given greater access to the data from these studies, other
uGSe measures, as well as iiiuuel S Other than the linear nun-thresholu
model, could be studied. Such analyses would indicate whether
other approaches are more appropriate than the ones applied here.
Use of Census Data
The official EPA risk assessment (Table 3.3) underestimated the
maximum lifetime risk and annual cancer incidence at the El Paso
and Douglas Smelters because it did not include the Mexican popula-
tion living in border towns and illegally on plant property.
In the case of the El Paso smelter, the population in neighboring
Juarez is approximately the same as in El Paso. The maximum lifetime
-------
-18-
rlsk there is similar, 10~3, and the annual cancer incidence
ranges from .40 to .70, which is double the incidence among the
U.S. population. These estimates do not include the Mexicans
living illegally in the U.S. because they are not counted by the
U.S. Census.
In the case of the Douglas smelter, the population in neighboring
Agua Prieta is about double the population in Douglas. The maximum
individual risk is similar, 10~3, and the annual cancer incidence
is .04, which is double the incidence among the U.S. population.
If this information were incorporated in risk management decisions,
it would, as described later in this chapter, lower the cost per life
saved and increase the economic efficiency of the regulation, parti-
cularly at El Paso.
Assumption of No Latency Period
EPA's risk assessment assumes that there is no latency period
between exposure and incidence. Although there is no definitive
information on exactly what the latency period is for airborne
arsenic, it is greater that zero. Enterline and Marsh (1982)
suggest that it may be in the range of 10 to 19 years because
their standardized mortality ratios appear to become significant
about 10 - 19 years after the exposed workers have left the plant.
If this information were incorporated in risk managemnt
decisions, it would, as described later in this chapter, decrease
the economic efficiency of the regulation, particularly at El Paso.
Paso.
-------
-19-
Exclusion of Oth'er Health Effects
The unit risk e-stimate used in this case study applies only to
lung cancer. Other health effects are possible. These include
skin cancer, hyperkeratosis, peripheral neuropathy, growth retarda-
tion and brain dysfunction among children, and increase in adverse
birth outcomes. No numerical expressions of risks relevant to
these health effects are included in this study.
If more quantitative information about the health risks were
available and could be assigned monetary values, it would increase
the economic efficiency of the regulation at all plants.
RISK MANAGEMENT ISSUES
For each control option, EPA's risk management process considers
the magnitude of the risks, the degree to which risks can be reduced
by available control measures, uncertainties in the risk estimates,
the environmental and economic impacts, and the affordability of
the centre! measures. In this case, the decision resulted from
consideration of the economic impacts associated with the application
of controls, compared with the degree of risk reductions achievable
at the three smelters. However, the risk management paradigm, as
espoused by EPA, offers several other ways to think about the
necessity of imposing controls. These include consideration of
cost-effectiveness per incidence avoided, economic efficiency,
equity, and legislative consistency.
Cost-Effectiveness
To determine whether the standard is cost-effective in terms of
cases avoided, EPA must establish a reasonable value for a statistical
-------
-20-
life saved. The EPA Guidelines for Regulatory Impact Analyses
suggest that this v-alue should fall in the range of $400,000 to
$7,000,000, with a point estimate of $2,000,000. This value is
supported, in part, by a recent survey of 130 decisions made by
the U.S. government to regulate carcinogens (Travis', 1987). It
found that the average implicit value of a statistical life saved
was approximately $2,000,000.
If $2,000,000 is a reasonable value to consider in the decision
to control arsenic, then the figures in Table 5.1 suggest that the
standard is not cost-effective. They show that the cost per case
avoided exceeds $2 million at all plants. The cost per .case avoided
at the one plant regulated - El Paso lies between $4.2 million
A
and $18.9 million, depending upon assumptions about emission rates
and exposure.
If the $4,200,000 value at ASARCO - El Paso is thought to be a
reasonable value to initiate action, a case could still be made not
to control fugitive emissions from the converter at the plant. An
alternative risk assessment scenario at ASARCO - El Paso, described
in Table 3.3, shows a smaller reduction in cancer incidence (0.02)
and consequently a higher value per case avoided ($18.9 million).
These figures exceed the highest value in the Guide!ines and the
average value implied by past U.S. government regulatory decisions.
The scenario assumes that only 3.75 percent, rather than 15 percent,
of arsenic emissions escape the primary vent hood. The higher
emission factor of 15 percent reflects actual emissions before El
Paso upgraded its primary vent hood. The lower emission factor of
-------
-21-
ANNUAL COST PER
Table 5.1
CASE AVOIDED AND NET PRESENT
(millions of 1982 dollars)
VALUE (NPV) OF CONTROLS
Plant
ASARCO-E1 Paso (1)
(2)
( 3)_ly
Asarco-Hayden
Kennecott-Garfield
Kennecott-Hayden
Inspiration-Miami
Phelps Dodge-Douglas (1)
( 2)2/
Kennecott-McGill
Phelps Dodge-Hidalgo
Phelps Dodge-Morenci
Phelps Dodge-Ajo
Kennecott-Hurley
Tennessee Copper-
Copperhil 1
Magma-San Manuel
Copper Range-White
Pi ne
Annual
reduced
cases
0.09
0.02
0.02
0.01
0
0.0106
0.0035
0.0159
0.012
0.0045
0
0.0019
0.0007
0.0005
0.0027
0.0009
0.0002
Annual
cost/case
(10%, 0 yrs)
4.2
18.9
19.0
79.8
201.9
840.9
185.1
;?45.2
488.1
1306.3
2231.4
4592.0
473.3
4421.1
6390.0
NPV
( ben-cost)
(4%,0 yrs)
-1.6
-3.5
-3.5
-8.4
-22.3
-24.0
-36.5
-36.2
-36.3
-25.5
-21.6
-38.9
-19.1
-28.4
-15.9
-49.8
-16.0
NPV
( ben-cost)
( 10%, 0 yrs)
-1.7
-2.9
-2.9
-6.6
-17.3
-18.0
-25.0
-24.8
-24.9
-18.7
-14.9
-29.2
-13.3
-19.5
-10.8
-33.9
-10.9
NPV
( ben-cost)
(4%, 15 yrs)
-2.7
-3.7
-3.7
-8.5 '
-22.3
-24.2
-36.6
-36.4
-36.4
-25.6
-21.6
-38.9
-19.1
-28.4
-15.9
-49.8
-16.0
NPV
(ben-cost)
( 10%, 15 yrs)
' -2.9
-3.1
-3.1
-6.8
-17.3
-18.2
-25.0
-25.0
-25.0
-18.7
-14.9
-29.2
-13.3
-19.5
-10.9
-33.9
-10.9
1 Risk Estimates calculated using site-specific analyses (ISCLT/Val1ey model) and 3.75 percent
emission factor.
2 Risk estimates calculated using site-specific analyses (ISCLT/Val1ey model).-
Source: U.S. EPA (1986), "Inorganic Arsenic Emissions from Primary Copper Smelters and Arsenic
Plants - Background Information for Promulgated Standards," Appendix C - Inorganic Arsenic
Risk Assessments for Primary Copper Smelters, EPA-450/3-83-010b.
-------
-22-
3.75 percent reflects measured values at other sites (Hayden and
Takoma) where the equipment is similar to the upgraded vent hood
at El Paso, rather than actual measured values at El Paso after
installing the new equipment. The new emission factor is certainly
lower than 15 percent, which means that the cost pe'r incidence
avoided is higher than the lower bound of $4.2 million.
A counter to the above argument about the unreasonableness of
the cost per case avoided is that it fails to include the benefits
to the Mexican population. Including the Mexican population and a
high emission rate reduces the annual incidence by 0.265, rather
than the .09 reduction achieved with controls on fugitive emissions.
Consequently, the cost per case avoided is $1.4 million, rather
than $4.2 million. Including the Mexican population and a 1ow
emission rate reduces the annual incidence by 0.12, rather than
the .02 reduction achieved with controls on fugitive emissions.
Consequently, the cost per case avoided is $3.2 million, rather
than $18.9 million. These revised estimates suggest that the cost
per case avoided is consistent with EPA Guide!ines and other U.S.
government decisions. However, including the Mexican population
in the estimates for the Douglas smelter only brings the cost per
case avoided near to the high end of the range in the EPA GUI' del i nes
Economic Efficiency
EPA can determine whether a standard is economically efficient
by comparing the net present value of the standard's benefits and
costs (Table 5.1). With a 10 percent discount rate and no latency
period, no control option has a positive net present value, assuming
-------
-23-
$2.0 million per statistical life saved. Changing the discount to
4 percent does not "significantly change the results. The net
present value of all controls is negative. Thus, regulation at
all plants would be rejected on the grounds of economic efficiency.
Using a 15-year latency period changes only the economic
efficiency evaluation at the El Paso smelter. The magnitude of the
change in the negative net present value is greater for this plant
because of the greater proportionate reduction in the values for
cancer cases avoided. The assumption of a 15-year latency does
not markedly alter the negative economic efficiency evaluation at
the other 13 plants, because fewer cases are avoided, and the
control costs overwhelm the benefits in the net present value
calculations.
Assuming $7.0 million per statistical life saved only partly
alters the negative economic efficiency valuation at the El Paso
smelter. Using the highest reduction in annual incidence -- 0.09
cases -- makes the net present value positive for both discount
rates with no latency period, and for the 4 percent discount rate
with a 15Aear latency period. In all other circumstances at El
Paso (.09 incidence/10%/15 years and .02 incidence/any combination
of rates and years) and at all other smelters, the net present
value would remain negative, even for a relatively high value per
statistical life saved.
Although the EPA General Counsel ruled that EPA could not
look beyond the requirements of section 112 in setting this standard,
-------
-24-
this conference could examine whether the standard would be economi-
cally efficient if the total benefits of emission reductions were
compared against the costs. At El Paso, controls for fugitive
arsenic from converters would achieve a 6.6 megagram reduction in
lead (Pb) and a 30 megagram reduction in particulate matter {PM).
Controls at Douglas would reduce PM by 780 megagrams.
An immediate issue is how to.compare and aggregate these health
and welfare benefits. In the case of PM, there are reductions in
mortality, morbidity, and welfare damage (Table 5.2). EPA's
Guide!ines encourage monetizing these benefits and then adding them
together to obtain a dollar per ton number.
Incorporating the PM benefits into an economic analysis alters
the efficiency evaluation at the Douglas plant if one assumes
benefits at $3,800 per ton (Table 5.3). The PM benefit/ton number
typically ranges from $300/ton to $10,000/ton, depending on the PM
sources and exposure patterns for receptors near the sources. Using
these values makes the benefits equal to the costs, in contrast to
the negative net present value of $25 million - $36 million where
no PM benefits are considered, or a negative $16 million - $25
million for the scenario with $2,400/ton PM benefits.
Incorporating the PM benefits into an economic analysis of
controls at the El Paso plant does not alter the negative efficiency
calculation for any value within the range of $300/ton - $10,000/ton.
However, incorporating the Pb benefits yields a positive net present
value of $14 million - $26 million, rather than a negative net present
value of $1.6 million - $3.1 million.
-------
-25-
Table 5.2
LEAD AND PARTICULATE MATTER HEALTH AND WELFARE EFFECTS
Pollutant / Effect
Number Reduced . Benefits
Effects per Ton (Dollars) per Ton
Emission Reduction3 Emission Reduction
Lead
Chelation
Hypertension
Myocardial Infarction
Strokes
Mortal i ty
4
47
0
0
0
.5
.0
.1
.0
.1
4
3
3
case
case
case
case
s
s
s
s
deaths
$
$
$
$
$
1
1
6
0
8
1
260
.5
.5
.8
.4
.0
X
X
X
X
X
103
103
103
103
103
Total for Lead
$ 297.2 x 103
Particulate Matter
Mortality
Morbi dity
Lost Work-Days
Reduced Activity-
Days
Medical Expendi-
tures
Soiling and Material
Damages
4.3 x 10-5 deaths
8.8 person-days
27.9 person-days
Total for Particulate Matter
$
$
$
$
$
$
0.
0.
1.
0.
0.
2.
1
7
1
3
2
4
x
x
X
X
X
X
103
103
103
103
103
103
Effects based on county-weighted average for estimates of
reduced number of effects per ton of reduced pollution emissions
Range fo~r particulate matter total benefit value varies between
$0 and $300,000/ton for individual counties in the U.S. The
variation by county for the benefits of reducing lead emissions
was not calculated.
Source: Costs and Benefits of Reducing Lead in Gasoline: Final
Regulatory Impact Analysis.U.S. EPA,Office of Policy
Analysis, February 1985; Benefits and Net Benefits
Analysis for Alternative National Ambient Air Qualfty
Standards for Particulate Matter, U.S. EPA, Office of
Air Quality Planning and Standards, March 1983.
-------
-26-
Table 5.3
NET PRESENT DISCOUNT VALUES FOR BENEFIT-COST STREAMS OF PARTICULATE MATTER (PM),
LEAD, AND ARSENIC EMISSION REDUCTIONS
Pr
Reduced
Pollution
Plant / Pollutant Emissions
ASARCO-E1 Paso
Lead 6.6 tons
PM 29.5 tons
Arsenic!5
Scenario 1 3.7 tons
Scenario 2 1.0 tons
Total
Scenario 1
Scenario 2
Phelps Dodge-Douglas
PM 776 tons
Arsenicc
Scenario 1 3.7 tons
Scenario 2 3.7 tons
Totald
Scenario 1
Scenario 2
Scenario A
Scenario B
esent Value Benefits3
(Millions $)
Discount Rates:
4%
$36.7
1.0
2.4
0.5
$ 40.1
$ 38.2
$ 25.3
0.4
0.3
$ 25.7
$ 25.6
10%
$16.7
0.6
1.5
0.3
$ 18.8
$ 17.6
$ 15.9
0.3
0.2
$ 16.2
$ 16.1
Net Present Value
(Millions $)
Discount Rates:
4%
$ 26.0
$ 24.1
$ -10.8
$ -10.9
$ > 0.0
10%
$ 15.6
$ 14.4
$ -8.9
$ -9.0
$ >0.0
Assumes no latency period for assessing health and welfare effects for PM , lead and arsenic
ASARCO-E1 Paso Scenario 1 assumes that 15% of the arsenic emissions escape the primary
vent hood and Scenario 2 assumes that 3.75% of the arsenic emissions escape.
Phelps Dodge Scenario 1 risks 8ire based upon standard exposure analysis. Scenario 2 risks
are based upon site-specific analysis ( ISCLT/Val ley model).
The expected benefit per ton vailue for reductions in PM is $2,400/ton.
present value greater than zero with a discount rate of 4% (scenario A)
ton value must be at least $3,400/ton. The benefit per ton value given
rate (Scenario B) must be at loast $3,800/ton.
To achieve a net
the PM benefit per
a 10% discount
Source: Tables 5.1 and 5.2
-------
-27-
Equity
EPA may also"consider whether a standard meets an equity objec-
tive, rather than an economic efficiency objective. For example,
the conference might think that controls should apply in all circum-
stances where maximum lifetime risk equals or exceeds 1 in 1,000.
This risk level existed at three smelters - El Paso, Hayden, and
Douglas. However, the final EPA standard required application of
controls at only one facility (El Paso).
Legislative Consistency
An overriding risk management issue is whether the final decision
was consistent with the requirements of the Clear Air Act. As
required by section 122(b)(l)B of the Act, standards must be set
"at the levels which in [the Administrator's] judgment provides an
ample margin of safety to protect the public health" from inorganic
arsenic emissions.
EPA interprets section 112, as applied to non-threshold pollu-
tants, as a judgment about the degree of control that can be considered
amply protective. Two choices are available: either to set the
standards at zero to eliminate the attributable health risks, or to
permit some residual risk. In the absence of a specific directive on
this choice in section 112, and in recognition of the drastic
economic consequences that could follow from a requirement to
eliminate all risk from hazardous pollutant emissions, EPA believes
that it is not the intent of section 112 to eliminate all risks.
Standards that permit some level of residual risk can be considered
-------
-28-
to provide an ample margin of safety to protect public
health. Therefore," EPA set the emission standards for inorganic
arsenic at a level that may present some human health risk.
The National Resource Defense Council ( NRDC) is. chal 1 engi ng
EPA's interpretation of section 112. It thinks that basing standards
on the Best Available Technology places too much emphasis on non-
health issues, such as technologyi economics, and affordability.
Further, NRDC holds that protecting public health, rather than the
costs and the availability of technology, should be the primary
consideration in developing section 112 standards.
EPA's General Counsel ruled that EPA could not take the PM and
Pb benefits into account in choosing the final standard. If it
had the legal authority, it might have required emission controls
at the smelter at Douglas as well as at El Paso.
-------
References
Travis, C.C., S.A. Richter, E.A.C. Crouch, R. Wilson, and E. Klema
(1987). "Cancer Risk Management By Federal Agencies." Environ-
mental Science and Technology, forthcoming.
U.S. EPA (1986). "Inorganic Arsenic Emissions from Primary Copper
Smelters and Arsenic Plants - Background Information for Promul-
gated Standards." EPA-450/3-83-010b.
U.S. EPA (1986). National Emission Standards for Hazardous Air
Pollutants; Standards for Inorganic Arsenic." Federal Register
51 (149) : 27957-28042.
U.S. EPA (1985). "Costs and Benefits of Reducing Lead in Gasoline".
Final Regulatory Impact Analysis. EPA-230-05-85-006.
p
U.S. EPA (1984). "Health Assessment Document for Inorganic Arsenic,"
EPA-600/8-83-021f.
U.S. EPA (1983). "Benefits and Net Benefits Analysis for Alternative
National Ambient Air Quality Standards for Particulate Matter."
Final Regulatory Impact Analysis.
U.S. EPA (1983). "Guidelines for Performing Regulatory Impact
Analysis." EPA-Z30-1-84-003.
U.S. EPA (1983). "National Emission Standards for Hazardous Air
Pollutants; Proposed Standards for Inorganic Arsenic." Federal
Register 48 (140): 33112-33180.
U.S. EPA (1980). "National Emission Standards for Hazardous Air
Pollutants: Addition of Inorganic Arsenic to List of Hazardous
Pollutants." Federal Register 45 (110): 37886-37888.
------- |