OAR Box 1833 

Prepped by Keeia Richards 

Document Number: 

97) l-A-4 

Docket Number: 

A-88-02 

Printed 11/14/2008 11:01:30 AM Sheet 97 of 172 

P.1 
P.2 

A-88-02 

The information on health or risk assessment in this report 

was compiled before the Clean Air Act Amendments (1990) but 

was not used in the development of the Chromium NESHAP. 

H @ B (1 W li 

Jl J * I 8(991 

EPA AIR DOCKET | 
P.3 

A-88-02 

X-R-M 

CHROMIUM EMISSIONS FROM CHROMIUM ELECTROPLATING OPERATIONSTECHNICAL REPORT 

Emission Standard Division 

U.S. Environmental Protection Agency 

Office of Air and Radiation 

Office of Air Quality Planning and Standards 

Research Triangle Park, North Carolina 27711 

November 1985 
P.4 

TITLE OF CONTENTS 

Page 

LIST OF TABLES.. ii 

A. Definition of Source Category 1 

1. Plants in operation and processes 1 

2. Projections of industry growth 2 

B. Emissions and Control 4 

C. Potential for Improved Control 7 

D. Risk Assessment Inputs 9 

1. Annual incidence 9 

2. Maximum individual risk 11 

E. References 14 

LIST OF TABLES 

Table 1. Ranges of Operating Parameters for Hard and Decorative 

Chromium Plating Operations 

Table 2. Uncontrolled Emission Factors Used to Estimate 

Emissions from Chromium Electroplating Operations 

Table 3. Emission Reductions and Annualized Cost of Control for 

Four Model Chromium Electroplating Operations 

Table 4. Risk Assessment Inputs for Calculating Annual 

Incidence Due to Hexavalent Chromium Emissions from 

the Chromium Electroplating Source Category 

Table 5. Risk Assessment Inputs for Calculating Maximum 

Lifetime Risk Due to Hexavalent Chromium Emissions 

from the Chromium Electroplating Source Category 

Table 6. Risks Associated with Exposure to Uncontrolled 

Hexavalent Chromium Emissions From Model Chromium 

Electroplating Operations 

Page 

3 

5 

8 

10 

12 

13 

n 
P.5 

TECHNICAL REPORT: 

CHROMIUM ELECTROPLATING 

A. Definition of Source Category 

The chromium electroplating source category comprises two distinct 

types of plating operations: "hard" and "decorative." In hard plating, a 

relatively thick layer of chromium is deposited directly to the base 

material (usually steel) to provide wear resistance, low coefficient of 

friction, hardness, and corrosion resistance or to build up surfaces that 

have been eroded by use. Hard plating is used for items such as hydraulic 

cylinders and rods, industrial rolls, zinc die castings, plastic molds, 

engine components, and marine hardware. In decorative plating, the base 

material (e.g., brass, steel, aluminum, or plastic) is generally plated 

with a layer of nickel followed by a relatively thin layer of chromium to 

provide a bright, tarnish-resistant surface. Decorative plating is used 

for items such as automotive trim, metal furniture, bicycles, hand tools, 

and plumbing fixtures. Although other types of operations performed at 

electroplating plants involve chromium in some form, this source category 

includes only those processes that use chromic acid in an electrolytic 

cell to deposit chromium metal on a product. 

1. Plants in operation and processes. There are about 9,700 chromium 

electroplating operations in the country. Chromium electroplating is 

used in the manufacture of a wide variety of industrial and consumer 

items. In general, chromium plating operations are located at or near the 

industries they service, which are usually in centers of high population 

density. Plating operations range in size from small shops operating one 

400-gallon tank for as few as 15 hours per week to large shops operating 

five 17,000-gallon tanks for as many as 130 hours per week. Most plating 

operations are "captive" processes performed within larger manufacturing 

facilities. Some operations are "job shops" that provide custom plating 

services for many different clients. Captive platers and job shops may 

perform either hard or decorative plating or both. 

The actual chromium plating process is similar for hard and decorative 

plating although pretreatment processes and operating parameters may 
P.6 

differ somewhat. The plating process involves placing the item to be 

plated in a tank containing chromic acid solution and a small amount of 

sulfuric acid as a catalyst. Direct electrical current is passed from an 

anode (positive electrode) through the plating solution. This results in 

chromium depositing out of solution onto the workpiece, which is the 

cathode (negative electrode). (In the case of plating a plastic, the 

pretreatment process includes steps to render the surface conductive prior 

to plating.) Typical operating parameters for both hard and decorative 

plating are shown in Table 1. 

The chromium plating process is very inefficient. Only 10 to 

20 percent of the power applied is used to deposit chromium onto the 

workpiece. The balance is consumed by the generation of hydrogen gas at 

the surface of the cathodes. Plating efficiency can be improved in some 

situations by adding fluoride to the plating solution. However, fluoride 

cannot be used in all types of plating solutions and may cause "etching" 

or "burning" of exposed steel surfaces if used in hard plating 

solutions. 

2. Projections of industry growth. Chromium electroplating is not a 

distinct industry; it is a process performed within and for a wide variety 

of industries. Thus, the growth of chromium electroplating operations is 

determined by trends in the industry sectors that require these services. 

Although new electroplating operations may be built to accommodate growth 

in specific industries or to replace obsolete or relocated equipment, no 

net increase in the use of chromium electroplating is expected. The 

following considerations form the bases for this conclusion: (1) chromic 

acid consumption by metal platers has remained relatively constant over 

the past 10 years, and (2) the demand for decorative plating in the 

automobile industry (one of the largest consumers of chromic acid for 

metal plating) has decreased because of the use of substitute materials 

for bumpers and trim. 
TABLE 1. RANGES OF OPERATING PARAMETERS FOR,HARD AND 

DECORATIVE CHROMIUM PLATING OPERATIONS ' 

P.7 

Hard plating 

Decorative 

plating 

Plating thickness, ym (mil) 

Plating time, min 

Chromic acid concentration, g/a 

(oz/gal) 

1.3 to 762 

(0.05 to 30) 

20 to 6,000 

225 to 375 

(30 to 50) 

0.03 to 2.5 

(0.001 to 0.1) 

0.5 to 5 

225 to 375 

(30 to 50) 

Temperature of solution, °C (°F) 

Voltage, volts 

Current, amperes 

49 to 66 

(120 to 150) 

38 to 46 

(100 to 115) 

(Depends on the distance between 

the anodes and the items being 

plated.) 

(Depends on the amount of surface 

area being plated.) 

Current density, amperes/m' 

(amperes/ft ) 

1,600 to 6,500 

(150 to 600) 

540 to 2,200 

(50 to 200) 
P.8 

B. Emissions and Controls 

Hexavalent chromium is emitted during the chromium electroplating 

process in the form of a visible yellow mist. The mist is composed of 

entrained chromic acid droplets that form when the hydrogen and oxygen gas 

is released from the surface of the plating solution. The hydrogen gas is 

generated at the cathode while oxygen is liberated at the anode. 

Factors affecting the amount of mist generated from plating tanks 

include the amount of current applied, the amount of surface area plated, 

the amount of chromium deposited, the duration of plating, and the surface 

area of the tank. Uncontrolled emission factors that can be applied to 

chromic acid consumption have been developed by EPA for both hard and 

decorative plating and are presented in Table 2. The factors are based on 

results of EPA source tests at one hard plating facility and one 

decorative plating facility. 

The plating operations tested were representative of a large job shop 

performing hard chromium plating of industrial rolls and a large captive 

shop performing decorative chromium plating of automobile bumpers. 

Although these two operations do not characterize the chromium 

electroplating source category in every respect, they are representative 

of other plating operations in terms of the processes and types of 

emission controls. The emission capture systems at both plants were 

effective in withdrawing mist from the plating area. The decorative 

plating tank contained a fume suppressant to inhibit misting, which is 

common practice for about 90 percent of decorative plating operations. 

Emissions from both plating operations were controlled by multiple 

packed-bed scrubbers. ' 

There are several methods used to reduce chromium emissions from 

chromium electroplating operations. One method used by many decorative 

platers involves adding chemical fume suppressants to the plating 

solution. Although there are different types, most fume suppressants 

generally contain a surfactant that reduces the surface tension of the 

plating solution. Thus, the hydrogen and oxygen gases are released 

without forming the chromic acid bubbles that cause misting. In addition, 
V P.9 

TABLE 2. UNCONTROLLED EMISSION FACTORS USED TO ESTIMATE EMISSIONS 

FROM CHROMIUM ELECTROPLATING OPERATIONS 

Type of 

operation 

Emission factor, 

kg Cr + V 

kg Cr03 used Basis 

Hard 

Decorative 

0.0094 

0.00024a 

EPA source test at Carolina 

Plating—Roll Division plant in 

Greenville, South Carolina. 

EPA source test at C. S. Ohm 

Manufacturing Company plant in 

Sterling Heights, Michigan. 

'Based on the assumption that the fume suppressant used during the test 

controlled 80 percent of the misting. 
P.10 

some fume suppressants also create a layer of foam on the surface of the 

plating solution, which aids in inhibiting misting. Chemical 

manufacturers state that proper use of fume suppressants appear to be 

quite effective for reducing misting, but there are no test data available 

to substantiate this claim." 

Another method of reducing chromium emissions involves the application 

of exhaust systems to the plating tanks and the treatment of the resultant 

exhaust gases by a control device. Two types of control devices are 

typically used: impingement-type mist eliminators and packed-bed wet 

scrubbers. The mist eliminators are equipped with baffles that 

continually change the direction of the gas flow. This promotes the 

impingement of droplets of mist entrained in the exhaust gas on the 

baffles. The collected mist is discharged either into a holding tank or 

directly back into the plating tank. Control device vendors estimate 

removal efficiencies to be 80 to 85 percent for impingement mist 

eliminators. Test data provided by the Naval Energy and Environmental 

Support Activity (NEESA) Group indicate that 96 percent removal efficiency 

was being achieved by a mist eliminator controlling emissions at the 

Norfolk Naval Shipyard. 

In packed-bed scrubbers, the exhaust gases are saturated with water 

and then passed through one or more beds of packing material, the beds are 

several inches and up and are continuously wetted or sprayed. Typically, 

the scrubbers used in this source category contain one or two packed 

beds. Any mist or fume entrained in the exhaust gas impinge on the 

packing and is washed away by the scrubbing liquid. Control device 

vendors estimate removal efficiencies to be 95 to 99 percent for these 

devices.1 Actual EPA source tests conducted across a double packed-bed 

scrubber controlling emissions at the Carolina Plating—Roll Division 

plant indicated that 95 percent removal efficiency was being achieved. 

Test data provided by the NEESA Group indicate that 92 percent removal 

efficiency was being achieved by a single packed-bed scrubber controlling 

emissions at the Long Beach Naval Shipyard. 
P.11 

C. Potential for Improved Control 

There appears to be significant potential for improved control in this 

source category. Although no statistical data are available, it is 

estimated that emissions from about 50 percent of the hard platers and 

about 10 percent of the decorative platers currently are uncontrolled. ' Information obtained from almost 60 plants support this 

assumption, which is based on estimates from control device vendors and 

fume suppressant manufacturers. 

Fume suppressants may be used to reduce hexavalent chromium emissions 

from decorative plating operations that are currently uncontrolled. The 

achievable control efficiency is conservatively assumed to be 80 percent. 

The bases for this assumption were observations at several plants, which 

demonstrated that typically fume suppressants appear to be added according 

to the operator's discretion or judgment rather than a systematic schedule 

or plan. Although fume suppressants also are available for use in hard 

chromium plating operations, hard platers have cited problems with 

electrical sparking and "pitted" surface finishes when these chemicals are 

used in the plating solutions. 

Add-on control devices may be used to reduce hexavalent chromium 

emissions from either hard or decorative plating operations. The capture 

efficiency of a well-designed and -operated ventilation system is 

estimated to approach 100 percent. Achievable control efficiencies are 

conservatively assumed to be 85 percent for impingement mist eliminators 

and 95 percent for packed-bed scrubbers. 

Estimates of costs and emission reductions are presented in Table 3 

for different types of emission controls applied to each of the four model 

plants used to estimate maximum lifetime risks (see Section D-2). The 

model plants are representative of different sizes (small and large) and 

types (hard and decorative). Although the emission reductions achievable 

by the controls may be subject to question, the actual values are probably 

no lower than those listed in Table 3. 
P.12 

TABLE 3. EMISSION REDUCTIONS AND ANNUALIZED COST OF CONTROL 

FOR FOUR MODEL CHROMIUM ELECTROPLATING OPERATIONS 

Item 

Model plant 

B 

Type of plating operation Small 

hard 

Large 

hard 

Small 

decorative 

Large 

decorative 

Uncontrolled emission factor, 

kg Cr /kg Cr03 used 

Cr03 consumption, kg/yr 

(lb/yr) 

Uncontrolled emission rate, 

kg Cr+ / yr (lb Cr+ /yr) 

Packed-bed wet scrubber3 

0.0094 

820 

(1,800) 

7.7 

(17) 

0.0094 

9,600 

(21,200) 

90 

(200) 

0.00024 

1,100 

(2,400) 

0.26 

(0.57) 

0.00024 

16,300 

(35,900) 

3.9 

(8.6) 

Achievable emission reduction, 

kg Cr+6/yr (lb Cr+ /yri 

Capital cost of control, $ 

Annualized cost of 

control,0 $/yr 

Impingement mist eliminator 

Achievable emission reduction, 

kg Cr+ /yr (lb Cr+ /yr) 

Capital cost of control, $ 

Annualized cost of control,0 

$/yr 

Chemical fume suppressant 

Achievable emission reduction, 

kg Cr+5/yr (lb Cr+ /yr) 

Capital cost of control, $ 

Annualized cost of control, $/yr 

7.3 

(16) 

10,500 

4,520 

86 

(190) 

35,400 

15,300 

0.25 

(0.55) 

10,500 

4,380 

3.7 

(8.2) 

43,300 

19,400 

6.5 

(14) 

2,690 

960 

77 

(170) 

8,500 

2,580 

0.22 

(0.49) 

2,690 

1,020 

3.3 

(7.3) 

9,400 

3,540 

N/A 

N/A 

N/A 

N/A 

N/A 

N/A 

0.21 

(0.46) 

0 

1,830 

3.1 

(6.8) 

0 

26,600 

N/A = not applicable. 

^Packed-bed scrubber with two layers of packing to control emissions. 

bDoes not include cost of connecting existing ventilation system to 

control device. 

cDoes not include cost of wastewater treatment. 
P.13 

D. Risk Assessment Inputs 

Estimates of annual incidence and maximum lifetime individual risk 

associated with the emissions of hexavalent chromium from the chromium 

plating source category were calculated using EPA's Human Exposure Model 

(HEM). Inputs to the model include plant locations, estimated emission 

rates, and stack discharge parameters (e.g., gas velocity, temperature, 

stack height, etc.). Because of the large number and diversity of plants 

within this source category, inputs to the HEM were not obtained for the 

individual plants. Instead, model plants were developed using industry 

data and were sited according to the methods described below. A detailed 

description of the methodology used to develop health risk assessment 

inputs for this source category is presented in a separate memorandum 

(B. Duletsky, MRI, to A. Vervaert, EPA:ISB, July 31, 1985. Risk 

1 9 

assessment inputs for chromium electroplating source category.) 

1. Annual incidence. The risk assessment inputs used for calculating 

nationwide incidence are presented in Table 4. Inputs were developed for 

two model plants, one representative of hard platers and one 

representative of decorative platers. It was estimated that hard platers 

account for about 7,300 of the estimated 9,700 plants involved in chromium 

plating, while decorative platers account for about 2,400 plants. The 

estimate is based on information on nationwide chromic acid consumption 

that indicates that 75 percent of the chromic acid consumed by platers is 

consumed by hard platers and 25 percent is consumed by decorative 

platers. The emission rates for the model plants were calculated based 

on the uncontrolled emission factors presented in Table 2, the previously 

cited information on chromic acid consumption, and estimates of the level 

of emission control currently in place within the source category. For 

the hard platers, it is assumed that 50 percent are controlled to 

90 percent based on the use of mist eliminators and scrubbers, and that 

the balance are uncontrolled. In the case of decorative platers, it is 

assumed that 90 percent are controlled to 80 percent and that 10 percent 

are uncontrolled. The 80 percent control level is a conservative estimate 

based on the use of fume suppressants that inhibit emissions. The stack 
r P.14 

TABLE 4. RISK ASSESSMENT INPUTS FOR CALCULATING ANNUAL INCIDENCE DUE 

TO HEXAVALENT CHROMIUM EMISSIONS FROM T^| CHROMIUM 

ELECTROPLATING SOURCE CATEGORY 

Plant name/location: 

Type of source: 

Emission rates, kg/yr: 

Total Cr 

Hexavalent Cr 

Discharge parameters: 

Stack height, m 

Vertical area, m 

Vent type 

Stack diameter, m 

Gas exit velocity, m/s 

Gas temperature, °K 

Hard chromium plating 

model plant to be 

applied at 7,300 

locations, distributed according 

to population 

density. 

H (stack) 

Decorative chromium 

plating model plant 

to be applied at 

2,400 locations, 

distributed according to population 

density. 

H (stack) 

7.7 

7.7 

10 

50 

0 (vertical stack) 

0.5 

15 

300 

0.1 

0.1 

10 

50 

0 (vertical 

0.5 

15 

300 

stack) 

10 
P.15 

discharge parameters reflect typical values obtained from information 

gathered on numerous platers. 

In calculating the aggregate annual incidence, the model hard plating 

plant was distributed among 7,300 sites and the model decorative plating 

plant was distributed among 2,400 sites. The plants were sited according 

to population density, which is a reasonable method of distribution 

because chromium electroplating operations are used by many different 

industries and are usually located in more populated industrial areas. The 

annual incidence of cancer resulting from hexavalent chromium emissions 

2 1 

from chromium electroplating operations is 32 statistical lives. 

2. Maximum lifetime risk. The risk assessment inputs used for 

calculating maximum lifetime risk are presented in Table 5. Four model 

plants were used to represent the following general subcategories of 

chromium platers: small hard platers, large hard platers, small 

decorative platers, and large decorative platers. Chromic acid 

consumption and stack parameters for the four model plants were based on 

data provided by four actual plating plants. The model plants were sited 

at the location of a fifth plating plant in a commercial/residential area 

near Detroit, Michigan. This location is representative of the types of 

areas in which many plating plants are located. 

Although each of the four actual plants has air pollution control 

devices in place, all emissions from the model plants were assumed to be 

uncontrolled for the purpose of assessing maximum lifetime risk. Emission 

rates were calculated using the chromic acid consumption for each plant 

and the factors for uncontrolled emissions listed in Table 2. 

The annual incidence and maximum lifetime risks attributed to uncontrolled hexavalent chromium emissions from these model plants are listed 

in Table 6. As shown on the table, the maximum risk of 8.2 xlO" is due 

to emissions from the large hard plater. The maximum lifetime risks due 

to emissions from the same model plants located in more densely populated 

areas (New York and Los Angeles) were also estimated and are about two 

4 

times greater than the risks listed in Table 6 and exceed 1.0 xlO . 

11 
P.16 

TABLE 5. RISK ASSESSMENT INPUTS FOR CALCULATING MAXIMUM LIFETIME RISK 

DUE TO HEXAVALENT CHROMIUM EMISSIONS FROM THE 

CHROMIUM ELECTROPLATING SOURCE CATEGORY 

Model planta: 

Type of plating 

operation: 

Chromic acid usage, kg/yr: 

Total tank surface area, m : 

Type of source: 

Uncontrolled emission rates, 

kg/yr: 

Total Cr 

Hexavalent Cr 

Discharge parameters: 

Stack height, m 

Vertical area, m 

Vent type 

Stack diameter, m 

Gas exit velocity, m/s 

Gas temperature, °K 

Small 

hard 

816 

4.6 

H (stack) 

7'7h 7.7b 

7.3 

50 

0 (vertical) 

0.61 

9.7 

300 

Large 

hard 

9,607 

18.9 

H (stack) 

90.3b 

90.3b 

23 

250 

0 (vertical) 

1.3 

7.1 

294 

Small 

decorative 

1,089 

5.6 

(H stack) 

0.26c 

0.26c 

7.9 

50 

0 (vertical) 

0.61 

10.1 

294 

Large 

decorative 

16,330 

22.3 

(H stack) 

3.9C 

3.9C 

25 

250 

0 (vertical) 

1.6 

7.1 

294 

aFor the purpose of determining maximum lifetime risk, each plant is to be 

located at the site of an existing plant in the Detroit area (UTM 

zone 17; 3, 35, 122 E; 47, 02, 244 N). +6 

DBased on an uncontrolled emission factor of 0.0094 kg Cr /kg Cr03. 

(Ref.: EPA Source Test at Carolina Plating—Roll Division6plant.) 

cBased on an uncontrolled emission factor of 0.00024 kg Cr /kg Cr03, 

which assumes an 80 percent control efficiency for the fume suppressant 

used during the EPA source test. (Ref: EPA Source Test at C. S. Ohm 

Manufacturing Company plant.) 

12 
P.17 

TABLE 6. RISKS ASSOCIATED WITH EXPOSURE TO UNCONTROLLED HEXAVALEKT 

CHROMIUM EMISSIONS FROM MODEL CHROMIUM ELECTROPLATING OPERATIONS 

Model planta 

Small hard 

Large hard 

Small decorative 

Large decorative0 

Annual inci 

0.003 

0.026 

0.0001 

0.001 

dence 

Maximum lifetime 

risk 

4.1 xlO'5 

8.2 xlO"5 

1.3 xlO"6 

2.8 xlO-5 

Model plants were sited at the location of an existing plating plant in 

.Warren, Michigan, a representative commercial/residential area. 

"Risks are scaled up by a factor of 0.26/0.05 (estimated uncontrolled 

emissions/estimated emissions when using a fume suppressant). 

cRisks are scaled up by a factor of 3.9/0.51 (estimated uncontrolled 

emissions/estimated emissions when using a fume suppressant). 

13 
P.18 

E. References 

1. Radian Corporation. Addendum to "Estimates of Population Exposure to 

Ambient Chromium Emissions" October 1983 Final Report. Prepared for 

U. S. Environmental Protection Agency. Research Triangle Park, North 

Carolina. July 1984. p. 20. 

2. Memorandum from Duletsky, B., MRI, to Vervaert, A., EPA/ISB. 

July 31, 1985. Risk assessment inputs for chromium electroplating 

source category. Attachment A. 

3. Reference 1, pp. 14-16. 

4. Reference 1, p. 16. 

5. Dabpernell, G. Chromium. In: Modern Electroplating, Lowenheim, 

F. A. (ed.). New York, John Wiley and Sons, Inc. pp. 100-151. 

6. Memorandum from Duletsky, B., MRI, to Vervaert, A., EPA/ISB. May 20, 

1985. Trip report for Carolina Plating—Roll Division, Greenville, 

South Carolina. 

7. Memorandum from Duletsky, B., MRI, to Vervaert, A., EPA/ISB. 

April 26, 1985. Trip report for C. S. Ohm Manufacturing Company, 

Sterling Heights, Michigan. 

8. Reference 2, pp. 4-5. 

9. Telecon. Duletsky, B., MRI, with Dargis, R., McGean-Rohco. July 22, 

1985. Information about fume suppressants. 

10. Telecon. Duletsky, B., MRI, with Stanton, D., Dual! Industries. 

July 29, 1985. Information about mist eliminators. 

11. Source Emission Testing of the Building 195 Plating Shop, Norfolk 

Naval Shipyard, Portsmouth, Virginia, 11-18 March 1985. Report 

No. NEESA 2-124. May 1985. p. 25. 

12. Telecon. Duletsky, B., MRI, with Woll, R., Air Plastics, 

Incorporated. April 5, 1985. Information about scrubber control 

systems. 

13. Entroy Environmentalists, Inc. Emission Test Report for Carolina 

Plating—Roll Division, Greenville, South Carolina. Second Draft. 

Prepared for U. S. Environmental Protection Agency. Research 

Triangle Park, North Carolina. October 1985. 

14. Source Emission Testing and Industrial Ventilation Survey of Building 

210 Plating Shop at Long Beach Naval Shipyard, Long Beach, 

California, 7 May - 2 June 1984. Report No. NEESA 2-119. 

September 1984. p. 44. 

14 
P.19 

15. Telecon. Duletsky, B., MRI, with Bumsha, M&T Chemicals, Inc. 

July 29, 1985. Information about fume suppressants. 

16. Memorandum from Duletsky, B., MRI, to Vervaert, A., EPA/ISB. 

April 26, 1985. Trip report for General Plating, Inc., Detroit, 

Michigan. 

17. Telecon. Duletsky, B., MRI, with Chessin, H., M&T Chemicals, Inc. 

July 12, 1985. Information about factors that affect emissions from 

chromium electroplating processes. 

18. Memorandum from Duletsky, B., MRI, to Vervaert, A., EPA/ISB. 

August 21, 1985. Costs for control options—chromium electroplating. 

19. Reference 2, pp. 7-8. 

20. Report to the Scientific Review Panel on Chromium. California Air 

Resources Board and the California Department of Health Services. 

March 1985. p. 1-5. 

21. Memorandum and attachments from Patrick, D., EPA/PAB, to Cuffe, S., 

EPA/ISB. November 13, 1985. Final risk analyses for hexavalent 

chromium for Phase I studies. 

22. Reference 2, p. 2. 

23. Reference 2, p. 3. 

15