United States Solid Waste and Pesticides and EPA530-R-92-010
Environmental Protection Emergency Response Toxic Substances PB92-162 551
Agency (OS-305) (TS-799) April 1992
£EPA Preliminary Use and
Substitutes Analysis of
Lead and Cadmium in
Products in Municipal
Solid Waste
Printed on Recycled Paper
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PRELIMINARY USE AND SUBSTITUTES
ANALYSIS FOR LEAD AND CADMIUM IN
PRODUCTS IN MUNICIPAL SOLID WASTE
Prepared by:
Economics and Technology Division
Office of Pollution Prevention and Toxics
U.S. Environmental Protection Agency
Prepared for:
Office of Solid Waste
U.S. Environmental Protection Agency
January 27, 1992
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CERTIFICATION
ICF Incorporated certifies that the ink used to
print this document is completely free of lead
and/or cadmium. The Xerox* toner and developer
products used to produce this report do not
intentionally contain lead and/or cadmium nor do
they contain these elements as impurities or
byproducts.
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TABLE OF CONTENTS
SUMMARY REPORT x
I. INTRODUCTION 1
A. Limitations '.- 3
B. References 4
II. PLASTICS 5
A. Overview of Plastics Industry 6
B. Additives Used in the Processing of Plastics 7
C. Consumption of Lead- and Cadmium-containing Products in
Plastics 20
D. Potential Substitutes for Lead- and Cadmium-containing
Additives for Plastics 27
E. References 44
III. PIGMENTS 46
A. Overview of the Pigment Industry 46
B. Uses of Lead- and Cadmium-containing Pigments 46
C. Consumption of Lead and Cadmium in Pigments 46
D. Potential Substitutes of Lead- and Cadmium-containing
Pigments 46
E. References 53
IV. SOLDER 54
A. Overview of the Soldering Industry 54
B. Solder Use Areas 55
C. Consumption of Lead and Cadmium in Solder 61
D. Potential Substitutes for Lead- and Cadmium-containing
Solders 65
E. References 78
V. LEAD-ACID BATTERIES 81
Reference 82
VI. NICKEL-CADMIUM BATTERIES 83
A. Overview of the Battery Industry 83
B. Use of Nickel-cadmium Batteries 84
C. Consumption of Cadmium in Nickel-cadmium Batteries 85
D. Potential Substitutes for Nickel-cadmium Batteries 87
E. Limitations on Substitution 91
F. References 94
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TABLE OF CONTENTS
(Continued)
Page
VII. GLASS AND CERAMIC PRODUCTS 95
A. Overview of Glass/Ceramic Products 95
B. Uses of Lead and Cadmium in Glass/Ceramic Products ....... 95
C. Consumption of Lead and Cadmium in Glass/Ceramic Products . . 103
D. Potential Substitutes for Lead and Cadmium in
Glass/Ceramic Products 106
E. References 113
VIII. BRASS AND BRONZE PRODUCTS 115
A. Overview of Copper Alloys Industry 115
B. Consumption of Lead in Brass and Bronze 116
C. Potential Substitutes for Lead in Brass and Bronze 117
D. References 122
IX. CADMIUM-PLATED PRODUCTS 123
A. Overview of the Plating Industry 123
B. Consumption of Cadmium in Electroplating 125
C. Potential Substitutes for Cadmium in Metallic Coatings .... 125
D. References 131
X. COLLAPSIBLE TUBES T32
A. Overview of Tube Industry 132
B. Use of Lead Tubes 132
C. Consumption of Lead in Tubes 132
D. Potential Substitutes for Lead Tubes 132
E. References 136
XI. OTHER PRODUCTS 137
A. Foil Wine Wrappers 137
B. Used Oil 137
C. Rubber (Elastomer) Products 139
D. Printing Inks 146
E. Electric Blankets and Heating Pads 150
F. References 152
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LIST OF TABLES
Page
Table SR-1. Discards of Lead and Cadmium by Use Area in MSW in
1986
xi
Table SR-2. Lead and Cadmium Pigments and Potential Substitutes xiv
Table SR-3.
Lead- and Cadmium-based Heat Stabilizers and Potential
Substitutes
xv
Table SR-4. Potential Substitute Solders and Processes for Lead-
and Cadmium-Containing Solder for Consumer Electronic,
Consumer Can, and Light Bulb Applications xviii
Table SR-5. Potential Substitutes for Nickel Cadmium Batteries xx
Table SR-6. Potential Substitutes for Lead and Cadmium in Glass
and Ceramics xxiii
Table SR-7. Potential Substitutes for Lead-based Brass and Bronze
Products
XXV
Table SR-8. Potential Substitutes for Cadmium Plating xxvii
Table SR-9.
Table 1.
Table 2.
Table 3.
Table U.
Table 5.
Table 6.
Table 7.
Table 8.
Table 9.
Potential Substitutes for Miscellaneous Products
Containing Lead or Cadmium xxx
Discards of Lead and Cadmium by Use Area in MSW in
1986 2
Representative Thermoplastic and Thermosetting Resins 6
Lead and Cadmium Inorganic Pigments and Their
Performance Properties 12
Representative Cadmium and Lead-based Heat Stabilizers
and Their Properties
Advantages/Disadvantages of Lead-based Heat
Stabilizers
15
17
Current and Declining uses of Lead-based Heat
Stabilizers 18
Advantages/Disadvantages of Cadmium-based Heat
Stabilizers 21
Uses for Cadmium-based Heat Stabilizers 22
Discards of Lead in Pigments for Plastic in MSW 23
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LIST OF TABLES
(Continued)
Paee
Table 10. Discards of Cadmium in Pigments for Plastic in MSW 25
Table 11. Discards of Lead in Stabilizers for PVC in MSW 26
Table 12. Discards of Cadmium in Stabilizers for PVC in MSW 28
Table 13. Potential Substitutes for Lead and Cadmium Pigments
and Their Performance Properties 31
Table 14. Costs: Lead- and Cadmium-based Pigments and
Potential Substitutes 32
Table 15. Potential Substitutes for Lead-based Heat Stabilizers
in Rigid PVC Products 35
Table 16. Potential Substitutes for Lead-based Heat Stabilizers
in Flexible PVC Products 38
Table 17. Potential Substitutes for Cadmium-based Heat
Stabilizers in Rigid PVC Products 40
Table 18. Potential Substitutes for Cadmium^based Heat
Stabilizers in Flexible PVC Products 41
Table 19. Costs of Lead, Cadmium, and Potential Substitute Heat
Stabilizers 42
Table 20. Discards of Lead in Pigments for Plastic in MSW 47
Table 21. Discards of Lead in Pigments for Rubber Products in
MSW 48
Table 22. Discards of Lead in Pigments for Ink and Miscellaneous
Products in MSW 49
Table 23. Discards of Cadmium in Pigments for Plastic in MSW 50
Table 24. Discards of Cadmium in Pigments for Glass, Ceramics,
and Miscellaneous Products in MSW 51
Table 25. Discards of Cadmium in Pigments for Rubber Products in
MSW 52
Table 26. Discards of Lead in Solder in MSW 63
Table 27. Advantages and Disadvantages of Potential Substitute
Solders for Consumer Electronic Applications 67
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LIST OF TABLES
(Continued)
Page
Table 28. Advantages and Disadvantages of Substitute Processes
and Solders for Consumer Can Applications 74
Table 29. Advantages and Disadvantages of Potential Substitute
Solders for Light Bulb Applications 76
Table 30. Discards of Cadmium in Nickel-cadmium Batteries in
MSW 86
Table 31. Advantages and Disadvantages of Substitute Batteries
for Nickel-cadmium Batteries 93
Table 32. Properties Lead Imparts to Glass/Ceramic Products 97
Table 33. Discards of Lead in Glass and Ceramics in MSW 104
Table 34. Discards of Cadmium in Pigments* for Glass, Ceramics
and Miscellaneous Products in MSW 105
Table 35. Potential Substitutes for Lead and Cadmium in Glass
and Ceramics 107
Table 36. Discards of Lead in Brass and Bronze in MSW 118
Table 37. Potential Substitutes for Lead-based Brass and Bronze
Products 120
Table 38. Cost: Lead-based Brass and Bronze Products and Their
Potential Substitutes 121
Table 39. Discards of Cadmium in Plated Parts for Home
Appliances and Electronics in MSW 126
Table 40. Characteristics of Potential Substitutes for Cadmium
Plating 128
Table 41. Costs of Cadmium Plating and Potential Substitutes 129
Table 42. Discards of Lead in Collapsible Tubes in MSW 133
Table 43. Potential Substitutes for Collapsible Lead Tubes 134
Table 44. Discards of Lead in Foil Wine Wrappers in MSW 138
Table 45. Discards of Lead in Used Oil in MSW 140
Table 46. Potential Substitutes for Alkyl lead Anti-knock Agents
Used as Oil Lubricants 141
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LIST OF TABLES
(Continued)
Table 47. Discards of Lead Pigments Used in Rubber Products in
MSW 143
Table 48. Discards of Cadmium in Pigments Used for Rubber
Products in MSW 144
Table 49. Potential Substitutes for Representative Lead- and
Cadmium-based Vulcanizing Agents 146
Table 50. Discards of Lead in Printing Inks in MSW 148
Table 51. Advantages and Disadvantages of Potential Substitute
Ink Pigments for Lead-containing Printing Ink
Pigments 149
Table 52. Discards of Cadmium in Electric- Blankets in MSW 151
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LIST OF FIGURES
Paee
Figure 1. Comparison of Through-Hole and Surface Mount
Technologies
Figure 2. Melting Temperature of Common Soldering Alloys 69
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SUMMARY REPORT
The use of lead- and cadmium-containing articles that ultimately are
disposed of in municipal solid waste (MSW) facilities is the focus of a joint
project by the Office of Toxic Substances and the Office of Solid Waste.
Disposal of lead- and cadmium-containing products is a concern because
incineration of these items concentrates the metals in the ash residue which,
when landfilled, may lead to groundwater contamination.
The Pollution Prevention Act of 1990, passed by Congress on October 27,
1990, asserts that, "pollution should be prevented or reduced at the source
wherever feasible (EPA 1990)." This report identifies lead- and cadmium-
containing products that are disposed of in MSW, and provides information
regarding potential substitutes for these metals in various applications. The
identification of technically feasible substitutes for lead and cadmium in
products found in MSW can be an important preliminary step towards pollution
prevention.
In 1989, EPA issued a report entitled "Characterization of Products
Containing Lead and Cadmium- in Municipal Solid Waste in the United States,
1970 to 2000." The current report examines technologically feasible lead and
cadmium substitutes for each of the products identified in the 1989 report.
To provide perspective on the sources of lead and cadmium in MSW, Table SR-1
provides estimates for 1986 discards of both metals in each product use area.
A full copy and/or the Summary Report of this document, "Preliminary Use and
Substitutes Analysis for Lead and Cadmium in Products in Municipal Solid
Waste," may be obtained by calling the EPA Resource Conservation and Recovery
Act (RCRA) hotline number: (800) 424-9346.
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Table SR-1. Discards of Lead and Cadmium by Use Area in MSW in 1986
Product Area
Lead Acid Batteries
Plastics
Pigments3
Solder
Nickel/Cadmium Batteries
Glass and Ceramic Products
Brass and Bronze Products
Plated Products
Collapsible Tubes
Rubber Products
Other Products6
Lead Discards
(tons)
138,043
3,174
1,131
8,369
- 0
60,714
321
0
639
70
671
Cadmium Discards
( tons )
0
564
70
0
927
29
0
185
0
6
1
a Discards of pigments do not include pigments consumed in plastics,
glass/ceramic products, or rubber products. These discards are
covered in the sections on plastics, glass/ceramic products, and
rubber products.
b Other products include used oil, foil wine wrappers, electric
blankets and heating pads, and television and radio chassis. 279
tons of lead were discarded as part of television and radio chassis,
but future discards are expected to be zero due to a change in
technology which has discontinued the use of lead in these products.
Sources: EPA 1989, Franklin 1990.
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LIMITATIONS
This report should be considered as a preliminary analysis due to the
limitations of its scope. EPA has not performed primary research to identify
the substitutes for lead and cadmium described in this report. Only
substances identified in published sources or by industry contacts and that
were known or considered to be potential substitutes have been included in
this analysis. Because this report characterizes substitutes for both lead
and cadmium products, lead and cadmium are not considered as substitutes for
each other although this sometimes may be technically feasible. Furthermore,
the substitution in this report is based only on technical feasibility and
does not quantitatively assess economic factors that affect substitution or
the effect of potential substitutes on end products (e.g., different service
lives for substitute products). While some information is provided on the
cost of potential substitute compounds, no economic analysis has been
performed to estimate the impacts of substituting for lead and/or cadmium
products. This report, therefore, is not intended to draw conclusions about
the viability of actual substitution. No economic analysis has been performed
to estimate the impacts of substituting for lead and/or cadmium products.
In addition, toxicities of substitutes are not discussed in this report
and toxicity was not a criterion for identifying potential substitutes. Many
of the classes of chemicals assessed have intrinsic toxicities that would be
of great concern in other parts of the manufacturing processes where there
would be human or environmental exposure to more bio-available forms of the
chemical or chemicals. A more focused, in-depth substitute characterization
for each chemical substitute in each use area would be required to adequately
assess the hazard presented by potential substitutes.
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LEAD AND CADMIUM SUBSTITUTES
The range of consumer products that contain lead and/or cadmium and are
disposed of in MSW facilities is quite broad. The remainder of this report
focuses on potential substitutes for lead-and cadmium-containing products in
each of the following areas:
plastics (pigments and heat stabilizers);
pigments ;
solder;
lead-acid batteries;
nickel-cadmium batteries;
glass and ceramic products;
brass and bronze products;
cadmium-plated products;
collapsible tubes; and
other products (foil wine wrappers, used
oil, rubber products, and electric
blankets/heating pads).
Plastics
Lead- and cadmium-containing additives are used in plastics as both
pigments and heat stabilizers. Table SR-2 lists lead and cadmium pigments and
their possible substitutes. Table SR-3 lists lead- and cadmium-based heat
stabilizers and their potential substitutes.
For many of the lead- and cadmium-based colorants, potential substitutes
that provide similar hues have been identified. However, for specific
applications hue may not be the most important factor influencing the choice
of a pigment. For example, while some organic pigments match the hue of
cadmium pigments, individual substitute pigments may not be adequate in terms
of brilliance, lightfastness, or high-temperature stability for some
applications. Furthermore, the costs of these substitutes may be
Pigments containing lead and/or cadmium are used in paint, ink, paper,
rubber, glass, and plastic products. The discussion of pigments is summarized
separately, but the majority of information on pigments is contained in the
plastics section.
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Table SR-2. Lead and Cadmium Pigments and Potential Substitutes
Hue*
Lead and Cad*ium Pigments
Potential Substitutes
Performance
Yellow
Lead chromate
Cadmium sulfide
CadmiuM sulfide and Zinc
Nickel titanium (NiTi)(inorganic)
Honoazo (organic)
Pyrazolone derivative (dye)
General suitability, but greatly
reduced tinting strength
Suitable for low density polyethylene,
and polystyrene. Not suitable for PVC.
Suitable for polymethyl methacrylate,
unplasticized PVC, and polystyrene.
Red
Lead molybdate
Cadmium/sulfide selenide
Iron oxide (inorganic)
Honoazo naphthol (organic)
Azo dye (dye)
Ouinacridone (organic)
Perylene (organic)
General suitability
Caution is needed in the case of high
density polyethylene articles
sensitive to distortion.
Suitable for polymethyl methacrylate,
unplasticized PVC, and polystyrene.
Suitable for polystyrene, PVC, low
density polyethylene. Caution' is needed
in high density polyethylene articles
sensitive to distortion.
Suitable for polystyrene, PVC, and low
density polyethylene. Caution is needed
in high density polyethylene articles
sensitive to distortion.
* Potential substitutes are based on similar hue or color (i.e., any of the substitutes in a color group is assumed to be able to substitute for any
lead- or cadmium-based pigment with the same hue). In some cases this may not be the most important characteristic (e.g., heat stability may be an
important factor).
b For dyes, lightfastness and heat stability depend on the plastic to be colored.
Sources: Plastic Additives Handbook 1987. Bayer Nobay 1989. and BASF 1989.
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Table SR-3. Lead- and Cadmium-based Heat Stabilizers and Potential Substitutes
Stabilizer
Potential Substitutes
Performance Comments
Lead Stabilizers
Tribasic lead sulfate
Dibasic lead phosphite
Dibasic lead ph thaiate
Dibasic lead stearate
Normal lead stearate
Dibasic lead carbonate
Organotin stabilizers
Barium/zinc stabilizers
letIone*
Suitable for a wide range of rigid and
flexible PVC applications although different
organotin stabilizers have different areas
of sui tabiIi ty.
Suitable for flexible PVC applications such
as shoes, sandals and soles.
Technically feasible substitute for cable
insulation and jacketing but not as a one-
for-one substitute for lead-based heat
stabilizers.
CadMiiM Stabilizers
Bariu*ycadmiuM decanoate
(and other fatty acid salts)
BariuM/cadmiuM alkyl phenols
Bari UN/cadmium benzoates
Zinc/calcium stabilizers
Organotin stabilizers
Barium/zinc stabilizers
Suitable for a wide range of flexible PVC
applications.
Suitable for a wide range of rigid and
flexible PVC applications although different
organotin stabilizers have different areas
of suitability.
Suitable for a wide range of rigid and
flexible PVC applications
PVC = polyvinyl chloride.
* Teflon* is a different class of substitute in that it would replace the end-product, PVC coatings, used for wire and cable insulation.
Sources: Argus 1989a. 1969b, 1989c; and Bedford 1989.
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significantly higher than their lead- and cadmium-containing counterparts.
Although the majority of companies no longer supply lead-based pigments,
cadmium pigments are still produced because their performance characteristics
are difficult to reproduce.
Potential substitute products that can replace lead- and cadmium-
containing heat stabilizer products continue to be investigated due to the
toxicity of lead and cadmium compounds and the availability of an increasing
number of technically superior alternate products. Lead and cadmium heat
stabilizers have seen widespread use because of their relatively low cost
compared to newer substitute products.
The replacement of lead-based heat stabilizers in electrical cable
insulation and jacketing (power wiring, telephone cable, and cords and
connectors for appliances and other consumer items) has been difficult due ta
the critical properties of weathering, humidity resistance, and thinness of
the jacket that lead imparts. Potential substitutes for cadmium-containing
stabilizers have been identified.
Pigments
A pigment is defined as a substance that imparts color to other
materials. Pigments are normally insoluble in the material in which they are
dispersed and usually are classified as either organic or inorganic.
Pigments are used in a wide variety of products: paint, ink, plastic,
paper, rubber, and glass. The discussion of pigments found in the Plastics
section above is applicable to lead- and cadmium-containing pigment
substitution in general.
Solder
Solder is used in a variety of products to form both electrical and
structural bonds between various types of materials. The most common use of
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solder is to attach electrical components to printed circuit boards (Arconium
1989). Tin/lead soldering alloy is the most common soldering alloy currently
in use (Kapp 1989). The chief reason tin/lead solder is used to produce
consumer electronics is low cost (Talco 1989). Products containing solder
that enter the municipal waste stream include consumer electronics, cans, and
light bulbs.
Cadmium-containing solder is not used commonly to manufacture consumer
electronics. Manufacturers avoid the use of cadmium because of health-related
concerns including the generation of poisonous fumes during the soldering
operation (IPC 1989a, Keeler 1987, Indium 1989c). Cadmium-containing solder
also is not used in the manufacture of cans, but has been used in the past in
light bulb manufacturing (NFPA 1989, Sylvania 1989b).
Four types of potential substitute solder alloys have been identified
for consumer electronics applications (see Table SR-4). All of these solders
employ exotic metals making them much more expensive than tin/lead solder.
The characteristics of the potential substitute solder alloys differ from
tin/lead solder in terms of melting temperature, required flux type, ability
to wet the surfaces to be soldered, and bond strength.
Lead-acid Batteries
Batteries are classified as primary and secondary cells. Primary
battery cells are also known as "fuel cells" because the active chemicals are
used in an irreversible reaction. This type of cell typically is disposed of
after use. By contrast, secondary battery cells may be recharged because
their chemistry is based on a highly reversible reaction. After charging,
however, the materials do not return exactly to their previous (charged)
state, limiting the number of times the secondary battery can be reused.
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Table SR-4. Potential Substitute Solders and Processes for Lead- and Cadmium-containing Solder in Consumer Electronic, Consumer Can,
and Light Bulb Applications
Application Area
Potential Substitutes
Performance Comments
Consumer Electronics
Bismuth/tin solder
Tin/silver solder
Indium/tin solder
Indium/silver solder
Suited to surface mount assembly technology. Some bismuth alloys may
have unacceptably low melting temperatures for use in consumer
products.
Can be used to solder silver-plated base metal without significantly
solubilizing the silver. Less ductile than indium and bismuth solder
alloys. Higher cost than tin/lead solder.
Suited to surface mount assembly technology. Compatible with gold and
other precious metals. Lou melting point not suitable for high
temperature applications. As much as 20 times the cost of tin/lead
solder.
Suited to surface mount assembly technology. Compatible with gold and
other precious metals. Low melting point not suitable for high
temperature applications. As much as 20 times the cost of tin/lead
solder.
Consumer Can
Light Bulb
Crimping process*
Welding process*
Tin solder
Indium-based solder
Eliminates the need for solder.
Eliminates the need for solder.
Eliminates the possibility of lead leaching into canned food products.
Nay be used in non-food cans. More expensive than tin/lead solder.
More expensive than tin/lead solder. Oxidizes when used in light bulb
manufacturing process. Tin/zinc solderOoes not flow as well as tin/lead
solder.
* Welding and crimping processes are in a different class of substitutes in that they would replace the soldering process used for consumer cans.
Sources: AOL 1990; CHI 1989a, 1989b; Indium 1989b. 1989c; IPC 1989b; Kapp 1989; Keeler 1987; Nanko 1979; NFPA 1989b; Sylvania 1989b, 1989c.
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Lead-acid batteries are currently the most commonly used type of
rechargeable battery. These batteries are used for starting, ignition, and
lighting in virtually all motorized vehicles, and are used in other
applications where rechargeable portable power is desired (e.g., consumer
electronics such as power tools). Lead-acid batteries continue to be widely
used because, based on performance and cost of potential alternatives, no
acceptable substitutes currently exist. Technologies that were examined for
this report include nickel-zinc, nickel-iron, and silver-zinc batteries
(nickel-cadmium batteries are not considered to be substitutes within the
scope of this analysis).
Nickel-zinc batteries have a lower power density than lead-acid
batteries, a limited lifetime, relatively poor reliability, and are two to
three times the cost of an equivalent sized lead-acid battery. Nickel-iron
batteries also have a relatively low power density, as well as poor low-
temperature performance and charge retention. Silver-zinc batteries cost 20-
to 100 times as much as an equivalent sized lead-acid battery. They also have
a limited lifetime and decreased performance at low temperatures (Palmer
1988).
Nickel-cadmium Batteries
Nickel-cadmium (Ni-Cd) batteries are a type of secondary cell often used
in applications that consume large amounts of power (e.g., portable stereos
and photographic strobes). Table SR-5 presents potential substitute batteries
that have been identified. The potential substitutes examined are lithium,
silver-zinc, nickel-zinc, nickel-hydrogen, and primary (alkaline, lithium, and
carbon-zinc) batteries. With the exception of primary batteries, none of
these substitutes have been used much in consumer products because of
technical complications, reduced service life, and high cost. In addition,
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Table SR-5. Potential Substitutes for Nickel Cadmium Batteries
Potential Substitute
Performance Comments
Lithium Battery
Silver-Zinc Battery
Nickel-Zinc Battery
Nickel-Hydrogen Battery
Primary Battery
(alkaline, lithium, and carbon-
zinc)
Less than half the lifetime of
nickel cadmium battery. Sensitive
to abuse.
Less than one-fifth the lifetime of
nickel-cadmium battery.
Less than one-tenth the lifetime o-f
nickel-cadmium battery.
High atmospheric pressure required
in cell.
Not able to be recharged; must be
replaced.
Sources: Yardney 1989a, 1989b; SAFT 1989a; Chemical Business 1989.
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many of these technologies are currently in an embryonic stage of development
and their costs are quite high. As experimentation and development proceeds,
the limitations and the costs of these substitute products may be reduced.
One of the more promising technologies is the rechargeable lithium cell
which is already used to a very limited extent in some consumer applications.
According to one supplier, rechargeable lithium batteries have greater charge
capacity than Ni-Cd batteries of a comparable size (SAFT 1989a, Moli 1989).
However, lithium batteries are currently much more expensive (at least twice
the price) than Ni-Cd batteries and they are more sensitive to abuse such as
overcharging. Advantages of lithium rechargeable batteries include their
light weight, ability to provide energy in sub-freezing temperatures, and very
high efficiency. Possible applications for lithium batteries include portable
cellular phones, lap-top computers, portable radios, and military applications
(Panasonic undated).
Another battery technology currently in use is the silver-zinc system.
This system, which has a high energy density, is used primarily (90 percent of
the time) for military and space applications (Kirk-Othmer 1978, SAFT 1989c) .
There are many limitations that may restrict its use in consumer applications
such as high cost and limited service life.
The nickel-zinc cell is a potential substitute that offers a charge
density greater than that available from nickel-cadmium batteries, but at a
lower cost than silver-zinc. Although its performance is not as high as its
silver-based counterpart, it is also not subject to the wide fluctuations in
price resulting from speculation in precious metals markets.
An additional battery system that currently is found only in exotic
applications (e.g. satellite applications) is the nickel-hydrogen cell. The
hydrogen in the cell is in the gaseous form, and the operating pressure is
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much higher than other cells, ranging from 3-20 times atmospheric pressure, as
compared to 0-3 atmospheres for a nickel-cadmium cell. Because of these high
operating pressures, construction is labor-intensive and very expensive.
Glass and Ceramic Products
The use of lead in glass products is primarily due to its good
performance properties and low cost relative to potential substitutes. As an
intermediate, lead monoxide adds to the brilliance of glass products, and as a
modifier, it lowers the melting temperature, thereby simplifying glass
processing. Lead-containing glass also can shield high energy radiation and
the high refractive index of lead yields excellent properties for optics and
for hand-formed art ware. Cadmium in glass and ceramic products is used as a
pigment in a glaze, as a colorant in the glass itself, or as a phosphor (EPA
1989).
Table SR-6 lists potential substitutes for lead and cadmium in glass and
ceramic products. The potential substitutes for lead- and cadmium-based
glass/ceramic products usually involve switching to alkaline earth metals
(primarily strontium and barium) and zirconium, that are expensive in
comparison to lead and cadmium. The performance properties of the potential
substitutes for lead-based glass/ceramic products lack the refractive indices,
the radiation absorption characteristics, and the ease of processing of lead-
based glass/ceramic products. There are also reports of supply problems with
strontium and zirconium (Corning 1989c).
Brass and Bronze Products
Lead is generally added to brass to improve the free machining
characteristics of the alloy. Lead also may be present as an impurity in some
brass products due to the lead content of scrap materials used in the
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Table SR-6. Potential Substitutes for Lead and Cadmium in Glass and Ceramics
Lead and Cadmium Use
Potential Substitute
Performance Comments
Glass
Television Parts:
Neck and funnel
(28 and 22 percent PbO
respectively)
Faceplate (panel)
(2X PbO)
Leaded Glass:
X-ray shielding
Neon/fluorescent tubing
Light bulb
Optical Glass
Ceramics
Glazes/enamels
PZT/PZLT (68X PbO)
Strontium
Barium
Zirconium
Thicker glass
Strontium/barium
Cerium
Alkaline earth metals
Barium/zinc oxides
zinc, lithium, and barium oxides
Zirconium dioxide
Chrome tin salt
Barium lead titanate
(10X lead)
Quartz
Rochelle Salts
Processing problems, lower durability,
larger quantity required.
Supply problem, marginal cost difference (6
percent higher).
Expensive; increased space requirements and
decreased visual clarity.
Processing problems
*
Under development; processing problems.
Under development; processing problems.
Lower achievable index of refraction than
with lead. Commercially available.
Satisfactory brilliance and alkali
resistance; some application problems.
Color instability.
Not as piezoelectrically efficient; cannot
be used in temperatures over 100°C; 25
percent less expensive.
Not as piezoelectrically efficient; 3-4
times more expensive.
Not effective in humid environment; more
piezoelectrically efficient.
Sources: Blanche 1989; Corning 1989a, 1989b, 1989c, 1989d; Degussa 1989; Piezo Kinetics 1989; Sylvania 1989a.
- xxiii -
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manufacture of brass products. Lead is present, therefore, in virtually all
kinds of brass at least to a small degree. Leaded bronze may contain up to 30
percent lead. The lead is included because it improves workability and
conformability (Copper Development Association 1989) .
Two methods can be used to substitute away from lead in brass and
bronze. Alternative metals can be incorporated with copper to create alloys
with similar properties to lead-containing products, or alternative materials
(e.g., plastics or steel) can be used in the final products.
Table SR-7 identifies the potential substitutes by use area for leaded
brass and bronze products. The choice of potential substitute depends to a.
large extent on the properties that the consumer requires most and which, if
any, properties offered by leaded brass and bronze can be forfeited.
Different substitutes will be chosen if hardness, color, strength, or another
property is critical or must remain constant.' Bearings and fittings made from
unleaded tin bronze and aluminum bronze are already used in heavier load
applications for which leaded bronze is not hard enough. Machinable leaded
brass and bronze used for screw parts and plumbing fixtures can be substituted
by other copper alloys to a large degree. The addition of tellurium,
selenium, or sulfur offers the possibility of improving the machining
characteristics of copper and its alloys without the use of lead (Copper
Development Association 1989, Kirk-Othmer 1978).
Other potential substitutes for leaded brass can replace specific end
products. For example, some plumbing fixtures and valves currently
manufactured with brass or bronze may be replaced by PVC or other plastic
materials, but these materials are not suitable for the bulk of brass and
bronze applications. Machined screws may be replaced by steel screws or
another machinable metal depending on the importance of corrosion resistance.
- xxiv -
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Table SR-7. Potential Substitutes for Lead-based Brass and Bronze Products
Lead Use
Potential Substitutes
Performance Comments
Machined Products
Plumbing Fixtures
Machine Screw Parts
Bushing/Bearing Products
Steel3
PVCa
Tellurium bronze
Selenium bronze
Sulfur bronze
Tin bronze
Aluminum bronze
Manganese bronze
Poor corrosion resistance
Not able to handle all
applications; poor shear
resistance.
Not commercially available;
marginal difference in
mach inab i 1 i ty.
Not commercially available;
marginal difference in
machinability.
Not commercially available;
marginal difference in
machinability.
Harder, requires lubrication.
Harder, requires lubrication.
Harder, requires lubrication.
Steel and PVC .are a different class of potential substitute in that they replace the end-product uses of
brass and bronze instead of the use of lead in brass and bronze.
Sources: Copper Development Association 1989, Nielsen undated, Kirk-Othmer 1978.
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Cadmium Plated Products
Cadmiua plating is used on fabricated steel and cast iron parts and can
be electroplated on plastics or metal in some appliance and consumer
applications. Cadmium is used because it has a combination of properties:
natural lubricity, corrosion resistance to salt water and alkalis, high
deposition rate on application, good solderability and ductility, and a long-
lasting silvery-white luster.
Cadmium plating is used to protect bolts and screws used in marine
V;
applications from corrosion due to prolonged exposure to moisture and salt.
In general, cadmium plated products have a longer service life due to their
corrosion resistance and natural lubricity that help in applications where
mechanical seizures would impair function. Automotive uses such as seat belt
fasteners and brake linings are examples of applications for which these
features are important. Cadmium plated fasteners also are used because their
natural lubricity reduces the torque experienced during fastening, thereby
reducing the potential for fatigue and failure.
Potential substitutes for cadmium in plating operations can be
classified into two groups: (1) alternative materials and technologies for
applications that do not require the properties imparted by cadmium plating
and (2) alternative coatings with similar properties that can be used in place
of cadmium. Table SR-8 contains a list of the potential substitutes for
cadmium in plating operations.
The substitution that has already taken place in the majority of
household applications has used alternative materials. Cadmium plated parts
in washing machines and dishwashers have been replaced to a great degree by
the increased use of plastic construction that does not require cadmium plated
bolts to hold the frames together (EPA 1989).
- xxvi -
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Table SR-8. Potential Substitutes for Cadmium Plating
Cadmium Use
Potential Substitutes
Performance
Electronics (chassis)
Resinous printed circuit boards8
Substitution already occurring;
superior technology.
Fasteners (nuts, bolts)
Plastic construction3
Zinc plating
Tin plating
Gold plating
Chrome plating
Substitution already occurred in
consumer household appliances,
but not possible in most cases.
Lower corrosion resistance, loss
of lubricity, loss of
solderability.
Good solderability, poor
corrosion resistance.
Good corrosion resistance, very
expensive, poor wear resistance.
Good wear properties, better
corrosion resistance for acids,
lower corrosion resistance for
salts and neutral pH.
8 Plastic construction and resinous printed circuit boards are a different class of substitute in that they
eliminate the need for the end-product use of cadmium plated parts.
Sources: AESF 1989, Cadmium Council 1989. Iron Age 1980, Kirk-Othmer 1978.
- xxvii -
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Additional substitutions for cadmium plating may use similar technology
or alternative coatings. The choice of replacement plating will depend on
which properties of cadmium coating are most important. Although inferior in
terms of solderability and lubrication, zinc is already used whenever possible
because of reduced health and environmental concerns compared to cadmium (AESF
1989). Electroplated tin and gold are readily solderable, although gold is
very expensive. Tin is not effective in corrosion resistance, but the
development of tin-zinc alloys and a zinc-nickel alloy as possible substitutes
for cadmium is progressing (AESF 1989, Kirk-Othmer 1978). Chrome plating also
is an economical process to improve corrosion resistance of steel where
appearance is not important. Chrome offers the advantage of a low friction
surface and good wearability, but does not offer the same corrosion resistance
as cadmium (Iron Age 1980, AESF 1989).
Collapsible Tubes
Collapsible tubes are used to dispense a number of products ranging from
medicines to epoxy resin adhesives. While these tubes can be manufactured
from a variety of materials, lead tubes are used to dispense corrosive
products (lead is difficult to corrode) or to satisfy customer packaging
preferences. Lead tubes represent a very small fraction (less than one
percent) of the tube market. Of the lead tubes currently manufactured, most
are used for artists colors and the remainder for corrosive glues.
One of the possible substitutes for lead tubes is aluminum tubes with
phenolic epoxy lining. This aluminum technology does not differ in cost and
offers similar performance to the lead tubes. Another potential substitute
technology, laminate tubes manufactured with alternating layers of plastic and
aluminum, also can replace lead tubes and have similar costs (see Table SR-9).
- xxviii -
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Other Products
There are a variety of other products that contain lead and/or cadmium
that are disposed of in MSW facilities. These products, however, account for
a very small percent of the total amount disposed. The Other Products
category includes foil wine wrappers, used oil, rubber (elastomers), and
electric blankets/heating pads. Potential substitutes for these lead and
cadmium use areas are presented in Table SR-9.
- xxix
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Table Sft-9. Potential Substitutes for Miscellaneous Products Containing Lead or Cadmium
Lead or Cadmium Use
Potential Substitute
Performance Contents
Collapsible Tubes
Aluminum lined with phenolic epoxy
Plastic and aluminum laminates
Similar in performance to lead tubes.
Similar in performance to lead tubes.
foil Vine Wrappers
Plastic
Aluminum foil
Similar cost and performance to lead.
Similar cost and performance to lead.
Used OiI
Zinc organo-phosphates
Iron and zinc chlorides
Iron sulfides
Similar cost and performance to lead-
cadmium-based products.
Rubber (elastomer) Products
Pigments*
Vulcanizing agents
Dithiocarbamates (bismuth, copper, selenium,
tellurium, zinc, piperidium, thiazoles)
Cost and performance of potential substitute
varies depending on formulation.
Printing Inks
Dialyrid yellow
Dialyrid orange
More expensive than lead chromate and lead
sulfochromate. Less lightfast and opaque
than lead chromate and lead sulfochromate.
More expensive than lead chromate and lead
sulfochromate. Less lightfast and opaque
than lead chromate and lead sulfochromate.
Electric Blankets and Heating Pads
Undetermined1*
Undetermined
* For a discussion of potential substitutes for pigments in rubber, see previous discussion of pigments in the Plastics section.
b Although the use of cadmium-containing wires for electric blankets and heating pads has not been characterized and potential substitutes have not
been evaluated, it is likely that other copper alloy wires will be able to fully supplant cadmium-containing wires for this use.
Sources: ANPA 1989; BASF 1989a; EPA 1989; Kirk-Othmer 1983; NAPIN 1989; Teledyne 1989; Wine Institute 1989.
- xxx -
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REFERENCES
ADL. 1990. (November 15). Lead Use and Substitutes. Report to Lead
Industries Association. Prepared by Arthur D. Little, Inc., Cambridge, MA.
AESF. 1989 (July 31). American Electroplaters and Surface Finishers Society.
W. Safranek. Orlando, FL. Transcribed telephone conversation with Louis
Gardner, ICF Incorporated, Fairfax, VA.
ANPA. 1989a (August 14). American Newspaper Publishers Association. G.
Cashau, Director of Technical Research. Reston, VA. Transcribed telephone
conversation with Thomas Hok, ICF Incorporated, Fairfax, VA.
Arconium. 1989 (July 24). J. Hamilton, Sales Representative. Providence,
RI. Transcribed telephone conversation with Thomas Hok, ICF Incorporated
Fairfax, VA.
Argus. 1989a (May 10). M. Croce. New York, NY. Transcribed telephone
conversation with Mark Wagner, ICF Incorporated, Fairfax, VA.
Argus. 1989b (May 11). D. Stimpfl. New York, NY. Transcribed telephone
conversation with Mark Wagner, ICF Incorporated, Fairfax, VA.
Argus. 1989c (May 17). D. Brilliant. New York, NY. Transcribed telephone
conversation with Mark Wagner, ICF Incorporated, Fairfax, VA.
BASF. 1989a (May 16). Basic Organics Group. Transcribed telephone
conversation with Tanya Yudleman, ICF Incorporated, Fairfax, VA.
BASF. 1989b (August 14). R. Wagner, Manager in Charge of Product Compliance,
BASF, Clifton, NJ. Transcribed telephone conversation with Thomas Hok, ICF
Incorporated, Fairfax, VA.
Bayer-Mobay Corporation. 1989 (May 16). Transcribed telephone conversation
with Tanya Yudleman, ICF Incorporated, Fairfax, VA.
Bedford Chemical. D. Gauw. 1989 (May 4). Bedford Chemical, Division of
Ferro Corporation. Bedford, OH. Transcribed telephone conversation with Mark
Wagner, ICF Incorporated, Fairfax, VA.
Blanche, S.T. 1989. "Chrome-Tin Pink Glazes," Ceramic Engineering Scientific
Proceedings. Vol. 10, pp. 65-68.
Cadmium Council. 1989 (July 27). H. Murrow. New York, NY. Transcribed
telephone conversation with Louis Gardner, ICF Incorporated Fairfax, VA.
Chemical Business. 1989 (July/August). "The Assault on Batteries," p. 35-36.
CMI. 1989a (June 1). Can Manufacturers Institute. D. Karmol. Counsel.
Washington, DC. Transcribed telephone conversation with Thomas Hok, ICF
Incorporated, Fairfax, VA.
- xxxi -
-------
CMI. 1989b (July 28). Can Manufacturers Institute. D. Kannol. Counsel.
Washington, DC. Transcribed telephone conversation with Thomas R. Hok, ICF
Incorporated, Fairfax, VA.
Copper Development Association. 1989 (July 21). A Cohen. Greenwich, CT.
Transcribed telephone conversation with Louis Gardner, ICF Incorporated,
Fairfax, VA.
Corning Glass. 1989a (July 21). T. Seward. Transcribed telephone
conversation with Peter Weisberg, ICF Incorporated, Fairfax, -VA.
Corning Optics. R. Thompson. 1989b (July 21). Transcribed telephone
conversation with Peter Weisberg, ICF Incorporated, Fairfax, VA.
Corning Glass. D. Lopata. 1989c (May 30). Transcribed telephone
conversation with Peter Weisberg, ICF Incorporated, Fairfax, VA.
Corning Glass. J. Connelly. 1989d (July 26). Transcribed telephone
conversation with Peter Weisberg, ICF Incorporated, Fairfax, VA.
Degussa Corporation. D. Gillier. 1989 (August 14). Transcribed telephone
conversation with Louis Gardner, ICF Incorporated, Fairfax, VA.
EPA. 1989 (January). U.S. Environmental Protection Agency. Characterization
of Products Containing Lead and Cadmium in Municipal Solid Waste Facilities,
1970 to 2000. Prepared by Franklin Associates, Ltd. Prairie Village, KS.
EPA. 1990 (November). U.S. Environmental Protection Agency. Summary of
Pollution Prevention Act of 1990. Prepared by the Office of Pollution
Prevention, U.S. EPA. Washington, D.C.
Franklin Associates. 1990 (August). Characterization of Lead in Plastic
Products in Municipal Solid Waste, 1970 to 2000. Prairie Village, KS.
Indium Corporation of America. 1989a (July 19). R. Altieri. Applications
and Engineering, Utica, NY. Transcribed telephone conversation with Thomas
Hok, ICF Incorporated, Fairfax, VA.
Indium Corporation of America. 1989b (July 28). R. Altieri. Applications
and Engineering, Utica, NY. Transcribed telephone conversation with Thomas
Hok, ICF Incorporated, Fairfax, VA.
Indium Corporation of America. 1989c (August 15). J. Ferriter.
Applications and Engineering. Utica, NY. Transcribed telephone conversation
with Thomas Hok, ICF Incorporated, Fairfax, VA.
IPC. 1989a (July 20). Institute of Printed Circuits. D. Bergman. Chicago,
IL. Transcribed telephone conversation with Thomas R. Hok, ICF Incorporated,
Fairfax, VA.
IPC. 1989b (July 28). Institute of Printed Circuits. D. Bergman. Chicago,
IL. Transcribed telephone conversation with Thomas R. Hok, ICF Incorporated,
Fairfax, VA.
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Iron Age. 1980 (January 14). Cadmium's Plight Opens Field to Alternative
Coatings, p. 50.
Kapp Alloy and Wire, Inc. 1989 (July 19). D. Porter, Technical Director,
Altoona, PA. Transcribed telephone conversation with Thomas Hok, ICF
Incorporated, Fairfax, VA.
Keeler, R. 1987 (July). "Specialty Solders Outshine Tin/Lead in Problem
Areas." Electronic Packaging and Production, pp. 45-47.
Kirk-Othmer. 1978. Encyclopedia of Chemical Technology. John Wiley and Sons
Publishing Co., Inc. Volume 3, pp. 674-77; Vol. 3, pp. 569-639; Volume 6, p.
166; Volume 7, p. 45; Volume 8, pp. 827-869; Volume 15, pp. 241-274.
Kirk-Othmer. 1983. Encyclopedia of Chemical Technology. John Wiley and Sons
Publishing Co. Vol. 6, Vol. 14, pp. 168-183, 493-496; Vol. 18, pp. 184-206;
Vol. 20, p. 338.
Manko, H.H. 1979. Solders and Soldering. Published by McGraw-Hill Book
Company, New York, NY. Second edition.
Moli Energy. 1989 (January). Product literature on Molicel Lithium
batteries.
NAPIM. 1989 (August 14). National Association of Printing Ink Manufacturers.
P. Volpe, Technical Coordinator. Westchester, NY. Transcribed telephone
conversation with Thomas Hok, ICF Incorporated, Fairfax, VA.
NFPA. 1989 (July 31). National Food Processors Association. E. Elkins.
Washington, DC. Transcribed telephone conversation with Thomas Hok, ICF
Incorporated, Fairfax, VA.
Nielsen, WD. Undated. Metallurgy of Copper Base Alloys. Casting Engineering
& Foundry World. Reprint.
Palmer, J.G. 1988 (September). Executive Vice President, Pacific-Dunlop-GNB,
Incorporated, St. Paul, MN. "A Cleaner Environment: Removing the Barriers to
Lead-Acid Battery Recycling." Written in collaboration with M.L. Sappington,
P.E., President, Lake Engineering, Incorporated, Atlanta, GA.
Panasonic. Undated. "Batteries," a publication of Panasonic, Secaucus, NJ.
Piezo Kinetics Inc. 1989 (May 30 and July 27). R. Turner. Transcribed
telephone conversation with Peter Weisberg, ICF Incorporated, Fairfax, VA.
Plastic Additives Handbook. 1987. Hanser Publishers. Munich, Germany.
SAFT America. 1989a (July 14). G. Lupul. Maryland. Transcribed telephone
conversation with Donald Yee, ICF Incorporated, Fairfax, VA.
SAFT America. 1989b (July 14). G. Lupul. Maryland. Transcribed telephone
conversation with Donald Yee, ICF Incorporated, Fairfax, VA.
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SAFT America. 1989c (August 15). P. Scardaville, Director of Engineering.
Valdosta, GA. Transcribed telephone conversation with Alex Greenwood, ICF
Incorporated, Fairfax, VA.
Sylvania and Laxman Ltd. 1989a (June 1). R. Marlor. Transcribed telephone
conversation with Peter Weisberg, ICF Incorporated, Fairfax, VA.
Sylvania and Laxman, Limited. 1989b (July 18). R. Marlor. Manager, Glass
and Ceramics. Salem, MA. Transcribed telephone conversation with Thomas
Hok, ICF Incorporated, Fairfax, VA.
Sylvania and Laxman, Limited. 1989c (July 28). R. Marlor, Manager, Glass and
Ceramics, Salem, MA. Transcribed telephone conversation with Thomas R. Hok,
ICF Incorporated, Fairfax, VA.
Talco Metals. 1989 (July 18). C. Carabello, Sales Representative.
Philadelphia, PA. Transcribed telephone conversation with Thomas R. Hok, ICF
Incorporated, Fairfax, VA.
Teledyne Packaging. 1989 (May 31). K. Barry. New Jersey. Transcribed
telephone conversation with Thomas Hok, ICF Incorporated, Fairfax, VA.
Wine Institute. 1989 (June 1). W. Lee. San Francisco, CA. Transcribed
telephone conversation with Peter Weisberg, ICF Incorporated, Fairfax, VA.
Yardney Battery. 1989a (July 13). T. Aretakis. Connecticut. Transcribed
telephone conversation with Donald Yee, ICF Incorporated, Fairfax, VA.
Yardney Battery. 1989b (July 20). D. Wissocker. Massachusetts. Transcribed
telephone conversation with Donald Yee, ICF Incorporated, Fairfax, VA.
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I. INTRODUCTION
The use of lead- and cadmium-containing articles that ultimately are
disposed of in municipal solid waste (MSW) facilities is the focus of a joint
project by the Office of Toxic Substances and the Office of Solid Waste of the
U.S. Environmental Protection Agency. The use and substitutes analysis
provided in this report characterizes and discusses technologically feasible
substitutes for lead and cadmium in products identified in an earlier EPA
report entitled "Characterization of Products Containing Lead and Cadmium in
Municipal Solid Waste, 1970 to 2000." The products discussed in this report
are as follows:
plastics;
pigments;
solder;
nickel-cadmium batteries;
glass and ceramic products;
brass and bronze products;
cadmium plated products;
collapsible tubes;
lead-acid batteries; and
other products.
Table 1 identifies the amount of lead and cadmium in each of these product
areas discarded in MSW in 1986. As the table indicates, the majority of
discards is in the battery, plastics, pigments, solder, and glass categories.
These uses account for 99 percent of the lead" and 89 percent of the
cadmium disposed of in MSW.
* Other products containing lead and/or cadmium include rubber products,
printing inks, used oil, foil wine wrappers, and electric blankets and heating
pads.
** Lead acid batteries accounted for 138,043 tons of lead discards in
1986, about 2/3 of the total lead discards in MSW (EPA 1989). This use of
lead is not a major focus of this report, however, because lead-acid batteries
have been characterized in other reports prepared for and by EPA (e.g., Palmer
1988) and because substitutes for this battery system are not currently
available.
- 1 -
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Table 1. Discards of Lead and Cadmium by Use Area in MSW in 1986
Product Area
Lead Acid Batteries
Plastics
Pigments3
Solder
Nickel/Cadmium Batteries
Glass and Ceramic Products
Brass and Bronze Products
Plated Products
Collapsible Tubes
Rubber Products
Other Products6
Lead Discards
(tons)
138,043
3,174
1,131
8,369
0
60,714
321
0
639
70
671
Cadmium Discards
(tons)
0
564
70
0
927
29
0
185
0
6
1
a Discards of pigments do not include pigments consumed in plastics,
glass/ceramic products, or rubber products. These discards are
covered in the sections on plastics, glass/ceramic products, and
rubber products.
b Other products include used oil, foil wine wrappers, electric
blankets and heating pads, and television and radio chassis. 279
tons of lead were discarded as part of television and radio chassis,
but future discards are expected to be zero.
Source: EPA 1989, Franklin 1990.
- 2 -
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Lead and cadmium have been used in the products identified in this
report as additives, components, and coatings to improve performance, fulfill
certain customer preferences, and to impart certain characteristics to end
products based on the physical/chemical properties of the metals and/or
compounds made from them. The use of lead- and cadmium-containing products is
characterized for each product area with emphasis on the critical properties
that they provide to finished products.
Potential and existing substitutes that can replace lead and cadmium in
these uses are characterized to the extent that information is available from
secondary data sources. Technical feasibility is the only basis used in th-is
analysis to identify substitutes. Thus, only in cases where no alternative is
currently available that imparts the same properties provided by lead or
cadmium does this report fail to present potential substitutes. Information
on potential substitutes was identified from published sources (standard texts
and journal articles) and conversations with industry contacts.
Some qualitative cost information is presented for potential substitutes,
but estimates of the likely market shares that potential substitutes would
absorb in the event that lead and cadmium products were no longer available
have not been developed in this study. However, the information presented
here along with other background data developed during the project provides a
solid foundation for estimating market shares and other more detailed economic
information for potential substitutes.
A. Limitations
This report should be considered as a preliminary analysis due to the
limitations of its scope. EPA has not performed primary research to identify
the substitutes for lead and cadmium described in this report. Only
substances identified in published sources or by industry contacts and that
- 3 -
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were known or considered to be possible substitutes have been included in this
analysis. Because this report characterizes substitutes for both lead and
cadmium products, lead and cadmium products are not considered as substitutes
for each other although these products sometimes may be technically feasible
options. Furthermore, the substitution in this report is based only on
technical feasibility and does not quantitatively assess economic factors that
affect substitution or the effect of potential substitutes on end products
(e.g., different service lives for substitute products). This report,
therefore, is not intended to draw conclusions about the viability of actual
substitution. No economic analysis has been performed to estimate the impacts
of substituting for lead and/or cadmium products.
In addition, toxicities of substitutes are not discussed in this report
and toxicity was not a criteria for identifying potential substitutes. Many of
the classes of chemicals assessed have intrinsic toxicities that would be of
great concern in other parts of the manufacturing processes where there wouid
be human or environmental exposure to more bio-available forms of the chemical
or chemicals. A more focused, in-depth substitute characterization for each
chemical substitute in each use area would be required to adequately assess
the hazard presented by potential substitutes.
B. References
EPA. 1989 (January). U.S. Environmental Protection Agency. Characterization
of Products Containing Lead and Cadmium in Municipal Solid Waste Facilities,
1970 to 2000. Prepared by Franklin Associates Ltd., Prairie Village, KS.
Franklin Associates. 1990 (August). Characterization of Lead in Plastic
Products in Municipal Solid Waste, 1970 to 2000. Prairie Village, KS.
Palmer, J.G. 1988 (September). Executive Vice President, Pacific-Dunlop-GNB,
Incorporated, St. Paul, MN. "A Cleaner Environment: Removing the Barriers to
Lead-Acid Battery Recycling." Written in collaboration with M.L. Sappington,
P.E., President, Lake Engineering, Incorporated, Atlanta, GA.
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II. PLASTICS -
A. Overview of the Plastics Industry
Plastics can be categorized into two major groups, thermoplastic and
thermoset, based on how the plastic reacts when heated. Thermoplastic resins
can be melted and solidified in a reversible process, while thermosetting
resins initially liquify with heat, but then permanently solidify with further
heating. Because of the advantages associated with using thermoplastic resins
(i.e., that they can be reworked or reformed and are therefore easier to
handle), over 90 percent of all resins produced are thermoplastic (Kirk-Othmer
1983). Table 2 identifies some of the most common thermoplastic resins.
Thermosetting resins are exemplified by certain types of polyesters and
polyurethanes, as well as phenol-formaldehyde, urea-formaldehyde, and
melamine-formaldehyde resins. Thermoset resins are characterized by
irreversible bond formation (cross-linking) between polymer chains that occurs
during the heat curing stages of processing. Table 2 identifies the major
categories of thermosetting resins.
Processing of resins takes place through a number of different
techniques including extrusion, molding, thermo- or vacuum-forming, casting,
and calendaring. Approximately half of all resins are converted into products
by extrusion. The extrusion process is continuous, making products of uniform
cross-section and infinite length that can be rolled or coiled, cut into
lengths, or otherwise packaged. Typical products that are made by extrusion
include film, sheet, pipe, tubing, profiles,* coated wire, and coated paper
(Kirk-Othmer 1983).
* Profiles are typified by such products as channels, gaskets, decorative
trim, siding panels, window frames, and other rigid structures used in indoor
and outdoor construction and building.
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Table 2. Representative Thermoplastic and Thermosetting Resins
Amorphous* Thermoplastic Resins
Acrylonitrile-butadiene-styrene (ABS)
Cellulose acetate
Polycarbonates
Polyacrylates and methacrylates
Polystyrene
Polyvinyl chloride (PVC)
Styrene-acrylonitrile (SAN)
Crystallineb Thermoplastic Resins
Polyethylene, low density (LDPE)
Polyethylene, high density (HDPE)
Polypropylene
Polyacetals
Nylons
Polyesters0
Fluoropolymers
Thermosetting Resins
Phenol- formaldehyde
Urea-formaldehyde
Melamineformaldehyde
Polyesters
Polyurethanes
' Amorphous thermoplastics are character-
ized by no distinct melting and freezing
points.
b Crystalline thermoplastics have well
defined melting and freezing points.
c Some polyesters are thermoplastics,
while others (e.g., phenol-formaldehyde
resins) are thermosetting.
Source: Kirk-Othmer 1983.
- 6 -
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Molding is a process by which molten thermoplastic resins are injected
under pressure into a mold and cooled until the article can be removed from
the mold without distortion. Thermoforming of amorphous resins, e.g.,
polystyrene, polyvinyl chloride (PVC), and polymethyl methacrylate, is also
common, as is casting of acrylates between two glass sheets. Calendaring
operations consist of making sheets from PVC and acrylonitrile butadiene -
styrene (ABS) resins that are used in the manufacture of luggage, wall
paneling, and furniture. Thermosetting resins are processed almost
exclusively by molding operations, although some flexible polyurethane foams
are processed in the form of a slab (Kirk-Othmer 1983).
B. Additives Used in the Processing of Plastics
A wide range of plastic processing chemicals (additives) are available
to serve various functions in some or all of the resin types identified in
Table 2. Additives can impart a particular characteristic to the end product
or may be required to preserve the integrity of the plastic resin during
processing or use. The range of all chemical additives (lead and cadmium as
well as non-lead/cadmium additives) are grouped into the following categories
(Radian 1987) :
Antioxidants;
Antistatic agents;
Blowing agents;
Catalysts and cure agents;
Colorants;
Coupling agents;
Fillers and reinforcers; <
Flame retardants;
Free radical initiators;
Heat stabilizers;
Lubricants and mold release agents;
Plasticizers;
Preservatives;
Solution modifiers; and
UV stabilizers.
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Fillers and reinforcers, plasticizers, and flame retardants make up the
vast majority of additives consumption in the plastics industry, accounting
for almost 92 percent of consumption by weight (Modern Plastics 1982).
Colorants and heat stabilizers, major compounds formulated with lead and/or
cadmium, account for 3.9 and 1.0 percent by weight of all plastic additives
consumption, respectively.
1. Additives Containing Lead and/or Cadmium
Additives that contain lead and cadmium do not account for a large
proportion of total additive consumption, but due to the large volume of
plastic produced annually, approximately 57 billion pounds in 1988, a
substantial amount of these products is consumed (Modern Plastic 1988).
Section C of this chapter provides an in-depth discussion of actual
consumption of these lead- and cadmium-containing products.
In addition to heat stabilizers and colorants, there is a small amount
of lead and cadmium present in certain polymerization catalysts and
lubricants. Lubricants based on metallic soaps, including lead and cadmium
stearates as well as the more common calcium, aluminum, magnesium, and zinc
stearates, are used with many types of resins (including PVC resins) where
they also act as heat stabilizers. Lead and cadmium may also be present in
certain metal oxide and other catalysts, either incorporated intentionally or
present as impurities in other metal-based catalysts (Radian 1987). These
lubricant and catalyst uses of lead- and cadmium-based products account for a
small amount of the lead- and cadmium-based plastic additives and hence, are
not discussed in the remainder of this report.
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a. Lead- and Cadmium-containing Pigments Used with Plastic
Resins
Colorants used in plastic resins number into the hundreds.
Combined with the wide variety of polymers, the permutations that exist in
coloring plastics are enormous. In many cases, "color houses" exist to match
a given polymer with a compatible colorant. While hue and shade requirements
eliminate a fair share of the possible combinations of colorants and plastics,
solubility of the colorant in the medium is also important in the selection
process. Solubility determines whether a dye or a pigment is used. If the
colorant must be soluble, a dye is normally chosen; if solubility is not a
factor, pigments are usually used because they are less expensive (Plastics
Engineering Handbook 1987).
Dyes are soluble in plastics and present minimal problems when mixed
with a polymer. Pigments, on the other hand, are supplied in the form of a
finely ground powder and must be dispersed or distributed evenly in the
polymer. Dispersion of a pigment is a physical process consisting of a number
of separate steps. First, the dry powder must be broken down into the desired
particle size; second, the powder is blended with a resin or binder so that
the pigment is "wetted" and a homogenous mix is produced; and finally, to
counteract the cohesive forces that normally try to reagglomerate the
particles, the dispersion must be stabilized. Dispersability is also
important since it is one of the few ways to broadly classify pigments into
either inorganic or organic* (Plastic Additives Handbook 1987). Generally,
* Organic pigments, by definition, are compounds containing carbon and
although some organic molecules may contain metal or metal salts, the
inorganic component is considered secondary (responsible more for undertones
than primary hue color) (Brannon 1988). In addition, not only lead and
cadmium ions, but other metal ions could impart the desired properties to
these organic pigments. Lead and cadmium based organic pigments, therefore,
are not considered significant products and are not discussed in this report.
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inorganic pigments have a fairly uniform particle size and are easier to
disperse than organic pigments, which tend to have non-uniform particle size
(Plastics Engineering Handbook 1987).
Other performance properties that must be considered in the selection of
a colorant include heat stability, lightfastness, opacity, and chemical
resistance. Lead and cadmium pigments have most of the same characteristics
as other inorganic pigments for these properties and so this discussion
focuses primarily on the properties for inorganic pigments in general. Where
possible, indications are also given as to the specific performance properties
of lead and cadmium pigments.
During the manufacturing or processing of colored plastics, heat can be
the cause of coloristic change. Heat or thermal stability is not only
dependent on the processing temperature, but also the duration of exposure and
the acceptable shade tolerance (Plastic Additive Handbook 1987). In general,
inorganic pigments possess greater heat stability than organic pigments, which
degrade or sublime when exposed to high temperatures for extended periods of
time (Brannon 1988).
Lightfastness of plastics is another important characteristic of
pigments and is defined as the probability that a plastic will lose its color
intensity due to light, especially sunlight. This property is not solely
dependent on the pigment, but is dependent on the polymer system as well.
Lightfastness of a colorant is analyzed, therefore, in terms of the full
colorant/plastic system (Plastic Additives Handbook 1987). In addition, color
loss due to exposure to solvents, acids, or alkalies is not just a chemical
property of the pigment, but is attributable to the polymer system (Brannon
1988). In general, neutral organic pigments exhibit good chemical resistance,
. 10 -
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whereas varying degrees of chemical sensitivity exist for inorganics and
organic metal salts.
Opacity and hiding power also may be important characteristics for
pigments. These terms usually are used to describe the ability of a pigment
to scatter light and hide the resin matrix (Brannon 1988). Whether a pigment
is described as being opaque, semi-opaque, or transparent depends on the
pigment's refractive index. Differences in the refractive indices between
pigments and polymer systems may result in a greater scattering of light,
which gives greater hiding power or opacity. In general, the larger pigments
(inorganics), exhibit hiding power, but smaller pigments (organics), have
greater transparency (Brannon 1988). Table 3 provides some of the performance
characteristics for lead and cadmium-based pigments.
i. Lead-containing Pigments
Lead-based pigments used in plastics include chromates
and molybdate oranges. The plastics industry has been cited as one of the
largest consumer uses of lead chromate pigments* (EPA 1989). Currently, the
use of lead-based pigments is declining because of health-related concerns
(EPA 1989). Most users of these pigments have cited the relatively low cost
(about $2/pound in 1985 for molybdate orange) as a reason for their continued
use (Modern Plastics 1985). The hue associated with lead-based pigments range
from greenish or light yellows to deep oranges and primrose for lead chromates
and from reddish yellows to red-shade oranges for molybdate orange. Lead
pigments are inexpensive, provide good tint strength and have a high degree of
hiding power (opacity). Lead chromates darken upon exposure to light, heat,
* Other uses of lead chromate pigments include interior and exterior
paints, automotive finishes, textiles, and paper products (EPA 1989).
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Table 3. Lead and Cadmium Inorganic Pigments and Their Performance Properties
Pigment
Lead:
Chromate
Sulfate
Molybdate
Chroeute + Icon Blue
Cadmium:
Sulfid.
Sulfide + Zinc
Sulfide + Selenium
Sulfide » Mercury
Heat Stability*
Hues Chemical Formula (*C)
Orange
Yellow-orange
Reddish orange
Greenish yellow to
Medium shades of olive green
Orange shade of yellow
Greenish yellow
Red and maroon
Reddish orange to bluish red
Pb
PbCr04 230-250
PbS04 230-250
PbMoO4 220-250
--
Cd
CdS 300
Cd + Zn
CdS + Se 300
CdS + Hg
Remarks on Performance0
Opacity/ (Compatible Polymer/
Lightfastness6 Chemical Resistance Hiding Power Resin)
Opaque
6-8 Sensitive to acids/bases PVC, LDPE + HOPE, PS -
6"8 Sensitive to acids/bases PVC, LDPE + HOPE, PS -
6-8 Sensitive to acids/bases PVC, LDPE + HOPE. PS -
-
Opaque
8 Sensitive to acids General suitability
8 Sensitive to acids General suitability
For heat stability, the temperature is stated at which no coloristic changes occurred during normal dwell times (approximately 5 minutes) in processing machines.
b Determination of lightfastness is carried out in accordance with DIN 53 389. 1 is the lowest value; * has 8 times the fastness level of 1; the highest value is 8
testing not normally being carried out beyond this level. See Plastic Additives Handbook (1987) for more information.
PS - polystyrene; LDPE - low density polyethylene; PMMA - polymethyl methacrylate; HOPE = high density polyethylene; PVC - polyvinyl chloride
H-PVC m Unplasticized PVC. '
c Polymer Codes:
Polymer Performance: + denotes suitable/recommended; - limited suitability/recommended; - denotes not suitable/recommended; () denotes a qualification of the statement
* denotes caution is needed in the case of HOPE articles sensitive to distortion.
Source: Plastic Additives Handbook 1987, Brannon 1988.
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(excess of 400*F) and in the presence of sulfides. They also demonstrate
sensitivity to acids and bases (Brannon 1988).
ii. Cadmium-containing Pigments
Cadmium-based pigments are actually classified as
sulfides, sulfoselenide or mercury complexes. Pure cadmium sulfide is an
orange shade of yellow, but when zinc sulfide is added, the shade shifts to
greenish yellow. On the other hand, cadmium sulfoselenide is found when
selenium is added to the cadmium sulfide compound producing a red to maroon
shade. Finally, mercadmiums are produced when mercury combines with the
cadmium sulfide compound yielding a reddish orange to bluish red hue. Cadmium
pigments are expensive (about $15.00/lb. for cadmium sulfide) and the cost
continues to increase (BASF 1989). For example, the price of cadmium pigments
rose 50 percent from September 1987 to September 1988 due to a 900 percent
increase in the cost of cadmium metals from December 1986 to September 1988
(Modern Plastics 1988). Cadmium pigments exhibit brilliant shades of color,
have a high heat stability (cadmiums are considered irreplaceable in high
temperature nylon and polyester applications), have good lightfastness, and
are sensitive to acids (Brannon 1988).
b. Lead- and Cadmium-based Heat Stabilizers Used in PVC and
Other Resins
Heat stabilizers are used to prevent the degradation of
resins during processing, when molten plastic resins are exposed to high
temperatures, or are used to extend the life of the final products into which
they are incorporated. Polyvinyl chloride is especially vulnerable to
decomposition and degradation during processing; consequently this resin
accounts for the major share of consumption of heat stabilizers. In addition,
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chlorinated polyethylene and blends of ABS and PVC often require stabilization
(Plastics Engineering Handbook 1987).
Polyvinyl chloride stabilizers prevent changes in color and performance
during processing and use, and are usually based on lead, organotin or
cadmium/barium systems. The specific choice of heat stabilizer is determined
by the specific effect on end-products that is required. Many formulations
are available in two forms: liquid and solid. Liquids (there are no liquid
lead-based stabilizers) are usually used with flexible polyvinyl chloride, and
solids, with higher metal concentrations, are used in rigid polyvinyl chloride
because it is processed at higher temperatures. Table 4 presents some
representative lead- and cadmium-based products that are used in polyvinyl
chloride resins (Plastic Additives Handbook 1987).
i. Lead-containing Heat Stabilizers
Lead compounds are the oldest group of stabilizers.
Among their advantages is the ability to form complexes with chlorine,
preventing the formation of free radicals that destabilize PVC. The lead
chloride complexes that form do not have any destabilizing effect on PVC and
thus co-stabilizers such as polyols and phosphites are not required (Plastic
Engineering Handbook 1987).
One lead stabilizer, lead stearate, has the added characteristic of
being an excellent lubricant, providing it with a second function during PVC
processing. Lead stearate, therefore, is added to the basic lead salts to
create an excellent mixture that is compatible with all PVC types.
Because neither lead stabilizers nor their reaction products with
chlorine increase the conductivity of PVC, they are used predominantly in wire
and cable insulation applications. Lead stabilizers are the best products
available in this area, providing good electrical properties (e.g.,
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Table 4. Representative Cadmium and Lead-based Heat Stabilizers and Their Properties
Stabilizer
Concentration of
Stabiliser in FVC
(phr)
Typical Uses
Properties and Reasons for Use
Lead Stabilizers
Tribaslc lead sulfate 2.0-4.0
Dibasic lead phosphite 2.0-4.0
Dibasic lead phthallate 0.5-i.O
Dibasic lead stearate 0.5-1.0
Normal lead stearate 0.5-1.0
Dibasic lead carbonate 0.5-1.5
e Hire and cable insulation material
e Pressure pipes and fittings
e Interior and exterior sheets and profiles
Do not require co-stabilizers or other
additives to increase performance
Do not increase the conductivity of FVC
articles
Good processability
Impart good mechanical properties to end
products
Cadmium Stabilizers*
Liquids
Ba/Cd decanoate (and
other fatty acid salts)
Ba/Cd alkyl phenols
Ba/Cd benzoates
Solids
Ba/Cd decanoate
Ba/Cd alkyl phenols
Ba/Cd benzoates
1.5-2.0
1.5-2.0
1.5-2.0
1.5-2.5
1.5-2.5
1.5-2.5
White outdoor profiles
Furniture film
Floor tiles
Shoes and soles
Hoses
e High performance applications
Light co-stabilizing effect
Good transparency
Used in a wide range of products
Ease of handling
Excellent heat stability and self-
lubricating
e Same as for liquid cadmium stabilizers
OTE: phr - parta per hundred parts of resin.
Cadmium containing stabilizers are numerous and the properties that each impacts to finished products can vary significantly.
Sources: Plastic Additives Handbook 1987, Plastics Engineering Handbook 1987.
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insulation) and the heat stability required during service (Bedford 1989,
Plastics Additives Handbook 1987).
Lead-based stabilizers, although effective in many other applications,
have been and continue to be eliminated from most applications. Their use in
pressure pipes, sewage pipes, gas pipes, gutters, profiles and other
applications continues to decline because of toxicity concerns and because
economically and technically feasible substitutes are available for these
applications (Argus 1989a). For these reasons, lead-containing PVC
stabilizers currently consumed are used almost exclusively in the electrical
cable insulation industry (Argus 1989b). Table 5 shows some of the advantages
and disadvantages of lead heat stabilizers and Table 6 presents current and
past applications. In 1983, expectations that the National Sanitation
Foundation would approve lead-based stabilizers for PVC in potable water pipe
promoted growth in lead stabilizers (Modern Plastics 1983), but approval was
not granted causing a move away from use in non-potable water pipe as well
(Bedford 1989).*
ii. Cadmium-containing Heat Stabilizers
The predominant cadmium heat stabilizers are actually
mixtures of barium and cadmium salts of natural straight chain fatty acids,
branched synthetic acids, and occasionally alkyl phenols and benzoic acid
derivatives. The combination of barium and cadmium salts provides a
synergistic effect, the cadmium salts providing good color stability in
If non-potable water pipe were continued to be manufactured with lead,
while potable water pipe was made with non-lead products, there would be
problems with cross contamination, dual inventories, and confusion during
installation. As economically feasible substitutes for lead heat stabilizers
in water and sewage pipes are available, lead use is expected to be completely
eliminated from these uses (Bedford 1989).
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Table 5. Advantages/Disadvantages of Lead-based Heat Stabilizers
Advantages
Disadvantages
Excellent electrical properties
Excellent lubrication
Good processability
Inexpensive
Wide range of forms: oiled
powders, flakes and pellets to
reduce dusting
Too alkaline for some
applications
Cannot be used with transparent
PVC articles
Certain pigments are incompatible
with lead salts
Dust formation and worker
exposure problems
Health and toxicity concerns
associated with end-products
Sources: Plastics Additive Handbook 1987, Bedford 1989, Kirk-Othmer 1983,
Radian 1987, Vinyl Institute 1989b.
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Table 6. Current and Declining Uses of Lead-based Heat Stabilizers
Current Uses
Declining Uses
Electrical cable insulation
Electrical conduit
Wire coating
Telephone cable insulation
Garden hose
Footwear
Water pipe
Sewage pipe
Gutters
Indoor and outdoor profiles
Sound records (LPs)
Floppy disk jackets
Traffic cones
Sources: Bedford 1989, Franklin 1990, Kirk-Othmer 1983, Radian 1987, Vinyl
Institute 1989b.
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initial processing and the barium salts providing good long-term thermal
stability during use (Chemical Additives Handbook 1987).
Cadmium stabilizers yield cadmium chloride, which unlike lead chloride,
has a destablizing effect on PVC, necessitating the addition of deactivating
components such as polyols, phenolic antioxidants, and phosphites. These co-
stabilizing agents further improve the performance of the barium/cadmium heat
stabilizers.
The complex composition of barium/cadmium stabilizers requires that
special attention be paid to other components of plastic additives systems
(e.g., antioxidants, plasticizers, and fillers) so as to ensure optimum
properties. Special attention is also necessary during processing (heating
and formulating) technique and when selecting characteristics of the end
product, thereby accounting for the wide variety of barium/cadmium
stabilizers.
Barium/cadmium (Ba/Cd) stabilizers can be separated into liquid and
solid formulations. Solids in the form of powders are metal salts of fatty
acids with phenolic antioxidants and polyols used in combination with liquid
phosphites and liquid epoxy plasticizers. Formulations containing 10 percent
cadmium or more are used extensively in rigid PVC applications such as
pigmented profiles and sheets for the building sector. Powders containing
less than 10 percent cadmium are used in flexible PVC for shoes, hoses, and
profiles. Powdered stabilizers are self-lubricating, but processing
conditions requiring a large amount of stabilizer may result in over
lubrication. This problem can be overcome by combining liquid and powdered
Ba/Cd stabilizers (Argus 1989b).
Liquid stabilizers are not self-lubricating, but are easier to handle
than solids because they are liquid and because they already have phosphites
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mixed in. Because of lower metal content they are sufficient only for lower
temperature processing (i.e., flexible PVC only). Often liquid Ba/Cd
stabilizers also contain zinc compounds that improve early color and sulfide
stain resistance (Vinyl Institute 1989b). Table 7 presents the advantages and
disadvantages of barium-cadmium heat stabilizers, and Table 8 presents use
areas for Ba/Cd stabilizers.
C. Consumption of Lead- and Cadmium-containing Products in Plastics
Most of the consumption of lead and cadmium in plastics can be broken
down into the four following areas: lead-based pigments, cadmium-based
pigments, lead-based heat stabilizers, and cadmium-based heat stabilizers.
Although lead and cadmium may be present in other plastic additives (e.g.,
lubricants, mold release agents, catalysts, or blowing agent "kickers") or amy
be impurities in certain metal-based additives, these minor sources of lead
and cadmium are not analyzed in this report. The remainder of this section
identifies consumption by major use area.
1- Consumption of Lead-based Pigments
Table 9 shows the amount of discarded lead-based pigments at
intervals for the period from 1970 until 1986. Although the discards of
plastic resins have more than tripled over that period, the discards of lead-
based pigments have increased much more slowly. This difference may be due to
increasing concern about possible health effects of lead in plastic products.
By calculating the amount of lead in pigments lost during plastics
manufacturing (assumed to be about 2 percent for this analysis), the amount of
lead that is found in plastic products can be estimated (EPA 1989). The resin
quantity used in calculating the lead/resin weight ratio includes resins
containing no lead pigments and therefore does not reflect a typical or
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Table 7. Advantages and Disadvantages of Cadmium-based
Heat Stabilizers
Stabilizer
Type
Advantages
Disadvantages
Powdered Ba/Cd
Very good heat
stability
Self-lubricating
Wide range of
products
High metal content
Excellent for
outdoor
applications when
combined with
liquid phosphites
and epoxy
plasticizers
Must be combined with
liquid phosphites and epoxy
plasticizers
Sensitivity to water
causing reversible
cloudiness in transparent
products
Dust problems
Liquid Ba/Cd
Easier to handle
Wide range of
products
Prevents
stabilizer plate-
out and dispersion
problems
Added light
stability because
of phosphites and
epoxy plasticizers
-- excellent for
outdoor
applications
Limited self-lubrication
Odor that may be maintained
in finished products
Water sensitivity
Sources: Plastics Additives Handbook 1987, Bedford 1989, Kirk-Othmer 1983,
Radian 1987.
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Table 8. Uses for Cadmium-based Heat Stabilizers
Stabilizer Type Uses
Powdered Ba/Cd Extruded pigmented rigid PVC profiles
Extruded rigid sheets
Liquid Ba/Cd Extruded flexible PVC profiles and articles
Injection molded sandals and shoe soles
Calendared films for furniture, decoration, or
agricultural uses
Sources: Plastics Additives Handbook 1987, Bedford 1989, Kirk-Othmer 1983,
Radian 1987.
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Table 9. Discards of Lead in Pigments for Plastic in MSW
Lead in Total Resin Discarded
Pigments Discarded* in Nonfood Applications1"
Year (tons) (thousands of tons) Lead/Resin Ratio
1970
1975
1980
1986
647
813
967
990
2,061
3,098
5,103
8,111
0.00031
0.00026
0.00019
0.00012
Note: The term resin refers to the type of plastic. The resins included in
this consumption table could include all of the resins identified in
Table 2.
* Adjusted for net exports and with manufacturing losses estimated to be 2
percent; although the source discusses cadmium pigments, lead-based pigments
are found in similar forms, and therefore similar losses are expected (Yost
and Greenkorn 1984).
b Total resin figure includes resins containing no lead-based pigments.
Sources: EPA 1989, Franklin 1990.
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average concentration of lead that may be found in lead containing plastic.
It serves, however, as a measure of the demand for lead-based pigments
relative to the demand for plastics. As can be seen in the lead/resin weight
ratio, the use of lead-based colorants has declined significantly.
2. Consumption of Cadmium-based Pigments
The trend for cadmium in pigments discarded is illustrated in
Table 10. Although used in applications slightly different from those for
lead-based pigments, cadmium-containing compounds often have been replaced by
organic colorants (or sometimes by other inorganic compounds) largely because
of health concerns. Another factor that may have contributed to this decline
has been that the tremendous increase in the price of cadmium as other
applications (e.g. nickel-cadmium batteries) has placed additional demands on
the available supply of cadmium (Bedford 1989).
Calculating the weight of cadmium found in pigments was not necessary;
the amount of cadmium used in colorant manufacture was available from the U.S.
Bureau of Mines. However, it was still necessary to estimate the amount of
cadmium lost during the manufacture of plastics. From the net quantity of
cadmium remaining, the cadmium/resin weight ratio was calculated. As can be
seen in Table 10, demand for cadmium pigments (relative to resin demand) has
decreased.
3. Consumption of Lead-based Heat Stabilizers
The change in demand for lead-based heat stabilizers (relative to
resin demand) has not been great over the 17 year period shown in Table 11
(1970 to 1986). The discards of PVC resin have increased by slightly more than
200 percent. Unlike consumption of lead-based pigments, however, the demand
for lead-based heat stabilizers has increased, albeit at a lower rate than the
demand for resin. Because heat stabilizers affect the working properties of
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Table 10. Discards of Cadmium in Pigments for Plastic in MSW
Cadmium in
Pigments Discarded*
Year (tons)
Total Resin Discarded
in Nonfood Applications1"
(thousands of tons)
Cadmium/Resin Ratio
1970
1975
1980
1986
162
256
259
259
2,061
3,098
5,013
8,111
0.000079
0.000083
0.000052
0.000032
Note: The term resin refers to the type of plastic. Practically, plastics
are classified by the nature of the major resin(s) used in their
manufacture. The resins included in this consumption table could
include all of the resins identified in Table 2.
* Adjusted for net exports and with manufacturing losses assumed to be 6
percent (Yost and Greenkorn 1984).
b Total resin figure includes resins containing no cadmium-based pigments.
Source: EPA 1989.
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Table 11. Discards of Lead in Stabilizers for PVC in MSW
Lead in
Stabilizers Discarded"
Year (tons)
1970 770
1975 1,284
1980 1,746
1986 2,184
Total Resin Discarded
in Nonfood Applications1"
(thousands of tons) Lead/Resin Ratio
275 0.0028
523 0.0025
624 0.0028
879 0.0025
Note: The term resin in this table refers only to polyvinyl chloride (PVC)
resins.
Based on 1 percent manufacturing losses (Yost and Greenkorn 1984) .
b Total resin figure includes PVC resin containing stabilizers other than lead
based stabilizers.
Source: EPA 1989, Franklin 1990.
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the resin, it is generally more difficult to find suitable replacements for
lead-based products in this application.
Lead-based heat stabilizers are used predominantly in PVC resins. After
accounting for lead lost during manufacturing, the amount of lead in PVC
products was estimated. From this figure, the lead/PVC weight ratio could be
calculated. Similar to the methodology used for pigments, the resin quantity
used to estimate the lead/resin ratio includes PVC not containing any lead.
4. Consumption of Cadmium-based Heat Stabilizers
Table 12 shows the trend in the discards of cadmium-containing
heat stabilizers for the period 1970-1986. From the net quantity of cadmium,
the cadmium/resin weight ratio was calculated. As can be seen in the table,
unlike the lead compounds, demand for cadmium heat-stabilizers (relative to
resin demand) has decreased dramatically. The difference in the patterns of
use (compared to lead) may be a result of the increase in cadmium's price and
resultant attention to reformulating with lower cadmium content (Argus 1989b,
Bedford 1989).*
D. Potential Substitutes for Lead- and Cadmium-containine Additives for
Plastics
The selection of a particular lead or cadmium pigment and/or heat
stabilizer is dependent on processing requirements, resin characteristics, and
end-product uses. Identification of potential substitutes is, therefore, a
complicated and application-specific task. There are, however, some general
classes of substitutes available for each cadmium and lead-based additive
type. The following sections describe the performance, cost, feasibility, and
* Another source at Argus (unknown) considers the 1970 data presented in
Table 10 to be suspect. He characterizes lead and cadmium consumption to be
essentially constant for more than ten years (Vinyl Institute 1989b).
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Table 12. Discards of Cadmium in Stabilizers for PVC in MSW
Cadmium in
Stabilizers Discarded"
Year (tons)
1970 241
1975 280
1980 273
1986 305
Total Resin Discarded
in Nonfood Applications1*
(thousands of tons) Cadmium/Resin Ratio
275 0.00088
523 0.00054
624 0.00044
879 0.00035
Note: The term resin in this table refers only to polyvinylchloride
(PVC) resins.
Manufacturing losses are assumed to be 2 percent (Yost and Greenkorn 1984).
b Total resin includes PVC resins containing stabilizers without cadmium.
Source: EPA 1989.
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other considerations that dictate how potential substitutes can replace
traditional lead and cadmium products.
1. Potential Substitute Colorants and Their Properties
Although there is some agreement on the performance
characteristics of pigments (i.e., chemical compatibility, light and heat
fastness, hue, and intensity) which are of concern to most consumers (plastics
manufacturers), the selection of a substitute will depend in large part upon
the individual consumer's ranking of the importance of these attributes. For
example, a manufacturer of beach balls may worry mostly about hue and
intensity and not be concerned about heat fastness. On the other hand, a
manufacturer of high-performance automotive polymers may find a less vibrant
color acceptable if the substitute is heat-resistant and performs suitably in
the other areas.
Particular colorant-polymer combinations may also be ruled out for a
variety of other reasons. The first problem that might be encountered is a
chemical incompatibility between the colorant and the polymer solvent, resin,
or manufacturing by-products. For example, some pigments may not be used in
PVC because of their sensitivity to acid (Kirk Othmer 1983). In addition to a
chemical resistance problem, the colorant may not be able to survive harsh
processing conditions for certain polymer resins. For example, although the
end use of a plastic polymer may not require high temperatures, extensive
heating during processing is often required to melt and mold a plastic. In
addition to these obstacles, a colorant-polymer combination may be ruled out
because of the end use of the plastic product. A combination that is
sufficiently lightfast and suitable for indoor use may be ruled out for
exterior applications. Table 13 provides possible substitutes and their
performance properties for lead and cadmium pigments.
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For purposes of this analysis, potential substitutes for lead and
cadmium pigments are chosen based only on the characteristic of having a
similar hue as reported in the Plastic Additives Handbook (1987). Because
application-specific considerations are often critical for establishing exact
substitution patterns, lead- and cadmium-based pigments are grouped together
(i.e., substitutes are considered for the color yellow; not chrome yellow
(lead) and cadmium yellow). A potential substitute for each major hue (red
and yellow) was chosen from the chemical families that are comprised of
inorganic and organic pigments and dyes. In addition, two potential organic
substitutes, quinacridone and perylene pigments, were chosen based on
information from Mobay (1989) that reported they could be used with high
performance polymer systems (e.g., nylon, polyesters).
a. Costs of Lead- and Cadmium-based Pigments and Their
Potential Substitutes
For most of the lead-based and cadmium-based colorants, many
technically acceptable substitutes are available, although as mentioned above,
the costs of the substitutes may be significantly higher. The price of
cadmium has increased as other markets, such as that for nickel-cadmium
batteries, increase the demand for cadmium. On the other hand, lead pigments
have remained inexpensive. Table 14 shows recent prices for the most common
lead- and cadmium-based pigments, as well as prices for some pigments (mostly
organic) that could be used as substitutes in various applications.
According to one industry contact, as a rule of thumb, the performance
of organic pigments increases as the price does (Hoechst-Celanese 1989).
Certain pigments may not perform as well as less expensive organics in a few
measures of performance, but the quality must be higher in at least one aspect
of performance or there would be no demand for the product. For example,
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Tabla 13. Pobantial Substitutes for Lead and Cadmium Pigments and Their Performance Properties
Potential
Substitute Colorant
Hues
Heat
Stability*
CO
Opacity/
Lightfastnessb Hiding Power
Remarks on Performance0
(Compatible Polymer/Resin)
Possible Substitute For:d
Inorganic
Nickel titanium
Iron oxide
Yellow
Red
300
300
Opaque
Opaque
General suitability, but greatly
reduced tinting strength
General suitability, but only
in mixtures of dark shades
Lead chromate; cadmium sulfide;
cadmium sulfide + zinc
Lead molybdate; cadmium/sulfide selenide
H-PVC -
Organic
. Monoazo
Monoazo naphthol
Quinacridone
Perylene
Dyes
Pyrasolone derivative
Azo dye
Yellow 260
Red 280
Red 240-280
Red 220-300
Yellow 300*
Red 260*
7-8
5-7
7-8
7-8
7-8«
2-5«
Transparent LDPE, PS +; PVC -
Transparent PVC, PS, LDPE +; HOPE (+*)
Transparent PS, PVC, LDPE +; HOPE (+*)
Transparent PS, PVC, LDPE +; HOPE (+*)
Transparent PMMA, H-PVC, PS +
Transparent PMMA..H-PVC, PS +
Lead chromate;
cadmium/sulfide
Lead molybdate;
Lead molybdate;
Lead molybdate;
Lead chromate;
cadmium sulfide
Lead molybdate;
cadmium sulfide;
selenide
cadmium/sulfide selenide;
cadmium/sulfide selenide
cadmium/sulfide selenide
cadmium sulfide;
+ zinc
cadmium/sulfide selenide
For heat stability, the temperature is stated at which no coloristic changes occurred during normal dwell times (approximately 5 minutes) in processing machines.
D Determination of llghtfastness is carried out in accordance with DIN 53 389. 1 is the lowest value; * has 8 times the fastness level of 1; the highest value is 8,
testing not normally being carried out beyond this level. See Plastic Additives Handbook (1987) for more information.
e Polymer Codes:
PS - polystyrene; LDPE - low density polyethylene; EtWA - polymethyl methacrylate; HOPE - high density polyethylene; PVC - polyvinyl chloride;
H-PVC - Unplasticized PVC.
Polymer Performance: + denotes sultable/recoanended; - limited suitability/recommended; - denotes not suitable/reconnended; () denotes a qualification of the statement;
* denotes caution is needed in the case of HOPE articles sensitive to distortion.
* Possible substitutes were based primarily on colorant hue as reported in the Plastic Additives Handbook (1987).
For dyes, lightfastness and heat stability depends to an especially high degree on the plastic to be colored.
Source: Brannon 1*88, Plastic Additives Handbook 1987, Vinyl Institute 1989b.
- 31 -
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Table 14. Costs: Lead- and Cadmium-based Pigments
and Potential Substitutes
Cost
Hue ($/lb.)b
Yellow Lead/Cadmium Pigments
Lead chromate $ 1.55
Cadmium sulfide $14.60
Cadmium sulfide + zinc $14.60
Substitute Colorants*
Nickel titanium (inorganic) $ 3.50
Monoazo (organic) $17.95
Pyrazolone derivative (dye) $20.32
Red Lead/Cadmium Pigments
Lead molybdate $ 2.25
Cadmium/sulfide selenide $18.15
Substitute Colorants'
Iron oxide (inorganic) $ 0.79
Monoazo naphthol (organic) $24.25
Quinacridone (organic) $32.00
Perylene (organic) $41.20
Azo dye (dye) $10.30
Note: It has not been possible to establish the exact colorant to resin ratio
required to achieve equal coloring properties for potential substitute
products as compared to the lead- and cadmium-containing pigments. As a
result, it is not possible to develop a cost per pound of resin for
substitute products.
The substitute colorants listed are based on having a similar hue (i.e., red
or yellow) as reported in the Plastic Additives Handbook (1987). In addition
to cost, specific selection of a substitute is dependent on a diverse set of
performance properties. For a comparison of these properties, see Table 13.
b Costs were determined by contacting chemical companies and requesting prices
on given pigments (from Plastic Additives Handbook). The costs are based on
the most commonly used (standard) packaging sizes (40-60 Ib. containers)
reported by the chemical companies.
Sources: BASF 1989, Bayer-Mobay 1989, Plastic Additives Handbook 1987.
- 32 -
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prices generally increase as the acceptable processing temperatures rise.
This consideration, combined with the smaller production scales of specialty
and high-performance plastics help maintain the price differential.
In addition, the amount of product used for an application is dependent
mainly on the shade and brilliance required. For example, if a faint yellow
is required, less lead chromate is used than would be required for a darker
yellow. In general, for similar hues, 25 percent less organic pigment by
volume is required compared to an inorganic pigment (Hoechst-Celanese 1989).
Estimates are not available as to the amount of dye required for coloring.
b. Other Factors Affecting Selection of Substitutes and
Substitute Costs
If lead and cadmium pigments were not available, chemical
companies may be more willing to invest in the research and development of
substitutes, because there would be less low-cost competition for any new
substitutes developed. From Table 13, it is evident that there are many
substitutes available for lead and cadmium pigments; however, it may be
impossible to find exact replacements for some pigments (such as some of the
very high- performance cadmiums used in nylons) at any cost. In those cases,
it may be necessary for the plastic manufacturer to sacrifice one aspect of
performance, such as hue or brilliance, in exchange for another, such as heat
or lightfastness.
Several of the companies contacted (Harshaw 1989, Heubach 1989) are still
committed to the manufacturing and/or distribution of lead-based pigments, but
the majority of the companies contacted have ceased to supply them. The same
cannot be said for some of the cadmium-containing colorants; their performance
characteristics are more difficult to reproduce using either organic or other
inorganic pigments. Although there are organic pigments which match cadmium
- 33 -
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pigments in brilliance, hue, and lightfastness, they generally are not
adequate in high-temperature situations. On the other hand, although many of
the inorganic compounds are quite heat resistant, they are tinctorially weak
or colorless (white).
The toxicity of heavy metals is well known, and therefore many
manufacturers have shied away from using compounds containing metals such as
lead and cadmium. For example, General Electric stopped using lead pigments
approximately 10 years ago and ceased use of cadmium pigments at the beginning
of 1989 (General Electric 1989).
Research by many other manufacturers continues in order to find potential
substitutes for lead and cadmium compounds that are compatible with high-
performance engineering resins such as polycarbonate, nylon, and other
polyesters (Modern Plastics 1987). Combinations of substances are sometime*
used to complement each other and improve the overall qualities of products.
For example, in an application requiring some hiding power and resistance to
heat, a mix of a high performance organic colorant and an inorganic compound
may work. The inorganic pigment lends its hiding power while the organic
provides intense color. In some instances the inorganic compound may also
provide some color, thereby reducing the need for large quantities of organic
colorant, which would be required if the inorganic pigment were colorless
(white) like titanium dioxide.
Although dyes can often be used in place of pigments, they currently do
not hold a large share of the market for colorants. Because dyes must be
soluble in the resins they are used in, each variety of dye may be compatible
with only a few types of resins. In addition, the lead- and cadmium-based
pigments are generally applied in a solid form, either as color concentrates
or dry powders. Although dyes are also found in solid form, they are usually
- 34 -
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used as liquids which would require some changes in the plant equipment and
result in additional costs to the plastic manufacturer.
2. Potential Substitute Stabilizers and Their Properties
Potential substitute products that could replace lead- and cadmium-
containing heat stabilizer products have been developed and continue to be
investigated for several reasons. The toxicity of lead and cadmium compounds,
the availability of an increasing number of technically superior alternate
products, the lower costs of substitutes, and increasing costs associated with
using lead and especially cadmium products have all been influencing factors.
This section addresses potential substitute products, compares costs to
existing lead and cadmium products when possible, and discusses important
factors that affect substitution.
The majority of lead-based heat stabilizers have been replaced in
applications where substitution is technically and/or economically feasible.
For example, organotin stabilizers (e.g., alkyltin mercaptides, alkyltin
carboxylates, and estertin mercaptides), barium/zinc, and metal-free
stabilizers can be used in rigid applications, pipes and fittings, pigmented
profiles, foamed profiles, and phonograph records that previously used lead-
based products (Argus 1989c). Table 15 identifies PVC articles and stabilizer
systems that can replace lead-based products in rigid PVC applications
(Plastics Additives Handbook 1987).
Lead stabilizers also have been used in flexible PVC applications. These
applications can be split into those for which cost-effective and reliable
substitutes have been developed (shoes, sandals, and soles), and those for
which substitution has lagged (electrical insulation and jacketing).
Electrical insulation applications appear to use the majority of lead-based
- 35 -
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Table 15. Potential Substitutes' for Lead-based Heat Stabilizers
in Rigid PVC Products
Methyl, Butyl Metal-
and/or Octyltin Butyltin Free
PVC Item Mercaptides Esters Stabilizers
Pipes and Fittings X
Pigmented Sheets and
Profiles X X
Foamed Profiles X
Phonograph Records X
Ba/Cd stabilizers are not considered to be substitutes for lead stabilizers
due to toxicity considerations and the scope of this analysis (i.e., lead and
cadmium products are both under investigation and therefore are not considered
to be substitutes for one another), although they may be technically and
economically feasible in some applications.
b Phonograph records may be stabilized with certain metal-free stabilizers.
Source: Plastics Additives Handbook 1987.
- 36 -
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stabilizers because of the critical non-conducting nature of lead products
(Vinyl Institute 1989a).
The use of electrical cable insulation and jacketing can be divided
among three major use areas:
power wiring,
telephone cable, and
cords and connectors for appliances and
other consumer items.
The critical properties of weathering, humidity resistance, and thickness of
the jacket in the power wiring and telephone cable applications have made
substitution difficult given that lead imparts these properties. Lead heat
stabilizers for these applications provide outstanding use characteristics and
there currently are no products available on the market that can replace the*e
lead-based products (BF Goodrich 1989).
The power and telephone cable uses account for about 50 percent of lead
stabilizer usage for jacketing and insulation, while the cord/connector
applications account for the remaining 50 percent. It is believed that these
lower performance cord/connector applications can be replaced with alternate
stabilizers (Argus 1989c, BF Goodrich 1989). The reformulated products were,
however, too experimental or could not be identified at this time.
Teflon* is a technically feasible substitute for PVC coatings, but is
not a one-for-one substitute in that heat stabilizers are not replaced, but
rather reformulation is required (i.e., Teflon* replaces PVC not lead). The
use of Teflon* has not been examined by the industry as a viable replacement
for cable insulation and is expected to be on the order of five to ten times
more expensive (Bedford Chemical 1989). Teflon* also may not possess
sufficient flexibility for many applications (Vinyl Institute 1989b).
- 37 -
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Table 16. Potential Substitutes' for Lead-based Heat Stabilizers
in Flexible PVC Products
Ba/Zn Butyltin
PVC Item Stabilizers Esters
Cable Insulation and
Jacketingb
Shoes, Sandals,
Soles
Note: Ba - barium; Zn - Zinc
' Barium/cadmium stabilizers are not considered to be substitutes
for lead stabilizers due to toxicity considerations and the scope
of this analysis (i.e., lead and cadmium products are both under
investigation and therefore, are not considered to be substitutes
for one another), although they may be technically and
economically feasible in some applications.
b Teflon* is a technically feasible substitute for PVC coatings,
but is not a one-for-one substitute in that heat stabilizers are
not replaced, but rather reformulation is required (i.e., Teflon*
replaces PVC not lead). The use of Teflon* has not been examined
by the industry as a viable replacement for cable insulation and
is expected to be on the order of five to ten times more expensive
(Bedford Chemical 1989). Teflon* also may not possess sufficient
flexibility for many applications (Vinyl Institute 1989b).
Sources: Argus 1989c, Bedford 1989, Plastic Additives Handbook 1987.
- 38 -
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Table 16 identifies the potential substitutes for lead-based stabilizers used
in flexible PVC applications.
Barium/Cadmium heat stabilizers have a wide range of applicability in
rigid and flexible PVC applications. The products and potential substitutes
are identified in Tables 17 and 18. There is some overlap with lead-based
stabilizers, but these are not considered to be substitutes for cadmium-
containing products and vice-versa. The processing techniques (e.g.,
calendaring, extrusion, injection molding, blow molding, pressing, coating),
the processing conditions (temperature, mixing, alkalinity) and a host of
other reasons, including the presence of other additives, the end use of the
product (indoor/outdoor), and the costs of potential substitutes, influence
which products are ultimately considered to be substitutes. In general, thete
are adequate substitutes for cadmium-containing stabilizers, including
barium/zinc, calcium/zinc, and tin-based stabilizers.
a. Costs of Lead- and Cadmium-based Heat Stabilizers and
Potential Substitutes
Lead and cadmium heat stabilizers have seen widespread use
because of their relatively low cost compared to newer substitute products.
As concern has mounted regarding the toxicity of lead and cadmium products,
substitute products have been perfected and costs of substitutes have declined
(Argus 1989b). Table 19 presents the relative costs of lead, cadmium,
substitute products.
It must be noted that the actual substitution pattern for lead and
cadmium stabilizers is very complicated. The wide range of applications,
processing considerations, and other factors that affect potential substitute
development and entry into the market make it difficult to distinguish exact
- 39 -
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Table 17. Potential Substitutes" for Cadmium-based
Heat Stabilizers in Rigid PVC Products
Barium/
Butyltin Butyltin Zinc
PVC Item Mercaptides Esters Solids
Films for Non-food Applications X X
Pigmented Profiles
- - Indoor X X
- - Outdoor X X
Foamed Profiles X X
Lead stabilizers are not considered to be substitutes for Ba/Cd
stabilizers due to toxicity considerations and the scope of this analysis
(i.e., lead and cadmium products are both under investigation and therefore,
are not considered to be substitutes for one another), although they may be
economically and technically feasible in some applications.
Source: Plastic Additives Handbook 1987.
-------
Table 18. Potential Substitutes* for Cadmium-based
Heat Stabilizers in Flexible PVC Products
Butyltin Barium/ Calcium/
Mercaptides Zinc Zinc
PVC Item or Esters Stabilizers Stabilizers
Films for Non-food
Applications X XX
Profiles and Flexible
Tubes for Non-food
Applications X X
Shoes, Sandals and
Soles x
Artificial Leather
Coatings x X
Dippings X X
a Lead stabilizers are not considered to be substitutes for Ba/Cd
stabilizers due to toxicity considerations and the scope of this analysis
(i.e., lead and cadmium products are both under investigation and therefore,
are not considered to be substitutes for one another), although they may be
economically and technically feasible in some applications. The relative
amount of cadmium in liquid stabilizers can be reduced by the addition of zinc
fatty acid salts that replace the corresponding cadmium salts (Modern Plastics
1987).
Source: Plastic Additives Handbook 1987, Vinyl Institute 1989b.
41 -
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Table 19. Costs of Lead, Cadmium, and Potential Substitute Heat Stabilizers
Stabilizer Class
Lead
Lead compounds
Organotin stabilizers
Barium/zinc stabilizers
Teflon*
Cadmium
Barium/cadmium liquids
Barium/cadmium solids
Barium/cadmium/zinc products
Zinc/calcium products
Liquid organotin stabilizers
Solid organotin stabilizers
Barium/zinc liquids
Barium/zinc solids
Approximate
Cost Range
0.50-1.00
1.00-3.00
2.00-4.00
a
0.95-1.75
1.85-2.75
0.95-1.70
1.00-3.00
3.00-4.50
8.00-10.00
1.25-2.50
2.00-4.00
Amount Used Per
Hundred Parts of Resin
1.0-3.0
1.5-2.5
1.5-3.0
Not Applicable
1.0-4.0
1.5-3.0
1.0-3.0
1.0-3.0
2.0-4.0
1.5-3.0
1.0-4.0
1.5-3.0
Teflon* is a different class of substitute in that it would replace the
end product, PVC coatings, used for wire and cable insulation. It is not
currently considered a stable substitute for economic reasons. The cost of
PVC coatings is roughly $0.50 to $1.00/lb. and for Teflon* >$5/lb.
Sources: Argus 1989a, 1989b, 1989c; Bedford 1989.
-------
substitution patterns. The costs presented in Table 19 should be considered,
therefore, rough approximations.
b. Other Factors Affecting Selection of Substitutes and
Substitute Costs
There are a number of considerations that must be included
in the selection of stabilizer substitutes and estimation of costs for
comparison to costs for lead and cadmium stabilizers. It has not been
possible to characterize each of these considerations, but they are provided
for completeness:
Potential substitute stabilizer packages that can replace lead or
cadmium products may be required in quantities greater or lesse'r
than the products they replace. They may be cheaper or more
expensive, at the concentration level required, or they may be
viable only for some applications.
The addition of co-stabilizing* products may reduce potential
substitute costs, improve performance to a level above that of the
lead or cadmium product, or increase product service life.
It may be possible to combine stabilizers so that a synergistic
effect is achieved, thereby improving performance and/or reducing
costs.
New potential substitutes are constantly being developed and made
available. Some of these, based on antimony and metal-free
stabilizer systems (e.g., diphenylthioureas, and S-
aminocrotonates) have not been widely accepted, but may influence
the stabilizer market over the next few years.
* Co-stabilizers are usually organic compounds that enhance the solvency
of stabilizers or provide some other benefit, but are not stabilizers if used
alone.
43 -
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E. References
Argus. 1989a (May 10). M. Croce. New York, NY. Transcribed telephone
conversation with Mark Wagner, ICF Incorporated, Fairfax, VA.
Argus. 1989b (May 11). D. Stimpfl. New York, NY. Transcribed telephone
conversation with Mark Wagner, ICF Incorporated, Fairfax, VA.
Argus. 1989c (May 17). D. Brilliant. New York, NY. Transcribed telephone
conversation with Mark Wagner, ICF Incorporated, Fairfax, VA,
BASF. 1989 (May 16). Basic Organics Group. Transcribed telephone
conversation with Tanya Yudleman, ICF Incorporated, Fairfax, VA.
Bayer-Mobay Corporation. 1989 (May 16). Transcribed telephone conversation
with Tanya Yudleman, ICF Incorporated, Fairfax, VA.
Bedford Chemical. 1989 (May 4). D. Gauw. Bedford Chemical, Division of
Ferro Corporation. Bedford, OH. Transcribed telephone conversation with Mark
Wagner, ICF Incorporated, Fairfax, VA.
Brannon, SM. 1988 (February 1-5). 43rd Annual Conference, Composites
Institute, the Society of the Plastics Industry. Colorants for Composites --
A Review.
EPA. 1989 (January). U.S. Environmental Protection Agency. Characterization
of Products Containing Lead and Cadmium in Municipal Solid Waste Facilities
1970 to 2000. Prepared by Franklin Associates Ltd., Prairie Village, KS.
Franklin Associates. 1990 (August). Characterization of Lead in Plastic
Products in Municipal Solid Waste, 1970 to 2000. Prairie Village, KS.
General Electric Color Lab. D. Bryant. 1989 (May 4). Transcribed telephone
conversation with Peter Weisberg, ICF Incorporated, Fairfax, VA.
B.F. Goodrich. 1989 (May 17). G. Lefebvre. Cleveland, OH. Transcribed
telephone conversation with Mark Wagner, ICF Incorporated, Fairfax, VA.
Harshaw Colors. 1989 (May 12). M. DiLorenzo. Division of Eagelhard Corp.
Transcribed telephone conversation with Don Yee, ICF Incorporated, Fairfax,
VA.
Heubach, Inc. 1989 (May 12). Transcribed telephone conversation with Don
Yee, ICF Incorporated, Fairfax, VA.
Hoechst-Celanese. 1989 (May 9). D. Wave. Transcribed telephone conversation
with Don Yee, ICF Incorporated, Fairfax, VA.
Kirk-Othmer. 1983. Encyclopedia of Chemical Technology. John Wiley and Sons
Publishing Co., Inc. Vol. 18, pp. 184-206; Vol. 14, pp. 168-183; Vol. 6.
Mobay. 1989 (May 3). J. Graff. Transcribed telephone conversation with Don
Yee, ICF Incorporated, Fairfax, VA.
- 44 -
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Modern Plastics. 1982 (July). McGraw-Hill Publishing Co., p. 44.
Modern Plastics. 1983 (September). Chemicals and Additives Special Report.
McGraw-Hill Publishing Co.
Modern Plastics. 1985 (September). Chemicals and Additives Special Report.
Colorants -- pp. 60-62; Heat Stabilizers -- pp. 68-69. McGraw-Hill Publishing
Co.
Modern Plastics. 1987 (September). Colorants -- pp. 68-71; Heat Stabilizers
--pp. 70-71. McGraw-Hill Publishing Co.
Modern Plastics. 1988 (September). Chemicals and Additives Special Report.
McGraw-Hill Publishing Co.
Modern Plastics. 1989 (January). Resin Report. McGraw-Hill Publishing Co.
Plastics Engineering Handbook. 1987. 4th Edition. Van Nostrand Reinhold
Publishing Company.
Plastic Additives Handbook. 1987. Hanser .Publishers. Munich, Germany.
t
Radian. 1987. Chemical Additives for the Plastics Industry. Radian
Corporation. Noyes Data Corporation. Park Ridge, NJ.
Vinyl Institute. 1989a (May 15). R. Gottesman. Little Falls, NJ.
Transcribed telephone conversation with Mark Wagner, ICF Incorporated,
Fairfax, VA.
Vinyl Institute. 1989b (July 11). R. Gottesman. Comments received on the
Draft Plastics Section.
Yost, K. and K. Greenkom. 1984 (January). Source Specific Impacts and
Exposure Mechanisms for Cadmium. Purdue University.
- 45 -
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III.
A. Overview of the Pigment Industry
A pigment can be defined as a substance that imparts color to other
materials. Depending on the size of the pigment particles, different
wavelengths of light can be selectively absorbed thereby producing a desired
color. Pigments are normally insoluble in the medium that they are dispersed.
Pigments are often chosen for incorporation into a final product based on
tinctorial strength, brightness, texture, durability, and cost. Pigments are
usually classified as being inorganic or organic. Organic pigments by
definition contain carbon.
B. Uses of Lead- and Cadmium-containing Pigments
t
Pigments are used in a wide variety of products: in paints and inks; atf
to color plastics, paper, rubber, and glass. Although the use of lead- and
cadmium-containing pigments in plastics is representative of their use in the
other use areas discussed in the EPA 1989 report, certain properties such as
heat resistance may be more important in other use areas such as glass and
ceramics. For a discussion of the uses of lead- and cadmium-containing
pigments refer to Chapter II on plastics.
C. Consumption of Lead and Ca^ium in Pirments
Lead and cadmium-containing pigments are used in plastic, glass/ceramic,
and rubber products that are disposed in municipal solid waste facilities.
The consumption of lead and cadmium in pigments is discussed in Section C of
Chapter II on plastics, Chapter VI on glass, and Chapter XI on rubber. The
tables are repeated here for ease of reference.
D. Potential Substitutes of Lead- and Cadmium-containing P^jp^nts
The potential substitutes for lead- and cadmium-containing pignwnts are
discussed in Section D of the Plastics Chapter (Chapter II). The potential
- 46 -
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Table 20. Discards of Lead in Pigments for Plastic in MSW
Lead in Total Resin Discarded
Pigments Discarded* in Nonfood Applications1*
Year (tons) (thousands of tons) Lead/Resin Ratio
1970
1975
1980
1986
647
813
967
990
2,061
3,098
5,103
8,111
0.00034
0.00026
0.00019
0.00012
Note: The term resin refers to the type of plastic. Practically, plastics are
classified by the nature of the major resin(s) used in their
manufacture. The resins included in this consumption table could
include all of the resins identified in Table 2.
Adjusted for net exports and with manufacturing losses estimated to be 2
percent; although the source discusses cadmium pigments, lead based pigments
are found in similar forms, and therefore similar losses are expected (Yost
and Greenkorn 1984).
b Total resin figure includes resins containing no lead-based pigments.
Source: EPA 1989.
- 47 -
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Table 21. Discards of Lead in Pigments in Rubber Products in MSW
Discards of Discards of Total Discards
Lead in Lead in Fabricated of Lead in
Tire Pigments Rubber Products Rubber Pigments'
Year (tons) (tons) (tons)
1970
1975
1980
1986
45
44
83
56
16
15
33
21
52
53
104
70
Ten to fifteen percent of tires and other rubber products are
diverted or recovered annually.
Source: EPA 1989.
- 48 -
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Table 22. Discards of Lead in Pigments in
Ink and Miscellaneous Products in MSW
Year
Discards of
Lead in
Ink Pigments*
(tons)
Discards of
Lead in All
Other
Miscellaneous
Pigments'5
(tons)
Total Discards
of Lead in Ink
and Miscellaneous
Pigments
(tons)
1970
1975
1980
1986
19,192
13,819
8,222
265
7,828
3,198
1,642
866
27,020
17,017
9,864
1,131
Note: Total consumption includes only pigments
other than those found in plastics,
rubber, glass, and ceramic glazes.
a Based on net consumption of lead in inks, assuming 5
percent manufacturing losses and adjusted to exclude
inks in recycled papers.
b Includes pigments in textiles, adhesives, artists'
paints, and miscellaneous applications.
Source: EPA 1989.
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Table 23. Discards of Cadmium in Pigments in Plastic in MSW
Cadmium in Total Resin Discarded
Pigments Discarded" in Nonfood Applications11
Year (tons) (thousands of tons)
Cadmium/Resin Ratio
1970
1975
1980
1986
162
256
259
259
2,061
3,098
5,013
8,111
0.000079
0.000083
0.000052
0.000032
Note: The term resin refers to the type of plastic. Practically,
plastics are classified by the nature of the major resin(s) used
in their manufacture. The resins included in this consumption
table could include all of the resins identified in Table 2.
a Adjusted for net exports and with manufacturing losses assumed to be 6
percent (Yost and Greenkorn 1984).
b Total resin figure includes resins containing no cadmium-based pigments,
Source: EPA-1989.
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Table 24. Discards of Cadmium in Pigments for Glass, Ceramics, and
Miscellaneous Products in MSW
Year
Cadmium
Discarded in
Pigments for
Glass and Ceramics'
(tons)
Cadmium Discarded
in Pigments for
Miscellaneous Products'5
(tons)
Total Discards of
Cadmium in Pigments
for Glass, Ceramics
and Miscellaneous
Products0
(tons)
1970
1975
1980
1986
32
27
23
29
79
65
56
70
111
92
79
99
a Half of the glass and ceramics with cadmium pigments are assumed to
end up in MSW. Discards are assumed to be in the year of manufacture
for the glass product.
b Includes pigments in products other than plastics, rubbers, and
glass/ceramics. Products are assumed to be discarded in the year of
manufacture.
c Includes pigments other than those found in rubbers and plastics.
Source: EPA 1989.
- 51 -
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Table 25. Discards of Cadmium in Pigments
for Rubber Products in MSW
Cadmium in Pigments
for Rubber-Products*
Year (tons)
1970 10
1975 13
1980 8
1986 6
* Consumption of cadmium pig-
ments in rubber was assumed to
be one percent of total con-
sumption of cadmium pigments.
Source: EPA 1989.
- 52 -
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substitutes for these pigments used in glass/ceramic* and rubber products are
assumed to be similar to those discussed in the plastics chapter.
E. References
EPA. 1989 (January). U.S. Environmental Protection Agency. Characterization
of Products Containing Lead and Cadmium in Municipal Solid Waste Facilities
1970 to 2000. Prepared by Franklin Associates Ltd., Prairie Village, KS.
Yost, K. and K. Greenkorn. 1984 (January). Source Specific Impacts and
Exposure Mechanisms for Cadmium. Purdue University.
* Pigments are used in glazes and enamels. Glazes and enamels are
discussed in the glass/ceramic chapter (Chapter VI). The consumption of lead
pigments used in glass products is not available. The EPA 1989 report
identifies lead consumption in glass only at the aggregated level. The
proportion of this total lead use that is attributable to lead pigments is.
therefore, not available.
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IV. SOLDER
A. Overview of the Soldering Industry
Solder is used in a variety of products to form both electrical and
structural bonds between various types of materials.* The most common use of
solder is to attach electrical components to printed circuit boards (Arconium
1989). The soldering process is useful in that it allows manufacturers to
easily automate the simultaneous attachment of multiple components. The major
markets for these printed circuit boards are in computers, communication
devices, and government/military uses. It should be noted that the products
discussed in this chapter are those that are disposed of in municipal solid-
waste (MSW) and therefore, may exclude certain applications. For example,
solder is used in the manufacture of automobile bodies and automobile parts
that are assumed to be disposed in other types of waste facilities (EPA 1989J.
The soldering process is defined as a metallurgical joining method using
a filler metal (the solder) with a melting point below 600°F (316*C).
Soldering relies on wetting** for the bond formation and does not require
diffusion* with base metals to achieve bonding (Manko 1979). The limit of
600*F was set arbitrarily; many people consider 800'F (427°C) the upper
Both electrical and structural bonds join parts physically. Unlike an
electrical bond, however, a structural bond is not required to transmit
electricity.
"Wetting" describes the relationship between molten solder and the
surfaces of materials that are being soldered. Solder with good wetting
ability forms intimate continuous contact with the materials to be soldered.
In the context of bonding, "diffusion" means the joining of parts by
melting them together. Under certain chemical conditions, the materials in
soldered parts can also diffuse into each other without being heated.
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temperature limit for soldering.* Soft solders are characterized by melting
temperatures below 375eF, while hard solders melt between 375T and 800*F
(Manko 1979, Belser 1954).
1. Solder Characteristics
Solder is available in a wide variety of compositions and forms,
but is almost always an alloy composed of two to six types of metal.** While
tin and lead are the most common elements found in solder, solder alloys can
also include indium, bismuth, cadmium, antimony, silver, gold, zinc, copper,
mercury, gallium, germanium, aluminum, arsenic, and silicon. (Indium 1988,
Manko 1979, Alpha Metals 1989, Warwick 1985). The most common type of solder
used in consumer electronics, however, is tin/lead solder (Kapp 1989).
B. Solder Use Areas
While solder is used in a wide variety of military, industrial, and
commercial products, this report addresses only the use of solder in consumer
(commercial) products that are disposed of in MSW facilities. Three solder
use areas in consumer products have been identified: consumer electronics,
light bulbs, and cans (for food and non-food products).
1. Consumer Electronics
Consumer electronics disposed of in MSW facilities include
products such as televisions, radios, and video cassette recorders. This
report assumes that all of the solder found in consumer electronics is used to
* The upper temperature limit of soldering separates soldering operations
from brazing operations. While both bonding operations rely on a filler
metal, brazing is done at a temperature level sufficient to partially melt the
base metals to help form the bond.
** Most solder alloys contain only two or three types of metal (Indium
Corporation of America 1988).
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make electrical bonds in printed circuit boards in these electronic devices.*
In 1986, consumer electronics accounted for 11.7 percent of the printed
circuit market (EPA 1989).
Although home computers are a popular type of solder-containing consumer
product, the printed circuit boards found in home computers are not usually
disposed of in MSW. Instead, these circuit boards are removed for repair and
returned to manufacturers for recovery of components such as memory chips (EPA
1989). Therefore, this report assumes the home computer circuit boards become
industrial waste rather than MSW. This report also assumes consumer
communications equipment (e.g., telephones) enters industrial waste rather
than MSW (EPA 1989).
The chief reason tin/lead solder is used to produce consumer electronics
is cost (Talco 1989). Because specialty solders employ more exotic metals,
the tin/lead alloy can be many times cheaper than a substitute solder.
Tin/lead solder also has advantageous physical properties --it has good
wicking tendencies;** has some pliancy to resist breakage from vibration,
bonds aggressively at a relatively low temperature, which avoids the
possibility of thermally shocking the parts to be soldered; and it has good
electrical continuity (IPC 1989b, Sylvania 1989a). Tin/lead solder also works
well in the manufacture of solder clad printed circuit boards (printed circuit
board manufacturing is discussed below).
Cadmiua-containing solder is not commonly used to manufacture consumer
electronics. Manufacturers avoid the use of cadmium because of health-related
* This assumption is based on the methodology found in EPA 1989 report.
** The "wicking" ability of solder is its tendency to produce strong
bonds by travelling up the holes used to mount components on some printed
circuit boards.
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concerns including the generation of poisonous fumes during the soldering
operation (IPC 1989b, Keeler 1987, Indium 1989d).
a. Through-hole and Surface Mount Printed Circuit Boards
Two technologies can be used to attach electrical components
to printed circuit boards -- through-hole assembly technology or surface mount
assembly technology. With surface mount technology (SMT), components are
attached directly to the board without drilling or punching holes (see Figure
1). Without holes, components can be densely packed on the board thereby
reducing the size of the board. Texas Instruments cites a 40 percent
reduction in size of the printed circuit board assembly over through-hole
technology when surface mount technology is used (Mullen 1984).
With through-hole technology, the leads of the electrical components are
placed into holes that have been drilled in the circuit board (see Figure 1);
Usually the circuit board is soldered on the side of the board from which the
leads protrude (IPC 1989c).
b. Printed Circuit Board Manufacturing
There are several methods used to manufacture the circuit
board to which components are attached. The oldest technique is called
"subtractive" and can be used to make either single- or double-sided circuit
boards.* The process begins with a copper clad circuit board in its initial
state -- a laminate such as fiberglass or epoxy that has been coated with
copper on on* or both sides. A protective pattern of "etch resist" is
deposited on the copper surface, and the unwanted copper is etched away (hence
the name "subtractive"). The subtractive process can be further categorized
according to the type of etch resist used (Manko 1986).
* A single-sided board can accept components on only one side, while a
double-sided board can accept components on both sides.
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i) DIP Through-hole Component.
ii) SMC J-lead Surface-Mount Component.
Figure 1. Comparison of Through-Hole and Surface Mount Technologies
(Source: Mullen 1984.)
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The most common subtractive method used to produce double-sided and
multilayer boards employs tin/lead plating as the etch resist. The first step
involves coating the board with organic resist in a negative image of the
circuit pattern. Next, tin/lead is applied with an electroplating process to
create a positive image of the circuit pattern. The organic resist and the
copper are then stripped, leaving a copper circuit pattern protected by the
tin/lead plating (Manko 1986, IPC 1989c). This method of circuit board
production can be used for through-hole and surface mount assemblies.
The advantage of tin/lead plating is that it protects the copper from
oxidizing, allowing the circuit board to be stored for long periods (IPC
1989b). The use of tin/lead clad circuit boards encourages the use of
tin/lead solder during assembly of the printed circuit board because the
solder blends with the alloy already plated on the circuit board. The use of
a different solder alloy, while possible, can lead to problems as the
resulting solder alloy will be an unknown and possibly weak or low-melting
composition. Unfortunately, most of the desirable alloys for soldering are
not suitable for electroplating, making their use more difficult (Manko 1986).
Circuit boards may also be manufactured with a "print and etch" or an
"additive" process resulting in printed circuit boards with bare copper that
needs to be protected from oxidation. Organic coatings can be applied over
the copper to provide good protection for several months, but this oxidation
protection method does not last as long as a tin/lead coating that can protect
boards from oxidation for periods of 2-3 years (IPC 1989b).
2. Cans for Consumer Uses
Cans may be categorized as one of two types -- a two piece can or
a three piece can. A two piece can consists of two pieces --a cup-shaped
bottom and a top. The bottom of a two piece can is seamless and the top is
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always attached by crimping without the use of solder. A three piece can
consists of three pieces -- a top, bottom, and the cylindrical middle piece.
Three piece cans have a seam down the side that must be sealed (CMI 1989b).
Cans used in consumer applications can be grouped into three major
categories: food, beverage, and non-food (general packaging) cans. Non-food
cans are used primarily for aerosol products (CMI 1989a).* Virtually all
beverage cans are two piece cans that do not require solder for manufacturing.
Some food and non-food cans, however, do contain solder to seal the can
seams.
The small number of food cans that are currently manufactured with
solder employ solder that does not contain lead (with the possible exception
of cans containing dry foods such as coffee that will not leach lead into the
product). Some imported food cans, however, may contain lead solder (NFPA
1989b). Non-food cans (such as those used for aerosols) may also use lead-
containing solder (CMI 1989a, NFPA 1989a).
Lead solder is used in cans because of its low cost and because its low
melting temperature makes it easy to work with. Cadmium-containing solder is
not used in the manufacture of cans (CMI 1989b).
3. Light Bulbs
Consumer light bulbs can be grouped into two major categories--
incandescent and fluorescent. Solder is used only in the manufacture of
incandescent bulbs. Tin/lead solder is used in one of the final steps in the
manufacture of incandescent bulbs when the ends of the filament wire that
Aerosol products account for approximately two thirds of non-food
cans. Other non-food cans include paint, varnish, and automotive product cans
(CMI 1989a).
Only 3 percent of all food cans contain solder (CMI 1989b).
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protrude from the threaded end of the bulb are soldered to the small metal tab
at the base of the light bulb. Soldering not only prevents the filament wire
from snapping off during use, it also enhances the ability of the filament to
make good contact in the light socket (Sylvania 1989a).
Tin/lead solder is used to manufacture light bulbs for several reasons.
It is a low cost solder and melts at a relatively low temperature. The low
melting temperature of tin/lead solder is critical in light bulb manufacturing
as soldering is a final operation that could destroy the quality of the bulb
if the bulb glass is allowed to heat up to the point where it will release C02
and water into the light bulb assembly. Tin/lead solder also works fast and
bonds parts together aggressively (Sylvania. 1989a).
C. Consumption of Lead and Cadmium in Solder
Lead is used in solder for the manufacture of consumer electronics,
cans, and light bulbs. Although specialty solders that do not contain lead
can be used to manufacture these items, lead-containing solders dominate the
solder market (Talco 1989).
1. Consumption of Lead in Solder
Eutectic* tin/lead alloy (63 percent tin/37 percent lead) is the
most common soldering alloy currently in use (Kapp 1989). Almost all the lead
used to solder consumer electronics, cans, and light bulbs is contained in
tin/lead solder (Sylvania 1989a, Talco 1989, CMI 1989b). The amount of lead
used to manufacture and subsequently discarded in MSV for each of these items
A eutectic solder is an alloy of a certain composition such that it
melts at the lowest temperature of any alloy containing the metals involved.
This allows the alloy to melt at a specific temperature. Most alloys melt
over a temperature range and have a "mushy" state between the solid and liquid
states.
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is presented in Table 26. All of the lead consumption presented in this table
is attributable to the use of lead-containing solder (EPA 1989).
a. Consumer Electronics
The amount of lead consumed in consumer electronics has
increased steadily from 1970 to 1986. Consumer electronics were the fourth
largest contributor of lead in MSW in 1970, but by 1975 they were the second
largest contributor, a position they continue to hold (EPA 1989). The Bureau
of Mines, however, reports a general decline in the use of lead in solder in
electronic devices. Discards of lead in printed circuit boards found in
consumer electronics are projected to decline to less than 1,000 tons and less
than 1 percent of total discards by 2000 (EPA 1989). Because virtually no
cadmium is consumed in solder in the manufacture of consumer electronics,
cadmium-containing solder is not treated in this discussion (IPC 1989b).
b. Cans for Consumer Uses*
Solder is used in the manufacture of three piece cans to
form bonds along the seams. Due to consumer law suits and pressure from the
Food and Drug Administration, however, the use of lead-containing solder to
manufacture cans used for food and beverage products has declined
significantly over the past ten years (CMI 1989a). Lead-containing solder is
still used to manufacture non-food containers and some cans for dried food
(such as coffee) that cannot leach lead, but this application accounts for a
small amount (approximately 3 percent) of total can production (NFPA 1989a,
CMI 1989b). The sharp decline in the use of lead-containing solder to
manufacture food cans is reflected in Table 26, as indicated by discard
* Cadmium-containing solder is not used in the manufacture of cans
(Elkins 1989).
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Table 26. Discards of Lead in Solder in MSW
Discards of Lead Discards of Total
in Solder from Discards of Lead in Lead in Discards
Containers Solder from Solder from of Lead in
and Metal Cans' Consumer Electronics1" Light Bulbs0 Solder
Year (tons) (tons) (tons) (tons)
1970
1975
1980
1986
24,117
20,122
9,675
2,052
1,417
1,759
3,441
6,092
156
161
197
225
25,690
22,042
13,313
8,369
* Metal cans are assumed to be discarded in the year of manufacture.
Containers are assumed to last 3 years. All cans are assumed to go into MSW,
but only 20 percent of containers. Adjustments were made for recycling, which
constituted 2, 3, 5, and 4 percent of all discards in 1970, 1975, 1980, and
1985 respectively. These assumptions and adjustments reflect the methodology
found in the EPA 1989 report.
b Consumer electronics are assumed to have a product life of 8 years. This
category includes the circuit boards and chassis of electronic equipment.
0 Light bulbs are assumed to be discarded one year after manufacture.
Although some newer bulbs have longer lifespans, discards of solder from light
bulbs increased due to the continued use of shorter lifespan bulbs employed
for cost reasons and because of the increased number of incandescent lamps in
use (Roach 1989).
Source: EPA 1989.
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figures for lead-containing solder that have dropped by a factor of 12 between
1970 and 1986.
c. Light Bulbs
Light bulbs are not a large source of lead solder in MSW,
but are of interest because they contain two sources of lead -- solder and
leaded glass. The discards of lead in light bulbs shown in Table 26 addresses
only lead solder. Because the manufacture of fluorescent bulbs does not
require solder, the consumption figures address only the manufacture of
incandescent bulbs (EPA 1989).
Although lead-containing solder consumption in light bulbs has not risen
as fast as consumption in consumer electronics, 1986 consumption is about 40
percent higher than 1970 consumption. In the past, cadmium solder was used in
the manufacture of light bulbs. Virtually all bulbs made today, however,
contain tin/lead solder. Solder used in light bulb manufacturing contains
about 70 to 80 percent lead to keep solder costs down. Lead is relatively
cheap and the metallurgy of the solder in this application is not critical
(Indium 1989e). Cadmium-containing solders are no longer used to make light
bulbs (Sylvania 1989a).
d. Plumbing Solder
Until recently, tin/lead solder was the most commonly used
alloy for soldering plumbing. Recent legislation promulgated under the Safe
Drinking Water Act Amendments of 1986, however, prohibits the use of lead-
containing solder to bond pipes for plumbing in public potable water systems
if the solder contains more than 0.2 percent lead (42 U.S.C. 300f). States
were required to enforce this law as of June 19, 1988. The substitute solders
that dominate the plumbing solder market are 95 tin/5 antimony solder alloy,
and silver-containing solder (2 to 3 percent silver) for use on ferrous base
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metals (PDI 1989, NAPHCC 1989). It is important to note, however, that the
majority of plumbing solder would not be expected to be disposed of in MSW.
2. Consumption of Cadmium in Solder
While cadmium occasionally may be used in specialty solders, it is
a toxic compound that can emit poisonous fumes during the soldering process
and is, therefore, not used in consumer applications disposed at MSW. The use
of solders containing cadmium demands a controlled process under a hood
(Keeler 1987). Although light bulbs were once manufactured with a cadmium-
containing solder, virtually all bulbs are currently manufactured with
tin/lead solder (Sylvania 1989a). Cans and consumer electronics also do not
contain cadmium solder (NFPA 1989a, IPC 1989c).
D. Potential Substitutes for Lead- and Cadmium-containing Solders
Potential substitutes for lead-containing solders may be broken into two
groups -- substitute solders and substitute processes. Depending on the
soldering process used, some alternative solders may be used as drop-in
substitutes, and others may require redesign of soldering equipment or other
processing equipment. Substitute processes usually eliminate the use of lead-
containing solder by eliminating the need for solder during manufacturing.
For example, can manufacturers may eliminate solder use by substituting a
welding process that requires no solder. The availability and cost of
potential substitutes for each of the market areas identified is discussed in
the remainder of this section. Consumer electronics manufacturers will
continue to use lead-based solders, as will manufacturers of light bulbs.
Lead-containing solders used in can manufacturing have for the most part been
eliminated through the use of substitute processes (CMI 1989a). Because the
use of cadmium in consumer electronics, cans, and light bulbs is rare,
substitutes for cadmium-containing solders are not discussed.
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! Substitutes for Lead-containing Solder in Consumer Electronics
Although many types of solder may substitute for tin/lead solder
used in the manufacture of printed circuit boards in consumer electronics,
none of the substitutes have exactly the same characteristics as tin/lead
solder. The use of a substitute solder usually changes the soldering
characteristics of melting temperature, required flux type, ability to wet the
surfaces to be soldered, and bond strength. Depending on the substitute
solder and the particular application for which it is used, the soldering
characteristics may be enhanced or diminished. The advantages and
disadvantages of the common specialty alloy families are presented in Table
27.
The trend of the printed circuit board industry toward surface mounted
components will probably increase the use of indium and bismuth alloys due to
their low melting point and superior thermal fatigue resistance to slow-cycle
fatigue. These qualities are important for manufacturing surface mounted
circuit boards because of the stresses induced by the small size of the bonds
and the large coefficients of thermal expansion (Manko 1988, Keeler 1987).
Other alloy families may also be used for soldering surface mounted
components. The choice of solder depends primarily on the material
compatibility with components, melting temperature, strength, and cost (IPC
1989c, Alpha Metals 1989). Because the variety of custom compositions is
extensive, it is not possible to describe the soldering characteristics of all
alternative solders. Instead, some of the most important general attributes
of each alternative solder family are discussed below.
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Table 27. Advantages and Disadvantages of Potential
Substitute Solders for Consumer Electronic Applications
Solder Alloy Family
Advantages
Disadvantages
Bismuth/Tin
Tin/Silver
Indium/Tin
Indium/Silver
Well-suited to the
new surface mount
assembly technology
Can be used to
solder silver-
plated base metal
without
significantly
solubilizing the
silver
Well suited to the
new surface mount
assembly technology
Compatible with
gold and other
precious metals
Well suited to the
new surface mount
assembly technology
Compatible with
gold and other
precious metals
May have
unacceptably low
melting
temperatures for
use in consumer
electronics
applications
Higher cost than
tin/lead solder
Less ductile than
indium and bismuth
solder alloys
Higher cost than
tin/lead solder
Low melting point
may not be suitable
for high
temperature
applications
As much as 20 times
the cost of
tin/lead solder
Low melting point
may be not suitable
for high
temperature
applications
As much as 20 times
the cost of
tin/lead solder
Sources: ADL 1990, IPC 1989c, Manko 1979, Keeler 1987, Indium 1989e.
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a. Indium Alloys
Indium alloys are one of the most important potential
substitutes for tin/lead solder used in printed circuit board manufacturing.
Unlike tin, indium is compatible with gold and other precious metals (Keeler
1987). Most indium alloy solder is used to solder gold or gold-plated parts
(Indium 1989b). Also, indium alloys do not require radically different
soldering temperatures; in comparison to the tin/lead alloy family, many
indium alloys melt at a lower or equivalent temperature (see Figure 2).
The low melting temperature of indium alloys not only reduces thermal
shock to electrical components, it also imparts ductility to a solder joint so
it will not crack (Keeler 1987). Mismatched coefficients of expansion between
the circuit board and the electrical components can create serious stress
problems (especially with surface mount technology) (Manko 1986). The
ductility of indium solders not only relieves this thermal stress, it also
helps the solder bonds to withstand excessive vibration (Keeler 1987). On the
other hand, the high operating temperature of many consumer products combined
with this low melting temperature may make indium solder unsuitable for some
applications (ADL 1990).
b. Bismuth Alloys
Bismuth alloys melt from 300"F down to 100*F -- well below
the boiling point of water (Manko 1979). Extremely low temperature solders
are not used in consumer electronics because such products may endure high
heat levels during use (Kapp 1989, Indium 1989e). Bismuth alloys with
relatively high melting temperatures, however, can be used with success (Manko
1979, IPC 1989c). Because all bismuth alloys melt at a relatively low
temperature compared to other soldering alloys (see Figure 2), bismuth solder
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9S CADMIUM
5 SILVER
LEAD- I
SILVER I
ALLOYS!
Hard
Solder
CADMIUM-ZINC ALLOYS
INDIUM-
BASE
ALLOYS
BISMUTH-
BASE
ALLOYS
Soft
Solder
Figure 2. Melting Temperatures of Common Soldering Alloys (*F)
(Adapted from Menko 1979.)
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can be used to rework or repair solder joints without melting surrounding
solder bonds. Bismuth also tends to improve the wetting ability of solder
(Manko 1979).
c. Tin/Silver Allovs
Because tin/lead solder can easily dissolve silver off a
part during soldering due to the solubility of silver in tin, alternative
solder alloys are useful for soldering silver-plated electrical contacts.
While the use of alloys containing little tin seems to be a logical solution,
such alloys generally melt at high temperatures and have poor wetting
characteristics. Because the solubility of silver in tin increases with an
increase in temperature, one might try a low melting alloy. With the
exception of the very low temperature bismuth alloys, however, most low
temperature solder alloys are rich in tin. Therefore, the most satisfactory
solution to soldering silver-plated parts is to use solder that already
contains silver to decrease the solubility of the silver plating in the tin
component of the solder. Tin/silver alloys are a good alternative for
soldering silver-plated electrical contacts. This type of alloy generally
contains little silver due to the expense of silver (Manko 1979).
d. Other Considerations
The soldering method used has a bearing on the type of alloy
a manufacturer can use. Wave soldering machines must use eutectic or near-
eutectic solders (Berke 1989a). Most wave soldering machines can be adjusted
to use substitute solders of eutectic or near-eutectic composition. The
majority of printed circuit boards manufactured today are wave soldered
(Indium 1989d).
An increasing number of circuit boards employ surface mount technology.
In this process, printed circuit boards are manufactured through the use of a
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reflow soldering process. This process requires solder paste/cream (lead-
containing or non-lead-containing solders can be employed) that does not need
to be a eutectic composition. Approximately 30 percent of the printed circuit
boards manufactured today employ surface mount assembly technology (IPC
1989c).
The suitability of a soldering alloy for a particular application must
be determined on a case-by-case basis. Although history of other applications
»
can be used as a guideline, there are no scientific rules to predetermine the
wetting ability of solder on the materials to be soldered (Manko 1979).
e. Cost of Substitute Solders
The main determinant of solder cost is the cost of the
metals that compose the solder. The cost of the metals used in the consumer-
electronics substitute solder alloy families listed in Table 27 are as
follows:
indium $180/lb.
silver $89/lb.
bismuth $6.40/lb.
tin $4.10/lb.
Even a small difference in price between solders can have a large impact on
the consumer when a large purchase is made (Indium 1989e). The cost for the
metals used in the eutectic compositions of the solder alloy families listed
in Table 27 are as follows:
52 indium/48 tin $96.05/lb.
97 indium/3 silver $177.28/lb.
58 bismuth/42 tin $5.85/lb.
96.5 tin/3.5 silver $8.04/lb.
Because of the expense of indium solders, they are not commonly used (Indium
1989e). The main reason for the use of indium solder is to bond precious
metal contacts such as gold (unlike tin, indium will not solubilize precious
metals) (Indium 1989b). Bismuth/tin and tin/silver alloys are commonly used
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for electronics, but many variations in the component metals and their
compositions may be used to solder consumer electronics depending on the
particular application. The solder compositions discussed here should serve
only as an initial guide to determining suitable substitutes for lead-
containing solder used in consumer electronics.
While solder prices depend primarily on the cost of the constituent
metals, the solder form* also has a bearing on cost. Simple solder forms,
such as ingots, are relatively cheap to produce compared to specialized forms
such as solder tubing. The manufacturing cost for ingots is approximately
$4.00 per pound (Federated 1989b). Because the ease that a solder may be
formed depends on its composition, the price of different types of solder is
not proportional across the range of available forms (Indium 1989c). In
general, however, the cost of bismuth/tin and tin/silver alloys is
approximately the same as the cost of tin/lead alloys, while indium alloys
cost up to 20 times as much as tin/lead alloys (Talco 1989, Indium 1989e).
Eutectic tin/lead alloy (the commonly used composition of 63 percent tin and
37 percent lead) costs $3.75 per pound in ingot form (Talco 1989).
2. Potential Substitutes for Lead-containing Solder in Cans
Soldering is a metallurgical bonding process in which metallic
continuity from one metal to another is established. Brazing and welding, two
other common metallurgical joining processes, can also create metallic
continuity between metals. Although these substitute processes are not
appropriate joining methods for the printed circuit board applications where
the majority of solder is used, welding is commonly used in the manufacture of
cans (CMI 1989a). The crimping and drawing process also accounts for a large
Some common solder forms are wire, paste, and ingot.
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portion of can manufacturing. The common substitutes used to eliminate
tin/lead solder in cans (see Table 28) are discussed below.
a. Welding and Brazing
Welding is defined as a metallurgical joining process that
relies on the diffusion of the base metals with or without filler metal for
joint formation (Manko 1979). Welding is the most commonly used substitute
process for soldering (NFPA 1989c).
The welding process requires the use of copper electrodes to produce
smooth seams with no impurities. Both the welding and soldering processes are
used to produce three piece cans (CMI 1989a).
b. Drawing and Crimping
As explained previously in this chapter, cans may be
categorized as two piece or three piece cans. Virtually all beverage cans are
now two piece cans, although beverages were packaged in soldered three piece
cans in the past (CMI 1989a).
The technology used to produce all two piece cans is drawing and
crimping. This process entails drawing sheet metal into a cup shape, and then
attaching a metal lid on top of the cup by squeezing a folded seam between the
cup and lid. Beverage cans constitute the majority of cans produced in the
U.S. (CMI 1989a, 1989b).
c. Substitute Solders
Some food and non-food products are still produced in
solder-containing three piece cans, but almost no solder used in domestic can
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Table 28.
Advantages and Disadvantages of Substitute Processes
and Solders for Consumer Can Applications
Process or Solder
Advantages
Disadvantages
Crimping
Welding
Tin Solder
Eliminates the need
for solder
Eliminates the need
for solder
Eliminates the
possibility of lead
leaching into
canned food
products*
May be used in non-
food cans
None identified
None identified
Tin solder is more
expensive than
tin/lead solder
Note: The costs associated with crimping and welding of cans are comparable to
the costs associated with soldering.
Domestic soldered food cans for dried food such as coffee may contain lead
in the solder. Dried food, however, does not leach the solder into the food
product. Some imported food cans for foods packed in juice (such as
grapefruit sections) may employ lead-containing solder.
Sources: Karmal 1989a, 1989b; Elkins 1989b.
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manufacturing contains lead (NFPA 1989b, CMI 1989b).* Some dry food products
such as coffee may still be packaged in cans soldered with relatively cheap
lead solder because there is no danger of lead leaching into the food product.
Imported food cans also may contain lead solder. The substitute solder used
by domestic manufacturers is plain tin solder (NFPA 1989b). The quality of
the joints produced with tin solder is equal to those produced with tin/lead
solder, but pure tin solder is more expensive than tin/lead solder (NFPA
1989b).
3. Potential Substitutes for Lead-containing Solder in Light
Bulbs
Lead/tin solder is used in light bulb manufacturing because it is
low cost, works fast, and bonds materials aggressively. Some substitute
materials, however, are available (see Table 29).
Relatively expensive indium solder could be used instead of lead/tin
solder, but it tends to oxidize easily during the light bulb soldering
process. (The final step is to heat the solder with torch flame so that the
solder will spread over the base of the bulb.) Oxidation of indium solder
could be prevented by flowing nitrogen over the molten solder (to displace the
oxygen in the air) or by soldering in a vacuum. Both measures will increase
the cost of the soldering process. Tin/zinc solder could also be used, but it
needs to be tested for this application (Sylvania 1989a). Tin/zinc solder
does not flow as well as tin/lead solder (Kapp 1989).
* Approximately 3 percent of food cans for dried food contain lead alloy
solders. No beverage cans contain lead alloy solders. Although data is not
available for general packaging cans, this type of can represented only 5
percent of total can manufacturing in 1988 (food and beverage cans represented
95 percent) (CMI 1989a).
75
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Table 29. Advantages and Disadvantages of Potential
Substitute Solders for Light Bulb Applications
Substitute Solder Advantages ' Disadvantages
Indium-Based Solder Does not contain More expensive than
lead tin/lead solder
Oxidizes when used
in the light bulb
manufacturing
process
Tin/Zinc Does not contain Does not flow as
lead well as tin/lead
solder
Sources: Sylvania 1989a, 1989b; Kapp 1989.
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4. Future Trends and Developments
Conductive adhesives are a potential future substitute for
tin/lead solder used in electrical applications such as consumer electronics
and light bulbs. The use of conductive adhesives would eliminate the need for
fluxing and post-soldering flux cleaning (Locktite 1989b). However, several
problems currently prohibit the widespread use of conductive adhesives.
Most conductive adhesives are silver-filled to achieve the desired level
of conductivity. Even though conductive adhesives usually consist of more
than 50 percent silver (compared to only a few percent silver contained in
tin/silver solder), they still do not conduct as well as solders (Locktite
1989a, 1989b). Furthermore, the high silver content means the price of
conductive adhesives is high relative to solders (Locktite 1989b). The high*
cost may be somewhat mitigated by the elimination of flux and flux cleaning
costs.
Conductive adhesives are currently used in some instances where the
surface of a part may not be conductive to solder bonding or where solder may
be too brittle for the application (Locktite 1989b). The wholesale
replacement of tin/lead solder with conductive adhesives, however, is not
currently considered a realistic option (IPC 1989c).
Some research is also being done on conductive polymers. This potential
substitute is in early development stages and little information is available
regarding performance (Locktite 1989b).
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E. References
ADL. 1990 (November 15) Lead Use and Substitutes. Report to Lead Industries
Association. Prepared by Arthur D. Little, Inc., Cambridge, MA.
Arconium. Undated. Arconium, 400 Harris Avenue, Providence, RI. "Arconium
Specialty Alloys."
Arconium. 1989 (July 24). J. Hamilton, Sales Representative. Providence,
RI. Transcribed telephone conversation with Thomas Hok, ICF Incorporated,
Fairfax, VA.
Alpha Metals. 1989 (July 14). S. Arora. Senior Chemist. Jersey City, NJ.
Transcribed telephone conversation with Thomas Hok, ICF Incorporated, Fairfax,
VA.
Bannos, T.S. 1988 (October). "Lead-Free Solder to Meet New Safe Drinking
Water Regulations." Welding Journal. Vol. 67, pp. 23-26.
Belser, R.B. 1954. "Indium -- A Versatile Solder to Metals and Non-metals,"
found in Intermediate Indallov Solders, published by the Indium Corporation of
America, Utica, NY.
CMI. 1989a (June 1). Can Manufacturers Institute. D. Karmal, Counsel.
Washington, DC. Transcribed telephone conversation with Thomas R. Hok, ICF
Incorporated, Fairfax, VA.
CMI. 1989b (July 28). Can Manufacturers Institute. D. Karmal, Counsel.
Washington, DC. Transcribed telephone conversation with Thomas R. Hok, ICF
Incorporated, Fairfax, VA.
EPA. 1989 (January). U.S. Environmental Protection Agency. Characteristics
of Products Containing Lead and Cadmium in Municipal Solid Waste Facilities
1970 to 2000. Prepared by Franklin Associates, LTD. Prairie Village, KS.
Federated-Fry Metals. 1989a (July 20). W. Hockenberry. Sales. Altoona, PA.
Transcribed telephone conversation with Thomas Hok, ICF Incorporated, Fairfax,
VA.
Federated-Fry Metals. 1989b (August 15). W. Hockenberry. Sales. Altoona,
PA. Transcribed telephone conversation with Thomas Hok, ICF Incorporated,
Fairfax, VA.
FPMSA. 1989 (July 28). Food Processing Machinery and Supplies Association.
L. Herbert. Executive Vice President. Alexandria, VA. Transcribed telephone
conversation with Thomas Hok, ICF Incorporated, Fairfax, VA.
Hollis Automation. 1989a (July 18). E. Berke. Marketing Services
Supervisor. Nashua, NH. Transcribed telephone conversation with Thomas R.
Hok, ICF Incorporated, Fairfax, VA.
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Hollis Automation. 1989b (July 28). E. Berke. Marketing Services
Supervisor. Nashua, NH. Transcribed telephone conversation with Thomas R.
Hok, ICF Incorporated, Fairfax, VA.
Indium Corporation of America. 1988. Indium Corporation of America, 1676
Lincoln Avenue, Utica, NY. "Indalloy* Specialty Solders & Alloys."
Indium Corporation of America. 1989a (July 19). M. DeMarco, Sales
Representative, Utica, NY. Transcribed telephone conversation with Thomas
Hok, ICF Incorporated, Fairfax, VA.
Indium Corporation of America. 1989b (July 19). R. Altieri. Applications and
Engineering. Utica, NY. Transcribed telephone conversation with Thomas Hok,
ICF Incorporated, Fairfax, VA.
Indium Corporation of America. 1989c (July 20). M. DeMarco, Sales
Representative, Utica, NY. Transcribed telephone conversation with Thomas
Hok, ICF Incorporated, Fairfax, VA.
Indium Corporation of America. 1989d (July 28). R. Altieri. Applications
and Engineering. Utica, NY. Transcribed telephone conversation with Thomas
Hok, ICF Incorporated, Fairfax, VA.
Indium Corporation of America. 1989e (August 15). J. Ferriter. Application*
and Engineering. Utica, NY. Transcribed telephone conversation with Thomas
Hok, ICF Incorporated, Fairfax, VA.
IPC. 1989a (May 31). Institute of Printed Circuits. D. Bergman. Chicago/
IL. Transcribed telephone conversation with Thomas Hok, ICF Incorporated,
Fairfax, VA.
IPC. 1989b (July 20). Institute of Printed Circuits. D. Bergman. Chicago,
IL. Transcribed telephone conversation with Thomas Hok, ICF Incorporated,
Fairfax, VA.
IPC. 1989c (July 28). Institute of Printed Circuits. D. Bergman. Chicago,
IL. Transcribed telephone conversation with Thomas Hok, ICF Incorporated,
Fairfax, VA.
Kapp Alloy and Wire, Inc. 1989 (July 19). D. Porter, Technical Director.
Altoona, PA. Transcribed telephone conversation with Thomas Hok, ICF
Incorporated, Fairfax, VA.
Keeler, R. 1987 (July). "Specialty Solders Outshine Tin/Lead in Problem
Areas." Electronic Packaging and Production, pp. 45-47.
Locktite Corporation. 1989a (May 31). R. Thompson. Newington, CT.
Transcribed telephone conversation with Thomas Hok, ICF Incorporated, Fairfax,
VA.
Locktite Corporation. 1989a (July 28). J. Jesowski. Commercial Development
Specialist, Newington, CT. Transcribed telephone conversation Thomas Hok, ICF
Incorporated, Fairfax, VA.
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Manko, H.H. 1979. Solders and Soldering. Published by McGraw-Hill Book
Company, New York, NY. Second edition.
Manko, H.H. 1986. Soldering Handbook for Printed Circuits and Surface
Mounting. Published by Van Nostrand Reinhold Company, New York, NY.
Mullen, J. 1984. "How to Use Surface Mount Technology." Texas Instruments
Publishing Center, Dallas, TX.
NAPHCC. 1989 (August 10). National Association of Plumbing-Heating-Cooling
Contractors, R. Warren, Technical Director. Falls Church, VA. Transcribed
telephone conversation with Thomas Hok, ICF Incorporated, Fairfax, VA.
NFPA. 1989a (June 1). National Food Processors Association. E. Elkins.
Washington, DC. Transcribed telephone conversation with Thomas Hok, ICF
Incorporated, Fairfax, VA.
NFPA. 1989b (July 31). National Food Processors Association. E. Elkins.
Washington, DC. Transcribed telephone conversation with Thomas Hok, ICF
Incorporated, Fairfax, VA.
NFPA. 1989c (August 15). National Food Processors Association. E. Elkins.
Washington, DC. Transcribed telephone conversation with Thomas Hok, ICF
Incorporated, Fairfax, VA.
PDI. 1989 (August 10). Plumbing and Drainage Institute. S. Baker, Executive
Secretary. Indianapolis, IN. Transcribed telephone conversation with Thomas
Hok, ICF Incorporated, Fairfax, VA.
Sylvania and Laxman, Limited. 1989a (July 18). R. Marlor, Manager, Glass and
Ceramics. Salem, MA. Transcribed telephone conversation with Thomas Hok, ICF
Incorporated, Fairfax, VA.
Sylvania and Laxman, Limited. 1989b (July 28). R. Marlor, Manager, Glass and
Ceramics. Salem, MA. Transcribed telephone conversation with Thomas Hok, ICF
Incorporated, Fairfax, VA.
Sylvania and Laxman, Limited. 1989c (August 30). W. Roach. Engineer,
Fluorescent Bulb Plant. Danvers, MA. Transcribed telephone conversation with
Louis Gardner, ICF Incorporated, Fairfax, VA.
Talco Metals. 1989 (July 18). C. Carabello, Sales Representative.
Philadelphia, PA. Transcribed telephone conversation with Thomas R. Hok, ICF
Incorporated, Fairfax, VA.
Warwick, M.E. 1985 (Spring). "The Wetting and Mechanical Properties of Lead-
free Capillary Plumbing Solders." Brazing and Soldering. No. 8.
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V. LEAD-ACID BATTERIES
Lead-acid batteries are currently the most commonly used type of
rechargeable battery. These batteries are used for starting, ignition, and
lighting in virtually all motorized vehicles, and are used in other
applications where rechargeable portable power is desired (e.g., consumer
electronics such as power tools). The drawback of lead-acid batteries is the
emission of lead and sulfuric acid when these batteries are disposed. Lead-
acid batteries continue to be widely used because based on performance, cost,
and toxicity of potential alternatives, there are currently no acceptable
substitutes. The discussion presented below outlines the disadvantages of the
potential substitutes that have been considered*.
Nickel-zinc batteries have a lower power density** than lead-acid
batteries, a limited lifetime (50 to 200 recharging cycles), and relatively
poor reliability. Nickel-zinc batteries are two to three times the cost of an
equivalent sized lead-acid battery (Palmer 1988).
The power density of nickel-iron batteries is only one fourth to one
third that of lead-acid batteries, and they have very poor low temperature
performance and charge retention (Palmer 1988).
Silver-zinc batteries are very expensive -- 20 to 100 times the cost of
an equivalent sized lead-acid battery. These batteries also have a limited
* Nickel-cadmium batteries are not considered as substitutes because of
the scope of this study but even they do not match lead-acid batteries in
performance. Nickel cadmium batteries are five to ten times the cost of an
equivalent sized lead-acid battery. The power density of nickel-batteries is
20 to 30 percent lower than lead-acid batteries so that the cost of delivered
power per unit cost is 6.67 to 13.33 times more expensive, assuming equal
service lives (Palmer 1988).
** The power density of a battery is the amount of power the battery can
produce relative to its weight.
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lifetime (approximately 250 cycles) and decreased performance at low
temperatures (Palmer 1988).
Even future advance secondary battery systems are not promising. Zinc-
chlorine batteries involve the danger of chlorine leakage and require complex
plumbing and refrigeration. Zinc-bromine batteries present safety problems
when used for automobile ignition applications, and are also bulky. Aqueous
redox flow cells are only being considered for power storage or standby power,
while conductive polymer batteries have low power density and very poor
performance at temperature extremes. Secondary metal-air batteries have low
energy density and may be unstable. Finally, lithium metal-sulfide and
sodium-sulfur high temperature systems require a high operating temperature
and are not suited for power cranking (Palmer 1988).
Reference
Palmer, J.G. 1988 (September). Executive Vice President, Pacific-Dunlop-GNB,
Incorporated, St. Paul, MN. "A Cleaner Environment: Removing the Barriers to
Lead-Acid Battery Recycling." Written in collaboration with M.L. Sappington,
P.E., President, Lake Engineering, Incorporated, Atlanta, GA.
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VI. NICKEL-CADMIUM BATTERIES
A. Overview of the Battery Industry
Secondary (rechargeable) battery systems are based primarily on the same
chemical principles used in the construction of primary (one charge)
batteries. The latter are sometimes called "fuel" cells, because the active
chemicals are consumed in an irreversible reaction. Both types of cells are
based on the difference in electrochemical potential between the anode and
cathode of the cell, which are generally metal plates. This potential is the
driving force that provides the energy to force electrons through the load.
When the difference in potential between the anode and cathode is reduced
sufficiently, there is insufficient energy to overcome the resistance of the
load, and the battery ceases to function. With primary cells, the battery
must be discarded at this point, because the electrochemical reaction cannot
be reversed sufficiently to derive a reasonable performance after charging
(Kirk-Othmer 1978).
The main difference between a primary and secondary cell is in the
nature of the active substances; a secondary battery may be recharged because
it is based on a highly reversible reaction. This allows the battery to be
discharged and then recharged multiple times. A discharge and charge bring
the battery back to its original state, and this pair of actions is called a
cycle. The active substances in a primary battery cannot be recharged.
However, even after charging secondary batteries, the materials do not
return exactly to their previous (charged) state, and therefore, a secondary
battery may be put through only a limited number of cycles. Eventually the
battery's efficiency deteriorates (measured by the battery's output during
discharge relative to the energy input during charging) and may drop to an
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unacceptable level, or the battery may fail to charge altogether (Kirk-Othmer
1978, Moli Energy 1989).
The most common type of secondary battery currently in use is the lead-
acid battery, which is used for starting and ignition in virtually all
motorized vehicles. Sealed lead acid batteries are also quite common and are
found in home security and emergency power systems, as well as in consumer
electronics (VCR's, home computers, camcorders), power tools, toys, and other
applications where portable power is desired.
B. Nickel-cadmium Batteries
Another type of secondary battery which finds widespread use in consumer
applications is the rechargeable nickel-cadmium (Ni-Cd) battery. It is found
in many of the same applications as the sealed lead-acid battery and may be
used in many applications for which the lead-acid is too large. In addition,
Ni-Cd batteries are also frequently substituted for primary batteries, in
applications such as personal tape players, where frequent use and high
discharge rates can result in unacceptably high battery costs.
Ni-Cd batteries are often integrated into an appliance or toy with a
dedicated charger. In such cases, the battery often cannot be removed by the
user and cannot be changed except at an authorized service center for the
product. Because Ni-Cd batteries may last for over 1000 cycles in some
instances, the battery may outlast the useful life of the product. Such
applications (cordless hand vacuums, electric shavers, power tools, etc.)
constitute a large segment of the demand for Ni-Cd batteries.
The other major consumer application of nickel-cadmium batteries is as a
substitute for primary batteries such as the common carbon-zinc battery and
the alkaline battery. As mentioned before, Ni-Cd batteries are most cost-
effective in applications which consume large amounts of power, such as
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portable stereos and photographic strobes, rather than for applications such
as electric quartz clocks, which generally require only a single alkaline cell
each year.
As the popularity of laptop computers, portable video equipment,
cellular phones, and other portable electronic devices increases, the demand
for rechargeable power sources also will increase. Given Ni-Cd batteries'
long cycle life (on the order of 1000 charge-discharge cycles versus 200 for
sealed lead acid batteries), moderately high charge capacity,* availability
in many popular sizes, low cost (roughly ten times the cost of carbon-zinc
batteries, but with more than 100 times the lifetime of carbon-zinc
batteries), and resistance to abuse (overcharge and deep discharge) make them
ideal for consumer applications.
The only drawback to Ni-Cd cells is concern about the toxicity of the
cadmium in the batteries, which eventually ends up in the waste stream.
Sealed lead-acid batteries, although currently commonly available, would not
be an acceptable alternative, because of similar concerns over lead in the
waste stream. Fortunately however, there are other battery systems which,
although currently not suitable for consumer applications, may eventually be
developed sufficiently for such uses. These battery systems are discussed
below in Section D.
C. Consumption of Cadmium in Nickel-cadmium Batteries
The amount of cadmium discarded in Ni-Cd batteries is presented in Table
30. As the table indicates, there has been an increase in total cadmium
discards by a factor of 18 in the period 1970 to 1986. This is due in
* Charge capacity is defined as the maximum charge that a battery will
hold. The charge capacity decreases as the number of cycles through which the
battery has passed increases (Moli Energy 1989).
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Table 30. Discards of Cadmium in Nickel-cadmium Batteries in MSW
Cadmium in Discards of Cadmium in Discards of Total Cadmium
Batteries in First Year" Batteries in Fourth Yearb Discarded
Year (tons) (tons) (tons)
1970
1975
1980
1986
17
33
79
127
34
176
917
800
51
209
996
927
Approximately half of all loose Ni-Cd batteries (20 percent of all Ni-Cd
Batteries are loose) are assumed to be discarded the same year by the
consumer.
b The remaining loose batteries and all batteries sealed within products
(appliances, toys, etc.) are assumed to be discarded after four years.
These constitute 90 percent of all Ni-Cd batteries.
Source: EPA 1989.
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large part to the increase in demand for the use of Ni-Cd batteries in
portable consumer electronic equipment and in rechargeable throw-away devices
such as toys, hand-held power-vacuums, and other such items.
D. Potential Substitutes for Nickel-cadmium Batteries
There are a wide range of potential substitutes for nickel-cadmium
batteries, including:
lithium secondary batteries;
silver-zinc batteries;
nickel-zinc batteries;
nickel-hydrogen batteries; and
primary batteries.
With the exception of primary batteries, however, none of these potential
substitutes has seen much, if any, commercial use in consumer products because
of technical complications, reduced service life, and high cost.
1. Lithium Secondary Batteries
One of the more promising technologies is the rechargeable lithium
cell, which is already used to a very limited extent in some consumer
applications. Lithium cells are manufactured with a variety of materials, and
include lithium-air batteries that allow air to circulate freely in the cell.
According to one supplier, rechargeable lithium batteries have greater charge
capacity than Ni-Cd batteries of a comparable size (SAFT 1989a). There are
currently many limitations, however, to their use. Lithium batteries are
currently much more expensive (at least twice the cost) of Ni-Cd batteries.
Their cycle life is only 200-400 cycles, versus 1000 or more for Ni-Cd
batteries, and in addition, they are less tolerant to abuse. Finally, large
cells are not yet available, although there is work currently being funded to
investigate and produce lithium cells for military applications such as
communications equipment (Yardney 1989b). Although lithium cells cannot be
used to power electric cars (normally powered by lead-acid batteries), there
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is a possibility that lithium cells could be used for this application in the
future (SAFT 1989c).
It is simple enough to add circuitry to the recharging equipment to
prevent overcharge, although it would further increase the cost of using
lithium batteries. Circuitry to prevent a deep discharge also is required in
the equipment in which the batteries are used, which precludes their use in
many applications in which Ni-Cds are currently found, and may make the cost
of any product extremely high (SAFT 1989a). Because of these limitations, it
is likely that lithium rechargeable batteries will be found only in
applications where the higher cost of the batteries and controlling circuitry
are not an obstacle, such as in computers. In such applications, the cost of
the battery system and controlling circuitry is not large relative to the
overall cost of the product (Yardney 1989b).
Advantages of lithium rechargeable batteries include their light weight,
ability to provide energy in freezing temperatures, and very high efficiency
(Chemical Business 1989, SAFT 1989c). Possible applications for lithium
batteries include portable cellular phones, lap-top computers, portable
radios, and military applications (Moli Energy 1989).
2. Silver-zinc Batteries
Another battery technology currently in use is the silver-zinc
system, which is used primarily (90X of the time) for military and space
application* and has a high energy density (Kirk-Othmer 1978, SAFT 1989c).
However, there are many limitations which may restrict its use in consumer
applications such as the high cost of such batteries. According to one
supplier, silver-zinc batteries cost about five times more than similar
nickel-cadmium batteries (Yardney 1989a). This high cost is due in part to
the cost of the silver, a precious metal. Because of the value of silver,
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expended batteries would probably be recycled to recover the metal. Recycling
could allow for some recovery of the initial cost of purchase (Yardney 1989a).
Another obstacle to widespread use of silver-zinc batteries is their
rather limited service life; silver-zinc batteries typically last 100-200
cycles and have about a 2-year wet life (the wet life is the amount of time it
takes for the cell to degrade without cycling). Because of these limitations,
it is highly unlikely that silver-zinc batteries could ever succeed as a
substitute for the Ni-Cd system except in the very short term and for
applications where cost is no object (Yardney 1989b).
3. Nickel-zinc Batteries
One battery system which generated a good deal of interest during
the early and mid-1970s was the nickel-zinc cell. It potentially offers a
charge density greater than that available from nickel-cadmium batteries but
at a lower cost than silver-zinc. Some research into improving the
performance of nickel-zinc batteries was funded by the U.S. government for use
in electric vehicles. According to one company involved in that development
effort, interest in electric vehicles waned; although attempts were made to
continue the study, the funds were no longer available and the research was
essentially stopped (Yardney 1989a). Although these previous studies focused
on large batteries such as might be found in electric vehicles, future
development might focus on smaller cells if such a demand arose.
A primary advantage of a nickel-zinc system over the silver-zinc battery
is the cost. Although its performance is not as high as its silver-based
counterpart, it is also not subject to the wide fluctuations in price
resulting from speculation in markets for precious metals such as silver. In
spite of this, the price is currently quite high due to the developmental
nature of the Ni-Zn batteries produced thus far. Although nickel-zinc
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batteries may be recycled, the metal recovery may not by worth the cost (SAFT
1989c). However, even if the cost of new cells is brought down, a major
limitation in nickel-zinc cells is their short life. Capacity of the battery
drops rapidly with multiple cycles. The cell can be periodically
"conditioned" by fully discharging the zinc electrode, which restores some of
the original capacity. After about 100 cycles, however, the cell can only
reach about two-thirds of its original capacity, even after conditioning. Due
to its initially higher charge density (relative to a nickel-cadmium cell),
such a loss of capacity still might provide acceptable performance if the cell
is conservatively rated. Further research in this area may alleviate some of
these limitations and reduce production costs (Yardney 1989b).
4. Nickel-hydrogen Batteries
Another high technology battery system which currently is found "
only in very exotic applications is the nickel-hydrogen cell. Its gravimetric
charge density* is slightly higher than that of a nickel-cadmium cell and the
service life is somewhat longer (Kirk-Othmer 1978). The cycle life of the
cell is also about double (1,500-2,000 cycles) that of a Ni-Cd system (Yardney
1989a). For these reasons, nickel-hydrogen cells were originally developed
for satellite applications, where this combination of characteristics is
advantageous. However, the hydrogen in the cell is in the gaseous form, and
the operating pressure is much higher, ranging from 3-20 times atmospheric
pressure, as compared to 0-3 atmospheres for a Ni-Cd cell. Because of these
high operating pressures, construction is labor-intensive and very expensive.
Unless significant breakthroughs are made in reducing the cost of
The gravimetric charge density is the charge density per unit of
weight, as opposed to unit of volume.
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construction, the nickel-hydrogen system is likely to be found only in very
specialized applications (Yardney 1989a).
5. Primary Batteries
Primary batteries are available in a variety of configurations.
The common carbon-zinc battery' has been replaced by the alkaline battery as
the dominant commercially available primary cell (Chemical Business 1989).
Other types of primary batteries include lithium batteries and mercury
batteries (Panasonic undated).
Primary lithium batteries last up to five times as long as carbon-zinc
batteries (Chemical Business 1989). They have a very long life and are often
used in watches and cameras. Primary mercury batteries have a compact size,
long shelf life, and excellent voltage stability. Mercury batteries are often
used in watches, calculators, cameras, and hearing aids (Panasonic undated).
While primary batteries do not contain cadmium, constant replacement may
be expensive in applications involving high discharge rates.
E. Limitations on Substitution
The alternative secondary battery systems listed all have significant
limitations when compared to the Ni-Cd system. In addition, many of these
technologies are currently in an embryonic stage of development and their
costs are quite high. As experimentation and development proceeds, the
limitations as well as the costs of these potential substitute products may be
reduced.
In general, nickel-cadmium batteries have performance characteristics
which make them difficult to replace in consumer applications. These are as
follows:
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A long cycle life that allows Ni-Cd batteries to be
installed in products where the batteries are not readily
accessible to the consumer. A cordless product can then be
made that requires little attention on the part of the user.
The charge density is comparable to that of many primary
cells. The higher capacity of these products is an
advantage in some applications.
Ni-Cd batteries are relatively forgiving of misuse. Slight
overcharging does not seriously damage their performance,
and deep discharge is acceptable except when several
batteries are arranged in series.
Ni-Cd batteries cost significantly less than other
rechargeable batteries currently available, with the
exception of lead-acid systems which are not considered to
be substitutes due to the scope of this report.
Some of the alternative battery technologies discussed in this chapter
offer the potential for better performance than Ni-Cd batteries in one or more
aspects (see Table 31). Unfortunately, cost information on possible
substitute consumer products is not available at this time because of the
experimental nature of potential substitute technologies. With sufficient
research and development, however, it is not unreasonable to hope that some of
these technologies (particularly lithium and nickel-zinc cells) can be
improved sufficiently to eventually compare with nickel-cadmium batteries.
The solid performance and low cost of nickel-cadmium batteries make it
unlikely that there will be replacements in the near future. In fact,
according to one industry contact (SAFT 1989b), if both Ni-Cd and lead-acid
batteries were eliminated immediately, substitute rechargeable batteries would
not be available in the short run due to cost and performance limitations.
This source expressed the belief, however, that there is enough interest in
rechargeable batteries to develop alternate systems over time.
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Table 31. Advantages and Disadvantages of Substitutes
for Nickel-cadmium Batteries
Substitute Battery
Advantages
Disadvantages
Lithium Battery
Very light weight
Provide energy in
freezing
temperatures
Very efficient
Silver-zinc Battery
Very high energy
density
Nickel-zinc Battery
Relatively high
energy density
Nickel-hydrogen
Battery
Twice the cycle
life of a nickel-
cadmium battery
Primary Battery
(alkaline, lithium,
and carbon-zinc)
Over twice the
cost of nickel-
cadmium batteries
Less than half the
lifetime of a
nickel-cadmium
battery
Sensitive to abuse
(overcharging and
deep discharging)
Five times the
cost of nickel-
cadmium batteries
Less than one-
fifth the lifetime
of a nickel-
cadmium battery
High cost
Less than one-
tenth the lifetime
of a nickel-
cadmium battery
More expensive
than a nickel-
cadmium battery
due to high
atmospheric
pressure required
in the cell
Replacement costs
may be substantial
in high discharge
applications
Sources: Yardney 1989a, 1989b, SAFT 1989a, Chemical Business 1989.
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F. References
Chemical Business. 1989 (July/August). "The Assault on Batteries," p. 35-36.
Kirk-Othmer. 1978. Encyclopedia of Chemical Technology. John Wiley and Sens
Publishing Co., Inc. Vol. 3, pp. 569-639.
Moli Energy. 1989 (January). Product literature on Molicel Lithium
batteries.
EPA. 1989 (January). U.S. Environmental Protection Agency. Characterization
of Products Containing Lead and Cadmium in Municipal Solid Waste Facilities
1970 to 2000. Prepared by Franklin Associates Ltd., Prairie Village, KS.
Panasonic. Undated. "Batteries," a publication of Panasonic, Secaucus, NJ.
SAFT America. 1989a (July 14). G. Lupul. Maryland. Transcribed telephone
conversation with Donald Yee, ICF Incorporated, Fairfax, VA.
SAFT America. 1989b (July 17). R. Vikmund. Valdosta, GA. Transcribed
telephone conversation with Donald Yee, ICF Incorporated, Fairfax, VA.
SAFT America. 1989c (August 15). P. Scardaville, Director of Engineering.
Valdosta, GA. Transcribed telephone conversation with Alex Greenwood, ICF
Incorporated, Fairfax, VA.
Yardney Battery. 1989a (July 13). T. Aretakis. Connecticut. Transcribed
telephone conversation with Donald Yee, ICF Incorporated, Fairfax, VA.
Yardney Battery. 1989b (July 20). D. Wissocker. Massachusetts. Transcribed
telephone conversation with Donald Yee, ICF Incorporated, Fairfax, VA.
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VII. GLASS AND CERAMIC PRODUCTS
A. Overview of Glass/Ceramic Products
Glass is an inorganic, brittle, transparent or translucent material that
consists of a mixture of crystalline materials such as silicates, borates, or
phosphates combined by melting at high temperatures and then cooling to a
rigid condition. Silicates are the main constituent in glass. Silica by
itself makes a good glass, but its high melting point (about 1700 C°) and its
high viscosity in the liquid state make it difficult to melt and work.
Glass manufacturing begins by mixing and melting the raw materials, such
as silicates and limestone. After melting, the molten glass, called metal, is
refined, freed of bubbles, and then cooled.. Heat treatment follows, and the
glass is strengthened.
Ceramics are non-metallic materials such as clay, produced by firing at
very high temperatures. Ceramics are usually hard, brittle, and are good
electrical and thermal insulators. Ceramic products are often divided into
two groups:
pottery and brick are shaped or formed before high-temperature
treatment; and
glass and cement are shaped afterward.
Glazes and enamels are also used with glass/ceramic products. Enamel or
porcelain enamel is a decorative or protective glassy coating which is applied
to metal or glass. Glass color enamels are used to decorate and label glass
objects. Glaze is a glassy coating applied on ceramics.
B. Uses of Lead and Cadmium in Glass/Ceramic Products
1. Use of Lead in Glass/Ceramic Products
Lead monoxide often is used as an intermediate or modifier in
glass products. As an intermediate, lead monoxide adds to the brilliance of
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the glass products, and as a modifier, it lowers the melting temperature,
thereby simplifying glass processing. Alkali metal* oxides also are widely
used and are inexpensive, but glass produced with these products may require
modifications in the manufacturing processes when substituted for lead
products and can not fully replace lead in the glass formulation (Nordyke
1984).
Lead-containing glass also can shield high energy radiation and the high
refractive index of lead yields excellent properties for optics and for hand-
formed art ware. The glass and ceramic use areas identified in the EPA 1989
report are discussed in the following section. In addition, Table 32 lists
the special properties that are associated with lead-based glass/ceramic
products and specific glass/ceramic products that require these properties.
a. Television and X-ray Shielding Parts
Leaded glass is used in three main parts of television
picture tubes: in the neck surrounding the electron gun, in the funnel that
provides structural integrity, and in the faceplate or panel used in the
television screen. About 2.25, 22.5, and 28.4 percent lead monoxide is used
in the faceplate, funnel, and neck, respectively. Lead is used because it
absorbs radiation from the electron gun. Linear absorption (or attenuation)
coefficients** that increase as lead oxide content increases and the
thickness of the absorbing material (in this case, leaded glass) are useful
indicators in determining the effectiveness of a compound for absorbing
radiation. To achieve a low dosage rate of radiation, a material with a high
* Alkali metals are metals in Group 1A of the Periodic Table (e.g.,
lithium, sodium, potassium, etc.).
The linear absorption coefficient (u) is computed by multiplying the
mass absorption coefficient of the compound (in this case, lead oxide) by the
density of the absorbing material (Nordyke 1984, Corning 1989d).
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Table 32. Properties Lead Imparts to Glass/Ceramic Products
Properties
Associated Glass/Ceramic Products
Low Melting Range
Wide Softening Range
(Processability)
High Index of Refraction
Resonance
Radiation Absorption
Good Electrical Properties
Enamels
Fluorescent lighting and neon sign
tubing
Optical Glass; Crystalware
Crystalware
Leaded glass in televisions and X-
ray shielding
Glazes and Enamels; Neon sign tubing
Source: Nordyke 1984.
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linear absorption coefficient, large thickness, or combinations of these
factors can be used.
From a design standpoint, the thickness of these television parts tends
to be fixed by the strength requirements of the pieces. The faceplate,
funnel, and neck are 1.14, 0.25, and 0.25 cm thick, respectively (Nordyke
1984). The Joint Electron Device Engineering Council of the Electronics
Industry Association has set the radiation standard at a dose rate of 0.5 mR/h
(milliroentgen per hour) measured 5 cm from the tube face (Nordyke 1984). For
this dose rate and these thicknesses, linear absorption coefficients are
typically 28, 62, and 90, for the faceplate, funnel, and neck, respectively,
As televisions have increased in size, voltage requirements have also
increased resulting in pressure on manufacturers to produce television parts
with higher radiation absorption characteristics (Nordyke 1984).
Manufacturers have typically met this demand by increasing the lead content in
some cases by as much as two-fold.
Leaded X-ray shielding glass is found in areas other then televisions
including hospitals, nuclear power plants, or any other place where radiation
is prevalent; these sources of lead, however, are not expected to contribute
to lead discarded in MSW. Lead content varies from 35 to 82 percent lead
oxide in X-ray shielding glass in these applications.
b- Fluorescent Tubing and Light Bulbs
Lead is used in the outer envelope of fluorescent lighting
and neon sign tubing because of its excellent electrical resistivity
properties (high electrical resistance) and because its low melting
temperature allows easy processability (Nordyke 1984). It is believed that
the lead content in these envelopes is small -- less than 10 percent (Sylvania
and Laxman 1989) while the lead content for neon sign tubing is about 30
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percent lead oxide (Nordyke 1984). Light bulbs contain leaded glass at a
concentration of 20 to 30 percent lead oxide in the flare and exhaust tube,
both of which are part of the mount that is at the base of the bulb (EPA
1989). In addition to providing excellent insulation at the base of the bulb,
lead is also used because of its ease of processability.
c. Optical and Ophthalmic Glass
Optical leaded glass is found in all types of concave and
convex lenses principally because of its high index of refraction.* Optical
glass can be classified into ophthalmic and non-ophthalmic uses. Ophthalmic
glass is used to correct vision deficiencies. About 50 percent of ophthalmic
glass is used in single-vision spectacles which have a moderate refraction
index of 1.523 and use lime glass rather than leaded glass (Nordyke 1984).
The remainder of ophthalmic glass is used in multifocal lenses. Lead oxide
makes up 5 to 10 percent of the segment** used in multi-focal lenses (Corning
1990) and is used to achieve refraction indexes up to 1.7 (Nordyke 1984).
Non-ophthalmic optical glass includes camera and telescopic lenses, and
fiber optics; lead oxide content in these uses ranges from 20 to 30 percent in
cameras and telescopes and from 30 to 40 percent for fiber optics (Schotts
1989). Photochromatic glass or glass that changes color when exposed to light
uses a marginal amount of lead oxide, typically less than three percent
(Corning 1989d).
The index of refraction can be defined as the ratio of the velocity of
light in air to the velocity of light in glass. Generally, as lead content
increases so does the refractive index (Nordyke 1984).
The segment is the point of juncture of two lenses, typically making
up less than 10 percent of the surface area of bifocal lenses (Schotts 1989).
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d. Lead Crystalware
Lead crystal is defined by its lead oxide content but the
term lead crystal is not always applied uniformly. Full lead crystal is
defined as containing at least 32 percent lead oxide, but glassware with lower
percentages of lead oxide, typically about 24 percent, is often sold as lead
crystal (BCR 1990). The use of lead crystal can be traced back to ancient
Russian glasses of the eleventh century. The chemical composition of modern
lead crystalware has not changed appreciably, although improved refractories
and melting furnaces, and purity of raw materials have helped to enhance its
brilliance, smoothness, resonance, and temperature stability properties
(Nordyke 1984).
e. Piezoelectric Ceramics
Combining lead zirconate and lead titanate form the
piezoelectric family of ceramic products known as PZT (lead zirconate
titanate). Piezoelectricity means "pressure electricity" and with ceramics,
PZT can serve as a transducer for electrical and mechanical energy. The use
of PZT is found mainly in small appliances such as watch alarms, automobile
cigarette lighters, and measurement devices where a small mechanical
displacement creates a low voltage. PZT contains about 68 percent lead oxide
(Piezo Kinetics 1989). The family of materials designated PZLT for lead-
lanthanum- zirconate -titanate is commonly used in electrooptic applications
-}
(Nordyke 1984). An electrooptic application such as maintaining memory in a
calculator after turning it on and off is due to the piezoelectric
characteristics of PZLT (Nordyke 1984).
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2. Use of Cadmium in Glass/Ceramic Products
The uses of cadmium in glass and ceramic products are commonly as
a pigment in a glaze, as a colorant in the glass itself, or as a phosphor*
(EPA 1989). Except for its use in colorants and glazes, the use of cadmium
associated with glass and ceramics is less than 5 percent of the total
production of cadmium (Blythe 1990, Cadmium Council 1989). The use of cadmium
in the production of colorants is discussed in Chapter II on plastics.
Cadmium- and lead-based glazes and enamels used with glass/ceramic products
are discussed in the following section.
3. Use of Lead in Enamels and Glazes
a. Applied to Metal
Lead compounds are used in enamel compositions as fluxing
agents (i.e., to aid the softening or melting of the enamel). This allows the
successful application of the enamel at relatively low temperatures. As
fluxing compounds, lead compounds offer the advantage of increasing the
brilliance and smoothness of the enamel even when used in large quantities.
Lead also increases resistance to chipping, improves elasticity, and increases
corrosion resistance. The amount of lead in an enamel will depend on the type
of metal to which it is applied. Enamels used on cast iron contain only from
0 to 3 percent lead bisilicate.
Using lead enamels on steel broadens the types of steel that can be
successfully enameled. When enamels are applied below the strain point of the
steel, the strength and warpage characteristics are not damaged. The flux
characteristics of lead allow enamels to be applied below this point. Lighter
A phosphor is a phosphorescent substance that emits light when excited
by radiation. Common applications include mercury-vapor lamps and fluorescent
tubes (EPA 1989).
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gauge steel can be used as a result. Typical leaded enamels applied to steel
contain between 2 and 7 percent lead.
Enamels used on the limited number of aluminum alloys that can be coated
are all leaded. These enamels can contain between 30 and 45 percent lead
oxide. The use of lead in the enamel is necessary because of the low maturing
temperature of aluminum.
b. Applied to Glass
Glass color enamels are used to decorate and label glass
objects. Lead enamels are used for glassware primarily as a flux. The lower
melting points which can be achieved with lead are important in preventing the
glassware from deforming during firing.
Four properties are important for glass enamels: stability of
composition, chemical durability, coefficient of expansion, and melting
temperature. Stability is necessary so that the enamel will not react to form
compounds which will be harmful to the color or the item. Chemical resistance
to acids and alkalies serves to protect enamels from damage in their contact
with food, dishwasher detergents, or attack by weather. Enamels must expand
slightly less when heated than the host to which they are applied or the
enamel will craze, peel, or crack when fired. Glass enamels must have a
melting temperature far enough below the softening point of the preformed
glass to which they are applied so that the article will not be deformed.
Formulation of enamels for glassware is also similar to the formulation
enamels used on metals. The requirement for lower firing temperatures
generally increases the use of flux agents. Lead oxide is the primary flux in
glass enamels. Due to concerns about the toxicity of lead, industry has put
significant effort in reducing lead in enamels used to decorate glass. Most
of the progress has resulted in enamels which prevent the lead from becoming
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soluble in a range of acidities, thus preventing glassware from posing
toxicity concerns during use. Most enamels, however, are still based on lead
flux. These enamels contain 50 percent lead oxide.
c. Glazes
Lead also is used in glazes for ceramics as a flux or
softening agent. Lead glazes are generally more tolerant to application
variables than non-lead glazes. They can be fired at lower temperatures, and
resist crazing, cracking or splitting due to expansion and contraction during
firing, The lower temperatures attained allow the use of a broader range of
pigments (Nordyke 1984). Glazes can contain 50 to 60 percent lead oxide (EPA
1989).
4. Use of Cadmium in Enamels and Glazes
Cadmium is used in glazes and enamels as a pigment (e.g., cadmium
sulfoselenide red) and as a stabilizing agent -of the cadmium pigment (cadmium
oxide). Without the stabilizer, the cadmium pigment would become black under
firing (Nordyke 1984). The use of cadmium as a pigment is discussed in the
chapter on plastics (Chapter II).
C. Consumption of Lead and Cadmium in Glass/Ceramics Products
Table 33 lists the discards of lead in glass/ceramic products from 1970
to 1986. Leaded glass used in televisions accounts for by far the largest
quantity of lead discards, representing 85 percent of the lead in
glass/ceramic products discarded in MSW in 1986. Discards of lead from glass
and ceramics in MSW are expected to steadily increase and are projected to
rise to 91,000 tons by the year 2000 (EPA 1989).
Table 34 presents the discards of cadmium in pigments for glass,
ceramics, and miscellaneous products. Use of cadmium in glass and ceramic
products accounts for a relatively minor portion of cadmium discards in MSW.
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Table 33. Discards of Lead in Glass and Ceramics in MSW
Year
1970
1975
1980
1986
Discards of
Lead from Glass
in TV Sets"
(tons)
10,395
17,969
27,756
52,247
Discards of
Lead from
Light
Bulb Glass"
(tons)
491
506
635
672
Discards of
Lead from All Other
Glass and Ceramics0
( tons )
3,366
3,934
5,235
7,795
Total Lead
Discards
from Glass
and
Ceramics
(tons)
14,252
22,409
33,626
60,714
Includes adjustment for imports. TV's are assumed to have an 8 year
life.
b Light bulbs are assumed to be discarded one year after manufacture.
c All other glass and ceramics are assumed to be discarded 3 years
after manufacture.
Source: EPA 1989.
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Table 34. Discards of Cadmium in Pigments for
Glass, Ceramics, and Miscellaneous Products in MSW
Total Discards of
Cadmium Cadmium in Pigments
Discarded in Cadmium Discarded for Glass, Ceramics
Pigments for in Pigments for and Miscellaneous
Glass and Ceramics* Miscellaneous Products1" Products0
Year (tons) (tons) (tons)
1970
1975
1980
1986
32
27
23
29
79
65
56
70
111
92
79
99
a Half of the glass and ceramics with cadmium pigments is assumed to
end up in MSW. Discards are assumed to be in the year of manufacture
for the glass product. The cadmium used to stabilize cadmium pigments
in glass and ceramics is assumed to be included with the figures for
the cadmium in the pigments.
b Includes pigments in products other than plastics, rubbers, and
glass/ceramics. Products are assumed to be discarded in the year of
manufacture.
0 Includes pigments other than those found in rubbers and plastics.
Source: EPA 1989.
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In 1986, 29 tons of cadmium were discarded in glass/ceramic products. This
quantity is less than 2 percent of the total cadmium discarded.
D. Potential Substitutes for Lead and Cadmium in Glass/Ceramic Products
Substitution for lead- and cadmium-based glass/ceramic products usually
involves switching to alkaline earth metals* (primarily strontium and
barium), and zirconium that are expensive in comparison to lead and cadmium.
In the case of potential substitutes for lead-based glass/ceramic products,
the performance properties of the substitutes lack the refractive indices, the
radiation absorption characteristics, and the processability of lead-based
glass/ceramic products. There are also reports of supply problems with
strontium and zirconium (Corning 1989c). Table 35 presents the potential
substitutes for lead and cadmium in glass and ceramic products.
1. Television and X-ray Shielding Parts
Zirconium is a potential substitute for lead in faceplates, but
its use would increase the cost of the faceplate by six percent (Corning
1989c) . Zirconium products would require higher processing temperatures
necessitating possible changes in manufacturing equipment. Television
manufacturers have already begun to use zirconium-based faceplates that
provide better resistance to radiation darkening (browning) than lead-based
faceplates (Corning 1989c).
Strontium and barium are potential substitutes for the funnel and neck
portions of X-ray shielding substitution but as much as 50 percent more
strontium carbonate than lead oxide would be required to achieve the sane
radiation protection at current thicknesses of funnels and necks. A similar
percentage increase of barium carbonate would be required to substitute for
* Alkaline earth metals include calcium, barium, strotium, and radium
(i.e., Group IIA fo the Periodic Table).
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Table 35. Potential Substitutes for Lead and Cadmium in Glass and Ceramics
Use
Potential
Substitute
Comments on Potential
Substitutes
GLASSES
Television Parts:
Neck and Funnel
(28 and 22
percent PbO
respectively)
Faceplate
(panel) (2
percent PbO)
Leaded Glass:
X-ray shielding
Neon/Fluoroe-
scent Tubing
Light Bulb
Optical Glass
Strontium
Barium
Zirconium
Thicker glass
Strontium/Barium
Cerium/Alkaline
Earth Metals
Barium/zinc oxides
Zinc, lithium and
barium oxides
Processing
problems, lower
durability, larger
quantity required
Supply problem,
marginal cost
difference (6
percent higher)
Increased space
requirements and
decreased visual
clarity
t Expensive
Processing problems
Under development;
processing problems
Lower index of
refraction
achievable than
with lead
Commercially
available
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Table 35. Potential Substitutes for Lead and Cadmium in Glass and Ceramics
(Continued)
Potential Comments on Potential
Use Substitute Substitutes
CERAMICS
Glazes/Enamels Zirconium dioxide Satisfactory
brilliance and
PZT/PZLT (68 percent Chrome tin salt alkali resistance;
PbO) some application
Barium Lead Titanate problems
(10 percent lead)
Color instability
Not as piezoelec-
trically efficient;
less expensive;
can't be used in
temperatures over
100"C; 25 percent
less expensive
Quartz
Not as piezoelec-
trically efficient
3-4 times more
expensive
Rochelle Salts
Not effective in
humid environment;
more efficient
Sources: Blanche 1989; Corning 1989a, 1989b, 1989c, 1989d; Degussa 1989;
Piezo Kinetics 1989; Sylvania 1989.
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lead oxide (Corning 1989d). Significant processability and durability
problems exist with strontium and barium glass products and reformulation
costs could be substantial. The costs of strontium and barium are higher than
lead (Corning 1989d). To achieve the required density associated with proper
x-ray shielding, a 50 percent weight increase would be necessary. This
increase would raise the costs of substitute funnels and necks even more as
well as increasing the technical processing problems (Corning 1989d).
2- Fluorescent Tubine and Light Bulbs
Bismuth alloys containing smaller amounts of lead oxide are
potential substitutes for neon sign tubing (Piezo Kinetics 1989). Cerium and
other alkaline earth metals have been suggested as potential substitutes for
outer envelopes used in fluorescent lighting and for the flare and exhaust
tube used in light bulbs. These potential substitutes lack the processability
and durability of lead based products (Sylvania 1985).
3. Optical and Ophthalmic Glass
Based on refraction indices, substitution to barium and zinc
oxides is possible in optical glass requiring refractive indices below
approximately 1.6 (Nordyke 1984). Lanthanum is a potential substitute for
ophthalmic and non-ophthalmic optical glass requiring high indices of
refraction (above 1.6); however, research is still preliminary (Schotts 1989).
One industry contact noted that in addition to the technical feasibility of
lanthanum substitution being unknown, the cost of this substitution would be
very high (Corning 1990).
4. Lead Crystalware
By definition, substitute glassware that does not contain at least
the specified percentage of lead oxide would not be considered lead
crystalware. Although the functional aspects of leaded crystalware could be
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replaced many of the quality aspects could not. For example, the smoothness
and temperature stability of lead crystalware is hard to replace with other
compounds (ProChem Tech 1989); unleaded glass such as lime glass could be
considered a substitute, but many of the properties of leaded glass (e.g.,
brilliance, strength, and clarity) could not be maintained.
5. Piezoelectric Ceramics
Three potential substitutes for lead-based PZT and PZLT ceramics
have been mentioned by industry sources. A reduction in lead content from
about 68 percent lead oxide to about 10 percent lead oxide can be achieved by
switching to barium titanate products (Piezo Kinetics 1989). Barium titanate
was the first commercially available ceramic and is still widely used in sonar
detection and ultrasonic cleaning devices. Barium titanate is about 50
percent as efficient as PZT (i.e, less voltage produced for a given mechanical
displacement) and barium titanate cannot be used at temperatures above 100*C
(Piezo Kinetics 1989). PZT can be used at temperatures up to 300°C. The cost
of barium titanate piezoelectric ceramics is about 25 percent less than PZT
(Piezo Kinetics 1989).
The temperature limitation makes barium titanate unsuitable for use as
an igniter in glass appliances and cigarette lighters. In general, due to the
lower cost of barium titanate it has already been substituted for PZT where
feasible. Some additional substitution may be possible, but with a sacrifice
in performance in other consumer electronic applications.
Quartz is also piezoelectric and is used in applications such as radio
tuners that require a high degree of frequency control. Quartz costs 3 to 4
times more than PZT and is 10 to 20 percent less efficient (Piezo Kinetics
1989).
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The final potential substitute is Rochelle salts. Although they are 25
to 30 percent more efficient than PZT, they do not work well in humid
conditions, including most ambient air, making them unsuitable for most
applications (Piezo Kinetics 1989).
6. Glazes and Enamels
a. Lead-Free Glazes and Enamels
Lead free enamels were introduced in the early 1980s and
have found application on lighting fixtures and liquor and cosmetic
containers. Because their chemical resistance is much lower than that of
standard lead-based enamels, they are finding a relatively limited use.
According to Nordyke (1984), no lead-free systems are available for use on
cookware, tableware, and other areas that demand excellent chemical
resistance. In a typical glass enamel, lead oxide accounts for 56 percent ofe
the formulation. The lead oxide can be replaced by using a formulation with
up to 40 percent zinc oxide (ZnO), lithium oxide (Li20), calcium oxide (CaO) ,'
barium oxide (BaO), and antimony oxide (SbO), and the remaining 16 percent can
be allocated to other ingredients of the formulation.
In addition, an enamel system free of lead and cadmium consisting of
zirconium dioxide (Zr02) has been recently developed (Gillier 1989). Used for
glass decorating, the enamel has high brilliancy and alkali and dishwasher
resistance. The enamel system can be colored with pigments to 13 shades. The
range of colors available is specifically intended for the decoration of
dinnerware, glass-ceramics, and borosilicate and opal glass but does not
include red or bright yellow without the use of cadmium.
With the absence of lead, lack of brilliance is a problem. Lithium is
added to improve brilliance, but this can have a negative effect on the glass
to which it is applied due to ion exchange, thereby weakening the glass. In
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addition, these enamels have higher and narrower firing temperatures than
leaded enamels (Degussa 1989).
Potential substitutes for lead in glazes appear to be scarce because of
the number of excellent properties currently available from lead-based glazes.
As discussed earlier, these properties include fusibility, smoothness,
brilliancy, and mechanical and chemical resistance. A potential substitute
consisting of a chrome-tin salt has been identified for pink glazes (Blanche
1989). More development work is required on this compound because of color
instability in lead-free glass. Lead-free decorative glazes are also being
developed, but they are experiencing difficulty because the lead-free glazes
actually encourage greater release of lead from the leaded glazes over which
they might be applied (Degussa 1989).
The cost of these unleaded glazes and enamels is not significantly
different than leaded versions, but they may add to the cost of the final
product due to higher firing temperatures and more precise processing
conditions that would be required (Degussa 1989).
b. Cadmium
As mentioned earlier, cadmium is used in glazes and enamels
as a color stabilizer for cadmium pigments (bright reds and yellows). Cadmium
pigments are discussed in the plastics chapter and Chapter II.
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E. References
Blanche, S.I. 1989. "Chrome-Tin Pink Glazes," Ceramic Engineering Scientific
Proceedings. Vol. 10, pp. 65-68.
Blythe Colours. 1990 (March 27). G.R. Streatfield, Technical Director,
Cresswell Stoke-on-Trent, England. Comments on draft of " Use and Substitutes
Analysis For Lead and Cadmium Products in Municipal Solid Waste.
BCR 1990 (March 5). British Ceramic Research Limited. D.W.F. James, Chief
Executive. Penhull Stoke-on-Trent, England. Comments on draft of "Use and
Substitutes Analysis For Lead and Cadmium Products in Municipal Solid Waste."
Cadmium Council. 1989 (May 25). H. Morrow. Transcribed telephone
conversation with Peter Weisberg, ICF Incorporated, Fairfax, VA.
Corning Glass. 1989a (July 21). T. Seward. Transcribed telephone
conversation with Peter Weisberg, ICF Incorporated, Fairfax, VA.
Corning Optics. 1989b (July 21). R. Thompson. Transcribed telephone
conversation with Peter Weisberg, ICF Incorporated, Fairfax, VA.
Corning Glass. 1989c (May 30). D. Lopata. Transcribed telephone
conversation with Peter Weisberg, ICF Incorporated, Fairfax, VA.
Corning Glass. 1989d (July 26). J. Connelly. Transcribed telephone
conversation with Peter Weisberg, ICF Incorporated, Fairfax, VA.
Corning Glass. 1990 (October 3). C. McCarthy. Letter to Gary Cole, U.S.
Environmental Protection Agency, Washington, DC.
Degussa Corporation. 1989 (August 14). D. Gillier. Transcribed telephone
conversation with Louis Gardner, ICF Incorporated, Fairfax, VA.
EPA. 1989 (January). U.S. Environmental Protection Agency. Characteristics
of Products Containing Lead and Cadmium in Municipal Solid Waste Facilities
1970 to 2000. Prepared by Franklin Associates Ltd., Prairie Village, KS.
Gillier, D. 1989 (February). "Beauty and the Beast: Colors Shine Without
Lead," Ceramic Industry, pp. 21-22.
Nordyke, J.. 1984. Lead in the World of Ceramics. The American Ceramic
Society. Westerville, OH.
Piezo Kinetics Inc. 1989 (May 30 and July 27). R. Turner. Transcribed
telephone conversation with Peter Weisberg, ICF Incorporated, Fairfax, VA.
Pro Chem Tech. 1989 (May 31). T. Keister. Transcribed telephone
conversation with Peter Weisberg, ICF Incorporated, Fairfax, VA.
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Schotts Glasswerke. 1989 (July 27). R. Scheller. Transcribed telephone
conversation with Peter Weisberg, ICF Incorporated, Fairfax, VA.
Sylvania and Laxman Ltd. 1989 (June 1). R. Marlor. Transcribed telephone
conversation with Peter Weisberg, ICF Incorporated, Fairfax, VA.
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VIII. BRASS AND BRONZE PRODUCTS
A. Overview of the Copper Alloys Industry
Copper is combined with varying amounts of other metals to produce,
among other alloys, brass and bronze. The properties of these alloys are
varied by incorporating certain materials to fit a wide range of uses. Copper
alloys generally have good mechanical properties, corrosion resistance,
workability, and conductivity. Lead is included in some forms of brass and
bronze to improve workability (Copper Development Association 1989).
Brass is generally an alloy of copper and zinc with small additions of
other metals. Brass products may be cast or formed by rolling, extrusion,
forging or other processes. The varieties of brass are defined by their
content: red-gold brass is 75-85 percent copper, yellow brass consists of 60
to 70 percent copper, naval brass contains 2 percent tin, and leaded brasses
contain lead in quantities greater than 2 percent (EPA 1989). Typically 3
percent lead is found in free machining brass (Kirk-Othmer 1978).
Lead is generally added to brass to improve the free machining
characteristics of the alloy (Copper Development Association 1989, Wolfenden
and Wright 1979) . Lead also may be present as an impurity in some brass
products due to the lead content of scrap materials used in the manufacture of
brass materials. Lead is present, therefore, in virtually all kinds of brass
to a small degree (Kirk-Othmer 1978).
Traditionally, bronze has been defined as an alloy of copper and tin,
but currently is described as containing any of a variety of metals including
aluminum, manganese, silicon, or tin in combination with copper, which is
always the principle ingredient. Leaded bronze may contain up to 30 percent
lead (EPA 1989) which is included because it improves workability and
conformability (Kirk-Othmer 1978). In general, bronzes can be grouped into
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leaded, tinned, and high strength bronzes with the latter groups being
successively harder and stronger (Kirk-Othmer 1978, Glaeser 1983).
1. Use of Lead in Brass
Because lead is insoluble in copper it remains as free lead
globules distributed throughout the alloy. The lead globules lend the alloys
the properties associated with softness such as improved lubrication
characteristics, decreased fatigue strength, and improved conformability
(Concast Metal Products 1989, Glaeser 1983). The improved machinability that
lead adds to leaded brass has led to its use in the manufacture of screw
machine parts and plumbing goods (Copper Development Association 1989).
Leaded brasses are not used in the majority of copper alloy applications
because these properties are not needed and the increased lead reduces other
important properties such as light weight, conductivity and strength (Copper
Development Association 1989).
2. The Use of Lead in Bronze
Leaded bronze is used mainly in machine parts such as bushings and
bearings where the lead adds to the natural lubricity of the parts and
decreases the likelihood of mechanical seizures due to interruption or loss of
lubricant (Concast Metal Products 1989). The conformability of leaded bronze
allows parts to wear into best fit through use (Glaeser 1983) . Highly leaded
bronzes are not used where impact or heavy, oscillating loads may be
encountered as a consequence of their lower strength and hardness. Lead also
produces hot shortness (brittleness under red-heat), and therefore exceeding
the maximum frictional temperature is of concern (Glaeser 1983).
B. Consumption of Lead in Brass and Bronze
Due to the narrow scope of applications, the majority of end products
made from leaded brass and bronze are not disposed in MSW, but rather in
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industrial waste facilities. Table 36 shows lead in brass and bronze
discarded at MSW for the period from 1970-1986.
C. Potential Substitutes for Lead in Brass and Bronze
Two methods can be used to substitute for lead in brass and bronze.
Alternative metals can be incorporated with copper to produce alloys with
similar properties to lead-containing products or alternative materials (e.g.,
plastics or other materials) can be used in the final products. It is easiest
to consider potential substitutes by use since leaded brass and bronze share
many functions.
Bearings and fittings made from unleaded tin bronze and aluminum bronze
are already used for heavier load applications for which leaded bronze is not
hard enough. These products could be used for the softer leaded bronze, but
would lack the natural lubricity of leaded bronze. A lubricant such as grease
or silicon would be required to prevent equipment seizure when fabricating
certain items made from these harder materials (Concast Metal Products 1989,
Kirk-Othmer 1978). The hardness of these replacements would also necessitate
that other parts with which they come in contact during use be made from
equally hard materials. Engineering and design of machinery would also need
to be more precise due to the loss of wear-in properties associated with
leaded brasses and bronzes (Concast Metal Products 1989, Glaeser 1983).
Machinable leaded brass and bronze used for screw parts and plumbing
fixtures can be substituted for by other copper alloys to a large degree. The
addition of tellurium, selenium, or sulfur offers the possibility of improving
the machining characteristics of copper and its alloys without the use of
lead. These materials affect the metallurgy of copper in ways analogous to
the effect provided by lead. Selenium, tellurium and sulfur also are
insoluble in copper and thus remain as free globules which provide points in
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Table 36. Discards of Lead in Brass and Bronze in MSV
Year
1970
1975
1980
1986
Domestic
Lead Discards'
(tons)
20,485
23,699
20,044
15,660
Lead in
Imports/Exports15
( tons )
N/A
N/A
165
405
Gross
Discards
(tons)
20,485
23,699
20,209
16,065
Net Discards
into MSWC
(tons)
410
474
404
321
N/A - Not Available.
a Assumes 10 year product life. Quantities are amounts of lead
consumed in brass/bronze production ten years earlier.
b Data not available some years. Negative numbers denote net
exports.
c Assumed to be 2 percent of all discards.
Source: EPA 1989.
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the microstructure for breaks to form. They do not provide, however,
machinability at the same level as lead and increasing the consumption has a
rapidly diminishing effect. Compared to free-cutting brass (61 percent Cu, 3
percent Pb, 36 percent Zn) as a standard of 100, copper has a machinability
rating of 20, and sulfur copper (99.7 percent Cu, 0.3 percent S) and tellurium
copper (99.5 percent Cu, 0.5 percent Te) both have a machinability rating in
the range of 85-90. The effect of adding these materials is the same for many
other brass alloys and for the tin bronzes (Kirk-Othmer 1978, Copper
Development Association 1989).
The choice of a potential substitute depends to a large extent on the
properties that the consumer requires most. Different substitutes will be
chosen if hardness, color, strength, or another property is critical or must
remain constant. The costs of potential substitute alloys depend on the costs
of their components which are subject to the influence of world markets.
Table 37 presents substitute products and some of their disadvantages. Table
38 presents costs for some representative lead-containing and potential
substitute alloys.
Other potential substitutes for leaded brass can replace specific end
products. For example, some plumbing fixtures and valves currently
manufactured with brass or bronze may be replaced by PVC or other plastic
materials (Cohen 1987), but these materials are not suitable for the bulk of
brass and bronze applications. Machined screws may be replaced by steel
screws or another machinable metal depending on the importance of corrosion
resistance (Concast Metal Products 1989).
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Table 37. Potential Substitutes for Lead-based Brass
and Bronze Products
Use
Potential Substitute
Disadvantages
Machined Products
Plumbing
Fixtures,
Machine screw
parts
Bushing/Bearing
Products
Steel
PVC
Tellurium bronze
Selenium bronze
Sulfur bronze
Tin bronze
Aluminum bronze
Manganese bronze
Poor corrosion
resistance
Not able to handle all
applications; poor
shear resistance
Not commercially
available; marginal
difference in
machinability
Not commercially
available; marginal
difference in
mach inab i1i ty
Not commercially
available; marginal
difference in
machinability
Harder, requires
lubrication
Harder, requires
lubrication
Harder, requires
lubrication
Sources: Copper Development Association 1989, Nielsen Undated,
Kirk-Othmer 1978.
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Table 38. Cost: Lead-based Brass and Bronze Products
and Their Potential Substitutes
Cost
Product ($/lb)
Machined Products
Leaded brass $1.10
Leaded bronze $1.40
Steel $0.45
PVCa $1.24
Tellurium bronzeb $3.00
Selenium bronzeb $3.00
Sulfur bronzeb $3.00
Bushing/Bearing Products
Leaded bronze $1.40
Tin bronze $2.00
Aluminum bronze $0.70
Manganese bronze $0.70
8 Costs presented for PVC are based
on a comparison of new products (e.g.,
PVC products cost an average of 13
percent more than equivalent brass
parts).
b Not widely available so costs are
rough estimates based on inputs
(Copper Development Association).
Sources: Nielsen undated, Copper
Development Association
1989, Wall Street
Journal 1989, Channel 1989.
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D. References
Channel Hardware Store. 1989 (August 14). Fairfax, VA. Survey of
merchandise prices performed by Louis Gardner, ICF Incorporated.
Cohen, Arthur. 1987 (September). Copper and Copper Alloy Tube and Pipe.
ASTM Standardization News. pp. 54-59.
Concast Metal Products. 1989 (July 20). M. Barber. Pittsburgh, PA.
Transcribed telephone conversation with Louis Gardner, ICF Incorporated,
Fairfax, VA.
Copper Development Association. 1989 (July 21). A Cohen. Greenwich, CT.
Transcribed telephone conversation with Louis Gardner, ICF Incorporated,
Fairfax, VA.
EPA. 1989 (January). U.S. Environmental Protection Agency. Characterization
of Products Containing Lead and Cadmium in Municipal Solid Waste Facilities
1970 to 2000. Prepared by Franklin Associates Ltd., Prairie Village, KS.
Glaeser, WA. 1983 (October). Wear Properties of Heavy Loaded Copper Base
Bearing Alloys. Journal of Metals, pp. 50;55.
Kirk-Othmer. 1978. Encyclopedia of Chemical Technology. John Wiley and Sorts
Publishing Co. Inc. Volume 3, pp. 674-77. Volume 7, p. 45.
Nielsen, WD. Undated. Metallurgy of Copper Base Alloys. Casting Engineering
& Foundry World. Reprint.
Wall Street Journal. 1989 (July 27). Commodity Prices.
Wolfenden, A. and Wright, PK. 1979 (August). Role of Lead in Free-Machining
Brass. Metals Technology, pp. 297-301.
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IX. CADMIUM-PLATED PRODUCTS
A. Overview of the Plating Industry
Plating can be defined as the application of metallic coatings to
various items in order to provide the base material to which they are applied
with surface properties of the metal that is used as a coating. Coatings
provide protection to plated materials by one of five methods: by protecting
the substrate by setting up a favorable electrochemical potential, by forming
a protective, passive film in aqueous media, by coating the substrate with a
slow oxidizer that protects the substrate at high temperatures, by acting as a
barrier to corrosive agents (e.g., noble metals), and finally, by providing
wear resistance by forming compounds that are much harder than the unplated
substrate (Kirk-Othmer 1978).
1. Plating Technologies
Several technologies are used to apply metallic coatings. The
particular process that is used depends on the properties of the substrate and
coating material. Electroplated coatings are formed by electrodeposition of
the coating material on the substrate, usually in an aqueous solution in which
ions of the coating material are dispersed. The ions are applied to the
substrate material by providing electrical current to the solution (Kirk-
Othmer 1978). Another process, diffusion coating, places the coating material
(in the liquid, solid, or vapor phase) in physical contact with the substrate
at an elevated temperature, thereby creating interdiffusion of the two
materials at the surface (Kirk-Othmer 1978).
Sprayed coatings are applied to materials which cannot be easily coated
by other means due to the size, shape, or susceptibility to damage by heat.
In addition, some coatings can be applied by mechanical methods or liquid
metal cladding where the materials are brought into physical contact by force
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to disrupt oxide films on the surface of each, thereby allowing a
metallurgical bond to form (Kirk-Othmer 1978).
Chemical coating is an electroless plating technique which involves a
catalytic chemical reaction reducing a species to a metallic or compound
material which forms the coating. These reactions are temperature dependent
and can require temperatures from 500 to 1500"C. Future development may allow
these reactions to take place at lower temperatures. Finally, vacuum coatings
transfer the coating metal in the vapor phase through heat or a ballistic
process to the substrate. The use of vacuum allows this process to take place
without interference from contaminating materials (Kirk-Othmer 1978).
2. Cadmium Plating
Cadmium plating is used on fabricated steel and cast iron parts
and can be electroplated on plastics or metal in some appliance and consumer
applications. Cadmium is used because it has a combination of properties:
natural lubricity, corrosion resistance to salt water and alkalis, high
deposition rate in application, good solderability and ductility, and a long-
lasting silvery-white luster (Kirk-Othmer 1978, Humphreys 1989).
Cadmium plating is used to protect bolts and screws used in marine
applications from corrosion due to prolonged exposure to moisture and salt.
In general, cadmium plated products have a longer service life due to their
corrosion resistance and natural lubricity which helps in applications where
mechanical seizures would impair function. Automotive uses such as seat belt
fasteners and brake linings are examples of applications for which these
features are important (Cadmium Council 1989). Cadmium plated fasteners also
are used because their natural lubricity reduces the torque experienced during
fastening which could cause fatigue (Humphreys 1989).
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B. Consumption of Cadmium in Electroplating
General use of cadmium plating has declined for two reasons: 1) the
toxicity of cadmium itself and 2) cadmium traditionally has been plated on
surfaces using a cyanide bath which manufacturers also avoid because of health
and disposal problems. However, newer solutions involving trivalent chromium
are being developed and have helped to revive to a certain extent cadmium's
use in plating (Humphreys 1989).
The disposal of cadmium plated products in MSW will continue to decline
over the next few years because users have substituted for these products (EPA
1989). The bulk of the remaining applications for cadmium plating are in the
automotive, aerospace, and military markets that are disposed in solid waste
facilities other than MSW. In general, there has been a decrease in the
disposal of cadmium plated articles including dishwashers, washing machines,
radios, and televisions in MSW because substitutes are currently in place for
cadmium-plated parts in these applications. Table 39 shows the discards of
cadmium in plated parts for home appliances and electronics for the period
between 1970 and 1986. Due to the changes in materials that have already
occurred the total discards to MSW of cadmium in plated products in the year
2000 are anticipated to be only 29 tons (EPA 1989).
C. Potential Substitutes for Cadmium in Metallic Coatings
Potential substitutes for cadmium in plating operations can be
classified into two groups: alternative materials and technologies which do
not require the properties imparted by cadmium plating and alternative
coatings with similar properties that can be used in place of cadmium.
The substitution which has already taken place in the majority of
household applications has used alternative materials. Cadmium in washing
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Table 39. Discards of Cadmium in Plated Parts for
Home Appliances and Electronics in MSV
Discards in Discards in Total Discards
Major Appliances* Consumer Electronicsb in MSW
Year (tons) (tons) (tons)
1970
1975
1980
1986
47
39
32
24
571
330
176
161
618
369
208
185
Note: Total discards of cadmium plated parts in MSW are expected to be
29 tons in year 20'00.
Assumes 8 year lifetime for appliances and includes adjustment for
cadmium recovered with ferrous parts.
b Assumes 8 year lifetime for products and includes an adjustment
for imports and exports.
Source: EPA 1989.
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machines and dishwashers has been largely replaced by the increased use of
plastics which do not require cadmium plated bolts to hold the frames
together. Similarly, the technology that used cadmium plated chassis in
radios and televisions is obsolete. Steel chassis that were plated with
cadmium have been replaced by printed circuit boards made of resinous
materials (EPA 1989).
Additional substitution for cadmium plating may use similar technology
changes or alternative coatings. The choice of replacement plating will
depend upon which properties of cadmium coating are most important. Although
inferior in terms of solderability and lubrication, zinc is already used
whenever possible because of reduced health and environmental concerns (Ajax
Metal Processing 1989). Electroplated tin and gold are readily solderable,
although gold is very expensive. Tin is not effective in corrosion
resistance, but the development of tin-zinc alloys and a zinc-nickel alloy as
possible substitutes for cadmium is progressing (AESF 1989, Kirk-Othmer 1978).
Chromizing also is an economical process to improve corrosion resistance of
steel where appearance is not important. Chrome offers the advantage of a low
friction surface and good wearability (Kirk-Othmer 1978), but does not offer
the same corrosion resistance as cadmium. Table 40 identifies the
characteristics of potential substitute plating technologies and alternate
products that can or have replaced cadmium plated parts in many applications.
Table 41 provides representative costs for these potential substitutes.
As the tables indicate, there is a trade-off between cost,
processability, and corrosion resistance for plating technologies that replace
cadmium plating. For most applications that enter MSW, however, a workable
substitute is available or can be developed. In cases when alternate
materials (e.g., plastics) offer superior performance or wear characteristics
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Table 40. Characteristics of Potential Substitutes for Cadmium Plating
Use
Potential
Substitute
Advantages
Disadvantages
Electronics
(Chassis)
Fasteners
(Nuts, Bolts)
Resinous
printed
circuit
boards
Plastic
construction
Zinc plating
Tin plating
Gold plating
Chrome
plating
Already
occurred;
superior
technology
Already
occurred in
consumer
household
appliances
Already
preferred
option where
possible
Good solder-
ability
Good
corrosion
resistance
Good wear
properties
Better
corrosion
resistance
for acids
Not possible
in most
cases
Lower
corrosion
resistance
Loss of
lubricity
Loss of
solder-
ability
Poor
corrosion
resistance
Very
expens ive
Poor wear
resistance
Lower
corrosion
resistance
for salts
and neutral
pH
Sources: AESF 1989, Cadmium Council 1989, Iron Age 1980, Kirk-Othmer 1978.
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Table 41. Costs of Cadmium Plating and Potential Substitutes
Cost/lb. of
Plating Material'
Relative Cost
of Plating
Compared to
Cadmium15
Cadmium
Zinc
Tin
Gold
Chrome
$
$
$
$6,
$
4.50
0.80
5.60
552.00
7.50
1.00
0.50
1.05
1,500.00
1.12
a Weights are all for standard avoirdupois
pounds.
b Relative cost are different from ratio of
metal costs due to overhead and different
thickness requirements.
Source: Cadmium Council 1989, Ajax Metal
Processing 1989, Kirk-Othmer 1978,
Wall Street Journal 1989.
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to cadmium plating, substitution has already occurred to a large extent. It
is also conceivable that these alternative materials can replace other
cadmium-based products that are still in use (e.g., plastic bolts in marine
applications that do not require high shear strength are possible).
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D. References
Ajax Metal Processing. 1989 (July 27). F. Buono. Detroit, MI. Transcribed
telephone conversation with Louis Gardner, ICF Incorporated, Fairfax, VA.
AESF. 1989 (July 31). American Electroplaters and Surface Finishers Society.
W. Safranek. Orlando, FL. Transcribed telephone conversation with Louis
Gardner, ICF Incorporated, Fairfax, VA.
Cadmium Council. 1989 (July 27). H. Murrow. New York, NY. Transcribed
telephone conversation with Louis Gardner, ICF Incorporated Fairfax, VA.
EPA. 1989 (January). U.S. Environmental Protection Agency. Characterization
of Products Containing Lead and Cadmium in Municipal Solid Waste Facilities
1970 to 2000. Prepared by Franklin Associates Ltd., Prairie Village, KS.
Humphreys, PG. 1989 (May). New Line Plates Non-Cyanide Cadmium. Products
Finishing, pp. 80-90.
Iron Age. 1980 (January 14). Cadmium's Plight Opens Field to Alternative
Coatings, p. 50.
Kirk-Othmer. 1978. Encyclopedia of Chemical Technology. John Wiley and Sons
Publishing Co., Inc. Volume 6, p. 166; Volume 8, pp. 827-869. 1981. Volume
15, pp. 241-274.
Wall Street Journal. 1989 (July 27). Commodity Prices.
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X. COLLAPSIBLE TUBES
A. Overview of the Tube Industry
Collapsible Cubes are used to dispense a number of products from
medicines to epoxy resin adhesives. While tubes are manufactured from a
variety of materials, lead tubes are used to dispense corrosive products (lead
is difficult to corrode) or to satisfy customer packaging preferences
(Teledyne 1989).
B. Use of Lead Tubes
Only a few companies still make lead tubes, including Teledyne Packaging
in Pennsylvania and Atlantic in New Jersey. Lead tubes represent a very small
fraction (less than one percent) of the tube market (TCNA 1989a, 1989b). Of
the lead tubes currently manufactured, most'are used for artists colors and
the remainder for corrosive glues. Market surveys show that artists tend to
prefer the relatively heavy lead tubes because of the heft and quality feel
that is added to the paint product (Teledyne 1989).
C. Consumption of Lead in Tubes
The consumption of lead in collapsible tubes reached a peak in 1969 and
has since declined (see Table 42). The decline is attributable to the
increasing use of aluminum for this purpose (EPA 1989). The total discards of
lead in tubes in MSW has dropped from over 9,000 tons in 1970 to about 600
tons in 1985 (EPA 1989).
D. Potential Substitutes for Lead Tubes
The possible substitutes for lead tubes and their performance
characteristics and relative price compared to lead are provided in Table 43.
One of the possible substitutes for lead tubes identified in the table is
aluminum tubes with phenolic epoxy lining. This aluminum technology does not
differ in cost and offers similar performance to the lead tubes.
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Table 42. Discards of Lead in Collapsible Tubes in MSW
Discards of Lead in
Collapsible Tubes*
Year (tons)
1970 9,310
1975 2,860
1980 1,477
1986 639
The lifetime of lead
collapsible tubes before
discard is assumed to be
2 years.
Source: EPA 1989.
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Table 43. Potential Substitutes for Collapsible Lead Tubes
Lead Technology
Substitutes
Comments
Lead Tubes
Aluminum tubes with
phenolic epoxy
lining
Laminate tubes of
plastic and
aluminum
Similar in cost and
performance to lead
tubes
Similar in cost and
performance to lead
tubes
Source: Teledyne 1989,
- 134 -
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The other substitute technology, laminate tubes manufactured with
alternating layers of plastic and aluminum also can replace lead tubes.
Unlike plain plastic tubes that have memory and return to their original
shape, laminate tubes will flatten during use. Laminate tubes and lead tubes
are similar in cost (Teledyne 1989).
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E. References »
EPA. 1989 (January). U.S. Environmental Protection Agency. Characterization
of Products Containing Led and Cadmium in Municipal Solid Waste Facilities
1970 to 2000. Prepared by Franklin Associates Ltd., Prairie Village, KS.
TCNA. 1989a (May 31). Klein, T. Executive Secretary, Tube Council of North
America. New York, NY. Transcribed telephone conversation with Thomas Hok,
ICF Incorporated, Fairfax, VA.
TCNA. 1989b (August 15). McCoy. Assistant to the Executive Secretary, Tube
Council of North America. New York, NY. Transcribed telephone conversation
with Thomas Hok, ICF Incorporated, Fairfax, VA.
Teledyne Packaging. 1989 (May 31). K. Barry . New Jersey. Transcribed
telephone conversation with Thomas Hok, ICF Incorporated, Fairfax, VA.
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XI. OTHER PRODUCTS
There are a variety of other products that contain lead and/or cadmium
and are disposed in MSW facilities. These products account for a very small
percent of the total amount disposed, but are discussed in this chapter for
completeness. The products are:
Foil wine wrappers;
Used oil;
Rubber (elastomers); and
Electric blankets/heating pads.
A. Foil Wine Wrappers
The capsule used to enclose the cork in a wine bottle contains a tin-
lead alloy. The Wine Institute (1989) reports that a tin-lead capsule has
traditionally been used for market recognition and that plastic would be a
viable substitute (EPA 1989) . In addition, some liquor products use aluminum
foil as wrappers. Lead wrappers are easily substituted because the cost of
substitute plastic and aluminum foil wrappers are comparable to that of lead
wrappers, and wrappers do not constitute a significant portion of the cost of
a bottle of wine, but consumers seem to prefer the lead wrappers because of
the appearance of quality that the lead wrapper imparts to the bottle (Wine
Institute 1989). The discards of lead for this use are presented in Table 44.
B. Used Oil
The used oil generated by the do-it-yourself (DIY) automobile sector is
the main source of oil waste entering the MSW. Although the sources of lead,
and, to a lesser extent, cadmium in used oil include the particles of metal
from engine wear and derivatives of gasoline combustion, this analysis is
concerned with the amount of lead contained in the oil before it is used
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Table 44. Discards of Lead in Foil Wine Wrappers in MSW
Year
1970
1975
1980
1986
Lead Foil on
Domestic Wine Bottles*
(tons)
552
321
311
181
Lead Foil on
Imported Winesb
(tons)
39
35
72
22
Total Foil
Discarded0
(tons)
591
356
383
202
8 Assumes to be 10 percent of total domestic lead foil
consumption.
b Estimate based on the ratio of domestic to imported wine
purchases for the given year, assuming that all imported
wines use lead foil wrap.
c Assumes all foil discarded in the year of production.
Source: EPA 1989.
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because it would not be feasible to address the lead and cadmium that is
deposited in oil from other sources given the scope of this analysis.
Organic leaded compounds are used in oil and lubricant additives as
antiwear agents. Antiwear agents produce a surface film to minimize friction
and wear under boundary-lubrication conditions. The role of cadmium in
lubricant additives in used oil is very small compared to that of lead.
Cadmium discards are, therefore, not discussed in this report.
The disposal in MSW of lead in oil and gasoline additives dropped
dramatically over the period 1970 to 1986: from over 1,600 tons in 1970 to
just under 200 tons in 1986. Recycling of used oil and reduction of lead
content have been responsible for this decline. Table 45 presents the
consumption of Lead in used oil that is disposed of in MSW.
A large number of formulations are available that can perform the role
of anti-knock agents and improve lubrication in oil products. Potential
substitutes include iron and zinc organo-phosphates, iron and zinc chlorides,
and iron sulfides. These products are comparable in price to the lead-based
compounds and have essentially the same performance characteristics. Table 46
presents the information on potential substitutes for alkyl lead compounds
used in oil products.
C. Rubber (Elastomer) Products
Rubber products are usually modified by processing with vulcanizing
agents and other additives before they can be used in most applications. Lead
and cadmium compounds are found in a number of these rubber compounding
chemicals including: pigments, fillers, activators, vulcanizers or curing
agents, stabilizers, and plasticizers. Lead metal may also be integrated into
a rubber product such as lead-sheathed hose (EPA 1989).
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Table 45. Discards of Lead in Used Oil in MSW
Year
1970
1975
1980
1986
Estimated Used
Oil in MSW
(tons)
556,257
661,900
673,935
708,772
Average Lead
in Used Oil
(ppm)
2,889
1,606
1,265
268
Net MSW
Discards of Lead
(tons)
1,636
1,261
853
190"
Note: Less than 1 ton of cadmium is expected to be disposed
annually in municipal solid waste. This is based on a
median concentration of 1.4 ppm cadmium (EPA 1989).
a Discards were expected to be about 74 tons in 1988.
Source: EPA 1989.
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Table 46. Potential Substitutes for Alkyl Lead Anti-Knock
Agents Used as Oil Lubricants
Lead Products
Potential Substitute Products
Alkyl Lead Compounds
Iron and zinc organophosphates
Iron and zinc chlorides
Iron sulfides
Source: Kirk-Othmer 1983.
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These products can be broken down into three main types of ingredients
used for rubber compounding: cure systems, protective systems, and pigments.
Cure systems include activators, vulcanizers or curing agents, stabilizers,
and platicizers. Protective systems include fillers and other chemical
additives.
Pigments may be used in elastomers for color identification of two
similar objects, to improve aesthetic appeal, or to match two parts of
different composition with the same color. Examples of these uses include
coloring white walls on tires, backing on carpeting, sporting goods such as
basketballs, rubber bands, rubber-based floor tile, housewares, and clothing
and footwear (Pigment Handbook 1973).
Lead compounds used as activators and vulcanizers in rubber include
litharge (lead oxide), lead peroxide, and lead stearate. Accelerators and
activators may employ inorganic compounds such as lead oxide, red oxide, and
white lead (EPA 1978). Lead dimethyl dithiocarbamate, a vulcanizing agent, is
used in the base compound for V-belt* manufacture.
Discards in MSW of lead and cadmium in rubber products are presented in
Tables 47 and 48. The total input to MSW identified in the EPA (1989) report
for rubber products is considered to be the lead and cadmium pigments used in
rubber. The other lead- and cadmium-containing products in rubber are assumed
not to enter MSW (EPA 1989).
Lead and cadmium are among the least common chemicals used during rubber
formulation, but both metals may be used in dithiocarbamate compounds as
vulcanizers or curing agents. Cadmium acts as an accelerator during the
V-belts and other shaped belts are used in automobile and other engines
to transfer energy from one moving part to another. "V" refers to the
trapezoidal cross section shape which makes the belt hold in place better.
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Table 47. Discards of Lead in Pigments Used in Rubber Products in MSW
Year
Discards of
Lead in
Tire Pigments
(tons)
Discards of
Lead in Fabricated
Rubber Products
(tons)
Total Discards
of Lead in
Rubber Pigments'
(tons)
1970
1975
1980
1986
45
44
83
56
16
15
33
21
52
53
104
70
Ten to fifteen percent of tires and other rubber products are
diverted or recovered annually.
Source: EPA 1989.
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Table 48. Discards of Cadmium Pigments
Used in Rubber Products in MSW
Cadmium in Pigments
for Rubber Products'
Year (tons)
1970 10
1975 13
1980 8
1986 6
* Consumption of cadmium pig-
ments in rubber was assumed to
be one percent of total con-
sumption of cadmium pigments.
Source: EPA 1989.
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curing process, decreasing energy requirements (Gates Rubber 1989). While
other compounds in the dithiocarbamate family may be substituted for lead and
cadmium dithiocarbamate compounds, some changes in the performance of the
final rubber products may occur (Polysar 1989). The use of cadmium in rubber
products improves aging resistance by decreasing the likelihood of hardening
at high temperatures, but neither cadmium nor lead vulcanizing agents are
required for rubber formulation. Zinc dithiocarbamates not only provide an
acceptable chemical substitute for cadmium and lead dithiocarbamates, but zinc
compounds are also less costly.* Table 49 presents potential substitutes for
lead and cadmium vulcanizing agents; discussion of potential substitutes for
pigments can be found in the chapter on plastics (Chapter II).
Lead and cadmium also may be considered part of the protective system of
a rubber compound. Cadmium accelerators tend to improve the aging resistance
of rubber, and lead increases the density and strength of rubber used for
hydraulic lines (Gates Rubber 1989). Lead lubricants also help the rubber
release from commonly used lead molds. However, lead and cadmium are not
essential to protective systems in rubber compounding (Polysar 1989).
D. Printing Inks
Printing inks that are disposed in MSW primarily are used for printing
newspapers, magazines, and packaging for a variety of consumer products.
These inks consist of a dissolved dye or pigment in a vehicle to produce a
fluid or paste that can be transferred to paper, film, foil, or metal. The
solvent then evaporates, leaving the ink on the surface.
* Although their use is not essential, lead and cadmium may still be used
in rubber compounds because of compatibility, customer preference, or price
considerations.
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Table 49. Potential Substitutes for Representative Lead- and
Cadmium-based Vulcanizing Agents
Lead and Cadmium Substitute Other Compounds
Compounds Dithiocarbamates
Lead dithiocarbamate Bismuth Aldehyde -amine
reaction products
Cadmium Copper
dithiocarbamate Benzothiazoles
Selenium
Benzothiazolesul-
Tellurium fenamides
''*.
Zinc Dithiophosphates
Piperidinium Guanidines
Thiazoles Thioureas
Thiurams
Thiocarbamyl
sulfenamides
Other curing agents*
Note: These potential substitutes are presented for completeness even though
this analysis assumes that the total lead and cadmium contribution to
MSW from rubber products is attributable to pigments (EPA 1989).
* Other curing agents include alkylphenol-formaldehyde resin, alkylphenol
disulfides, N,N'-caprolactam disulfide, p-quinonebis(benzoyloxime), 4,4'-
dithiobismorpholine, hexamethylene diamine carbamate, p-quinone dioxime,
sulfur, and insoluble sulfur.
Sources: Kirk-Othmer 1983.
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Printing inks may be classified as organic or inorganic. While both
categories of ink may contain trace elements, inorganic inks contain the
highest levels of lead or cadmium. Organic inks may contain trace amounts of
lead and cadmium as impurities (BASF 1989, EPA 1989). Cadmium is not widely
used for inorganic printing inks; cadmium pigments are very lightfast and tend
to be used in automobile manufacturing* or for printing applications that
demand the pigment withstand chemicals (e.g., a label for an acid bottle) (ICI
1989, ANPA 1989b). Cadmium inks are heavy and do not tend to flow well (ANPA
1989b). Printing inks that contain lead are inorganic and include lead
chromate (yellow and orange) and molybdate orange (ANPA 1989b). Neither lead
nor cadmium are used to make black ink, or in lithographic printing (used to
produce magazines) (ANPA 1989a, 1989b, 1989c).
Relatively little lead is currently used in printing inks. As shown inr
Table 50, discards of lead in printing ink has declined steadily and
substantially since 1970. The amount of ink discarded in 1970 is over 72
times the amount discarded in 1986. This decline in lead use reflects the
general trend away from inorganic pigments toward organic pigments. While
some printing applications (e.g., covering a dark background with a light
color and clear films used in packaging) may demand the use of inorganic
pigments for their excellent opacity (hiding power) and brightness, recently
developed organic pigments also have very good opacity, color, and brightness
(BASF 1989, ANPA 1989b).
Dialyrid yellow and dialyrid orange are the major substitutes for lead-
containing printing inks. These substitute inks are used in newspapers,
magazines, and packaging. Table 51 shows the advantages and disadvantages of
* BASF, a major U.S. ink manufacturer, does not use cadmium in any of its
inks (Wagner 1989).
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Table 50. Discards of Lead in Printing Inks in MSW
Lead Discards in
Printing Inks8
Year (tons)
1970 19,192
1975 13,819
1980 8,222
1986 265
a Lead in ink is assumed to enter MSW in the same year as it is
consumed. Adjustments were made to reflect the industrial disposal
of ink that is removed from recycled paper. Manufacturing losses
were estimated to be 5 percent.
Source: EPA 1989.
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Table 51. Advantages and Disadvantages of Potential Substitute Ink Pigments
for Lead-containing Printing Ink Pigments
Lead-Containing
Ink Pigment
Potential
Substitute
Pigment
Advantages
Disadvantages
Lead Chromate
(yellow or
orange)
Dialyrid Yellow
Does not
contain lead
Molybdate
Orange
Dialyrid Orange
Does not
contain lead
More expensive
than lead
chromate and
lead sulfo-
chromate
Less lightfast
and opaque than
lead chromate
and lead sulfo-
chromate
More expensive
than lead
chromate and
lead sulfo-
chromate
Less lightfast
and opaque than
lead chromate
and lead sulfo-
chromate
Sources: BASF 1989, ANPA 1989a, 1989b.
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the potential substitute inks. While lead-containing inks have better
lightfastness and opacity, the organic substitutes perform well and are
constantly improved through research.*
The opacity of the potential substitute inks can be increased by either
adding titanium dioxide to thicken the ink, or by "sizing" the printing
surface.** The addition of titanium oxide tends to wash out the color of an
ink if enough titanium oxide is added to create good opacity. Dialyrid yellow
and dialyrid orange are more expensive than lead chromate and molybdate orange
(BASF 1989, ICI 1989, ANPA 1989b).
E. Electric Blankets and Heating Pads
Cadmium-containing copper wire has been used in electric blankets and
heating pads. This use has not been characterized and potential substitutes
have not been evaluated because of the extremely low discard volume. It is
likely, however, that other copper alloy wires will be able to fully supplant
the cadmium-containing wires. Table 52 presents the discards in MSW of
cadmium wire for electric blankets and heating pads.
The American Newspaper Publishers Association (ANPA) produces lead-free
ink (trace amounts of lead and cadmium impurities are found in all ink
formulations as a processing by-product); 97 percent of all newspapers
published in the U.S. use ANPA inks (BASF 1989).
"Sizing" a surface means precoating it before the application of ink
such that the ink will provide more even and opaque coverage of the surface.
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Table 52. Discards of Cadmium in Electric Blankets in MSW
Year
1970
1975
1980
1986
Cadmium Discards
(tons)
1
1
1
1
Assumes a product lifetime
of 8 years.
Source: EPA 1989.
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F. References
ANPA. 1989a (August 14). G. Cashau, Director of Technical Research, American
Newspaper Publishers Association, Reston, VA. Transcribed telephone
conversation with Thomas R. Hok, ICF Incorporated, Fairfax, VA.
ANPA. 1989b (August 14). P. Volpe, Technical Coordinator, National
Association of Printing Ink Manufacturers, Westchester, NY. Transcribed
telephone conversation with Thomas Hok, ICF Incorporated, Fairfax, VA.
ANPA. 1989c (August 30). G. Cashau, Director of Technical Research, American
Newspaper Publishers Association, Reston, VA. Transcribed telephone
conversation with Louis Gardner, ICF Incorporated, Fairfax, VA.
BASF. 1989 (August 14). R. Wagner, Manager in Charge of Product Compliance,
BASF, Clifton, NJ. Transcribed telephone conversation with Thomas Hok, ICF
Incorporated, Fairfax, VA.
EPA. 1978. U.S. Environmental Protection Agency. Assessment of Industrial
Hazardous Waste Practices -- Rubber and Plastics Industry, Rubber Products
Industry.
EPA. 1989 (January). U.S. Environmental Protection Agency. Characterization
of Products Containing Lead and Cadmium in Municipal Solid Waste Facilities
1970 to 2000. Prepared by Franklin Associates Ltd., Prairie Village, KS.
Gates Rubber. 1989 (June 1). E. Karger. Denver, CO. Transcribed telephone
conversation with Thomas Hok, ICF Incorporated, Fairfax, VA.
ICI. 1989 (August 3). J. Klein, Lab Manager, ICI Americas Incorporated,
Wilmington, DE. Transcribed telephone conversation with Thomas Hok, ICF
Incorporated, Fairfax, VA.
Kirk-Othmer. 1983. Encyclopedia of Chemical Technology. John Wiley and Sons
Publishing Co. Vol. 14, pp. 493-496; Vol. 20, p. 338.
Pigment Handbook. 1973. Volume 3; First Edition.
Polysar. 1989 (June 1). J. Dunn. Polysar, Canada. Transcribed telephone
conversation with Thomas Hok, ICF Incorporated, Fairfax, VA.12
Wine Institute. 1989 (June 1). W. Lee. San Francisco, CA. Transcribed
telephone conversation with Peter Weisberg, ICF Incorporated, Fairfax, VA.
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