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628 Waste Management Practices: Municipal, Hazardous, and Industrial
analysis commissioned by the Microelectronics and Computer Technology Corporation (MCC)
estimated that total electronics plastic scrap amounted to more than 525,000 metric tons (580,000
tons) per year. This same study estimated that the largest volume of plastics used in electronics man-
ufacturing (26%) was polyvinyl chloride (PVC). While many computer companies have recently
reduced or phased out the use of PVC, there is still a huge volume of PVC contained in the com-
puter scrap that continues to grow — potentially up to 250 million lb per year (SVTC, 2001). PVC
is a difficult plastic to recycle and it contaminates other plastics in the recycling process.
The use of PVC in computers has been mainly for cabling and computer housings. Most com-
puter moldings are now, however, being manufactured of acrylonitrile-butadiene styrene (ABS)
plastic. PVC cabling is used for its fire-retardant properties but there are concerns that if combusted,
fumes can contribute to fatalities. The production and burning of PVC products generate chlorinated
dibenzodioxins and furans (SVTC, 2001). Hence, there are pressures to switch to alternatives for
safety reasons. Such alternatives are low-density polyethylene and thermoplastic olefins.
Brominated flame retardants are commonly used in electronic products. In PCs they are used
mainly in four applications: in printed circuit boards, in components such as connectors, in plastic
covers and in cables. They are also used in plastic covers of television sets and in domestic kitchen
appliances. Recent research indicates that polybrominated diphenylethers (PBDE) might act as
endocrine disrupters (SEPA, n.d.). PBDEs also form polybrominated dibenzofurans (PBDFs) and
polybrominated dibenzodioxins (PBDDs) during the extruding process (Hoque et al., 1998; SVTC,
2001). The German chemical industry halted the production of these chemicals in 1986 (Brenner,
1986; SVTC, 2001).

22.4 CATHODE RAY TUBES
CRTs are used in computer monitors, televisions and other video display devices. Liquid crystal dis-
plays (LCDs) and plasma displays do not employ CRT technology. In picture production, x-rays are
inevitably generated within the CRT; therefore, Pb is incorporated within the CRT glass to protect
the viewer or user from exposure to x-rays. The average television and PC monitor CRT for the
period between 1995 and 2000 measured 18.6 in. and had a Pb content ranging from 1 to 1.2 kg
(2.14 to 2.63 lb) (EIA, n.d.). Table 22.4 summarizes the weight of glass and the Pb content of var-
ious-sized CRTs manufactured in the United States.
Figure 22.1 shows the locations of Pb within a typical color CRT used in a television or PC mon-
itor. The Pb in the funnel and face plate glass is incorporated (i.e., it is not a simple coating) into the
glass matrix as lead oxide (PbO). This Pb formulation is stable and immobile; in theory, therefore, it
is not expected to leach during the Toxicity Characteristic Leaching Procedure (TCLP; see Chapter
11) or in a landfill environment. The Pb in the frit that joins or welds the face plate glass to the fun-
nel glass is also in the form of a PbO paste. This Pb readily leaches when subjected to the TCLP.
Table 22.5 lists the primary components of the PC or television monitor and their composition.
The CRT cone is an electromagnet that encircles the electron gun at the rear (narrow) end of the
CRT (Figure 22.1). The cone directs the electron beams produced by the electron gun to the faceplate
of the CRT to produce the image. The circuit board processes the incoming signal from the computer
to control the operation of the electron gun in order to provide the correct image on the screen.

22.5 RCRA AND E-WASTES
Recall from Chapter 11 that under The Resource Conservation and Recovery Act (RCRA) a solid
waste is a discarded material, which is:
● Abandoned (materials that are disposed, incinerated, or stored in lieu of disposal)
● Recycled
● Inherently waste-like