Lead

While new computer monitors with their thinner screens have less lead, it is the old computers sitting on closet shelves that concern environmental groups; lead is also found in the central processing unit (CPU) and in circuit boards.

Timothy G. Townsend and colleagues at the University of Florida in Gainesville disassembled 36 picture tubes produced between 1984 and 1998 by 15 different manufacturers under 21 brand names. Publishing their results in the Oct. 15, 2000 issue of Environmental Science & Technology, they found that lead leaching from the crushed glass of every one of the colour TV tubes and monitors exceeded the U.S. maximum allowable concentrations of 5 mg of lead per litre of water (the Canadian standard is far stricter at 0.010 mg/L), with some glass tainted water containing more than 200 mg/l of lead. When that glass was crushed to pieces less than 5 millimeters in diameter, it had the largest surface area and leached the most-often tainting water with 400 mg/l lead. The researchers conclude that colour picture tubes "should be considered hazardous waste" and kept out of landfills and municipal-waste incinerators.

See also: Characterization Of Lead Leachability From Cathode Ray Tubes Using The Toxicity Characteristic Leaching Procedure
Timothy G. Townsend, Principal Investigator
Florida Center For Solid And Hazardous Waste Management, State University System of Florida
December 1999

The U.S.-based Computer Take Back Campaign (a national network of toxics and waste reduction activists, recycling professionals, local officials, students, and design professionals promoting producer responsibility for discarded computers and consumer electronics) estimates that there are over one billion pounds of lead contained in obsolete computers in the United States. The State of Florida says cathode ray tubes (CRTs) are the second leading source of lead waste after batteries.

Known health effects include damage to the central nervous system, slowed mental development in children, anemia, kidney and reproductive system damage. In 1999, Canadians chucked 1,356 tonnes of lead from computers and monitors into landfills, according to the Enviros RIS report, while the Globe and Mail estimates 15 per cent of all the lead found in municipal waste comes from junked computer monitors.

Mercury

Brominated Flame Retardants

A 1995 study revealed that some of these flame retardants in circuit boards can leach out or be emitted into the surrounding environment. In December 2001, a paper in the journal Environmental Science & Technology reported that North American mothers have breast-milk levels of one type of these flame retardants, polybrominated diphenyl ether (PBDE), at least 40 times the highest concentrations found in Sweden. Sweden has been the leader in implementing legislation to force computer manufacturers to take responsibility for their products. Mans Lonnroth of the Swedish environment ministry observed in 1997, "The product developers of electronic products are introducing chemicals on a scale which is totally incompatible with the scant knowledge of their environmental or biological characteristics."

In the summer of 2002, the Great Lakes Binational Toxics Strategy was specifically warned about these fire retardants used on electronic equipment and computers, which scientists told the group may deserve the same attention as the chemicals it has traditionally been concerned with - PCBs, mercury, lead, and pesticidies. Specific effects of exposure to endocrine disruptors like PBDE include decreased period of lactation, infertility and intellectual impairment in children.

Polyvinyl chloride

Other chemicals of concern include cadmium, lead oxide, barium (all used in circuit boards and CRT monitors) as well as berrylium, hexavalent chromium, and halogenated hydrocarbons in computer plastics, which can result in the formation of dioxin if the plastic is burned. The presence of these chemicals also makes computer recycling particularly hazardous to workers and the environment.

See also Just Say No To E-Waste: Background Document On Hazards And Waste From Computers
by the Silicon Valley Toxics Coalition

Composition of a Desktop Personal Computer Based on a typical desktop computer, weighing ~60 lbs.
Name	Content (% of total weight)	Weight of material in computer (lbs.)	Recycling Efficiency (current recyclability)	Use/Location
Aluminum	14.1723	8.5	80%	Structural, conductivity/housing, CRT, PWB, connectors
Antinomy	0.0094	< 0.1	0%	Diodes/housing, PWB, CRT
Arsenic	0.0013	< 0.1	0%	Doping agents in transistors/PWB
Barium	0.0315	< 0.1	0%	In vacuum tube/CRT
Beryllium	0.0157	< 0.1	0%	Thermal conductivity/PWB, connectors
Bismuth	0.0063	< 0.1	0%	Wetting agent in thick film/PWB
Cadmium	0.0094	< 0.1	0%	Battery, glu-green phosphor emitter/housing, PWB, CRT
Chromium	0.0063	< 0.1	0%	Decorative, hardener/(steel) housing
Cobalt	0.0157	< 0.1	85%	Structural, magnetivity/(steel) housing, CRT, PWB
Copper	6.9287	4.2	90%	Conductivity/CRT, PWB, connectors
Europium	0.0002	< 0.1	0%	Phosphor activator/PWB
Gallium	0.0013	< 0.1	0%	Semiconductor/PWB
Germanium	0.0016	< 0.1	0%	Semiconductor/PWB
Gold	0.0016	< 0.1	99%	Connectivity, conductivity/PWB, connectors
Indium	0.0016	< 0.1	60%	transistor, rectifiers/PWB
Iron	20.4712	12.3	80%	Structural, magnetivity/(steel) housing, CRT, PWB
Lead	6.2988	3.8	5%	Metal joining, radiation shield/CRT, PWB
Manganese	0.0315	< 0.1	0%	Structural, magnetivity/(steel) housing, CRT, PWB
Mercury	0.0022	< 0.1	0%	Batteries, switches/housing, PWB
Nickel	0.8503	0.51	80%	Structural, magnetivity/(steel) housing, CRT, PWB
Niobium	0.0002	< 0.1	0%	Welding allow/housing
Palladium	0.0003	< 0.1	95%	Connectivity, conductivity/PWB, connectors
Plastics	22.9907	13.8	20%	Includes organics, oxides other than silica
Platinum	0		95%	Thick film conductor/PWB
Rhodium	0		50%	Thick film conductor/PWB
Ruthenium	0.0016	< 0.1	80%	Resistive circuit/PWB
Selenium	0.0016	0.00096	70%	Rectifiers/PWB
Silica	24.8803	15	0%	Glass, solid state devices/CRT,PWB
Silver	0.0189	< 0.1	98%	Conductivity/PWB, connectors
Tantalum	0.0157	< 0.1	0%	Capacitors/PWB, power supply
Terbium	0	0	0%	Green phosphor activator, dopant/CRT, PWB
Tin	1.0078	0.6	70%	Metal joining/PWB, CRT
Titanium	0.0157	< 0.1	0%	Pigment, alloying agent/(aluminum) housing
Vanadium	0.0002	< 0.1	0%	Red phosphor emitter/CRT
Yttrium	0.0002	< 0.1	0%	Red phosphor emitter/CRT
Zinc	2.2046	1.32	60%	Battery, phosphor emitter/PWB, CRT

Table presented in: Microelectronics and Computer Technology Corporation (MCC). 1996. Electronics Industry Environmental Roadmap. Austin, TX: MCC.