Composition of a Desktop Personal Computer Based on a typical desktop computer, weighing 60 pounds. Table presented in: Microelectronics and Computer Technology Corporation (MCC). 1996. Column labels for table: 1. Name of the Content 2. Percent of total weight of computer 3. Weight of Material in Computer (lbs.) 4. Recycling Efficiency (current recyclability) 5. Use and Location of Material 1 2 3 4 5 Plastics 22.9907 13.8 20% Includes organics, oxides other than silica Lead 6.2988 3.8 5% Metal joining, radiation shield/CRT, PWB Aluminum 14.1723 8.5 80% Structural, conductivity/housing, CRT, PWB, connectors Germanium 0.0016 < 0.1 0% Semiconductor/PWB Gallium 0.0013 < 0.1 0% Semiconductor/PWB Iron 20.4712 12.3 80% Structural, magnetivity/(steel) housing, CRT, PWB Tin 1.0078 0.6 70% Metal joining/PWB, CRT Copper 6.9287 4.2 90% Conductivity/CRT, PWB, connectors Barium 0.0315 <0.1 0% Vacuum tube/CRT Nickel 0.8503 0.51 80% Structural, magnetivity/(steel) housing, CRT, PWB Zinc 2.2046 1.32 60% Battery, phosphor emitter/PWB, CRT Tantalum 0.0157 <0.1 0% Capacitors/PWB, power supply Indium 0.0016 <0.1 60% Transistor, rectifiers/PWB Vanadium 0.0002 <0.1 0% Red phosphor emitter/CRT Terbium 0 0 0% Green phosphor activator, dopant/CRT, PWB Beryllium 0.0157 <0.1 0% Thermal conductivity/PWB, connectors Gold 0.0016 <0.1 99% Connectivity, conductivity/PWB, connectors Europium 0.0002 <0.1 0% Phosphor activator/PWB Titanium 0.0157 <0.1 0% Pigment, alloying agent/(aluminum) housing Ruthenium 0.0016 <0.1 80% Resistive circuit/PWB Cobalt 0.0157 <0.1 85% Structural, magnetivity/(steel) housing, CRT, PWB Palladium 0.0003 <0.1 95% Connectivity, conductivity/PWB, connectors Manganese 0.0315 <0.1 0% Structural, magnetivity/(steel) housing, CRT, PWB Silver 0.0189 <0.1 98% Conductivity/PWB, connectors Antinomy 0.0094 <0.1 0% Diodes/housing, PWB, CRT Bismuth 0.0063 <0.1 0% Wetting agent in thick film/PWB Chromium 0.0063 <0.1 0% Decorative, hardener/(steel) housing Cadmium 0.0094 <0.1 0% Battery, phosphor emitter/housing, PWB, CRT Selenium 0.0016 0.00096 70% Rectifiers/PWB Niobium 0.0002 <0.1 0% Welding allow/housing Yttrium 0.0002 <0.1 0% Red phosphor emitter/CRT Rhodium 0 0 50% Thick film conductor/PWB Platinum 0 0 95% Thick film conductor/PWB Mercury 0.0022 < 0.1 0% Batteries, switches/housing, PWB Arsenic 0.0013 < 0.1 0% Doping agents in transistors/PWB Silica 24.8803 15 0% Glass, solid state devices/CRT,PWB Lead Can cause damage to the central and peripheral nervous systems, blood system and kidneys in humans. Effects on the endocrine system have also been observed and its serious negative effects on children’s brain development has been well documented. Lead accumulates in the environment and has high acute and chronic toxic effects on plants, animals and microorganisms. Consumer electronics constitute 40% of lead found in landfills. The main concern in regard to the presence of lead in landfills is the potential for the lead to leach and contaminate drinking water supplies. The main applications of lead in computers are: Soldering of printed circuit boards and other electronic components Glass panels in computer monitors (cathode ray tubes) Between 1997 and 2004, over 315 million computers will become obsolete is the USA. This adds up to about 1.2 billion pounds of lead! Cadmium Compounds are classified as toxic with a possible risk of irreversible effects on human health. Cadmium and cadmium compounds accumulate in the human body,in particular in kidneys. Cadmium is adsorbed through respiration but is also taken up with food. Due to the long half-life (30 years), cadmium can easily be accumulated in amounts that cause symptoms of poisoning. Cadmium shows a danger of cumulative effects in the environment due to its acute and chronic toxicity. In electrical and electronic equipment, cadmium occurs in certain components such as SMD chip resistors, infrared detectors and semiconductors. Older types of cathode ray tubes contain cadmium. Furthermore, cadmium is used as a plastic stabilizer. Between 1997 to 2004 over 315 million computers will become obsolete and this represents almost 2 million pounds of cadmium content. When inorganic mercury spreads out in the water, it is transformed to methylated mercury in the bottom sediments. Methylated mercury easily accumulates in living organisms and concentrates through the food chain particularly via fish. Methylated mercury causes chronic damage to the brain. It is estimated that 22 % of the yearly world consumption of mercury is used in electrical and electronic equipment. It is basically used in thermostats, (position) sensors, relays and switches (e.g. on printed circuit boards and in measuring equipment) and discharge lamps. Furthermore, it is used in medical equipment, data transmission, telecommunications, and mobile phones. Mercury is also used in batteries, switches/housing, and printed wiring boards. Although this amount is small for any single component, 315 million obsolete computers by the year 2004 represent more than 400,000 pounds of mercury in total. Hexavalent Chromium (Chromium VI) is the nasty agent made 'infamous' in the 2000 movie "Erin Brokovich". A true story about a 'vampy' paralegal responsible for winning a $333 million lawsuit against a utility company inadvertently maiming nearby citizens with its improper disposal of this chemical. Some manufacturers still apply this substance as corrosion protection of untreated and galvanized steel plates and as a decorative and hardener for steel housing. Chromium VI can easily pass through membranes of cells and is easily absorbed producing various toxic effects within the cells. It causes strong allergic reactions even in small concentrations. Asthmatic bronchitis is another allergic reaction linked to chromium VI. Chromium VI may also cause DNA damage. In addition, Hexavalent chromium compounds are toxic for the environment. It is well documented that contaminated wastes can leach from landfills. Incineration results in the generation of fly ash from which chromium is leachable, and there is widespread agreement among scientists that wastes containing chromium should not be incinerated. Of the more than 315 million computers destined to become obsolete between 1997 and 2004, about 1.2 million pounds of Hexavalent chromium will be present. It should be noted that Chromium 6's toxicity is a matter of HEATED debate within the scientific community. While everyone agrees that extremely high levels of the substance can cause lung cancer when ingested via air. There is evidence to support that ingestion through drinking water causes no type of damage whatsoever. Based on the calculation that more than 315 million computers will become obsolete between 1997 and 2004 and that plastics make up 13.8 pounds per computer on average, there will be more than 4 billion pounds of plastic present in this computer waste. An analysis commissioned by the Microelectronics and Computer Technology Corporation (MCC) estimated that the total electronics plastic scrap amounted to more than 1 billion pounds per year (580,000 tons per year). This same study estimated that the largest volume of plastics used in electronics manufacturing (at 26%) was polyvinyl chloride (PVC), which creates more environmental and health hazards than most other type of plastic (see below). 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 computer scrap that continues to grow – potentially up to 250 million pounds per year. The use of PVC in computers has been mainly used in cabling and computer housings, although most computer moldings are now being made of ABS plastic. PVC cabling is used for its fire retardant properties, but there are concerns that once alight, fumes from PVC cabling can be a major contributor to fatalities and hence there are pressures to switch to alternatives for safety reasons. Such alternatives are low-density polyethylene and thermoplastic olefins. PVC is a difficult plastic to recycle and it contaminates other plastics in the recycling process. Of more importance, however, the production and burning of PVC products generates dioxins and furans. This plastic commonly used in packaging and household products is a major cause of dioxin formation in open burning and garbage incinerators. Hospitals are now beginning to phase out the use of PVC products such as disposal gloves and IV bags because of the dangers of incinerating these products. Many local authorities in Europe have PVC-free policies for municipal buildings, pipes, wallpaper, flooring, windows and packaging. Recent concerns about the use of softeners in PVC plastic toys leaching out into children’s mouths have lead to further restrictions on PVC. Brominated flame-retardants Are a class of brominated chemicals commonly used in electronic products as a means for reducing flammability. In computers, 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 TV sets and in domestic kitchen appliances. Various scientific observations indicate that Polybrominated Diphenylethers (PBDE) might act as endocrine disrupters.. Research has revealed that levels of PBDEs in human breast milk are doubling every five years and this has prompted concern because of the effect of these chemicals in young animals. A recent study found that newborn mice fed PBDEs show abnormal behavior when placed in new surroundings. Normal mice become very active when first transferred to a new environment but gradually slow down as they complete their explorations. However, treated mice were less active at first but became more active after being in new surroundings for an hour. Researchers concluded that exposure to the chemicals in early life could induce neurotoxic effects similar to those caused by other toxic substances such as PCBs and some pesticides. Other studies have shown PBDE, like many halogenated organics, reduces levels of the hormone thyroxin in exposed animals and have been shown to cross the blood brain barrier in the developing fetus. Thyroid is an essential hormone needed to regulate the normal development of all animal species, including humans. Researchers in the US found exposure to Polybrominated Biphenyls (PBBs) may cause an increased risk of cancer of the digestive and lymph systems. The study looked at cancer incidence in individuals exposed to PBBs after a 1973 food contamination incident in Michigan. About a ton of PBB fire retardant was added to cattle feed in error and contamination spread through the animal and human food chain. Some nine million people were affected. A study published in 1998 found that the group with the highest exposure was 23 times more likely to develop digestive cancers, including stomach, pancreas and liver cancers. Preliminary results also found a 49-fold increase in lymph cancers. The presence of PBBs in Arctic seal samples indicates a wide geographical distribution. The principal known routes of PBBs from point sources into the aquatic environment are PBBs plant areas and waste dumps. PBBs are almost insoluble in water and are primarily found in sediments of polluted lakes and rivers. PBBs have been found to be 200 times more soluble in a landfill leachate than in distilled water, which may result in a wider distribution in the environment. Once they have been released into the environment, they can reach the food chain, where they are concentrated. PBBs have been detected in fish from several regions. Ingestion of fish is a source of PBB transfer to mammals and birds. Neither uptake nor degradation of PBBs by plants has been recorded. In contrast, PBBs are easily absorbed by animals. The presence of polybrominated flame-retardants in plastic makes recycling dangerous and difficult. It has been shown that Polybrominated Diphenylethers (PBDEs) form the toxic polybrominated dibenzo furans (PBDF) and polybrominated dibenzo dioxins (PBDD) during the extruding process, which is part of the plastic recycling process. As a consequence, the German chemical industry stopped the production of these chemicals in 1986. In addition, high concentrations of PBDEs have been found in the blood of workers in recycling plants. A recent Swedish study found that when computers, fax machines or other electronic equipment are recycled, dust containing toxic flame-retardants is spread in the air. Workers at dismantling facilities had 70 times the level of one form of flame retardant than are found in hospital cleaners. Because of their common presence in air, clerks working full-time at computer screens also had levels of flame-retardants in their blood – slightly higher than for cleaners. Humans may directly absorb PBDEs when they are emitted from electronic circuit boards and plastic computer and TV cabinets.