Electronic waste

Electronic waste or e-waste describes discarded electrical or electronic devices. Used electronics which are destined for reuse, resale, salvage, recycling or disposal are also considered as e-waste. Informal processing of electronic waste in developing countries may cause serious health and pollution problems, as these countries have limited regulatory oversight of e-waste processing.

Electronic scrap components, such as CRTs, may contain contaminants such as, , , or brominated flame retardants. Even in developed countries recycling and disposal of e-waste may involve significant risk to workers and communities and great care must be taken to avoid unsafe exposure in recycling operations and leaking of materials such as heavy metals from landfills and incinerator ashes.

Environmental impact


The processes of dismantling and disposing of electronic waste in the third world lead to a number of environmental impacts as illustrated in the graphic. Liquid and atmospheric releases end up in bodies of water, groundwater, soil, and air and therefore in land and sea animals – both domesticated and wild, in crops eaten by both animals and human, and in drinking water.

One study of environmental effects in Guiyu, China found the following:
 * Airborne dioxins – one type found at 100 times levels previously measured
 * Levels of carcinogens in duck ponds and rice paddies exceeded international standards for agricultural areas and, , , and levels in rice paddies were above international standards
 * Heavy metals found in road dust – lead over 300 times that of a control village’s road dust and copper over 100 times

The environmental impact of the processing of different electronic waste components

Electronic waste substances


Some computer components can be reused in assembling new computer products, while others are reduced to metals that can be reused in applications as varied as construction, flatware, and jewelry.

Substances found in large quantities include epoxy resins, fiberglass, PCBs, PVC (polyvinyl chlorides), thermosetting plastics,, , , , , , and.

Elements found in small amounts include, , and.

Elements found in trace amounts include, , , , , , , , , , , , , , , , , , , , , , , , , , , and.

Almost all electronics contain and  (as solder) and  (as wire and printed circuit board tracks), though the use of lead-free solder is now spreading rapidly. The following are ordinary applications:

Hazardous


There is also evidence of cytotixic and genotoxic effects of some chemicals, which have been shown to inhibit cell proliferation, cause cell membrane lesion, cause DNA single-strand breaks, and elevate Reactive Oxygen Species (RS) levels.
 * The radioactive source in smoke alarms. It is known to be carcinogenic.
 * Found in fluorescent tubes (numerous applications), tilt switches (mechanical doorbells, thermostats), and flat screen monitors. Health effects include sensory impairment, dermatitis, memory loss, and muscle weakness. Exposure in-utero causes fetal deficits in motor function, attention and verbal domains. Environmental effects in animals include death, reduced fertility, and slower growth and development.
 * Found in lead-acid batteries. Health effects include liver damage, kidney damage, heart damage, eye and throat irritation. When released into the environment, it can create sulphuric acid.
 * BFRs: Used as flame retardants in plastics in most electronics. Includes PBBs, PBDE, DecaBDE, OctaBDE, PentaBDE. Health effects include impaired development of the nervous system, thyroid problems, liver problems. Environmental effects: similar effects as in animals as humans. PBBs were banned from 1973 to 1977 on. PCBs were banned during the 1980s.
 * Found in light-sensitive resistors, corrosion-resistant alloys for marine and aviation environments, and nickel-cadmium batteries. The most common form of cadmium is found in Nickel-cadmium rechargeable batteries. These batteries tend to contain between 6 and 18% cadmium. The sale of Nickel-Cadmium batteries has been banned in the European Union except for medical use. When not properly recycled it can leach into the soil, harming microorganisms and disrupting the soil ecosystem. Exposure is caused by proximity to hazardous waste sites and factories and workers in the metal refining industry. The inhalation of cadmium can cause severe damage to the lungs and is also known to cause kidney damage. Cadmium is also associated with deficits in cognition, learning, behavior, and neuromotor skills in children.
 * Solder, CRT monitor glass, lead-acid batteries, some formulations of PVC. A typical 15-inch cathode ray tube may contain 1.5 pounds of lead, but other CRTs have been estimated as having up to 8 pounds of lead. Adverse effects of lead exposure include impaired cognitive function, behavioral disturbances, attention deficits, hyperactivity, conduct problems and lower IQ
 * Beryllium oxide: Filler in some thermal interface materials such as thermal grease used on heatsinks for CPUs and power transistors, magnetrons, X-ray-transparent ceramic windows, heat transfer fins in vacuum tubes, and gas lasers.
 * Perfluorooctanoic acid (PFOA): Found in Non-stick cookware (PTFE), used as an antistatic additive in industrial applications, and found in electronics. PFOAs are formed synthetically through environmental degradation and, in mice, after oral uptake.  Studies in mice have found the following health effects: Hepatotoxicity, developmental toxicity, immunotoxicity, hormonal effects and carcinogenic effects.  Studies have found increased maternal PFOA levels to be associated with an increased risk of spontaneous abortion (miscarriage) and stillbirth.  Increased maternal levels of PFOA are also associated with decreases in mean gestational age (preterm birth), mean birth weight (low birth weight), mean birth length (small for gestational age), and mean APGAR score.
 * Hexavalent chromium: A known carcinogen after occupational inhalation exposure.
 * DNA breaks can increase the likelihood of developing cancer (if the damage is to a tumor suppressor gene)
 * DNA damages are a special problem in non-dividing or slowly dividing cells, where unrepaired damages will tend to accumulate over time. On the other hand, in rapidly dividing cells, unrepaired DNA damages that do not kill the cell by blocking replication will tend to cause replication errors and thus mutation
 * Elevated Reactive Oxygen Species (ROS) levels can cause damage to cell structures (oxidative stress)

Generally non-hazardous



 * nearly all electronic goods using more than a few watts of power (heatsinks), electrolytic capacitors.
 * copper wire, printed circuit board tracks, component leads.
 * 1950s–1960s transistorized electronics (bipolar junction transistors).
 * connector plating, primarily in computer equipment.
 * steel chassis, cases, and fixings.
 * lithium-ion batteries.
 * nickel-cadmium batteries.
 * glass, transistors, ICs, printed circuit boards.
 * solder, coatings on component leads.
 * plating for steel parts.