Among all metal elements, cadmium is one of the most harmful elements to human health. Cadmium is harmful to human tissues and organs in many ways, mainly to kidneys and liver.
The second harmful substance-lead
Lead is a heavy metal element harmful to the nervous system. Severe lead poisoning can lead to stunting and even death of children.
The Third Harmful Substance-Mercury
Mercury poisoning can lead to obvious memory loss, inattention and general weakness.
The fourth harmful substance-hexavalent chromium
Chromium can cause various inflammations and is also a carcinogen.
The fifth and sixth kinds of harmful substances-PBB&; PBDE
PBB & ampPBDE can cause thyroid hormone disorder and fetal malformation.
I. Use of cadmium in electronic products:
Cadmium metal or powder can be used as cathode electrode material of nickel cadmium (NiCd) battery. It can also be used as a coating in electrolytic deposition, vacuum deposition or mechanical deposition together with iron, steel, aluminum-based materials, titanium-based alloys or other non-ferrous alloys. In addition, it is also used as an alloying element for low melting point hard welding, soft welding and other special alloys.
Harm of cadmium:
Since 1950 to 1960, the adverse effects of cadmium on human health (pain) have been widely discussed. The most significant effect is that workers exposed to high concentrations of cadmium-containing smoke or suspended particles will affect the kidneys and respiratory system. The most thoroughly studied effect on human health is renal failure, which is caused by long-term high-dose exposure. Therefore, most developed countries have formulated occupational exposure standards for cadmium, which can protect the normal working life of human body for 40 to 45 years in the atmosphere of 2 mg/m3 to 50 mg/m3.
Prohibited scope:
In order to reduce workers' exposure to cadmium and ensure that the exposure and risks caused by cadmium-containing products to consumers are minimized, in European countries, cadmium and some cadmium-containing products have obtained EC Directives 76/769/EEC, 9 1/338/EEC, 91157/EEC and/KLOC-. Before the EC restricted products such as pigments, stabilizers and paints, Sweden, Denmark, the Netherlands, Switzerland, Austria and Norway also controlled products containing cadmium (9 1/338/EEC). But at present, there are no other countries in the world to control cadmium-containing products except EU countries.
RoHS:
Since 2008, the electrical and electronic equipment specified in this directive shall not contain cadmium.
Except for the following
Cadmium oxide on the surface of selenium photocell
Passivated metal cadmium is used for anticorrosion of special articles.
Heavy metals such as lead, cadmium and mercury are used in hollow cathode tubes and other heavy metal measuring equipment in atomic absorption spectrometry.
TCO' 0 1- mobile phone:
The cadmium content in mobile phones should not be greater than 5ppm.
Two. The use of lead in electronic products;
Battery, solder, alloy elements of mechanical metal, printed circuit board and related parts, white-baked light bulb, plumb hammer.
Harm of lead:
Metal lead process may produce lead compounds, which are all dangerous substances and have different toxic effects. In human body, lead can affect the central nervous system and kidneys. The environmental toxicity of lead to some organisms has been generally confirmed. Blood lead concentration reaches 10? Above g/dl, it will produce sensitive biochemical effects. If long-term exposure makes the blood lead concentration exceed 60~70? G/dl can cause clinical lead poisoning. The surface of lead reacts easily in air, soil and water to form a protective and insoluble inorganic lead compound. These inorganic compounds have low bioavailability and are usually absorbed by terrestrial plants and animals only at high concentrations. However, lead has no biomagnification effect in terrestrial or aquatic food chains.
Prohibited scope:
Lead recovered from waste electrical and electronic equipment is exactly the same as that recovered from original minerals, so it should be possible to limit lead in a closed cycle. However, at present, the lead recovery rate of waste electrical and electronic equipment is limited by the waste recovery rate, not a technical obstacle. Based on the toxicity of lead compounds to human body and environment, it is necessary to restrict the production, use, recovery and disposal of lead by legislation. The allowable level of human exposure must also be specified. Generally speaking, there is a lot of knowledge about the risks of using lead. At present, there is extensive legislation, such as petroleum products and water pipes, to ensure human health and environmental protection. Therefore, in the past 20 years, lead poisoning incidents in most countries have decreased sharply, and the lead content in the environment is usually far below the recommended value. In addition, lead can be completely recovered and can be used for electrical appliances and electronic equipment forever.
RoHS:
Since 2008, the electrical and electronic equipment specified in the directive shall not contain lead.
Except for the following
Heavy metal lead is used in radiation or radiation protection equipment.
Lead is used in cathode ray tube glass, light bulbs and fluorescent tubes.
The maximum lead content of steel, aluminum and copper is 0.3%, 0.4% and 4% respectively.
Lead is used in ceramic parts of electronic equipment.
Heavy metals such as lead, cadmium and mercury are used in hollow cathode tubes of atomic absorption spectrometers and other heavy metal measuring equipment.
The lead content in batteries, paints, coatings, wires and plastics of mobile phones shall not be greater than 10ppm.
Three. Use of mercury in electronic products;
Measuring and control instruments, batteries, light sources and electrical equipment, dentistry, chlorine production equipment (amalgam electrolysis process).
Hazards of mercury:
Mercury is classified as a dangerous substance, inhaled poison and has bioaccumulation effect. Mercury is also highly toxic to aquatic organisms. The impact on human body mainly affects the central nervous system and kidney system. Under some environmental conditions, it has the potential threat of transforming into organic mercury, which leads to its enhanced toxicity characteristics. Mercury has remarkable potential: bioaccumulation and biomagnification. This conclusion has been confirmed in the environmental toxic effects of various organisms. It is also easy to transport in the atmosphere for a long distance, so wet deposition is one of the main steps of mercury cycle.
Prohibited scope:
In order to minimize mercury exposure, several measures have been proposed. Such as electrical equipment (especially using reduced mercury), try to reduce the standard value of mercury content in electric lamps or switches or use substitute substances. It is estimated that 1 1% of the total mercury artificially released into the atmosphere in Europe was caused by lighting and electrical equipment. Improving the energy efficiency of mercury-containing lamps can reduce mercury emissions.
RoHS:
Since 2008, the electrical and electronic equipment controlled by this directive must not contain mercury.
Except for the following
The content of heavy metal mercury in small fluorescent bulbs shall not exceed 5mg/ bulb.
The content of heavy metal mercury in straight fluorescent bulbs shall not exceed 10mg/ bulb.
Heavy metal mercury in laboratory equipment
Heavy metals such as lead, cadmium and mercury are used in hollow cathode tubes of atomic absorption spectrometers and other heavy metal measuring equipment.
TCO'0 1- mobile phone:
The mercury content in mobile phones should not be greater than 2ppm.
Four. The use of hexavalent chromium in electronic products;
Hexavalent chromium is often used as chromic acid in electrochemical industry. In addition, it is also used as a colorant in pigments (lead chromate) and a preservative in cooling water circulation systems (sodium dichromate), such as heat pumps, industrial freezers and refrigerator heat exchangers.
Harm of hexavalent chromium;
Hexavalent chromium is an ingestive poison/inhalation extreme poison, and skin contact may cause allergies; It is more likely to cause genetic defects, and inhalation may cause cancer, which is a lasting danger to the environment. But these are the characteristics of hexavalent chromium, while metallic chromium, trivalent chromium or tetravalent chromium have no such toxicity.
Prohibited scope:
In the European Union, hexavalent chromium, which can cause cancer or mutation, is not allowed to be sold publicly. However, chromic acid is reduced to CrO state (zero valence) in electrochemical industry and CrO2 in adhesive tape industry. Therefore, it will not affect the electrochemical industry or the tape industry.
RoHS:
Since 2008, the electrical and electronic equipment specified in this directive shall not contain hexavalent chromium.
Except for the following
Hexavalent chromium corrosion inhibitor is used in the cooling system of absorption refrigerator.
TCO'0 1- mobile phone:
At present, there is no regulatory standard for hexavalent chromium.
Application of bromine flame retardant in electronic products;
As a flame retardant, it is added to electrical appliances and electronic plastics. Decabromodiphenyl ether and octabromodiphenyl ether are commonly used substances.
Hazards of brominated flame retardants;
Waste plastics in electrical and electronic products may form dioxins or furans (PBDD/F) during uncontrolled thermal process (the temperature is lower than 12000℃). Both are carcinogenic and teratogenic substances. These substances may cause serious and extensive air pollution.
Prohibited scope:
As long as the waste plastics reach the required temperature during incineration, there is no need to take further risk reduction measures for the atmospheric ecosystem. For aquatic, sediment and soil ecosystems, additional ecotoxicity studies are needed to determine potential risks. As for the chemical accumulation caused by food chain and its potential impact on higher food chain species, the current conclusion is: "Under normal circumstances, there is no need to take further risk reduction measures when using and discarding decabromodiphenyl ether and brominated diphenyl ether". Another study reported by WHO (1994) found that "there is no measurable accumulation of brominated diphenyl ethers in meat and skin". In view of the European Parliament's concern about fire safety and reassessment of environmental risks, the European Executive Committee withdrew the proposal in 1993 to restrict the use of polybrominated diphenyl ethers (including decabromodiphenyl ether). The EU risk assessment is also described above. However, in the latest WEEE (Waste Electrical and Electronic Equipment Control Directive), it is planned to restrict the use of this substance through an independent directive (RoHS). Sweden also intends to ban the use of PBDE and decabromodiphenyl ether.
RoHS:
Since 2008, electrical and electronic equipment controlled by this directive must not contain brominated flame retardants.
TCO'0 1- mobile phone: