Bis(2-Ethylhexyl) phthalate (DEHP) is a chemical used in the manufacturing of many electronic devices. The use of DEHP and three other phthalates is restricted by the European Union’s RoHS directive due to their high toxicity.

What Is Bis(2-Ethylhexyl) Phthalate?

DEHP stands for di-2-ethylhexyl phthalate, and is also known as bis(2-ethylhexyl) or dioctyl phthalate (DOP). Its chemical formula is C₂₄H₃₈O₄. 

DEHP is an industrially-produced phthalate, a class of chemicals that are used to make plastics stronger and more durable. Phthalates may also be used to help dissolve other materials.

DEHP was first produced in 1939 in the United States, and production of DEHP hit a high in 1976, when the U.S. produced 180,000 metric tons. While its use has lessened due to concerns about its toxicity, DEHP was the most popular phthalate to use as a plasticizer, and historically made up about fifty percent of all phthalate plasticizers used.

Bis(2-Ethylhexyl) Phthalate in Electronics

DEHP is primarily used as a plasticizer, a substance that makes plastic more flexible. Plastics can contain anywhere from one to forty percent DEHP. 

DEHP works as a plasticizer to make polyvinyl chloride (PVC) more flexible. PVC containing DEHP is often used in the plastic sheathing around wires and cables in electronic equipment, or in some cases, to make plastic casings around electronic components.

DEHP is also used (not as a plasticizer) in capacitors, devices that store electrical energy. Capacitors are used in electronic circuits to allow alternating current (AC) to pass while blocking direct current (DC). The DEHP works as a dielectric fluid to prevent rapid electric discharges and can help remove excess heat in an electronic device.

Toxicity of Bis(2-Ethylhexyl) Phthalate

DEHP exposure can occur in a number of ways. DEHP enters the environment through releases from factories that produce DEHP or products that use DEHP. Additionally, when products containing DEHP are disposed of, the chemical can leach out of plastic over time. DEHP has been found in groundwater near landfills and waste disposal sites.

It is also possible to be exposed to DEHP by touching plastics that contain the chemical, although exposure through this method is likely too low to cause health problems. The United States Center for Disease Control (CDC) performed a study that found that although DEHP is detectable in the general population, it is unlikely to cause harmful health effects at those levels. However, more research is needed on the health impacts of low-level DEHP exposure.

DEHP may cause serious health effects in workers who produce DEHP or DEHP-containing products, or in waste-disposal and recycling workers. Negative health impacts of DEHP may include disruption of the endocrine system in males, disruption of placental growth, obesity, and cancer. Most research has been performed only on mice and rats, so more research is necessary to confirm these effects in humans.

RoHS: Restriction of Hazardous Substances

RoHS stands for Restriction of Hazardous Substances. The RoHS directive, issued in the European Union, restricts the use of several hazardous materials in electronic and electrical equipment (EEE). All EEE products sold in the EU must comply with RoHS.

RoHS restricts the use of ten hazardous substances in electronics, including DEHP and three other phthalates (bolded below). Electronic devices may only contain these substances in amounts lower than 1000 ppm. The allowable amount for cadmium is 100 ppm.

The materials include:

• Cadmium (Cd)
• Mercury (Hg)
• Lead (Pb)
• Hexavalent Chromium (Cr VI)
• Polybrominated Biphenyls (PBB)
• Polybrominated Diphenyl Ethers (PBDE)
• Bis(2-Ethylhexyl) phthalate (DEHP)
• Benzyl butyl phthalate (BBP)
• Dibutyl phthalate (DBP)
• Diisobutyl phthalate (DIBP)

These phthalates were not included in the original 2002 RoHS directive, but were added in 2015 by Directive EU 2015/863, also known as RoHS 3. 

Any manufacturer, importer, or distributor of electronic and electrical equipment (EEE) sold on the EU market must be compliant with RoHS. 

EEE regulated under RoHS includes a wide variety of electronic products separated into eleven categories, ranging from large household appliances to medical devices. The eleventh category is all-encompassing, as it includes any EEE not covered in the previous ten categories. 

Read more about how to ensure compliance with RoHS: What is ‘RoHS Compliant’?

Alternatives to Bis(2-Ethylhexyl) Phthalate

RoHS works to reduce the risk of DEHP exposure by restricting its use in electronic devices.

As a result of RoHS legislation and increasing concern about the toxicity of DEHP, many electronics manufacturers no longer use it. RoHS pushes industry to innovate substitutions for restricted hazardous materials. As a result, manufacturers and researchers are searching for safer alternatives to DEHP. However, it is difficult to find perfect alternatives because DEHP is a low-cost and widely available chemical.

Several possible plasticizer alternatives to DEHP include di-2-ethylhexyl-terephtalate (DEHT), trioctyl trimellitate (TOTM), and 1,2-Cyclohexane dicarboxylic acid diisononyl ester (DINCH). However, implementation of these alternatives to replace DEHP requires redesign of many products and manufacturing processes.

DEHP-Limiting Legislation

EU RoHS is the main legislation that limits DEHP in electronics, but similar RoHS rules that limit the chemical have been adopted by other countries including China and the UAE.

The use of DEHP has been regulated in industries other than electronics as well. In 2004, the EU banned the use of DEHP in children’s toys. In 2008, the EU added DEHP to its list of Substances of Very High Concern (SVHC) regulated under the REACH regulation, which regulates the use of chemicals in a wide variety of products. Read more: What’s the Difference Between RoHS, REACH, and WEEE?

Additionally, California classified DEHP under Proposition 65 as a “chemical known to the State of California to cause cancer and birth defects or other reproductive harm.”

Lastly, the U.S. Environmental Protection Agency (EPA) has passed a variety of environmental regulations, such as the Clean Water Act and the Clean Air Act, that list phthalates as toxic pollutants and create limits for the amount of DEHP that can be safely present in the environment.

Other Phthalates Restricted by RoHS

While DEHP is the most commonly used phthalate plasticizer, RoHS also restricts the use of three other phthalates:

• Benzyl butyl phthalate (BBP)
• Dibutyl phthalate (DBP)
• Diisobutyl phthalate (DIBP)

These chemicals have similar uses to DEHP, and are similarly toxic.

Benzyl Butyl Phthalate (BBP)

BBP is mainly used as a plasticizer in PVC or vinyl foams. It can be absorbed by the body through the skin (dermally) or through the mouth (orally). People may be exposed to BBP by touching plastics that contain the chemical, or by working in industries that produce or use BBP.

Occupational exposure to BBP (which causes higher levels of exposure than the average consumer experiences) has been shown to cause multiple myeloma. While more research is needed, BBP may cause a range of other health effects including bronchial obstruction in children and reproductive problems. 

Dibutyl Phthalate (DBP)

DBP is another phthalate commonly used as a plasticizer and also as a solvent to certain dyes. DBP can be absorbed through the skin. DBP can cause health problems when inhaled during production or processing of products containing DBP.

DBP likely disrupts the endocrine system, the system that controls human hormones. When mixed with other toxic chemicals, DBP enhances their effects and can cause developmental defects and reduced sperm counts. In young children exposed to DBP through long-term ingestion (for example, if a plastic toy with DBP is chewed on for a long time), liver and kidney failure is possible.

Diisobutyl Phthalate (DIBP)

DIBP is a plasticizer used in a variety of different plastics that is often used interchangeably with DBP, although it has a lower density and freezing point than DBP. DIBP is also quite stable in high heat and light.

Because the chemical coagulates well, it is often used as a gelled material in inks and adhesives. DIBP is most commonly used in electronics as a hydraulic fluid in capacitors.

There is very little research on the health effects of DIBP in humans, but studies in animals show DIBP can cause liver problems, developmental effects in children, reproductive problems, and reduced weight among other problems. DIBP exposure in high doses such as those experienced by industrial workers may cause more health problems.

Polybrominated Diphenyl Ethers (PBDEs) are a class of chemicals used in the manufacturing of many electronic devices. The use of PBDEs is restricted by the European Union’s RoHS directive due to their high toxicity.

Properties of Polybrominated Diphenyl Ethers

PBDEs are a manmade class of chemicals not found in nature. PDBEs are an organobromine compound, a compound that contains carbon bonded to the element bromine.

There are three types of commercial mixtures of PBDEs: pentabromodiphenyl ether (pentaBDE), octabromodiphenyl ether (octaBDE) and decabromodiphenyl ether (decaBDE). While all three mixtures have slightly different physical and chemical properties, all three are considered PBDEs due to their chemical structure. 

The uses of each commercial mixtures differ. For example, penta-BDEs are not commonly used in electronics. DecaBDE is the most commonly used PBDE worldwide. While decaBDE used to be exempt from RoHS regulations, the exemption expired in June 2008. 

When exposed to high temperatures, PBDEs release bromine radicals (a chemically reactive atom), which reduces the rate of combustion and makes it difficult for fire to occur or spread. This property makes PBDEs a popular flame retardant in a variety of consumer products, including electronics, furniture foam, wire insulation, and household textiles like curtains or rugs.

Polybrominated Diphenyl Ethers in Electronics

Most manufacturers of electronic and other consumer products no longer use polybrominated diphenyl ethers due to concerns about the chemical’s toxicity. However, prior to PBDEs’ reduction in use, the chemicals were primarily used as a flame retardant.

One of the main applications for PBDEs in electronics is in printed circuit boards and plastic casings for electronics.

The most common PBDE, deca-BDE, is used in several different types of plastic, such as high impact polystyrene, polyethylene and polypropylene. These materials are used to produce switches, plugs and connectors in electronics, as well as cables and wires.

PBDEs are also added as flame retardants to plastic used in electronics, such as plastic casings around televisions or computers. 

Toxicity of Polybrominated Diphenyl Ethers

While the average consumer may not experience high levels of PBDE exposure, workers who produce PBDEs or who work in waste-processing factories that deal with products coated in PBDEs experience unhealthy levels of exposure to these toxic chemicals.

Ingestion or inhalation of PBDEs can cause negative health effects including disruption of the endocrine system and, in pregnant women, disruption of  prenatal development. Other studies suggest that PBDEs can cause neurotoxicity, diabetes, cancer, and can harm the thyroid, immune system and liver. Research is still ongoing to confirm the health impacts of PBDEs.

RoHS: Restriction of Hazardous Substances

RoHS stands for Restriction of Hazardous Substances. The RoHS directive, issued in the European Union, restricts the use of several hazardous materials in electronic and electrical equipment (EEE). All EEE products sold in the EU must comply with RoHS.

RoHS restricts the use of ten hazardous substances in electronics, including polybrominated biphenyls. Electronic devices may only contain these substances in amounts lower than 1000 ppm. The allowable amount for cadmium is 100 ppm.

The materials include:

• Cadmium (Cd)
• Mercury (Hg)
• Lead (Pb)
• Hexavalent Chromium (Cr VI)
• Polybrominated Biphenyls (PBB)
• Polybrominated Diphenyl Ethers (PBDE)
• Bis(2-Ethylhexyl) phthalate (DEHP)
• Benzyl butyl phthalate (BBP)
• Dibutyl phthalate (DBP)
• Diisobutyl phthalate (DIBP)

Any manufacturer, importer, or distributor of electronic and electrical equipment (EEE) sold on the EU market must be compliant with RoHS. 

EEE regulated under RoHS includes a wide variety of electronic products separated into eleven categories, ranging from large household appliances to medical devices. The eleventh category is all-encompassing, as it includes any EEE not covered in the previous ten categories. 

Read more about how to ensure compliance with RoHS: What is ‘RoHS Compliant’?

Alternatives to Polybrominated Diphenyl Ethers

RoHS works to reduce the risk of PBDE exposure by restricting its use in electronic devices.

As a result of increasing concern about the toxicity of PBDEs, many electronics manufacturers no longer use them. The EU’s RoHS directive reduced the global use of PBDE with its passage in 2002. In 2004, octaBDE and pentaBDE stopped being produced in the U.S. after the only U.S. manufacturer voluntarily stopped production. In 2009, the main U.S. importer of decaBDE, as well as the two main producers, announced that they would stop using decaBDE by 2013. 

RoHS pushes industry to innovate substitutions for restricted hazardous materials. Some researchers argue that flame retardants are simply not worth the health risks, and should therefore not be used at all. However, many manufacturers and scientists are researching and using safer alternative flame retardants. One such alternative is simply using stronger, more naturally flame-resistant metals like silver or titanium, although this would increase the cost of electronic production.

PBDE-Limiting Legislation

EU RoHS is the main legislation that limits polybrominated biphenyls in electronics, but similar RoHS rules that limit PBDEs have been adopted by other countries including China and the UAE.

Legislation passed in other countries bans the use of PBDEs in all products, not just electronics. Several U.S. states have outlawed the use of PBDEs. In California’s bill AB 302, which went into effect January 2008, the use of penta- and octa-BDEs in all products was banned. The state of Washington passed a bill banning all PBDEs in April 2007, and in May 2007, the state of Maine passed a bill that banned the use of decaPBDE.

On an international scale, several types of PBDEs are restricted under the Stockholm Convention on Persistent Organic Pollutants treaty.

Polybrominated Biphenyls (PBBs) are a class of chemicals used in the manufacturing of many electronic devices. The use of PBBs is restricted by the European Union’s RoHS directive due to their high toxicity.

Properties of Polybrominated Biphenyls

PBBs, sometimes referred to as brominated biphenyls or polybromobiphenyls, are a manmade class of chemicals not found in nature. 

There are three types of commercial mixtures of PBB: hexabromobiphenyl (hexaBB), octabromobiphenyl (octaBB) and decabromobiphenyl (decaBB). While all three mixtures have slightly different physical and chemical properties, all three are considered PBBs due to their chemical structure.

PBBs are very stable substances that are resistant to heat, acids, bases, and oxidation. PBBs are soluble in fat but are insoluble in water. PBBs are also quite effective as a flame retardant. These properties made PBBs popular in a variety of consumer products, including electronics.

Polybrominated Biphenyls in Electronics

Most manufacturers of electronic and other consumer products no longer use polybrominated biphenyls due to concerns about the chemical’s toxicity. However, prior to PBBs’ reduction in use, PBBs were primarily used as a flame retardant.

One of the main applications for PBBs in electronics is the  infusion of PBBs into circuit boards. Because circuit boards work to pass electric currents, flame retardants are necessary to reduce the risk of electricity-caused fires.

PBBs are also added as flame retardants to plastic used in electronics, such as plastic casings around televisions or computers.  PBBs are added to these plastic shells late in the manufacturing process without bonding to the plastic, making it easier for PBBs to leach off the plastic later in a product’s life cycle.

Toxicity of Polybrominated Biphenyls

It is currently unclear whether the average consumer experiences exposure to PBBs in electronics, as there is very little data on how these chemicals leach out of electronics. However, it is abundantly clear that workers who produce PBBs or who work in waste-processing factories that deal with products coated in PBBs experience unhealthy levels of exposure to PBBs.

Exposure to high levels of PBBs has been shown to cause hypothyroidism, disruption of the endocrine system, immune system abnormalities, and skin problems. While research is ongoing, multiple governmental agencies have stated that PBB is a likely carcinogen.

The most famous case of health impacts due to PBB exposure is an incident in Michigan in 1973, in which cattle feed supplements were accidentally switched with PBB fire retardants. As a result, PBBs contaminated hundreds of farms and entered the food system, including milk, other dairy products, eggs, and beef. 

Research on the affected Michigan population found increased levels of PBBs in people’s blood, and many people reported negative health impacts (although it is unclear whether those impacts were caused by PBB exposure). Although the health impacts of PBBs have been studied extensively in mice, most research on the human health impacts of PBBs comes from this incident.

RoHS: Restriction of Hazardous Substances

RoHS stands for Restriction of Hazardous Substances. The RoHS directive, issued in the European Union, restricts the use of several hazardous materials in electronic and electrical equipment (EEE). All EEE products sold in the EU must comply with RoHS.

RoHS restricts the use of ten hazardous substances in electronics, including polybrominated biphenyls. Electronic devices may only contain these substances in amounts lower than 1000 ppm. The allowable amount for cadmium is 100 ppm.

The materials include:

• Cadmium (Cd)
• Mercury (Hg)
• Lead (Pb)
• Hexavalent Chromium (Cr VI)
• Polybrominated Biphenyls (PBB)
• Polybrominated Diphenyl Ethers (PBDE)
• Bis(2-Ethylhexyl) phthalate (DEHP)
• Benzyl butyl phthalate (BBP)
• Dibutyl phthalate (DBP)
• Diisobutyl phthalate (DIBP)

Any manufacturer, importer, or distributor of electronic and electrical equipment (EEE) sold on the EU market must be compliant with RoHS. 

EEE regulated under RoHS includes a wide variety of electronic products separated into eleven categories, ranging from large household appliances to medical devices. The eleventh category is all-encompassing, as it includes any EEE not covered in the previous ten categories. 

Read more about how to ensure compliance with RoHS: What is ‘RoHS Compliant’?

Alternatives to Polybrominated Biphenyls

RoHS works to reduce the risk of PBB exposure by restricting its use in electronic devices.

As a result of RoHS legislation, many electronics manufacturers no longer use PBBs. In fact, some U.S. companies stopped using PBBs in the 1970s after the incident in Michigan, and many major electronics manufacturers such as Apple, Dell and Motorola voluntarily stopped using PBBs in the early-mid 2010s.

RoHS pushes industry to innovate substitutions for restricted hazardous materials. Some researchers argue that flame retardants are simply not worth the health risks, and should therefore not be used at all. However, many manufacturers and scientists are researching and using safer alternative flame retardants. One such alternative is simply using stronger, more naturally flame-resistant metals like silver or titanium, although this would increase the cost of electronic production.

PBB-Limiting Legislation

RoHS is the main legislation that limits polybrominated biphenyls in electronics. However, the production and use of PBBs in the United States has decreased significantly since 1976.

Many U.S. states have created programs or rules to regulate the cleanup of historical PBBs in water and soil. For example, states including California, Indiana, Michigan, Mississippi, Nebraska, New York, Texas and West Virginia have adopted screening values for PBB in drinking water, groundwater, and soil. Action must be taken when PBBs are found in water or soil above a certain level established by the state.

Additionally, RoHS rules that limit PBBs have been adopted by other countries including China and the UAE.

Hexavalent chromium is a heavy metal used in the manufacturing of many electronic devices. Hexavalent chromium’s use is limited by the European Union’s RoHS directive due to its high toxicity.

Properties of Hexavalent Chromium

Hexavalent chromium is a heavy metal used in electronics. Heavy metals are metals with relatively high density that are toxic at low concentrations, meaning even a small amount of the metal is toxic.

Chromium is a naturally occurring element found in the earth’s crust, and is most commonly produced in South Africa and Kazakhstan. Hexavalent chromium is a chromium ion (an electrically charged chromium atom) that has the ability to pair with six other atoms. The chemical symbol for hexavalent chromium (sometimes referred to as chromium hexavalent) is Cr(VI). Hexavalent chromium is not found in nature and must be industrially produced.

Chromium exists in other forms as well. However, not only is hexavalent chromium the most common form of chromium in industrial settings, it is also the most toxic.

Hexavalent chromium is popular in electronics manufacturing due to its highly anti-corrosive properties.

Hexavalent Chromium in Electronics

Hexavalent chromium is commonly used in anticorrosive coatings on metal parts in electronics or as a pigment or paint.

The process of protecting metal from corrosion using hexavalent chromium is called chromating or passivation. In passivation, a thin layer of hexavalent chromium salts are added to a metal in an electronic device. For example, many circuit boards are coated with hexavalent chromium.

The process of passivation also helps other coatings like paint and enamel stick better, so many steel and aluminum components have a thin layer of hexavalent chromium added before paint is added on top.

Chromium-coated metal is used in many products and components, including nuts and bolts, electric switches, and antennae.

Hexavalent chromium is also used to produce pigments that coat plastics on switches or fuses, or wire and cable insulation.

Toxicity of Hexavalent Chromium

Hexavalent chromium is carcinogenic and causes a wide range of health problems, particularly in people exposed to the metal in manufacturing.

If hexavalent chromium is inhaled at high levels, it can cause lung cancer, damage to the respiratory tract, and damage to the eyes and skin (dermatitis). Prolonged exposure, such as working in a factory that uses hexavalent chromium to produce anti-corrosive coatings, is especially toxic.

Hexavalent chromium is particularly dangerous because it is very water soluble. When hexavalent chromium comes into contact with a water source, it spreads widely and quickly. Proper disposal of electronics containing hexavalent chromium is important to avoid the breakdown of electronics in landfills that release chromium into soil or water sources.

RoHS: Restriction of Hazardous Substances

RoHS stands for Restriction of Hazardous Substances. The RoHS directive, issued in the European Union, restricts the use of several hazardous materials in electronic and electrical equipment (EEE). All EEE products sold in the EU must comply with RoHS.

RoHS restricts the use of ten hazardous substances in electronics, including hexavalent chromium. Electronic devices may only contain these substances in amounts lower than 1000 ppm. The allowable amount for cadmium is 100 ppm.

The materials include:

• Cadmium (Cd)
• Mercury (Hg)
• Lead (Pb)
• Hexavalent Chromium (Cr VI)
• Polybrominated Biphenyls (PBB)
• Polybrominated Diphenyl Ethers (PBDE)
• Bis(2-Ethylhexyl) phthalate (DEHP)
• Benzyl butyl phthalate (BBP)
• Dibutyl phthalate (DBP)
• Diisobutyl phthalate (DIBP)

Any manufacturer, importer, or distributor of electronic and electrical equipment (EEE) sold on the EU market must be compliant with RoHS. 

EEE regulated under RoHS includes a wide variety of electronic products separated into eleven categories, ranging from large household appliances to medical devices. The eleventh category is all-encompassing, as it includes any EEE not covered in the previous ten categories. 

Read more about how to ensure compliance with RoHS: What is ‘RoHS Compliant’?

RoHS Hexavalent Chromium Exemptions

While alternatives to hexavalent chromium coatings exist and are in the process of being refined, exemptions do exist under RoHS for the use of hexavalent chromium in certain applications and electronic categories. For example, exemptions exist for the use of hexavalent chromium in spare parts for x-ray systems. These exemptions are given a date upon which they expire, and will no longer be exempt from RoHS unless an extension is granted.

Visit the European Chemicals Agency website for a full list of hexavalent chromium exemptions.

Alternatives to Hexavalent Chromium

RoHS works to reduce the risk of hexavalent chromium exposure by limiting the amount of hexavalent chromium used in electronic devices. 

As a result of RoHS legislation, many electronics manufacturers no longer use hexavalent chromium. RoHS pushes industry to innovate substitutions for restricted hazardous materials. Many manufacturers and scientists are researching and using alternatives to hexavalent chromium.

One of the most promising alternatives is another ion of chromium, trivalent chromium. Trivalent chromium is much safer both for human health and the environment. Some manufacturers resist using this alternative due to concerns that the coating it produces is of a lower quality and will increase costs. However, use of trivalent chromium will decrease waste treatment costs that manufacturers must pay when using hexavalent chromium.

Hexavalent Chromium-Limiting Legislation

RoHS is the main legislation that limits hexavalent chromium in electronics. However, other regulations have been passed that focus on occupational exposure to hexavalent chromium.

In the U.S., the Occupational Safety and Health Administration (OSHA) created standards limiting workplace exposure to hexavalent chromium. OSHA’s regulation is one of the strictest hexavalent chromium exposure limits internationally. 

OSHA’s Standard 1910.1026 creates a permissible exposure limit (PEL) to hexavalent cadmium for workers in all non-exempt industries. Employers must ensure that none of their employees are exposed to airborne hexavalent chromium in amounts larger than 5 micrograms per cubic meter of air in an 8 hour work day.

Lead is a heavy metal used in the manufacturing of many electronic devices. Lead’s use is limited by the European Union’s RoHS directive due to its high toxicity.

Properties of Lead

Lead is a heavy metal used in electronics. Heavy metals are metals with relatively high density that are toxic at low concentrations, meaning even a small amount of the metal is toxic. Lead is denser (its particles are more closely packed) than most other materials.

Lead is naturally occurring and is usually found in combination with sulfur in the earth’s crust. The chemical symbol for lead is Pb.

China, the top producer of lead from mines, produced 1.2 million tonnes of lead in 2019, making up almost half of the global total. Australia, Peru, and the U.S. are the other world leaders in production of lead. Each year, more lead is produced from recycled lead-containing materials, rather than from mines.

Characteristics that make lead popular in electronic manufacturing include its softness, its malleability, its ability to be combined with other metals, and the fact that it does not break easily.

Lead in Electronics

Lead is considered one of the most important metals in electronics production. It is most often used in electronics as a compound or alloy with another element.

The main use of lead in electronics is lead soldering. The lead solder attaches two electronic components securely, allowing an electric signal to pass through. For example, lead solder could attach a wire to a circuit board. 

The most common type is tin-lead soldering, which is commonly used in devices where components that are sensitive to heat may crack or melt at high temperatures. When combined with tin, lead has a low melting point, which means it can be worked with at a lower temperature and is less sensitive to variations in temperature. 

Lead is also used in alloys (a mixture) with other metals, such as copper and steel, which expands the use of these metals. Lead alloy in steel is often used in electronic products.

Toxicity of Lead

It is unlikely that the average consumer will experience lead exposure as a result of touching lead solder, as lead solder is used internally in electronics. However, people may be exposed to lead from electronics if a device breaks. More common is lead exposure in workers who manufacture or recycle lead-containing products. Additionally, if lead-containing electronics are put in landfills, as the device breaks down, lead can leach out and contaminate water and soil.

There is no safe exposure level to lead. When lead is swallowed or breathed in, or enters the body another way, it gets stored in blood, which can cause long-term harm.

Lead exposure, particularly in children, can cause damage to the brain and nervous system, lowered IQ, slowed growth, and problems with hearing and speech. Long term exposure in adults can also cause fertility problems, heart disease, and kidney disease.

RoHS: Restriction of Hazardous Substances

RoHS stands for Restriction of Hazardous Substances. The RoHS directive, issued in the European Union, restricts the use of several hazardous materials in electronic and electrical equipment (EEE). All EEE products sold in the EU must comply with RoHS.

RoHS restricts the use of ten hazardous substances in electronics, including lead. Electronic devices may only contain these substances in amounts lower than 1000 ppm. The allowable amount for cadmium is 100 ppm.

The materials include:

• Cadmium (Cd)
• Mercury (Hg)
• Lead (Pb)
• Hexavalent Chromium (Cr VI)
• Polybrominated Biphenyls (PBB)
• Polybrominated Diphenyl Ethers (PBDE)
• Bis(2-Ethylhexyl) phthalate (DEHP)
• Benzyl butyl phthalate (BBP)
• Dibutyl phthalate (DBP)
• Diisobutyl phthalate (DIBP)

Any manufacturer, importer, or distributor of electronic and electrical equipment (EEE) sold on the EU market must be compliant with RoHS. 

EEE regulated under RoHS includes a wide variety of electronic products separated into eleven categories, ranging from large household appliances to medical devices. The eleventh category is all-encompassing, as it includes any EEE not covered in the previous ten categories. 

Read more about how to ensure compliance with RoHS: What is ‘RoHS Compliant’?

RoHS Lead Exemptions

While alternatives to lead soldering exist and are in the process of being refined, exemptions do exist under RoHS for the use of lead in certain applications and electronic categories. These exemptions are given a date upon which they expire, and will no longer be exempt from RoHS unless an extension is granted.

Visit the European Chemicals Agency website for a full list of lead exemptions.

Alternatives to Lead Solder

RoHS works to reduce the risk of lead exposure by limiting the amount of lead used in electronic devices. 

As a result of RoHS legislation, many electronics manufacturers no longer use lead. RoHS pushes industry to innovate substitutions for restricted hazardous materials. Many manufacturers and scientists are researching and using alternatives to lead soldering, including solders containing tin and copper, silver, or other additives.

The most popular lead solder alternative is a solder combining tin, silver and copper known as SAC solder. While SAC solder is now widely used by many in the electronics industry, many changes had to be made in manufacturing processes before the solder could be used. SAC solder has a higher melting point than lead-tin solder, so many products had to be redesigned to withstand higher temperatures.

Another, more experimental alternative to lead solder is the use of ECAs, polymers (materials like silicone) that contain small flakes of conductive metal like silver. These materials stick to circuit boards and the metal works to conduct electricity. The advantage of ECAs is that they can be applied to circuit boards at a much lower temperature than other lead solder alternatives.

Lead-Limiting Legislation

RoHS is the main legislation that limits lead in electronics. However, other legislation has been passed that controls lead in electronic waste (e-waste). 

The United States Environmental Protection Agency (EPA) has several regulations that address the disposal and cleanup of e-waste that contains lead. For example, the EPA has rules for the disposal of cathode ray tubes (CRTs), which contain lead. Visit the EPA website for more information on e-waste regulations.

Mercury is restricted by RoHS, but products that are RoHS compliant may still contain mercury in very small quantities. While RoHS compliant does not mean truly mercury free, RoHS works to limit the risks posed by mercury in electronics.

Mercury: Uses and Dangers

While mercury is widely used in a variety of electronic devices, exposure to mercury can be highly toxic.

Mercury in Electronics

Mercury is a heavy metal commonly used in LCD (liquid crystal display) screens. LCD screens use cold-cathode fluorescent lamps (CCFLs) that contain mercury. CCFLs include fluorescent tubes that work to backlight an LCD TV or monitor screen. The light is produced when electricity is used to excite (add energy to) mercury vapor. The vapor is discharged, which creates a fluorescent coating on the inside of the tube that emits light.

Mercury is also used in some laptop screen shutoffs. In a mercury tilt switch used in some laptops, mercury moves to the other side when the laptop is opened or closed. This shift turns the screen on or off.

Mercury was also used to create switches in televisions that were produced before 1991.

Toxicity of Mercury

Mercury exposure at high levels can cause a host of health impacts, including damage to the brain, heart, lungs, kidneys, central nervous system, and immune system. 

Mercury can be released into the air a number of ways, one of which is through burning of electronic products containing mercury. Mercury can be transported in the air for great distances before it is deposited in soil and water.

While mercury exposure is most common by eating seafood containing mercury, exposure to mercury vapor is also possible if an electronic device containing mercury breaks. For example, if an LCD screen containing cold-cathode fluorescent lamps (which contain mercury) breaks, toxic mercury dust or powder can be released.

Mercury can also cause significant environmental damage. When animals are exposed to mercury at high levels, death and reproductive damage can occur.

Read more about mercury in electronics: Mercury

What is RoHS?

RoHS stands for Restriction of Hazardous Substances. The RoHS directive, issued in the European Union, restricts the use of several hazardous materials in electronic and electrical equipment (EEE). All EEE products sold in the EU must comply with RoHS.

RoHS restricts the use of ten hazardous substances in electronics, including mercury. Electronic devices may only contain these substances in amounts lower than 1000 ppm. The allowable amount for cadmium is 100 ppm.

The materials include:

• Cadmium (Cd)
• Mercury (Hg)
• Lead (Pb)
• Hexavalent Chromium (Cr VI)
• Polybrominated Biphenyls (PBB)
• Polybrominated Diphenyl Ethers (PBDE)
• Bis(2-Ethylhexyl) phthalate (DEHP)
• Benzyl butyl phthalate (BBP)
• Dibutyl phthalate (DBP)
• Diisobutyl phthalate (DIBP)

Any manufacturer, importer, or distributor of electronic and electrical equipment (EEE) sold in the EU market must be compliant with RoHS. Before a product is placed on the market, manufacturers must issue a statement declaring that they have taken the proper steps to ensure RoHS compliance. The product is also marked with a CE marking to show consumers the product is RoHS compliant.

EEE regulated under RoHS includes a wide variety of electronic products separated into eleven categories, ranging from large household appliances to medical devices. The eleventh category is all-encompassing, as it includes any EEE not covered in the previous ten categories. 

Read more about how to ensure compliance with RoHS: What is ‘RoHS Compliant’?

RoHS and Mercury: A Reduction of Risk

RoHS works to reduce the risk of mercury exposure by limiting the amount of mercury used in electronic devices. While a product that is RoHS compliant may still contain mercury, it is present in such small quantities that it poses a lower risk if humans are exposed.

Mercury is most toxic at high levels of exposure. Lower amounts of mercury in electronics means there is a smaller chance of high exposure, both for users if a mercury-containing device breaks, and also for manufacturers of mercury-containing devices.

While mercury may still be used in electronics, it is limited to amounts less than 1000ppm. Ppm stands for “parts per million.” In other words, in an electronic device, mercury may only make up .1% or less by weight. This is a fairly small amount of mercury. 

Because of this limit, some manufacturers no longer use mercury. Additionally, RoHS pushes industry to innovate substitutions for restricted hazardous materials. Many manufacturers and scientists are researching alternatives to mercury, such as sulfur hexafluoride. Much research is still needed to truly achieve a mercury substitute.

Mercury-Limiting Legislation

While there is very little legislation that outright bans mercury to create truly “mercury free” products, there is legislation that controls the use, sale, and importation of mercury. This type of legislation works to create more mercury-free products, as mercury is much less widely available and its use comes with more restrictions.

The clearest example of other mercury-limiting legislation is the United States’ Mercury Export Ban of 2008. This legislation works to make mercury less available on the U.S. and international markets in order to reduce the metal’s use in production. Under the ban, export of mercury is prohibited from the U.S. beginning in January 2013. 

Several U.S. states have enacted similar laws to limit the sale of mercury within their state. For example, in 2005, California enacted Assembly Bill 1415 that prohibits the sale of mercury switches. Another example is Connecticut’s 2006 Public Act 06-181, which requires lamps containing mercury to be labeled and bans the use of mercury in button cell phone batteries. Connecticut also enacted phase-out requirements for products containing mercury.

Mercury in electronics is less of a concern than mercury pollution caused by other industries, and mercury pollution is still a problem. A bill introduced in the U.S. Senate in April 2021 aims to create a national mercury monitoring network.

Cadmium is a heavy metal used in the manufacturing of many electronic devices. Cadmium’s use is limited by the European Union’s RoHS directive due to cadmium’s high toxicity.

Properties of Cadmium

Cadmium is a heavy metal used in electronics. Heavy metals are metals with relatively high density that are toxic at low concentrations, meaning a small amount of the metal is toxic.

Cadmium is naturally occurring and can be found in mineral deposits in the earth’s crust. The chemical symbol for cadmium is Cd and the atomic weight (the total weight of the atoms making up an element) is 112.41 g/mol.

Cadmium is often produced as a byproduct of zinc mining. Around 14,000 tonnes of cadmium are produced annually, mainly by top global suppliers Canada, the U.S., Australia, Mexico, Japan, and Peru.

Characteristics that make cadmium popular in electronic manufacturing include its malleability, high conductivity (ability to conduct electricity), and its resistance to corrosion.

Cadmium in Electronics

Cadmium is used in electronics either as pure cadmium, or, more often, as a compound with another element. 

Rechargeable Batteries

About 75% of cadmium used in manufacturing is used to produce cadmium-nickel rechargeable batteries, used in electronics like cell phones. Batteries are not restricted by the RoHS directive.

Semiconductors

Cadmium selenide, a cadmium compound, is an easily shaped metal that is most often used as semiconductors. Semiconductors can conduct electricity in high heat, but not in low heat. Cadmium is a good semiconductor because it is highly resistant to high temperatures. Semiconductors like cadmium selenide have a conductivity (ability to conduct electricity) that lies in between a conductor (like metal) and a non-conductive insulator (like ceramic). As temperature rises, the conductivity of the semiconductor increases, and the cadmium material can act as a conductor. At low temperatures, the same material blocks the flow of electricity. 

Semiconductors are found in most electronic devices today. Semiconductors have an extremely wide variety of functions, but generally they work to amplify signals in a circuit, convert energy, and pass current in a specific direction.

Plating

Cadmium’s resistance to corrosion makes it a popular metal to use as a protective shield against corrosion in electronics and other metals. Cadmium plating, also known as cad plating, offers low levels of electrical resistance, protects against rust, and can be soldered like tin to attach metals.

Toxicity of Cadmium

When products containing cadmium are not disposed of properly, particularly when they are burned, cadmium is released into the air. While the main source of airborne cadmium is the burning of fossil fuels, disposal of electronic waste can also release cadmium. 

Another route of cadmium exposure is through working in a factory that produces electronics or electronic components containing cadmium. Inhalation of cadmium is an occupational hazard.

Long term exposure to cadmium can cause serious harm to human and animal health.

Exposure to cadmium is most famous for causing a degenerative bone disease, Itai-itai disease. This disease was caused by cadmium poisoning contracted as a result of mining. Cadmium is highly water soluble, and so as mining byproducts that contained cadmium were released into a nearby river, cadmium pollution occurred. Eventually, cadmium was absorbed into crops irrigated by the river, causing widespread disease.

Cadmium can also cause lung irritation, kidney disease, and lung cancer. The U.S. Environmental Protection Agency has classified cadmium as a probable human carcinogen.

Cadmium also has negative environmental impacts. For example, in aquatic organisms, long term exposure to cadmium can cause death and harm to growth, reproduction, immune systems, and development.

RoHS: Restriction of Hazardous Substances

RoHS stands for Restriction of Hazardous Substances. The RoHS directive, issued in the European Union, restricts the use of several hazardous materials in electronic and electrical equipment (EEE). All EEE products sold in the EU must comply with RoHS.

RoHS restricts the use of ten hazardous substances in electronics, including cadmium. Electronic devices may only contain these substances in amounts lower than 1000 ppm. The allowable amount for cadmium is 100 ppm.

The materials include:

• Cadmium (Cd)
• Mercury (Hg)
• Lead (Pb)
• Hexavalent Chromium (Cr VI)
• Polybrominated Biphenyls (PBB)
• Polybrominated Diphenyl Ethers (PBDE)
• Bis(2-Ethylhexyl) phthalate (DEHP)
• Benzyl butyl phthalate (BBP)
• Dibutyl phthalate (DBP)
• Diisobutyl phthalate (DIBP)

Any manufacturer, importer, or distributor of electronic and electrical equipment (EEE) sold on the EU market must be compliant with RoHS. 

EEE regulated under RoHS includes a wide variety of electronic products separated into eleven categories, ranging from large household appliances to medical devices. The eleventh category is all-encompassing, as it includes any EEE not covered in the previous ten categories. 

Read more about how to ensure compliance with RoHS: What is ‘RoHS Compliant’?

RoHS Cadmium Exemptions

While alternatives to cadmium in electronics exist and are in the process of being refined, exemptions do exist under RoHS for the use of cadmium in certain applications and electronic categories.

Visit the European Chemicals Agency website for a full list of cadmium exemptions.

RoHS and Cadmium: A Reduction of Risk

RoHS works to reduce the risk of cadmium exposure by limiting the amount of cadmium used in electronic devices. While a product that is RoHS compliant may still contain cadmium, it is present in such small quantities that it poses a lower risk if humans are exposed.

Cadmium is most toxic at high levels of exposure. Lower amounts of cadmium in electronics means there is a smaller chance of high exposure, both for users if a cadmium-containing device breaks, and also for manufacturers of cadmium-containing devices.

While cadmium may still be used in electronics, it is limited to amounts less than 100ppm. Ppm stands for “parts per million.” In other words, in an electronic device, cadmium may only make up .01% or less by weight. This is a fairly small amount of cadmium. 

Because of this limit, some manufacturers no longer use cadmium. Additionally, RoHS pushes industry to innovate substitutions for restricted hazardous materials. Many manufacturers and scientists are researching alternatives to cadmium, such as zinc alloys or gold.

Cadmium-Limiting Legislation

RoHS is the main legislation that limits cadmium in electronics. However, other regulations exist that limit the use of cadmium in consumer products. For example, the United States ASTM Standard F 963-17: Requirements Standard Consumer Safety Specification for Toy Safety requires surface coatings used in toys to contain less than 75ppm cadmium. 

In addition to its RoHS legislation, the state of California passed Proposition 65, which limits the use of cadmium in certain products, including several electronic devices.