Table of Contents
- What Is Bis(2-Ethylhexyl) Phthalate?
- Bis(2-Ethylhexyl) Phthalate in Electronics
- Toxicity of Bis(2-Ethylhexyl) Phthalate
- RoHS: Restriction of Hazardous Substances
- Alternatives to Bis(2-Ethylhexyl) Phthalate
- DEHP-Limiting Legislation
- Other Phthalates Restricted by RoHS
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.
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.