Understanding Restriction of Hazardous Substances in Electronics
Table of Contents
- Understanding Restriction of Hazardous Substances in Electronics
- Mercury: Uses and Dangers
- What is RoHS?
- RoHS and Mercury: A Reduction of Risk
- Mercury-Limiting Legislation
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.
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.