What’s the Deal with Mercury Switches?

Mercury is a heavy, silver-white metal; it is also known as Quicksilver.  It is the only metal that is liquid at standard temperature and pressure.  It does not conduct heat well but it does conduct electricity.  Due to its liquid form and ability to conduct electricity, it was widely used in the past in positional, electrical switches.  Mercury is highly toxic and effects plants, animals and humans that are exposed to it.  Improper mercury disposal techniques have led to widespread environmental contamination.  Environmental regulations exist today in hopes of reducing the amount of mercury that is released to the environment.  Mercury contamination is regulated under the Clean Air Act, the Clean Water Act, the Resource Conservation and Recovery Act and the Safe Drinking Water Act. 

Mercury switches or mercury tilt switches are electrical switches that interrupt the flow of current based on alignment or physical position.  The switch is made of a sealed glass or metal pellet that contains a drop of mercury.  The pellet has one or more sets of electrical contacts that when in contact with the mercury form a completed circuit.  Based on the position of the switch, gravity or inertia pulls the mercury and closes or opens the circuit.  When the switch is tilted the opposite direction, the circuit is either opened or closed.  Mercury switches were widely used in the automotive industry for trunk lid lights, open door indicators and anti-lock braking systems, but due to the harmful effects mercury has on the environment their use was discontinued in all American made cars in 2003.

The National Vehicle Mercury Switch Removal Program (NVMSRP) was created to address the growing mercury contamination in our rivers, lakes and oceans as a result of improper mercury switch disposal techniques.  If mercury switches are not removed prior to crushing, shredding and steel melting processes the mercury may be emitted to the air as mercury vapor where it will eventually return to earth as rainfall.  It can also enter surface water bodies through direct runoff via storm water. 

Mercury biomagnifies as it moves up the food chain meaning that a small fish may have low mercury concentrations in its body.  When that fish is eaten by a larger fish the concentration of mercury amasses in the predator’s body.  This process continues up the food chain and concentrations increase over time.  Humans are at the top of the food chain and as such are very susceptible to mercury exposure.  Mercury is a toxin that affects the nervous system and brain; it is most harmful to developing fetuses and young children. 

Occupational exposure studies show that an eight hour exposure to mercury vapor can cause profound central nervous system effects and psychotic reactions to include delirium, hallucinations and suicidal tendency.  Continued exposure can lead to insomnia and body tremors that can escalate into violent muscle spasms.  Long-term exposure to mercury vapor can result in death.  One of the worst recorded industrial disasters in history occurred in Minamata Bay, Japan as a result of illegal dumping of mercury.  A fertilizer and petrochemical company polluted the Minamata Bay from the 1930s through the 1960s.  The mercury accumulated in the shellfish in the bay which were the main food source for the village surrounding it.  Over 3,000 people suffered deformities, mercury poisoning and death as a result of consuming mercury contaminated shellfish.                

The NVMSRP estimates that there are 67 million automotive mercury switches available for recovery in the United States.  Indiana state law requires each automotive recycler to remove all mercury switches from vehicles when they are received.  The Indiana Department of Environmental Management (IDEM) will pay $3.00 for each mercury switch and $5.00 for an ABS Sensor if the switches are recycled through End of Life Vehicle Solutions (ELVS).  You must register with ELVS and IDEM by filling out a Vendor Information Form and a Claim for Payment for Mercury Switches Form from ELVS in order to receive payment when you submit switches for disposal. 

ELVS provides a free collection bucket to accumulate switches in along with documentation, free shipping labels, removal instructions and they pay for the final disposal costs of the switches.  Each bucket comes with a sticker that states that the bucket’s contents are Universal Waste.  Universal Waste is hazardous waste that can be managed with reduced regulation but on-site requirements.  It is important to annotate on the sticker that the contents are ‘Mercury Containing Equipment’, the start date for switch accumulation and yard address.  Universal Waste can only be stored for one year.  At least two weeks before the 1-year anniversary of your bucket start date call ELVS to request a replacement bucket and mail the filled bucket to ELVS via UPS.  Some of the switches are encased in metal, others are made of glass.  It is important to leave the glass switches in their housing to prevent breakage.  The metal pellets can be removed from their housing for storage.  Ensure that the switches are stored inside the plastic bucket liner and the bucket lid is sealed when not in use.  A 3.5 gallon bucket will hold up to 450 mercury switches. 

A mercury spill can be cleaned up relatively easily if the proper supplies are available.  A mercury spill in excess of the size of a quarter should be reported.  All spills should be cleaned up.  At a minimum you should contact your local Emergency Planning Committee (EPC).  It is very important to identify your local EPC ahead of time and to display the number in the area where mercury is handled.  The local EPC will guide you on your next step or refer you to someone that can help you.

It is important that you clean a mercury spill up properly and contact the appropriate agency as soon as you discover the spill.  You will not get in trouble if it is handled correctly, accidents happen.  If you do not clean up the spill immediately and effectively you will create a very significant exposure problem for yourself, your personnel, your customers and our environment.  Mercury can be tracked or disseminated by foot traffic, floor sweeping and other activities.  A clean up is much easier and more cost-effective if the material to be cleaned up is not spread out.  Mercury can disperse and contaminate more area and media such as soil, carpeting and surfaces requiring a more extensive and expensive clean up in the future.          

If the spill is smaller than a quarter the steps to clean up the spill are as follows:

·       Combine smaller droplets into a single larger pool on a hard surface; prevent it from entering drains, cracks or crevices 

·       All persons that are not involved in the cleanup should leave the area ensuring that there is no mercury on clothing or shoes 

·       Close doors leading to indoor areas and turn off all heating and ventilating systems that lead to indoor areas; open doors and windows that lead to the outdoors to ventilate harmful vapors 

·       Do not use a vacuum cleaner or broom to move or contain the mercury because the liquid will be dispersed or vaporized 

·       Use the chemicals in a mercury spill kit to coat and form an amalgam with the mercury

·       Place mercury contaminated clothing and other items in a plastic trash bag and wash your hands

·       Contact your local Emergency Planning Committee for guidance on where to properly dispose of the mercury

The NVMSRP is a good program.  The money that IDEM is willing to pay per mercury switch offsets the cost to recover them, which is a good thing.  While mercury is extremely toxic and harmful for our global environment; it is also acutely hazardous to yourself and your personnel.  Each mercury switch that is placed in a bucket and shipped to ELVS is one that will not enter the environment and does not have the potential to harm someone down the road.  This is a program that we should support and take part in. 

This article was originally featured in the February/March 2011 issue of ARI Magazine

Sara HamidovicComment