There are two categories of batteries that currently contain mercury in the United States: mercuric-oxide and button cell. Mercuric-oxide batteries are not available to the public, but button-cell batteries are widely used by consumers.
Mercuric-oxide batteries were once widely used in hearing aids but are now prohibited under federal law. Larger mercuric-oxide batteries, which look like 9V or fat AA batteries are no longer available to the public but are still produced for military and medical equipment, where a stable current and long service life are essential. Their recycling is tightly regulated. In hospitals, they are used in cardiac monitors, pH meters, oxygen analyzers, and telemetry instruments.
Button cell batteries are defined as the small coin-shaped or button-shaped batteries that have a diameter greater than their height. They are used in a wide variety of products including toys, cameras, calculators, watches, hearing aids, greeting cards, digital thermometers, pace makers, bicycle speedometers, stop watches and remote controls. There are four different subtypes of button cells: alkaline manganese, silver oxide, zinc-air and lithium. Of these, only the lithium batteries contain no intentionally added mercury. In the other three varieties, a mercury coating is added to the cell to prevent the formation of hydrogen gas that can result in battery leakage and malfunction. During normal usage, there is minimal risk of mercury exposure to the consumer, but in the event of breakage or disposal in a landfill, the mercury becomes a hazard.
Consumers should also be aware that there are products that look like typical alkaline batteries that actually contain a stack of button-cells inside. These are either silver oxide or alkaline manganese batteries and typically also contain mercury. They may be used in dog collars for invisible fences, garage door openers and vehicle locks.
The United States passed the Battery Management Act in 1996 which prohibited the sale of mercuric oxide cells, but allowed up to 25 milligrams of mercury to be added to alkaline manganese button cell batteries. According to a 2004 report by the Lowell Center for Sustainable Production for the Maine Department of Environmental Protection, in 2002 US-manufactured button cells had the following average amounts of mercury: silver oxide, 2.5mg; zinc air, 8.5mg; and alkaline manganese, 10.8mg. At the time the legislation was passed, the technology did not exist to make miniature batteries without mercury, but manufacturers have been working to eliminate the mercury and there are now mercury-free alternatives available. Originally, the mercury-free batteries cost about 30% more than the mercury-containing varieties, but the differential is not as great today.
While sales are somewhat regulated, there are no federal standards for the labeling, use or disposal of button cell batteries. In 2002, NEMA estimated that a minimum of 339 million mercury-containing button-cell batteries were sold in the United States by its members. This number would not include any imported button-cell batteries for which there are no firm estimates. Few of these batteries are currently recycled.
In preparation for a law that will go into effect in June 2011 that bans the sale of most mercury-containing button batteries, the state of Maine Department of Environmental Protection issued a report in January 2009 on the availability of mercury-free button-cell technology. It estimates that annual U.S. button battery sales account for somewhere between 3.3 and 4.6 tons of mercury. It also reports that most sizes of button-cell batteries are available to consumers in mercury-free versions.
Finally, although rare, consumers should be aware that ingestion of button-cell batteries can have serious health consequences. The American Association of Poison Control Centers reports that in 2002, there were 10 cases of life-threatening or disabling outcomes from ingesting miniature batteries. Approximately 0.1% of all calls to poison control centers involve the ingestion of button-cell batteries, usually by children or seniors. Almost half of these were hearing aid batteries.
Take action:
- Buy batteries that contain no mercury. Either use lithium button-cells where they are available or look for mercury-free button-cells of the other three types. For example, Sony recently introduced its LR44-ECO which is a mercury-free alkaline manganese battery.
- Consider the type of batteries that an item uses when you purchase it.
If you must buy button cell batteries that contain mercury or are not sure if a battery contains mercury, make sure that it gets recycled, not disposed of in regular household waste. Until you can dispose of them, make sure they are stored in a child-safe container and kept out of reach of children. Many areas have household hazardous waste days at which they will accept these batteries. - If you have a lot of batteries or run a small business or organization, consider using one of the companies that provide prepaid recycling buckets for batteries of all varieties:
- For old hearing aid batteries, some pharmacies, nursing homes and audiologists’ offices provide recycling.
- Look for recycling symbols on your rechargeable batteries (samples below). Most rechargeable batteries (not just button cells) contain toxic metals and should be recycled. Go to www.call2recycle.org and enter your zip code for a recycling drop off point near you.
