Sustainable Hospitals - Mercury Information Package

Mercury Reduction
Best Management Practices for
Mercury-containing Products in the Hospital
Batteries

Mercury-containing batteries
Mercuric oxide (mercury zinc) batteries and button batteries are the only batteries made in the United States that may contain added mercury if newly purchased (see table). Mercuric oxide batteries offer a reliable and constant rate of discharge and can be made in a wide variety of sizes intended for use in medical devices. In the 1990s, manufacturers stopped designing equipment that requires mercuric oxide batteries. New models generally require zinc air batteries. However, mercuric oxide batteries may remain in hospital stock for many years for use in older equipment. The shelf life of mercuric oxide batteries is up to ten years.

Some of the medical devices that may still require mercuric oxide batteries include cardiac monitors, pH meters, oxygen analyzers and monitors, and telemetry instruments.

The alternative for mercuric oxide batteries is zinc air batteries. However, the alternative may not be mercury-free. A zinc air button battery may contain up to 25 mg of mercury. Larger zinc air batteries are made up of stacked button batteries, each of which may contain up to 25 mg of mercury. It is not yet possible to eliminate mercury from these batteries. In the absence of mercury, the zinc electrode corrodes and creates hydrogen gas. Because the batteries are tightly sealed, they can bulge when the gas is created and may even explode. Note that zinc air batteries include a tab that prevents exposure of the internal part of the battery to air (air serves as one of the electrodes). Once the tab on a zinc air battery is pulled off, the internal part of the battery is exposed to air and it begins to discharge.

For medical devices, there are Food and Drug Administration and Underwriters Laboratory certification concerns with replacing a battery. It is important to contact the equipment manufacturer before replacing a mercuric oxide battery with a substitute to ensure that the device has been approved for use with the alternative battery.

Rechargeable (nickel-cadmium) batteries cannot be used as an alternative to mercuric oxide batteries.

Recycling/disposal of batteries
Provide many convenient collection points for batteries throughout the hospital, including areas where replacement batteries are obtained. There are two options for collection:

Collect only mercury-containing batteries. This would put the responsibility for knowing mercury content on the person who is discarding the battery. The hazardous waste management coordinator could post written guidance at the collection location. However, this option could be confusing for the user.
Collect all batteries. The hazardous waste management coordinator or recycler would take responsibility for sorting the batteries. The coordinator should determine which types of used batteries are hazardous waste, which types can be recycled and which types can be thrown away as trash. Spent mercury-containing batteries should be recycled.

Some battery manufacturers offer recycling programs for mercuric oxide batteries. Check with the hospital's battery suppliers to learn if they have collection plans and if they will coordinate packaging and transportation to their facilities. Check with the appropriate local and state agencies to ensure that the specific program is legal.

Best
Management Practices

Fever Thermometers

Sphygmomanometers

Gastrointestinal Tubes

Dental Amalgam and Mercury

Laboratory Chemicals

Pharmaceutical Products

Cleaners and Degreasers

Batteries

Lamps

Electrical Equipment

Thermostat Probes in Gas Appliances