Tritium

Certain older exit signs contain the radioactive isotope tritium and, therefore, must be handled properly at the end of their useful life. According to the Environmental Protection Agency, some landfills are now finding tritium in their leachate, indicating that exit signs are being improperly disposed.

Background

Gaseous tritium light source (GTLS) exit signs use the radioactive decay of hydrogen into helium to glow, using the radioactive isotope tritium. The advantage of a tritium exit sign is that it continues to glow regardless of power failure, providing a safe beacon in time of emergency. Tritium is found in a gaseous form inside tubes in these signs, and emits a low-level beta radiation which is easily shielded within the sign. The Nuclear Regulatory Commission (NRC) oversees the regulation of tritium and the proper disposal of GTLS exit signs.

Because tritium emits low-level beta particles, it does not pose a serious health risk when properly handled. Gaseous tritium radiation cannot pierce skin, and therefore must be ingested to cause damage. However, when tritium exit signs are broken or improperly disposed, the tritium can be released and ingested by people in the immediate vicinity through inhalation. Tritium reacts with oxygen to form tritiated water, which poses a greater health concern. Tritiated water looks no different than safe water, and has a much higher absorption rate. Tritium can be absorbed through skin in tritiated water, and can be ingested to cause damage. Tritium exposure has been linked to reproductive problems, genetic abnormalities, development problems, and other health problems in laboratory animals.

Tritium levels exceeding safe levels set by the EPA in landfill leachate suggest the tritium exit signs are being improperly disposed of. There are millions of tritium exit signs in the United States, and many lack adequate regulatory accountability. Although most landfills are aware of the regulations for disposal of tritium, many small businesses may find proper disposal to be too costly (estimated at $75 per sign), or are simply unaware that tritium is subject to regulation by the NRC. This leads to improper and illegal disposal in landfills, which can mean high levels of tritiated water and health concerns. Broken tritium exit signs also pose a threat if people are unaware of proper cleanup methods, and people exposed in the proximity may be affected.

Alternatives

Over 90 percent of exit signs being installed today use light-emitting diode (LED) technology. LED exit signs can last as long as 25 years using lamps requiring only 2 to 5 watts of power. The LED exit signs do not use tritium, and have the advantage of cheaper disposal and less regulatory oversight. However, LED exit signs rely on emergency sources of power which, unlike tritium exit signs, can potentially fail during an emergency.

An emerging alternative, marketed since the early 1990s, are photoluminescent (PL) exit signs. PL exit signs use a non-radioactive compound of strontium oxide aluminate to store the ambient light around the sign, and if that light goes out the PL sign will release the stored energy as a glow. PL exit signs have advantages over both LED and tritium exit signs because they are both non-toxic and non-electrical, while being economically competitive.

Disposal

The EPA has developed a training program to encourage responsible disposal of unwanted tritium exit signs. Using a step-by-step approach, the training hopes to make more people aware of the health risks posed by the improper disposal of tritium exit signs, the costs and liabilities of tritium exit signs, the best practices for handling and disposing of tritium exit signs, and available alternatives.

There are many factors to consider when a building’s construction or demolition aims for sustainable design. We usually think about the big things -- the tons of concrete recycled or large-scale energy saving design. EPA has recently raised the issue of a small but vital component of our buildings, exit signs. In the past, a common option for exit signs was the tritium exit sign. These signs use the radioactive nature of the isotope tritium to glow even when there was no source of electricity, providing a reliable light beacon in case of emergency. However, buildings have moved away from radioactive sources for exit signs because of the liabilities and potential health risks associated with tritium, which is regulated by the NRC.

Background

Because tritium emits low-level beta particles, it does not pose a serious health risk when properly handled. Gaseous tritium radiation cannot pierce skin, and therefore must be ingested to cause damage. However, when tritium exit signs are broken or improperly disposed, the tritium can be released and ingested by people in the immediate vicinity through inhalation. Tritium reacts with oxygen to form tritiated water, which poses a greater health concern. Tritiated water looks no different than safe water, and has a much higher absorption rate. Tritium can be absorbed through skin in tritiated water, and can be ingested to cause damage. Tritium exposure has been linked to reproductive problems, genetic abnormalities, development problems, and other health problems in laboratory animals.

Tritium exit signs can be identified easily if properly labeled. However, due to the aging of these signs identification is sometimes not so easy. An easy way to identify a tritium exit sign is if the sign has letters which appear clear or white in the light, but glow green in the dark.

Whether engaged in construction or demolition, there are important factors to take into consideration concerning exit signs. Tritium levels exceeding safe levels set by the EPA in landfill leachate suggest the tritium exit signs are being improperly disposed of. Tritium exit signs are strictly forbidden from landfills for their potential to affect the surrounding area in the form of tritiated water. When a building is being renovated with new exit signs, or the signs are being disposed of, it is important to know all of the regulatory obligations involved with tritium exit signs.

Alternatives

When purchasing new exit signs, today there are alternatives to tritium. In fact, over 90 percent of exit signs being installed today use light-emitting diode (LED) technology. LED exit signs can last as long as 25 years using lamps requiring only 2 to 5 watts of power. The LED exit signs do not use tritium, and have the advantage of cheaper disposal and less regulatory oversight. However, LED exit signs rely on emergency sources of power which, unlike tritium exit signs, can potentially fail during an emergency.

An emerging alternative, marketed since the early 1990s, are photoluminescent (PL) exit signs. PL exit signs use a non-radioactive compound of strontium oxide aluminate to store the ambient light around the sign, and if that light goes out the PL sign will release the stored energy as a glow. PL exit signs have advantages over both LED and tritium exit signs because they are both non-toxic and non-electrical, while being economically competitive.

Disposal

The EPA has developed a training program that details the concerns of tritium exit sign disposal and the proper methods to conduct disposal, as well as further discussing the alternative options.

Gaseous tritium light source (GTLS) exit signs use the radioactive decay of hydrogen into helium to glow, using the radioactive isotope tritium. The advantage of a tritium exit sign is that it continues to glow regardless of power failure, providing a safe beacon in time of emergency. Tritium is found in a gaseous form inside tubes in these signs, and emits a low-level beta radiation which is easily shielded within the sign. The Nuclear Regulatory Commission (NRC) oversees the regulation of tritium and the proper disposal of GTLS exit signs.

Background

Because tritium emits low-level beta particles, it does not pose a serious health risk when properly handled. Gaseous tritium radiation cannot pierce skin, and therefore must be ingested to cause damage. However, when tritium exit signs are broken or improperly disposed, the tritium can be released and ingested by people in the immediate vicinity through inhalation. Tritium reacts with oxygen to form tritiated water, which poses a greater health concern. Tritiated water looks no different than safe water, and has a much higher absorption rate. Tritium can be absorbed through skin in tritiated water, and can be ingested to cause damage. Tritium exposure has been linked to reproductive problems, genetic abnormalities, development problems, and other health problems in laboratory animals.

Product Alternatives

From a procurement perspective, there are much better options for these important fixtures that are economically viable. In fact, over 90 percent of exit signs being installed today use light-emitting diode (LED) technology. LED exit signs can last as long as 25 years using lamps requiring only 2 to 5 watts of power. The LED exit signs do not use tritium, and have the advantage of cheaper disposal and less regulatory oversight. However, LED exit signs rely on emergency sources of power which, unlike tritium exit signs, can potentially fail during an emergency.

An emerging alternative, marketed since the early 1990s, are photoluminescent (PL) exit signs. PL exit signs use a non-radioactive compound of strontium oxide aluminate to store the ambient light around the sign, and if that light goes out the PL sign will release the stored energy as a glow. PL exit signs have advantages over both LED and tritium exit signs because they are both non-toxic and non-electrical, while being economically competitive.

The EPA has developed a training program that details why exit signs are an important part of a green procurement plan, and further discusses the alternative options.