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Compact fluorescent lamps: a radioactive surprise

Nuclear Monitor Issue: 

(March 9, 1990) As energy efficiency became a widespread concern following the oil price shock of the early 1970s, the lighting industry made significant strides in providing a range of lighting alternatives with improved efficiency and longer service lives.

(329.3293) WISE Amsterdam - One of the most exciting areas of technological improvement has been in the new generation of fluorescent lamps known as compact fluorescent. However, concerns have been raised as information has come out that some of these lamps contain radioactive materials. Some of these concerns are raised in an article Dave Martin in the Winter edition of Nuclear Awareness News, a publication of the Canadian environmental group, the Nuclear Awareness Project.

According to the article, in the early 1980s, the Philips Lighting Co. introduced in Europe what it called a "PL" fluorescent, later called by others a compact fluorescent lamp (CFL). Philips was soon followed by Osram, another lighting company. The CFLs have a number of unique features, including the facts that they use lower wattages (5 to 13 W) than had ever been used before in rluorescents and that their small high-efficiency ballasts attached at the base of the lamp with an Edisontype medium screw base allowed them to directly replace incandescent lamps. In addition, light quality from the CFLs is good because of the improved ballasts, better lamp gas, and new tristimulus phosphor coating on the tube. They have a "warmer" light and none of the strobe effect of the older fluorescents. Their big advantages, however, are efficiency and long service life.

Some of the disadvantages to CFLs include an apparent problem in price, as the initial price of the CFL is high. However, the ballast is reusable and, when the price of electricity is included, the CFLs are clearly cost savers over time.

So what, asks the articles author, about the radioactive materials in these lamps? All fluorescents, he says, use ballasts, which transform electrical current for starting and operating the lamps. The ballast provides several volts to heat an electrode so that an arc can pass from one electrode to the other. The current of the arc energizes phosphors which are coated on the inside of the glass tube. More voltage is required for the arc. For starting, some CFLs may use the help of ionizing radiation from a radioactive substance in a "starter" or "glow switch" to warm up the electrode and provide initial ionization, especially at low temperatures.

There are three radionuclides in common use in CFLs: Krypton-85 (Kr-85), promethium-147 (Pm-147), and tritium (H-3). These radionuclides are used in very small amounts - typically billionths of curies, known as nanocuries (nCi) (see chart).


Radioactive Materials in Philips Compact Fluorescent Lamps

PL Lamps ('twin tube') 5, 7, 9, 13W
- less than 30 nCi krypton-85

PLC cluster Lamps/15mm ('quad cubes') 16,22, 28 W
- less than 330 nCi promethium-147

PLC Cluster Lamps/10mm ('quad tubes') 10, 13, 18, 26 W
- less than 500 nCi tritium

SL Lamp with Integrated Magnetic Ballast 18W
- less than 110 nCi tritium

Kr-85 is a chemically inert noble gas that emits beta particles and emits a 0.41%-probable gamma ray. It has a half-life of 10.76 years. The major exposure pathways are through the skin and lungs.

Pm-147 is a rare earth metal, similar to the tristimulus phosphors used for coating the fluorescent tubes. It is a solid and emits beta particles. Its half-life is 2.62 years. Under international standards, the maximum permissable body burden for Pm147 in the critical organ (bone) is two microcuries, or six times the amount in one lamp. The maximum permissable continuous exposure level for the public is 0.67 nCi/m3 for air, and the maximum permissable intake by inhalation is 60 micro-curies per quarter, or about 182 times the amount in one lamp.

Tritium is also a beta emitter. It has a half life of 12.3 years. In its elemental form, tritium is a gas, and in that form is considered much less dangerous than in its oxidized form as tritiated water or water vapour. It has been estimated that a lethal dose (LD50/30causing death to 50% of subjects within 30 days) is about 70 Ci tritiated water for a man weighing 70 kg. Much smaller quantities constitute a serious risk if ingested, inhaled or absorbed through the skin. Fire is a serious consideration here, since it would result in the immediate oxidation of exposed elemental tritium.

Among the controversial aspects of using radionuclides in CFLs is the question of labeling. Nuclear Awareness Project has discovered that in the US, the Nuclear Regulatory Commission (NRC) requires labeling of the boxes of CFLs which contain radioactive materials- although the lamps themselves are not labeled. For example, Philips PL boxes are labeled with the following wording: "This lamp uses a glow switch containing less than 30 nCi Kr-85". That's all well and good, except it does not tell the consumer outright that the product contains radioactive material, and it uses scientific short forms for nanocuries and radioisotopes which would not be understandable to the average person. Still, it's at least something. In Canada, there's no labeling at all, making it impossible for most consumers to make an Informed choice. The Canadian Atomic Energy Control Board (AECB) considers that there are such small quantities of radioactive material involved in CFLs that it is below regulatory concern.

In addition to concern about the lamps themselves, there is the question of safety during the manufacturing process, as well as the transport and storage of the radionuclides prior to manufacturing. Then there's the matter of uncontrolled disposal of the lamps. And, says the author, in a more general sense, it is also unfortunate that the use of these radionuclides in consumer goods offers more economic support and justification for the commercial and military nuclear industry, which is the supplier.

In the US, the environmental community is divided on support for CFLs. The Rocky Mountain Institute in Colorado (founded by soft-energy advocate Amory Lovins), has argued that the benefit in energy savings from CFLs far outweighs the disadvantage of containing radioactive material. By contrast, Nuclear Free America, based in Maryland, has taken a position strongly against the use of CFLs, arguing that they foster a continuing reliance on the nuclear industry and the risks and costs simply outweigh the benefits. They are promoting the use of a more efficient incandescent lamp.

But, says Martin, the good news is that there are CFLs that do not contain radioactive material: In particular, the CFLs with electronic ballasts, which do not need radioactive material for their starters. The Osram "Dulux EL" , for example, is a quad tube electronic CFL available in 7, 11, 15 and 20 watts. It has an integral electronic ballast, and because it is a quad lamp, it is shorter and fits easily in most incandescent fixtures. It is not yet available on a retail basis, but is being installed in commercial and industrial locations. The bad news is that it will cost more. The Osram Dulux D (a high performance quad tube CFL in 10, 13, 18, 26 watts) and the Dulux DIE (similar to the Dulux D, but capable of dimming) have no glow switch, and therefore no radioactive materials. The Philips SL18 with the integrated electronic ballast has no radioactive material (although the SL18 with the magnetic ballast uses tritium - see chart) and the longer length Philips PL lamps (18, 24, 36 watts) are likewise radiation-free.

Sources: Nuclear Awareness News (Canada), Winter 1989/1990.

Contact: Nuclear Awareness Project, Box 2331, Oshawa, Ontario, L1H 7V4.