In this article, the subject of environmental damage by mercury from lamps and its prevention is examined in an American perspective by Philips Lighting:
Philips Lighting supports the reduction of mercury at its source as the environmentally responsible approach to make things better. Low mercury lamps are the best option for the environment and for the end-user that desires non-hazardous lamps. The United States Environmental Protection Agency's (EPA) Toxicity Characteristic Leaching Procedure (TCLP) is used by the Federal Government and by most states in order to determine whether or not spent fluorescent lamps should be characterised as hazardous waste.
For linear fluorescent lamps only leaching of mercury is critical for passing TCLP. Alto fluorescent lamps by Philips Lighting have the lowest mercury doses available in the market and pass the TCLP test because of this low mercury dose. No additive materials that help to pass the TCLP test are used. Other TCLP compliant linear fluorescent lamps (available from GE and Osram-Sylvania) pass the TCLP test due to the use of 'additives' (materials added to the lamp with the objective of reducing mercury leaching in the TCLP laboratory test). The mercury content of these TCLP compliant is equal to non -TCLP compliant lamps available from these companies and much higher than the mercury content in Alto lamps.
These additives are likely to be inefficient in preventing mercury leaching in real-world lamp disposal conditions and Hg leaching in the environment will presumably be higher for these lamps than for low mercury Alto lamps.
In addition to a leaching test the state of California has a total threshold limit for mercury for hazardous waste qualification. Philips Alto linear fluorescent lamps are the only lamps available that are classified as non-hazardous waste in California. Other states are considering implementing a total mercury threshold as well.
Low mercury lamps:
1) Low mercury fluorescent lamps: Mercury (Hg) is an essential component of fluorescent lamps. The mercury discharge is the most energy efficient and environmentally friendly source of light generation in these lamps. Unfortunately Hg is a hazardous material. Legislation has been developed in order to reduce Hg contamination in the environment. Fluorescent lamp manufacturers have reduced the Hg content in the lamps and are providing lamps that comply with legislation to be non-hazardous waste upon disposal.
Philips Lighting has clearly taken the lead in low mercury lamps. In 1995 Philips introduced the Alto family of non-hazardous TCLP compliant lamps. Others have followed, but Philips continues to have the lowest mercury lamps.
The leadership of Philips is a result of more than ten years of research and on precise Hg dosing and reduced Hg consumption of the lamp during operation ('Alto technology'). By using special coatings and phosphors Philips Alto lamps allow a low Hg dose to be used without loss in lamp life and lamp performance. In fact, less Hg consumption means better lamp performance during life (Hg consumption causes phosphors and glass to turn grey which reduces light output). The company has also developed and invested in a special Hg dosing method that offers the most accurate Hg dosing available while minimising mercury exposure in our factories.
2) Hazardous waste classification of fluorescent lamps: The United States Environmental Protection Agency's (EPA) Toxicity Characteristic Leaching Procedure (TCLP) is used by the Federal Government and most states to determine whether or not spent fluorescent lamps should be characterised as hazardous waste. Some States use additional tests or criteria and a few have legislated or regulated that all fluorescent lamps are hazardous whether or not they pass the various tests. For those States that use TCLP, to determine the status of linear fluorescent lamps, the mercury content is the critical factor. In order to minimise variability in the test, the National Electrical Manufacturers Association (NEMA) developed a standard how to perform TCLP testing on linear fluorescent lamps (NEMA Standards Publication LL 1-1997).
TCLP testing of fluorescent lamps:
TCLP testing of fluorescent lamps consists of the following steps:
· ALL lamp parts are crushed or cut into small pieces to ensure all potential hazardous materials will leach out in the test.
· The lamp parts are put in a container and an acetic acid buffer (pH=5) is added. A slightly acidic extraction fluid is used to represent typical landfill extraction conditions.
· The closed container is tumbled end-over-end for 18 hours (30 revolutions per minute).
· The extraction fluid is then filtered and the Hg that is dissolved in the extraction fluid is measured.
The average test result must be lower than 0.2-milligram mercury per litre extraction fluid for the lamp to be qualified as non-hazardous waste.
The TCLP test is a laboratory test meant to represent typical landfill conditions. The EPA developed this the test in order to reduce leaching of hazardous materials in the environment. Of course such a test is a compromise between the practicality of testing a large variety of landfill materials and actual landfill conditions (obviously, not every landfill has a pH of 5, metal parts are normally not cut, etc).
California has a more rigorous testing procedure for non-hazardous waste classification. The Total Threshold Limit Concentration (TTLC) also need to be passed in order for a fluorescent lamp to be classified as non hazardous waste. The TTLC requires a total mercury concentration of less than 20 weight ppm: for example a F32T8 lamp with a typical weight of 180 grams must contain less than 3.6 milligrams of mercury. Philips is currently the only lamp manufacturer to offer a linear fluorescent ALTO lamp range that complies with TTLC and is not hazardous waste in California.
3) The use of additives to pass TCLP For fluorescent lamps the soluble Hg content measured by the TCLP test is mainly determined by:
· The amount of soluble Hg that is used (consumed) in the lamp as ionic Hg(2+).
· The total Hg content (metallic Hg and ionic Hg) as demonstrated by the fact that TCLP increases for higher Hg doses, even for lamps that do not contain ionic Hg. Metallic Hg is less soluble than ionic Hg. As ionic Hg increases with lamp operation, TCLP increases for longer lamp life.
· Lamp-parts influencing the ionic to metallic mercury equilibrium in the TCLP solution. Examples are materials capable to reduce ionic Hg (such as metals or reducing agents) or materials that change the pH (acids, bases). The effect of these materials on TCLP can be very significant and can easily account for the difference in failing or passing TCLP. Manufacturers have different ways of manufacturing TCLP compliant fluorescent lamps.
· Philips Alto lamps have no added materials that help pass TCLP. Philips has ensured that Hg consumption during life is low using 'TCLP neutral' solutions. Coatings and special phosphors do not effect the TCLP. Then, using an accurate Hg dosing technology, a mercury dose is applied that is low enough to allow the lamps to pass TCLP and other tests such as TTLC.
· For our competitors' fluorescent lamps the difference between TCLP compliant lamps and conventional lamps is not a lower Hg content. These manufacturers choose to pass TCLP by using special materials that are designed to make their lamps pass the TCLP test. These materials have no effect on lamp operation and are introduced in the lamps for the purpose of passing the TCLP test. Although their lamps have somewhat lower Hg levels than several years ago, the reason they pass TCLP is due to the use of these additives.
Different additives are used: GE puts ascorbic acid (an acid and a strong reducing agent) into the cement used to fix the lamp caps; Osram-Sylvania mixes copper-carbonate in this cement or applies zinc plated iron lamp caps (copper, iron, and zinc ions reduce soluble Hg). These additives are found in 1999 and early 2000 produced lamps.
The use of additives reduces the soluble Hg measured by the TCLP test in laboratories and is as such a legitimate way to produce TCLP compliant fluorescent lamps. Unfortunately, the 'additive approach' does not reduce the amount of hazardous mercury in the environment. More importantly, the additives may not work as effectively in 'real world' lamp disposal as they do in the laboratory TCLP. In 'real world' disposal the lamp caps are not cut to pass a 0.95 cm sieve, are not tumbled intensively with all other lamp parts for 18 hours, and so forth. Therefore, the additives that become available during the TCLP test to reduce mercury leaching, may not, or only partly, do their job in real world disposal. As a consequence lamps that rely on additives to pass TCLP may still have relatively high amounts of mercury leaching out in the environment.
Low mercury is a much better way to go:
Obviously, the amount of mercury that leaches out in real life will depend strongly on the type of additive and the exact disposal conditions. Clearly the 'additive' approach is not a guarantee that only small amounts of mercury will leach into the environment upon disposal. The low mercury approach is a much better way to go since it actually reduces the amount of mercury that can leach out, no matter what the exact disposal conditions are.
Several states (New Jersey, Delaware) have addressed the additive issue. They have indicated that if lamps with additives were thrown away as non-hazardous waste and later found to behave differently in the landfill, generators and those who dispose of such lamps could potentially face the possibility of having violated the hazardous waste disposal regulation known as RCRA. California has a total Hg threshold as indicated before, and some other states are considering the option of a total Hg threshold as well.
The signals are clear. Low mercury lamps are the best option for the environment and for the end-user that desires non-hazardous lamps.
Contact (In the United Kingdom):
Philips Lighting UK Ltd.,
The Philips Centre,
420-430 London Road,
Croydon, Surrey CR9 3QR
Tel: 020 8665 6655
Fax: 020 8665 5104