Mercury In Florescent Light Bulbs
Estimates are that as much as 25% of the average home energy budget is spent on electric lighting¹. Compact florescent lights have made a huge impact into the environmental scene in recent years because of their energy efficiency. They are extremely energy efficient. Some manufacturers claim things such as: compact florescent lamps are 4 times as efficient as regular light bulbs, they last 10 times as long as regular light bulbs, replacing a single light bulb with a compact florescent bulb will keep a half ton of CO2 out of the atmosphere, and if everyone in the U.S. used energy-efficient lighting, we could retire 90 average size power plants. In truth, there is little reason to doubt these claims. They are certainly much more efficient. There has been much recent debate however on the actual environmental impact of compact florescent lights after the public became aware of the amount of mercury that was in the bulbs.
Of course, it should not come as a surprise that Mercury is found in compact florescent bulbs. Compact florescent bulbs are basically tiny versions of the full sized florescent bulbs we are more familiar with which contain mercury.
Mercury is a very harmful environmental contaminant. It is not beneficial to the body in any amount3, is a potent neurotoxin6, 7, and has been linked to autism5. Recently, much news has been on mercury poisoning in fish especially sushi.
Manufacturers claim that there is very little mercury in the bulbs. Some sight that there is less mercury in some than in a common watch batteries. One article stated that there is more mercury in some tooth fillings than in the average compact florescent light bulb. Of course, the consumer should not be taken in by this last statement. The mercury in amalgam fillings is a different chemical species and is not toxic to the human body. For a more complete discussion of mercury in amalgam fillings see this post.
The real issue is the fragility of the light bulbs. If a florescent bulb breaks the mercury is released. This is a major problem because it is much easier for a watch battery to reach the landfill unharmed than it is for a glass bulb. Not only does this mercury get released to the environment (which can eventually find its way into fish believe it or not), but it also exposes city workers to high levels of a potent neurotoxin. Some cities have placed ordinances on putting compact florescent bulbs in the trash. Most major cities offer recycling options for florescent bulbs.
Therefore, the major question becomes: what is the actual environmental impact of compact florescent bulbs? Does the mercury pose a greater threat to the environment than the increased carbon emissions of less efficient traditional bulbs, or is the mercury of much smaller environmental impact?
In a recent paper entitled, “Release of mercury from broken fluorescent bulbs11” Aucott, McLinden, and Winka develop a method for measuring mercury released from broken bulbs. They found that between 17 and 40% of the mercury in broken low-mercury fluorescent bulbs is released to the air during a two-week period immediately following breakage which is approximately between 3 and 8 mg of elemental mercury vapor11. Approximately 620 million fluorescent bulbs are discarded annually in the United States, and many are broken during disposal. Based on the estimated release rate of 3-8 mg per broken bulb developed in this study, discarded bulbs release approximately 2-4 tons of mercury per year in the United States11.
That is certainly a significant amount of mercury being released to the environment every year in the United States. However, it should be recognized that our total carbon footprint is also reduced quite a bit from their use. My personal opinion is that use of compact florescent bulbs should be encouraged as long as recycling technologies are easily accessible and the public becomes aware of the proper disposal process.
1. http://www.eartheasy.com/live_energyeff_lighting.htm
2. Importance of wetlands as sources of methyl mercury to boreal forest ecosystems
St. Louis, VL; Rudd, JWM; Kelly, CA; Beaty, KG; Bloom, NS; Flett, RJ
Canadian Journal of Fisheries and Aquatic Sciences [CAN. J. FISH. AQUAT. SCI.]. Vol. 51, no. 5, pp. 1065-1076. 1994.
3. http://dcnutrition.com/minerals/minerals.cfm
4. Mercury methylation in aquatic systems affected by acid deposition; Gilmour CC, Henry EA, Environ Pollut. 1991; 71(2-4):131-69
5. Autism: a novel form of mercury poisoning; S. Bernard, A. Enayati, L. Redwood, H. Roger and T. Binstock; ARC Research, Cranford, New Jersey, USA
6. Methylmercury poisoning: long-term clinical, radiological, toxicological, and pathological studies of an affected family; Davis LE, Kornfeld M, Mooney HS, Fiedler KJ, Haaland KY, Orrison WW, Cernichiari E, Clarkson TW; Ann Neurol. 1994 Jun;35(6):680-8
7. Iatrogenic exposure to mercury after hepatitis B vaccination in preterm infants;
Stajich GV, Lopez GP, Harry SW, Sexson WR; J Pediatr. 2000 May;136(5):679-81
8. Personal Presentations in Biogeochemistry; Texas A&M University; Dr. McGuire
9. People with high mercury uptake from their own dental amalgam fillings; L Barregard, G Sallsten and B Jarvholm; Occupational and Environmental Medicine, Vol 52, 124-128
10. Regional differences in worldwide emissions of mercury to the atmosphere; Nicola Pirrone, Gerald J. Keeler and Jerome O. Nriagu; Atmospheric Environment Vol. 30, No. 17, pp. 2981 2987, 1996; Copyright © 1996 Published by Elsevier Science Ltd
11. Release of mercury from broken fluorescent bulbs; Aucott M, McLinden M, Winka M.; Journal of Air Waste Manag Assoc. 2003 Feb;53(2):143-51
12. The Materials Flow of Mercury in the Economies of the United States and the World; John L. Sznopek, Thomas G. Goonan; U.S. Geological Survey CIrcular 1197
13. Airborne Emission of Mercury from Municipal Solid Waste. I: New Measurements from Six Operating Landfills in Florida; Steven E. Lindberg, George R. Southworth, Mary Anna Bogle, T.J. Blasing, Jim Owens, and Kelly Roy; Environmental Sciences Division, Oak Ridge National Laboratory, Oak Ridge, TN
Mercury Poisoning Factbox
Mercury is a very common contaminant found in a variety of environments. Mercury is not beneficial to the body in any amount3, is a potent neurotoxin6, 7, and has been linked to autism5. Recently, much news has been on mercury poisoning in fish especially sushi. What are the facts on Mercury?
First, one of the central ideas of environmental toxicology is that the form of the contaminant determines its toxicity and its mobility. When told that an environment contains a certain contaminant environmental geochemists immediately ask, “What forms is it in?” The forms of Mercury are:
- Elemental Mercury (Hg0) – This form is volatile and is spontaneously oxidized in the presence of light
- Mercuric Ion (Hg2+) – salts, used in tanning and as disinfectants, kills/inhibits many microbes, toxic but rapidly excreted8
- Mineral (HgS) – Cinnabar
- Organic Mercurials (RHg+) – used as slimicide, paper industry, seed coating; two major forms are methylmercury and dimethylmercury
The form of mercury is very important in determining its toxicity. For example many of us have fillings in our teeth. Amalgam fillings are often 50% Mercury (As I type this my tongue goes to the top of my mouth and feels mine). However, it is in the elemental form Hg0. If your filling gets exposed to light by opening your mouth wide it is oxidized to Hg2+ and is almost entirely excreted through your urine9 (despite what some holistic medical 
websites may claim). Methylmercury, however, is the common type found in fish and other foods. Methylmercury is 100 times more toxic than Hg2+ and is very poorly metabolized and excreted from the body.
Mercury enters the atmosphere through natural and anthropomorphic sources. Some natural sources include: volcanoes, minerals, and volatilization from ocean. Some anthropomorphic sources are: coal combustion, waste incineration, dentistry, and metal processing. Most sources would say that humans have doubled or even tripled the amount of Mercury in the atmosphere10.
Through various activities, such as combustion of fossil fuels, Mercury has settled after volatilization to nearly form a blanket across the earth. Mercury has settled into the ocean sediment as well. The form is usually Hg0 or Hg2+ which is changed to methylmercury through uptake of organisms generally settling in their fatty tissue. Mercury is biomagnified as predators eat smaller fish and other aquatic animals. For this reason predatory fish will tend to have higher amounts of Mercury.
The story is not all bad. Just as Mercury can become more toxic by changing form it can also become detoxified. For instance, Methanogens (bacteria) can change Methylmercury to elemental Mercury through the reaction: CH3Hg+ → CH4+ Hg0. Another pathway is through microbes harboring heavy-metal resistance plasmids changing Hg2+ to Hg0. Lastly, Anoxic-Sulfate Reducers produce H2S ppt mercury through Hg2++ H2S → HgS, Hg2S.
Mercury is most harmful to women and children6,7, but men should be very careful as well. Fish are not harmed by the Mercury in their body. Therefore, they will accumulate Mercury without health effects to themselves. When the Mercury is transferred to humans however the effects can be drastic. One horrible example is the Minamata Disaster off of Minamata Bay in Japan in 1932-1969. Thousands of people living around the bay developed Methylmercury poisoning through the consumption of contaminated fish8. Mercury was dumped into the bay by Chisso plastics manufacturing company. Symptoms include tingling sensations, muscle weakness, unsteady gait, tunnel vision, slurred speech, hearing loss, and abnormal behavior, such as sudden fits of laughter. Some may remember the story of the Mad Hatter. In the mid-18th to the mid-19th centuries Mercury was used in the process of hat making through mercuric nitrate, Hg(NO3)2·2H2O which was added to separated the fur from the pelt. The vapors produced were highly toxic.
1. On the Chemical Form of Mercury in Edible Fish and Marine Invertebrate Tissue Bloom, NS; Canadian Journal of Fisheries and Aquatic Sciences CJFSDX, Vol. 49, No. 5, p 1010-1017, May 1992. 1 fig, 4 tab, 22 ref.
2. Importance of wetlands as sources of methyl mercury to boreal forest ecosystems
St. Louis, VL; Rudd, JWM; Kelly, CA; Beaty, KG; Bloom, NS; Flett, RJ
Canadian Journal of Fisheries and Aquatic Sciences [CAN. J. FISH. AQUAT. SCI.]. Vol. 51, no. 5, pp. 1065-1076. 1994.
3. http://dcnutrition.com/minerals/minerals.cfm
4. Mercury methylation in aquatic systems affected by acid deposition; Gilmour CC, Henry EA, Environ Pollut. 1991;71(2-4):131-69
5. Autism: a novel form of mercury poisoning; S. Bernard, A. Enayati, L. Redwood, H. Roger and T. Binstock; ARC Research, Cranford, New Jersey, USA
6. Methylmercury poisoning: long-term clinical, radiological, toxicological, and pathological studies of an affected family; Davis LE, Kornfeld M, Mooney HS, Fiedler KJ, Haaland KY, Orrison WW, Cernichiari E, Clarkson TW; Ann Neurol. 1994 Jun;35(6):680-8
7. Iatrogenic exposure to mercury after hepatitis B vaccination in preterm infants;
Stajich GV, Lopez GP, Harry SW, Sexson WR; J Pediatr. 2000 May;136(5):679-81
8. Personal Presentations in Biogeochemistry; Texas A&M University; Dr. McGuire
9. People with high mercury uptake from their own dental amalgam fillings; L Barregard, G Sallsten and B Jarvholm; Occupational and Environmental Medicine, Vol 52, 124-128
10. Regional differences in worldwide emissions of mercury to the atmosphere; Nicola Pirrone, Gerald J. Keeler and Jerome O. Nriagu; Atmospheric Environment Vol. 30, No. 17, pp. 2981 2987, 1996; Copyright © 1996 Published by Elsevier Science Ltd
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