Thanks Green Baby for raising this issue. It is an important one and something we all need to be aware of as consumers and users of this technology.
Yes mercury is a poisonous substance which can be dangerous potentially causing physical and neurological disturbances in the human body to varying degrees with some quite severe if ingested or inhaled in large enough quantities.
However it is important to keep in mind as highlighted by Chandra’s Snopes link, a balanced and sober view is necessary when considering the health risks of any technology, as invariably depending on how deep we look, the angle at which we look, what we choose to accept or ignore are important factors.
The World Health Organisation suggests 0.3 micrograms/kilogram/day is the safest upper limit of mercury exposure for humans. So someone who weighs 70kg (11 stone) could safely consume approximately 7 to 20mg per day (50 – 140 mg per week).
If we turn our attention to foods and fish, (a major concern in mercury ingestion) we could easily consume 1 once of tuna per day every week (one once of tuna contains approximately 4.8 micrograms of mercury) and be within safe levels of mercury consumption. Bearing in mind different fish contain different levels of mercury – typically the larger the fish the greater the mercury content per ounce.
Ironically, if we look at why we have mercury content in fish, the answer leads us back to our energy supply and consumption.
40% of all mercury released into our atmosphere is a result of the energy produced at our coal fired power stations.
Mercury released from power stations linger in our atmosphere until it rains, falling into our seas and rivers where it is eventually converted into what’s known as methylmercury one of many forms of mercury, but in this case a form easily absorbed by very small organisms. When fish eat these organisms they ingest the methylmercury and so the mercury moves up the food chain. The bigger the fish the more methylmercury it consumes – the bigger the fish we eat the more mercury we consume.
It’s more likely we consume more mercury from eating fish 3 – 4 times per week than we would from exposure to a broken CFL. CFL’s contain on average 3 – 4 milligrams of mercury per lamp (limited at 5 milligrams per lamp) almost 1000 times less than mercury in a thermometer.
One US research department (see link below) found that between 17% – 40% (up to 0.67mg) of the mercury contained in a fluorescent tube was released into the atmosphere when the tube was broken, with one third released within the first eight hours. Typically only a fraction of this might be ingested resulting in a similar amount ingested to that of eating a tin of tuna.
As it turns out, our use of CFL’s may well be of greater harm to others than to us in the UK, as:
• An increased demand for CFL’s means an increased demand for mercury and mercury mining.
• Poorly regulated factories mean factory workers in China and other developing countries are exposed to harmful levels of mercury over prolonged periods of time.
These scenarios may we be exceptions to the rule in some cases but are relevant. In the mean time we do need to follow guidelines and handle mercury containing products with care.
You can dispose of your CFL’s at one of Brent’s re-use and recycling centres.
http://www.brent.gov.uk/streetcare2.nsf/Recycling%20Sites/LBB-63?OpenDocument&pp=200084
However CFL’s may well be an interim measure before LED lighting technology becomes more mainstream, cheaper and more readily available.
Useful links:
http://www.state.nj.us/dep/dsr/research/mercury-bulbs.pdf
http://www.fda.gov/Food/FoodSafety/ProductSpecificInformation/Seafood/FoodbornePathogensContaminants/Methylmercury/ucm115662.htm
http://www.timesonline.co.uk/tol/news/world/asia/article6211261.ece
