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Harmful Substances Watch: Mercury
Fish have made this heavy metal quite famous, and restricted intake of fish has been recommended by a wide variety of public health organizations due to risk of mercury contamination. But do you know your mercury-and-fish limits? Canned tuna is the most likely source of mercury exposure for U.S. consumers who eat fish. Just how much can you eat each week and still stay safe?
FULL STORY:
Like all environmental toxins, mercury can be found in great variety of locations and amounts. Some oceans are lined with ores that contain natural mercury deposits. The Mediterranean Sea, for example, contains cinnabar (mercury sulfide) deposits that can leech into the water and find their way into Mediterranean fish. Tuna from the Mediterranean tends to be higher in mercury than tuna from the Atlantic or the Pacific for this reason.
Human activities, however, can be an equally significant source of mercury contamination. Over 100 tons of mercury are released annually into the air by U.S. industries - primarily coal-fired power plants, municipal waste combustion facilities, and incinerators that handle medical waste. Mercury also finds it way into landfills across the country in the form of fluorescent light bulbs, thermostats, and electrical components (including components still used in automobiles).
Once deposited in the soil or in the air, mercury can be transported by natural ecological forces to groundwater, rivers, and oceans. This movement of toxins through our environment (along pathways called "transfer vectors") can bring mercury into the natural habitat of fish thousands of miles away from the original site of contamination.
When it comes to canned light tuna, a good ballpark guideline for safe mercury intake can be based on body weight alone. For every 10 pounds of weight, allow yourself just under one ounce (technically, 0.95 ounces) of canned light tuna per week. If you weigh 150 lbs., for example, limit yourself to 14 ounces (or approximately 2 cans) of tuna. For canned albacore tuna, however, this restriction becomes much greater, because canned albacore averages substantially more mercury than canned light. With albacore, for every 10 pounds of weight, allow yourself only 1/3rd of an ounce per week. In this case, if you weigh 150 pounds, restrict yourself to 5 ounces (less than one can) per week.
While body weight can give you an initial ballpark estimate for restricting your canned fish intake, it's important to note that your body and your lifestyle are unique. You may have other important sources of mercury exposure, and you may have unique metabolic needs when it comes to detoxification of mercury inside your cells. For these reasons, a truly personalized assessment of your mercury exposure and mercury risk can be helpful for planning your fish intake (and other dietary decisions as well).
Several health organizations, including the U.S. Environmental Protection Agency (EPA), have issued advisories cautioning pregnant women (and women considering pregnancy) against excess consumption of mercury-containing fish. For the latest EPA advisory, click here.
References:
1. Adams DH. (2004). Total mercury levels in tunas from offshore waters of the Florida Atlantic coast. Mar Pollut Bulletin 49(7-8):659-63.
2. Hood, E. (2003). A diet rich in fish. High-end consumers face more mercury risks. Environ Health Perspect 111(4):A233.
3. Kraepiel AM, Keller K, Chin HB et al. (2003). Sources and variations of mercury in tuna. Environ Sci Technol 37(24):5551-8.
4. Schober SE, Sinks TH, Jones RL, et al. (2003). Blood mercury levels in US children and women of childbearing age, 1999- 2000. JAMA 289(13):1667-74.
5. Storelli MM, Stuffler RG, and Marcotrigiano GO. (2002). Total and methylmercury residues in tuna-fish from the Mediterranean sea.
6. Food Addit Contam 19(8):715-20.
7. Sunderland EM. (2007). Mercury exposure from domestic and imported estuarine and marine fish in the U.S. seafood market. Environ Health Perspect 115:235-242.
Related Topics:
Technorati Tags: tuna, mercury, toxins, environment, health-and-wellness
FULL STORY:
Like all environmental toxins, mercury can be found in great variety of locations and amounts. Some oceans are lined with ores that contain natural mercury deposits. The Mediterranean Sea, for example, contains cinnabar (mercury sulfide) deposits that can leech into the water and find their way into Mediterranean fish. Tuna from the Mediterranean tends to be higher in mercury than tuna from the Atlantic or the Pacific for this reason.Human activities, however, can be an equally significant source of mercury contamination. Over 100 tons of mercury are released annually into the air by U.S. industries - primarily coal-fired power plants, municipal waste combustion facilities, and incinerators that handle medical waste. Mercury also finds it way into landfills across the country in the form of fluorescent light bulbs, thermostats, and electrical components (including components still used in automobiles).
Once deposited in the soil or in the air, mercury can be transported by natural ecological forces to groundwater, rivers, and oceans. This movement of toxins through our environment (along pathways called "transfer vectors") can bring mercury into the natural habitat of fish thousands of miles away from the original site of contamination.
When it comes to canned light tuna, a good ballpark guideline for safe mercury intake can be based on body weight alone. For every 10 pounds of weight, allow yourself just under one ounce (technically, 0.95 ounces) of canned light tuna per week. If you weigh 150 lbs., for example, limit yourself to 14 ounces (or approximately 2 cans) of tuna. For canned albacore tuna, however, this restriction becomes much greater, because canned albacore averages substantially more mercury than canned light. With albacore, for every 10 pounds of weight, allow yourself only 1/3rd of an ounce per week. In this case, if you weigh 150 pounds, restrict yourself to 5 ounces (less than one can) per week.
While body weight can give you an initial ballpark estimate for restricting your canned fish intake, it's important to note that your body and your lifestyle are unique. You may have other important sources of mercury exposure, and you may have unique metabolic needs when it comes to detoxification of mercury inside your cells. For these reasons, a truly personalized assessment of your mercury exposure and mercury risk can be helpful for planning your fish intake (and other dietary decisions as well).
Several health organizations, including the U.S. Environmental Protection Agency (EPA), have issued advisories cautioning pregnant women (and women considering pregnancy) against excess consumption of mercury-containing fish. For the latest EPA advisory, click here.
References:
1. Adams DH. (2004). Total mercury levels in tunas from offshore waters of the Florida Atlantic coast. Mar Pollut Bulletin 49(7-8):659-63.
2. Hood, E. (2003). A diet rich in fish. High-end consumers face more mercury risks. Environ Health Perspect 111(4):A233.
3. Kraepiel AM, Keller K, Chin HB et al. (2003). Sources and variations of mercury in tuna. Environ Sci Technol 37(24):5551-8.
4. Schober SE, Sinks TH, Jones RL, et al. (2003). Blood mercury levels in US children and women of childbearing age, 1999- 2000. JAMA 289(13):1667-74.
5. Storelli MM, Stuffler RG, and Marcotrigiano GO. (2002). Total and methylmercury residues in tuna-fish from the Mediterranean sea.
6. Food Addit Contam 19(8):715-20.
7. Sunderland EM. (2007). Mercury exposure from domestic and imported estuarine and marine fish in the U.S. seafood market. Environ Health Perspect 115:235-242.
Related Topics:
Technorati Tags: tuna, mercury, toxins, environment, health-and-wellness
Labels: toxins
4 Comments:
I was changing two burned out spiral fluorescent bulbs in an enclosed light fixture in my hallway. When I unscrewed the globe cover on the fixture and took it off I experienced an immediate reaction to something like a gas or vapor that affected my nose, throat, and bronchial membranes with an instant burning and feeling of sucking the air out of me. It sent me to the floor and took a few minutes for me to recover from that initial reaction. Almost instantly I began developing respiratory/sinus problems due to the burning sensations to the membranes in my nose/throat area and oddly the bones in my face. They felt like they could burst with extreme pain. Could this have been due to a build up of a gas/vapor from the two butned out fluorescent bulbs in the enclosed fixture that escaped when I removed the sealed cover? (there was not any dust in the fixture) Over the next couple days, the respiratory/sinus developed in to a full blown infection and the bones in my face were still very painful. The bulbs had both burned out within a week of each other after lasting nearly four years and were not broken unless there was a crack I did not see. I just know that as soon as I removed the cover to the fixture, I was hit with some sort of gas/vapor or something that affected my breathing instantly. What are the hazards and symptoms of exposure to Mercury? Are there any other gases etc. that are in these bulbs? After this happened,I just read about the Mercury in them and they hazards if the bulbs get broken, but as I said, these did not appear to be broken or cracked.
I sougnt medical attention at an ER the next day, but the PA treated me for a sinus infection and sent me home with an antibiotic. Over the next three days I continued to worsen with fever and breathing difficulties and sought medical attention again and was able to get some relief at least from the fever and aching in my facial bones, but am still having problems. I think everyone thought I was crazy to think I had been exposed to something from the bulbs since they didn't appear to be broken. I just know what instantly happened when I dropped the cover to remove the bulbs. I even wrapped the bulbs and took them with me to the ER the first time thinking they would want to check them to see what I may have been exposed to...they threw them away without taking them out of the wrapping saying that couldn't be my problem. Since I am still having effects from whatever hit me, I am seeking any kind of information as to what this may have been, could it have built up in the enclosed fixture, and what are the symptoms and effects of this kind of exposure if it was from the Mercury etc.?
Joy - If both bulbs went out at about the same time your light most likely had a ballast problem and not a bulb problem. If the bad ballast in your light was very old it could have had PCBs or Polychlorinated biphenyls which are very toxic. I don't know if exposure to PCBs causes the side effects that you have experienced, but this seems to me to be the most logical explaination. Best of luck.
I would like to find more information regarding diagnosing / effects and treating of mercury / heavy metal poisoning if anyone could assist, I would be gratefull
My grandson broke a thermometer and handled the mercury bubble before he advised me of the accident. Should I take him to the hospital? What could happen to him if I fail to act. I put the thermometer in a zip loc baggie and will dispose of it as hazardous waste. I am worried about his health. Thanks
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