Dental History
February 17, 2004 10:53 PM Subscribe
Dental History. Anesthesia was discovered by dentists (attributed to Horace Wells and William Morton). Gold filling has been in use since the 15th century.
I looked but could not find the history of silver (mercury) fillings and how mercury in your mouth for years results in heavy metal poisoning but the dental practice is in a Tobacco-industry-like denial for fear of opening a can of class action lawsuits. Lots of good stuff on that topic.
Good luck with your wisdom teeth tboz.
posted by stbalbach at 11:35 PM on February 17, 2004
Good luck with your wisdom teeth tboz.
posted by stbalbach at 11:35 PM on February 17, 2004
Which has been around longer: gold fillings or the magazines in my dentist's office?
posted by bdk3clash at 12:06 AM on February 18, 2004
posted by bdk3clash at 12:06 AM on February 18, 2004
I usually avoid dentists as long as possible, but this site is great! I had no idea dentistry had such history:
"Toothpaste was used as long ago as 500 BC in China and India." (source)
posted by roel at 1:18 AM on February 18, 2004
"Toothpaste was used as long ago as 500 BC in China and India." (source)
posted by roel at 1:18 AM on February 18, 2004
stbalbach-
If the mercury in dental amalgams was really an issue, then those who handle the stuff on a daily basis would be the most likely to suffer deleterious effects. Also, no one in the dental profession would really care if amalgam was banned, becaused that would leave only two options for restorations- composites, which cost 50-100% more, or gold/porcelain indirects which can be as much as a 1000% more. Dental amalgam is a durable, long-lasting material that is also extremely cost-efficient. It has helped to keep the costs of dental care down.
posted by drstrangelove at 5:58 AM on February 18, 2004
If the mercury in dental amalgams was really an issue, then those who handle the stuff on a daily basis would be the most likely to suffer deleterious effects. Also, no one in the dental profession would really care if amalgam was banned, becaused that would leave only two options for restorations- composites, which cost 50-100% more, or gold/porcelain indirects which can be as much as a 1000% more. Dental amalgam is a durable, long-lasting material that is also extremely cost-efficient. It has helped to keep the costs of dental care down.
posted by drstrangelove at 5:58 AM on February 18, 2004
Right. Mercury ios not bad: that is whyu we now toss the oled fashioned thermometers and replace with digital. I was told to do this so my kids would not by accident get the mercury.
Wisodom teeth? tomorrrow I need two crowns removed to get surgery on gums and then replace with new crowns and also a filling. The dentist will own my house.
posted by Postroad at 6:26 AM on February 18, 2004
Wisodom teeth? tomorrrow I need two crowns removed to get surgery on gums and then replace with new crowns and also a filling. The dentist will own my house.
posted by Postroad at 6:26 AM on February 18, 2004
Interesting site, but I have to correct the misconception that Morton and Wells discovered anesthesia. The first anesthetic was given on March 30, 1842 by Crawford Long in Jefferson, GA. Although he didn't publicize his work as well as the two Bostonians, Long is recognised by the American Society of Anesthesiolgists as the discoverer of anesthesia; this event is commemmorated as Doctors Day each year. More on the history of anesthesia here. This is a good book about Morton and Wells, although it does give Long short shrift.
Also, drstrangelove is correct about mercury amalgam; those who oppose it tend to be junk scientists.
posted by TedW at 6:29 AM on February 18, 2004
Also, drstrangelove is correct about mercury amalgam; those who oppose it tend to be junk scientists.
posted by TedW at 6:29 AM on February 18, 2004
Of course, dentists particularly revere Dr. Stanley Bronstein of Montclair, N.J., who invented the incomprehensible modern billing system used by all dentists, in which each visit inevitably costs X, where X equals what your insurance will remburse PLUS the largest amount you are willing to spend rather than walk around with excruciating tooth pain.
posted by Slagman at 7:25 AM on February 18, 2004
posted by Slagman at 7:25 AM on February 18, 2004
Here is the nature of the mercury debate:
The issue is not if mercury is a toxin, but if the amount of mercury in amalgam fillings is enough to be toxic and contribute to illness in humans. The American Dental Association and the majority of dentists believe that the amount of mercury that leaches out from amalgams over a person's lifetime does not pose a health risk
So really the ADA admits you will indeed get mercury in your system by having mercury fillings. However, they don't think the amount is enough to be a problem. Some people think otherwise. Just in the last few years the government thresholds for acceptable mercury levels has been lowered in light of new studies of how toxic mercury is. IMO govt guidelines are always politically charged and the real truth is probably much worse. I don't trust the ADA and what it thinks are acceptable levels of mercury in my system.
posted by stbalbach at 9:07 AM on February 18, 2004
The issue is not if mercury is a toxin, but if the amount of mercury in amalgam fillings is enough to be toxic and contribute to illness in humans. The American Dental Association and the majority of dentists believe that the amount of mercury that leaches out from amalgams over a person's lifetime does not pose a health risk
So really the ADA admits you will indeed get mercury in your system by having mercury fillings. However, they don't think the amount is enough to be a problem. Some people think otherwise. Just in the last few years the government thresholds for acceptable mercury levels has been lowered in light of new studies of how toxic mercury is. IMO govt guidelines are always politically charged and the real truth is probably much worse. I don't trust the ADA and what it thinks are acceptable levels of mercury in my system.
posted by stbalbach at 9:07 AM on February 18, 2004
And TedW, I defiantly don't trust Stephen Barret of QuackWatch
posted by stbalbach at 9:38 AM on February 18, 2004
posted by stbalbach at 9:38 AM on February 18, 2004
"If the mercury in dental amalgams was really an issue, then those who handle the stuff on a daily basis would be the most likely to suffer deleterious effects."
drstrangelove - I consider stbalbach a fairly skeptical person, and not inclined to cultish, unsubstantiated beliefs. I'm with him on this one.
Mercury Exposure of Dentists and [ Dental] Assistants - this little gem cites about 50 different studies. It's worth look. The World Health Organization, further, cites mercury-amalgam fillings as a health risk.
Further - Are Dentists really Healthy? :
"Dentists have:
Twice the rate of Glioblastoma than the rest of the population
Twice the suicide and divorce rate
IQ, Psychomotor, Psycho-emotional tests less than average compared to the rest of the population
Impaired Fine Motor Skills
Of all dentists who currently have a long-term disability, 20% are away from their practice because of a mental or nervous problem."
Now, establishing whether or not the dental profession actually has an elevated level of suicides as compared to other specialties in the medical professions is a very dodgy affair ( see The Straight Dope" on this ) for a number of reasons. But - per my previous links - Dentists don't seem to be an especially healthy lot, and do tend to have elevated mercury levels. mercury is associated with (among many other maladies) depression - it has a powerfully toxic effect on the central nervous system and the brain. So it wouldn't be at all surprising if dentists were especially suicidal.
There are, further, many different pathways by which mercury can leach out of mercury amalgam fillings - oxidation, abrasion, various types of corrosion, battery effects (the loss of ions), etc. The short of it is that mercury-amalgam fillings in the human mouth WILL inevitably leach mercury, and - as far as I am concerned - the ADA is full of shit and running scared from the potential liabilities of it's decades of denial of mercury amalgam risks.
Bastards. Mercury is no joke.
posted by troutfishing at 1:22 PM on February 18, 2004
drstrangelove - I consider stbalbach a fairly skeptical person, and not inclined to cultish, unsubstantiated beliefs. I'm with him on this one.
Mercury Exposure of Dentists and [ Dental] Assistants - this little gem cites about 50 different studies. It's worth look. The World Health Organization, further, cites mercury-amalgam fillings as a health risk.
Further - Are Dentists really Healthy? :
"Dentists have:
Twice the rate of Glioblastoma than the rest of the population
Twice the suicide and divorce rate
IQ, Psychomotor, Psycho-emotional tests less than average compared to the rest of the population
Impaired Fine Motor Skills
Of all dentists who currently have a long-term disability, 20% are away from their practice because of a mental or nervous problem."
Now, establishing whether or not the dental profession actually has an elevated level of suicides as compared to other specialties in the medical professions is a very dodgy affair ( see The Straight Dope" on this ) for a number of reasons. But - per my previous links - Dentists don't seem to be an especially healthy lot, and do tend to have elevated mercury levels. mercury is associated with (among many other maladies) depression - it has a powerfully toxic effect on the central nervous system and the brain. So it wouldn't be at all surprising if dentists were especially suicidal.
There are, further, many different pathways by which mercury can leach out of mercury amalgam fillings - oxidation, abrasion, various types of corrosion, battery effects (the loss of ions), etc. The short of it is that mercury-amalgam fillings in the human mouth WILL inevitably leach mercury, and - as far as I am concerned - the ADA is full of shit and running scared from the potential liabilities of it's decades of denial of mercury amalgam risks.
Bastards. Mercury is no joke.
posted by troutfishing at 1:22 PM on February 18, 2004
Fine- ban amalgams, but please don't complain when a basic filling winds up costing more than you last remembered. Composites aren't exactly kind to living cells, either, which would really only leave gold (since porcelain would require the use of a resin cement and bonding agent.) There is not a cost-efficent way to produce these things, so your average filling could end up costing too much to provide a minimal level of care.
I know all of this, by the way, because I'm a dentist. I tend to be very skeptical, too, but I just don't see a good replacement for amalgam in the near future. The research I've read doesn't support a total ban of the stuff, although I admit that the tide is finally turning against the material.
Finally, there could be other reasons for why we have mental/nervous problems. Unless you're a dentist, you'd probably think that I'm whining when I say this, but this is a tough job. If I wasn't up to my eyeballs in debt ($500,000 total, from student loans and my practice loan) I'd quit tomorrow. It's a fucking thankless job, and several of my friends (who are dentists) are on their way to substance abuse problems. It's also tiring. Mentally and physically, it's demanding. At the end of the day, my fine motor skills are also a little impaired. And, again, unless you are a dentist, you probably wouldn't understand why suicide starts looking pretty good after a long day...
posted by drstrangelove at 4:10 PM on February 18, 2004
I know all of this, by the way, because I'm a dentist. I tend to be very skeptical, too, but I just don't see a good replacement for amalgam in the near future. The research I've read doesn't support a total ban of the stuff, although I admit that the tide is finally turning against the material.
Finally, there could be other reasons for why we have mental/nervous problems. Unless you're a dentist, you'd probably think that I'm whining when I say this, but this is a tough job. If I wasn't up to my eyeballs in debt ($500,000 total, from student loans and my practice loan) I'd quit tomorrow. It's a fucking thankless job, and several of my friends (who are dentists) are on their way to substance abuse problems. It's also tiring. Mentally and physically, it's demanding. At the end of the day, my fine motor skills are also a little impaired. And, again, unless you are a dentist, you probably wouldn't understand why suicide starts looking pretty good after a long day...
posted by drstrangelove at 4:10 PM on February 18, 2004
drstrangelove
Having been the victim of bad dentists, I can only say that I finally have a good one, and when you have a good one, you know it. All kidding aside about the billing issues which are 99 percent the fault of insurers. I can see how it would be a tough job.
posted by Slagman at 8:36 PM on February 18, 2004
Having been the victim of bad dentists, I can only say that I finally have a good one, and when you have a good one, you know it. All kidding aside about the billing issues which are 99 percent the fault of insurers. I can see how it would be a tough job.
posted by Slagman at 8:36 PM on February 18, 2004
stbalbach,
It is unfortunate that you chose troll this FPP to rehash your anti-amalgam, pro-holistic agenda. Dental history is fascinating and would have made for an excellent discussion. I don't think that this is the debate tboz was anticipating when he posted this excellent FPP.
There is no credible evidence that dental amalgam fillings increase the chances of any disease. There is a lot of evidence, however, that suggests amalgam is a cheap, easy to work with and relatively safe alternative to more expensive materials. It is a shame that quacks and perpetrators of health fraud continue to spread misinformation about amalgam in their attempts to profit from fear.
With regards to the suicide rates of dentists, I will side with drstrangelove - dentistry is physically, mentally and emotionally taxing. Performing fine motor actions with arms completely unsupported and your back at an unnatural angle for extended periods of time is hard, manual labor. Throw into the mix patients who only come in when it starts hurting (and when it's usually too late) but blame their dentist for their own carelessness, patients who casually skip appointments but want to be seen immediately on the drop of a dime when they can no longer bear the pain or patients who come to the dentists without even bothering to brush their teeth with huge pieces of lunch/breakfast stuck between their teeth and you have a recipe for substance abuse or worse. Oh yeah, did I mention the child patients who are absolutely terrified because their mothers always threaten them with painful horror in the dental office if they don't brush their teeth even though painless dentistry is now the norm?
My hat is off to drstrangelove for his determination and his strength of will and I have no patience for health fraud quacks who try to make drstrangelove's job any harder.
posted by cup at 10:40 PM on February 20, 2004
It is unfortunate that you chose troll this FPP to rehash your anti-amalgam, pro-holistic agenda. Dental history is fascinating and would have made for an excellent discussion. I don't think that this is the debate tboz was anticipating when he posted this excellent FPP.
There is no credible evidence that dental amalgam fillings increase the chances of any disease. There is a lot of evidence, however, that suggests amalgam is a cheap, easy to work with and relatively safe alternative to more expensive materials. It is a shame that quacks and perpetrators of health fraud continue to spread misinformation about amalgam in their attempts to profit from fear.
With regards to the suicide rates of dentists, I will side with drstrangelove - dentistry is physically, mentally and emotionally taxing. Performing fine motor actions with arms completely unsupported and your back at an unnatural angle for extended periods of time is hard, manual labor. Throw into the mix patients who only come in when it starts hurting (and when it's usually too late) but blame their dentist for their own carelessness, patients who casually skip appointments but want to be seen immediately on the drop of a dime when they can no longer bear the pain or patients who come to the dentists without even bothering to brush their teeth with huge pieces of lunch/breakfast stuck between their teeth and you have a recipe for substance abuse or worse. Oh yeah, did I mention the child patients who are absolutely terrified because their mothers always threaten them with painful horror in the dental office if they don't brush their teeth even though painless dentistry is now the norm?
My hat is off to drstrangelove for his determination and his strength of will and I have no patience for health fraud quacks who try to make drstrangelove's job any harder.
posted by cup at 10:40 PM on February 20, 2004
cup - Your rhetoric is so dismissively over the top that I just have to post this (the numbers refer to footnoted studies. the entire report with footnotes is here) :
"1. Dental offices are known to be one of the largest users of inorganic mercury (71b,26,etc.). It is well documented that dentists and dental personnel who work with amalgam are chronically exposed to mercury vapor, which accumulates in their bodies to much higher levels than for most non-occupationally exposed. Adverse health effects of this exposure including subtle neurological effects have also been well documented that affect most dentists and dental assistants, with measurable effects among those in the lowest levels of exposure. Mercury levels of dental personnel average at least 2 times that of controls for hair (397-401), urine (25d,57,64,69,99,123,124,138,171,173,222,249, 290,362,397-399) and for blood (124,195,253,249,397).
Sweden, which voted to ban use of mercury in fillings, is the country with the most exposure and health effects studies regarding amalgam, and urine levels in dental professionals from Swedish and European studies ranged from 0.8 to 30.1 ug/L with study averages from 3.7 to 6.2 ug/L (124,172,253,64,68). The Swedish safety guideline for mercury in urine is 5.6 nmol Hg/nmol(11.6 ug/L).
Study averages for other countries ranged from 3.3 to 36 microgram/liter (ug/L)(69,70,171,290,397). A large survey of dentists at the Norwegian Dental Assoc. meeting (171) found that the mean mercury level in 1986 was 7.8 ug/L with approx. 16% above 13.6ug/L, and for 1987 found an average of 8.6 ug/L with approx. 15% above 15.8 ug/L, with women having higher levels than men in general.
A U.S. national sample of dentists provided by the American Dental Association had an average of 5.2 ug/L (70,290). In that large sample of dentists, 10% of dentists had urine mercury levels over 10.4 ug/L and 1% had levels over 33.4ug/L (290,25c), indicating daily exposure levels of over 100 ug/day. Mercury excretion levels were found to have a positive correlation with the number of amalgams placed or replaced per week, the number of amalgams polished each week, and with the number of fillings in the dentist (171,172,173). In one study, each filling was found to increase mercury in the urine approx. 3%, though the relationship was nonlinear and increased more with larger number of fillings (124).
Much higher accumulated body burden levels in dental personnel were found based on challenge tests than for controls (303), with excretion levels after a dose of a chelator as high as 10 times the corresponding levels for controls (57,69,290,303).
Autopsy studies have found similar high body accumulation in dental workers, with levels in pituitary gland and thyroid over 10 times controls and levels in renal cortex 7 times controls (99,363,38). Autopsies of former dental staff found levels of mercury in the pituitary gland averaged as high as 4,040 ppb. They also found much higher levels in the brain occipital cortex (as high as 300 ppb), renal cortex (as high as 2110 ppb) and thyroid (as high as 28,000 ppb. In general dental assistants and women dental workers showed higher levels of mercury than male dentists (171,172,173,253,303,362).
Mercury levels in blood of dental professionals ranged from 0.6 to 57 ug/L, with study averages ranging from 1.34 to 9.8 ug/L (124,195,253,249,531). A review of several studies of mercury level in hair or nails of dentists and dental workers found median levels were 50 to 300% more than those of controls (38, p287-288,& 10,16,178,531). Dentists have been found to have elevated skeletal mercury levels, which has been found to be a factor in osteoporosis, as well as mercury retention and kidney effects that tend to cause lower measured levels of mercury in urine tests (258). A group of dental students taking a course involving work with amalgam had their urine tested before and after the course was over. The average urine level increased by 500% during the course (63). Allergy tests given to another group of dental students found 44% of them were allergic to mercury (156). Studies have found that the longer time exposed, the more likely to be allergic and the more effects (6b,154c,156,503a) . One study found that over a 4 year period of dental school, the sensitivity rate increased 5 fold to over 10% (154c). Another group of dental students had similar results (362), while another group of dental student showed compromised immune systems compared to medical students. The total lymphocyte count, total T cell numbers (CD3), T helper/ inducer(CD4+CD8-), and T suppressor/cytotoxic(CD4-CD8+) numbers were significantly elevated in the dental students compared to the matched control group (408). Similar results have been seen in other studies as well (408).
Urinary porphyrin profiles were found to be an excellent biomarker of level of body mercury level and mercury damage neurological effects, with coproporphyrin significantly higher in those with higher mercury exposure and urine levels (70,260). Coproporphyrin levels have a higher correlation with symptoms and body mercury levels as tested by challenge test (69,303), but care should be taken regarding challenge tests as the high levels of mercury released can cause serious health effects in some, especially those who still have amalgam fillings or high accumulations of mercury. Screening test that are less burdensome and less expensive are now available as first morning void urine samples have been found to be highly correlations to 24 hour urine test for mercury level or porphyrins (73).
2. The average dental office exposure affects the body mercury level at least as much as the workers on fillings (57,64,69,123,138,171,173,303), with several studies finding levels approximately the same as having 19 amalgam fillings (123,124,173). Many surveys have been made of office exposure levels (1,6,7,10, etc.) The level of mercury at breathing point in offices measured ranged form 0.7 to over 300 micrograms per cubic meter (ug/M3) (120,172,253,249). The average levels in offices with reasonable controls ranged from 1.5 to 3.6 ug/M3, but even in Sweden which has had more office environmental controls than others spot levels of over 150 ug/M3 were found in 8 offices (172). Another study found spot readings as high as 200 ug/M3 in offices with few controls that only used saliva extractor (120). OSHA surveys find 6-16% of U.S. dental offices exceed the OSHA dental office standard of 50 ug/M3, and residual levels in equipment sterilizers often exceed this level (454).
The German workplace mercury standard of 1 ug/M3 is almost always exceeded (258).
The U.S. ATSDR mercury vapor exposure MRL for chronic exposure is much lower, 0.2 ug/M3 (217) (giving approx. 4 ug/day exposure), similar to U.S. EPA and Health Canada guidelines (2,209). Thus most office mercury levels were found to far exceed the U.S. guidelines for chronic mercury exposure.
Use of high speed drill in removal or replacement has been found to create high volume of mercury vapor and respirable particles, and dental masks to only filter out about 40 % of such particles (219,247). Amalgam dust generated by high speed drilling is absorbed rapidly into the blood through the lungs and major organs such as the heart receive a high dose within minutes (219a,395c,503c). This produces high levels of exposure to patient and dental staff. Use of water spray, high velocity evacuation and rubber dam reduce exposure to patient and dental staff significantly, as seen in previous discussion. In addition to these measures researchers also advise all dental staff should wear face masks and patients be supplied with outside air (120,153). Some studies note that carpeting and rugs in dental offices should be avoided as it is a major repository of mercury (6,7,21d,71b,188,395c,503) For office's using an aspirator, at the dentist's breathing zone, mercury vapor concentrations of ten times the current occupational exposure limit of 25 microg/m3 were recorded after 20 minutes of continuous aspirator operation (219). A build up of amalgam contamination within the internal corrugated tubing of the aspirator was found to be the main source of mercury vapor emissions followed by particulate amalgam trapped within the vacuum motor. As the vacuum motor heated up with run time, mercury vapor emissions increased. It was found that the bacterial air exhaust filter (designed to clean the contaminated waste air entering the surgery) offered no protection to mercury vapor. Use of such measures along with a Clean-UpTM aspirator tip was found to reduce exposure to patient and staff approximately 90% (397).
3. Dentists were found to score significantly worse than a comparable control group on neurobehavioral tests of motor speed, visual scanning, and visuomotor coordination (69,70,123,249,290,395,531,1b), concentration, verbal memory, visual memory (68,69,70,249,290,395,531,1b), and emotional/mood tests (70,249,290,395,1b). Test performance was found to be proportional to exposure/body levels of mercury (68,70,249,290,395,1b). Significant adverse neurobehavioral effects were found even for dental personnel receiving low exposure levels (less than 4 ug/l Hg in urine)(290). This study was for dental personnel having mercury excretion levels below the 10th percentile of the overall dental population. Such levels are also common among the general population of non- dental personnel with several fillings. This study used a new methodology which used standard urine mercury levels as a measure of recent exposure, and urine levels after chelation with a chemical, DMPS, to measure body burden mercury levels. Thirty percent of dentists with more than average exposure were found to have neuropathies and visuographic dysfunction (395). Mercury exposure has been found to often cause disability in dental workers (230b,395c,503,504a, etc.)
Chelators like DMPS have been found after a fast to release mercury from cells in tissue to be available for excretion. This method was found to give enhanced precision and power to the results of the tests and correlations. Even at the low levels of exposure of the subjects of this study, there were clear demonstrated differences in test scores involving memory, mood, and motor skills related to the level of exposure pre and post chelation (290). Those with higher levels of mercury had deficits in both memory, mood, and motor function compared to those with lower exposure levels. And the plotted test results gave no indication of there existing a threshold below effects were not measurable. Mood scores including anger were found to correlate more strongly with pre chelation urine mercury levels; while toxicity symptoms, concentration, memory (vocabulary,word), and motor function correlated more strongly with post-chelation mercury levels. Another study using DMPS challenge test found over 20 times higher mercury excretion in dentists than in controls, indicating high body burden of mercury compared to controls (491).
Many dentists have been documented to suffer from mercury poisoning (6f,71,72,74,193,246,247,248,369,531) other than the documented neurological effects, such as chronic fatigue, muscle pains, stomach problems, tremors, motor effects, immune reactivity, etc. One of the common effects of chronic mercury exposure is chronic fatigue due to immune system overload and activation. Many studies have found this occurs frequently in dentists and dental staff along with other related symptoms- lack of ability to concentrate, chronic muscular pain, burnout, etc.(249,369,377,378,490,531,1b). In a group of dentists and dental workers suffering from extreme fatigue and tested by the immune test MELISA, 50% had autoimmune reaction to inorganic mercury and immune reactions to other metals used in dentistry were also common (369). Tests of controls did not find such immune reactions common. In another study nearly 50 % of dental staff in a group tested had positive autoimmune ANA titers compared to less than 1 % of the general population (35).
One dentist with severe symptoms similar to ALS improved after treatment for mercury poisoning (246), and another with Parkinson's disease recovered after reduction of exposure and chelation (248). Similar cases among those with other occupational exposure have been seen. A survey of over 60,000 U.S. dentists and dental assistants with chronic exposure to mercury vapor and anesthetics found increased health problems compared to controls, including significantly higher liver, kidney, and neurological diseases (99,193). A recent study in Scotland found similar results (531). Other studies reviewed found increased rates of brain cancer and allergies (99,193). Swedish male dentists were found to have an elevated standardized mortality ratio compared to other male academic groups (284). Dental workers and other workers exposed to mercury vapor were found to have a shortening of visual evoked potential latency and a decrease in amplitude, with magnitudes correlated with urine excretion levels (190). Dentists were also found to have a high incidence of radicular muscular neuralgia and peripheral sensory degradation (190,395,490). In one study of dentists and dental assistants, 50% reported significant irritability, 46% arthritic pains, and 45% headaches (490a), while another study found selective atrophy of muscle fibre in women dental workers (490b). In a study in Brazil(492), 62% of dental workers had urine mercury levels over 10 mg/L, and indications of mild to moderate mercury poisoning in 62% of workers. The most common problems were related to the central nervous system.
4. Both dental hygienists and patients get high doses of mercury vapor when dental hygienists polish or use ultrasonic scalers on amalgam surfaces (240,400,503c). Pregnant women or pregnant hygienist especially should avoid these practices during pregnancy or while nursing since maternal mercury exposure has been shown to affect the fetus and to be related to birth defects, SIDS, etc.(10,23,31c,37,38,110,142,146,401,19,31,50). Amalgam has been shown to be the main source of mercury in most infants and breast milk, which often contain higher mercury levels than in the mother's blood (20,61,112,186,287). Because of high documented exposure levels when amalgam fillings are brushed (182,222,348) dental hygienist are advised not to polish dental amalgams when cleaning teeth. Face masks worn by dental workers filter out only about 40% of small dislodged amalgam particles from drilling or polishing, and very little mercury vapor (247). Dental staff have been found to have significantly higher prevalence of eye problems, conjunctivitis, atopic dermatitis, and contact urticaria (247,156,74).
An epidemiological survey conducted in Lithuania on women working in dental offices (where Hg concentrations were < 80 ug/M3) had increased incidence of spontaneous abortions and breast pathologies that were directly related to the length of time on the job (277a). A large U.S. survey also found higher spontaneous abortion rate among dental assistants and wives of dentists (193), and another study found an increased risk of spontaneous abortions and other pregnancy complications among women working in dental surgeries (277b). A study of dentist and dental assistants in the Netherlands found 50% higher rates of spontaneous abortions, stillbirths, and congenital defects than for the control group (394), with unusually high occurrence of spina bifida. A study in Poland also found a significant positive association between mercury levels and occurrence of reproductive failures and menstrual cycle disorders, and concluded dental work to be an occupational hazard with respect to reproductive processes (401).
5. Body burden increases with time and older dentists have median mercury urine levels about 4 times those of controls, as well as higher brain and body burdens (1,34, 68-74,99), and poor performance on memory tests (68, 69,70,249,290) Some older dentists have mercury levels in some parts of the brain as much as 80 times higher than normal levels (14,34,99). Dentists and dental personnel experience significantly higher levels of neurological, memory, musculoskeletal, visiomotor, mood, and behavioral problems, which increase with years of exposure (1,34,68-73,88,123,188,246,247,248,249,290,395). Even dental personnel with relatively low exposure (urine Hg<4 ug/l) were found to have significant neurological effects (290) and was found to be correlated with body burden of mercury. Most studies find dentists have increased levels of irritability and tension (1,490,504b), high rates of drug dependancy and disability due to psychological problems (15,1b), and higher suicide rates than the general white population (284,493,1b), but one study found rates in same range as doctors.
6. Female dental technicians who work with amalgam tend to have increased menstrual disturbances (275,401,10,38), significantly reduced fertility and lowered probability of conception (10,24,38,121), increased spontaneous abortions (10,31,38,277,433), and their children have significantly lower average IQ compared to the general population (1,279,541,38,110). Populations with only slightly increased levels of mercury in hair had decreases in academic ability (3). Effects are directly related to length of time on the job (277). The level of mercury excreted in urine is significantly higher for female dental assistants than dentists due to biological factors (171,172,173,247,124a). Several dental assistants have been diagnosed with mercury toxicity and some have died of related health effects (32,245,246,247,248). From the medical register of births since 1967 in Norway, it can be seen that dental nurse/assistants have a clearly increased risk of having a deformed child or spontaneous abortion (433). Female dentists have increased rates of spontaneous abortion and perinatal mortality (193,38,10,433)),compared to controls. A study in Poland found a much higher incidence of birth defects among female dentist and dental assistants than normal (10). A chronically ill dental nurse diagnosed with mercury sensitivity recovered after replacement of fillings and changing jobs (60), and a female dentist recovered from Parkinson's after mercury detox (248). Some studies have found increased risk of lung, kidney, brain, and CNS system cancers among dental workers (14,34,99,143,283).
7. Many homes of dentists have been found to have high levels of mercury contamination used by dentists bringing mercury home on shoes and clothes(188).
8. Nationwide the dental industry is the third largest user of mercury, using over 45 tons of mercury per year (26), and most of this mercury eventually ends up in the environment. Amalgam from dental offices is by far the largest contributor of mercury into sewers and sewer plants (84,13b,19,26), with mercury from replaced amalgam fillings and crown bases the largest source. As much as 10% of prepared new amalgam becomes waste. This mercury also accumulates in building sewer pipes and septic tanks or drain fields where used, creating toxic liabilities. Unlike most European countries and Canada which have much more stringent regulation of mercury that requires amalgam separators in dental offices (26,28,42), the U.S. does not and most dental offices do not have them. The discharge into sewers at a dental office per dentist using amalgam without amalgam separators is between 270 and 570 milligrams per day (84,26). For the U.S. with approximately 170,000 dentists working with amalgam (26), this would be approximately 16,000 kg/yr (or slightly over 16 tons/year of mercury into sewers and thus into streams, lakes, bays, and sewer sludge. In Canada the annual amount discharged is about 2 tons per year (28), with portions ending up in waters/fish, some in landfills and cropland, and in air emissions. The recently enacted regulations on dental office waste are expected to reduce emissions by at least 63% by 2005, compared to 2000 (28).
A study in Michigan estimated that dental mercury is responsible for approximately 14 % of mercury discharged to streams (85). An EPA study (13) found that dental office waste were responsible for similar levels of mercury in lakes, bays, and streams in other areas throughout the U.S. A Canadian study found similar levels of mercury contribution from dental offices into lakes and streams, and surveys of dental office disposal practices found the majority violated disposal regulations, and dangerous levels of mercury are accumulating in pipes and septic tanks from many offices(19,41,26).
The total discharge into sewers from dental amalgam at individual homes and businesses is almost as large as that from dental offices, since the average person with amalgam fillings excretes in body waste approx. 100 micrograms per day of mercury (86,87,89,520). This has also been confirmed by medical labs (13c), such as Doctors Data Lab in Chicago and Biospectron in Sweden, which do thousands of stool tests per year and is consistent with studies measuring levels in residental sewers by municipalities (13b). In the U.S. this would amount to approximately 7300 kilograms per year into sewers or over 8 tons per year. Thus the amount of mercury being excreted from dental amalgam is more than enough to cause dangerous levels of mercury in fish in most U.S. streams into which sewers empty. Studies by Oak Ridge National Laboratory (U.S. Dept. of Energy) and other studies have confirmed high levels of mercury in sewers and sewer sludge (42,43). According to an EPA study the majority of U.S. sewerage plants cannot meet the new EPA guideline for mercury discharge into waterways that was designed to prevent bioaccumulation in fish and wildlife due to household sewer mercury levels (15,13). Over 3 tons of mercury flows into the Chesapeake Bay annually from sewer plants, with numerous resulting fish consumption advisories for that area and similar for other areas (17). The EPA discharge rule had been reduced due to a National Academy of Sciences report of July 2000 that found that even small levels of mercury in fish result in unacceptable risks of birth defects and developmental effects in infants (18)."
Shall I go on ? Mercury is highly toxic. It's in our mouths, and there are many diference types of pathways for amalgam-bound mercury to be released into the human body.
This is not really a profound tale.
posted by troutfishing at 9:00 PM on February 23, 2004
"1. Dental offices are known to be one of the largest users of inorganic mercury (71b,26,etc.). It is well documented that dentists and dental personnel who work with amalgam are chronically exposed to mercury vapor, which accumulates in their bodies to much higher levels than for most non-occupationally exposed. Adverse health effects of this exposure including subtle neurological effects have also been well documented that affect most dentists and dental assistants, with measurable effects among those in the lowest levels of exposure. Mercury levels of dental personnel average at least 2 times that of controls for hair (397-401), urine (25d,57,64,69,99,123,124,138,171,173,222,249, 290,362,397-399) and for blood (124,195,253,249,397).
Sweden, which voted to ban use of mercury in fillings, is the country with the most exposure and health effects studies regarding amalgam, and urine levels in dental professionals from Swedish and European studies ranged from 0.8 to 30.1 ug/L with study averages from 3.7 to 6.2 ug/L (124,172,253,64,68). The Swedish safety guideline for mercury in urine is 5.6 nmol Hg/nmol(11.6 ug/L).
Study averages for other countries ranged from 3.3 to 36 microgram/liter (ug/L)(69,70,171,290,397). A large survey of dentists at the Norwegian Dental Assoc. meeting (171) found that the mean mercury level in 1986 was 7.8 ug/L with approx. 16% above 13.6ug/L, and for 1987 found an average of 8.6 ug/L with approx. 15% above 15.8 ug/L, with women having higher levels than men in general.
A U.S. national sample of dentists provided by the American Dental Association had an average of 5.2 ug/L (70,290). In that large sample of dentists, 10% of dentists had urine mercury levels over 10.4 ug/L and 1% had levels over 33.4ug/L (290,25c), indicating daily exposure levels of over 100 ug/day. Mercury excretion levels were found to have a positive correlation with the number of amalgams placed or replaced per week, the number of amalgams polished each week, and with the number of fillings in the dentist (171,172,173). In one study, each filling was found to increase mercury in the urine approx. 3%, though the relationship was nonlinear and increased more with larger number of fillings (124).
Much higher accumulated body burden levels in dental personnel were found based on challenge tests than for controls (303), with excretion levels after a dose of a chelator as high as 10 times the corresponding levels for controls (57,69,290,303).
Autopsy studies have found similar high body accumulation in dental workers, with levels in pituitary gland and thyroid over 10 times controls and levels in renal cortex 7 times controls (99,363,38). Autopsies of former dental staff found levels of mercury in the pituitary gland averaged as high as 4,040 ppb. They also found much higher levels in the brain occipital cortex (as high as 300 ppb), renal cortex (as high as 2110 ppb) and thyroid (as high as 28,000 ppb. In general dental assistants and women dental workers showed higher levels of mercury than male dentists (171,172,173,253,303,362).
Mercury levels in blood of dental professionals ranged from 0.6 to 57 ug/L, with study averages ranging from 1.34 to 9.8 ug/L (124,195,253,249,531). A review of several studies of mercury level in hair or nails of dentists and dental workers found median levels were 50 to 300% more than those of controls (38, p287-288,& 10,16,178,531). Dentists have been found to have elevated skeletal mercury levels, which has been found to be a factor in osteoporosis, as well as mercury retention and kidney effects that tend to cause lower measured levels of mercury in urine tests (258). A group of dental students taking a course involving work with amalgam had their urine tested before and after the course was over. The average urine level increased by 500% during the course (63). Allergy tests given to another group of dental students found 44% of them were allergic to mercury (156). Studies have found that the longer time exposed, the more likely to be allergic and the more effects (6b,154c,156,503a) . One study found that over a 4 year period of dental school, the sensitivity rate increased 5 fold to over 10% (154c). Another group of dental students had similar results (362), while another group of dental student showed compromised immune systems compared to medical students. The total lymphocyte count, total T cell numbers (CD3), T helper/ inducer(CD4+CD8-), and T suppressor/cytotoxic(CD4-CD8+) numbers were significantly elevated in the dental students compared to the matched control group (408). Similar results have been seen in other studies as well (408).
Urinary porphyrin profiles were found to be an excellent biomarker of level of body mercury level and mercury damage neurological effects, with coproporphyrin significantly higher in those with higher mercury exposure and urine levels (70,260). Coproporphyrin levels have a higher correlation with symptoms and body mercury levels as tested by challenge test (69,303), but care should be taken regarding challenge tests as the high levels of mercury released can cause serious health effects in some, especially those who still have amalgam fillings or high accumulations of mercury. Screening test that are less burdensome and less expensive are now available as first morning void urine samples have been found to be highly correlations to 24 hour urine test for mercury level or porphyrins (73).
2. The average dental office exposure affects the body mercury level at least as much as the workers on fillings (57,64,69,123,138,171,173,303), with several studies finding levels approximately the same as having 19 amalgam fillings (123,124,173). Many surveys have been made of office exposure levels (1,6,7,10, etc.) The level of mercury at breathing point in offices measured ranged form 0.7 to over 300 micrograms per cubic meter (ug/M3) (120,172,253,249). The average levels in offices with reasonable controls ranged from 1.5 to 3.6 ug/M3, but even in Sweden which has had more office environmental controls than others spot levels of over 150 ug/M3 were found in 8 offices (172). Another study found spot readings as high as 200 ug/M3 in offices with few controls that only used saliva extractor (120). OSHA surveys find 6-16% of U.S. dental offices exceed the OSHA dental office standard of 50 ug/M3, and residual levels in equipment sterilizers often exceed this level (454).
The German workplace mercury standard of 1 ug/M3 is almost always exceeded (258).
The U.S. ATSDR mercury vapor exposure MRL for chronic exposure is much lower, 0.2 ug/M3 (217) (giving approx. 4 ug/day exposure), similar to U.S. EPA and Health Canada guidelines (2,209). Thus most office mercury levels were found to far exceed the U.S. guidelines for chronic mercury exposure.
Use of high speed drill in removal or replacement has been found to create high volume of mercury vapor and respirable particles, and dental masks to only filter out about 40 % of such particles (219,247). Amalgam dust generated by high speed drilling is absorbed rapidly into the blood through the lungs and major organs such as the heart receive a high dose within minutes (219a,395c,503c). This produces high levels of exposure to patient and dental staff. Use of water spray, high velocity evacuation and rubber dam reduce exposure to patient and dental staff significantly, as seen in previous discussion. In addition to these measures researchers also advise all dental staff should wear face masks and patients be supplied with outside air (120,153). Some studies note that carpeting and rugs in dental offices should be avoided as it is a major repository of mercury (6,7,21d,71b,188,395c,503) For office's using an aspirator, at the dentist's breathing zone, mercury vapor concentrations of ten times the current occupational exposure limit of 25 microg/m3 were recorded after 20 minutes of continuous aspirator operation (219). A build up of amalgam contamination within the internal corrugated tubing of the aspirator was found to be the main source of mercury vapor emissions followed by particulate amalgam trapped within the vacuum motor. As the vacuum motor heated up with run time, mercury vapor emissions increased. It was found that the bacterial air exhaust filter (designed to clean the contaminated waste air entering the surgery) offered no protection to mercury vapor. Use of such measures along with a Clean-UpTM aspirator tip was found to reduce exposure to patient and staff approximately 90% (397).
3. Dentists were found to score significantly worse than a comparable control group on neurobehavioral tests of motor speed, visual scanning, and visuomotor coordination (69,70,123,249,290,395,531,1b), concentration, verbal memory, visual memory (68,69,70,249,290,395,531,1b), and emotional/mood tests (70,249,290,395,1b). Test performance was found to be proportional to exposure/body levels of mercury (68,70,249,290,395,1b). Significant adverse neurobehavioral effects were found even for dental personnel receiving low exposure levels (less than 4 ug/l Hg in urine)(290). This study was for dental personnel having mercury excretion levels below the 10th percentile of the overall dental population. Such levels are also common among the general population of non- dental personnel with several fillings. This study used a new methodology which used standard urine mercury levels as a measure of recent exposure, and urine levels after chelation with a chemical, DMPS, to measure body burden mercury levels. Thirty percent of dentists with more than average exposure were found to have neuropathies and visuographic dysfunction (395). Mercury exposure has been found to often cause disability in dental workers (230b,395c,503,504a, etc.)
Chelators like DMPS have been found after a fast to release mercury from cells in tissue to be available for excretion. This method was found to give enhanced precision and power to the results of the tests and correlations. Even at the low levels of exposure of the subjects of this study, there were clear demonstrated differences in test scores involving memory, mood, and motor skills related to the level of exposure pre and post chelation (290). Those with higher levels of mercury had deficits in both memory, mood, and motor function compared to those with lower exposure levels. And the plotted test results gave no indication of there existing a threshold below effects were not measurable. Mood scores including anger were found to correlate more strongly with pre chelation urine mercury levels; while toxicity symptoms, concentration, memory (vocabulary,word), and motor function correlated more strongly with post-chelation mercury levels. Another study using DMPS challenge test found over 20 times higher mercury excretion in dentists than in controls, indicating high body burden of mercury compared to controls (491).
Many dentists have been documented to suffer from mercury poisoning (6f,71,72,74,193,246,247,248,369,531) other than the documented neurological effects, such as chronic fatigue, muscle pains, stomach problems, tremors, motor effects, immune reactivity, etc. One of the common effects of chronic mercury exposure is chronic fatigue due to immune system overload and activation. Many studies have found this occurs frequently in dentists and dental staff along with other related symptoms- lack of ability to concentrate, chronic muscular pain, burnout, etc.(249,369,377,378,490,531,1b). In a group of dentists and dental workers suffering from extreme fatigue and tested by the immune test MELISA, 50% had autoimmune reaction to inorganic mercury and immune reactions to other metals used in dentistry were also common (369). Tests of controls did not find such immune reactions common. In another study nearly 50 % of dental staff in a group tested had positive autoimmune ANA titers compared to less than 1 % of the general population (35).
One dentist with severe symptoms similar to ALS improved after treatment for mercury poisoning (246), and another with Parkinson's disease recovered after reduction of exposure and chelation (248). Similar cases among those with other occupational exposure have been seen. A survey of over 60,000 U.S. dentists and dental assistants with chronic exposure to mercury vapor and anesthetics found increased health problems compared to controls, including significantly higher liver, kidney, and neurological diseases (99,193). A recent study in Scotland found similar results (531). Other studies reviewed found increased rates of brain cancer and allergies (99,193). Swedish male dentists were found to have an elevated standardized mortality ratio compared to other male academic groups (284). Dental workers and other workers exposed to mercury vapor were found to have a shortening of visual evoked potential latency and a decrease in amplitude, with magnitudes correlated with urine excretion levels (190). Dentists were also found to have a high incidence of radicular muscular neuralgia and peripheral sensory degradation (190,395,490). In one study of dentists and dental assistants, 50% reported significant irritability, 46% arthritic pains, and 45% headaches (490a), while another study found selective atrophy of muscle fibre in women dental workers (490b). In a study in Brazil(492), 62% of dental workers had urine mercury levels over 10 mg/L, and indications of mild to moderate mercury poisoning in 62% of workers. The most common problems were related to the central nervous system.
4. Both dental hygienists and patients get high doses of mercury vapor when dental hygienists polish or use ultrasonic scalers on amalgam surfaces (240,400,503c). Pregnant women or pregnant hygienist especially should avoid these practices during pregnancy or while nursing since maternal mercury exposure has been shown to affect the fetus and to be related to birth defects, SIDS, etc.(10,23,31c,37,38,110,142,146,401,19,31,50). Amalgam has been shown to be the main source of mercury in most infants and breast milk, which often contain higher mercury levels than in the mother's blood (20,61,112,186,287). Because of high documented exposure levels when amalgam fillings are brushed (182,222,348) dental hygienist are advised not to polish dental amalgams when cleaning teeth. Face masks worn by dental workers filter out only about 40% of small dislodged amalgam particles from drilling or polishing, and very little mercury vapor (247). Dental staff have been found to have significantly higher prevalence of eye problems, conjunctivitis, atopic dermatitis, and contact urticaria (247,156,74).
An epidemiological survey conducted in Lithuania on women working in dental offices (where Hg concentrations were < 80 ug/M3) had increased incidence of spontaneous abortions and breast pathologies that were directly related to the length of time on the job (277a). A large U.S. survey also found higher spontaneous abortion rate among dental assistants and wives of dentists (193), and another study found an increased risk of spontaneous abortions and other pregnancy complications among women working in dental surgeries (277b). A study of dentist and dental assistants in the Netherlands found 50% higher rates of spontaneous abortions, stillbirths, and congenital defects than for the control group (394), with unusually high occurrence of spina bifida. A study in Poland also found a significant positive association between mercury levels and occurrence of reproductive failures and menstrual cycle disorders, and concluded dental work to be an occupational hazard with respect to reproductive processes (401).
5. Body burden increases with time and older dentists have median mercury urine levels about 4 times those of controls, as well as higher brain and body burdens (1,34, 68-74,99), and poor performance on memory tests (68, 69,70,249,290) Some older dentists have mercury levels in some parts of the brain as much as 80 times higher than normal levels (14,34,99). Dentists and dental personnel experience significantly higher levels of neurological, memory, musculoskeletal, visiomotor, mood, and behavioral problems, which increase with years of exposure (1,34,68-73,88,123,188,246,247,248,249,290,395). Even dental personnel with relatively low exposure (urine Hg<4 ug/l) were found to have significant neurological effects (290) and was found to be correlated with body burden of mercury. Most studies find dentists have increased levels of irritability and tension (1,490,504b), high rates of drug dependancy and disability due to psychological problems (15,1b), and higher suicide rates than the general white population (284,493,1b), but one study found rates in same range as doctors.
6. Female dental technicians who work with amalgam tend to have increased menstrual disturbances (275,401,10,38), significantly reduced fertility and lowered probability of conception (10,24,38,121), increased spontaneous abortions (10,31,38,277,433), and their children have significantly lower average IQ compared to the general population (1,279,541,38,110). Populations with only slightly increased levels of mercury in hair had decreases in academic ability (3). Effects are directly related to length of time on the job (277). The level of mercury excreted in urine is significantly higher for female dental assistants than dentists due to biological factors (171,172,173,247,124a). Several dental assistants have been diagnosed with mercury toxicity and some have died of related health effects (32,245,246,247,248). From the medical register of births since 1967 in Norway, it can be seen that dental nurse/assistants have a clearly increased risk of having a deformed child or spontaneous abortion (433). Female dentists have increased rates of spontaneous abortion and perinatal mortality (193,38,10,433)),compared to controls. A study in Poland found a much higher incidence of birth defects among female dentist and dental assistants than normal (10). A chronically ill dental nurse diagnosed with mercury sensitivity recovered after replacement of fillings and changing jobs (60), and a female dentist recovered from Parkinson's after mercury detox (248). Some studies have found increased risk of lung, kidney, brain, and CNS system cancers among dental workers (14,34,99,143,283).
7. Many homes of dentists have been found to have high levels of mercury contamination used by dentists bringing mercury home on shoes and clothes(188).
8. Nationwide the dental industry is the third largest user of mercury, using over 45 tons of mercury per year (26), and most of this mercury eventually ends up in the environment. Amalgam from dental offices is by far the largest contributor of mercury into sewers and sewer plants (84,13b,19,26), with mercury from replaced amalgam fillings and crown bases the largest source. As much as 10% of prepared new amalgam becomes waste. This mercury also accumulates in building sewer pipes and septic tanks or drain fields where used, creating toxic liabilities. Unlike most European countries and Canada which have much more stringent regulation of mercury that requires amalgam separators in dental offices (26,28,42), the U.S. does not and most dental offices do not have them. The discharge into sewers at a dental office per dentist using amalgam without amalgam separators is between 270 and 570 milligrams per day (84,26). For the U.S. with approximately 170,000 dentists working with amalgam (26), this would be approximately 16,000 kg/yr (or slightly over 16 tons/year of mercury into sewers and thus into streams, lakes, bays, and sewer sludge. In Canada the annual amount discharged is about 2 tons per year (28), with portions ending up in waters/fish, some in landfills and cropland, and in air emissions. The recently enacted regulations on dental office waste are expected to reduce emissions by at least 63% by 2005, compared to 2000 (28).
A study in Michigan estimated that dental mercury is responsible for approximately 14 % of mercury discharged to streams (85). An EPA study (13) found that dental office waste were responsible for similar levels of mercury in lakes, bays, and streams in other areas throughout the U.S. A Canadian study found similar levels of mercury contribution from dental offices into lakes and streams, and surveys of dental office disposal practices found the majority violated disposal regulations, and dangerous levels of mercury are accumulating in pipes and septic tanks from many offices(19,41,26).
The total discharge into sewers from dental amalgam at individual homes and businesses is almost as large as that from dental offices, since the average person with amalgam fillings excretes in body waste approx. 100 micrograms per day of mercury (86,87,89,520). This has also been confirmed by medical labs (13c), such as Doctors Data Lab in Chicago and Biospectron in Sweden, which do thousands of stool tests per year and is consistent with studies measuring levels in residental sewers by municipalities (13b). In the U.S. this would amount to approximately 7300 kilograms per year into sewers or over 8 tons per year. Thus the amount of mercury being excreted from dental amalgam is more than enough to cause dangerous levels of mercury in fish in most U.S. streams into which sewers empty. Studies by Oak Ridge National Laboratory (U.S. Dept. of Energy) and other studies have confirmed high levels of mercury in sewers and sewer sludge (42,43). According to an EPA study the majority of U.S. sewerage plants cannot meet the new EPA guideline for mercury discharge into waterways that was designed to prevent bioaccumulation in fish and wildlife due to household sewer mercury levels (15,13). Over 3 tons of mercury flows into the Chesapeake Bay annually from sewer plants, with numerous resulting fish consumption advisories for that area and similar for other areas (17). The EPA discharge rule had been reduced due to a National Academy of Sciences report of July 2000 that found that even small levels of mercury in fish result in unacceptable risks of birth defects and developmental effects in infants (18)."
Shall I go on ? Mercury is highly toxic. It's in our mouths, and there are many diference types of pathways for amalgam-bound mercury to be released into the human body.
This is not really a profound tale.
posted by troutfishing at 9:00 PM on February 23, 2004
troutfishing,
Cutting and pasting from a biased website with serious credibility issues is a poor substitute for argument.
Have you taken a good, hard look at the website you are quoting from? It is devoid of credibility. It is biased and commercial in nature. They exploit fear based on unsubstantiated anecdotes, pseudoscience and misinformation to steer people towards their list of 'safe' dentists (who, I would imagine, are quacks that will offer to replace those 'dangerous' fillings with gold).
Please find a credible source and try again. Look for peer review, science, controls and credibility. Also, try to find websites that are not commercial in nature.
Also, while we are on the topic, here's the ADA's stance on amalgam and a consumer update.
posted by cup at 2:38 AM on February 24, 2004
Cutting and pasting from a biased website with serious credibility issues is a poor substitute for argument.
Have you taken a good, hard look at the website you are quoting from? It is devoid of credibility. It is biased and commercial in nature. They exploit fear based on unsubstantiated anecdotes, pseudoscience and misinformation to steer people towards their list of 'safe' dentists (who, I would imagine, are quacks that will offer to replace those 'dangerous' fillings with gold).
Please find a credible source and try again. Look for peer review, science, controls and credibility. Also, try to find websites that are not commercial in nature.
Also, while we are on the topic, here's the ADA's stance on amalgam and a consumer update.
posted by cup at 2:38 AM on February 24, 2004
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