Psychological and somatic subjective symptoms as a result of dermatological patch testing with metallic mercury and phenyl mercuric acetate

Is dental amalgam safe for humans? The opinion of the scientific committee of the European Commission

It was claimed by the Scientific Committee on Emerging and Newly Identified Health Risks (SCENIHR)) in a report to the EU-Commission that "....no risks of adverse systemic effects exist and the current use of dental amalgam does not pose a risk of systemic disease..." [1, available from: http://ec.europa.eu/health/ph_risk/committees/04_scenihr/docs/scenihr_o_016.pdf].SCENIHR disregarded the toxicology of mercury and did not include most important scientific studies in their review. But the real scientific data show that:(a) Dental amalgam is by far the main source of human total mercury body burden. This is proven by autopsy studies which found 2-12 times more mercury in body tissues of individuals with dental amalgam. Autopsy studies are the most valuable and most important studies for examining the amalgam-caused mercury body burden.(b) These autopsy studies have shown consistently that many individuals with amalgam have toxic levels of mercury in their brains or kidneys.(c) There is no correlation between mercury levels in blood or urine, and the levels in body tissues or the severity of clinical symptoms. SCENIHR only relied on levels in urine or blood.(d) The half-life of mercury in the brain can last from several years to decades, thus mercury accumulates over time of amalgam exposure in body tissues to toxic levels. However, SCENIHR state that the half-life of mercury in the body is only "20-90 days".(e) Mercury vapor is about ten times more toxic than lead on human neurons and with synergistic toxicity to other metals.(f) Most studies cited by SCENIHR which conclude that amalgam fillings are safe have severe methodical flaws.

Comments on the Article “The Toxicology of Mercury and Its Chemical Compounds” by Clarkson and Magos (2006)

Clarkson and Magos (2006) provide their perspectives on the toxicology of mercury vapor and dental amalgam. As scientists who are involved in preparing a German federal guideline regarding dental amalgam, we welcome additional scientific data on this issue. However, Clarkson and Magos do not present all the relevant studies in their review. The additional data provided here show that: (a) Dental amalgam is the main source of human total mercury body burden, because individuals with amalgam have 2-12 times more mercury in their body tissues compared to individuals without amalgam; (b) there is not necessarily a correlation between mercury levels in blood, urine, or hair and in body tissues, and none of the parameters correlate with severity of symptoms; (c) the half-life of mercury deposits in brain and bone tissues could last from several years to decades, and thus mercury accumulates over time of exposure; (d) mercury, in particular mercury vapor, is known to be the most toxic nonradioactive element, and is toxic even in very low doses, and (e) some studies which conclude that amalgam fillings are safe for human beings have important methodogical flaws. Therefore, they have no value for assessing the safety of amalgam.

The Potential Adverse Health Effects of Dental Amalgam

There is significant public concern about the potential health effects of exposure to mercury vapour (Hg(0)) released from dental amalgam restorations. The purpose of this article is to provide information about the toxicokinetics of Hg(0), evaluate the findings from the recent scientific and medical literature, and identify research gaps that when filled may definitively support or refute the hypothesis that dental amalgam causes adverse health effects. Dental amalgam is a widely used restorative dental material that was introduced over 150 years ago. Most standard dental amalgam formulations contain approximately 50% elemental mercury. Experimental evidence consistently demonstrates that Hg(0) is released from dental amalgam restorations and is absorbed by the human body. Numerous studies report positive correlations between the number of dental amalgam restorations or surfaces and urine mercury concentrations in non-occupationally exposed individuals. Although of public concern, it is currently unclear what adverse health effects are caused by the levels of Hg(0) released from this restoration material. Historically, studies of occupationally exposed individuals have provided consistent information about the relationship between exposure to Hg(0) and adverse effects reflecting both nervous system and renal dysfunction. Workers are usually exposed to substantially higher Hg(0) levels than individuals with dental amalgam restorations and are typically exposed 8 hours per day for 20-30 years, whereas persons with dental amalgam restorations are exposed 24 hours per day over some portion of a lifetime. This review has uncovered no convincing evidence pointing to any adverse health effects that are attributable to dental amalgam restorations besides hypersensitivity in some individuals.

Mercury intolerance and lymphocyte transformation test with nickel sulfate, palladium chloride, mercuric chloride, and gold sodium thiosulfate

The peripheral lymphocytes of 10 patients referred to as mercury intolerant and 9 patients referred to as tolerant with regard to presence or absence of psychosomatic symptoms when percutaneously exposed to low patch test doses of mercury were stimulated in vitro with four metal salts. In addition, cells from 7 subjects with no anamnestic mercury intolerance or allergy to metals as well as free from dental alloys were included as controls. Lymphocyte transformation test was done by in vitro challenge with five concentrations of gold sodium thiosulfate, nickel chloride, palladium chloride, and seven concentrations of mercuric chloride. Stimulation with palladium chloride and mercuric chloride showed a difference between the mercury-intolerant and -tolerant patients on one hand and the controls on the other, but there was no difference between the two patient groups. With regard to nickel sulfate, there was a significant dose-dependent stimulation in all the three groups but no difference between the groups could be seen. Gold sodium thiosulfate did not stimulate the lymphocytes at all. Based on these results, we therefore conclude that lymphocyte transformation test performed with the four metal salts cannot be used to further differentiate between mercury-intolerant and -tolerant patients.

(Un)usual effects of patch testing?

BACKGROUND

Little information is available concerning subjective complaints associated with patch testing.

OBJECTIVES

To gather information about the frequency and the nature of such complaints, and to evaluate, if possible, whether the complaints were really caused by patch testing.

PATIENTS/METHODS

Four hundred and thirty-three patients took part in a questionnaire study between December 1996 and October 1997. Complaints of itch and other subjective complaints, such as tiredness and feeling unwell, were recorded.

RESULTS

From the total group of 433 patients, 379 patients (87%) recorded one or more complaints on day 0. By day 2 this number was 383 patients (88%), with a significant reduction to 326 patients (75%) by days 3-4. Most complaints concerned itch on the back, and to a lesser extent tiredness. Fifty-four patients (54 of 433; 12%) did not report itch or other subjective complaints on day 0; of this group, 36 patients (66%) developed complaints by day 2. By days 3-4, 24 patients (44%) reported complaints: 20 patients from the day 2 group (37%) and four patients (7%) from days 3-4. Again the largest increase in complaints was found for itch on the back, but other complaints were also found to have increased, mainly tiredness, feeling unwell, headache, shakiness and light-headedness.

CONCLUSIONS

We conclude that patch testing can, in addition to local skin reaction and itch, also cause other subjective complaints in a number of patients.

Mercury intolerance in relation to superoxide dismutase, glutathione peroxidase, catalase, and the nitroblue tetrazolium responses

Through percutaneous provocation with metallic mercury and phenyl mercuric acetate in patients stating the presence of subjective psychosomatic symptoms following dental amalgam treatment, it has been possible to categorize and score two extreme groups of patients, mercury-intolerant and mercury-tolerant patients reacting and not reacting, respectively, to low doses of mercury. The intolerant patients had a high psychosomatic score and the tolerant patients had a low or null score when exposed to low doses of the two mercury compounds. Determination of the scavenger enzymes superoxide dismutase, glutathione peroxidase, and catalase showed no significant differences between the mercury-intolerant and the mercury-tolerant patients and the controls. The activity of superoxide dismutase and the quantitative psychosomatic score elicited by either metallic mercury or phenyl mercuric acetate showed a positive correlation. On the other hand, analyses of the psychosomatic score and the areas under the curves of the nitroblue tetrazolium test response showed negative correlations. The results indicate that the oxidative metabolism and, in particular, superoxide dismutase may be perturbed in mercury-intolerant patients.

Serotonin production in lymphocytes and mercury intolerance

Patients with suspected illness due to mercury in dental amalgam were classified as tolerant or intolerant depending on their psychosomatic responses following in vivo epicutaneous provocation with low doses (patch test doses) of metallic mercury and phenylmercuric acetate. Ten intolerant patients and nine tolerant patients plus seven healthy amalgam-free and metal non-allergic controls were recruited to the study. Peripheral blood lymphocytes were exposed in vitro to three concentration of mercuric chloride (0.92, 1.83 and 3.68 microM) with and without 10 microg phytohaemagglutinine (PHA)/ml and the release of serotonin into the supernatant was measured. Lymphocytes exposed only to HgCl(2) showed no significant dose-dependent increase of serotonin, but the response of the tolerant patients was significantly higher compared with the controls. No other differences were found. Co-culture with mercuric chloride and PHA showed a statistically significant dose-dependant release of serotonin, but no differences between the three clinical groups could be detected. Thus, our results could not validate the concept of mercury tolerance and intolerance.

In vitro lymphoproliferative assays with HgCl2 cannot identify patients with systemic symptoms attributed to dental amalgam

Dental amalgam is suspected, by some exposed individuals, to cause various systemic psychological, sensory, and neurological symptoms. Since not all amalgam-bearers experience such reactions, an individual characteristic--for example, a susceptible immune system--might explain these conditions. In vitro lymphocyte proliferation is a valuable tool in the diagnosis of allergy. With HgCl2 as the antigen, however, the test is hampered, because Hg2+ can cause unspecific lymphocyte proliferation, optimal at 1.4 to 9.5 micrograms HgCl2/mL. Recently, the use of suboptimal HgCl2 concentrations (< or = 0.5 microgram/mL) has been suggested to circumvent these problems. The main aim of this study was to investigate whether patients with systemic symptoms alleged to result from the presence of dental amalgam differ from healthy controls, with reference to in vitro lymphoproliferative responses to HgCl2 < or = 0.5 microgram/mL. Three different test protocols--lymphocyte transformation test (LTT) in micro- and macro-cultures, and the memory lymphocyte immunostimulation assay (MELISA)--were used. Other immune parameters--such as a standard patch test for dental materials, the number of T- and B-lymphocytes, monocytes, granulocytes, and NK cells in peripheral blood, allergic symptoms, and predisposition--were also investigated. Twenty-three amalgam patients, 30 healthy blood donors with amalgam, ten healthy subjects without amalgam, and nine patients with oral lichen planus (OLP) adjacent to dental amalgam and a positive patch test to Hg0 were tested. None of the investigated immune parameters revealed any significant differences between amalgam patients and controls. The sensitivity of in vitro lymphocyte proliferation ranged from 33 to 67%, with the OLP patients as a positive control group, and the specificity from 0 to 70% for healthy controls with a negative patch test to Hg0. Thus, despite the use of HgCl2 < or = 0.5 microgram/mL, a high frequency of positive results was obtained among healthy subjects with or without dental amalgam. Consequently, in vitro lymphocyte proliferation with HgCl2 cannot be used as an objective marker for mercury allergy in dental amalgam-bearers.

Chronic fatigue syndrome and nickel allergy

50 patients with chronic fatigue syndrome (CFS) and 73 controls were patch tested with 8 metal allergens. We found an overrepresentation of allergies among the CFS patients, which was not significant. However, allergy to nickel occurred in 36% of patients in the CFS group and in 19% of subjects in the control group (p<0.05). The high frequency of nickel allergy was more noteworthy in females in the CFS group than among female controls (52% and 24%, respectively, p<0.05). Similarly, in the males the figures were 14% and 9%. We suggest that in vivo immunoactivation by ions of nickel, or metal cross-reacting with nickel, could be an etiological factor in CFS.

Dental materials: 1996 literature review

This critical review of the published literature on dental materials for the year 1996 has been compiled by the Dental Materials Panel of the UK. It continues the series of annual reviews started in 1973 and published in the Journal of Dentistry. Emphasis has been placed upon publications which report upon the materials science or clinical performance of the materials. The review has been divided by accepted materials classifications (fissure sealants, glass polyalkenoate cements, dentine bonding, dental amalgam, endodontic materials, casting alloys, resin-bonded bridges and ceramo-metallic restorations, ceramics, denture base resins and soft lining materials, impression materials, implants materials, orthodontic materials, biomechanics and image processing, resin composites and casting investment materials and waxes). Three hundred and thirteen articles have been reviewed.