Author: Alberto Gambino
Date: 05/10/2007


Alberto Gambino & Andrea Quirico


The metal exists in three fundamental forms two of which inorganic (Hg++ and Hg3+) and the third one organic methyled form(CH3Hg).
The principal engagement street by the humans is through alimentary cycle. There are saprophyte bacteria of the intestinal flora with turning capacity the inorganic Hg salts into organic compounds, so that the inhaleted mercury as steam can be absorbed through the intestinal mucosa.
The human emivita of the organic mercury is 70 days and the inorganic one is 40 days.
Mercury is also absorbed through skin and lungs, then it is given by the blood to all organs and the main way of excretion is urine. The mercury penetrates into cellular membranes by with its liposolubility and it interferes with the cellular metabolism, in particular Hg++ has big affinity with the sulphur of the sulphidrilic group SH giving rise to S-Hg which inhibits a few enzymic systems, blocking 2 important metabolic phases of the Krebs cycle , attaching Acetil-coA and the synthesis of the P450 cythocrome .


Also known as “mad hatter syndrome”, there are two types of poisoning:
- acute: very rare due to casual events (ingestion, epithelial lesions)
- chronic: micromercurialism with the following precocious symptoms: gingivitises and stomatitises, caused by Hg deposited in the salivary glands and poured in mouth with the saliva.
The potential mutagenicity of the mercury derives from his chemical tie capacity with RNA and then in the possible alteration of the mechanisms of replication of the genetic material; also low amounts show an increase in the frequency of the gpt gene mutation which takes to the appearance of mytotic figures and resulting aneuploidia and poliploidia of the emergent cells.


About the 1% of the organic mercury is directly expelled with the urine, but can be acetylated in the liver or combined with cysteine or glutathione. The n-acetil-omocystein-metilic mercury complex enters the circulation and is removed through the kidneys. The plasmatic mercury is expelled in minimum amount with the urine through the mechanism of the glomerulare filtering. To evaluate with an acceptable approximation the exposure level we can base on the analysis of the excretion profile of the porphyrines.
The nefrotoxicity of the mercury has been also evaluated through the measurement of a few cellular enzymes typical of the tubular epithelium as the b-glutamyltranspherase and b-galactosidase, b-glucuronidase and the n-acetil-b-glucosaminydase (NAG).


In nervous cell the immediate damage of the mercury is correlated to its perturbing action the electric function. The ion mercury is able to force the passage through the sodium and calcium channels causing depolarization and a accentuated release of neurotransmitters. After such action an irreversible block of the neurotransmitters emission follows and then a functional paralysis of the neuron itself. The existence of enzymatic inhibitions has been confirmed in particular of the ADP ribossilation which constitutes a fundamental process of the neuronal proteins metabolism. The enzyme inhibition of prevents formation of ribosilated actin and tubuline (structural proteins of the cytoskeleton) with consequent production of inactive intermediates. The final effect is the formation of neurofibril tangles like the ones discovered in the Alzheimer disease. Elimination from the SNC is slow due to his oxidation to ionic bivalent mercury that cannot anymore exceed the ematoencephalic barrier and this supports the store.


The mercury chloride and the metal mercury induce auto-immune phenomena. The pathogenic mechanism with which the pathology is set up consists in a policlonal b-lymphocytes activation through T cells with production of direct antibodies against the self which arrange themselves in a linear way along the basal membrane.
It causes the appearance of a membranous glomerulonefrite with subepithelial deposits of IgG which tends to evolve towards the nephrosic syndrome, preceded by increase of circulating IgE .
The appearance of autoimmune reactions has been proved also in the lung with similar demonstrations to the Goodpasture syndrome.
Various jobs suggest that the mercury not cause such damages:
lymphocyte levels in subjects with and without amalgam restorations
failure to detect effect of amalgam restoration on peripheral blood lymphocyte population


Only the 5% of the patients is clearly allergic to the mercury present in the amalgam. We have to remember that other researches have highlighted cutaneous ipersensibility reactions to the mercury given out patch test in 2 -35% of the subject bearers of obturations. The allergy symptoms are:
- dermatitises
- urticaria eczema, eritematose reactions with interest of face, neck, arms and thorax, oral lichenoidi reactions.


The mercury has been discovered in the maternal milk and many scientific publications document the passage through the placentar barrier.
Not all the chemical forms of the mercury have the same capacity to cross the placentar barrier, the two forms in absolute most subject to diffusion are the metal mercury and the metylmercury due to their liposolubility.
Some researches show the existence of alterations in the development of the nervous system of the fetus already to low mercury concentrations in the tissues.
In a recent study the concentration of the mercury has been evaluated in the amniotic liquid comparing it with the number and the occlusal extention of the obturations and a statistically significant relation exists between occlusal extention of the restorations and concentration of the metal. The ADA has performed a research on the results of the pregnancies by sending questionnaires to dentists and dental assistants concerning the mercury use; however the results have not pointed out any correlation between the levels of abortions or the incidence of congenital anomalies in the progenie.


The maximum levels of exposure for the airy polluting are said TLV (threshold limit value), among these the Hg steams are included . A mercury concentration in the air lower than 1 mg/m3 is shown as maximum dose.

valuesHg vapour of inorganic and organic not alcalin Hgetyl and metyl Hg

TLV-TWA = Hg vapour concentration which a subject can tollerate 8h/die in a week
TLV-C = maxim airy Hg concentration during working time
TVL-STEL = maxim airy Hg concentration acceptable for at last 15 minuts in a working day
IDHL = danger of life

2012-05-23T13:49:49 - Paola Brizio


The U.S.A. Environmental Protection Agency devotes part of its site to the problem of mercury: from the exposure to the Health Effects.
Also the U.S.A. Geological Survey (USGS) treats the environmental pollution and factors that can contribute to this.


The U.S.A. Food and Drug Administration (FDA) underlines the risk of exposure to the most dangerous form of mercury, methylmercury, from the diet, highlighting Mercury Levels in Commercial Fish and Shellfish in the last twenty years.

Searching on the European Rapid Alert System for Food and Feed (RASFF) portal, the exceeding of maximum limits of heavy metals in fishes and fish products, in the last year, 85% of them concerns mercury.


In the COMMISSION REGULATION (EC) No 1881/2006 of 19 December 2006 and in the COMMISSION REGULATION (EU) No 420/2011 of 29 April 2011, amending Regulation (EC) No 1881/2006, are set maximum levels for certain contaminants (Mercury included) in foodstuffs. Summarizing:

{background:#ddd}. |_. Maximum levels | _. mg/kg wet weight |
|=. Fishery products and muscle meat of fish, excluding species listed below | =. 0,50 |
|=. Muscle meat of the following fish: anglerfish (Lophius species), atlantic catfish (Anarhichas lupus), bonito (Sarda sarda), eel (Anguilla species), emperor, orange roughy, rosy soldierfish (Hoplostethus species), grenadier (Coryphaenoides rupestris), halibut (Hippoglossus hippoglossus), marlin (Makaira species), megrim (Lepidorhombus species), mullet (Mullus species), pike (Esox lucius), plain bonito (Orcynopsis unicolor), poor cod (Tricopterus minutes), portuguese dogfish (Centroscymnus coelolepis), rays (Raja species), redfish (Sebastes marinus, S. mentella, S. viviparus), sail fish (Istiophorus platypterus), scabbard fish (Lepidopus caudatus, Aphanopus carbo), seabream, pandora (Pagellus species), shark (all species), snake mackerel or butterfish (Lepidocybium flavobrunneum, Ruvettus pretiosus, Gempylus serpens), sturgeon (Acipenser species), swordfish (Xiphias gladius), tuna (Thunnus species, Euthynnus species, Katsuwonus pelamis) |=. 1,00 |


Mercury speciation in the muscle of two commercially important fish, hake (Merluccius merluccius) and striped mullet (Mullus barbatus) from the Mediterranean sea: estimated weekly intake

M.M Storellia, A Storellia, R Giacominelli-Stufflerb, G.O Marcotrigiano

Total mercury and methylmercury concentrations were measured in the muscle tissue of two fish species from the Ionian and Adriatic seas. Higher total mercury and methylmercury concentrations were detected in striped mullet (Mullus barbatus), a benthic species (Ionian sea: Hg=0.40 μg g−1 wet wt, MeHg=0.40 μg g−1 wet wt; Adriatic sea: Hg=0.49 μg g−1 wet wt, MeHg=0.44 μg g−1 wet wt), than in hake (Merluccius merluccius), a pelagic species (Ionian sea: Hg=0.09 μg g−1 wet wt, MeHg=0.09 μg g−1 wet wt; Adriatic sea: Hg=0.18 μg g−1 wet wt; MeHg=0.16 μg g−1 wet wt). Total mercury residues were determined in all samples of both species from the Adriatic sea, while levels below the limit of detection were registered in 25% and 11%, respectively, of striped mullet and hake samples from the Ionian sea. In 18.8% and 22.2% of striped mullet samples from the Ionian and Adriatic seas, respectively, total mercury concentrations exceeded the maximum level fixed by the European Commission Decision (Hg=0.5 μg g−1 wet wt). In the two different species, mercury was present almost completely in the methylated form with mean percentages between 60% and 100%. The estimated weekly intake for total mercury was below the established the provisional tolerable weekly intake (PTWI) for both species, though their consumption provides a methylmercury intake above the WHO safety limit.

Food Chemistry, Volume 89, Issue 2, February 2005, Pages 295–300

Hair mercury levels in an urban population from southern Italy: Fish consumption as a determinant of exposure

Sergi Díeza, Paolo Montuoric, Adele Paganoc, Pasquale Sarnacchiaroc, Josep M. Bayonab, Maria Triassic.

Mercury levels in hair of a general population, 237 adults aged between 35–45, in Naples, Italy, were assessed. The subjects were asked to fill in a questionnaire about age, gender, body weight, height, body mass index (BMI), fish consumption, number, surface and area of dental amalgam fillings. Total mercury (THg) concentrations in human hair ranged from 0.221 to 3.402 μg/g and the mean value for the subjects under study was 0.638 μg/g. Study participants were divided into three groups in accordance with fish consumption and dental amalgam: ANF (amalgam and no fish); NAF (no amalgam but with fish) and AAF (amalgam and fish). Significant differences in THg were found in the three groups (p < 0.05). A multiple linear regression analysis showed a weak but significant correlation of THg content in hair with respect to gender and age, but almost no association was found between THg and dental fillings. Conversely, a strong correlation was obtained between THg and fish consumption regardless of the group evaluated. Finally, mercury levels in hair exceeded the levels corresponding to the EPA reference dose (RfD) of 0.1 μg Hg/kg body weight per day (1 μg Hg/g hair) in 6% of the population (4% men and 2% women). However, the THg limits in our subjects were not exceeded according to the WHO guidelines, which use a benchmark dose of 0.23 μg Hg/kg bw/day (14 μg Hg/g maternal hair).

Environment International, Volume 34, Issue 2, February 2008, Pages 162–167

Concentration, distribution, and translocation of mercury and methylmercury in mine-waste, sediment, soil, water, and fish collected near the Abbadia San Salvatore mercury mine, Monte Amiata district, Italy

Valentina Rimondia, John E. Grayb, Pilario Costagliola, Orlando Vasellia, Pierfranco Lattanzi

The distribution and translocation of mercury (Hg) was studied in the Paglia River ecosystem, located downstream from the inactive Abbadia San Salvatore mine (ASSM). The ASSM is part of the Monte Amiata Hg district, Southern Tuscany, Italy, which was one of the world’s largest Hg districts. Concentrations of Hg and methyl-Hg were determined in mine-waste calcine (retorted ore), sediment, water, soil, and freshwater fish collected from the ASSM and the downstream Paglia River. Concentrations of Hg in calcine samples ranged from 25 to 1500 μg/g, all of which exceeded the industrial soil contamination level for Hg of 5 μg/g used in Italy. Stream and lake sediment samples collected downstream from the ASSM ranged in Hg concentration from 0.26 to 15 μg/g, of which more than 50% exceeded the probable effect concentration for Hg of 1.06 μg/g, the concentration above which harmful effects are likely to be observed in sediment-dwelling organisms. Stream and lake sediment methyl-Hg concentrations showed a significant correlation with TOC indicating considerable methylation and potential bioavailability of Hg. Stream water contained Hg as high as 1400 ng/L, but only one water sample exceeded the 1000 ng/L drinking water Hg standard used in Italy. Concentrations of Hg were elevated in freshwater fish muscle samples and ranged from 0.16 to 1.2 μg/g (wet weight), averaged 0.84 μg/g, and 96% of these exceeded the 0.3 μg/g (methyl-Hg, wet weight) USEPA fish muscle standard recommended to protect human health. Analysis of fish muscle for methyl-Hg confirmed that > 90% of the Hg in these fish is methyl-Hg. Such highly elevated Hg concentrations in fish indicated active methylation, significant bioavailability, and uptake of Hg by fish in the Paglia River ecosystem. Methyl-Hg is highly toxic and the high Hg concentrations in these fish represent a potential pathway of Hg to the human food chain.

Science of The Total Environment, Volume 414, 1 January 2012, Pages 318–327

Levels of mercury and polychlorobiphenyls in commercial food in Siena Province (Tuscany, Italy) in the period 2001–2010

Silvano Focardi

In this paper, the presence and amount of mercury and polychlorobiphenyls (PCBs) were determined in more than 1000 food items collected monthly in the period 2001–2010 in commercial food shops in Siena (Tuscany, Italy), in order to assess risk to humans due to food consumption. The overall results clearly show a strong difference in concentration of the two contaminants between foods from the terrestrial trophic web and those from the marine trophic web. Particular attention was paid to study the Mediterranean swordfish (Xiphias gladius) and bluefin tuna (Thunnus thynnus) because anthropic impact on these species is great due to their topmost position in trophic webs; thus it is very important to know their health status and evaluate their toxicity for humans. Many samples of bluefin tuna and swordfish show mercury levels higher than 0.5 mg/kg f.w., which is the maximum level set by the European Commission (EC, Regulation n. 1881/2006) for most fish species. Taking into account the important nutritional contribution that fish makes to the diet, it is advisable that women of childbearing age, pregnant and breastfeeding women as well as young children select fish from a wide range of species, without giving undue preference to large predatory fish such as swordfish and tuna. In any case, it is interesting to note a significant decrease in levels of both mercury and PCBs in bluefin tuna and swordfish found in the Sienese market over the course of the past ten years.

Microchemical Journal, Available online 28 January 2012, In Press

Mercury in the sediments of the Marano and Grado Lagoon (northern Adriatic Sea): Sources, distribution and speciation

Alessandro Acquavitaa, Stefano Covellib, Andrea Emilib, Daniela Bertoc, Jadran Faganelid, Michele Gianie, Milena Horvatf, Neža Korond, Federico Rampazzoc

The existence of mining tailings in Idrija (Slovenia) and their subsequent transportation via the Isonzo River has been the primary source of mercury (Hg) in the northern Adriatic Sea for almost 500 years, making the Gulf of Trieste and the adjacent Marano and Grado Lagoon two of the most contaminated marine areas in the world. A further, more recent, contribution of Hg has been added by the operation of a chlor-alkali plant (CAP) located in the drainage basin flowing into the Lagoon. On the basis of previous research, as well as new data obtained from the “MIRACLE” project (Mercury Interdisciplinary Research for Appropriate Clam farming in a Lagoon Environment), the spatial distribution of Hg and its relationships with methylmercury (MeHg), organic matter and several geochemical parameters in surface sediments were investigated. The predominant and long-term impacts of the cinnabar-rich Isonzo River particulate matter in the Lagoon surface sediments are evident and confirmed by a decreasing concentration gradient from east (>11 μg g−1) to west (0.7 μg g−1). Hg originated from the CAP is only significant in the central sector of the Lagoon. Hg is primarily associated with fine-grained sediments (<16 μm), as a consequence of transport and dispersion from the fluvial source through littoral and tidal currents. However, speciation analyses highlighted the presence of Hg sulphides in the coarse sandy fraction of sediments from the eastern area, as expected given the origin of the sedimentary material. Unlike Hg, the distribution of MeHg (0.47–7.85 ng g−1) does not show a clear trend. MeHg constitutes, on average, 0.08% of total Hg and percentages are comparable to those obtained in similar lagoon environments. Higher MeHg concentrations in low to intermediate Hg-contaminated sediments indicate that the metal availability is not a limiting factor for MeHg occurrence, thus suggesting a major role played by environmental conditions and/or speciation. The reasonably good correlation between MeHg normalized to humic acid (HA) content and humic δ13C indicates that MeHg is preferentially associated with autochthonous δ13C-enriched HAs in lagoon surface sediments, suggesting that the structure of “marine” HAs, less refractory and less aromatic, could favor MeHg binding and/or production. In the context of the potential hazard of Hg and MeHg accumulation in reared clams, the choice of a site for the extension of farming activities inside the Marano and Grado Lagoon is dependent on several factors and cannot be decided solely on the basis of the total Hg content in the sediment.

Estuarine, Coastal and Shelf Science, Available online 24 February 2012, In Press.

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