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Case Series

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M Vahabzadeh, M Balali-Mood

Abstract

Medical Toxicology Re- Occupational exposure to elemental mercury vapor usually occurs through inhalation dur-
search Center, Faculty ing its utilizations. This leads to a variety of adverse health effects. In some Islamic cities,
of Medicine, Mashhad this type of poisoning may occur during gilding of shrines using elemental mercury with gold.
University of Medical Herein, we report on three male patients aged 20–53 years, who were diagnosed with oc-
Sciences, Mashhad, cupational metallic mercury poisoning due to gilding of a shrine. All patients presented with
Iran neuro-psychiatric disorders such as anxiety, loss of memory and concentration, and sleep
disorders with high urinary mercury concentrations of 326–760 µg/L upon referring, 3–10
days after cessation of elemental mercury exposure. Following chelating therapy, the patients
recovered clinically and their mercury concentrations declined to non-toxic level (<25 µg/L).
Health, environmental and labor authorities, as well as the gilders should be aware of the
toxicity risk of exposure to metalic mercury during gilding in closed environments and act ac-
cordingly.

Keywords: Mercury; Mercury compounds; Mercury poisoning; Occupational exposure;

Mercury poisoning, nervous system

Correspondence to Introduction exposure to mercury usually occurs by in-
Mahdi Balali-Mood, MD, halation during manufacturing (eg, using
PhD, Visiting Professor Mercury is naturally produced this element for fluorescent bulb factory).3
of Newcastle Univer- in small amounts in the form Amalgam, which is used in restorative
sity, UK, Professor of of elemental mercury. Metallic dentistry, contains 50% elemental mer-
Medicine and Clinical mercury is a silver-colored liquid known cury that may be absorbed and increase
Toxicology, Director, as quicksilver. It is an extremely toxic el- urinary mercury concentration.4 There
Medical Toxicology ement that possesses two different com- are also studies that illustrate positive re-
Research Center, Imam pounds including inorganic (eg, mer- lationship between occupational exposure
Reza Hospital, Mash- curous chloride, mercuric chloride, and to mercury vapors from amalgam and in-
had 91735-348, Iran mercuric oxide) and organic compounds creased risk of infertility and miscarriage
Tel: +98-511-881-9301 (eg, methyl mercury and dimethyl-mercu- in women.5,6
Fax: +98-511-800-2467 ry).1 Elemental or metallic mercury is the
E-mail: BalalimoodM@ only metal existing in liquid form. It evap- In the processing and preparation of the
mums.ac.ir orates at room temperature, and if inhaled liquid for gilding, huge amounts of metal-
Received: Feb 11, 2016 for a long time, may well induce toxicity.2 lic mercury are used to form a blend with
Accepted: Mar 6, 2016 gold. This mixture is then heated to vapor-
Absorption of elemental mercury oc- ize the mercury after applying. This results
curs through inhalation, aspiration, sub- in a substantial release of mercury leaving
cutaneous exposure, and rarely, direct the gold to cover the desired surface.7
intravenous embolization. Volatilization
of elemental mercury will drastically be There are reports of acute mercury poi-
enhanced when it is heated.1 Occupational soning following exposure to mercury va-
pors in smelting of placer gold and extrac-

Cite this article as: Vahabzadeh M, Balali-Mood M. Occupational metallic mercury poisoning in gilders. Int J
Occup Environ Med 2016;7:116-122.

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case series

M. Vahabzadeh, M. Balali-Mood

tion process in gold mining,8,9 however, eter (Perkin Elmer, Model 3030) using
to the best of our knowledge, no cases of the mercuric hydride system (MHS) in the
elemental mercury toxicity in gilders has Toxicology Laboratory of the Medical Tox-
so far been reported. Herein, we report on icology Research Center.
three cases of occupational metallic mer-
cury poisoning due to gilding. For all patients, additional laboratory
tests including urinalysis, serum sodium,
We obtained approval of the University potassium, calcium, creatinine, CBC, ESR,
Research Ethics Committee as well as the and CRP, were requested; all results were
informed consents from all the patients for within the normal range. Further inves-
their treatment and publishing their infor- tigations such as spirometry, chest x-ray,
mation. NCV, and EMG were also normal in all pa-
tients. The patients were treated as outpa-
Case Reports tients.

General Findings Case 1

The patients were all Iranian professional The patient, a 30-year-old male, worked as
gilders who had been employed to gild a a guilder eight hours a day for 50 consecu-
shrine dome in another country for a cou- tive days. He then developed weakness,
ple of months. In the process of gilding, all malaise, excessive diaphoresis, coughing,
guilders mixed liquid mercury with gold fever, shortness of breath, diarrhea, dys-
powder to create a blend of gold; they then phasia, and polyuria. He therefore stopped
daubed it on the surface of walls of interior working and returned to his home town,
surfaces of the shrine building. Then, the where he was visited a private physician
superficial layer was heated to extremely and then a medical toxicologist. Clinical
high temperatures to vaporize the mercury examination revealed anxiety, restless-
leaving the gold on the surface. Unfortu- ness, memory weakness, insomnia, and
nately, during this process, the workers depression. He had a blood pressure of
had no suitable gloves, goggles and masks. 105/70 mm Hg, pulse rate of 78/min, and
They only used latex gloves and textile respiratory rate of 18/min. His deep ten-
masks. The ventilation in the area was in- don reflexes were exaggerated; no other
adequate; the ventilation system was in- sign was found. The initial urinary mer-
stalled at top of the fourth floor of the four- cury concentration three days after ces-
story shrine—two floors above the place sation of elemental mercury exposure
where the workers were gilding. Moreover, was 760 µg/L. Dimercapto succinic acid
there was a canister of activated charcoal or succimer was administered orally 200
on the third floor, which was exchanged mg, tid, for two weeks, followed by 200
every 4–7 days. The three men worked 6–8 mg, bid, for another two weeks. After the
hours a day for approximately 20–50 days. first chelating therapy, his urinary mercu-
The patients suffered from neuropsychiat- ry concentration reduced to 348 µg/L. Af-
ric disorders after they returned home in ter two weeks, another course of succimer
Mashhad, where they were referred to a was administered and the urinary mercury
medical toxicologist for consultation. Fol- concentration declined to 130 µg/L. Garlic
lowing clinical examination, occupational tablet, 400 mg allicin, tid, was then pre-
metallic mercury poisoning was suspected. scribed for three months. The final urinary
Urinary mercury concentration was mea- mercury concentration almost six months
sured by an atomic absorption spectrom- of the treatment was 25 µg/L. The patient
was then symptom free. He was advised to

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Occupational Elemental Mercury Poisoning

avoid any chemical exposure particularly blowing industries has made the elemental
to mercury. mercury vapor, an important cause of oc-
cupational, accidental and even intention-
Case 2 al exposures.10,11 Clinical manifestations
and route of exposure in some patients
This 20-year-old man complained of a me- presented with metallic mercury poison-
tallic taste and mild anorexia during his ing are presented in Table 1.
gilding work. He experienced 8 kg weight
loss after 60 days of gilding (8 hours dai- Cultural and ritual use of metallic mer-
ly). No obvious neuropsychiatric, pulmo- cury may also lead to exposures to high
nary or gastrointestinal signs were found levels of mercury vapor.19 Mercury has also
on physical examination. His initial uri- been used in gold mining to achieve a sta-
nary mercury concentration measured one ble compound of gold and mercury, which
week after cessation of elemental mercury is then heated to melt the mixture and sep-
exposure, was 635 µg/L; the level reduced arate the gold. Workers in such jobs may
to 351 µg/L after the first course of the expose to significant amounts of mercury
treatment with succimer as described for if the workplace sanitation control is not
the first patient. We also prescribed garlic properly considered. Exposure to mercury
as was done for the first case, however un- vapor can occur through using paints con-
fortunately, the patient did not return on taining phenyl-mercuric compounds. Mer-
his appointments and just informed us in cury vapors also release while the paints
a telephone conversations that he was do- are drying.20
ing fine.
The only biologically significant route
Case 3 of absorption of elemental mercury is in-
halation. Being quickly partitioned to
This 53-year-old man had two periods of other tissues, the initial half-life of metal-
metallic mercury exposure, each of which lic mercury following a single exposure is
lasted for almost 50 days. He had persis- around three days. Because of this short
tent cough, dyspnea and insomnia. His half-life in the blood, there is trivial cor-
vital sign was normal except for a blood relation between blood and urinary mer-
pressure of 165/100 mm Hg. On his physi- cury concentrations. Normally, mercury
cal examination, deep tendon hyperre- is excreted by the kidneys. Nevertheless,
flexia was found the only abnormal find- in exceedingly high exposures, the major
ing. His urinary mercury concentration 10 route of elimination of mercury is exhala-
days after cessation of elemental mercury tion.20 Neurotoxic effects of metallic mer-
exposure was 326 µg/L; the level declined cury vapor are attributable to the divalent
to 20 µg/L after the treatment given as de- mercury ions formed through oxidation in
scribed for case 1. the brain, which are more toxic than mon-
ovalent elemental mercury compounds.
Discussion One possible mechanism is interference
with enzyme functions by binding to their
For centuries, mercury has been used in sulfhydryl groups. Transport through the
industry. Being a frequent component in cell membrane via the formation of carrier
numerous medications, mercury has also complexes can be considered as another
been used widely in medicine. Widespread possibility.21
use of metallic mercury in manufactur-
ing fluorescent light bulbs, thermometers, Studies have revealed that humans ex-
barometers, dental amalgam, and glass- posed occupationally to metallic mercury
or amalgams had a significantly more in-

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M. Vahabzadeh, M. Balali-Mood

cidence of lymphocytic aneuploidy but not hazards, mercury is listed as a hazardous
structural chromosomal aberrations com- air pollutant generally known or assumed
pared to a control group. Chronic absorp- to cause serious health risks. According
tion due to handling of mercury or expo- to the World Health Organization,23 the
sure to its vapors has led to a characteristic 8-hour time-weighted average (TWA) for
discoloration of the anterior surface of the elemental and inorganic mercury is 25 µg/
lens.22 In another study on 75 workers ex- m3. According to the National Institute for
posed to mercury vapor in a glass manu- Occupational Safety and Health (NIOSH),
facturing factory, six experienced insom- the Recommended Exposure Limit (REL)
nia and one had tremors. One-third of the for mercury is 50 µg/mL, as a TWA expo-
workers had hyper-excitability and 20% sure for up to 10 hours a day, 40 hours a
had tremors. Based on such exposures and week.24

Table 1: Clinical manifestations and route of exposure in some patients with metallic mercury poisoning reported

from different countries.

Age Route of expo- Clinical manifesta- Elemental mer- Country Refer-
(yrs)/ sure tions cury concentra- Treatment ence
sex tion (μg/L)

Ingestion, inha- Severe pneumonitis, Blood: 1577 Hemodialysis, No Japan 12
67/Male lation (suicidal ARF*, anuria chelating therapy

attempt)

46/Fe- Manometer used Severe pain, ischemia, Nitroglycerin patches, 13
male in the arterial line erythematous lesions, Blood: 192.9 codeine, acetamino- Brazil
cyanosis of the left hand phen, and penicillamine

40/Male Self-injection of Schizophrenia and 24-h urine: 6 Broad-spectrum antibi- 14
elemental mercury inflammatory soft tissue otics, surgical debride- USA
lesions ment of necrotic tissue

Self-injection of

21/Male elemental mercury Granuloma in the Serum: 11 Surgical removal of Georgia 15
by breaking antecubital fossa mercury

thermometers

Repeated self- Arthromyalgias, fever,
weakness, chest pain
22/Male administration of (multiple punctuates Blood: 370 Mercury micro-emboli Spain 16
metallic mercury metallic densities in management
radiographs)
injection

Chronic mercury Rash, sore throat, fever,
chills, cough and diar- N/A
36/Male vapor exposure rhea Chelating therapy with USA 17
and possible iv DMSA† and DMPS‡

injection

36/Fe- Heating the liquid Abdominal pain, Not tested on ad- Symptomatic chelation 18
male form of mercury diarrhea and fever mission—blood: treatment with N-acetyl Turkey
300 at discharge cysteine (NAC)

*ARF: Acute renal failure; †DMSA: Dimercaptosuccinic acid; ‡DMPS: Dimercapto-propane-sulfonic acid; N/A: Not available

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Occupational Elemental Mercury Poisoning

For more information Measurement of blood mercury level tion, weakness, headaches, and visual
on occupational expo- is important in acute mercury poisoning, disturbances. However, the lethal dose of
sure to mercury among if the samples are taken within a few days inhaled elemental mercury has not been
workers in a fluores- of exposures. However, a 24-hour urine described.20
cent lamp factory see sample is more indicative of the expo-
http://www.theijoem. sure.25 Based on our experience, collection In addition to the previously mentioned
com/ijoem/index.php/ of 24-hour urine is not reliable in Iranian symptoms, numerous neurological, re-
ijoem/issue/view/21 outpatients; we thus decided to use morn- productive, pulmonary, renal, muscular,
ing urine samples. The normal range of and dermal symptoms have also been re-
mercury concentration in whole blood and ported following exposure to metallic mer-
urine is generally considered <10 µg/L cury;27-30 none of these symptoms was ob-
and <25µg/L, respectively.20 Nonetheless, served in our patients.
since organs other than blood can con-
centrate the mercury at higher levels in Diagnosis of chronic mercury poisoning
chronic mercury poisoning, there are re- is usually based on a history of occupation-
ports that indicated no precise correlation al exposure, clinical manifestations, and
between urinary mercury concentration high concentrations of urinary elemental
and clinical manifestations.26 mercury. However, the initial diagnosis
can be complicated, as many of the clini-
Although our patients were poisoned cal findings resemble those of neurological
with metal mercury vapor via inhalation, diseases, vitamin or mineral deficiencies,
they had no clinically significant signs; and psychological disorders.1,29
they presented with only mild clinical
manifestations, mostly different symp- Generally, the initial step in the man-
toms (Table 1). In contrast, their urinary agement of occupational poisonings is to
mercury concentrations were much higher withdraw the patient from the site of the
than the upper normal limit. This might be exposure, which may be sufficient in mild
due to the fact that when exposure to mer- symptomatic patients. However, in those
cury vapor is stopped, the blood mercury with high urine or blood mercury concen-
reduces quickly. Therefore, blood testing is trations and in patients with significant
only useful for continuous or very recent clinical manifestations, chelating thera-
exposures. For the metallic mercury in the py must be considered.29 We used “meso
body eliminates mainly via the urinary sys- 2,3-dimercaptosuccinic acid or DMSA,”
tem, urine samples are the best indicators commonly known as succimer, which has
to assess the chronic exposure to metallic been approved by the US Food and Drug
mercury. Although, urinary mercury con- Administration (FDA).31 DMSA can elimi-
centrations above 25 µg/L indicates expo- nate mercury stronger than N-acetyl-D,
sure to mercury, clinical symptoms and and L-penicillamine, by decreasing mer-
signs of toxicity will not necessarily appear cury levels in tissues and improving its ex-
for some times after chronic exposure.25 cretion.32

The initial symptoms of acute elemen- We also prescribed garlic tablets since it
tal mercury inhalation may occur within has been shown that garlic can reduce ac-
hours of exposure in some patients. The cumulation of some heavy metals and ef-
symptoms include cough, chills, fever, fectively reduce clinical manifestations in
and shortness of breath. Gastrointestinal occupational poisoning.33 Moreover, garlic
complaints such as nausea, vomiting, and can effectively protect rats' liver against
diarrhea might also happen, accompany- accumulation of cadmium and mercury
ing by a metallic taste, dysphagia, saliva- while administering before, with or after
exposure to such heavy metals. Possible
mechanisms of action are perceived as

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M. Vahabzadeh, M. Balali-Mood

involving in chelating and preventing the cupational exposure in dentistry and miscarriage.
absorption, uptake, accumulation, and ex- Occup Environ Med 2007;64:127-33.
cretion of heavy metals.34
6. Rowland AS, Baird DD, Weinberg CR, et al. The
Protection guidelines for workers should effect of occupational exposure to mercury vapour
be the first step in preventing mercury va- on the fertility of female dental assistants. Occup
por poisoning. In areas with excessive ex- Environ Med 1994;51:28-34.
posures to mercury, respiratory protection
must be applied by full-face canister type 7. Klaassen CD. Casarett & Doull's Toxicology; The Ba-
mask or supplied air respirator, depending sic Science of Poisons. 7th ed. McGraw-Hill, 2008:
on the concentration of mercury vapors. 947-50.
Concentrations above 50 mg elemental
mercury/m3 of elemental mercury in work 8. Donoghue A. Mercury toxicity due to the smelt-
environment requires supplied air and use ing of placer gold recovered by mercury amalgam.
of positive-pressure full-face respirators. Occup Med 1998;48:413-5.
Full bodywork clothes including shoes or
shoe covers, goggles, suitable gloves and 9. Lilis R, Miller A, Lerman Y. Acute mercury poison-
hats must also be applied.35 ing with severe chronic pulmonary manifestations.
CHEST Journal 1985;88:306-9.
In conclusion, occupational poison-
ing due to exposure metallic mercury may 10. Mercury toxicity. Agency for Toxic Substance and
occur during gilding process. Training Disease Registry. Am Fam Physician 1992;46:1731-
the gilders in potential health hazards of 41.
mercury exposure and utilizing suitable
protection is imperative. Moreover, the 11. Clarkson TW, Magos L, Myers GJ. The toxicology of
health, environmental and labor authori- mercury--current exposures and clinical manifesta-
ties should be aware of the risk of toxicity tions. N Engl J Med 2003;349:1731-7.
of metal mercury exposure during gilding,
particularly in closed environments, and 12. Katsuma A, Hinoshita F, Masumoto S, et al. Acute
act accordingly. renal failure following exposure to metallic mer-
cury. Clin Nephrol 2014;82:73-6.
Conflicts of Interest: None declared.
13. de Souza AC, de Carvalho AM. Metallic Mercury
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