Mercury poisoning can occur from exposure to elemental, inorganic, and organic mercury. Elemental mercury exposure is usually from inhalation and causes respiratory and neurological symptoms. Inorganic mercury ingestion can cause gastrointestinal and kidney damage. Organic mercury exposure primarily from contaminated seafood causes delayed neurological effects like tremors and ataxia. Diagnosis is made through blood, urine, hair, and clinical exams. Chelation therapy with BAL or DMSA may be used for significant exposures. Public education is important to prevent mercury exposure and proper disposal.

1. Mercury(Hg) Poisoning
อ.นพ.วรพันธ์ เกรียงสุนทรกิจ
Ambulatory Pediatrics
Department of Pediatrics
คณะแพทยศาสตร์ศิริราชพยาบาล มหาวิทยาลัยมหิดล

2. Minamata disease
Kumamoto Prefecture, 1956

5. http://www.fda.gov/food/foodborneillnesscontaminants/metals/ucm115644.htm

6. Top 15 Fish – Mercury Levels
PPM / Oz.

8. 3 forms of mercury
 Organic:
Elemental / inorganic salts organic Hg
 Inorganic: Hg + other elements  compound or salts
used in industry, cosmetic skin creams
Elemental Hg inorganic Hg in the body
 Elemental: quick silver, thermometer, fluorescent light
bulb, electrical switch, dental amalgam
Microorganism in water/ soil

9. How people are exposed to Hg ?
 Elemental Hg: breath elemental Hg vapors (dental
office, smelting operation, Hg spilled or released )
 Inorganic Hg: Hg salts are used
 Organic Hg: seafood consumption (fish, shellfish
contaminated with methylmercury), pass through
the placenta , breast milk

10. Elemental (metallic) mercury (Hg0)

11. Inorganic mercury
 Mercurous ion
 Calomel, mercurous chloride
 Mercuric ion
 Mercuric chloride

12. Organic mercury
 Methylmercury
 Ethylmercury
 Dimethylmercury
 Methoxyethylmercury
 Phenylmercury

13. Pathophysiology
 Binding to sulfur
 Replacing hydrogen ion in sulfhydryl groups
 React with phosphoryl, carboxyl and amide group
 widespread enzymes dysfunction

14. Pathophysiology
 Mercury salt poisoning: necrosis of GI mucosa and
proximal renal tubules (shortly after exposure)
 Mercurial ointments use: membranous
glomerulonephritis, acrodynia
 Methyl mercury poisoning:
– fetal Minamata disease: atrophy of the cerebellar
hemispheres, postcentral gyri, calcarine area  ataxia,
sensory neuropathy, visual field constriction
– Less severe in adult

15. Clinical manifestations
 Elemental mercury
– Respiratory system: cough, chills, fever, shortness of
breath
 CXR: interstitial pneumonitis, atelectasis,
emphysema, interstitial fibrosis, restrictive lung
disease
– GI: N/V, dysphagia, weakness
– Headache, visual disturbance
– Sub-acute inorganic mercury poisoning: tremor, renal
dysfunction, gingivostomatitis

16. Elemental mercury
 Common in occupational setting
 Max. limit of ambient air concentration 0.9
mg/m3 (0.1 mg/m3)
 Children is more sensitive to mercury vapor:
minute ventilation to body size
 Direct aspiration of metallic mercury: massive
endotracheal hemorrhage
 Vacuuming spilled mercury

17. Dental amalgams
 Occupational exposure: acceptable low
 Vaporized mercury from chewing: clinically
insignificant
 Immunologic hypersensitivity: very rare cases

18. Amalgam (elemental Hg)
"Amalgam is not a true alloy. It is made up of 50% mercury, which is not locked
into a set filling but escapes continuously during the entire life of the filling in the
form of vapor, ions and abraded particles“
Australasian Society Of Medicine And Toxicology

19. Amalgam: advantages vs disadvantages
Patient
 Durable and cheap
 Low rate of local side effect
 No conclusive evidence for
systemic adverse effect
Environmental & health care
provider
 Decreased exposure due to
good conduct and Hg
hygiene protocols
 Environmental impact of
dental amalgam is almost
insignificant
J Ir Dent Assoc. 2013 Dec-2014 Jan;59(6):311-7.

20. Inorganic mercury
 Ingestion: caustic gastroenteritis, grayish
discoloration of mucous membrane, metallic taste
 Renal: oliguria (within 3 days) from proximal
tubular necrosis
 No report of Hg poisoning form button battery
ingestion
Pediatrics. 1992;89:747–757

21. Inorganic mercury
 Chronic toxicity
 GI: metallic taste, burning sensation in the mouth,
loose teeth, gingivostomatitis
 NS: tremor, neuroanesthesia, erethism (mad
hatter disease), emotional lability, tunnel vision,
insomnia
 Renal: reversible proteinuria, nephrotic syndrome
 Skin: acrodynia or pink disease

22. Pink disease (acrodynia)
Symptom complex associated with excessive sweating, tachycardia, irritability,
anorexia, photophobia, insomnia, tremors, paresthesias, decreased deep-tendon
reflexes, and weakness.

23. Thimerosal (inorganic Hg)
 0.1% thimerosal or 600 mcg/mL Hg
 A preservative in multi-dose vials in areas with in
adequate refrigeration
 No longer use in the US for routine childhood
vaccines since 2001
Global Alliance for Vaccines and Immunisation.Report to the GAVI Alliance Board Report of the Chief Executive Officer. 2012.
Immunol Allergy Clin North Am.2003;23:589–603.

24. Organic Hg compound
 Almost purely permanent neurologic disease
 Associated with methylmercury
 Lipophilic property
 Delayed neurotoxicity (weeks to months)
 Detected in breast milk (30% of blood conc.)

25. Source and route of organic Hg exposure
 Seafood
 FDA limit: 1 ppm for methyl mercury in fish
 EPA limit: 0.1 mcg/kg/day
 High blood concentration group in self-reported
high consumers of seafood
 High risk groups:
– pregnant women or who may become pregnant
– nursing mother
– young children

26. Minamata
 Decreased wt. and muscle tone
 Profound developmental delay
 Seizure
 Deafness and blindness
 Severe spasticity

27. Elemental Inorganic Organic
Primary route of
exposure
Inhalation Oral Oral
Primary tissue
distribution
CNS, kidney Blood (transient, acute) CNS, kidney, liver, blood,
hair
Kidney
CNS (delayed)
Clearance Renal, GI Renal, GI Methyl: GI
Aryl: renal, GI
Clinical effects
CNS Tremor Tremor, erethism Paresthesias, ataxia,
tremor, tunnel vision,
dysarthria
Pulmonary +++ – –
Gastrointestinal + +++ (caustic) +
Renal + +++ (ATN) +
Acrodynia + ++ –
Therapy BAL, DMSA BAL, DMSA DMSA (early)

28. Diagnostic testing for Mercury
Whole Blood 24-hour Urine Hair Clinical
Elemental/Inorganic (+) (++) (+) (+)
Acute, transient Confirm exposure Reflects past
exposure and
external adsorption
Poor correlation to
total body burden
(TBB)
Monitor chelation Early detection
Poor correlation to
TBB
Organic (++) (–) (+) (+)
Best reflects TBB
(N-acetyl-β-D-
glucosaminidase, β2-
microglobulin)
Fecal elimination Reflects past
exposure and
external adsorption
Poor correlation to
TBB
Reflects irreversible
CNS toxicity
Early detection

29. Hg concentration
 Overlap of Hg concentration found in the normal
population, asymptomatic exposed individuals
 No correlation between either whole blood or
urine mercury concentration and mercury toxicity
 1.0 μg/L or less for whole blood and 0.5 μg/L for
urine are generally considered to exposure in
non-poisoned individuals
Centers for Disease Control and Prevention. Fourth National Report on Human Exposure to Environmental
Chemicals. July 26, 2012. 2009.

30. General management for elemental Hg
 Aspiration: postural drainage, ETT suction
 Localized injection: surgical excision
 Sweep spilled Hg into tightly sealed container
 No vacuum for spilled Hg
 Broken CFL bulb: EPA guideline / local
requirements
www.pcd.go.th/info_serv/haz_lamp.htm
 Opening window to release vapor
 Adhesive tape to pick up fragments

31. General management for inorganic Hg
 Activated charcoal (AC): substantial adsorption
(800 mcg mercuric chloride: 1 g AC)
 Whole bowl irrigation with PEG
 Severe gastroenteritis
– Removal over endoscopic evaluation in suspected
penetrating GI mucosal injury

32. General management for organic Hg
 Chronic ingestion of contaminated food
 Aggressive decontamination: acute ingestion,
dermal exposure

33. Chelation (BAL, DMSA)
 Thiol groups in chelators compete with
endogenous sulfhydryl groups for the binding of
mercury
 Preventing inactivation of sulfhydryl-containing
enzymes and other essential proteins
 Indication:
– history of significant mercury exposure with
– Presence of typical symptoms of mercury poisoning
 Urine or blood concentration: unclear cases,
guide the duration of therapy

34. Summary
 3 major forms: elemental, inorganic and organic
 Large variety of clinical presentation
 Neurologic sequelae esp. from organic Hg
exposures : largely irreversible
 Promotion of public education and awareness
regarding
– Danger of Hg
– Avoidance
– Proper disposal