The following signs and symptoms are typically seen in the patients suffering from inorganic mercury poisoning:

• Sore throat
• Dyspepsia and pyrosis
• Abdominal colic 
• Vomiting
• Diarrhea
• Dehydration
• Desquamation of the skin
• Oliguria
• Peripheral neuropathy [7]
• Blindness
• Loss of balance and coordination
• Salivation
• Hypertension
• Seizures

The following diagnostic modalities and tests are preliminarily done for the work up of patients suffering from inorganic mercurial poisoning:

• Urine Test: Urine samples are taken from suspected patients and the concentration of mercury is determined. Mercurial concentration of at least 10 ug/L is a positive finding in mercury poisoning.
• Blood Test: In the same way, a serum mercurial concentration of at least 10 ug/L indicates inorganic mercury poisoning.
• Environmental Test: Samples from the environment of the patient (such as water source) are taken for mercurial analysis. Food sources like fishes from local water sources may also be investigated for mercurial accumulation. 
• Nerve Biopsy: Neural biopsy of nerve cells reveals progressive demyelination and axonal degeneration with inorganic mercury toxicity [8]. 
• Hair samples: A concentration of at least 1.2 mcg/g of mercury found in the hair shaft is indicative of heavy mercurial exposure [9]. 
• Cerebrospinal Fluid (CSF) Analysis: CSF analysis using spectroscopy can reveal the relative levels of mercury concentrations in the brain matter. 

The patients who are suspected of having mercury poisoning are usually treated as an emergency. The airways and breathing are primarily secured in the emergency room setting. Copious irrigation of the contaminated skin and the removal of the contaminated clothing are done. Patients with inorganic mercury poisoning benefit from a gastric lavage with activated charcoal. Chelating agents like thiol containing compounds and dimercaptosuccinic acid (DMSA) are arbitrarily used for symptomatic patients to unload the mercurial load in the serum [10]. In severe cases of toxicity with impending renal failure, hemodialysis affords an effective means of clearing the accumulated mercury from the system thereby preventing it from accumulating in the brain and kidneys.

The morbidity associated with mercury toxicity is usually dependent on the level of toxicity. In the severe case of Minamata Bay incident, a large number of patients fell into coma and consequentially died.

Mercury toxicity absorbed through the skin can have a delayed intoxication reaction in some patients [4]. Dietary mercurial toxicity is associated with dietary levels more than 0.5 mcg of mercury per kilogram body weight [5]. In general, dietary mercury toxicity is usually due to the ingestion of mercury contaminated fishes [6]. The majority of patients suffering from mercury poisoning develop neurologic and renal symptoms. Inorganic mercury and organic mercury toxicity can both be devastating to the fetus which can either lead to intrauterine death or growth retardation.

Inorganic mercury poisoning results from the ingestion and absorption of inorganic mercury and its active salts into the blood stream. Inorganic mercury can be found from the following sources:

• Thermometer
• Chemistry laboratory
• Batteries
• Folk medicines
• Red cinnabar minerals
• Disinfectants

The American Association of Poison Control Centers (AAPCC) have announced that in the year 2011, that there have been at least 1700 reports of patients with single exposure to mercury and its compounds [1]. Almost 44% were older than 19 years and 9% were children younger than 6 years. Among these cases, only 2.4% were noted to have moderate to severe clinical complications; while no mortalities were noted.

One of the most popular mercury poisoning occurred in the communities of Minamata Bay in Japan. The largest mass poisoning of mercury occurred in Iraq in the 1970's when 95,000 tons of mercury-based fungicide-treated grains were accidentally baked for consumption [2]. Although most of the patients were underdiagnosed, almost 6,000 Iraqi citizens were hospitalized because of the mishap and hundreds consequently died. In China, there were a significant number of cases of mercury toxicity and poisoning due to contaminated rice from mining activities [3].

Mercury in all its forms in nature can be ingested, absorbed through the skin or inhaled through the respiratory system. Inorganic mercury is usually not harmful in smaller quantities but exposure to large quantities of the element can have corrosive effects on the cells. The throat and the esophagus may consequently be irritated conveying a burning sensation. Stomach irritation can induce vomiting, abdominal colic and diarrhea. The fervent accumulation of inorganic mercury has been histologically proven to center in the kidneys and the brain matter. Irreversible kidney failure has been observed in severe mercury toxicities leading to coma and death. Neurologic symptoms like blindness, behavioral changes, headache, loss of coordination, and seizures are eminent in case of cerebral and cerebellar accumulation of the inorganic mercurial salts. 

Molecularly, mercurial accumulation irreversibly stops selenium-based enzymes and S-adenosyl-methionine which are needed for the catabolism of catecholamines. The consequent accumulation of the catecholamine epinephrine clinically leads to profuse sweating, tachycardia, salivation, and hypertension among affected patients.

Caution must be taken when handling pure mercury in the laboratory by using protective gloves. Old batteries must be disposed properly to prevent the accumulation of inorganic mercury in the environment. Skin disinfectants that contain mercury based compounds must be used judiciously to prevent the inadvertent accumulation of the element.

Inorganic mercury poisoning is a type of metal poisoning from the element mercury directly absorbed from the environment. Inorganic mercury represents the volatile and elemental form of mercury. It can occur in salted forms in nature like mercurous chloride and mercuric chloride.

Inorganic mercury may not be toxic in small doses; however, in large doses, it acts as a corrosive and causes gastrointestinal symptoms.

Inorganic mercury poisoning is a clinical condition in whiche there is a pathologic accumulation of inorganic mercury in the blood stream and some vital organs. Inorganic mercury can inadvertently be ingested or absorbed through the skin from environmental contaminants like battery effluents, laboratory discharges, and folk culture medicine preparations. 

The severity of inorganic mercury poisoning depends upon the amount of the mercury that is loaded into the system. Gastrointestinal symptoms like throat irritation, indigestion, vomiting, and diarrhea are seen. Neurologic signs of visual disturbances, loss of balance, and seizures may also be prominent. With severe toxicity, failure of kidneys may take place. Supportive care is imperative in the emergency setting in this kind of poisoning.

1. Bronstein AC, Spyker DA, Cantilena LR Jr, Rumack BH, Dart RC. 2011 Annual report of the American Association of Poison Control Centers' National Poison Data System (NPDS): 29th Annual Report. Clin Toxicol (Phila). Dec 2012; 50(10):911-1164.
2. Amin-zaki L, Majeed MA, Clarkson TW, Greenwood MR. Methylmercury poisoning in Iraqi children: clinical observations over two years. Br Med J. Mar 11 1978; 1(6113):613-6.
3. Feng X, Li P, Qiu G, et al. Human exposure to methylmercury through rice intake in mercury mining areas, Guizhou province, China. Environ Sci Technol. Jan 1 2008; 42(1):326-32.
4. Nierenberg DW, Nordgren RE, Chang MB, et al. Delayed cerebellar disease and death after accidental exposure to dimethylmercury. N Engl J Med. Jun 4 1998; 338(23):1672-6. 
5. EPA. Water quality criterion for the protection of human health: methylmercury. Environmental Protection Agency. Jan 2001; EPA-823-R-01-001.
6. ATSDR. Agency for Toxic Substances and Disease Registry. Toxicological Profile for Mercury. ATSDR. August 1997.
7. Langford NJ, Ferner RE (1999). "Toxicity of mercury" (PDF). Journal of Human Hypertension 13 (10): 651–6. doi:10.1038/sj.jhh.1000896. PMID 10516733.
8. Chu CC, Huang CC, Ryu SJ, Wu TN. Chronic inorganic mercury induced peripheral neuropathy. Acta Neurol Scand. Dec 1998; 98(6):461-5.
9. Li YF, Chen C, Li B, et al. Scalp hair as a biomarker in environmental and occupational mercury exposed populations: suitable or not?. Environ Res. May 2008; 107(1):39-44.
10. Forman J, Moline J, Cernichiari E, et al. A cluster of pediatric metallic mercury exposure cases treated with meso-2, 3-dimercaptosuccinic acid (DMSA). Environ Health Perspect. Jun 2000; 108(6):575-7.