Intoxication by mercury and its compounds

Mercury in inorganic form
A silvery lustrous liquid metal, it evaporates at room temperature.

Salts
The most dangerous are soluble Hg 2+ salts (mercuric chloride, nitrate).

Professional exposure
Production of mercury measuring instruments, batteries, dental amalgams (with silver), formerly used in dermatology and as a diuretic.

Etiopathogenesis
We must distinguish elemental mercury and salts.

Elemental mercury :


 * most often by inhalation (80% is absorbed);
 * high exposure – damages the respiratory system ( pneumonia, edema);

target organs – brain, kidneys , chronic inhalation is the worst for the CNS , it reaches the brain in a moment, it is lipophilic;


 * in the CNS it is then oxidized to divalent mercury, which no longer passes through the barrier → accumulation;
 * accumulates mainly in the cerebral cortex and cerebellum and in the BG;
 * outside the CNS, elemental mercury is also oxidized by catalase (mainly in eras) and interferes with SH groups;
 * it then accumulates in the cortex of the kidneys, binds to metallothionein (which protects the kidneys), kidney damage only occurs when it is saturated (mainly damages the proximal tubule → nephrotic sy), soluble mercury salts – by inhalation in the form of dust, but mainly they can be absorbed from the GIT and cause severe acute poisoning, up to 90% is resorbed from the GIT, the cause of death is acute kidney failure.

Chronically – by skin application of ointments with Hg, ingestion of alimentary mercury – e.g. from a thermometer by small children, poor absorption in the GIT (5%) → there is no risk of poisoning,


 * but it has a strong laxative effect;
 * kinking of a rectal thermometer with laceration tissue - hard-to-remove mercury may enter - poisoning;
 * iv application of metallic mercury – it does not cause poisoning, but there is a risk of embolization;
 * excretion of mercury is slow, due to binding to SH, mercury can be detected in hair and nails.

Clinical picture

 * Acute - rarely - either by inhalation with elemental mercury or after with salts;
 * by inhalation – in a closed space with high mercury vapor tension, cough, shortness of breath, fever, pneumonia, pulmonary edema;
 * oral salts – vomiting, tenesmus, necrosis of the GIT mucosa, diarrhea with mucosal lines, proteinuria, hematuria, oliguria, kidney failure.


 * Chronic - in both types, a triad can appear - gingivitis, tremor , erethism;
 * gingivitis – gingivitis, salivation, tooth loss;
 * tremor – of cerebellar origin, gentle, then pronounced intentional tremor (initially limbs, then eyelids, lips), then ataxia, fasciculations in muscles;
 * erethism – toxic organic psychosis – anxiety, shyness, nervousness, quarrelsomeness, emotional lability, memory disorders, concentration, depression, sleep rhythm inversion (sometimes reminiscent of schizophrenia), less often – kidney damage.

Investigation methods

 * An increase in the concentration of mercury in the blood → indicates recent exposure (acute poisoning),
 * increased values ​​of mercury in the urine → rather indicate chronic intoxication (but they fluctuate significantly even during the day),
 * better predicts the amount of mercury in the urine after administration of a chelating antidote,
 * proteinuria – indicates kidney damage.

Therapy
Acute inhalation, with ingestion of salts – PP – milk or egg white (forms insoluble precipitates of Hg-albuminate), excretion of mercury in urine – chelating agent – ​​DMPS, dimercaptopropane sulfonate (dimercaptopropanol was previously used – BAL (British anti-Lewisine)),


 * with anuria - hemodialysis, assessment of professionalism - with acute inhalation, professionalism is usually obvious,
 * alimentary salt poisoning is rather suicide ,
 * chronic occupational poisonings are a rarity today.

Mercury in organic form
Alkyl compounds (methyl and ethyl mercury):


 * These are highly toxic compounds, central neurotoxicity is typical.
 * They cause central deafness, narrowing of the visual field, cerebellar symptoms, pyramidal symptoms, extrapyramidal symptoms, renal tubule necrosis.

Aryl compounds (phenylmercury):


 * Cause mild proteinuria, dermatitis,
 * they were previously used as fungicides.

In 1953 in Minamata Bay – mercury from the factories got into the fish, they incorporated it into methylmercury. The first symptoms were observed in cats, then fishermen with families (central deafness, dysarthria , ataxia ). These compounds have been banned in our country.

related articles

 * Intoxication by lead and its compounds
 * Intoxication with methemoglobinizing substances