Clinical manifestations of chronic mercury poisoning

Mercury is a liquid metal that not only evaporates but is also toxic. Mercury has a wide range of uses. The thermometers we commonly use contain mercury. In addition, pigments, medicines, lighting lamps, and instruments all contain varying degrees of mercury. If you are engaged in this kind of work, you may suffer from chronic poisoning from inhaling mercury evaporated from the air. So, what are the clinical manifestations of chronic mercury poisoning? Let’s take a look below.

Causes

Because mercury is highly fluid and easily evaporates at room temperature, mercury poisoning is a common occupational poisoning. It mainly occurs from long-term inhalation of mercury vapor or mercury compound dust during production. Industrial poisoning is seen among workers in mercury mining, amalgam smelting, gold and silver extraction, vacuum mercury, lighting, instruments, thermometers, dental fillings, fulminate of mercury, pigments, pharmaceuticals, nuclear reactor coolants and atomic radiation protection materials.

Mercury is widely present in nature. Various natural phenomena can cause mercury to circulate continuously from the surface through the atmosphere, rain, snow and other links, and can be absorbed by animals and plants. Human production activities can significantly increase mercury pollution to the environment. Although the proportion of this type of man-made pollution is not large, the emissions are concentrated, so the harm is far more serious than natural pollution. Mercury-containing wastewater pollution of rivers, lakes and oceans can cause pollution-related diseases such as Minamata disease.

Short-term (>3 to 5 hours) inhalation of high-concentration mercury vapor (>1.0 mg/m3) and oral ingestion of large amounts of inorganic mercury can cause acute mercury poisoning; taking or applying folk remedies containing mercury can cause subacute mercury poisoning; occupational exposure to mercury vapor often causes chronic mercury poisoning.

Chronic mercury poisoning

(1) Neuropsychiatric symptoms include dizziness, headache, insomnia, frequent dreams, forgetfulness, fatigue, lack of appetite and other manifestations of mental weakness, frequent palpitations, sweating, positive skin scratch test, decreased libido, menstrual disorders (female), and then mood and personality changes, such as irritability, moodiness, irritability, crying, timidity, shyness, depression, loneliness, suspicion, inattention, and even hallucinations, delusions and other mental symptoms.

(2) In the early stages of stomatitis, the gums become swollen, sore, and easily bleed; the oral mucosa ulcers, salivary gland enlargement, increased saliva, and bad breath are followed by gum atrophy, loose teeth, and tooth loss. Those with poor oral hygiene may have a "mercury line" (a blue-black line about 1 mm long formed by the mercury secreted by the salivary glands combining with hydrogen sulfide produced by the decay of oral debris to form mercury sulfide that is deposited under the gingival mucosa).

(3) Tremor initially occurs when the hands tremble while threading a needle, writing, or holding chopsticks. The tremor is inaccurate and intentional, and gradually spreads to the limbs. The patient's eating, dressing, walking, riding a bicycle, and climbing are affected. There are difficulties in pronunciation and articulation. The tremor is relatively alleviated when the patient is engaged in habitual work or is not being noticed. Electromyography may show peripheral nerve damage.

(4) Renal manifestations are generally not obvious. A few patients may experience low back pain, proteinuria, and red blood cells may be seen under urine microscopy. Clinical cases of tubular nephritis, glomerulonephritis, and nephrotic syndrome are rare. Generally, recovery can be achieved after removal of mercury and treatment. Some patients may have enlarged liver and abnormal liver function.