Mercury poisoning results from exposure to elevated levels of mercury, a naturally occurring heavy metal. When the body accumulates too much mercury, it becomes toxic, leading to various adverse health effects.
Forms of Mercury and Exposure Pathways
Mercury exists in several forms, each with distinct exposure pathways.
Elemental mercury, a silvery, liquid metal at room temperature, readily vaporizes into an invisible, odorless toxic vapor. Exposure to this form commonly occurs through inhaling vapors from broken household items like thermometers or fluorescent light bulbs. Dental amalgam fillings also release small amounts of elemental mercury vapor. Ingesting elemental mercury, however, is generally less harmful as it is poorly absorbed by the digestive system.
Inorganic mercury compounds are formed when mercury combines with other elements, such as chlorine or oxygen, often existing as salts. These compounds are typically encountered through ingestion, such as from certain industrial processes or traditional herbal preparations. Historically, some skin-lightening creams also contained inorganic mercury, leading to exposure through dermal absorption.
Organic mercury, primarily methylmercury, is created when microorganisms in water and soil transform inorganic mercury. This form is the most common source of human exposure, largely due to its accumulation in the food chain. Fish and seafood absorb methylmercury, and larger, predatory fish tend to have higher concentrations due to biomagnification. Consuming these contaminated aquatic foods is the main route of organic mercury exposure.
Recognizing the Symptoms
The symptoms of mercury poisoning can vary considerably depending on the specific form of mercury, the amount of exposure, the method of contact, and the duration of the exposure.
Neurological Symptoms
Neurological symptoms are frequently observed with mercury exposure. Individuals might experience tremors, often seen as uncontrollable shaking, along with memory problems, irritability, and changes in mood such as anxiety or depression. Coordination difficulties, including an unsteady walk, and sensations of numbness or tingling, especially in the hands, feet, or around the mouth, are also reported. Problems with speech, hearing loss, and visual disturbances like peripheral vision constriction or double vision can also occur.
Digestive Issues
Digestive issues can arise, especially with acute exposure to elemental mercury vapor or ingestion of inorganic mercury. Symptoms may include nausea, vomiting, diarrhea, and abdominal pain. A metallic taste in the mouth, along with swollen or bleeding gums, can also be present. With inorganic mercury ingestion, a burning sensation in the stomach and throat, potentially accompanied by severe abdominal pain or even bloody diarrhea, may develop.
Respiratory Symptoms
Respiratory symptoms are common following acute inhalation of elemental mercury vapor. These can manifest as a cough, shortness of breath, or chest tightness and pain. A burning sensation in the lungs may also be noted. In severe instances, these respiratory effects can progress to more serious conditions like pulmonary edema or respiratory distress.
Kidney Involvement
Kidney involvement is a significant concern, as mercury tends to accumulate in the kidneys. This can lead to kidney dysfunction, sometimes indicated by changes in urine output or the presence of protein in the urine. In some cases, acute renal failure can develop.
Skin Manifestations
Skin manifestations are another potential sign, with rashes, skin discoloration, and swelling being reported. In children, chronic exposure, often to inorganic mercury, can lead to a condition known as acrodynia, or “pink disease.” This condition is characterized by painful, pink discoloration of the hands and feet, increased sensitivity to light, irritability, and excessive sweating. Hair loss and nail loss may also accompany acrodynia.
Oral and Dental Symptoms
Oral and dental symptoms can include gingivitis, inflammation of the gums, and a persistent metallic taste. Swollen or bleeding gums and even tooth loss can occur with significant exposure. Stomatitis, which is inflammation of the mouth, along with foul breath, are also possible indicators.
When to Seek Medical Care
If mercury exposure is suspected, seeking professional medical evaluation is important. Symptoms of mercury poisoning can sometimes resemble those of other health conditions, making a timely and accurate diagnosis by a healthcare provider beneficial.
A healthcare provider can assess an individual’s symptoms and consider their history of potential exposure, including occupational background, hobbies, and dietary habits. This comprehensive assessment helps determine if mercury toxicity is a likely cause of the observed health issues. Prompt action is advisable, as prolonged exposure or high levels of mercury can lead to lasting damage to the nervous system and kidneys.