Overview
Mercury is a heavy metal with an atomic mass of 200.59 and has no known essential role in normal human physiology. Environmental exposure occurs through natural emissions, burning of fossil fuels, waste disposal, mining activities, and industrial processes. It exists in organic, inorganic, and elemental forms, each with different absorption patterns, tissue distribution, and toxicity profiles. Organic mercury, especially methylmercury, bioaccumulates in the food chain and readily crosses the blood-brain barrier and placenta, making it particularly harmful. Measurement of this in blood, urine, hair, or nails helps assess the degree, type, and timing of exposure, supporting diagnosis and management of toxicity.
Symptoms
Its toxicity primarily affects the nervous system, kidneys, immune system, and gastrointestinal tract. Neurological symptoms include tremors, impaired coordination, memory loss, insomnia, mood changes, emotional instability, headaches, and sensory disturbances affecting vision and hearing. Chronic exposure may lead to cognitive decline, neuromuscular dysfunction, and behavioral changes. In severe cases, paralysis and profound neurological impairment can occur. Its exposure during pregnancy poses a significant risk to fetal development, potentially causing long-term neurodevelopmental deficits in children.
Causes
Mercury exposure may result from consumption of contaminated fish and seafood, occupational exposure in mining, dentistry, manufacturing, or laboratory settings, and use of mercury-containing products such as dental amalgams, skin lightening creams, or certain industrial chemicals. Elemental mercury is mainly absorbed through inhalation, while organic mercury is efficiently absorbed through the gastrointestinal tract. Inorganic mercury compounds primarily accumulate in the kidneys and are associated with renal toxicity. The absorbed distributes throughout the body within hours and has a prolonged biological half-life, leading to cumulative toxicity with repeated exposure.
Risk Factors
Individuals at higher risk include workers in industries using it, people with high seafood consumption, individuals living near industrial or mining areas, and patients with impaired renal function. Pregnant women and young children are especially vulnerable due to the ability to cross the placenta and affect brain development. Chronic low-level exposure may go unrecognized without targeted testing, as symptoms can overlap with other neurological or systemic disorders. Improper sample collection, recent dietary intake of seafood, or continued use of supplements can interfere with accurate assessment.
Prevention
Prevention of toxicity focuses on minimizing exposure and ensuring early detection in at-risk populations. Avoiding excessive consumption of high mercury seafood, following occupational safety guidelines, and limiting use of mercury-containing products are key preventive measures. Before testing, patients should discontinue non-essential supplements and avoid seafood for several days to prevent false elevation. Proper sample collection using metal-free containers and appropriate analytical methods ensures reliable results. Early identification and monitoring of these levels support timely intervention, reduce the risk of long-term complications, and guide effective management of both acute and chronic mercury exposure.
