Which statement best describes mercury forms and absorption?

• A. Organic mercury forms are lipophilic and readily absorbed; elemental and inorganic forms are less
• B. Elemental mercury is best absorbed
• C. Inorganic mercury salts are lipophilic
• D. All mercury forms are equally absorbed

Answer: (A)

Mercury comes in forms that behave very differently in the body because of their chemical properties, especially lipophilicity. Organic mercury compounds are highly lipophilic, so they cross cell membranes easily and are absorbed efficiently after ingestion. In contrast, elemental mercury is not readily absorbed from the gastrointestinal tract, though it is absorbed well when inhaled as vapor through the lungs. Inorganic mercury salts are not lipophilic, so they pass into the bloodstream poorly when swallowed and are less readily absorbed orally. This combination—organic forms being readily absorbed due to lipophilicity, with elemental and inorganic forms showing much lower oral absorption—best describes how mercury forms differ in absorption and helps explain differences in exposure risk and toxicokinetics.