Membranous nephropathy from exposure to mercury in the fluorescent-tube-recycling industry.

Mercury is a silvery white liquid metal that is volatile at room temperature due to its high vapour pressure. It exists in different oxidation states and can form a number of compounds. Mercury and its compounds can be absorbed into the human body by inhalation, ingestion, and through the skin. It is toxic when certain threshold values are exceeded. Acute toxicity is due to the inactivation of enzymes by the heavy metal, which leads to interstitial pneumonitis, ulcerative gastro-enteritis, or tubular necrosis, depending on the route of exposure. Long-term mercury poisoning affects mainly the central nervous system and the kidneys. In the latter case the nephrotoxicity is usually manifested as membranous glomerulonephritis (MGN) with nephrotic syndrome. Since 1920, numerous cases of nephrotic syndrome due to long-term contact with mercury and mercury compounds have been reported. Mercurial diuretics (Mersalyl), teething powders for young children, and mercury-containing ointments for psoriasis were the main sources of exposure in medicine w1,2x. In 1962, MGN was demonstrated by renal biopsy in five cases of nephrotic syndrome due to psoriasis ointments containing mercury w3x. MGN due to skin-lightening creams containing mercury was reported last in 1987 w4x. In industry, mercury is still used in gold mines, in chlor-alkali plants, and in the manufacture of batteries. In daily life, it occurs in technical and control instruments. Here we report for the first time two cases of membranous nephropathy due to occupational exposure to mercury vapour in the fluorescent-tuberecycling industry.