Heavy metals

Heavy metals are a group of minerals that can be classified as metals or metalloids. These minerals differ from regular metals in that they have a higher density and have the ability to easily (bio)accumulate inside tissue. Build-up of these heavy metals can cause a wide range of effects from decreased mental function, to kidney, liver, and lung damage.

Heavy metals appear in or on objects in different ways. Lead and cadmium were often used to colour the enamel of medals and badges. A similar process used heavy metals to colour textiles. A well-known example is the use of arsenic or chromium to give textiles a green colour. Moreover, heavy metals can also be present as such within a collection, more specifically in the form of plates, bowls, metallic constructions, etc.

1. Arsenic | Arsenic (As) is a metalloid found in the Earth’s crust. It can be found in combination with other minerals.
2. Lead | Lead (Pb) is a metal that occurs naturally combined with sulfur and rarely in its pure metallic form. Lead has a blue-gray colour and is soft and malleable. 
3. Antimony | Antimony (Sb) is a metalloid that occurs naturally combined with sulfur (Sb₂S₃ – stibnite). Antimony has a silvery-white colour.

Arsenic can enter the body through inhalation, ingestion, skin contact or the eyes. Inhalation of arsenic can cause irritation of the nose and throat. Skin contact can lead to irritation, rashes, burns, and even the loss of skin pigment. Contact with the eyes can also cause irritation and burns. Arsenic is recognized as a carcinogen. Long-term exposure to arsenic can lead to lung cancer or skin cancer.

Arsenic was used for a variety of reasons in the past: as a pesticide, as an insecticide, to make pigments, during the process of taxidermy, as medication, and to bleach the skin. For the heritage sector this means that arsenic can be found in objects such as fake flowers, textiles, wallpaper, book covers, and animals treated for taxidermy.

Lead has been incorporated in different objects, but can also be found in elements of a building such as the roof and pipes or drains. Lead can enter the body through digestion, inhalation or the skin, circulates through the system until it is excreted or stored in the bones, from where it can spread throughout the body. Lead can also be stored in the teeth, the kidneys, the brain, the spleen and the liver. The possible consequences of high lead exposure in adulthood are higher blood pressure, anaemia, and kidney disease.

Lead can also pose a health risk for pregnant women and children. In pregnant women, excessive exposure to lead can cause miscarriages. Lead exposure can hamper brain development in unborn and young children.

Antimony oxides are fire retardant and therefore used in textiles, plastics, papers, and paints, whereas antimony trisulfide (Sb₂S₃) is used in the production of explosives and pigments.

Exposure to antimony and its compounds can cause respiratory irritation, increased blood pressure, abdominal pain, ulcers, spontaneous abortions, and is possible carcinogenic.

Table of content

Heavy metals | Old pesticides  | Medical equipment  | Chemical warfare equipment  | Asbestos