Grout -- comprised of Portland cement, aggregates, limestone and often silica -- poses a health hazard through inhalation and skin contact. The dust can also cause eye irritation and even blindness. Exposure may result in short- or long-term physical problems, such as burns or respiratory disorders. The substance carries a significant risk when wet or dry.

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Regularly clean the grout between tiles to reduce the chance of black mold growing.

Inhalation

Silica can comprise up to 25 percent of grout's ingredients. Inhalation of silica crystals can severely scar the lungs, which can lead to lung cancer and silicosis. Chronic silicosis usually occurs after 20 or more years of exposure to the dust particles. The person will experience swollen lymph nodes and lung tissue, making breathing difficult. A person exposed to large amounts of silica can suffer from accelerated silicosis within 5 to 15 years of exposure. Acute silicosis occurs suddenly after exposure to excessively large quantities of the dust. The lungs become inflamed and filled with water, and the sufferer experiences shortness of breath and oxygen deprivation. No cure exists for silicosis. Ailicosis sufferers often require a lung transplant. Sufferers also contract tuberculosis easily.

Skin Exposure

Highly caustic, grout can cause skin burns. The alkaline substances within the grout can penetrate the skin layers. First, second, or third degree burns can occur on skin exposed to wet grout. The sufferer will often require hospitalization and skin grafts to repair the burn damage. Skin exposed to wet grout often does not feel pain initially. Pain usually occurs only after the skin has been severely damaged. Even short term exposure to wet grout often causes skin irritation and inflammation.

Allergies

People who regularly work with grout often develop an allergic reaction to the substance, known as allergic contact dermatitis. The allergy can occur immediately after exposure or may take many years to develop. If a worker develops an allergy to the grout, only a short-term exposure to the substance will cause a severe skin reaction. Redness, inflammation and pain will occur when a person becomes allergic to the substance.

Black Mold

Grout is often used to fill in the spaces between tiles in bathrooms and kitchens. Over time, black mold often develops on the grout. The mold poses a significant health risk to humans and pets. Sensitive individuals can suffer respiratory problems from black mold exposure. Scrub the grout between tiles at least once per week with a mold-reducing cleaner to keep black mold from developing. If black mold develops on the grout, call a professional grout cleaning service to safely remove the mold.