Exposure to chemical substances can cause adverse effects on the muscles, bones, and joints (Musculoskeletal Toxicity). The bone disorders arthritis, fluorosis, and osteomalacia are among the musculoskeletal diseases that can be induced by occupational or environmental toxicants. Rheumatoid arthritis is an autoimmune disease of the connective tissue characterized by joint inflammation and pain. It is often chronic and progressive, leading to deformities and disability. Prolonged exposure to silica and coal dust increases its incidence. Occupational exposure to fluoride can cause the skeletal disorder fluorosis, in which fluoride rather than calcium is deposited in bone. Osteomalacia is a painful, degenerative disease involving the gradual softening and bending of bones. It is caused by exposure to the musculoskeletal toxicant cadmium.