Effects of exposure to portland cement dust on lung function in portland cement factory workers in khash, Iran
Portland cement is a light grey powder produced by crushing and grinding calcareous materials such as limestone, chalk and argillaceous materials such as; clay and shale, as a wet slurry or in a dry state. The mixture is calcined in a rotary kiln and the resulting clinker is finely ground. The product is composed largely of calcium silicates, calcium aluminates, calcium sulfates, oxides of sodium and potassium and calcium-alumino-iron compounds (Burgess, 1981). Other constituents are then added, depending on the desired concrete properties. Hexavalent chromium may also be present in the cement. Exposure to Portland cement dust has long been associated with the prevalence of respiratory symptoms and varying degrees of airway obstruction in man. Apart from respiratory diseases, it was also found to be a cause of lung and laryngeal cancer, gastrointestinal tumors and dermatitis (Vestbo and Rasmussen, 1990; Rasmussen et al., 1990; Jakobsson et al., 1993; Yang et al., 1996; AbuDhaise et al., 1997; Noor et al., 2000; Algranti et al., 2001; Al-Neaimi et al., 2001; Laraqui et al., 2001; Stern et al., 2001).