Occupational Health Surveillance Program, Occupational Disease and Injury Services (ODIS), Division of Environmental and Occupational Health, New Jersey Department of Health and Senior Services (NJDOHSS)
Silicosis, a disabling disease of the lung, is a classic example of an occupational disease that can and should be prevented. The key to prevention is identification of workplaces with potential for silica exposure, controlling exposures, and then periodic monitoring to assure that exposure levels are below recommended limits. Silicosis, which is caused by inhalation of silica dust, is one of a class of diseases called pneumoconiosis or "dust disease of the lung." Inhaled particles of crystalline silica dust promote the formation of scar tissue that can lead to disability, or often death. Symptoms of silicosis usually do not appear until more than 20 years after the exposure. Silicosis is also associated with an increased risk for tuberculosis. Silicosis has been a public health concern in New Jersey because of the many silica-using industries in the state, including: foundries, potteries, glass manufacturing, and sand and stone mining. Although mortality from silicosis and silico-tuberculosis has declined since the 1940's, significant numbers of workers still remain exposed to hazardous levels of silica dust in New Jersey. Based on the number of employees in industries where potential silica hazards may exist, it is estimated that 25,572 workers may be exposed currently in our state. The Silicosis Surveillance System In response to public health concern with silicosis in New Jersey, the Department of Health and Senior Services (DHSS) developed an active silicosis surveillance system with support from the National Institute for Occupational Safety and Health (NIOSH), starting in 1984. The system was designed to describe the magnitude of silicosis in the state and characteristics of cases, and to implement and evaluate intervention strategies for reducing silica exposure in New Jersey workplaces. To meet these objectives, the DHSS maintains a register of reported silicosis cases and collects sufficient medical and occupational data on reported cases to assess whether cases meet an epidemiologic case definition. In addition, industrial hygiene evaluations are conducted at workplaces currently using silica to prevent silicosis in the future among currently exposed workers. These evaluations assess worker exposures by means of air sampling, measure the performance of engineering controls such as ventilation and dust collection systems, and determine the effectiveness of respiratory protection equipment. Cases of silicosis are identified primarily from hospital discharge data, although some cases have come from mortality data, physician reports, and medical screenings at silica-using worksites. Interviews with cases or their next-of-kin are conducted to collect or verify demographic information provided by the case report; and to obtain information about the individual's work history including all company names, industry types, years of employment, occupations, and job duties. Medical records are obtained and reviewed by an occupational medicine physician, and chest x-rays are interpreted by a NIOSH-certified "B-reader." Collected information is used to determine if the individual's condition meets the epidemiologic case definition for silicosis (see page 5) and to determine names of companies where silica exposure took place. Companies are then contacted to determine if there is current silica exposure at the site. If current silica exposure potentially poses a risk to employees, then DHSS industrial hygienists conduct a site visit to evaluate the risk and make recommendations for controlling silica dust hazards.