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New Jersey Silica Partnership.
Occupational Health Surveillance Update 2001 Feb; :1-3
The Occupational Health Surveillance Program of the New Jersey Department of Health and Senior Services (DHSS) has received funding since 1988 from the National Institute for Occupational Safety and Health (NIOSH), under their Sentinel Event Notification System for Occupational Risks (SENSOR) Program, to conduct disease surveillance for silicosis. Silicosis is a disabling, non-reversible, and sometimes fatal lung disease caused by breathing dust containing extremely fine particles of crystalline silica. In addition to silicosis, inhalation of crystalline silica particles has been associated with other lung diseases, such as bronchitis, tuberculosis, and lung cancer. The DHSS maintains a register of reported silicosis cases, and collects the medical and occupational data necessary to determine if a case meets the epidemiologic case definition for silicosis. Industrial hy- giene follow-up of identified worksites is conducted by DHSS staff who evaluate the potential for exposure to silica and recommend control measures to prevent exposure. In January, 1999, the Surveillance Program joined with other agencies and groups to form a partnership to address growing concerns about silica exposure to New Jersey road and highway construction workers. The DHSS SENSOR project had previously identified 11 cases of confirmed or probable silicosis among workers in the road construction and elevated highway construction industries (SICs 1611 and 1622, respectively). Road building materials such as concrete, asphalt, and masonry products contain silica sand, as well as other forms of crystalline silica. There are numerous job tasks with the potential for silica exposure in road construction and repair workers. A typical bridge deck repair job proceeds as follows: 1) temporary traffic patterns are set up using traffic cones or concrete barriers, 2) the top layer of asphalt is removed using a milling machine, 3) the concrete surface is remilled to impart a smoother profile, 4) boundary areas where the milling machine can't reach are profiled with a scabbler, 5) millings and dust are cleaned up using a vacuum/ sweeper/dust collector truck, 6) an inspector identifies and marks the areas in need of repair, 7) the perimeters of the repair areas are sawcut to the depth of the re-bar, 8) jackhammers are used to chip away the concrete from around the re-bar, 9) repair areas are cleaned out using compressed air, 10) repair areas are patched, 11) bridge deck is resurfaced with asphalt, 12) repaired bridge deck is reopened to traffic. Some repair jobs require that entire sections of the road be cut and removed. Replacing the sections requires that the road surfaces adjoining the repair area are drilled to accept reinforcement dowels. A major component of the New Jersey Silica Partnership was the collection of air sampling data to evaluate exposures associated with various tasks (See photos on page 4) performed in road construction and repair. The DHSS, as the lead partner, developed a sampling strategy to be used at the worksites of the ten partner contractors. Samples were collected according to NIOSH Method 7500 and analyzed by the Occupational Safety and Health Administration's (OSHA) accredited laboratory according to OSHA Method ID-142. Eleven sets of samples were collected at nine different worksites involving seven of the ten partner contractors. A total of 53 samples were collected for seven different work tasks, namely, jackhammering, concrete sawing, concrete milling, concrete clean-up, dowel drilling, asphalt milling, and asphalt clean-up. The sample results were compared to the OSHA Permissible Exposure Limit (PEL) to determine if overexposures were occurring. The percentage of silica contained in the dust of an air sample is used to calculate the PEL for each respective sample. Air sampling results and percent silica content associated with the road-repair tasks are presented. Engineering controls, such as water or local exhaust ventilation with filtration, were not used on any of the sampled tasks, except for asphalt milling, where water from a built-in reservoir was applied to the cutter drum. Sampling that has been performed by other researchers on various concrete, stone, and masonry jobs involving drilling and sawing have demonstrated the efficacy of water use in reducing dust levels to which workers are exposed. Various reasons cited by contractors for not using water for dust control include difficulty in clean-up, hazard of slippage, and difficulty in control of runoff.
Chemical-composition; Chemical-properties; Respiratory-irritants; Respiratory-system-disorders; Pulmonary-system; Pulmonary-system-disorders; Pulmonary-function; Lung-disease; Lung-irritants; Lung; Exposure-levels; Risk-factors; Silicosis; Silica-dusts; Silicates; Diseases
New Jersey Silica Partnership
New Jersey Department of Health and Senior Services
Page last reviewed: April 12, 2019
Content source: National Institute for Occupational Safety and Health Education and Information Division