A Comprehensive Assessment of Exposures to Respirable Dust and Silica in the Taconite Mining Industry

Details

• Personal Author:
  Alexander BH ; Hwang J ; Mandel JH ; Ramachandran G ; Raynor PC
• Description:
  This study assessed the present-day levels (year 2010-2011) of exposure to respirable dust (RD) and respirable silica (RS) in taconite mines and evaluated how the mining process influences exposure concentrations. Personal samples (n = 679) were collected to assess exposure levels of workers to RD and RS at six mines in the Mesabi Iron Range of Minnesota. The RD and RS concentrations were measured using the National Institute for Occupational Safety and Health (NIOSH) 0600 and NIOSH 7500, respectively. Between-mine, between-SEG (similar exposure groups), within-SEG, and within-worker components of variability for RD and RS exposures were estimated using a two- or three-way nested random-effects ANOVA model. The majority of RD concentrations across all mines were below the Mine Safety and Health Administration (MSHA) Permissible Exposure Limit (PEL). The highest concentrations of RD were often observed in either the Pelletizing or Crushing departments, which are inherently dusty operations. With a few exceptions, the concentrations of RS in the crushing and concentrating processes were higher than those in the other mining processes, as well as higher than the American Conference of Governmental Industrial Hygienists (ACGIH) Threshold Limit Value (TLV) for RS. The magnetic separation and flotation processes in the concentrating department reduced the levels of RS significantly, and lowered the percentage of quartz in RD in the pelletizing department. There was little variability among the six mines or between the two mineralogically distinct zones for either RD or RS exposures. The between-SEG variability for RS did not differ substantially across most of the mines and was a major component of exposure variance. The within-SEG (or between-worker) variance component was typically the smallest because in many instances one worker from a SEG within a mine was monitored multiple times. Some of these findings were affected by the degree of censoring in each SEG and mine, characteristics of the taconite rock, seasonal effects during sampling, or the tasks assigned to each job in that mine. [Description provided by NIOSH]
• Subjects:
  Dust Minerals Mining Occupational Exposure Occupational Health Quartz Safety Silicon Dioxide
• Keywords:
  Author Keywords: Exposure Assessment Exposure Assessment Mineral Processing Mining Industry Occupational Exposure Quartz Dust Respirable Dust Respirable Silica (quartz) Taconite Variance Components
• ISSN:
  1545-9624
• Document Type:
  Text
• Funding:
  Grant
• Genre:
  Journal Article
• Place as Subject:
  Maryland ; Minnesota ; OSHA Region 3 ; OSHA Region 5
• CIO:
  National Institute for Occupational Safety and Health (NIOSH)
• Topic:
  Workplace Safety & Health
• Location:
  North America
• Pages in Document:
  377-388
• Volume:
  14
• Issue:
  5
• NIOSHTIC Number:
  nn:20064098
• Citation:
  J Occup Environ Hyg 2017 May; 14(5):377-388
• Contact Point Address:
  Gurumurthy Ramachandran, Department of Environmental Health and Engineering, Bloomberg School of Public Health, Johns Hopkins University, E 6634, 615 N. Wolfe Street, Baltimore, MD 21205
• Email:
  gramach5@jhu.edu
• CAS Registry Number:
  Quartz (SiO2) (CAS RN 14808-60-7) ; Taconite (CAS RN 12249-26-2)
• Federal Fiscal Year:
  2017
• Performing Organization:
  University of Minnesota Twin Cities
• Peer Reviewed:
  True
• Start Date:
  20050701
• Source Full Name:
  Journal of Occupational and Environmental Hygiene
• End Date:
  20250630
• Collection(s):
  National Institute for Occupational Safety and Health
• Main Document Checksum:
  urn:sha-512:4f240d310b4a796568814aa9de420dfb4734ea2582ed83ecd7f18ac554d5944b0c0332b198203916b4d6ee92daf7c111578d81c8e54df3ce63c777ed4cd7c80a
• Download URL:
  https://stacks.cdc.gov/view/cdc/222617/cdc_222617_DS1.pdf
• File Type:
  [PDF - 1.12 MB ]