Respiratory manganese particle size, time-course and neurobehavioral outcomes in workers at a manganese alloy production plant

Details

• Personal Author:
  Baldwin M ; Bouchard MF ; Bowler R ; Mergler D ; Park RM
• Description:
  The progression of manganism with chronic exposure to airborne manganese (Mn) is not well understood. Here, we further investigate the findings on exposure and neurobehavioral outcomes of workers from a silico- and ferromanganese production plant and non-exposed workers from the same community in 1990 and 2004, using a variety of exposure metrics that distinguish particle size and origin within the range of respirable airborne exposures. Mn exposure matrices for large respirable particulate (Mn-LRP, dust) and small respirable particulate (Mn-SRP, fume), based on process origins, were used together with detailed work histories since 1973 (plant opening), to construct exposure metrics including burdens and cumulative burdens with various clearance half-lives. For three out of eight 1990 neurobehavioral tests analyzed with linear regression models, duration of Mn exposure was the best predictor: Luria-Nebraska Neuropsychological Battery - Motor Scale, Trail-Making B and Finger Tapping. The Luria-Nebraska Motor Scale had the strongest association (t - 5.0, p < 10-6). For outcomes on three other tests, the duration and Mn-SRP metrics were comparable: Trail Making Test A, Cancellation H and Stroop Color-Word Test (color/word subtest). Delayed Word Recall was best predicted by Mn-SRP (based on square root or truncated air-concentrations). The Word score on the Stroop Color-Word Test was the only outcome for which Mn-LRP was the leading predictor (t = -2.92, p = 0.003), while performance on the WAIS-R Digit Span Test was not significantly predicted by any metric. For outcomes evaluated in both 1990 and 2004, a mixed-effect linear regression model was used to examine estimates of within- individual trends. Duration and Mn-SRP were associated with performance on the Luria-Nebraska Motor Scale, as well as with other outcomes that appeared to have both reversible and progressive features, including Trail Making A and B, Cancellation H and Delayed Word Recall. With the mixed-effect model, Digit Span exhibited a significant irreversible association with exposure duration (t = -2.34, p = 0.021) and Mn-SRP (square root; t = -2.38, p = 0.019) metrics. The strong prediction using duration of exposure is consistent with effective homeostatic regulation of tissue-level Mn in the observed exposure range of respirable Mn (<0.2 mg/m3). [Description provided by NIOSH]
• Subjects:
  Air Pollutants, Occupational Dust Irritants Lung Lung Diseases Manganese Occupational Health Particulate Matter Respiratory System Respiratory Tract Diseases Safety Workplace

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• Keywords:
  Airborne-dusts Airborne-particles Author Keywords: Manganese Burden Exposure-levels Exposure Duration Fume Half-life Homeostasis Manganese-compounds Particulates Pulmonary-disorders Pulmonary-function Pulmonary-system Pulmonary-system-disorders Q2 Cumulative Exposure Respiration Respiratory-irritants Respiratory-system-disorders Work-environment Workers

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• ISSN:
  0161-813X
• Document Type:
  Text
• Genre:
  Journal Article
• Place as Subject:
  California ; Ohio ; OSHA Region 5 ; OSHA Region 9
• CIO:
  National Institute for Occupational Safety and Health (NIOSH)
• Division:
  EID - Education and Information Division
• Topic:
  Workplace Safety & Health
• Location:
  North America
• Pages in Document:
  276-284
• NIOSHTIC Number:
  nn:20044141
• Citation:
  Neurotoxicology 2014 Dec; 45:276-284
• Email:
  rhp9@cdc.gov
• CAS Registry Number:
  Manganese (CAS RN 7439-96-5)
• Federal Fiscal Year:
  2015
• NORA Priority Area:
  Construction ; Manufacturing
• Peer Reviewed:
  True
• Source Full Name:
  Neurotoxicology
• Collection(s):
  National Institute for Occupational Safety and Health
• Main Document Checksum:
  urn:sha-512:dbb99261d85a3e235c049b7fe943ed942befac470be1d82ab41d12567314161d4e3328a35da985ae144dbf94aeba8bc4876444161dcec6c7cedb9901a8b381e4
• Download URL:
  https://stacks.cdc.gov/view/cdc/199960/cdc_199960_DS1.pdf
• File Type:
  [PDF - 358.29 KB ]