Details:

Alternative Title:
Neurotoxicology
Personal Author:
Park, Robert M. ; Bouchard, Maryse F. ; Baldwin, Mary ; Bowler, Rosemarie ; Mergler, Donna
Park, Robert M. ; Bouchard, Maryse F. ; Baldwin, Mary ; Bowler, Rosemarie ; Mergler, Donna Less -
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 (< 0.2mg/m(3)).
Subjects:
[+]
Adult Air Pollutants, Occupational Article Burden Fume Half-life Homeostasis Humans Iron Manganese Manganese Poisoning Middle Aged Neuropsychological Tests Occupational Exposure Particulate Matter Time Factors
Source:
Neurotoxicology. 45:276-284.
Pubmed ID:
24721790
Pubmed Central ID:
PMC4552041
Document Type:
Journal Article
Funding:
CC999999/Intramural CDC HHS/United States
Collection(s):
CDC Public Access
Main Document Checksum:
[+]
urn:sha256:65365a6f83049a60baab60a06d0d15efe1f71e76ee79ee9bdd23dfd703c9e34b
Download URL:
https://stacks.cdc.gov/view/cdc/33917/cdc_33917_DS1.pdf
File Type:

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