Characteristics of Dusts Encountered during the Production of Cemented Tungsten Carbides

Stefaniak, Aleksandr B.; Day, Gregory A.; Harvey, Christopher J.; Leonard, Stephen S.; Schwegler‐Berry, Diane; Sahakian, Nancy; Chisholm, William P.

doi:10.2486/indhealth.45.793

Cited by 20 publications

(24 citation statements)

References 19 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…In general, median cobaltand tungsten-containing particle MMAD values were similar within work areas and confirm the potential for co-exposure to chemically heterogeneous respirable-and thoracic-size particles. Additionally, cobalt MMAD values determined using personal impactor samples were similar to those determined previously using stationary impactor samplers at these facilities (Stefaniak et al, 2007). Median MMADs for cobalt differed among the three facilities: 17.4 mm (metal separation), 13.8 mm (powder handling), and 10.8 mm (forming/machining) (Po0.0001 using the Kruskal-Wallis test).…”

Section: Eight-stage Impactor Samplessupporting

confidence: 76%

“…In general, there are many competing factors that would influence within-and between-worker variance components. For example, the production levels and relative fractions of cobalt and tungsten in hard metal formulations vary among batches in a day and/or between days (Stefaniak et al, 2007); therefore, it is difficult to elucidate the potential contribution of different factors to the variance components. Despite our inability to collect additional information on exposure determinants during sampling, which limits our ability to further investigate the causes of exposure variation and their impact on between-or within-worker variances, these data have practical implications for exposure mitigation efforts.…”

Section: Discussionmentioning

confidence: 99%

“…At the company under study, the CTC-manufacturing process spans three facilities all within a 50 km radius of one another (Stefaniak et al, 2007). The manufacturing process begins in the metal separation facility with the reduction of tungsten oxide powder to yield tungsten metal powder.…”

Section: Methodsmentioning

confidence: 99%

“…Additional details of these job activities and dustiness of specific jobs are provided in Appendix A. Based on prior knowledge of work processes, similarities in physicochemical properties of airborne particles and bulk powders within work areas (Stefaniak et al, 2007), and practical limitations associated with field sampling, we categorized exposures by work areas.…”

Section: Methodsmentioning

confidence: 99%

“…The MMADs of cobalt-containing particles tended to be in the thoracic and inhalable range (Tables 6 and 7), though measurable mass concentrations of respirable particle fractions existed in all work areas (Table 4). Previous elemental analysis of aerosols generated among these three facilities revealed that regardless of the work area, all particles contained cobalt, either as discrete cobalt particles or in association (agglomerated/ aggregated) with tungsten (Stefaniak et al, 2007). In vitro tests revealed that cobalt dissolves from both pure cobalt powder and from pre-and post-sintered tungsten carbide powders in artificial lung fluids (Stopford et al, 2003).…”

Section: Occupational Asthmamentioning

confidence: 98%

See 4 more Smart Citations

Characterization of exposures among cemented tungsten carbide workers. Part I: Size-fractionated exposures to airborne cobalt and tungsten particles

Stefaniak

Virji

Day

2008

J Expo Sci Environ Epidemiol

View full text Add to dashboard Cite

As many as 30,000 workers in the United States of America are exposed to cemented tungsten carbides (CTC), alloys composed primarily of tungsten carbide and cobalt, which are used in cutting tools. Inhalation of cobalt-containing particles may be sufficient for the development of occupational asthma, whereas tungsten carbide particles in association with cobalt particles are associated with the development of hard metal disease (HMD) and lung cancer. Historical epidemiology and exposure studies of CTC workers often rely only on measures of total airborne cobalt mass concentration. In this study, we characterized cobalt-and tungsten-containing aerosols generated during the production of CTC with emphasis on (1) aerosol ''total'' mass (n ¼ 252 closed-face 37 mm cassette samples) and particle size-selective mass concentrations (n ¼ 108 eight-stage cascade impactor samples); (2) particle size distributions; and (3) comparison of exposures obtained using personal cassette and impactor samplers. Total cobalt and tungsten exposures were highest in work areas that handled powders (e.g., powder mixing) and lowest in areas that handled finished product (e.g., grinding). Inhalable, thoracic, and respirable cobalt and tungsten exposures were observed in all work areas, indicating potential for co-exposures to particles capable of getting deposited in the upper airways and alveolar region of the lung. Understanding the risk of CTC-induced adverse health effects may require two exposure regimes: one for asthma and the other for HMD and lung cancer. All sizes of cobalt-containing particles that deposit in the lung and airways have potential to cause asthma, thus a thoracic exposure metric is likely biologically appropriate. Cobalt-tungsten mixtures that deposit in the alveolar region of the lung may potentially cause HMD and lung cancer, thus a respirable exposure metric for both metals is likely biologically appropriate. By characterizing size-selective and co-exposures as well as multiple exposure pathways, this series of papers offer an approach for developing biologically meaningful exposure metrics for use in epidemiology.

show abstract

Section: Eight-stage Impactor Samplessupporting

confidence: 76%

Section: Discussionmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Section: Occupational Asthmamentioning

confidence: 98%

See 3 more Smart Citations

Characterization of exposures among cemented tungsten carbide workers. Part I: Size-fractionated exposures to airborne cobalt and tungsten particles

Stefaniak

Virji

Day

2008

J Expo Sci Environ Epidemiol

View full text Add to dashboard Cite

show abstract

Tungsten

Haire¹,

Harbison²

2015

Hamilton &Amp; Hardy's Industrial Toxicology

View full text Add to dashboard Cite

Comparison between exhaled breath condensate analysis as a marker for cobalt and tungsten exposure and biomonitoring in workers of a hard metal alloy processing plant

Broding

Michalke

Göen

et al. 2008

Int Arch Occup Environ Health

View full text Add to dashboard Cite

According to our study, urinary concentrations of Co and W seem to be more reliable indicators of current workplace exposure than EBC concentrations. As far as new methods and exposure matrices for valid concentration measurements in respiratory organs and possible hazardous effects--especially of cobalt--in the lung are concerned, the present results are less clear-cut, and further research is required.

show abstract

Characteristics of Dusts Encountered during the Production of Cemented Tungsten Carbides

Cited by 20 publications

References 19 publications

Characterization of exposures among cemented tungsten carbide workers. Part I: Size-fractionated exposures to airborne cobalt and tungsten particles

Characterization of exposures among cemented tungsten carbide workers. Part I: Size-fractionated exposures to airborne cobalt and tungsten particles

Tungsten

Comparison between exhaled breath condensate analysis as a marker for cobalt and tungsten exposure and biomonitoring in workers of a hard metal alloy processing plant

Contact Info

Product

Resources

About