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O47-5 Association of metrics of peak exposure with beryllium sensitisation
  1. Mohammed Abbas Virji1,
  2. Christine Schuler1,
  3. Marcia Stanton1,
  4. Michael Kent2,
  5. Alexandr Stefaniak1
  1. 1NIOSH, Morgantown, USA
  2. 2Materion Brush Inc., Elmore, USA

Abstract

Interday or intraday high-intensity exposures (i.e., exposure peaks) may be more relevant for initiating beryllium sensitisation (BeS); such exposures may exceed a threshold necessary to activate the immune response. This study evaluated the relationships of exposure metrics reflecting normal process variation and upset conditions with the prevalence of BeS.

In a study of workers employed from 1994–1999 at a primary beryllium manufacturing facility, exposure metrics were developed using personal full-shift measurement, 15 minutes to 24 hour process-specific area measurements, and process-upset information gleaned from historical reports. Quantitative intensity metrics included highest-ever job-specific average, maximum, 95th percentile, upper tolerance limit (UTL), exceedance fractions (>0.2 and >2 µg/m3), and the product of the geometric mean and geometric standard deviation (GMxGSD). Qualitative metrics included professional judgment of process-upsets (PJPU), and number of process-upset events (e.g., power outage). Relationships among these metrics were evaluated using Spearman correlation and their association with BeS was evaluated using logistic regression with splined and log-transformed exposures.

As anticipated, a high degree of correlation existed among metrics within full-shift measurements (rS: 0.57–0.99) and task/process measurements (rS: 0.56–0.96), and moderate correlation across the two measurement types (rS: 0.48–0.79). Most of these metrics were associated with BeS in logistic models of log-transformed exposures. In splined models, non-linear associations were observed with average, 95th percentile, UTL, and exceedance fraction > 2 µg/m3 from the personal samples. Strong associations with BeS were observed for GMxGSD (OR = 1.8 and 3.6) and PJPU (OR = 8.3 and 8.5) for medium and high categories compared to low category.

Professional judgments regarding process-upset potential and the combined GMxGSD were valuable in predicting BeS; each may reflect a different aspect of interday and intraday exposure peaks. Non-linear associations were possibly due to confounding by chemical form and/or skin exposure, use of respiratory protection, presence of a threshold and/or by genetic susceptibility.

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