Application of probabilistic methods to address variability and uncertainty in estimating risks for non-cancer health effects

Table 2 Participants, exposure levels, and WMS-VR subtest performance in dry cleaning workers with varying PCE exposure^1,2

	Low Exposure	Medium Exposure	High Exposure
Number of Participants	24	18	23
8-hour Time-Weighted Average PCE Concentration	11.2 ppm	23.2 ppm	40.8 ppm
Adjusted continuous PCE exposure relative to low exposure group^a	NA	4.3 ppm	10.7 ppm
Mean (and 95% UCL) Reduction in WMS-VR score versus mean score in low exposure group ^b	NA	6% (11%)	14% (19%)

^aPCE concentration in medium and high exposure groups minus low dose exposure group were multiplied by (5/7 days * 10/20 m³/day) to adjust from occupational to continuous exposure per EPA, 2012.
^bPercent change in mean WMS-VR score with respect to low exposure group
PCE= perchloroethylene; ppm = parts per million; WMS-VR = Wechsler Memory Scale Visual Reproductions Subtest
¹Echeverria et al., 1995
²EPA, 2012

ISSN: 1476-069X