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  • Development of a cancer-based chronic inhalation reference value for hexavalent chromium based on a nonlinear-threshold carcinogenic assessment.

Development of a cancer-based chronic inhalation reference value for hexavalent chromium based on a nonlinear-threshold carcinogenic assessment.

Regulatory toxicology and pharmacology : RTP (2012-10-30)
Joseph T Haney, Neeraja Erraguntla, Robert L Sielken, Ciriaco Valdez-Flores
ABSTRACT

The carcinogenicity of hexavalent chromium(CrVI) is of significant interest to regulatory agencies for the protection of public health and to industry. Additionally, the mode of action (MOA) and conditions under which CrVI may induce carcinogenicity (e.g., reductive capacity considerations) have recently been the subject of significant scientific debate. Epidemiological data supported by data relevant to the carcinogenic MOA support considering nonlinear-threshold carcinogenic assessments for comparison to default linear low-dose extrapolation approaches. This study reviews epidemiological studies available in the scientific literature and conducts additional statistical dose-response analyses to identify potential carcinogenic thresholds and points of departure (PODs) in the context of supportive MOA information for a nonlinear-threshold inhalation carcinogenic assessment. Dosimetric adjustments and application of appropriate uncertainty factors (total UF of 30) to the selected cumulative exposure POD results in a cancer-based chronic inhalation reference value (ReV) of 0.24 μgCrVI/m(3). This chronic ReV is 300 times higher than the 1 in 100,000 excess cancer risk air concentration of 8E-04 μg/m(3) based on USEPA's unit risk factor.

MATERIALS
Product Number
Brand
Product Description

Sigma-Aldrich
Chromium, chips, 99.995% trace metals basis
Sigma-Aldrich
Chromium, powder, ≥99% trace metals basis, <45 μm
Sigma-Aldrich
Chromium, powder, 99.5%, −100 mesh
Sigma-Aldrich
Chromium, chips, thickness ~2 mm, 99.5%
Chromium, rod, 10mm, diameter 5.0mm, 99.7+%
Chromium, foil, light tested, 25x25mm, thickness 0.05mm, permanent polyester support, 99.99+%
Chromium, foil, light tested, 25x25mm, thickness 0.075mm, permanent polyester support, 99.99+%
Chromium, foil, not light tested, 100x100mm, thickness 0.0125mm, permanent polyester support, 99.99+%
Chromium, foil, not light tested, 100x100mm, thickness 0.015mm, permanent polyester support, 99.99+%
Chromium, foil, not light tested, 100x100mm, thickness 0.01mm, permanent polyester support, 99.99+%
Chromium, foil, not light tested, 100x100mm, thickness 0.025mm, permanent polyester support, 99.99+%
Chromium, foil, not light tested, 100x100mm, thickness 0.02mm, permanent polyester support, 99.99+%
Chromium, foil, not light tested, 100x100mm, thickness 0.03mm, permanent polyester support, 99.99+%
Chromium, foil, not light tested, 100x100mm, thickness 0.04mm, permanent polyester support, 99.99+%
Chromium, foil, not light tested, 25x25mm, thickness 0.0015mm, permanent polyester support, 99.99+%
Chromium, foil, not light tested, 25x25mm, thickness 0.001mm, permanent polyester support, 99.99+%
Chromium, foil, not light tested, 25x25mm, thickness 0.0025mm, permanent polyester support, 99.99+%
Chromium, foil, not light tested, 25x25mm, thickness 0.002mm, permanent polyester support, 99.99+%
Chromium, foil, not light tested, 25x25mm, thickness 0.003mm, permanent polyester support, 99.99+%
Chromium, foil, not light tested, 25x25mm, thickness 0.004mm, permanent polyester support, 99.99+%
Chromium, foil, not light tested, 25x25mm, thickness 0.005mm, permanent polyester support, 99.99+%
Chromium, foil, not light tested, 25x25mm, thickness 0.007mm, permanent polyester support, 99.99+%
Chromium, foil, not light tested, 25x25mm, thickness 0.009mm, permanent polyester support, 99.99+%
Chromium, foil, not light tested, 25x25mm, thickness 0.0125mm, permanent polyester support, 99.99+%
Chromium, foil, not light tested, 25x25mm, thickness 0.015mm, permanent polyester support, 99.99+%
Chromium, foil, not light tested, 25x25mm, thickness 0.01mm, permanent polyester support, 99.99+%
Chromium, foil, not light tested, 25x25mm, thickness 0.025mm, permanent polyester support, 99.99+%
Chromium, foil, not light tested, 25x25mm, thickness 0.03mm, permanent polyester support, 99.99+%
Chromium, foil, not light tested, 25x25mm, thickness 0.04mm, permanent polyester support, 99.99+%
Chromium, foil, not light tested, 25x25mm, thickness 0.05mm, permanent polyester support, 99.99+%