Student Research: Danielle M. Parette

Particle Size Distribution and Bioavailability of Hexavalent Chromium Exposure in Various Industries


Chromium (Cr) exists in different stable valences in nature, as Cr (-II through VI). In industrial settings, workers are most often exposed to chromium in the metallic chromium (Cr [O]), trivalent (Cr [III]) and hexavalent (Cr [VI]) form. Metallic chromium, with its highest melting point, is used to make steel and other alloys. Trivalent chromium is present in nature in the form of rocks, soil, plants, and volcanic ash, and is incorporated in brick lining for many industrial furnaces due to the high melting temperature, as well as being used to create metals, alloys, and chemical compounds. Hexavalent chromium is produced when Cr (III) is heated in the presence of other mineral bases and atmospheric oxygen.

Cr (VI), which is highly prevalent in industrial settings, has drawn the most attention for potential negative health effects. Cr (VI) is rapidly reduced to Cr (III) once it is in the body, so it is often thought of as being equivalent to exposure of Cr (III). According to Anderson (1993), Cr (III) is not toxic and is considered an essential nutrient. However, in the presence of concentrations that exceed the body’s ability to reduce Cr (VI) to Cr (III), Cr (VI) can produce localized toxic effects including carcinogenicity and tissue damage during the reduction process. While many occupational studies have focused on stainless steel welding, different processes and operations produce exposures to Cr (VI). This study will investigate the differences of Cr (VI) exposures and biological uptake in different industries and processes.

Cr (VI) is also present in tobacco smoke (approximately 1.2%). For this reason, smoking habits of study subjects will be documented and analyzed to determine if smoking is a confounder in the analysis.

Taken from the beginning of thesis