Publications by authors named "Barbara J Dawson"

A new low global warming refrigerant, 2,3,3,3-tetrafluoro propene, or HFO-1234yf, has been successfully evaluated for automotive air conditioning, and is also being evaluated for stationary refrigeration and air conditioning systems. Due to the advantageous environmental properties of HFO-1234yf versus HFC-134a, coupled with its similar physical properties and system performance, HFO-1234yf is also being evaluated to replace HFC-134a in refrigeration applications where neat HFC-134a is currently used. This study reports on the development and validation of a sampling and analytical method for the determination of HFO-1234yf in air.

View Article and Find Full Text PDF

This paper integrates perspectives from analytical chemistry, environmental engineering, and industrial hygiene to better understand how workers may be exposed to perfluorinated carboxylic acids when handling them in the workplace in order to identify appropriate exposure controls. Due to the dramatic difference in physical properties of the protonated acid form and the anionic form, this family of chemicals provides unique industrial hygiene challenges. Workplace monitoring, experimental data, and modeling results were used to ascertain the most probable workplace exposure sources and transport mechanisms for perfluorooctanoic acid (PFOA) and its ammonium salt (APFO).

View Article and Find Full Text PDF

Ammonium perfluorooctanoate (APFO) exposures were estimated for use in an occupational mortality study using detailed work histories of cohort members and an exposure reconstruction model developed from occupational information and serum PFO(-) data collected in 2004 as part of a cross-sectional health survey. Measured serum PFO(-) levels of the health survey participants were linked with the job title held by the individuals at the time of sampling. The median, range, and distribution of serum levels were calculated to determine the typical exposure intensity for each job title.

View Article and Find Full Text PDF

Perfluorooctanoate (PFO) is the anion of perfluorooctanoic acid. As the ammonium salt, PFO has been used for 50 years as a processing aid in the commercial production of perfluorinated and highly fluorinated polymers. To assess the effectiveness of industrial hygiene controls in processes involving PFO products and intermediates, a wipe test was developed and validated to determine quantitatively the PFO concentration on six surfaces: stainless steel, polycarbonate, Formica, butyl acid suit material, laminated disposable suit material, and a painted surface.

View Article and Find Full Text PDF

Perfluorooctanoic acid is a completely fluorinated carboxylic acid that is usually used in the ammonium salt form as a processing aid in the production of many fluoropolymers and fluoroelastomers. Ammonium perfluorooctanoate readily dissociates in water to give the ammonium and perfluorooctanoate ions. Perfluorooctanoate has been reported to be present in low levels in human serum in the United States and Europe.

View Article and Find Full Text PDF