Date of Award:
5-1-1998
Document Type:
Dissertation
Degree Name:
Doctor of Philosophy (PhD)
Department:
Biology
Committee Chair(s)
David B. Drown
Committee
David B. Drown
Committee
Roger A. Coulombe
Committee
William Popendorf
Committee
Dale R. Gardner
Committee
Howard M. Deer
Committee
Edmund D. Brodie Jr.
Abstract
Exposure to rosin and its resin acid constituents is associated with dermal and pulmonary sensitization. Methodologies to detect resin acid compounds in aerosol from heated rosin flux included air filtration, filter extraction, and gas chromatography/mass spectrometry. Various resin acids were seen in aerosol collected under field conditions, and in the laboratory. The predominant resin acid recovered was dehydroabietic acid, with lower levels of abietic acid and oxidized resin acids, which included 7-oxodehydroabietic, 15-hydroxydehydroabietic, and 7-hydroxydehydroabietic acids. Mass balance experiments with a soldering iron and liquid rosin flux showed most of the nonvolatile mass in unheated flux to be filtrable following heating, confirming production of aerosol contaminant. Abietic acid was unstable on sampling filters held for weeks, while dehydroabietic acid and total solvent-soluble material did not degrade. Scanning electron microscopy showed that laboratory-generated aerosol from liquid flux applied to a soldering iron was respirable in size. Compared to unheated material, dehydroabietic acid was observed in higher proportions relative to abietic acid in aerosol produced by heating rosin core solder in the laboratory. No corresponding change was observed when the rosin core was extracted and heated in the absence of lead/tin solder. Oxidized resin acids are generally regarded as sensitizing rosin compounds in allergic contact dermatitis. A known dermal sensitizer such as 7-oxodehydroabietic acid in rosin-flux derived aerosol supports a hypothesis that resin acid compounds are pulmonary sensitizers. Protein conjugation (haptenation) is necessary to produce an immune response to resin acids in mice. A stable Schiff base linkage between C-7 of 7-oxodehydroabietic acid and a free amino group of L-lysine was predicted, and evidence of conjugation between 7-oxodehydroabietic acid and lysine was provided by fast atom bombardment mass spectrometry. Conjugation of 7-oxodehydroabietic acid with proteins resulting from a similar mechanism may be involved in both allergic contact dermatitis and asthma observed from dermal exposure to, and inhalation of, resin acid compounds, respectively. Ancillary work showed 15-hydroxydehydroabietic acid as a principal metabolite of dehydroabietic acid by an in vitro rat liver enzyme system.
Recommended Citation
Smith, Philip A., "Sensitizing Resin Acids in Aerosol Derived From Rosin Flux Used in Electronics Soldering: Molecular Mechanistic Studies in Resin Acid/Protein Hapten Formation" (1998). Biology. 655.
https://digitalcommons.usu.edu/etd_biology/655
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