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Identification of Carcinogenic Di-amines in the Indoor Environment from Common Urethane Polymer Products

Nishioka, Marcia G.
http://orcid.org/0000-0001-6571-9313
http://rave.ohiolink.edu/etdc/view?acc_num=osu148344608670484

Abstract Details

2016, Doctor of Philosophy, Ohio State University, Public Health.
This research has led to the discovery of a heretofore unrecognized class of carcinogenic aromatic di-amines in the indoor environment by measurement of them in house dust; these di-amines are specific to urethane polymers that are used in common consumer products and building materials such as mattress foams, carpet underlayment, floor coatings, and faux leather. Using newly-developed sequential extraction methods, combined with gas chromatography/mass spectrometry (GC/MS), the di-amines 2,4-diamino toluene and 4,4’-methylene dianiline (DAT and MDA) were identified in house dust in several molecular forms, i.e., as individual molecules, and in polymeric form in urethane micro-particles. The monomeric di-amines were found to exist as neutral molecules, and as ionic species bound to water-soluble humic/fulvic acids and bound to water-insoluble humins. A newly-developed microwave digestion method, combined with GC/MS analysis, was used to identify the urethane polymer micro-particles on the basis of the di-amines that were released via hydrolysis of the urethane bonds therein. This hydrolysis reaction is similar to the hydrolytic actions of cellular enzymes and macrophages that are known to cause in vivo degradation of urethane polymers used in tissue augmentation and replacement. The similarity of these mechanisms suggests that inhalation and/or ingestion of urethane micro-particles may lead to inadvertent exposure to the di-amines via in vivo hydrolysis reactions that are a normal part of the immune system’s “foreign body” response to particles. The sequential methods for extraction of monomeric di-amines by binding mechanism were relatively straight-forward in that they did not involve costly solid phase extraction (SPE) separations; instead, the developed methods relied on vortex mixing, ion exchange with sodium chloride, partitioning at high pH to exclude humic acids, chelation with magnesium chloride to exclude phospholipids, use of a compound class-specific surrogate recovery standard (SRS) for sample-by-sample information on method performance, and a compound class-specific internal standard to verify the completeness of sample cleanup. Conditions for efficient hydrolysis of known quantities of urethane polymers (sofa foam, shoe sole particles, and flakes of floor coating) were tested using both polymers alone and these polymers in the presence of 0.5 g of dust from which monomeric amines had been previously extracted. Conversion of shoe sole particles to amines was ~90%; conversion of the foam and coating was ~40% for similar quantities and this may have been due to the fact that bulk material was used rather than small particles. Experiments with paired samples of 0.5 g of dust and 0.5 g of dust with one added polymer showed that hydrolysis of the urethane micro-particles in dust was not affected by adding polymers, and the hydrolysis capacity of the system was not exceeded. Repeated digestion of dust showed that the initial digestion released at least 90% of the total that was recovered from two sequential digestions. In 86 house dust samples from a childhood leukemia case-control study that were analyzed here, both DAT and MDA were detected as neutral molecules, as ionic species bonded to water-soluble humics, as ionic species bonded to water-insoluble humins, and as constituents of urethane microparticles (the latter being present in 100% of samples). The concentrations of the polymeric-bound di-amines were 100-1000X greater than the sum of the monomeric forms. Two combustion source-related carcinogenic aromatic amines (ß-naphthyl amine and 4-amino-biphenyl) were measured concurrently in the monomeric fractions with these methods; their detection frequencies were lower, and concentrations were lower by factors of 10-100X, despite similar method detection limits. The maximum measured value of DAT in the polymeric fraction was 285 µg/g, which is equal to ~1.5 mg of polymeric urethane particles per g of dust. For the fraction where DAT was bonded via ionic bond to water-soluble humic/fulvic acids, the OR of disease increased (1.10, 1.57, 2.05) as the definition of the exposed and unexposed populations became more restrictive, suggesting an increase in risk with an increase in DAT concentration. These ORs were not statistically significant, so that these are presented as very tentative results that require analysis of a much larger sample set to confirm or refute these findings. This fraction, though, where amines are dislodged with only a salty pH=8 phosphate buffer is, of course, similar to a cellular matrix. This finding speaks to risk as being tied to bioavailability or the ease with which compounds are transferred from the dust matrix (once inhaled or ingested) to the cellular matrix for activation to an ultimate carcinogen and interaction with DNA.
Michael Bisesi, PhD (Advisor)
228 p.
Public Health
2,4-diaminotoluene; 4,4-methylene dianiline; urethane polymers; micro-particles; house dust; indoor environment

Recommended Citations

Citations

  • Nishioka, M. G. (2016). Identification of Carcinogenic Di-amines in the Indoor Environment from Common Urethane Polymer Products [Doctoral dissertation, Ohio State University]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=osu148344608670484

    APA Style (7th edition)

  • Nishioka, Marcia. Identification of Carcinogenic Di-amines in the Indoor Environment from Common Urethane Polymer Products. 2016. Ohio State University, Doctoral dissertation. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=osu148344608670484.

    MLA Style (8th edition)

  • Nishioka, Marcia. "Identification of Carcinogenic Di-amines in the Indoor Environment from Common Urethane Polymer Products." Doctoral dissertation, Ohio State University, 2016. http://rave.ohiolink.edu/etdc/view?acc_num=osu148344608670484

    Chicago Manual of Style (17th edition)

osu148344608670484
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This open access ETD is published by The Ohio State University and OhioLINK.