Dissolution of Stone Wool Fibers with Phenol-urea-formaldehyde Binder in a Synthetic Lung Fluid

Susanne H.Q. Barly, Denis V. Okhrimenko*, Mette Solvang, Yuanzheng Yue, Susan L.S. Stipp

*Corresponding author for this work

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Abstract

Mineral wool products, composed of stone wool fibers and organic binder, are used in many construction applications. Among all their beneficial properties, the most important requirement is safety for human health, such as when fibers are inhaled. For determining long-term toxicity, biosolubility and biopersistence studies in vitro and in vivo are essential. In vitro fiber dissolution rate, which depends on the medium, fiber composition, and the surface available for dissolution, is a key parameter in determining biopersistence of the material in vivo. We investigated how organic binder (phenol-urea-formaldehyde), which can partially shield fiber surfaces from the solution, influences fiber dissolution kinetics in synthetic lung fluid (modified Gamble's solution) at pH 4.5 and temperature 37 °C, in vitro. Dissolution experiments were made in batch and continuous flow using stone wool fibers with typical insulation product binder amounts (0-6 wt %), applied by the standard industrial process. Dissolution rates were determined from element concentrations in the reacted solution, and changes in fiber surface composition and morphology were monitored. Stone wool fiber dissolution was close to stoichiometric and was similar, whether or not the material contained binder. The high dissolution rate (508 ng of fiber/cm2/h) is explained by Al and Fe complexing agents, that is, citrate and tartrate, in the synthetic lung fluid. The organic binder mainly forms micrometer-sized discrete droplets on the fiber surfaces rather than a homogeneous thick coating. During in vitro tests, fibers with organic binder preferentially dissolved in the areas free of binder, forming cavities, whereas the untreated fibers dissolved homogeneously. Propagation of cavities undermined the binder droplets, leading to complete fiber dissolution. Thus, presence of organic binder on stone wool fibers, produced by the standard industrial process, had no measurable effect on dissolution rate in synthetic lung fluid containing Al and Fe complexing agents.
Original languageEnglish
JournalChemical Research in Toxicology
Volume32
Issue number12
Pages (from-to)2398-2410
Number of pages13
ISSN0893-228X
DOIs
Publication statusPublished - 2019

Cite this

Barly, Susanne H.Q. ; Okhrimenko, Denis V. ; Solvang, Mette ; Yue, Yuanzheng ; Stipp, Susan L.S. / Dissolution of Stone Wool Fibers with Phenol-urea-formaldehyde Binder in a Synthetic Lung Fluid. In: Chemical Research in Toxicology. 2019 ; Vol. 32, No. 12. pp. 2398-2410.
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title = "Dissolution of Stone Wool Fibers with Phenol-urea-formaldehyde Binder in a Synthetic Lung Fluid",
abstract = "Mineral wool products, composed of stone wool fibers and organic binder, are used in many construction applications. Among all their beneficial properties, the most important requirement is safety for human health, such as when fibers are inhaled. For determining long-term toxicity, biosolubility and biopersistence studies in vitro and in vivo are essential. In vitro fiber dissolution rate, which depends on the medium, fiber composition, and the surface available for dissolution, is a key parameter in determining biopersistence of the material in vivo. We investigated how organic binder (phenol-urea-formaldehyde), which can partially shield fiber surfaces from the solution, influences fiber dissolution kinetics in synthetic lung fluid (modified Gamble's solution) at pH 4.5 and temperature 37 °C, in vitro. Dissolution experiments were made in batch and continuous flow using stone wool fibers with typical insulation product binder amounts (0-6 wt {\%}), applied by the standard industrial process. Dissolution rates were determined from element concentrations in the reacted solution, and changes in fiber surface composition and morphology were monitored. Stone wool fiber dissolution was close to stoichiometric and was similar, whether or not the material contained binder. The high dissolution rate (508 ng of fiber/cm2/h) is explained by Al and Fe complexing agents, that is, citrate and tartrate, in the synthetic lung fluid. The organic binder mainly forms micrometer-sized discrete droplets on the fiber surfaces rather than a homogeneous thick coating. During in vitro tests, fibers with organic binder preferentially dissolved in the areas free of binder, forming cavities, whereas the untreated fibers dissolved homogeneously. Propagation of cavities undermined the binder droplets, leading to complete fiber dissolution. Thus, presence of organic binder on stone wool fibers, produced by the standard industrial process, had no measurable effect on dissolution rate in synthetic lung fluid containing Al and Fe complexing agents.",
author = "Barly, {Susanne H.Q.} and Okhrimenko, {Denis V.} and Mette Solvang and Yuanzheng Yue and Stipp, {Susan L.S.}",
year = "2019",
doi = "10.1021/acs.chemrestox.9b00179",
language = "English",
volume = "32",
pages = "2398--2410",
journal = "Chemical Research in Toxicology",
issn = "0893-228X",
publisher = "American Chemical Society",
number = "12",

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Dissolution of Stone Wool Fibers with Phenol-urea-formaldehyde Binder in a Synthetic Lung Fluid. / Barly, Susanne H.Q.; Okhrimenko, Denis V.; Solvang, Mette; Yue, Yuanzheng; Stipp, Susan L.S.

In: Chemical Research in Toxicology, Vol. 32, No. 12, 2019, p. 2398-2410.

Research output: Contribution to journalJournal articleResearchpeer-review

TY - JOUR

T1 - Dissolution of Stone Wool Fibers with Phenol-urea-formaldehyde Binder in a Synthetic Lung Fluid

AU - Barly, Susanne H.Q.

AU - Okhrimenko, Denis V.

AU - Solvang, Mette

AU - Yue, Yuanzheng

AU - Stipp, Susan L.S.

PY - 2019

Y1 - 2019

N2 - Mineral wool products, composed of stone wool fibers and organic binder, are used in many construction applications. Among all their beneficial properties, the most important requirement is safety for human health, such as when fibers are inhaled. For determining long-term toxicity, biosolubility and biopersistence studies in vitro and in vivo are essential. In vitro fiber dissolution rate, which depends on the medium, fiber composition, and the surface available for dissolution, is a key parameter in determining biopersistence of the material in vivo. We investigated how organic binder (phenol-urea-formaldehyde), which can partially shield fiber surfaces from the solution, influences fiber dissolution kinetics in synthetic lung fluid (modified Gamble's solution) at pH 4.5 and temperature 37 °C, in vitro. Dissolution experiments were made in batch and continuous flow using stone wool fibers with typical insulation product binder amounts (0-6 wt %), applied by the standard industrial process. Dissolution rates were determined from element concentrations in the reacted solution, and changes in fiber surface composition and morphology were monitored. Stone wool fiber dissolution was close to stoichiometric and was similar, whether or not the material contained binder. The high dissolution rate (508 ng of fiber/cm2/h) is explained by Al and Fe complexing agents, that is, citrate and tartrate, in the synthetic lung fluid. The organic binder mainly forms micrometer-sized discrete droplets on the fiber surfaces rather than a homogeneous thick coating. During in vitro tests, fibers with organic binder preferentially dissolved in the areas free of binder, forming cavities, whereas the untreated fibers dissolved homogeneously. Propagation of cavities undermined the binder droplets, leading to complete fiber dissolution. Thus, presence of organic binder on stone wool fibers, produced by the standard industrial process, had no measurable effect on dissolution rate in synthetic lung fluid containing Al and Fe complexing agents.

AB - Mineral wool products, composed of stone wool fibers and organic binder, are used in many construction applications. Among all their beneficial properties, the most important requirement is safety for human health, such as when fibers are inhaled. For determining long-term toxicity, biosolubility and biopersistence studies in vitro and in vivo are essential. In vitro fiber dissolution rate, which depends on the medium, fiber composition, and the surface available for dissolution, is a key parameter in determining biopersistence of the material in vivo. We investigated how organic binder (phenol-urea-formaldehyde), which can partially shield fiber surfaces from the solution, influences fiber dissolution kinetics in synthetic lung fluid (modified Gamble's solution) at pH 4.5 and temperature 37 °C, in vitro. Dissolution experiments were made in batch and continuous flow using stone wool fibers with typical insulation product binder amounts (0-6 wt %), applied by the standard industrial process. Dissolution rates were determined from element concentrations in the reacted solution, and changes in fiber surface composition and morphology were monitored. Stone wool fiber dissolution was close to stoichiometric and was similar, whether or not the material contained binder. The high dissolution rate (508 ng of fiber/cm2/h) is explained by Al and Fe complexing agents, that is, citrate and tartrate, in the synthetic lung fluid. The organic binder mainly forms micrometer-sized discrete droplets on the fiber surfaces rather than a homogeneous thick coating. During in vitro tests, fibers with organic binder preferentially dissolved in the areas free of binder, forming cavities, whereas the untreated fibers dissolved homogeneously. Propagation of cavities undermined the binder droplets, leading to complete fiber dissolution. Thus, presence of organic binder on stone wool fibers, produced by the standard industrial process, had no measurable effect on dissolution rate in synthetic lung fluid containing Al and Fe complexing agents.

U2 - 10.1021/acs.chemrestox.9b00179

DO - 10.1021/acs.chemrestox.9b00179

M3 - Journal article

C2 - 31682107

VL - 32

SP - 2398

EP - 2410

JO - Chemical Research in Toxicology

JF - Chemical Research in Toxicology

SN - 0893-228X

IS - 12

ER -