Dataset Information

Pentadecafluorooctanoic-acid-free polytetrafluoroethylene and mechanism of PFOA formation by ?-irradiation.

ABSTRACT: Low-molecular-weight (Mw) polytetrafluoroethylene (PTFE) micropowder is added to wax for use in automotive equipment and printing machines and is produced by radiation-initiated degradation under atmospheric conditions. However, pentadecafluorooctanoic acid (PFOA) is produced as a by-product in concentrations greater than 25 ppb, which is problematic because PFOA does not degrade in the environment. Herein, we clarify the PFOA-formation mechanism and develop a manufacturing process for a novel low-Mw PTFE micropowder that does not contain PFOA (less than 5 ppb). The process uses combined irradiation and heat treatment in an oxygen-free atmosphere. Furthermore, PFOA-free PTFE micropowder can be produced on the 10-kg scale.

SUBMITTER: Oshima A

PROVIDER: S-EPMC7435272 | biostudies-literature | 2020 Aug

REPOSITORIES: biostudies-literature

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Pentadecafluorooctanoic-acid-free polytetrafluoroethylene and mechanism of PFOA formation by γ-irradiation.

Oshima Akihiro A Tanaka Takayuki T Nakaya Hideki H Senba Ryosuke R Satoh Kazuyuki K

Scientific reports 20200818 1

Low-molecular-weight (M<sub>w</sub>) polytetrafluoroethylene (PTFE) micropowder is added to wax for use in automotive equipment and printing machines and is produced by radiation-initiated degradation under atmospheric conditions. However, pentadecafluorooctanoic acid (PFOA) is produced as a by-product in concentrations greater than 25 ppb, which is problematic because PFOA does not degrade in the environment. Herein, we clarify the PFOA-formation mechanism and develop a manufacturing process fo ...[more]

PMID: 32811856

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Project description:Perfluorooctanoic acid (PFOA) is a potent hepatocarcinogen and peroxisome proliferator (PP) in rodents. Humans are not susceptible to peroxisome proliferation and are thought to be refractory to carcinogenesis by PFOA and other PPs. However, previous studies with rainbow trout have shown that they are also insensitive to peroxisome proliferation by the PP, dehydroepiandrosterone (DHEA), but are still susceptible to enhanced hepatocarcinogenesis after chronic exposure. In this study, we determined whether PFOA is also a tumor promotor in trout and then examined hepatic gene expression profiles to further investigate possible mechanisms of action. Trout were initiated as fry to the hepatocarcinogen, aflatoxin B1, and then fed 200-1800 ppm PFOA in the diet for 30 weeks. Two structurally diverse PPs, clofibrate (CLOF) and DHEA, were included for comparison. Hepatic gene expression profiles were subsequently examined in animals exposed to similar doses of PFOA, DHEA and CLOF along with 5 ppm 17β-estradiol (E2; a known tumor promotor) in the diet. PFOA (1800 ppm) and DHEA treatments resulted in enhanced liver tumor incidence and multiplicity while CLOF showed no effect. Carcinogenesis seemed independent of peroxisome proliferation as no induction of peroxisomal β-oxidation and catalase activity were observed. Alternately, plasma VTG was elevated in fish fed PFOA and DHEA suggesting that estrogenic mechanisms may play a role. Both tumor promotors, PFOA and DHEA, resulted in strong correlation of transcriptional profiles with E2 by Pearson correlation (R=0.81 and 0.78, respectively). In comparison, CLOF regulated no genes in common with E2. Overall, these data suggest that the tumor promoting activities of DHEA and PFOA in trout are independent of peroxisome proliferation and may involve estrogenic mechanisms. Juvenile trout, 12-18 months old, were fed experimental diets containing 500 or 1800 ppm PFOA, 1800 ppm CLOF, 750 ppm DHEA, 5 ppm E2 or 0.15 % dimethyl sulfoxide vehicle control for 14 days. Liver samples were collected for microarray analysis. Hybridizations were performed using standard reference design with dye-swapping. For each sample, equal amounts of RNA (µg) were pooled from five fish per tank for every treatment (n=3 biological replicates per treatment). cDNA from two of the three biological replicates was dye-swapped and hybridized to two slides as technical replicates (5 arrays per treatment).

Dataset Information

Pentadecafluorooctanoic-acid-free polytetrafluoroethylene and mechanism of PFOA formation by ?-irradiation.

Publications

Pentadecafluorooctanoic-acid-free polytetrafluoroethylene and mechanism of PFOA formation by γ-irradiation.

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