Effects of Exposure to Microwaves: Problems and Perspectives

Michaelson, Sol M.

doi:10.1289/ehp.748133

Cited by 27 publications

(10 citation statements)

References 57 publications

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“…The most important sources of microwave radiation that humans may encounter are various industrial microwave generators used for communications, that speed up chemical reactions or are used for heating (896 or 915 MHz); cellular phones (824-850, 900, 1800 or 1900 MHz); cordless phones (from 46 to 5800 MHz); microwave ovens (915 and 2450 MHz); certain diathermy applicators (915 and 2450 MHz); UHF radios (from 470 to 890 MHz); dish antennas (from 0.8 to 15 GHz); and traffic radar (10.5 and 24 GHz). The energy of microwaves is relatively low: one quantum has approximately 10 -5 electron volts (eV), which is considerably lower than the quantum energy needed for the ejection of an electron from a molecule or the breaking of an intra-molecular bond (> 10 eV) [3]; therefore, microwave radiation is considered non-ionizing radiation.…”

Section: Microwavesmentioning

confidence: 99%

“…When irradiating living organisms, microwaves produce two types of effects: thermal and non-thermal. Thermal effects are the consequence of absorption of microwave energy by cell molecules, causing them vibrate much faster and producing general heating of the cell [3]. The extent of microwave absorption within a cell depends on its dielectric constant and electrical conductivity [3].…”

Section: Mechanism Of Microwaves Action On Living Organismsmentioning

confidence: 99%

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The effects of microwave radiation on microbial cultures

Janković¹,

Milosev²,

Novaković³

2014

Hosp Pharm Int Multi J

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Microwaves are non-ionizing electromagnetic waves with frequencies between 0.3 and 300 GHz. Both humans and microorganisms living on the human body are exposed to significant doses of microwave radiation in everyday life. Whether and how microwave radiation could influence the viability and growth of microorganisms is the subject of this educational paper. Studies on the effects of microwaves on the growth of microbial cultures were searched for in biomedical journals indexed in MEDLINE from 1966 to 2012. The published studies showed that microwaves produce significant effects on the growth of microbial cultures, which vary from the killing of microorganisms to enhancement of their growth. The nature and extent of the effect depend on the frequency of microwaves and the total energy absorbed by the microorganisms. Low energy, low frequency microwaves enhance the growth of microorganisms, whereas high energy, high frequency microwaves destroy the microorganisms. However, neither the effects of a wide spectrum of frequencies nor the effects of a wide range of absorbed energies have been investigated. Considering the potentially deleterious influence of microwaves on the symbiotic balance between microorganisms and the human host, further research on the effects of the complete frequency and energy spectra of microwave radiation on the growth of microorganisms is necessary.

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Section: Microwavesmentioning

confidence: 99%

Section: Mechanism Of Microwaves Action On Living Organismsmentioning

confidence: 99%

The effects of microwave radiation on microbial cultures

Janković¹,

Milosev²,

Novaković³

2014

Hosp Pharm Int Multi J

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“…For both E. coli and S. cerevisiae , the microwaving performance for 15 s was sufficient to reduce the number of cells count to nearly 10% of control untreated samples, indicating severe inactivation effect on both microorganisms. Thermal effect is responsible for absorption of microwave energy by cell molecules, producing general heating of the cell 23 . This causes disarrangement of cell membrane and disruption of cell wall structures by destroying the lipopolysaccharides and peptidoglycan of the cell surface.…”

Section: Resultsmentioning

confidence: 99%

Anticipating xenogenic pollution at the source: Impact of sterilizations on DNA release from microbial cultures

Franco

Lin

Loosdrecht

et al. 2019

Preprint

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18The dissemination of DNA and xenogenic elements across waterways is under scientific and public 19 spotlight due to new gene-editing tools, such as do-it-yourself (DIY) CRISPR-Cas kits. Over decades, 20 prevention of spread of genetically modified organisms (GMOs), antimicrobial resistances (AMR), and 21 pathogens from transgenic systems has focused on microbial inactivation. However, sterilization 22 methods have not been assessed for DNA release and integrity. Here, we investigated the fate of 23 intracellular DNA from cultures of model prokaryotic (Escherichia coli) and eukaryotic (Saccharomyces24 cerevisiae) cells, commonly used as microbial hosts for genetic modifications, such as in white 25 biotechnology. DNA release was tracked during exposure of these cultures to conventional 26 sterilization methods. Autoclaving, disinfection with glutaraldehyde, and microwaving are used to 27 inactivate broths, healthcare equipment, and GMOs produced at kitchen table. The results show that 28 current sterilization methods are effective on microorganism inactivation but do not safeguard an 29 aqueous residue exempt of biologically reusable xenogenic material, being regular autoclaving the 30 most severe DNA-affecting method. Reappraisal of sterilization methods is required along with risk 31 assessment on the emission of DNA fragments in urban systems and nature. 32 33 34 35 3 Graphical abstract 36 37 (created with BioRender) 38 39 45 (ARGs) or pathogenicity, and their transport across urban waterways through wastewater treatment 46 plants into nature 2,3 . Novel CRISPR-Cas technologies propel the engineering of microorganisms out of 47 industry boundary with do-it-yourself (DIY) kits available at kitchen table. Uncontrolled, diffuse 48 emission of GMO materials via domestic waste streams could be a threat.49 Current sterilization methods are proven to efficiently inactivate microorganisms. However, a key 50 knowledge gap remains on their impact on DNA and its potential release into industrial, clinical, and 51 domestic sewage. Common methods used to treat industrial broths, healthcare equipment and 52 surfaces, and domestic waste primarily involve autoclaving, glutaraldehyde, and microwaving, 53 respectively. 54Several studies have shown how DNA present in food products react with different sterilization 55 procedures 4-6 . Treatments such as irradiation and autoclaving affect DNA in meat products or edible 56 seeds by decreasing the total DNA content as well as causing DNA fragmentation, degradation and 57 denaturation 7,8 . However, the impact highly depends on the cell type, the sterilization method, and 58 the process conditions. 59Temperature, pressure, pH, and sterilization times significantly exert effects on DNA quality. For 60 instance, temperatures over 100 °C have resulted in significant DNA strand clipping and irreversible 61 loss of secondary structure 4 . Normal autoclaving (121°C between 5 to 20 min) of food and crops did 62 not impeded it to be available for PCR amplification 4,5,9 63Microwaving is co...

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“…For both E. coli and S. cerevisiae, the microwaving performance for 15 s was sufficient to reduce the number of cells to nearly 10% of control untreated samples, indicating severe inactivation effect on both microorganisms. Thermal effect is responsible for absorption of microwave energy by cell molecules, producing general heating of the cell (Michaelson, 1974). This causes disarrangement of cell membrane and disruption of cell wall structures by destroying the lipopolysaccharides and peptidoglycan of the cell surface.…”

Section: Sterilization Methods Inactivated Over 99% Of Living Bacterimentioning

confidence: 99%

Anticipating Xenogenic Pollution at the Source: Impact of Sterilizations on DNA Release From Microbial Cultures

Calderón-Franco

Lin

Loosdrecht

et al. 2020

Front. Bioeng. Biotechnol.

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The dissemination of DNA and xenogenic elements across waterways is under scientific and public spotlight due to new gene-editing tools, such as do-it-yourself (DIY) CRISPR-Cas kits deployable at kitchen table. Over decades, prevention of spread of genetically modified organisms (GMOs), antimicrobial resistances (AMR), and pathogens from transgenic systems has focused on microbial inactivation. However, sterilization methods have not been assessed for DNA release and integrity. Here, we investigated the fate of intracellular DNA from cultures of model prokaryotic (Escherichia coli) and eukaryotic (Saccharomyces cerevisiae) cells that are traditionally used as microbial chassis for genetic modifications. DNA release was tracked during exposure of these cultures to conventional sterilization methods. Autoclaving, disinfection with glutaraldehyde, and microwaving are used to inactivate broths, healthcare equipment, and GMOs produced at kitchen table. DNA fragmentation and PCR-ability were measured on top of cell viability and morphology. Impact of these methods on DNA integrity was verified on a template of free λ DNA. Intense regular autoclaving (121 • C, 20 min) resulted in the most severe DNA degradation and lowest household gene amplification capacity: 1.28 ± 0.11, 2.08 ± 0.03, and 4.96 ± 0.28 logs differences to the non-treated controls were measured from E. coli, S. cerevisiae, and λ DNA, respectively. Microwaving exerted strong DNA fragmentation after 100 s of exposure when free λ DNA was in solution (3.23 ± 0.06 logs difference) but a minor effect was observed when DNA was released from E. coli and S. cerevisiae (0.24 ± 0.14 and 1.32 ± 0.02 logs differences with the control, respectively). Glutaraldehyde prevented DNA leakage by preserving cell structures, while DNA integrity was not altered. The results show that current sterilization methods are effective on microorganism inactivation but do not safeguard an aqueous residue exempt of biologically reusable xenogenic material, being regular autoclaving the most severe DNA-affecting method. Reappraisal of sterilization methods is required along with risk assessment on the emission of DNA fragments in urban systems and nature.

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Effects of Exposure to Microwaves: Problems and Perspectives

Cited by 27 publications

References 57 publications

The effects of microwave radiation on microbial cultures

The effects of microwave radiation on microbial cultures

Anticipating xenogenic pollution at the source: Impact of sterilizations on DNA release from microbial cultures

Anticipating Xenogenic Pollution at the Source: Impact of Sterilizations on DNA Release From Microbial Cultures

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