NTP meldet DNA-Schäden: stressige Störgeräusche (Allgemein)

Wellenreiter, Montag, 28.10.2019, 22:15 (vor 1659 Tagen) @ H. Lamarr

Die Forscher gingen sogar soweit, SAR-induzierte Geräusche mit einem Tongenerator zu übertönen. Dies ist ebenfalls bei den Kontrolltieren geschehen.

Bitte Link zur Quelle angeben. In der wissenschaftlichen Anhörung zur NTP-Studie vom 26. bis 28. März 2018 (Peer-Review-Report) konnte ich dazu nur folgendes finden:

Dr. Lin asked about the presence of mechanical noise, particularly as related to stirrers or paddles. He asked if the stirrers were turned on in the control chambers. Dr. Wyde confirmed the stirrers were turned on in the control chambers.
[...]
Dr. Cline asked Dr. Capstick to elaborate on the ambient noise within the rats’ hearing range. Dr. Capstick said that the GSM noise was measured, and no components were above 14 kHz. He said that high-frequency noise emanating from the air conditioning equipment was not measured. Efforts were made to keep the stirrers well lubricated to minimize potential noise.
[...]
Dr. Lin asked about the GSM noise [was soll das sein, meint er das GSM-Signal?; Anm. Postingautor], and how it was transmitted into the chambers. Dr. Capstick replied the GSM noise was generated inside the chamber, but its origin was unclear, and efforts to dampen it were unsuccessful. Dr. Lin wondered if the noise was instead introduced from the electronics and power-transfer systems.
[...]
Dr. Cline asked if he was correct that no measurements were taken in the control chambers. Mr. Ladbury confirmed that no measurements were made in the control chambers. Dr. Capstick noted field probes were placed inside the control chambers and noise levels of the measurement system were recorded throughout the study.
[...]
He [Dr. Lin; Anm. Postingautor] raised concerns about the sonic noise in the chambers. Ear or tympanic temperature should have been measured periodically throughout the study to monitor core temperature. Seeing the SAR-dependent reports of schwannomas in rats is perplexing. The experiments specified whole-body exposure, and wbSAR was the key metric for exposure, but a correlation study of pSAR or oSAR with total observed primary tumors should be included in the report.
[...]
He [Dr. Harkema; Anm. Postingautor] requested more details about noise levels and measurements [...]
[...]
Dr. Wyde said he would follow Dr. Harkema’s recommendation regarding the historical controls. Regarding the noise, lighting, and activity issues, more information will be added to the report as suggested, as will more discussion of the equivocal findings and why they did not rise to a higher level. In terms of comparison between the rats and mice, Dr. Wyde said he envisioned a follow-up manuscript on that topic.
[...]
He [Dr. Cline; Anm. Postingautor] requested clarification on the nature of the noise within the testing apparatus and how audible it was to the rats, including whether it was in the rat vocalization range, where it could be a source of stress.
[...]
Dr. Wyde acknowledged that the noise was in the range of rat vocalization, but the correlation between noise and stress is only speculation at this point. He said that the noise was accounted for by piping the same sound into the low-dose chambers so that everything was normalized across the study.
[...]
Dr. Eaton asked Dr. Wyde to clarify his statement that the high-dose noise had been piped into the other chambers, and whether that included the controls, which Dr. Wyde confirmed. Dr. Lin asked how the piping had been done. Dr. Capstick explained the process, which involved placing speakers in the air vents.
[...]
Dr. Lin noted that, for a true control, all aspects of the environment should be the same except for the agent involved. He questioned whether that was the case in the rat studies, particularly with respect to the noise exposure for the sham controls. The lighting also differed from those in the historical controls. Thus, the environmental conditions were not the same.

Offensichtlich war die mechanische Geräuschentwicklung in den Kammern ein mehrfach angesprochenes Thema bei der Anhörung. Der Lärm der Rührer könnte möglicherweise ungesunden Stress bei den Versuchstieren bewirkt haben. Nicht nachvollziehen kann ich die Lösung des NTP, den Lärm nicht etwa zu verhindern, sondern in den Kammern, in denen der Krach weniger laut war (Niedrigdosiskammern), durch Einspeisung von zusätzlichem Lärm via Lautsprecher auf das Niveau der Hochdosiskammern zu bringen. Ob die Kammer mit der unbestrahlten Kontrollgruppe ebenso künstlich belärmt wurde, geht aus dem Protokoll nicht zweifelsfrei hervor, die Rührer waren dort jedenfalls auch in Betrieb.

Was verstehen Sie eigentlich unter "SAR-induzierten Geräuschen"? Sind das mechanische Geräusche der Rührer/Lüfter, die in den Expositionskammern zu hören waren (wahrscheinlich, aber was hat das mit der SAR zu tun?) oder sind das Geräusche, die infolge starker Befeldung mutmaßlich im Hörsystem der Tiere entstanden (unwahrscheinlich, die Tiere können ja nicht über Tinnitus klagen).

Bezüglich der SAR-induzierten Geräusche lässt sich im finalen NTP Dokument TR595 (Quelle: https://ntp.niehs.nih.gov/ntp/htdocs/lt_rpts/tr595_508.pdf) auf Seite 38 folgendes nachlesen:
"Differences in noise levels in the exposure chambers resulting from the heating, ventilation, and air conditioning system were equalized by the installation of sound baffles in various ducts within the system. An audible signal generated by the high intensity GSM signal was detected and equalized in all chambers by the introduction of a “pink noise” masking sound; this masking noise equalized sound levels in all chambers. As a result of the combination of these efforts, noise levels in all chambers were essentially equivalent at approximately 62 dBA, and met the NC-35 noise specification. The noise criterion (NC) is a widely accepted numerical index commonly used to define the maximum allowable noise. It primarily applies to the noise produced by ventilation systems, but is applied to other noise sources, as well. Standards organizations, such as the American National Standards Institute (ANSI), Acoustical Society of America (ASA), and International Standards Organization, provide definitions of various NCs for ambient noise in enclosed spaces. The ANSI/ASA standard (S12.2-2008) recommends NCs for various types of rooms, including private residences (NC 25-40), schools (NC 25-35), offices (NC 25-40), libraries (NC 30-35), and restaurants (NC 40-45). For further discussion of noise control in these studies see the video8 (day 1 a.m. at 2 hours, 0 minutes) (NTP, 2018a). "

Damit ist klar, dass auch die Kontrollen mit einem Maskierungsgeräusch beschallt worden sind. PINK NOISE hat seinen Frequenzschwerpunkt übrigens bei niedrigeren Frequenzen (auch wenn der Mensch hier alle Frequenzen gleich laut empfindet). Da über 14 kHz kein Störsignal festgestellt worden ist, sollten die Tiere auch keine Probleme mit Ultraschallexposition bekommen haben. Dass das Geräusch nur bei GSM auftrat spricht dafür, dass es sich um durch die Pulsung im Zeitschlitzverfahren hervorgerufene Vibrationen in der Expositionsanlage handelt. Mikrowellenhören in den Tieren ist damit nicht gemeint, da das Signal "detektiert" wurde. Leider ist nirgends ein Ton-Spektrum veröffentlicht worden.

Tags:
NTP-Studie, Ultraschall