Is exposure to formaldehyde in air causally associated with leukemia?—A hypothesis-based weight-of-evidence analysis

Recent scientific debate has focused on the potential for inhaled formaldehyde to cause lymphohematopoietic cancers, particularly leukemias, in humans. The concern stems from certain epidemiology studies reporting an association, although particulars of endpoints and dosimetry are inconsistent across studies and several other studies show no such effects. Animal studies generally report neither hematotoxicity nor leukemia associated with formaldehyde inhalation, and hematotoxicity studies in humans are inconsistent. Formaldehyde's reactivity has been thought to preclude systemic exposure following inhalation, and its apparent inability to reach and affect the target tissues attacked by known leukemogens has, heretofore, led to skepticism regarding its potential to cause human lymphohematopoietic cancers. Recently, however, potential modes of action for formaldehyde leukemogenesis have been hypothesized, and it has been suggested that formaldehyde be identified as a known human leukemogen. In this article, we apply our hypothesis-based weight-of-evidence (HBWoE) approach to evaluate the large body of evidence regarding formaldehyde and leukemogenesis, attending to how human, animal, and mode-of-action results inform one another. We trace the logic of inference within and across all studies, and articulate how one could account for the suite of available observations under the various proposed hypotheses. Upon comparison of alternative proposals regarding what causal processes may have led to the array of observations as we see them, we conclude that the case fora causal association is weak and strains biological plausibility. Instead, apparent association between formaldehyde inhalation and leukemia in some human studies is better interpreted as due to chance or confounding

Sur l’interprétation du phénomène de relaxation diélectrique : cas de molécules à chaîne hydrocarbonée flexible

Des mesures de permittivité complexe sur quatre bromures d'alkyles en C5 et deux éthers aliphatiques montrent que le profil asymétrique des diagrammes de Cole et Cole s’accentue lorsque la longueur de la chaîne hydrocarbonée augmente. Sur la base de ces résultats expérimentaux, les multiples théories susceptibles d’expliquer cette déformation sont systématiquement discutées; une approche nouvelle de cette question, à partir des équations de viscoélasticité, est aussi envisagée. Force est cependant de reconnaître qu’aucun modèle n'est réellement satisfaisant

Mesures interférométriques précises de la permittivité complexe des liquides dans un large domaine de fréquences

Broad band interferometric techniques, using oversized rectangular waveguides, are suitable for accurate measurements of complex permittivity, in the frequency range 15- 300 GHz. The problems that arise from trapped mode resonance effects, are considered and solved quite properly by designing specific « mode filters » of low cost. Some improvements to get a better resolution of interferograms are also reported. The coherence of our results is proved by agreement with far IR measurements and other ones carried out in the X-band with an equivalent standard waveguide apparatus shortly described. The Cole-Cole plots, at 25 °C and at low temperature (— 60 °C), for some interesting liquids, are reproduced in order to characterize the accuracy of all the techniques used in the present work.Une même technique interférométrique, en guide surdimensionné rectangulaire, peut parfaitement être utilisée pour mesurer la permittivité complexe des liquides, dans une large bande de fréquences allant de 15 à 300 GHz. Les problèmes liés à la résonance de modes parasites sont réexaminés ; ils peuvent être résolus de manière satisfaisante par la réalisation de filtres de modes peu onéreux. Diverses dispositions, d'ordre électronique, permettant d'améliorer le pouvoir de résolution des interférogrammes, sont également rapportées. La cohérence des mesures ressort d'une simple comparaison avec les résultats obtenus en IR lointain et avec ceux que fournit un montage équivalent, réalisé en guide standard, bande X, dont on donne une brève description. Les diagrammes de Cole et Cole, à température ambiante et à basse température (— 60 °C), de quelques liquides intéressants, sont reproduits pour situer les performances des diverses techniques utilisées

Consistency of photon emission intensities for efficiency calibration of gamma-ray spectrometers in the energy range from 20 keV to 80 keV

Proceedings of the 21st International Conference on Radionuclide Metrology and its Applications (ICRM), 15-19 May 2017, Buenos Aires, Argentina. Organizer: Argentinian Comis Nacl Energia AtomicaInternational audienceThe efficiency calibration for different high-purity germanium detectors in the low-energy range was established by the conventional method, using standard radioactive sources. The peak shapes were carefully analysed taking account of natural linewidth, full-energy width at half maximum and scattering. Complementary information was obtained by Monte Carlo simulation using the PENELOPE code, after optimization of the geometrical parameters. This was used to measure photon emission intensities of some low-energy emitting radionuclides, including 133Ba, and compared to the tabulated values

Anaerobic digestion of pig manure

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