EXTREME SENSITIVITY AND THE PRACTICAL IMPLICATIONS OF RISK ASSESSMENT THRESHOLDS

Traditional risk-assessment theory assumes the existence of a threshold for non-cancer health effects. However, a recent trend in environmental regulation rejects this assumption in favor of non-threshold linearity for these endpoints. This trend is driven largely by two related concepts: (1) a theoretical assumption of wide-ranging human sensitivity, and (2) inability to detect thresholds in epidemiologic models. Wide-ranging sensitivity assumes a subpopulation with extreme background vulnerability, so that even trivial environmental exposures are hazardous to someone somewhere. We use examples from the real world of clinical medicine to show that this theoretical assumption is inconsistent with the biology of mammalian systems and the realities of patient care. Using examples from particulate-matter air-pollution research, we further show that failure to reject linearity is usually driven by statistical rather than biological considerations, and that nonlinear/threshold models often have a similar or better fit than their linear counterparts. This evidence suggests the existence of practical, real-world thresholds for most chemical exposures

A crustal seismic profile across Sicily

A crustal reflection seismic profile, more than 100 km long, was recorded across central Sicily, from the Tyrrhenian shore to the Sicily Channel, to understand the deep structures and the collision mechanisms between Europe and Africa and the subsequent geodynamic evolution. The profile was acquired using explosive sources and 240 active channels recorded by a Sercel 408-XL, 24 bits A/D converter, with a 12 km spread and a 24-fold coverage. The data were processed following a non-conventional procedure in order to preserve the relative amplitudes of the reflections and to better investigate the Sicily deep structures down to the Moho. The main highlighted structures are the dramatic flexure of the Iblean crust, the huge, deeper than expected, trough of Caltanissetta consisting of deep seated thrusts and nappes, and the imbricate thrust system of rigid bodies characterizing the northern Maghrebian chain. We designed an ad hoc acquisition and processing in order to highlight these main geological features in the seismic stacked section. Moreover, the deepest parts of the Caltanissetta trough are imaged for the first time, and its bottom is now fixed at more than 7 s TWT. The giant crustal wedge flexuring the Iblean foreland and the Moho geometries are examinated

Molecular genotyping of bacillus anthracis strains from Georgia and northeastern part of Turkey

Bacillus anthracis is the causal agent of anthrax and has a history of use as a biological weapon. Anthrax cases occur worldwide and the disease is endemic in certain regions. Here we describe a study of the genetic diversity of B. anthracis strains in two endemic areas: The country of Georgia and the Kars region of Turkey. Thirty Turkish isolates and thirty Georgian isolates were subjected to Single Nucleotide Polymorphism (SNP) sub typing, followed by higher-resolution genotyping using 25-loci variable-number tandem repeat analysis (MLVA-25). Canonical SNP typing indicated that Turkish strains belonged to both the A.Br.003 linage and the Australian 94 lineage. In light of a recent analysis that placed the majority of Georgian B. anthracis isolates in one phylogenetic group, we screened the Turkish strains using a previously developed Georgian SNP panel. Minimal diversity was observed among the Kars strains within the Georgian SNP lineage: all 30 of these strains grouped with A.Br.026, ten strains were derived from A.Br.028, and only two isolates belonged to A.Br.029. According to the results of MLVA-25 genotyping, all 30 Turkish strains belong to two clusters. Cluster A is more diverse than cluster B. Our results suggest that B. anthracis strains originating from Georgia and the northeastern part of Turkey are genetically interrelated, which could be explained by the geographic proximity of the countries

Molecular genotyping of bacillus anthracis strains from Georgia and northeastern part of Turkey

Bacillus anthracis is the causal agent of anthrax and has a history of use as a biological weapon. Anthrax cases occur worldwide and the disease is endemic in certain regions. Here we describe a study of the genetic diversity of B. anthracis strains in two endemic areas: The country of Georgia and the Kars region of Turkey. Thirty Turkish isolates and thirty Georgian isolates were subjected to Single Nucleotide Polymorphism (SNP) sub typing, followed by higher-resolution genotyping using 25-loci variable-number tandem repeat analysis (MLVA-25). Canonical SNP typing indicated that Turkish strains belonged to both the A.Br.003 linage and the Australian 94 lineage. In light of a recent analysis that placed the majority of Georgian B. anthracis isolates in one phylogenetic group, we screened the Turkish strains using a previously developed Georgian SNP panel. Minimal diversity was observed among the Kars strains within the Georgian SNP lineage: all 30 of these strains grouped with A.Br.026, ten strains were derived from A.Br.028, and only two isolates belonged to A.Br.029. According to the results of MLVA-25 genotyping, all 30 Turkish strains belong to two clusters. Cluster A is more diverse than cluster B. Our results suggest that B. anthracis strains originating from Georgia and the northeastern part of Turkey are genetically interrelated, which could be explained by the geographic proximity of the countries