Public Comment on OMB Draft Risk Assessment Bulletin

The OIRA draft Risk Assessment Bulletin has worthy intentions and has stimulated useful review and discussion.; Most previous major documents in the development of the risk assessment field have been cited and used appropriately. In general, the formulation is too broad. The Revision should clarify the place of risk assessment as distinguished from hazard identification and from risk management.The category of "influential risk assessment" is unnecessary and confusing, and should be deleted. A single set of six standards would suffice, without the additional nine special standards for "influential risk assessments". Greater transparency within the EOP is desirable to give this process credibility and meet one of the explicit aims of the Bulletin. Finally, several omissions should be addressed: proactive engagement of stakeholders, public health context, deceptive use of quantitation, exclusion for research agencies, interagency steering committee and symmetry of risk assessment guidance for manufacturers as well as regulatory agencies.

Wall temperature jump in polyatomic gas flows

This article deals with the calculations of the temperature jump at the wall for gas flows in the slip regime. The analytical calculations are based on kinetic boundary conditions developed especially for polyatomic molecules. When compared to an expression previously obtained for unstructured molecules, the polyatomic molecule temperature jump reveals supplementary terms of bulk viscosity type due to the internal mode excitation. These terms may be important in high speed flows or in gas flows displaying significant relative density variation at the wall