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Waterpipe smoking among Danish, Swedish, and German youth is increasing dramatically, indicating the emergence of a new health threat. This study assessed the association between waterpipe smoking and progression to regular cigarette smoking among Danish continuation school students during 2004-2005. All participants (N = 762) had smoked cigarettes on a nonregular basis at baseline. Among boys, waterpipe smoking frequency was predictive of being a regular cigarette smoker at follow-up eight months later. Further research should examine waterpipe smoking as a potential predictor of cigarette smoking. The study's limitations are noted.

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Starch is an attractive biofoam candidate as replacement of expanded polystyrene (EPS) in packaging materials. The main technical problems with starch foam include its hygroscopic nature, sensitivity of its mechanical properties to moisture content, and much lower energy absorption than EPS. In the present study, a starch-based biofoam is for the first time able to reach comparable mechanical properties (E = 32 MPa, compressive yield strength, 630 kPa) to EPS at 50% relative humidity and similar relative density. The reason is the nanocomposite concept in the form of a cellulose nanofiber network reinforcing the hygroscopic amylopectin starch matrix in the cell wall. The biofoams are prepared by the freezing/freeze-drying technique and subjected to compressive loading. Cell structure is characterized by FE-SEM of cross sections. Mechanical properties are related to cell structure and cell wall nanocomposite composition. Hierarchically structured biofoams are demonstrated to be interesting materials with potential for strongly improved mechanical properties.