Assessment of cancer risks due to environmental exposure to asbestos\ud

In a rural area widespread pollution of friable and non-friable waste products was present, used to harden dirt tracks, yards, and driveways during 1935–1974. Exposure to environmental asbestos was assessed by a site approach, based on number of polluted sites within postal code areas, and by a household approach, based on number of households in the close vicinity to polluted sites within postal code areas. Based on asbestos soil investigations, 293 sites were identified with asbestos waste material at the surface, of which 77% contained crocidolite fibres as well as chrysotile fibres. The 293 sites-at-risk varied from 5 m2 to 2722 m2 and were surrounded by 347 households within 100 m of these sites. Distance to the plant was associated with the number of sites (r=0.36), and with the number of households (r=0.52). However, categorization of postal code areas into low, intermediate or high likelihood of exposure to asbestos showed a modest agreement between the site and household approach. In the site approach a total of 2.3 million person-years at risk were estimated with an average exposure of 1674 fibres/m3 and an expected 1.8 cases of malignant mesothelioma each year. The household approach resulted in estimates of 1.2 million person-years at risk, and 0.9 cases of malignant mesothelioma per year, respectively. This study illustrates that asbestos waste on the surface of roads and yards in an area with over 130,000 inhabitants may result in long-term exposure to asbestos that will cause several cases of malignant mesothelioma each year. Although distance to plant, number of polluted sites and number of exposed household were associated, the modest agreement among these measures of exposure indicate that the exposure assessment strategy chosen in a particular study may result in considerable misclassification. Without detailed information on individual behaviour within the polluted area, it is difficult to show that a more individually oriented approach will perform better than an ecological approac

Accelerometry based assessment of gait parameters in children

The objective of this study was to examine if spatio-temporal gait parameters in healthy children can be determined from accelerations measured at the lower trunk as has been demonstrated in adults, previously. Twenty children aged 3-16 years, participated in a protocol that involved repeated walks of different distances in an indoor environment. During walking, accelerations were measured by three orthogonally mounted acceleration sensors in a small wireless device (DynaPort MiniMod) that was attached to the lower back. Based on an inverted pendulum approach, spatio-temporal gait parameters and walking distances were computed from the acceleration signals. Results were compared to video observations and known walking distances and durations. Steps were successfully detected in 99.6+/-0.6% of all observed steps (n=5554). On average, walking distance was accurately estimated (100.6+/-3.3%, range 93-106.7%). No correlation was found between the number of miscounted steps and the total number of steps or the age of the subject. It can be concluded that the use of an inverted pendulum model provides the possibility to estimate spatio-temporal gait parameters in children as well as in adults. The method allows an inexpensive and comfortable assessment of gait parameters in children, is applicable in controlled, indoor environments and could be tested for applicability under free living conditions