Ultraviolett strålning och hälsa : ett kunskapsunderlag

Ultraviolet radiation and health Exposure to ultraviolet radiation can cause adverse effects on skin, eyes, and the immune system. Some effects are acute : they appear after short duration of exposure to ultraviolet radiation. Such effects are erythema, increased pigmentation, photokeratitis and photoconjunctivitis. Other effects such as elastosis and certain forms of skin cancer are regarded as irreversible and appear after chronic exposure. The acute effects and the photoageing of the skin are commonly occurring, while the more serious cancer forms are less common : but their occurrences have increased in recent years. This is considered to be at least partly attributed to an increased exposure to ultraviolet radiation. Thus, there is an obvious need to limit the total exposure to ultraviolet radiation. Internationally, ICNIRP have developed guidelines for the limitation of exposure to ultraviolet radiation. These limitations give individuals with normal sensitivity a protection against acute effects on skin and eyes, and are also thought to protect against some of the long-term effect (e.g. certain cancer forms). Several forms of malignant melanoma are, on the other hand, thought to be a result of single episodes of heavy exposure. High levels of UV radiation can occur within Swedish industry at e.g. welding and UV curing of surface coatings. The possibilities to locally measure and control these levels at a relevant cost have improved during the last decade.Ultraviolett strålning (UV) indelas vanligen i UVA, UVB och UVC. Den dos som ger upphov till en definierad skada kallas tröskeldos. Tröskeldosen plottad som funktion av våglängd benämns aktionsspektrum. Lämplig längsta expositionstid kan beräknas på basis av aktionsspektrum genom att addera de viktade doskomponenterna från varje våglängdsområde i en exponering. UV orsakar skador på lipider och proteiner i cellmembran och inne i cellen samt på DNA. UV har flera olika skadeeffekter på huden som beror på intensitet, exponeringstid och våglängdsområde (UVA eller/och UVB). UV kan skada arvsanlagen i hudens celler samt orsaka hudrodnad, brännskador, elastos (förtjockad och rynkig hy) samt godartade och elakartade former av hudcancer. En liten andel av befolkningen har hud som är abnormt känslig för UV. Hornhinnan blockerar all UV med kortare våglängd än 290 nm. Linsen filtrerar bort merparten av all UV mellan 290-400 nm. En överdos av UV mot ögat ger akut ögonlocksrodnad och svullnad och inflammatorisk reaktion i bindehinna och hornhinna som är reversibel inom 1-2 dygn. Om dosen är mycket hög uppkommer irreversibel grå starr. Långvarig exponering av ögat för UV är associerat till förändringar i bindehinnan, hornhinnan och linsen. Iakttagelser att UV-strålning har en hämmande effekt på immunsystemet har gjorts såväl i djurexperiment som i studier på människor. Solljusexponering reducerade bl a mängden cirkulerande T-lymfocyter och naturliga mördarceller i blodet hos friska kontrollpersoner. De immunhämmande effekterna av UV-strålning kan tänkas ha negativa hälsoeffekter genom att nedsätta motståndskraften för infektioner samt eventuellt främja tumöruppkomst. Det föreligger en individuell variabilitet i känslighet för immunsuppression efter UVB-bestrålning. Den skyddande effekten av solskyddskrämer mot UV-inducerad immunsuppression är fortfarande otillräckligt studerad. Tidigare ansatser att erhålla en bättre kontroll av yrkesmässig exponering för UV-strålning har försvårats av bristen på praktiskt och ekonomiskt försvarbara mätinstrument. Numera finns sådana instrument för mätning av absolutnivåer samt även olika former av billiga och tillförlitliga persondosimetrar vilket kan vara ett alternativ för övervakning av UV-exponering hos utsatta yrkesgrupper. Den i arbetslivet mest frekventa exponeringen för UV-strålning är självfallet utomhusvistelse. Vid inomhusarbete kan dock exponering för väsentligt högre nivåer av UV-strålning uppkomma vid bristande avskärmning av ljuskällan i samband med UV-härdning av akrylatlacker, elektrosvetsning och lasersvetsning. Även lysrör för medicinska UV-behandlingar och ofiltrerade halogenlampor kan medföra höga nivåer

The economics of general thromboembolic prophylaxis

The clinical and economic effects of each of 3 alternatives—no prophylaxis, general prophylaxis, and selective treatment—have been assessed in conjunction with 3 types of surgery—general surgery, the subset surgery for cholelithiasis, and elective hip surgery. The costs of thromboembolic and hemorrhagic complications have been calculated from the figures for 28 patients hospitalized at the Department of Surgery, Malmö General Hospital, Malmö, Sweden. The anticipated number of thromboembolic complications—and thus even the number of fatal pulmonary embolisms—can be minimized in all 3 types of surgery by means of general prophylaxis. General prophylaxis with low-dose heparin is, however, accompanied by the greatest incidence of hemorrhagic complications. Health care costs are minimized with general prophylaxis in elective hip and general surgery, while no prophylaxis is the best alternative in surgery for cholelithiasis. From the patient's point of view, general prophylaxis minimizes the duration of thromboembolic disease in general surgery as well as in elective hip surgery. In surgery for cholelithiasis, however, no differences in health loss for the individual are shown between the 2 main alternatives, no prophylaxis and general prophylaxis. Selective treatment means treatment after diagnosis of thrombosis with some screening method. The alternative selective treatment was the least satisfactory of those 3 studied

Reproductive performance in high-producing dairy cows

Milk yields >10,000 kg/year are common in modern dairy production, owing to improved nutrition, management and genetic gains through use of progeny-tested bulls. However, reproductive performance has decreased worldwide in many cows with a high genetic potential for milk production, particularly in the Holstein breed. Moreover, cow robustness and longevity is also threatened by increasing stress, udder health disturbances and of locomotion disorders. Genetic global misuse of a narrow base of AI sires -including those selected for high milk yield but not consequently for health and reproductive traits- has not only contributed to these undesirable effects on animal health and welfare but, together with sub-optimal management, jeopardized the ethical and economical sustainability of modern dairy farming. This review describes the state-of-the-art of this multifaceted problem and advises on how to ameliorate it, since it is not seen as an unsolvable problem. Use of high-fertility sires, of balanced breeding programs with adequate trait measurements, diet optimization, design of buildings and management systems that best support reproduction as well as cross-breeding; are among short- and medium-term strategies. In a longer perspective, holistic- and trait-orientated research on interrelations between gene regulation of nutrition, lactation and stress is needed; aiming at identifying reliable and cheap markers to be used on-line and on-farm as recorders of genetic traits. Awaiting the full application of juvenile genomic selection, a wider inclusion of functional traits (fertility, health and longevity) and of product quality are mandatory for breeding programs in order to secure acceptable fertility, sustained milk production and the best welfare of dairy cows. Such strategies have proven successful in the Nordic countries and are being increasingly adopted by others

Where does the explosive energy in rock blasting rounds go?

The energy partitioning of limestone production blasts has been measured under well controlled conditions; from rock properties determination, structural mapping and monitoring of drilling and charging, to VOD, 3D accelerometer and bench face movement measurements during the blast to post-blast fragment size measurements. The efficiency of the transfer of energy from the charges to the surrounding rock has been estimated by introducing a new explosives test, the cylinder expansion test, which is discussed to be-gin with. Hereby in-hole losses, seismic energy, kinetic energy of throw and fragmentation energy have been calculated. For the AN doped gassed bulk emulsion used in the quarry, it is estimated that 60-70 % of the explosive energy is transmitted to the rock, that the seismic and kinetic energy terms both amount to roughly 3-12 % and the fragmentation energy to less than 1-2 %. One candidate for the remaining losses, which are larger than the other three terms together, is the crushing of the blast-hole region. A rough estimate for the energy partitioning in bench blasting rounds is finally given.Godkänd; 2004; 20061211 (ysko)</p

Data from: Consequences for piglet performance of group housing lactating sows at one, two, or three weeks post-farrowing

Housing lactating sows with piglets in a multi-suckling pen from around 14 days post-farrowing is common practice in Swedish organic piglet production. However, nursing-suckling interaction is less frequent in multi-suckling pens than in individual farrowing pens, thus affecting piglet performance, e.g., piglet growth. Moreover, piglet mortality is higher in systems using multi-suckling pens. Three management routines whereby lactating sows with piglets were moved from individual farrowing pens to multi-suckling pens at one, two, or three weeks post-farrowing were compared in terms of nursing-suckling interaction and piglet performance. Correlations between nursing-suckling interaction, piglet performance, and piglet mortality were also examined. In total, 43 Yorkshire sows with piglets were included in the study. Nursing-suckling interaction and all piglet performance parameters except piglet mortality did not differ between management routines. Piglet mortality in the individual farrowing pens did not differ between management routines, but piglet mortality in the multi-suckling pen was lower (P<0.05) when piglets were group housed at three weeks compared with one week post-farrowing. Overall piglet mortality was positively correlated with mortality in the multi-suckling pen for piglets group housed at one week (r = 0.61: P<0.05) and at two weeks post-farrowing (r = 0.62: P<0.05) but not for piglets group housed at three weeks post-farrowing. In conclusion, overall piglet mortality could be reduced if sows and piglets are group housed at three weeks post-farrowing and piglet survival the first week post-farrowing is improved

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Time taking for the nursing suckling interactio