Occupational exposures worldwide and revision of international standards for protection.

United Nations Scientific Committee on the Effects of Atomic Radiation (UNSCEAR) has become the world authority on the levels and effects of ionising radiation. Since 1975, UNSCEAR has evaluated inter alia the level of occupational exposure worldwide. Based on revised questionnaires, more detailed information is now available. The results of the last evaluation (1995-2002) will be shown in the paper. Lessons learned from the responses by UN Member States will be given, as well as an outline of plans for data collection in future cycles. The requirements for protection against exposure to ionising radiation of workers, the public and patients are established in the International Basic Safety Standards for Protection against Ionising Radiation and for the Safety of Radiation Sources (BSS), published in 1996. As a result of a review of the BSS in 2006, the International Atomic Energy Agency (IAEA) started a process for the revision of these standards in 2007. International organisations including the joint sponsoring organisations of the BSS-IAEA, FAO, ILO, OECD/NEA, PAHO and WHO--as well as potential new joint sponsoring organisations of the revised BSS--the European Commission and UNEP-were involved from the beginning in the revision process. The paper also provides a summary of the status of the Draft Revised BSS and describes the new format. The paper focuses, in particular, on requirements for the protection of workers as well as recordkeeping requirements, which provide the legal basis for the collection of specific data; these data are of the type that can be used by UNSCEAR.

Emergency management in the early phase.

An overview of response management in the early phase of an emergency at a nuclear installation is provided from a systems approach. This starts with the recognition of response goals, and using detailed analyses of threats, past experience, international law and principles, a response strategy is developed. The process is illustrated for the case of severe accidents at pressurized water reactors (PWRs) and identifies the need for and nature of: emergency classification based on plant conditions, notification, radiological monitoring and assessment strategies, operational criteria for implementing protective action decisions and management of public information. From the strategy detailed, functional and infrastructure requirements can be defined. The paper also presents some reflections on the key differences between response to emergencies arising from accidents and those arising from deliberate acts; on the preparedness and response capabilities of States, highlighting areas where generic improvements are needed and how best to achieve that.

Vitrectomy for phacolytic glaucoma in a patient with ectopia lentis et pupillae.

This case report highlights the successful management, by vitrectomy alone, of a case of chronic phacolytic glaucoma secondary to a dislocated hypermature lens in the vitreous of a patient with ectopia lentis et pupillae (ELP). The features and complications of ELP are discussed.

A cost-benefit analysis of long-term management options for forests following contamination with 137Cs.

This paper provides a description of a cost-benefit analysis applied to determine the cost effectiveness, or otherwise, of nine management strategies potentially applicable to forests contaminated with 137Cs. The management strategies were considered singly and in a number of likely combinations. A management strategy was considered to be cost-effective if it resulted in a lower overall monetary detriment than was incurred if use of the contaminated forest was continued on a 'business as usual' basis. Only the banning of mushroom collection and restriction of public access proved to be cost-effective management strategies on the basis of this definition. However, even these strategies only proved cost-effective at high levels of 137Cs contamination, at which net savings in detriment in the form of public dose were achieved. Cost-effective savings of doses to forest workers were never achieved at any of the contamination levels considered in this study. It is suggested that novel alternative uses of contaminated forests are required which could provide added value to the standing crop in return for small increases in public and worker doses. One such use might be biofuel production.

Beyond retinal screening: digital imaging in the assessment and follow-up of patients with diabetic retinopathy.

Many screening methods are available for detecting diabetic retinopathy. However, once patients develop retinopathy, it is unclear as to what method should be used for their review. We describe a novel and integrated system for the screening and treatment of diabetic retinopathy using high street optometrists for primary screening and digital imaging as a secondary screening tool, with referral to a joint retinal clinic only where ophthalmological intervention may be required. Of 3586 patients screened by optometrists, 328 were classified as having moderate/severe pre-proliferative retinopathy or diabetic maculopathy. Patients with proliferative retinopathy (1% of the total) were recalled directly to the joint retinal clinic. A consecutive sample (281) of these patients, together with a further 100 classified by the optometrists as having no or background retinopathy were compared using digital images and standard 35 mm colour transparencies. These, together with the original optometrist reports, were reviewed independently and individually by an ophthalmologist. A further sample of 124 patients who had undergone both digital imaging and ophthalmologist slit-lamp examination were also compared. Comparison of 35 mm colour transparencies with optometrist reports showed the latter had a sensitivity for detecting sight-threatening retinopathy (STR) of 62%, a specificity of 84%, and a kappa score of 0.62. The results for digital images were 90%, 97%, and 0.90, respectively, although the extent of retinopathy was under-reported in 10 patients. With ophthalmologist slit-lamp examination as the gold standard, the sensitivity of digital imaging was 90% with a substantial level of agreement between them (kappa 0.61). We conclude that digital images provide an efficient method for the follow-up of patients with established or previously treated retinopathy.

Blurred vision and high blood pressure in a young woman.

A 41-year-old woman presented with a short history of blurred vision. She had a 6-year history of refractory hypertension which had been treated with a variety of drug regimens. She was found to have bilateral branch retinal vein occlusion. Retinal vein occlusion is a recognised complication of hypertension but simultaneous involvement of both eyes is extremely rare. Following this episode, blood pressure control has improved without change in drug therapy, suggesting that treatment compliance may partly explain the previous difficulties.

Impaired response to alloantigens in murine biliary obstruction.

Male Lewis strain rats underwent bile duct ligation and division (BDL), selective hepatic duct ligation (SHL), simple ligation and recanalization (RCN), or sham celiotomy (SC). Unoperated rats served as normal controls (NC). At intervals of 1, 2, and 3 weeks postoperatively, the popliteal lymph node assay was used to study host versus graft (HVG) response. LBN-F1 splenocytes (5 x 10(6)) were injected into the hind foot pads, and the contralateral foot pad was injected with medium as a control. The popliteal lymph nodes were removed and weighed 7 days later. In the BDL group, HVG response was significantly impaired at 1 (BDL, 12.9 +/- 5.1 mg; SC, 21.6 +/- 2.6; NC, 22.4 +/- 9.4; P < 0.005, BDL vs SC or NC), 2 (BDL, 12.6 +/- 5.6; SC, 19.1 +/- 3.0; NC, 15.8 +/- 5.8; P < 0.001, BDL vs SC), and 3 weeks (BDL, 8.9 +/- 3.9; SC, 21.7 +/- 6.3; NC, 16.7 +/- 3.8; P < 0.001, BDL vs SC or NC). SHL did not cause hyperbilirubinemia or impair the HVG response at 2 weeks (SHL, 17.2 +/- 4.5; NC, 16.7 +/- 7.4). The serum bilirubin was normal 2 and 3 weeks after RCN, and the HVG response was normal in both groups; however, the HVG response was somewhat lower at 2 weeks (RCN, 12.1 +/- 2.1) than at 3 weeks (RCN, 18.2 +/- 4.4; P < 0.01, RCN 2 weeks vs RCN 3 weeks). BDL causes significant impairment in the murine response to alloantigens as measured by the popliteal lymph node assay.(ABSTRACT TRUNCATED AT 250 WORDS)

Derived emergency reference levels for the introduction of countermeasures in the early and intermedia phases of accidental releases to atmosphere

When an unplanned release of radioactive material to atmosphere is identified or suspected, environmental survey teams under the direction of the operator of the nuclear installantion are sent into the anticipated path of the plume of activity to make measurements and take samples. In the case of external dose, measurements can be easily related to projected doses to individual memebers of the public. However, the radiological interpretation of measurements of airbonrne activity concentrations, of activity levels on soil, pasture grass and crops, and of radionuclide levels in milk and drinking water requieres the use of quantities which relate the appropriate environmental concentration to an implied dose. The derivation of these quantities is not a simple procedure, particularly when they are to be generally applicable. It involves interpretation of the primary dose criteria which have been established for planning the introduction of countermeasures, making assumptions about the habits of the group of people who could receive the highest doses, and using mathematical models to obtain a relationship between dose and activity concentrations in environmental materials. The paper describes recent work by the National Radiological Protection Board (NRPB) to provide guidance on derived quantities for use in the United Kingdom (UK). While some of the numerical values obtained are specific to UK condiditons, the methods are more generally applicable. (AU)

An assessment of the radiological impact of the Windscale reactor fire, October 1957.

On the 10th and 11 October 1957 a fire in the No 1 Pile at the Windscale establishment in Cumbria led to an uncontrolled release of activity to the atmosphere. The resultant cloud subsequently dispersed and radionuclides could be detected over England, Wales and parts of northern Europe. The extensive environmental measurements which were made during and after the release enabled a fairly accurate estimate to be made of the radiation doses to the most exposed individuals in the local population. Until recently, no estimates of the population dose resulting from the release had been published. This paper describes assessments which have been made by the NRPB of the population or collective dose from the release and of the possible associated health impact. In addition to the fission products that escaped, radionuclides were released from materials undergoing irradiation in the pile at the time of the fire. The assessment has included the results of a review of previously unpublished data which established the quantity of these nuclides released and considers their impact on both individual and population doses. The collective effective dose equivalent commitment from the release is estimated to have been 2.0 x 10(3) man Sv. The route of exposure which contributed the most to the collective dose was the inhalation pathway. Iodine-131 was the most important radionuclide, contributing nearly all of the collective dose to the thyroid and a large part of the collective effective dose. Polonium-210 and caesium-137 also made significant contributions; that from caesium-137 came in the longer term via external irradiation from ground deposits and the ingestion of contaminated foodstuffs. The methodology used in the study has been validated to a certain degree by comparing the predicted levels of individual thyroid activity and those measured directly in the weeks following the accident in London, Leeds and Cumbria.

Models for the transfer of radionuclides in cattle for use in radiological assessments.

In performing assessments of the radiological impact of releases of radioactive materials to the environment, mathematical models are required to enable the transfer through various parts of the environment and hence the dose to man to be predicted. The nature of the models and their degree of complexity depend largely upon the particular applications in which they are to be used. Two types of model of differing degrees of complexity for predicting the transfer of strontium, caesium and iodine in cattle have been developed at NRPB . They form part of a general model for the transfer of radionuclides through terrestrial foodchains . The first is a relatively simple model based on the use of equilibrium transfer factors, while the second is an improved but more complex model which incorporates the extra features necessary to provide a reasonable representation of the time dependence of transfer to milk and to meat. Comparisons of the results using the two types of model in some situations of radiological interest have been performed. From these comparisons conclusions have been drawn about the adequacy and pertinence of the use of each model type in different situations.

Retinal detachment surgery without cryotherapy.

The authors have performed 43 retinal detachment operations omitting the use of cryotherapy or any other type of retinal adhesion. Only a full thickness buckling procedure has been performed with drainage of subretinal fluid in some cases. The cases were carefully selected and the follow-up period has been from 1 to 3 1/2 years. Redetachment has not occurred if the original hole was free of traction (round holes) but has so far occurred in 3 cases where traction was present.

Treatment of rhegmatogenous detachment without apparent holes.

In a series of cases of retinal detachment without visible holes, failure was not associated with local procedures but, as in all cases of retinal detachment, with membrane formation and retinal fibrosis. In total detachments with no localizing signs we favoured the encirclement procedure. In this group of thirty cases of retinal detachment in which no hole could be found we achieved the surprisingly high success rate of 87 per cent, but in as many as seventeen of the thirty cases a local buckle was applied to the most likely site of the tear. We therefore feel that the principle of performing the least traumatic procedure, i.e. a local procedure, can still be followed in a considerable number of these challenging cases.

Lensectomy.

Lensectomy is a new technique of lens extraction by which lens material is cut and aspirated through a fine-bore needle. The technique is simple and atraumatic. The small limbal incision, which does not require suturing, has the advantage of reducing the risk of vitreous loss and the amount of surgically-induced astigmatism to a minimum. Instruments designed primarily for vitreous surgery were used in the removal of cataracts from seventy eyes. This preliminary report shows that this new approach offers several advantages over conventional methods in selected cases. It appears to be of particular value in the management of cataracts secondary to chronic anterior uveitis. It is also a good alternative in the treatment of traumatic, presenile, and congenital or juvenile cataracts. Lensectomy is not a suitable technique for the removal of calcified lenses or those with hard nuclei. Possible complications include endothelial damage, loss of lens matter into the vitreous, and retinal detachment.

Vitrectomy technique in anterior segment surgery.

Instruments designed primarily for vitreous surgery were used in 74 anterior segment operations. In each case the instrument was introduced into the eye through a limbal incision. This preliminary report shows that this new approach offers several advantages over conventional methods in selected cases. It is of particular value in the management of presenile and complicated cataracts and in the removal of capsulo-lenticular remnants and pupillary membranes. A larger number of cases and longer follow-up are necessary to define further the specific indications and limitations of this technique.