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Biomedical subjects

P S Phillips

Publications and source records attributed to P S Phillips.

At least 19 recordsLinked to original sources
PubMed2006

The value of Seasonal Correction Factors in assessing the health risk from domestic radon: a case study in Northamptonshire, UK.

Following an intensive survey of domestic radon levels in the United Kingdom (UK), the former National Radiological Protection Board (NRPB), now the Radiation Protection Division of the Health Protection Agency (HPA-RPD), established a measurement protocol and promulgated Seasonal Correction Factors applicable to the country as a whole. Radon levels in the domestic built environment are assumed to vary systematically and repeatably during the year, being generally higher in winter. The Seasonal Correction Factors therefore comprise a series of numerical multipliers, which convert a 1-month or 3-month radon concentration measurement, commencing in any month of the year, to an effective annual mean radon concentration. In a recent project undertaken to assess the utility of short-term exposures in quantifying domestic radon levels, a comparative assessment of a number of integrating detector types was undertaken, with radon levels in 34 houses on common geology monitored over a 12-month period using dose-integrating track-etch detectors exposed in pairs (one upstairs, one downstairs) at 1-month and 3-month resolution. Seasonal variability of radon concentrations departed significantly from that expected on the basis of the HPA-RPD Seasonal Correction Factor set, with year-end discontinuities at both 1-month and 3-month measurement resolutions. Following this study, monitoring with electrets was continued in four properties, with weekly radon concentration data now available for a total duration in excess of three and a half years. Analysis of this data has permitted the derivation of reliable local Seasonal Correction Factors. Overall, these are significantly lower than those recommended by HPA-RPD, but are comparable with other results from the UK and from abroad, particularly those that recognise geological diversity and are consequently prepared on a regional rather than a national basis. This finding calls into question the validity of using nationally aggregated Seasonal Correction Factors, especially for shorter exposures, and the universal applicability of these corrections is discussed in detail.

Air Pollution, Indoor↗
PubMed2006

Radon mitigation in domestic properties and its health implications--a comparison between during-construction and post-construction radon reduction.

Although United Kingdom (UK) Building Regulations applicable to houses constructed since 1992 in Radon Affected Areas address the health issues arising from the presence of radon in domestic properties and specify the installation of radon-mitigation measures during construction, no legislative requirement currently exists for monitoring the effectiveness of such remediation once construction is completed and the houses are occupied. To assess the relative effectiveness of During-Construction radon reduction and Post-Construction remediation, radon concentration data from houses constructed before and after 1992 in Northamptonshire, UK, a designated Radon Affected Area, was analysed. Post-Construction remediation of 73 pre-1992 houses using conventional fan-assisted sump technology proved to be extremely effective, with radon concentrations reduced to the Action Level, or below, in all cases. Of 64 houses constructed since 1992 in a well-defined geographical area, and known to have had radon-barrier membranes installed during construction, 11% exhibited radon concentrations in excess of the Action Level. This compares with the estimated average for all houses in the same area of 17%, suggesting that, in some 60% of the houses surveyed, installation of a membrane has not resulted in reduction of mean annual radon concentrations to below the Action Level. Detailed comparison of the two data sets reveals marked differences in the degree of mitigation achieved by remediation. There is therefore an ongoing need for research to resolve definitively the issue of radon mitigation and to define truly effective anti-radon measures, readily installed in domestic properties at the time of construction. It is therefore recommended that mandatory testing be introduced for all new houses in Radon Affected Areas.

Air Pollutants, Radioactive↗
PubMed2006

Identification of tidal and climatic influences within domestic radon time-series from Northamptonshire, UK.

Analysis of data from extended radon concentration time-series obtained from domestic and public-sector premises in the vicinity of Northampton, UK, and elsewhere, confirms that, in addition to the generally recognised climatic influences, 'Earth Tides' and 'Ocean Tidal Loading' drive periodic radon liberation via geophysically driven groundwater level variations. Regression and cross-correlation with environmental parameters showed some degree of association between radon concentration and mean temperature and rainfall. Fourier analysis of radon time-series identified periodicities of the order of 23.9 h (luni-solar diurnal, K(1)), 24.0 h (solar day, S(1)), 168 h (1 week) and 661.3 h (lunar month, M(m)), while cross-correlation with tidal strength demonstrated periodicity of the order of 14 days (lunar-solar fortnight, M(f)). These results suggest that astronomical influences, including tides, play a part in controlling radon release from the soil.

Air Pollutants, Radioactive↗
PubMed2005

Time-integrating radon gas measurements in domestic premises: comparison of short-, medium- and long-term exposures.

To identify the most applicable technology for the short-term assessment of domestic radon levels, comparative assessments of a number of integrating detector types, including track-etch, electret and activated charcoal were undertaken. Thirty-four unremediated dwellings in a high-radon area were monitored using track-etch detectors exposed for one-month and three-month periods. In parallel, one-week measurements were made in the same homes at one-month intervals, using co-located track-etch, charcoal and electret detectors exposed simultaneously, while three of the homes were also monitored by continuous-sampling detectors at hourly intervals over extended periods. Calibration of dose-integrating devices against each other and against continuous-monitoring systems confirmed good responsivity and linearity. Although track-etch, charcoal and electret devices are suitable in principle for one-week measurements, zero-exposure offset and natural radon variability cause many one-week results to be equivocal, necessitating repetition of the measurement. One-week exposures can be reliable indicators in low-radon areas or for new properties, but in high-radon areas, the use of three-month exposures is indicated. This analysis also established confidence limits for short-term measurements.

Air Pollutants, Radioactive↗
PubMed2005

Radon anomalies preceding earthquakes which occurred in the UK, in summer and autumn 2002.

During the course of an investigation into domestic radon levels in Northamptonshire, two hourly sampling real-time radon detectors were operated simultaneously in separate locations 2.25 km apart in Northampton, in the English East Midlands, for a 25-week period. This period of operation encompassed the period in September 2002 during which the Dudley earthquake (magnitude - 5.0) and smaller aftershocks occurred in the English West Midlands, UK. We report herein our observations regarding the occurrence of simultaneous short-period radon anomalies and their timing in relation to the Dudley, and other, earthquakes which occurred during the monitoring period. Analysis of the radon time-series reveals a short period when the two time-series displayed simultaneous in-phase short-term (6-9 h) radon anomalies prior to the main Dudley earthquake. Subsequent investigation revealed that a similar period occurred prior to another smaller but recorded earthquake in the English Channel.

Air↗
PubMed2005

The use of the Montgomery T-tube in difficult paediatric airways.

OBJECTIVE: We report our experience of using Montgomery T-tubes in children. METHOD: A retrospective review of medical records was performed. Data collected included particular clinical circumstances, the details of usage of the tube, and the eventual outcome. RESULTS: Between January 1999 and October 2003, our unit performed 293 tracheostomies, 76 laryngotracheal reconstructions and 31 other major airway procedures in children. 10 children have had a Montgomery T-tube inserted. Nine were boys. In eight cases, the T-tube was used because of severe granulations and subsequent fibrotic narrowing in the subglottis after laryngotracheal reconstruction surgery. These children had undergone between one and four major procedures prior to T-tube placement. In the other two cases, the T-tube was used to stent severe glottic and supraglottic stenosis (due to previous laser surgery for papillomas in one case and congenital ectodermal dysplasia in the other). At the time of T-tube placement the children were aged 2-18 years (median 8 years). The tube was initially fitted so as to protrude above the glottis in all cases. In one case, the T-tube was removed on the first post-operative day. One tube was removed after a week due to severe crusting. One tube blocked after 2 weeks. One child had re-stenosis in the supraglottis necessitating the placement of a T-tube with a longer upper limb. Two children have subsequently died from non-airway causes. Two children still have their T-tube in situ, one of whom is due to have it removed in the next few weeks. Six have been successfully decannulated and are well. CONCLUSIONS: The Montgomery T-tube provides a useful adjunct to the management of a small number of children with the most difficult airway problems. Its use can be problematic, however, and requires awareness of its specific complications. We have confined usage to complex stenoses where a reconstruction would be inappropriate, or (in one instance) to stent an unsupported larynx after revision reconstruction (tracheal resection).

Adolescent↗
PubMed2005

The practical use of electrets in a public health radon remediation campaign.

As part of a long-term assessment of domestic radon in Northamptonshire, England, a batch of 50 commercially available electrets was deployed for nearly 1,000 exposures, individual exposure periods ranging from one to eight weeks. Responsivity was comparable with that of recently-calibrated Durridge RAD-7 continuously-monitoring equipment. Voltage history analysis indicated mean voltage decay during manufacturers' QA assessment of 0.059+/-0.026 Vday(-1), increasing to 0.114+/-0.073 Vday(-1) during storage to first use and to 0.204+/-0.49 Vday(-1) during inter-deployment storage. At a representative elevated radon concentration of 500 Bqm(-3), the resulting perturbation is 3% over a 7-day deployment; at the typical mean Northamptonshire level of 80 Bqm(-3) it approaches 22%. Each electret can be used for up to 25 measurements, which makes the technology attractive for organisational use. It is not suited for deployment by individual householders.

Air Pollutants, Radioactive↗
PubMed2005

Analysis of the individual health benefits accruing from a domestic radon remediation programme.

Although radon can be present within buildings at sufficient levels to pose a health risk, levels can be reduced relatively easily. Recent studies on a group of radon-remediated homes, based on assessment of collective population-average risk coefficients, have estimated the benefits and cost effectiveness accruing from remediation and have confirmed that domestic remediation in UK radon Affected Areas would result in significantly reduced cancer risks to the population in those areas. Although the population-average approach used hitherto has applied occupancy and lung-cancer risk factors, these are potentially misleading in assessing discrete populations. The study reported here uses the recently developed European Community Radon Software (ECRS) to quantify individual risks in a sample of householders who remediated their homes following indications that radon levels exceeded the action level. The study proceeds from population-averaged to 'individual risk' evaluation, successfully comparing individual and collective risk assessments, and demonstrates that those who remediate are not representative of the general population. Health benefits accruing from remediation are three times lower than expected, largely because remediators are older, live in smaller households, and smoke less than the population average, leading to the conclusion that the current strategy employed in the UK is failing to target those most at risk.

Adolescent↗
PubMed2005

Does a specialist voice clinic change ENT clinic diagnosis?

General ENT clinics lack the high quality diagnostic equipment and multidisciplinary advice that is available in the voice clinic. We wished to find out if referral to a specialist voice clinic from general ENT consultant clinics resulted in a change in diagnosis. Lists of voice clinic attendees were reviewed between January 2003 and May 2004. Notes were obtained for 20 patients who attended voice clinic after referral from a general ENT clinic: 3 had no diagnosis on referral to voice clinic, a diagnosis was given after attendance; 8 had their referring diagnosis changed by attendance; and 9 had no change. The voice clinic adds diagnostic value to the service available in general ENT clinics.

Diagnosis, Differential↗
PubMed2004

Radon and 'King Solomon's Miners': Faynan Orefield, Jordanian Desert.

Concentrations of 222Rn were measured in ancient copper mines which exploited the Faynan Orefield in the South-Western Jordanian Desert. The concentrations of radon gas detected indicate that the ancient metal workers would have been exposed to a significant health risk and indicate that any future attempt to exploit the copper ores must deal with the hazard identified. Seasonal variations in radon concentrations are noted and these are linked to the ventilation of the mines. These modern data are used to explore the differential exposure to radon and the health of ancient mining communities.

Environmental Exposure↗
PubMed2004

Statin myotoxicity is associated with changes in the cardiopulmonary function.

The mechanism of the muscle toxicity associated with lipid-lowering therapy remains obscure. Pathological and biochemical findings in patients with statin myotoxicity suggest impaired fatty acid oxidation. Exhaled gas analysis can be used to assess substrate utilization including fatty acid oxidation. In order to determine if muscle toxicity due to lipid-lowering therapy might be related to abnormalities in lipid oxidation, exhaled gas analysis was performed in the fasted state on 11 patients subsequent to statin-associated myositis reactions. Results were compared to those of 16 normal controls who were measured both on and off statin therapy. Post-myositis patients showed a depressed anaerobic threshold (AT) (P=0.009) compared to controls while age-adjusted maximal oxygen consumption (VO2max) and ventilatory efficiency (VE/VCO2) were not significantly different. The fasting respiratory exchange ratio (RER) of post-myositis patients off statins was abnormally increased (P=0.00001) as was their S1-slope (P=0.023). Controls demonstrated a significant increase in their RER while taking statins consistent with decreased lipid oxidation (P <0.00001). These findings suggest that abnormal lipid oxidation in certain patients may predispose them to the myotoxicity caused by lipid-lowering therapies.

Aged↗
PubMed2004

Using the European Community Radon Software to estimate the individual health benefits of a domestic radon remediation programme.

Radon can be present in domestic properties at high enough levels to pose a health risk. Such levels can usually be reduced by simple means. Studies on a group of radon-remediated homes in Northamptonshire, a radon affected area, have estimated the health benefits and cost effectiveness from remediation and have shown that remediation can be justified. These assessments have been based on collective population-average risk coefficients. The advent of the European Community Radon Software (ECRS) permits the consideration of individual risk. In particular, it can take into account individual smoking habits, which significantly affect risk, as current scientific opinion is that risks from radon and smoking are multiplicative. This note indicates how the software can be used, and the usefulness of this approach.

Air Pollution, Radioactive↗
PubMed2004

Radon in the workplace: implications of studies of post-remediation monitoring.

Radon gas has been shown to cause an increased incidence of lung cancer. In affected areas, levels in the overground workplace can be sufficiently high to be a health risk and remediation is required. In the UK, the workplace Action Level is 400 Bq m(-3). The variation of radon levels in the workplace was studied both before and after remediation. In most rooms, remediation resulted in a greater reduction at night than during the working day. The dose reduction, and therefore the health benefit, to workers is less than that predicted by the drop in radon averaged over 24 h. In order to obtain a health benefit to 75% of workers in our series, the 24 h average radon level in each room must be reduced to <225 Bq m(-3). It is recommended that UK Regulatory Agencies adopt a post-remediation workplace Action Level of 225 Bq m(-3).

Air Pollutants, Occupational↗
PubMed2004

A mixed thyroglossal cyst.

The case is described of a boy who presented at age six months with symptoms and signs of a thyroglossal cyst, which seemed to be confirmed by ultrasound findings. The cyst slowly increased in size, and eventually the patient underwent Sistrunk's procedure at age four years. Histology showed that the cyst was in fact a mixed thyroglossal and dermoid cyst. This casts doubt on the doctrine that thyroglossal cysts and dermoid cysts are anatomically and histologically separate entities, and strengthens the view that these cysts should be more appropriately named 'thyroglossal abnormalities'.

Child, Preschool↗
PubMed2003

The haemodynamics of multiple sequential stenoses and the criteria for a critical stenosis.

INTRODUCTION: Occlusive arterial disease is usually multi-focal but the cumulative functional effect of multiple arterial stenoses is not fully understood. We tested the hypothesis that a non-linear pressure/flow model (DeltaP=k1Q+k2Q2) that has been validated for single stenoses is also valid for multiple stenoses arranged in series. METHOD: The pressure/flow characteristics of three dissimilar modelled stenoses were measured individually and in different combinations using a hydraulic flow rig. RESULTS: The combined effect of multiple stenoses fitted the non-linear model accurately (R2=0.99) and approximated to the sum of the k1 and k2 parameters for each individual stenosis. For multiple stenoses the cumulative k1 was less than the predicted and the series order of the individual stenoses consistently altered the combined effect. CONCLUSIONS: A sequence of multiple stenoses is functionally equivalent to a single equivalent stenosis of greater functional severity and can be represented by a single viscous (k1) and inertial (k2) pressure loss coefficient. This finding allows the term 'critical stenosis' to be defined precisely in terms of the functional effect rather than the anatomical appearance, particularly where disease is multi-focal.

Arterial Occlusive Diseases↗
PubMed2003

Assessment of health risks to skin and lung of elevated radon levels in abandoned mines.

Radon, together with its progeny, is present in high levels in some underground sites. Radon is known to increase the risk of lung cancer, while increased levels of radon decay products on the skin surface have been implicated in skin cancer induction and at sufficient levels might cause deterministic effects such as erythema. Although radon levels in working mines are controlled, radon in abandoned mines can reach very high levels, which would result in an occupant exceeding recommended annual exposure limits in less than 2 h in some mines. The relative importance of dose limits for the lung, skin cancer, and deterministic effects is discussed in the light of practical experience.

Air Pollutants, Radioactive↗
PubMed2002

The costs and benefits of radon remediation programmes in existing homes: case study of action level selection.

Radon gas can be present within buildings at sufficiently high levels that it becomes a health risk. Such levels can be reduced, and so radon remediation programmes in the home in UK Affected Areas should result in reduced risks to the population. This paper considers the benefits and costs of the domestic radon remediation programme in Northamptonshire, UK, and considers the implications of the choice of Action Level, in view of the adoption of different levels in many countries. A programme with a higher Action Level will cost less, and target those most at risk, but will be less cost effective. In addition, a higher Action Level leaves a higher residual dose and risk to the remaining population. Such doses are higher than and inconsistent with the radiation dose limits for the general public in the EU Basic Standards Directive.

Cost-Benefit Analysis↗