Polynuclear aromatic hydrocarbons in the United Kingdom environment: a preliminary source inventory and budget.

This paper presents the first attempt to quantify the production, cycling, storage and loss of PAHs in the UK environment. Over 53 000 tonnes of sigmaPAHs (sum of 12 individual compounds) are estimated to reside in the contemporary UK environment, with soil being the major repository. If soils at contaminated sites are included, this estimate increases dramatically. Emission of PAHs to the UK atmosphere from primary combustion sources are estimated to be greater than 1000 tonnes sigmaPAHs per annum, with over 95% coming from domestic coal combustion, unregulated fires and vehicle emissions. It is estimated that approximately 210 tonnes of sigmaPAH are delivered to terrestrial surfaces each year via atmospheric deposition. Therefore, inputs of PAHs to the UK atmosphere outweigh the outputs by a factor of over 4. This may be explained by enhanced particulate deposition near point sources, PAH degradation in the atmosphere and transport away from the UK with prevailing winds. Disposal of waste residues is estimated to contribute a further 1000 tonnes of sigmaPAH per year to the terrestrial environment. It is illustrated that the use of creosote has the potential to release considerable quantities of PAHs to the UK environment. Temporal trends in PAH cycling are then considered. There is good evidence to suggest that air concentrations and fluxes to the UK surface are now lower than at any time throughout this century. Nonetheless, the UK sigmaPAH burden is still increasing at the present time, principally through retention by soils. However, there are marked differences in the behaviour of individual compounds: there is evidence, for example, that phenanthrene concentrations in soils have declined since the 1960s, although soil concentrations of benzo[a]pyrene and other heavier PAHs have continued to increase through this century. Volatilisation of low molecular weight PAHs accumulated in soils over previous decades may be making an important contribution to the current atmospheric burden. The major uncertainties identified by data on this budget are: (1) the lack of PAH concentrations in some environmental matrices; (2) the possible importance of contaminated soils as a major repository and source of PAHs; (3) the lack of emission data (especially vapour phase releases) for some PAH sources; (4) the importance of biodegradation and volatilisation as loss mechanisms for low molecular weight PAHs in soils; and (5) the importance of creosote use in the PAH cycle.

Survey of urological centres and review of current practice in the pre-operative assessment of prostatism.

A survey of 24 urological centres has shown a wide variation in the routine pre-operative assessment of patients being considered for prostatectomy. Imaging of the urinary tract by intravenous urography (IVU) or ultrasound (US) is performed in 21/24 centres (79%) and plain films in 16/24 (67%). Post-micturition residual volume (PMRV) is estimated quantitatively in 10/24 centers (42%). Although there is little agreement on what constitutes a significant PMRV, a large PMRV leads to increased likelihood of operation, and earlier operation. Peak urine flow rate (Q max) is measured in 19/24 centres (79%). The significance of these findings is discussed.

Is pre-operative imaging of the urinary tract worthwhile in the assessment of prostatism?

The reports of routine pre-operative imaging investigations performed on patients presenting with symptoms of uncomplicated benign prostatic hypertrophy were compared with management decisions and clinical outcome. In 175 patients with prostatism no urological abnormality which altered management was discovered on plain films of the abdomen and pelvis and ultrasound of the urinary tract which were performed routinely. Post-micturition residual volume (PMRV), estimated by ultrasound, was compared with the maximum urine flow rate (Q max) in 57 patients. PMRV showed negative correlation with Q max. Both high PMRV and low Q max were associated with the urologist's decision to operate, but multiple logistic regression revealed that ultrasound residual volume was not a significant predictor of operation when adjusted for Q max. Urologists in this hospital therefore use flow rates as the primary indication of the need to operate. We suggest that no routine pre-operative imaging need be performed in patients presenting with prostatism.