The harmful effects of ionising radiation are widely acknowledged. It has been reported that young children, particularly girls, have a higher sensitivity to radiation than adults. However, the exact detrimental effects of radiation, particularly at the low doses used in routine diagnostic radiography, are unknown and the subject of much controversy. Computed tomography (CT) accounts for about 9% of all radiological examinations but is responsible for 47% of medical radiation dose. Approximately 11% of CT examinations performed are in the paediatric population, but the long-term hazards of CT are unknown.

A prospective single centre study has been performed to assess dose-area product (DAP) values in children having fluoroscopic examinations and to revise local diagnostic reference levels (DRLs). DAP measurements for 2658 examinations performed in a dedicated fluoroscopy room over a period of 21 months were analysed. Data for the eight most commonly performed examinations (2215 cases) are presented. DAPs (75th centile) for upper gastrointestinal studies and micturating cystograms are substantially lower (by a factor of between x 5 and x 25) than the current national reference doses (NRDs), with some of the median values being 50 times lower. The small DAP values in all examinations demonstrate the substantial reduction in dose and consequent risk that can be achieved when both equipment performance and operator technique are optimized. Whilst we recognize that different institutions will have differing practices, it is important that practitioners are aware of the range of DAPs achievable and that NRDs do not necessarily represent best practice, and may falsely reassure.

The United States Environmental Protection Agency has developed a new procedure, the Toxicity Characteristic Leaching Procedure (TCLP), to more effectively simulate the leaching of hazardous materials from waste disposed in an unsecured landfill. The procedure involves (1) an 18-h extraction of a sample with sodium acetate solution and (2) the subsequent analysis of the leachate for metals, pesticides, semivolatile organics, and volatile organic compounds. To validate the method for all but the volatile organic analytes, three waste samples at two different pH levels were sent to 23 different volunteer government and commercial laboratories for extraction and analysis. For validation of the TCLP procedure involving determination of volatile organic compounds, two fortified waste samples were distributed to each participating laboratory. The results and statistical analysis of this collaborative test are presented and discussed. These results indicate that the TCLP can be applied consistently by a diverse group of organizations for the analyses considered in this study.

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Environmental samples are analyzed for organochlorine pesticides/PCB's as part of the Environmental Protection Agency's (EPA) Superfund Contract Laboratory Program (CLP). A new protocol is required because laboratories have difficulty meeting the present data acceptability criteria and because the surrogate now used is more chemically labile than the analytes determined with the protocol. The new pesticide/PCB protocol specifies an ultrasonic extraction procedure for soil and either continuous liquid-liquid or separatory funnel extraction of water. It describes clean-up procedures using gel permeation chromatography, adsorbtion columns and mercury, copper or tetrabutylammonium sulfate for sulfur removal. The protocol requires a dual gas chromatography (GC) column quantitation of 17 single component pesticides and nine multicomponent pesticides/PCB's using electron capture detection (ECD). The quality assurance/quality control (QA/QC) requirements include 12-hour GC performance checks, instrument and method blank requirements, matrix spike/matrix spike duplicate analyses every 20 samples and periodic performance checks of clean-up techniques. Validation of the protocol is being accomplished according to EPA guidelines for determining ruggedness, precision, bias, detection limits, and sensitivity.