Workers exposed to toluene develop many central and autonomic nervous symptoms. It has been suggested that the effects of toluene on the central nervous system may be detectable by EEG. In the present experiments, changes in EEG and behaviour of rats exposed to toluene were monitored in an attempt to clarify the relationship between exposure to toluene and central nervous system reaction. Chronically implanted electrodes were used in Wistar albino male rats to record EEG in cortex and hippocampus, cervical EEG and pulse rate. The rats were exposed to 4000 ppm, 2000 ppm and 1000 ppm toluene vapour for four hours. The sleep cycle was divided into five phases (wakeful, spindle, slow-wave, preparadoxical and paradoxical) judged by the cortical and hippocampal EEGs, the cervical EMG, and behaviour. This classification should be useful in assessment of the effects of toluene on the central nervous system. In our experiments, the changes in the sleep cycle suggest that 4000 ppm and 2000 ppm of toluene vapour disturb the sleep, and 1000 ppm of toluene vapour prevents sleep entering the slow-wave phase but facilitates its entry into the paradoxical phase. The changes of EEG components were peculiar to each concentration. The results suggest, in effect, that analysis of the changes in the EEG components would be helpful as an index to the reaction of the central nervous system to toluene vapour.

High-speed liquid chromatography employing an ultraviolet photometric detector has been applied to the simultaneous determination of hippuric and m-methylhippuric acids in urine. Reversed-phase partition chromatography is carried out on a muBondapak C18 column with methanol-water as the eluent system. This method obviates the necessity for isolation or reaction of these acids before assay. The only pretreatment necessary is extraction of sample with ethyl acetate. A linear relationship is obtained between the peak heights and the hippuric or m-methylhippuric acid concentrations. Mean recovery of hippuric and m-methylhippuric acids in urine is 99.8% and 99.3% respectively. The determination of hippuric acid by this method gives lower concentrations in normal urine than does the colorimetric method of Umberger and Fiorese (1963).

A gas chromatographic method was applied to the determination of the urinary glycine conjugates, hippuric, o-, m- and p-methylhippuric acids. These were extracted with ethyl acetate from urine after acidification with hydrochloric acid. The internal standard solution (heptadecanoic acid methanol solution) was added before extraction and a diazomethane-ether-ethanol solution was subsequently added to the dried extracts. The methylated residues were dissolved in methanol and injected into a gas chromatograph as described by Buchet and Lauwerys (1973). By the combined use of gas chromatography and mass spectrometry the methyl esters of hippuric acid and m-methylhippuric acid were identified in the urine of a volunteer who had been exposed to toluene and m-xylene vapours. When the urine specimen contained salicyluric acid (a urinary metabolite of salicylic acid) two sharp peaks were observed. The faster peak coincided with m- or p-methylhippuric acid. The upper limit of urinary hippuric acid concentration in healthy subjects with no occupational exposure was calculated by this method to be 1.026 microgram/ml (fiducial limit 5%) after correction to 1.024 for variation in urinary density.

The incidence of lead poisoning in industry has fallen dramatically since the beginning of the twentieth century. This reduction has been partly attributable to increased awareness, improved ventilation and hygiene facilities, and technical changes which have allowed other substances to replace lead, but improved medical surveillance of workers exposed to lead in certain defined industries has also been important. Not all industries where lead exposure can occur are at present covered by specific regulations dealing with lead, however. We report the diagnosis and treatment of eleven oxyacetylene metal burners involved in the demolition of a railway station, who rapidly developed frank lead poisoning. The most suitable measurements to employ in evaluating such a population are considered. The selection, based on blood lead and haemoglobin measurements, of those who should receive further treatment is discussed. Symptoms were found to be more nearly related to indices of effect or toxicity of lead than to indices of exposure or absorption. The effects of chelation therapy upon symptoms, blood lead, haemoglobin and urinary porphyrins are recorded. The need for careful follow-up is illustrated.

Six hundred and ten coke oven personnel were studied retrospectively over a period of 11 years (1954-65). During this time 82 died, 88 retired and 80 left, but all were treated. The Standardised Mortality Ratios (SMRs) have been calculated for four principal causes which have then been further analysed into 30 subgroups. The work was limited because the population was small and the records not detailed enough to analyse the mortality rates according to environmental exposures. Differences between SMRs obtained at the two works were quite marked (73 and 98) and the overall SMR of 85% was better than expected. The observed number of deaths from respiratory disease, malignant neoplasms and all other causes excluding cardiovascular, was very near that expected, but the numbers of deaths from cardiovascular disease and in particular arteriosclerotic disease, showed a significant deficit.

Some details of the physics of xeroradiography, and the bearing these have on films of the lung obtained by this technique, are discussed. In experiments designed to obtain useful films with a minimum of radiation exposure it was found that an exposure range of 10-30 mas at 200 kV at 1.35 m (4 1/2 ft) without a grid or air gap gave very satisfactory results. The positive model of development was considered to give more information than the negative mode. One hundred and fourteen miners who had been exposed to silica dust, asbestos dusts or both, were examined by this technique. The xeroradiographs were compared with silver halide films taken at 200 kV. The xeroradiographs were considered to be superior in several respects, especially in the delineation of vascular shadows, normal and abnormal linear opacities. Linear opacities in asbestos-exposed subjects were better shown on the xeroradiographs and were occasionally seen on these films when the 200 kV conventional film was entirely normal. Small rounded opacities of silicosis were very poorly shown on the xeroradiographs. Pleural thickening and pleural plaques may be very well demonstrated.

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ABSTRACT Exposure of persons to conditions at work may involve some risk to health. It is not possible always to ensure that exposure can be kept below a level from which it may be categorically stated that there is no risk. The decision that has to be made, what ought to be done, poses an ethical problem. What principles are available for examining such ethical problems? Two theories from the study of ethics seem relevant. On the one hand Intuitionism asserts that we possess a moral sense which, correctly applied, enables us to determine what is a right action. The familiar use of 'conscience' and the teachings of some of the influential Western religions follow this theory. On the other hand Utilitarianism (in particular Objective Utilitarianism) asserts that we may judge the rightness of an action by looking at its consequences. This theory, translated into legislative reform, has provided a substantial basis for much of the social reforming legislation of the last century. In economic terms it appears as cost benefit analysis. Despite its attraction and almost plausible objectivity, Utilitarianism requires the quantification and even costing of consequences which cannot always be measured (for example, emotions) but which from an important part of the totality of life. Decisions about the right course of action are required politically but cannot always be made objectively. They may require an element of judgement—a correct application of the moral sense—to use the Intuitionists' phrase. Doctors, used to making ethical decisions in the clinical setting, must examine carefully their role when contributing to ethical decisions in the industrial setting.

ABSTRACT Analysis for chromosome aberrations in human peripheral blood lymphocytes has been developed as an indicator of dose from ionising radiation. This paper outlines the mechanism of production of aberrations, the technique for their analysis and the dose-effect relationships for various types of radiation. During the past ten years the National Radiological Protection Board has developed a service for the UK in which estimates of dose from chromosome aberration analysis are made on people known or suspected of being accidentally over-exposed. This service can provide estimates where no physical dosemeter was worn and is frequently able to resolve anomalous or disputed data from routine film badges. Several problems in the interpretation of chromosome aberration yields are reviewed. These include the effects of partial body irradiation and the response to variations in dose rate and the intermittent nature of some exposures. The dosimetry service is supported by a research programme which includes surveys of groups of patients irradiated for medical purposes. Two surveys are described. In the first, lymphocyte aberrations were examined in rheumatiod arthritis patients receiving intra-articular injections of colloidal radiogold or radioyttrium. A proportion of the nuclide leaked from the joint into the regional lymphatic system. In the second survey a comparison was made between the cytogenetic and physical estimates of whole body dose in patients receiving iodine 131 for thyroid carcinoma.

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