Environmental lead concentrations today are grossly increased over the natural levels, even far away from cities. Nevertheless, the results of the EEC survey' (see box) seem reasonably reassuring so far, even for children specially exposed to lead.But even 2% of children exceeding the limit of 1 69 Fmol/l (35 ,tg/100 mg) might be too many-that is, if slightly raised levels can cause subtle neurological impairment (see last article, p 1622).Young children tend to have higher blood lead concentrations, which will not be apparent from blood samples taken when they are older. Some studies carried out near factories producing lead pollution have shown considerably raised blood lead concentrations in many preschool children, and also mothers. 8-8 ,ug/m3 in West London.' Indoor values might be around two-thirds of the outdoor ones, but the two readings are about the same in some houses' 3; a bungalow 34 m from a motorway had a concentration of 4 8 Lg/m3.7 The Lawther Report concludes that few people in Britain are likely to be exposed to long-term averages over 1 ,ug/m3; that for most city dwellers the concentration will be under 0.5 ,ug/m3; but that some "hot spots" may have averages as high as 6 [Lg/m3.1 An EEC directive proposes that long-term average concentrations, away from traffic, up to 2 ,ug/m3 are acceptable.The lead concentration quicd.
A man who insisted on having his hat taken off by the staff of his residential home after hours at the day hospital doing things for himself illustrates one of the challenges of geriatric rehabilitation: someone may be encouraged to do more than he Physiotherapists and occupational therapists are obvious essentials for many elderly people in hospital; but a national study of resources in geriatric medicine has shown that numbers of both are quite inadequate and not likely to become adequate.'0 A special grade of rehabilitation nurse has been recommended for staffing wards needing a strong element of rehabilitation.'0 Gradual withdrawal of nursing support is part of good rehabilitation and nurses, it is emphasised, should always encourage self help and activities taught by therapists.
After one of the noisiest nights I have ever spent, one morning in 1957 I saw banners being raised over the streets of Zurich bearing the words "Die riihige Stadt hat wenige kranken." But whether "the quiet city does have few ill people"-or the noisy one many sick-is harder to prove than the effects of noise on hearing.The damage to hearing caused by intense noise has microscopically visible effects on the inner ear and is related to the intensity, nature, and duration of the noise. DAPHNE GLOAG, MA, staff editor much higher peaks.7 Some 10-12% of attenders had noisy jobs. On the basis of the data on attendance about 1500 out of an estimated 6 million disco attenders, it is calculated, will develop a permanent hearing loss sufficient to interfere with conversation, and more a higher-frequency loss. The Noise Advisory Council recommends that a code of practice should be drawn up and the possible risks made known to attenders.Since susceptibility to damage varies, a predictive test would be useful-possibly based on the temporary change in the threshold of hearing (threshold shift) caused by auditory fatigue after intense noise; but no reliable method has so far emerged.' Brown eyes appear to be associated with greater resistance to auditory fatigue than blue eyes.8 Some evidence that the permanent hearing threshold might be more affected by noise in blue-eyed people has appeared recently" and is being followed up. There is no proof of cause and effect; since melanin in the cochlea might be protective8 the idea is interesting, but should be treated with caution.If intense noise can cause appreciable hearing loss, can moderate noise cause a modest loss-and should we try to cut Measuring noise Noise is usually measured in decibels (dB) on a logarithmic scale expressing the ratios of particular sound pressures to a reference level (0 dB). A doubling of sound pressure is an mcrease of about 6 dB; but subjectively an increase of 10 dB, on average, makes a sound twice as loud.' The commonly used A scale (dB(A)) incorporates a weighting to take account of the ear's varying responses to sounds of different frequencies. There are many noise indices, including dB(A) Lq (the continuous equivalent sound level or average over a given period) and dB(A) L.. (the peak level).
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