Handbook of preventive medicine.

  • Great Britain. Air Ministry.
Date:
1959
Catalogue details

Licence: Public Domain Mark

Credit: Handbook of preventive medicine. Source: Wellcome Collection.

    421/556 (page 357)
    129. Prevention. The routine precautions against the inhalation of dust and fume are essential. In particular lead should not be used if there is a practicable substitute for it, and there must be close medical supervision of those working with lead and its compounds. They should be medically examined: quarterly (or more frequently if there is a statutory require- ment), when a blood count, including a punctate count, should be carried out. Adequate arrangements are necessary for washing and changing facilities as well as for protective clothing. There are numerous statutory regulations governing work in which lead is a risk; these are contained in Factory Orders, published by H.M.S.O. 130. Toxic Concentration. The maximum allowable concentration (M.A.C.) of lead in the atmosphere is 0-15 mgm. per cubic metre. MERCURY 131. Properties. Mercury (Hg) is a silvery mobile liquid. It forms mer-. curic and mercurous inorganic salts and various mercurial organic com- pounds. Most metals dissolve readily in or amalgamate with mercury, which vapourizes at room temperature. In air saturated. with mercury there-is 1-84 ppm at 20°C. and 8-5 ppm at 40°C. The rate at which saturation is reached depends on temperature, pressure, the area of the surface of mercury exposed, and the rate of air exchange. The atomic weight is 200-61; boiling point is 357°C. and freezing point —39°C, Soluble mercury salts are violent corrosives. 132. Uses and Occurrence. Mercury is used in electrical apparatus, the manufacture of scientific instruments, in pharmacy and chemistry. It is a constituent of explosives, antifouling paint and, in organic forms, of agricultural fungicides. Mercury became notorious, as an industrial poison, in the silvering of mirrors by the old amalgam process and in the carrotting of fur in the hat trade (hence “‘mad as a hatter’’). 133. Absorption and Effects. Absorption in industry is by inhalation of dust or fume, but mercury can be absorbed through the skin and thera- peutic poisoning by this means or by ingestion have occurred. Industrial poisoning is typically chronic and affects the nervous system mainly. Mercury fulminate causes dermatitis. Organic mercurials cause specific irreversible degeneration of the posterior column of the spinal cord, of its occipital continuation, and of the cerebellum. 134. Signs and Symptoms. Inorganic mercury intoxication takes the form of salivation, stomatitis, loss of teeth and cachexia, with mercurial erethism. The latter consists of intention tremor, nervous shyness and shrinking, loss of confidence, vague fears, and inability to perform a task under observation. There is irritability, drowsiness, insomnia, apathy, and amnesia, with at times outbursts of anger on trifling provocation. The gait may be unsteady. There is some resemblance to chronic encep- halitic parkinsonism. Intoxication by organic mercurial compounds causes ataxia, dysarthria, muscular inco-ordination, and optic atrophy with gross constriction of the visual fields; there are no mental changes. Fulminate dermatitis is severe and accompanied by conjunctivitis, blepharitis, and inflammation of nose and throat. Punched-out ulcers or *“*holes”’ occur if particles of fulminate become lodged in abrasions or cracks on the skin. 135. Prevention. Prevention consists of all measures to protect workers against fume and dust. There should be periodic medica] examinations