Lead poisoning and lead absorption

by Sir Thomas Morison Legge; Kenneth Weldon Goadby

Danger and Prevention.

—Duckering has shown (see [p. 203]) that fumes of chloride of lead are given off which are especially noticeable when the dipped article is removed to a stand to have the superfluous metal wiped from it with tow while still in a molten state. Detailed reference is made on [p. 204] to the nature of the fume given off and the amount of lead present in the atmosphere breathed and inhaled daily by the worker.

The danger from fumes can be in great measure removed, both from the bath and from the wiping stand, by locally applied exhaust ventilation, which may be secured by utilization of the draught from the fire under each melting-pot, or by a hood and duct carried vertically through the roof if arranged as described on [p. 209]. Danger from dust arises also from the skimmings, if not deposited in a receptacle within the hood, from dust and débris on the floor, and possibly from traces of metallic lead and lead chloride attached to particles of tow floating in the air. Risk of lead absorption is less in later processes, such as affixing the spout and handle (mounting), and hammering or denting. Occasionally roughnesses are removed by rubbing the coating with emery paper.

Harness Furniture.

—Hames, buckles, bits, etc., are usually coated with nickel or copper, more rarely with silver. The process is in the nature of soldering, and the steel, prepared in the same way as has been described for hollow-ware, has a mixture of two parts tin and one part lead poured over it on a hearth. The strip of thin nickel sheeting is passed through a similar mixture, and is wiped with tow—the operation to which such poisoning as occurs in this industry is mainly due, in consequence of the difficulty of efficiently removing the vapour of lead chloride from the molten metal upon the long strip of nickel. Subsequently the prepared steel article and the strip of nickel or copper are made to unite under pressure of a soldering-iron. In silver plating danger from fume is slightly less, as the steel portion (for example, the hame) only is tinned. In the final operation of polishing on a mop danger arises from dust, unless locally applied exhaust is provided.

Iron Drums and Kegs.

—Use of a tinning mixture of lead and tin in this industry is obviously in the nature of soldering. The body of the drum is made either of black sheet-iron or of terne (lead-coated) sheet. In order to unite the seam and to fix the bottom sheet, the drum is made to stand in a shallow bath and laid on its side. The danger from lead chloride vapour is considerable, and the method of prevention is precisely of the kind described above.

Similar coating of articles first cleaned in hydrochloric acid is met with, as, for example, of the component parts of radiators of motor-cars, of steel bars, and of wire. Incidence of poisoning has not occurred to an extent to make necessary more than the application of locally-applied exhaust to remove the fumes.

Manufacture of Terne Plates.

—The manufacture of lead-coated sheets for roofing purposes is carried on in a few works in South Wales along with the manufacture of tin plates. Lead poisoning in the industry is practically unknown. We can only recollect occurrence of one case, despite the fact that the mixture contains from 65 to 95 per cent. of lead. For cleaning the plates prior to passing them through the concentrated zinc chloride flux into the molten mixture, dilute sulphuric acid is used, and not hydrochloric acid. As to the remarkably different results on health of the two processes, Duckering concludes: