Precautionary measures are necessary in the varnishing of woven materials, as the substances employed may contain volatile poisonous solvents. If these poisonous solvents cannot be replaced by others less poisonous, carefully applied exhaust ventilation must be provided. The same holds good when carbon bisulphide, benzene, and benzine are used as solvents in the production of woven materials impregnated with indiarubber.
Employment of lead salts and other poisonous metallic salts in the glossing of woven materials, or in order to render them non-inflammable, is to be deprecated.
Cases of lead poisoning have occurred in the working-up of asbestos, as lead wire is sometimes used in the process of weaving.
To protect workers in chlorine and sulphur bleaching from poisoning by chlorine or sulphur dioxide the gases arising from the bleaching liquids should be drawn away. Use of closed bleaching apparatus, as is the case in large works, reduces the danger to a minimum. Bleaching-rooms should be connected with a powerful stoneware fan, so that they may be thoroughly aired before they are entered.
Dye Works
Industrial poisoning by dyes is, in general, rare, as the natural dyes (wood and tar dyes) are almost without exception non-poisonous. Further, the dyes are generally only used in diluted solution. Formerly the arsenic in many tar dyes caused poisoning, but now it is usually the mordants which have harmful effect. To this class belong chromic acid salts and mordants containing arsenic, antimony (tartar-emetic), and also chloride of tin. In the scraping off of layers of paint containing arsenic, arsenic dust may arise. In Turkey red dyeworks, especially sodium arsenite is used for fixing the tar dyes.
Orpiment dyes which may give off poisonous arseniuretted hydrogen gas are becoming less and less used; from the point of view of industrial hygiene, the utmost possible avoidance of the use of arsenic-containing preparations in dye works is to be recommended. Where this is not possible, strict personal hygiene must be enforced (as, for instance, application of vaseline to the skin).
FOOTNOTES
[A] Leymann has dealt with the conditions of health in a large aniline factory in a later work which is referred to in detail in the section on the aniline industry.