The manufacture by the German process may be divided into three categories according to the degree of risk run:
1. The most dangerous processes are hanging the plates in the chambers, work at the filter press, drying, pulverising, and packing by hand.
2. Less dangerous are transport to the washer, washing, and grinding.
3. Relatively the least dangerous are casting the plates, transport of them to the chambers, drying, mechanical packing, and mixing with oil.
The number of cases of lead poisoning in white lead factories is often relatively great despite regulations. Casual labourers especially run the greatest risk. This is frequently brought out in the reports of the German factory inspectors, who connect the high proportion of cases directly with the large number of unskilled workers. Regulations are really only successful in factories with regular employment.
This has been found also in Great Britain, where the Medical Inspector of Factories showed that the cases among regular workers numbered 6 per cent. and among casual workers 39 per cent.
The following table gives particulars as to the occurrence of lead poisoning in the white lead factories in the district of Cologne in 1904, some of which have admirable hygienic arrangements:
+-----------+--------------+-----------------+---------------+--------+ | | | No. Employed. |Cases of Lead | | | | | |Poisoning. | | | | +-----------------+---------------+ No. of | | Place. | Manufacture. |Regular |Regular |Cases of| | | | |Casual | |Casual |Gastric | | | | | |Average | |Total|Catarrh.| +-----------+--------------+-----+-----+-----+----+----+-----+--------+ |Cologne I. | White lead { | 46 | 59 | 32 | 9 | 16 | 25 | 16 | | | { | 173 | 95 | 127 | 13 | 17 | 30 | 22 | | ” I. | Litharge and{ | 46 | 4 | 38 | 5 | 1 | 6 | 7 | | | red lead { | 76 | 62 | 49 | 3 | 4 | 7 | 15 | | | Chromate { | 14 | 2 | 11 | — | — | — | 5 | | | { | 43 | 72 | 33 | — | — | — | 7 | |Cologne II.| White lead, { | | | | | | | | | | litharge, { | 107 | 332 | 91 | 6 | 34 | 40 | 30 | | | and red lead{ | 102 | 332 | 76 | 9 | 19 | 28 | 38 | +-----------+--------------+-----+-----+-----+----+----+-----+--------+
It is worth noting that cases of lead poisoning have been reported in the manufacture of zinc white, as, for example, in Bohemia in 1907 and 1908.