422 SALTS OF THE HEAVY METALS 



gastroenteritis, shown by nausea, vomiting, thirst and usually 

 diarrhea, although constipation may be seen. Death is usually pre- 

 ceded by coma, convulsions and collapse. 



Absorption. Lead salts are absorbed from- all surfaces of the 

 body, the skin as well as the digestive tract. There is no absolute 

 proof as to the form in which lead is absorbed but it is generally 

 believed to be absorbed as a soluble lead albuminate. 



Elimination. The salts of lead are largely eliminated as the 

 sulphide without undergoing absorption. The part which is ab- 

 sorbed is excreted by most channels of elimination, with the possible 

 exception of the sweat, although many believe it is excreted to some 

 extent in this secretion. The greater part is cast off by the epithelium 

 of the skin and digestive tract, although a considerable amount is 

 excreted in the urine. Potassium iodide will hasten its elimination 

 for a time but soon ceases to influence the process. Lead is often 

 deposited as the sulphide on the edge of the gums, giving the char- 

 acteristic " lead line." The part retained in the body soon disap- 

 pears from the blood and is largely stored in the liver and other 

 organs. 



The following table from Heubel was obtained by examination 

 of a dog killed with lead and gives some idea of the distribution of 

 lead in the body: 



Liver 0.03 — 10 per cent 



Kidney 0.03 —0.07 

 Brain 0.02 —0.05 



Bones 0.01 —0.04 



Muscles 0.004—0.008 

 Blood Traces. 



Toxicology. Lead poisoning may be conveniently divided into 

 the acute and chronic types. The acute is due to its corrosive ac- 

 tion before absorption, and the chronic, to its effects after absorp- 

 tion. 



There are numerous sources from which sufficient amounts of 

 lead may be obtained to cause poisoning. One of the most com- 

 mon is from lead pipes used for carrying drinking water. These 

 pipes are quite safe for hard water as they soon become crusted 

 over with insoluble lead sulphate! On the other hand, soft water, 

 especially, if it contains quantities of COg, easily dissolves enough 

 lead to produce chronic poisoning. A fairly safe method of deter- 

 mining the danger from this source is the examination of the inside 

 of the pipe. If the interior is found to be corroded and dull in 

 appearance there is little danger, while if it is bright, it indicates 

 that the lead is being dissolved. Other sources of lead are, the 

 vegetation in the vicinity of lead smelters, lead paints, scrapings 



