Lead poisoning and lead absorption

by Sir Thomas Morison Legge; Kenneth Weldon Goadby

In these experiments acetate was given in one case only, and then in the form of pills coated with keratin. It is impossible to say, however, whether the animal ever received any soluble lead, as on one or two occasions the keratin pills passed right through the animal without dissolving. On the other hand, feeding with nitrate of lead in water produced symptoms, but when the nitrate was given in milk no symptoms appeared. It will be noticed it took a cat four months to show any signs of poisoning taking 0·1 gramme per day; whereas the animal receiving subcutaneous doses of 0·16 gramme of acetate showed paralysis in fifteen days, and in twenty-two days was so ill that it had to be destroyed under an anæsthetic. The same relationship in time also obtains in the case of the animals fed on dry white lead. In practically no instance did definite or severe poisoning follow the feeding on dry white lead alone, even when quite large quantities were taken. On reference to the inoculation experiments of [Table XI.], it will be seen that the inoculation of 2 grammes of dry white lead produced definite symptoms, although the feeding cats had an amount very largely in excess of this. The only animals fed on white lead or frit exhibiting signs of lead poisoning were those which were given alcohol in addition to the lead compound.

A comparison of the results given in [Tables XI.] and [XII.] shows that animals which received lead compounds subcutaneously suffered much more than the animals which received the lead via the gastro-intestinal canal, even when the doses given via the mouth were exceedingly large. It will follow, then, that the actual contact with the more intimate fluids of the body, rather than the digestive juices, determines the solubility and general distribution of the lead compound in the body. This is confirmed by a recent paper by Straub[6].

The animals experimented upon by feeding were kept in the laboratory under the same conditions as the inhalation animals, but were so placed that under no circumstance could they obtain any lead dust by inhalation. These animals were used as control to the breathing experiments, the substance fed to the animals being in all cases the same substance as was used for the various inhalation experiments; but in addition a certain number of the animals were given alcohol, which are referred to in [Table XII.] Alcohol was also given to animal No. 6 in the inhalation series.

The animals fed with lead were fed with the same compound which was used for the inhalation experiments, 0·4 to 1 gramme being given daily; so that during the period these animals were exposed to lead dust the other animals were taking the same compound via the intestinal canal, but in much larger quantities, and yet they exhibited no signs of lead poisoning.

TABLE XI.—INOCULATION.

No. of Animal.	Weight.	Total Compound used and Quantity.	Number of Inoculations.	Date of First Symptoms.	Duration.	Result.	Final Weight.
	Kgs.						Kgs.
16	3·200	0·91 grm. lead acetate: (1) 0·16; (2) 0·5; (3) 0·25	3	Forty-fifth day encephalopathy	47 days	Died	1·750
25	3·350	Fritted lead: (1) 0·6; (2) 2·0 = 2·6 grms.	2	Twenty-sixth day slight paralysis of left hind-limb	26 days	Killed	3·200
28	3·050	2 grms. white lead	1	Fourth day aborted	23 days	Died	Weight not affected
31	3·450	0·35 grm. white lead	—	No symptoms	1 year	Recovered	3·300
32	2·900	0·3 grm. frit	1	Eleventh day stiff joint; stepping not normal	28 days	Paralysis; died	2·400
33	3·150	0·16 grm. PbO as acetate	1	Fifteenth day paralysis	22 days	Paralysis; killed	2·150
35	3·750	2·0 grms. water-washed frit	1	Ninth day aborted	1 year	Recovered, but thin	2·900
40	3·050	1·0 grm. unwashed frit	1	Forty-seventh day some muscular weakness	58 days	Died	2·250
41	3·000	1·0 grm. acetic acid and water-washed frit	1	No symptoms	5 months	Recovered	2·900
42	2·800	1·0 grm. water-washed frit	1	No symptoms	4 months	Recovered	2·950
43	2·900	Lead nitrate in water: 0·01 grm. per diem	—	Thirtieth day encephalopathy	5 months	Died	2·100

TABLE XII.—FEEDING EXPERIMENTS.

No. of Animal.	Weight.	Compound of Pb used.	Other Substance.	First Appearance of Poisoning Symptoms.	Total Duration of Experiment.	Result.	Final Weight.
	Kgs.						Kgs.
2	2·750	0·5 to 0·1 grm. flue dust (55 per cent. PbO) from blast-furnace flue	None	Vomited fifth day; no other symptoms	2 months	Recovered	2·000
9a	3·500	0·5 grm. dry white lead	None	Vomited fifth day; no other symptoms	2 months	—	3·350
11a	3·850	0·8 grm.	None	None	8 months	—	3·900
	3·900	After 8 months given alcohol	50 c.c. alcohol (port wine)	1 month	2 months	Died (encephalopathy)	1·500
12	3·800	0·8 grm. dry white lead	50 c.c. port wine	1 month slight paralysis	38 days	Died (encephalopathy)	2·250
13	3·400	0·8 grm. dry white lead	None	None	18 months	Recovered	2·950
14	3·650	0·4 grm. low-solubility frit	None	None	8 months	Given port wine	3·750
	3·730	0·4 grm. low-solubility frit and alcohol	50 c.c. port wine	6 months encephalopathy	1 year	Died cerebral symptoms	2·600
23	4·100	1 grm. high-solubility glaze	None	None	1 year	No symptoms	4·600
	4·600	Given lead nitrate, 0·01 to 0·1 grm.	None	None	5 months	No symptoms except loss of weight	3·450
24	2·900	1 grm. high-solubility glaze	None	None	6 months	Recovered	4·350
46	2·150	0·1 grm. lead nitrate in water	None	4 months opisthotonus	4 months	Died cerebral symptoms	3·200
47	2·100	0·1 grm. lead nitrate in milk	None	None	4 months	Recovered[A]	2·900
49	2·500	2 grs. acetate in keratin pill	None	None	3 months	Recovered[A]	2·650
15	2·950	Control no lead	None	None	1 year	No symptoms due to confinement in cage	3·100

[A] Increased in weight.

TABLE XIII.—INHALATION EXPERIMENTS.