960 7. MERCURIALS 



the kidneys (Berlin and Gibson, 1963). Less than 1% of the plasma Hg^"^ 

 is filtered, due to both protein binding and the fact that nearly 50% of the 

 Hg203 is in the erythrocytes and is slowly exchangeable with the plasma. 

 Thus much of the Hg^''^ found in the kidney tissue must come directly from 

 the blood since the glomerular filtration cannot account for it. In the case 

 of the mercurial diuretics, around 20-40% is excreted during the first day 

 (Borghgraef and Pitts, 1956; Calesnick et at., 1960), but progressively smaller 

 amounts are lost each day. The kidney retains appreciable mercurial for 

 many days; following injection of only 0.2 mg Hg/kg of HgClg into rats, the 

 renal level is around 12.4 //g/g at 52 days (Rothstein and Hayes, 1960), this 

 constituting 90% of the body mercury. MM is surprisingly well retained in 

 the kidney, at 32 days the level being only 30% reduced from that after 

 1 day (Swensson et al., 1959). It is obvious that cumulation invariably oc- 

 curs when a mercurial is administered daily. Indeed, HgClg given intrave- 

 nously every 21 days leads to a marked cumulation, the total body mercury 

 after 5 doses being twice that from a single dose (Rothstein and Hayes, 

 1960). Rats given HgClg subcutaneously daily cumulate mercury in several 

 tissues and require 2 weeks for the rates of intake and excretion to be equal 

 (Friberg, 1956). 



Normal human tissues contain mercury because there is a daily intake 

 in the food. Bread, flour, milk, pork, and beef contain 2-4 //g% mercury, 

 and certain vegetables a good deal more, depending on soil conditions and 

 sprays used (Szep, 1940). Forney and Harger (1949) reported a wide va- 

 riation in kidney mercury levels in normal human subjects (from to 12.7 

 mg% in 92 autopsies) with two thirds having concentrations greater than 

 0.1 mg%. Liver levels were less (from to 1.72 mg%) with values greater 

 than 0.1 mg% in one third. Those having received mercurial medication 

 ranged from 0.94 to 27.5 mg% mercury in the kidney. Similar results were 

 obtained by Griffith et al. (1954), the mean values in nonmercurialized cases 

 being 0.45 mg% in kidney, 0.10 mg% in liver, and 0.026 mg% in spleen 

 (these values are in terms of wet weight to compare with the results of 

 others, and were calculated from the dry weight figures with the data in 

 Table 1-8-3). Patients receiving large amounts of mercurials for some time 

 prior to death (mean of 4.7 g total) had much higher concentrations in the 

 kidney (3.4 mg%) and liver (0.36 mg%). It is very interesting that normal 

 human liver contains around 1 //g/g wet weight of mercury. From the values 

 for liver in Table 7-23 it is seen that in many cases the levels are lower even 

 though the animals had been given mercurials; since control concentrations 

 have seldom been obtained, it is questionable how much of the mercury in 

 most of the tissues is due to the administered mercurial and how much to 

 other sources. Of course, this does not apply to studies with Hg^*'^. It would 

 appear that human liver normally contains more mercury than the rodent 

 liver, but whether this is of dietary origin or a species difference is not known. 



