Am.  Tour.  Pharm. 
April,  1921. 
Manganese  as  a  Poison. 
283 
MANGANESE  AS  A  POISON  * 
The  toxicology  of  manganese  has  until  recently  been  little 
understood.  Used  therapeutically  as  potassium  permanganate 
essentially  for  external  application,  the  element  has  not  been  a 
cause  of  poisoning,  nor  have  the  small  quantities  that  occasionally 
find  internal  use  in  man  presented  toxicologic  problems.  Industrial 
workers  are  sometimes  exposed  to  the  dusts  of  ores  containing 
considerable  admixtures  of  manganese  compounds.  This  is  par- 
ticularly true  in  zinc  mines,  where  the  oxids  of  manganese,  iron 
and  zinc  occur  together.  Some  ores  also  have  a  high  content  of 
manganese  as  a  silicate.  As  the  sources  of  menace  are  insoluble 
dusts,  the  chief  portals  of  entry  into  the  body  must  be  the  aliment- 
ary canal  and  the  respiratory  tract.1  The  latter  is  commonly  borne 
in  mind  as  a  path  of  invasion  when  matter  in  particulate  form  is 
concerned.  The  possible  effects  of  coal  dust  on  the  lungs  of  the 
miner  and  of  quarry  dust  on  those  of  the  stone  cutter  are  widely 
appreciated  by  those  who  deal  with  industrial  menaces.  Less  con- 
sideration is  usually  given  to  the  equally  potent  danger  from 
swallowed  dusts.  In  the  case  of  the  latter  the  risk  depends  pri- 
marily on  their  solubility  in  the  alimentary  secretions.  Investiga- 
tions of  Reiman  and  Minot2  in  the  Laboratory  of  Applied  Physi- 
ology at  the  Harvard  Medical  School  demonstrate  that  ores 
containing  manganese  as  oxids  and  silicates  are  soluble  in  gastric 
juice.  Manganese  is  absorbed  in  the  blood  stream,  causing  in  most 
cases  a  slight  temporary  rise  in  manganese  concentration  followed 
by  a  quick  return  to  normal.  In  none  of  the  cases  studied  was  the 
manganese  content  of  the  blood  increased  by  the  ingestion  of  man- 
ganese ores  to  a  value  of  more  than  double  the  normal  level,  and 
in  some  of  the  subjects  no  increase  was  noted.  Even  prolonged 
feeding  of  large  amounts  of  manganese  ore  to  dogs  failed  to  pro- 
duce significant  changes  in  manganese  content  of  the  blood  and 
tissues  or  to  cause  any  pathologic  symptoms.  Manganese  ores  are 
thus  nontoxic,  and  in  order  to  produce  symptoms  of  poisoning 
*Jour.  Amer.  Med.  Assoc.,  76:  13  (March)  1921. 
"Edsall,  D.  L.;  Wilbur,  E.  P.,  and  Drinker,  C.  K. :  /.  Indust.  Hyg.  1 :  183 
(Aug.)  1919. 
2  Reiman,  C.  K.,  and  Minot,  A.  S. :  Absorption  and  Elimination  of  Man- 
ganese Ingested  as  Oxides  and  Silicates,  J.  Biol.  Ghent.  45  :  133  (Dec.)  1520. 
