TOXICITY OF LITHIUM GREASE

Is "lithium grease" toxic to cattle?  A good question and one to stir the gray cells into action!  What is lithium grease?  Is tithi'um in the grease toxic?  What other con­tents in lithium grease could cause a disease problem?

A chemical dictionary describes lithium greases as greases using lithium soaps of the higher fatty acids as a base.  They are water resistant and are stable when heated above their melting point and cooled again.  They are used in aircraft and other low temperature service.  They are also in common use on farms as lubricants for machinery. Lithium hydroxystearate from hydrogenated castor oil is widely used.  (Rose's Condensed Chemical Dictionary, 7th edi­tion, 1966.)

Lithium carbonate (tablets or capsules) and lithium citrate (syrup) are used in human medi­cine to treat some mental con­ditions.  Preclinical studies have shown that lithium alters sodium transport in nerve and muscle cells and effects a shift toward intraneuronal me­tabolism of catecholamines. Lithium toxicity may develop in patients with significant renal or cardiovascular disease, se­vere debilitation or dehydra­tion, or sodium depletion. Toxic levels of lithium are close to therapeutic levels in humans (PDR, 1989).

The good news to the animal world is that lithium carbonate is not very. toxic.  The oral ld90 for rats is 710 mg/kg. Intravenous toxic doses to ani­mals are cardiotoxic, causing ECG changes, and in high doses may cause renal failure (Gosselin's Clinical Toxicology of Commercial Products:  Acute Poisoning, 5th ed., 1984).

So what about the toxicity of lithium grease in cattle?  I have not found any specific studies on the subject (they may exist), so I have to rely on conventional wisdom and say that it seems very unlikely that a cow could ingest enough lithium grease to cause a toxic response.  I would expect diarrhea to occur because of thegreasy nature of the substance and caution about the possibil­ity of inspiration (foreign body) pneumonia, similar to that sometimes seen in cattle following ingestion of waste oils and petroleum products.

It was suggested to me that lithium grease may contain mo­lybdenum, and again I know of no reports of molybdenum toxi­cosis (secondary hypocuprosis) in cattle due to ingestion of lithium grease.  Molybdenum toxicosis in cattle is seen clinically as a chronic toxico­sis characterized as fading of the haircoat(hypotrichromia), diarrhea and anemia.

If the reader is aware of specific information on the toxicity of lithium grease, I would appreciate a letter or telephone call to:

F.R. ROBINSON D.V.M.,PhD

CHIEF OF TOXICOLOGY
1175 ADDL
PURDUE UNIVERSITY
W. LAFAYETTE, IN 47907-1175

(795) 494-7449