A medical manufacturer is recalling the blood thinner heparin because it may be tainted with a potentially dangerous chemical.

B. Braun Medical's nationwide recall comes after heparin from a different manufacturer was linked to 19 deaths and hundreds of allergic reactions. Both manufacturers used the same supplier, Wisconsin-based Scientific Protein Laboratories, which owns a Chinese factory and buys from raw heparin from Chinese suppliers.

B. Braun Medical says the recall is a precaution and that no illnesses have been reported. The company started the recall after Scientific Protein Laboratories disclosed that an ingredient it provided contained a chemical that does not occur naturally.

Federal officials are investigating.

Heparin is derived from a mucus that coats pig intestines andother animal tissues.