Patent ID: 7147824

Claim:
A method for reducing a risk that a person in a metalworking environment will contract hypersensitivity pneumonitis caused by Mycobacterium immunogenum which is present in the environment, which comprises: (a) providing a composition comprising a copper complex comprising disodium monocopper (II) citrate and an isothiazolone mixture wherein the copper complex provides more than about 250 ppm of copper ion to a metalworking fluid, wherein the isothiazolone mixture comprises 5-chloro-2methyl-4 -isothiazolin-3-one and 2-methyl-4 -isothiazolin-3-one, wherein the isothiazolone mixture is present in an amount which is less than is required for biocidal activity when the mixture is introduced into the metalworkinq fluid alone; (b) adding the composition to the metalworking fluid, which contains components from use of the fluid which interfere with the antimicrobial activity of the isothiazolone mixture in the environment, in an amount which is sufficient to suppress the growth of the Mycobacterium immunogenum in the metalworking fluid for at least 48 hours wherein the metalworking fluid containing the composition is monitored for the Mycobacterium immunogenum ; and (c) exposing the person to the metalworking environment, wherein suppression of the growth of the Mycobacterium immunogenum in the metalworking fluid by the composition reduces the risk that the person will contract the hypersensitivity pneumonitis.