5. Fungicides and fumigation
Most librarians, archivists and museum personnel share a conviction that mold must be killed. It is perhaps more appropriate and effective to concentrate on prevention, inhibition and removal. As noted earlier, molds are admirably equipped for survival. Even a kill ratio of 99% "is an almost insignificant loss to a fungus which can produce hundreds of thousands of spores in a small colony started from a single spore."1 Fungicides and fumigants broad ranging enough and powerful enough to achieve a 99% mortality for fungi are now known to be toxic to man as well. In considering the use of fungicides and fumigants for the prevention or treatment of mold growth, two basic facts should be kept in mind:
- All biocides are chemically reactive, i.e. they are capable of reacting with and altering materials to which they are applied.
- All biocides have some level of mammalian toxicity.2
The traditional chemical approach to biodeterioration involves two strategies. One strategy, fumigation, interferes with the vital activities of the organism. The other strategy, topical application of fungicides to an object, interferes with their consequences, that is with the chemical reactions of the organism and its substrate. The number of compounds in use today is fairly limited. They include certain metal derivatives, organic chemicals (of which the phenols are the most common), and certain organometal compounds.3 While there is a certain amount of interest in, and testing of more exotic techniques, including irradiation and the use of ozone, "we must not place too much reliance on the hope for brand-new biocidal agents as the solution to the problem."4 Both irradiation and ozone have been found to be damaging to certain materials.
It should be noted that the first strategy, interfering with the vital activities of the organism, can be accomplished without recourse to chemical treatment. Modification of the environmental factors required for the growth of mold is at least as effective as chemical treatments, and certainly far safer for both personnel and materials.