5.1 Fungicides

The term fungicide, as used in this study is limited to those biocides in a liquid medium applied directly to the surface of an affected item. The application may be intended either to prevent the growth of mold, or to kill the mold once growth has begun. Of the fungicides recommended in the literature, most have proved ineffective in terms of long term protection or deleterious to the materials themselves. Those which do seem to have some level of residual toxicity are now known to be hazardous to staff and users who may handle the materials later. Exposure may be by inhalation, ingestion, or adsorption through the skin. Warnings concerning the use of biocides should be rigorously adhered to, both with regard to the actual application and possible residual effects.

Beckwith, Swanson and Iliams conducted a comprehensive series of tests on biocides used a paper protectants and found that 28 commonly recommended fungicides were either ineffective in killing mold or damaging to paper. These included mercuric chloride, chloroform and formaldehyde.⁵ As recently as 1971, a British Museum pamphlet on biocides for archival and library materials recommended both chloroform and formaldehyde.⁶

Thymol and orthophenyl phenol crystals disolved in alcohol are often recommended as topical fungicides. Indeed, both have been widely used in the conservation field. Their use has been radically curtailed by recent studies showing that both can damage the eyes and upper respiratory system. Thymol is believed to be the more toxic of the two, affecting the liver, kidneys, central nervous system and the circulatory system as well.⁷

Of the fungicides recommended in the literature, only alcohol and orthophenyl phenol, at the strength commonly found in household cleaning products such as Lysol, are recommended for topical application and their use should be limited. Until more is known concerning the toxicity of orthophenyl phenol, the use of its crystalline form disolved in alcohol should be avoided. Any recommendations in the literature that are more than a few years old should be viewed with skepticism, since it is only in the last few years that the toxicity of a wide range of biocides has become a matter of concern. Research is still underway to establish precisely what levels of exposure may be acceptable.

It is a longstanding medical principle that one should treat the disease, not the symptom. The application of topical fungicides to items exhibiting mold growth is a classic example of treating the symptom, and fails to address the broader cause of the affliction. Items treated in this manner and returned to the same environment that produced the outbreak are very likely to develop recurring symptoms.