AN EVALUATION OF ORTHO-PHENYL PHENOL AS A FUNGICIDAL FUMIGANT FOR ARCHIVES AND LIBRARIES
John H. Haines, & Stuart A. Kohler
THE PROBLEMS CAUSED BY FUNGUS growth on books and paper are a major concern of archivists. Veritable disasters can be brought about when floods, leaking roofs, seeping walls or condensation bring moisture into archival collections. Fungus spores are ubiquitous in our atmosphere, both indoors and outdoors (Burge 1980); and the materials found in archives, such as paper, starch paste, hide glue, sizing leather and cloth are all suitable substrates for fungus growth. Enzymatic breakdown and discoloration from fungal growth inevitably result when moisture reaches books or paper.
No satisfactory cure for this condition has been effected, although many treatments have been tried. There are conflicting reports as to the potential damage to cellulosic materials in using gamma radiation at the intensity needed to be fungicidal (McCall 1983, Calvini 1979, Flores 1976). Impregnation of paper with solutions of fungicidal compounds is an effective deterrent to fungi, but would also be damaging to many archival materials.
Fumigation would seem to be a solution to the problem of killing the fungi without damaging the paper. Various fumigants have been used (Byers 1983, Strassberg 1978). Some effective fumigants have been demonstrated to be significant health hazards and to require special handling or permits. For this reason neither ethylene dibromide nor ethylene dichloride (in the form of Dowfume 75) are now considered safe for use in public buildings except with very special precautions and mechanical installation (Strassburg 1983).
It was decided to test o-phenylphenol because it has been effectively incorporated as a fungitoxic agent in paper for storing and protecting fruit and was considered less toxic than thymol (isopropyl-meta-cresol). Several authorities have recommended the substitution of OPP for thymol in every application (McComb in Nagin 1982). Thymol is described as “moderately hazardous” while OPP is described as “a slightly toxic irritant” (Strassburg 1978). The Merck Index (10th ed., 1983) lists OPP as having an LD50 orally in rats at 2.48 gr./kg and Thymol as having an LD50 orally in rats at 980 mg/kg. Thymol also has a strong odor which some people find objectionable.
The fungi chosen as test organisms are commonly found in indoor and outdoor air and represent a range of taxonomic groups, spore morphology, spore production and growth rates. They all grow well on paper and have noticeable pigments capable of discoloring paper.
The term “mold”, or its alternative spelling favored in Great Britain “mould”, does not refer to a classification within the fungi but is a term of convenience for the downy or furry growth form many fungi take when growing on an exposed surface. The term “fungus” will be used here as it is a definable and inclusive term for the organisms that make paper “moldy”.