The possibility that pesticides may be present in museum collections has been known for some time. Many of these compounds are toxic, and can be dangerous to individuals who come in contact with them. It is therefore important to identify and understand all pesticide residues that may be present in natural history specimens as well as objects in anthropological and ethnographic collections.

The identification of pesticides is particularly important for objects that are being repatriated to Aboriginal communities and individuals. Such items (e.g. masks and other sacred artifacts) will often be used in ways that bring them into greater contact with people than had previously been the case. These changes in usage can substantially increase the inherent risks of any toxic materials that might be present.

X-radiograph of a natural history specimen (shrike) showing the presence of arsenic (evident as speckled white areas) in the bird‘s skin.

Throughout the 19th and early-20th centuries, it was common practice for museums to apply arsenic or mercuric chloride solutions to natural history specimens as insecticides. Some museums used this treatment for ethnographic collections too. Other less publicized pesticides that have been identified in museum collections include naphthalene, paradichlorobenzene, dichlorovos, DDT, lindane, methyl bromide, lead arsenate, and borax. Unfortunately the application of these compounds was not necessarily recorded as part of an artifact's treatment history, and there may be no documentation in treatment dossiers. Collections must therefore be tested to determine whether or not pesticides are present.

CCI's Analytical Research Laboratory has been analysing artifacts to determine the presence of arsenic and mercury compounds since 1987; more than 850 natural history specimens and 450 artifacts in Canadian Aboriginal collections, as well as artifacts from other countries, have been examined. Investigations have recently begun on organic pesticides too, one example being a pilot study of non-destructive methods (e.g. gas chromatography/mass spectrometry to analyse vapours from volatile organic pesticides) to detect naphthalene, paradichlorobenzene, and dichlorovos.

In addition to this type of research and analysis, the conservation community has recently held several seminars concerning the contamination of museum collections with pesticide residues. At the invitation of the organizers, CCI has participated in two of these: Contamination of Museum Materials and the Repatriation Process for California Indians: A Working Conference at San Francisco State University (September 29 – October 1, 2000) and Contaminated Collections: Preservation, Access and Use at the National Conservation Training Center in Shepherdstown, West Virginia (April 6–9, 2001), hosted by the Society for the Preservation of Natural History Collections, the National Park Service, and the Smithsonian National Museum of the American Indian. CCI's work on the analysis of museum objects for pesticide residues was presented at both of these meetings. At the Shepherdstown meeting CCI also participated in two working groups — one on Policy and Planning and one on Testing Protocols/Research and Development.

Researchers at CCI and other organizations are currently looking into some of the issues raised at both conferences: what pesticides may have been used in collections; methods to identify toxic materials present on the objects; the health effects of these materials on the people handling them; at what levels these materials pose a threat; proper handling and use protocols; and possible treatments to remove pesticides from artifacts.

Future work must proceed in a collaborative environment, and links with the Aboriginal communities, museums, occupational health officers, toxicologists, and other scientists are being pursued. By working together, both the artifacts and the individuals handling them can be protected from the dangers posed by pesticide residues.