AIC's 42nd Annual Meeting

USEPA Method TO-15 monitoring, via specially-prepared evacuated canisters and analysis by gas chromatography/mass spectrometry, detected thirty-nine ambient volatile/semi-volatile organic compounds within several hundred collection storage cabinets at the National Museum of Natural History. Both empty and filled cases, with different pesticide treatment histories were selected, representing anthropology objects, vertebrate zoology specimens, photographs, collection documentation, and periodicals. All concentrations detected were in the parts per billion (ppb) range. Possible sources include both past treatment chemicals and structural/atmospheric agents: pesticides/fumigants; preparatory preservatives (ethanol, benzene, chlorinated degreasers); wood degradation; varnishes, paints, cleaners; freons; and halogenated and aromatic hydrocarbon byproducts.
Persistent residual vapor-phase chemicals, even at the ppb level, poses often unintended adverse effects, not only on the objects and specimens, and their users, but on the storage furniture itself. Some pesticides such as paradichlorobenzene (1,4-dichlorobenzene) and naphthalene re-crystallize on collections and storage equipment, resulting in a continual vapor equilibration within a cabinet and a potential inhalation exposure upon case opening. Both are classified as “reasonably anticipated to be a carcinogen” by the U.S. Dept. of Health and Human Services, National Toxicology Program. Organic chemicals penetrate and absorb into wooden storage furniture and paper-based storage supplies, and adsorb on metal, glass, and other non-absorptive materials. Data suggests that empty cases can be a detectable “sink” for these chemicals long after initial contamination. One type of collateral damage from these chemicals is a sticky residue that adheres insect carcasses and other frass onto the surfaces of storage furniture. This stubborn residue requires intensive post-treatment labor to remove from storage equipment, or if unsuccessful, results in expensive cabinet replacement.

The survey data warrant the need for a conservation science analysis of the detected chemicals to determine the most likely sources in order to develop targeted and efficient mitigation plans.

Responsible and sustainable collection care practices include a sound Integrated Pest Management (IPM) program with pro-active risk reduction to prevent infestations. Use of toxic chemical pesticides should be banned or severely restricted, as lasting residues not only impact life safety and collections, but also contribute to environmental pollution. Pest inspection, quarantine and treatment of incoming collections before they enter storage, and where warranted, measures such as freezing, heat treatments (with vapor capture filtration) and anoxia are activities well documented as to their efficacy in pest eradication.

A management-endorsed safety plan for preventing adverse human exposures to legacy chemicals would emphasize Chemical Hazard Communication, safe handling methods, HEPA-filtered vacuum cleaning of case interiors and workspaces, and minimizing exposures by removing objects to an examination table instead of working inside the opened cases. These measures also reflect good collection care practices.

Recommendations also include accelerated disposal of cases, particularly porous wooden cases, that house or formerly housed objects treated with hazardous chemicals, and segregated re-housing of treated objects from non-treated ones to prevent cross-contamination.