42nd Annual Meeting – Health and Safety Session, May 31, 2014, "Unintended Consequences of Persistant Residual Vapor-Phase Chemicals within Collection Storage" by Catharine Hawks and Kathyrn Makos

This talk, given in Saturday’s Health and Safety session, was a summary of a project at the Smithsonian’s National Museum of Natural History investigating the vapors that staff were exposed to when opening old storage cabinets.
Chemicals that accumulate from pest management or other treatments can be harmful to people, objects/specimens, and even storage furniture through inhalation, repeated exposure, and adsorbing or absorbing onto their surfaces. Many pesticides are particularly retained in lipids in specimens and in the wood components of storage cabinets – this has the potential to be problematic for those working with collections that were subjected to these types of treatments in the past, particularly natural history collections. The goals of the project were to detect, identify, and quantify concentrations of organic vapors in cabinets that were known to have held treated specimens, thereby being able to determine the level of risk. Entering into the project, mercury vapor was expected. Heavy metals and non-volatile particulates were not investigated, with the idea being that proper use of personal safety tools and regular cleaning with HEPA vacuums will negate their effect on humans.
Vapor data was collected via evacuated canisters using the USEPA TO-15 method, and a mercury vapor analyzer. Cabinets chosen for the survey were presumed to have not been opened recently (and some were known to have been left unopened for many years). Of the cabinets chosen, 55 held mammals, 100 held anthropological specimens, and 50 were empty but had held anthropological specimens in the past.
Contrary to expectations, none of the cabinets were found to have mercury vapor! However, 39 other volatile compounds were found. Thankfully, these compounds were only detected in the ppb levels, and all volatile compounds detected were well below (often 100-1000 times below) workplace exposure limits (TLV).
Data obtained was not significantly different from the empty and the filled cabinets, which suggests that empty cabinets retain some chemicals, even after long periods of time. However, measurements of volatile compounds present in storage outside of the cabinets were not taken.
Though these ranges are safe for humans, they may not be safe for collections stored within the cabinets or for the cabinets themselves. Two chemicals are of particular concern: PDB (1,4-dichlorobenzene) and naphthalene are both highly toxic and will be retained in fats and other proteinaceous materials. They also increase mobility of unsaturated fats and are likely carcinogenic. In addition, PDB may crystallize onto surfaces, leaving a reside that can be quite sticky and difficult to remove.
Due to the results of the survey, the authors have a few key recommendations for collections that may contain such chemicals:

  1. Improve storage: Budget towards accelerated disposal of old cabinets. Do not reuse them, even with non-collection items. Re-house collections in metal cabinets, and segregate treated specimens from the rest of the collection.
  2. Implement an integrated pest management system: This reduces the need for future treatments and can be non-toxic! Heat treatment is not recommended for pesticide-treated specimens.
  3. Implement safe work practices and practice personal safetey measures: Wear gloves, minimize case-browsing, examine objects in a well-ventilated area.
  4. Work towards remediation: place scavengers in cabinets that can’t be evaluated or dealt with now.
  5. Above all, be aware and be safe!