A label indicating an insecticide solution has been applied to the binding of a book.
Within The National Archives’ collection, materials that may present a risk to those who access them are occasionally found.
These include:
- materials made from hazardous substances, such as insecticides, pigments, asbestos, and chemicals.
- materials with hazardous physical and/or chemical properties, such as cellulose nitrate film.
- physical materials, for example, sharp objects such as pins.
- biological materials, for example, plant matter.
Safe handling procedures are in place for known documents containing hazardous substances.
If you find objects or materials within the records that you suspect may be hazardous or present a risk, please notify a member of staff immediately. They will provide guidance on safe handling procedures.
Access to insecticide-affected records
In 2022, while reviewing documents from the FCO 141 record series for digitisation, The National Archives’ staff discovered labels indicating that these items had been treated with a “poisonous insecticidal solution.” Historical sources revealed that bookbinders in the early 20th century often used substances such as mercuric chloride, copper sulphate, and beechwood creosote. By the mid-20th century, these were likely replaced by organochlorine pesticides (OCPs) such as dichlorodiphenyltrichloroethane (DDT).
Scientific testing confirmed the presence of mercury and various hazardous compounds, including DDT, Lindane, Dieldrin, and pentachlorophenol (PCP), across all tested items regardless of format or creation period. To ensure safe access, occupational hygienists conducted air monitoring during production and handling. Results indicated no detectable risk of inhalation exposure while unable to assess risks associated with dermal transfer. Subsequent surface swabbing tests revealed that, while in very limited amount, pesticide residues can be transferred to staff and readers during handling of these documents.
Consequently, measures to minimise potential skin contact risks were implemented, including the use of gloves and other hygiene practices.
Building on this initial research, further investigation identified additional record series potentially treated with similar insecticides. To maintain public access while ensuring safety, we have adopted the same handling procedures for these collections as for FCO 141. A list of the potentially affected record series currently known to us can be found here.
Insect Enemies and Chemical Legacies: Reflections on Archival Practice by Haines and Angelova explores the historical use of pesticides in archival collections and their research has informed the list of potentially affected record series.
The identification of the insecticides used in treated records as well as the rational for their production and handling guidelines were published peer-reviewed research articles:
- Angelova, L. V., et al. (2023). “The use of ‘poisonous insecticidal solutions’ in bookbinding: coping with historic pesticide treatments in the archive.” Heritage Science 11(1): 51. https://doi.org/10.1186/s40494-023-00866-y
- Veall, M.-A., et al. (2025) “A Comparative Study of Invasive and Micro-Invasive Analytical Methods for the Detection and Identification of Historically Applied Pesticides to Archival Records.” Studies in Conservation: 1-12. https://doi.org/10.1080/00393630.2024.2429955
Safe handling procedures
To view records from these series, please adhere to the following guidelines:
- Advance ordering: Records must be ordered in advance and viewed in a designated room within the Reading Room.
- Glove use: Disposable nitrile gloves will be provided and must be worn while handling these documents.
- Device cleaning: Any devices (mobile phones, cameras, laptops) used while handling these records must be wiped down with the materials provided before leaving or after handling the documents.
- Hygiene precautions: Refrain from touching your face, eyes, or mouth during handling, and wash your hands thoroughly with soap upon completion.
We remain committed to further research and testing and will continue to monitor best practices to ensure safe access to historical records.