By Mariana Escamilla Martinez and Michelle Vergeer (Studio Redivivus)
As conservators we know that pests are one of the ten agents of deterioration. Pests, which might include vertebrates, such as rodents, or insect larvae, such as woodworm larvae, can produce major irreversible damage to cultural heritage objects. In recent years, health and safety concerns have led the conservation community to lessen the use of hazardous or toxic chemicals, many of which are included in pesticides. A great alternative to pesticides in controlling vermin is to implement preventive measures to avoid the pests from infesting objects in the first place. Nonetheless, when an artwork has already been infested, one of the safest and more environmentally friendly methods to eliminate these without causing stress to the artworks is the use of anoxic methods.
These methods work by reducing the oxygen percentage through exchange with gases such as helium, argon or nitrogen which is the one used most in our field. Other methods include the use of toxic concentrations of CO2 . Nitrogen, specifically, is readily available in the air we breathe. Our field regularly uses special devices designed to extract nitrogen from the air, injecting it into air-tight chambers. Pests are unable to survive prolonged containment in these anoxic environments.
Although other pest management options exist, the use of in-situ generated nitrogen has proven to be one of the most efficient methods. Various small businesses and museums in Europe and around the globe have invested in devices and bespoke set-ups that allow for such treatments in their facilities.
”The procedure is included in the European Standard EN16790:2016 Conservation of Cultural Heritage - Integrated pest management (IPM) for protection of cultural heritage. IPM is currently being used globally, it is more sustainable and reduces considerably the risks for the heritage objects and for the professionals dealing with them.“ ICOM EUROPE. Appeal on the ban of nitrogen. September 2019
In 2012 a new regulation was put in place which unfortunately affected the conservation field. The EU regulation 528/2012 (Biocidal Products Regulation) declared that only registered and therefore regulated products, such as ready-to-use canisters of nitrogen, are currently legal to be used. In-situ generated nitrogen is not a registered product and therefore, its use has become illegal. Unlike some misconceptions connecting this ban to the regulations set on the use of nitrogen for fertilizing purposes, this regulation was intended to create a more controlled use of biocidal products protecting users and the environment from detrimental health effects.
“With a view to achieving a high level of protection of human health, animal health and the environment, active substances with the worst hazard profiles should not be approved for use in biocidal products except in specific situations. These should include situations when approval is justified because of the negligible risk from exposure to the substance, human health, animal health or environmental reasons or the disproportionate negative impact for society of non-approval. When deciding if such active substances may be approved, the availability of suitable and sufficient alternative substances or technologies should also be considered. REGULATION (EU) No 528/2012
The regulation includes a requirement to obtain the mentioned canisters from licensed providers, of which only one exists in the EU. The increase in price for these treatments and the restricted availability of the nitrogen has reduced the ability to ensure the timely treatment of objects at risk. Furthermore, this decision hindered institutions and businesses that had already invested in such pest management methods, making use of their facilities nearly impossible.
“In summary, the nitrogen ban is not justified for health aspects – but only because of juridical and procedural reasons. It is a setback for the cultural heritage conservation community to have less choices for treatment interventions, with the anoxic treatment being among the most compatible with many materials and objects. Finally, the ban is also economically damaging the market of European stakeholders in the IPM business, favouring less sustainable and riskier treatments.“ Appeal on the ban of nitrogen for disinfection purposes in all of Europe ICOM EUROPE General Assembly, September 2019
ICOMOS and ICOM jointly published statements to call upon National Ministries, the European Parliament and Council to try to overturn this decree. Various joint statements and appeals to the conservation community in Europe to send letters and complaints to the European Commission reached discussions in Brussels.
“Therefore, ICOM and ICOMOS jointly call upon the National Ministries, the European Parliament and Council, to repeal as soon as possible the classification of nitrogen as a biocidal active substance across the European Union. We advocate for a solution in which the use of nitrogen for this specific purpose in cultural heritage preservation is ratified for the entire European Union.” ICOM/ICOMOS Joint Statement
Several European countries made use of article 55.3 of the Biocidal Products Regulation (BPR) to apply for a derogation for cultural heritage. The first application for a derogation was submitted by Austria in 2019. According to the process, affected parties should have the chance to submit arguments for and against the use of in-situ generated nitrogen. Thus, an open call was launched by the European Chemicals Agency (ECHA) in 2019 and was finalized in early 2020. The goal was to gather data on the use of nitrogen by conservation professionals and prove the lack of better alternatives.
The results were published online:
“In total 1487 comments were received (…). Citizens and organisations in 22 Member States sent comments, in different proportion (top 3: Germany (76%), Austria (6%), Spain (3%)). Contributions from respondents in EEA countries were also received: (Switzerland, Norway, Iceland) and also from individuals and organisations outside the EU and EEA (e.g. Georgia, Iran, Russia, Taiwan).”
614 comments were submitted on behalf of organisations of which 349 with an attachment. Almost 500 of the contributing organisations are museums, public libraries, archives or other cultural institutions. 80 comments were submitted on behalf of companies, most of them operating in the field of art conservation and restoration. Around 40 comments were submitted by national and international NGOs (mostly museum associations, associations of art restorers and conservators). All comments submitted on behalf of organisations except for 3, submitted by companies (…) were in favour of a derogation for products consisting of in-situ generated nitrogen.” ECHA, In-situ generated nitrogen-Summary Public Consultation. Article 55(3) of Regulation (EU) No 528/2012
Impressively, the international conservation community was clearly united and established a front to declare the ban as inacceptable for the preservation of cultural heritage.
In 2020 two amendments to the regulation were published in the Official Journal of the European Union (One in Portugal [July 2020. Amendment 2020/1047 EU] and the other put in place in the Netherlands [November 2020. Amendment 2020/1775/EU]). The published documents on these amendments clearly mention how the banning of in-situ generated nitrogen affects cultural heritage conservation methods related to pest management, and it also demonstrates how other available methods for treating pest-infested objects are not as efficient as the use of in-situ generated nitrogen; this method is currently still not approved for use in the EU. However, its use in the Netherlands is now tolerated within heritage conservation until 2024.
In the Netherlands the possibility to apply for an authorisation with a consortium of users is being assessed. This is supported by the Cultural Heritage Agency of the Netherlands and the Ministry of Education, Culture and Science. However, the EU still has to approve in-situ generated nitrogen as an active substance first. Once in-situ generated N2 is included in the Annex I list of the regulation, interested parties can apply for authorization of products using N2 with their national bodies.
Although this EU regulation is almost 10 years old, the first big steps towards the legal use of in-situ generated nitrogen in our field have just been made. We encourage you to ask in your regional conservation groups for related updates in your country.
Michelle Vergeer works as a painting conservator at Studio Redivivus in Den Haag. She graduated in 2015 from the master's programme in conservation at the University of Amsterdam and has worked for various museums and private conservation studios in the Netherlands and abroad.
Mariana Escamilla Martínez is a recent graduate of the Cologne Institute of Conservation Sciences (CICS). Her master’s thesis focused on the investigation of green solvents for their use on oil paintings. She is currently working as a paintings conservator at Studio Redivivus.
(Read the article in the June-July 2021 "News in Conservation" Issue 84, p. 12-15)