Article Text

Original research
Occupational and environmental exposure to SARS-CoV-2 in and around infected mink farms
  1. Myrna M T de Rooij1,
  2. Renate W Hakze-Van der Honing2,
  3. Marcel M Hulst2,
  4. Frank Harders2,
  5. Marc Engelsma2,
  6. Wouter van de Hoef1,
  7. Kees Meliefste1,
  8. Sigrid Nieuwenweg1,
  9. Bas B Oude Munnink3,
  10. Isabella van Schothorst1,
  11. Reina S Sikkema3,
  12. Arco N van der Spek4,
  13. Marcel Spierenburg4,
  14. Jack Spithoven1,
  15. Ruth Bouwstra5,
  16. Robert-Jan Molenaar5,
  17. Marion Koopmans3,
  18. Arjan Stegeman6,
  19. Wim H M van der Poel2,
  20. Lidwien A M Smit1
  1. 1 Institute for Risk Assessment Sciences, Utrecht University, Utrecht, The Netherlands
  2. 2 Wageningen Bioveterinary Research, Lelystad, The Netherlands
  3. 3 Department of Viroscience, Erasmus MC, Rotterdam, The Netherlands
  4. 4 Netherlands Food and Consumer Product Safety Authority, Utrecht, The Netherlands
  5. 5 GD Animal Health, Deventer, The Netherlands
  6. 6 Farm Animal Health, Utrecht University, Utrecht, The Netherlands
  1. Correspondence to Dr Myrna M T de Rooij, Utrecht University Institute for Risk Assessment Sciences, Utrecht, The Netherlands; m.m.t.derooij{at}


Objective Unprecedented SARS-CoV-2 infections in farmed minks raised immediate concerns regarding transmission to humans and initiated intensive environmental investigations to assess occupational and environmental exposure.

Methods Air sampling was performed at infected Dutch mink farms, at farm premises and at nearby residential sites. A range of other environmental samples were collected from minks’ housing units, including bedding materials. SARS-CoV-2 RNA was analysed in all samples by quantitative PCR.

Results Inside the farms, considerable levels of SARS-CoV-2 RNA were found in airborne dust, especially in personal inhalable dust samples (approximately 1000–10 000 copies/m3). Most of the settling dust samples tested positive for SARS-CoV-2 RNA (82%, 75 of 92). SARS-CoV-2 RNA was not detected in outdoor air samples, except for those collected near the entrance of the most recently infected farm. Many samples of minks’ housing units and surfaces contained SARS-CoV-2 RNA.

Conclusions Infected mink farms can be highly contaminated with SARS-CoV-2 RNA. This warns of occupational exposure, which was substantiated by considerable SARS-CoV-2 RNA concentrations in personal air samples. Dispersion of SARS-CoV-2 to outdoor air was found to be limited and SARS-CoV-2 RNA was not detected in air samples collected beyond farm premises, implying a negligible risk of environmental exposure to nearby communities. Our occupational and environmental risk assessment is in line with whole genome sequencing analyses showing mink-to-human transmission among farm workers, but no indications of direct zoonotic transmission events to nearby communities.

  • environment
  • COVID-19
  • air pollution
  • farmers
  • viruses

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Data availability statement

All data relevant to the study are included in the article or uploaded as supplementary information.

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  • Contributors Conception and design: MMTdR, LAMS, BBOM, RS, AS, MS, RB, R-JM, MK, AS and WHMvdP. Data collection and laboratory work: MMTdR, RWH-VDH, MMH, FH, ME, WvdH, KM, SN, IvS, JS and LAMS. Data analyses and interpretation: MMTdR together with LAMS, with additional input from R-JM, MK, AS and WHMvdP. Preparation of the manuscript: MMTdR, together with LAMS, with additional input from RWH-VDH, MMH, FH, ME, WvdH, KM, SN, BBOM, IvS, RS, ANvdS, MS, JS, RB, R-JM, MK, AS and WHMvdP.

  • Funding This work was funded by the Netherlands Ministry of Agriculture, Nature and Foods.

  • Competing interests None declared.

  • Provenance and peer review Not commissioned; externally peer reviewed.

  • Supplemental material This content has been supplied by the author(s). It has not been vetted by BMJ Publishing Group Limited (BMJ) and may not have been peer-reviewed. Any opinions or recommendations discussed are solely those of the author(s) and are not endorsed by BMJ. BMJ disclaims all liability and responsibility arising from any reliance placed on the content. Where the content includes any translated material, BMJ does not warrant the accuracy and reliability of the translations (including but not limited to local regulations, clinical guidelines, terminology, drug names and drug dosages), and is not responsible for any error and/or omissions arising from translation and adaptation or otherwise.