Dust, endotoxin, fungi, and bacteria exposure as determined by work task, season, and type of plant in a flower greenhouse

T. Thilsing, A. M. Madsen, I. Basinas, V. Schlunssen, K. Tendal, J. Baelum

Research output: Contribution to journalJournal articleResearchpeer-review


BACKGROUND: Greenhouse workers are exposed to dust, endotoxin, fungi, and bacteria potentially causing airway inflammation as well as systemic symptoms. Knowledge about determinants of exposure is a prerequisite for efficient prevention through knowledge-based reduction in exposure. The objective of this study was to assess the occupational exposure in a flower greenhouse and to investigate the impact of work tasks on the intensity and variability in exposure. METHODS: Seventy-six personal full-shift exposure measurements were performed on 38 employees in a Danish flower greenhouse producing Campanula, Lavandula, Rhipsalideae, and Helleborus. The samples were gravimetrically analysed for inhalable dust. Endotoxin was assessed by the Limulus Amoebocyte Lysate test and culture-based quantification of bacteria and fungi was performed. Information on the performed tasks during sampling was extracted from the greenhouse electronic task logging system. Associations between log-transformed exposure outcomes, season, and work tasks were examined in linear mixed-effects regression with worker identity as random effect. RESULTS: Measured concentrations ranged between 0.04 and 2.41mg m(-3) for inhalable dust and between 0.84 and 1097 EU m(-3) for endotoxin exposure, with the highest mean levels measured during Lavandula and Campanula handling, respectively. Personal exposure to fungi ranged between 1.8x10(2) and 3.4x10(6) colony-forming units (CFU) m(-3) and to bacteria between 1.6x10(1) and 4.2x10(5) CFU m(-3). Exposure to dust, endotoxin, fungi, and bacteria differed between seasons. Packing Lavandula, sticking, potting, and grading Rhipsalideae, and all examined tasks related to Campanula production except sticking increased dust exposure. Endotoxin exposure was increased during sticking Campanula and pinching or packing Rhipsalideae, and fungi exposure was elevated by subtasks performed in the research and development area for Campanula, and by potting, packing/dumping Campanula. Sticking and working with subtasks in the research and development area for Campanula increased bacteria exposure. CONCLUSION: This study revealed moderate dust exposure levels compared to the levels observed in other greenhouse productions and other occupations with organic dust exposure such as farming. However, high exposures to bacteria and fungi were detected during selected tasks and the proposed health-based endotoxin exposure limit of 90 EU m(-3) was exceeded in 30% of the samples, which may have health implications for the employees. Exposure levels were found to vary depending on the tasks performed, and thereby results can be used to direct task-based initiatives to reduce workplace exposures.
Original languageEnglish
JournalAnnals of Occupational Hygiene
Issue number2
Pages (from-to)142-157
Publication statusPublished - Mar 2015


  • Bacteria
  • Dust
  • Endotoxin
  • Exposure
  • Flower greenhouse
  • Fungi
  • Work task
  • Fungi/isolation & purification
  • Plants/microbiology
  • Humans
  • Occupational Exposure
  • Male
  • Environmental Monitoring/instrumentation
  • Flowers
  • Bacteria/isolation & purification
  • Air Pollutants, Occupational/analysis
  • Endotoxins/analysis
  • Inhalation Exposure/analysis
  • Female
  • Agriculture/methods
  • Dust/analysis
  • Seasons
  • Task Performance and Analysis

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