Exposure to dust, endotoxins and microbes in Finnish vegetable greenhouses.

INTRODUCTION AND OBJECTIVE: In Finland and other northern countries, vegetable greenhouse workers are exposed to airborne dust and microbes all year round. The aim of the study was to assess respiratory exposure to dust, endotoxins and microbes, and to identify the risk phases of respiratory and skin exposure to promote safe working methods. MATERIAL AND METHODS: Work in greenhouses was observed and recorded in a structured form. 23 personal samples and eight stationary samples of dust, endotoxins and viable microbes were collected from eight tomato or cucumber greenhouses in Finland. Dust samples were analysed gravimetrically. Endotoxins were analysed on filters by chromogenic Limulus amoebocyte lysate assay. Microbes were collected on filters, incubated and counted in three different culture media. Eight additional stationary samples of microbes were collected on a six-phase impactor. RESULTS: The greenhouses were generally clean and well organised, but skin protection was deficient. The median of personal dust exposure was 0.24 mg/m3: 0.21 mg/m3 in the tomatohouses and 0.62 mg/m3 in the cucumber greenhouses. The mean level of bacteria in the tomato houses was 2.7 × 103 and in the cucumber houses 1.6×104. Those of fungi were 3.6 × 105 and 1.7 × 105 on Hagem and 8.1 × 105 and 1.9 × 105 on DG-18, respectively. The microbes made up about 1/10 of these values in the stationary samples. Very low concentrations of endotoxins were found in 5/23 air samples. CONCLUSIONS: The clean appearance of the greenhouses was reflected in the low to moderate levels of dust. Risk phases of high exposure, such as lifting leaf debris, were identified. The microbe species were typical of this climate, and their levels were comparable to other greenhouse studies, but lower than in farming. Prevention among the foreign workforce is challenging due to the lack of a common language.

High Prevalence of Sensitization to Mites and Insects in Greenhouses Using Biologic Pest Control.

BACKGROUND: Mites and insects are widely used as biologic pest control in greenhouses. A few studies have reported sensitization to mites among greenhouse workers, but the prevalence of sensitization to pest control insects is not known. OBJECTIVE: We aimed to determine the prevalence of IgE-mediated sensitization to pests and their control organisms in the population of exposed greenhouse workers and the relationship between sensitization and allergic symptoms. METHODS: In a cross-sectional study, we interviewed 117 tomato and cucumber greenhouse workers from eight companies that use biologic pest control. Sensitization to nine organisms was assessed by serum-specific IgE measurement. We also measured fractional exhaled nitric oxide. RESULTS: The prevalence of specific sensitization to pests and pest control organisms was 50%; to mites, 29%; and to insects, 46%. Of the individual species, Macrolophus pygmaeus insect sensitization had the highest prevalence (46%). Asthma symptoms were significantly associated with sensitization to pest and pest control organisms (odds ratio [OR] = 3.9; 95% confidence interval [CI], 1.2-12.5) and with a fractional exhaled nitric oxide level of 25 ppb or greater (OR = 4.8; 95% CI, 1.7-13.8), indicating eosinophilic airway inflammation. Southeast Asian origin was significantly associated with sensitization (OR = 5.1; 95% CI, 2.1-12.1) and rhinitis (OR = 2.8; 95% CI, 1.2-6.3). CONCLUSIONS: Tomato and cucumber greenhouse workers were commonly sensitized to predatory insect M pygmaeus and pest control mites. Our findings stress the importance of surveilling and preventing work-related allergic diseases among greenhouse workers.