Hisamitsu Takai

A Single Exposure to Organic Dust of Non-Naïve Non-Exposed Volunteers Induces Long-Lasting Symptoms of Endotoxin Tolerance

Background: Work with occupational levels of organic dust is associated with a chronic inflammatory response that must somehow be controlled. Endotoxin tolerance has previously been described in vitro and animal studies as a mechanism that modifies the threshold at which response occurs. Objective: We investigated the response of non-naïve, currently non-exposed persons to a single exposure of organic dust in a swine confinement building. Methods: We exposed 16 non-naïve persons in a swine confinement building with low-to-moderate representative levels of organic dust and characterized their acute immune response. Results: Under work-like 3-hour exposure conditions, non-naïve volunteers developed an inflammatory response documented by an increase in interleukin-6 (IL-6) in bronchoalveolar lavage (BAL) from 3.1 to 6.1 pg/ml and visual indices of bronchial inflammation. Similarly, serum IL-6 increased with a peak 3 h after exposure. Tumor necrosis factor (TNF)-α was not detected in BAL, and serum TNF-α was reduced from 3.7 pg/ml at baseline to less than 2 pg/ml within 3 h after exposure, and remained decreased until 2 weeks after exposure. This is a cardinal marker for immune suppression which was confirmed by other markers: reduction in HLA-DR expression on alveolar macrophages and CD14 expression on blood monocytes. Conclusion: We report findings that suggest that long-lasting endotoxin tolerance and immune suppression may be induced by a brief exposure to organic dust concentrations in the medium-low range of occupational levels.

A COMPARISON STUDY OF DIFFERENT DUST CONTROL METHODS IN PIG BUILDINGS

The effects of different dust control methods and their combinations were studied in a pig finishing building with two identical rooms: a control room, and a treatment room. The methods involved in the study were addition of animal fat in feed, liquid feeding, spraying with water, and spraying with a mixture of rapeseed oil and water. The last mentioned method was used with and without an animal activity sensor to coordinate the time of spraying with the levels of animal activity. The combined method, spraying an oil-water mixture controlled by the animal activity sensor and adding animal fat to dry feed, reduced the airborne dust concentrations and dust exposures of herdsmen by about 80 and 85%, respectively. The optimum rate of oil spraying was found to be about 3.3 g oil day –1 pig –1 .

A Comparison between Temperature-Controlled Laminar Airflow Device and a Room Air-Cleaner in Reducing Exposure to Particles While Asleep

People spend approximately one third of their life sleeping. Exposure to pollutants in the sleep environment often leads to a variety of adverse health effects, such as development and exacerbation of asthma. Avoiding exposure to these pollutants by providing a sufficient air quality in the sleep environment might be a feasible method to alleviate these health symptoms. We performed full-scale laboratory measurements using a thermal manikin positioned on an experimental bed. Three ventilation settings were tested: with no filtration system operated, use of portable air cleaner and use of a temperature-controlled laminar airflow (TLA) device. The first part of the experiment investigated the air-flow characteristics in the breathing zone. In the second part, particle removal efficiency was estimated. Measured in the breathing zone, the room air cleaner demonstrated high turbulence intensity, high velocity and turbulence diffusivity level, with a particle reduction rate of 52% compared to baseline after 30 minutes. The TLA device delivered a laminar airflow to the breathing zone with a reduction rate of 99.5%. During a periodical duvet lifting mimicking a subject’s movement in bed, the particle concentration was significantly lower with the TLA device compared to the room air cleaner. The TLA device provided a barrier which significantly reduced the introduction of airborne particles into the breathing zone. Further studies should be conducted for the understanding of the transport of resuspended particles between the duvet and the laying body.

Inhalable dust and endotoxin exposure among Danish pig, dairy, poultry and mink farmers: results from the SUS cohort study

Objectives To provide information on variability and levels of personal dust and endotoxin exposure in different sectors of the primary animal production based on the same methodology. Methods 507 personal inhalable dust samples were collected from 327 Danish workers in 56 pig, 26 dairy, 4 mink and 3 poultry farms. Measurements in pig and dairy farmers were full-shift and performed during summer and winter. In contrast, poultry and mink farmers were monitored during four well-defined production stages. The sampled dust was analysed gravimetrically and its endotoxin content by the Limulus amebocyte lysate assay. Descriptive and random-effect regression analyses were used to summarize levels and variability in measured dust and endotoxin exposure concentrations. Results The overall geometric mean exposure was 2.5 mg/m3 (range < LOD-47.8) for dust and 992.3 EU/m3 (range < LOD-374 579) for endotoxin. Inhalable dust and endotoxin concentrations were highest among pig and poultry farmers, and lowest among dairy and mink farmers, respectively. Exposure among pig and cattle farmers was characterised by a large day-to-day variability that increased from indoor to outdoor working environment. Only mink farmers could meet the Danish occupational exposure limit for total dust (3 mg/m3); the recently proposed Dutch exposure-limit for endotoxin (90 EU/m3) was exceeded by more than 93% of our measurements. Conclusions Danish animal farmers are exposed to levels of dust and endotoxin exposure potentially hazardous for their respiratory health. The development of exposure reduction strategies will require in-depth knowledge of factors affecting day-to-day variability in exposure.