Biological activities of respirable dust from Eastern Canadian peat moss factories.

Bacteria, moulds, endotoxin and quartz from respirable dust of agricultural and industrial buildings are typically incriminated for the respiratory health decline of exposed workers despite that dust being an undefined mixture and quantification methods of aerosolized bacteria, moulds or endotoxin not being standardized yet. We developed an in vitro alveolar epithelial cell system in which biological activities of peat moss factories' dust might be correlated to bacteria, mould, endotoxin and quartz concentrations of the analyzed samples. Following exposure, interleukin-8 protein secretion, necrosis and apoptosis of the exposed A549 cells were monitored respectively with ELISA on cell supernatants, trypan blue exclusion and DNA fragmentation detection by flow cytometry. Respirable dust was collected with liquid impingers and respirable quartz with 10mm Dorr-Oliver cyclones. We quantified mesophilic bacteria, mesophilic moulds and endotoxins from liquid impinger samples. No correlation was observed between biological activities of dust and bacteria, mould, endotoxin or quartz concentrations under our experimental conditions. Our speculation is that simple measurements, such as dust concentrations, may not be adequate indicators of the human respiratory health hazard for a given environment.

Bioaerosols in peat moss processing plants.

Peat moss is organic matter colonized by large numbers of microorganisms. Storage prior to its processing may result in massive microbial growth. These biological contaminants can become airborne during processing. Our goals were (a) to evaluate concentrations of bioaerosols (inhalable dust, molds, bacteria) in peat moss processing plants that used dust removing systems, and (b) to evaluate the presence of these microorganisms in peat moss. Fourteen plants from Eastern Canada were visited; 3 plants operated all year (all-year mixing plants), and 11 plants functioned only during summer months (seasonal). Air samples were taken throughout the day at different work sites using IOM cassettes for inhalable dust and All-Glass Impinger-30 samplers and Andersen six-stage impactors for microorganisms. Samples of nonprocessed and bagged peat moss (solid material) were also taken and analyzed. A total of 25 work sites for air sampling and 33 solid material samples were analyzed. Air samples contained up to 441.7 mg/m3 of inhalable dust and up to 1.0 x 10(8) CFU/m3 mesophilic molds and 3.3 x 10(5) CFU/m3 bacteria. Seasonal plants were more contaminated with molds and dust than all-year mixing plants. Sieving sites were the most highly contaminated work sites. Airborne dust concentration was significantly correlated with molds and bacteria. Up to 3.8 x 10(7) CFU/g (dry weight) and 4.8 x 10(7) CFU/g (dry weight) molds and bacteria, respectively, were found in the solid material samples. Airborne contaminants did not correlate with solid material content. Despite the use of dust removing systems, peat moss processing plants contain very large amounts of microbially contaminated bioaerosols that do not correlate with the quality of the processed peat. Efficiency of dust removing systems could influence the contamination levels.

Cross-sensitivities of electrochemical detectors used to monitor worker exposures to airborne contaminants: false positive responses in the absence of target analytes.

Ideally, the response of electrochemical detectors is proportional to the concentration of targeted airborne chemicals and is not be affected by concomitantly present substances. Manufacturers provide a limited list of cross-sensitivities but end-users have anecdotally reported unexpected interferences by other substances. Electrochemical detectors designed to measure airborne levels of CO, H(2)S, NO, NO(2), or SO(2), were challenged with potentially interfering substances in the absence of target analytes. Cross-sensitivities undocumented by the manufacturers were observed and were found to vary between different models of instruments for the same challenge chemical.

Investigation of determinants of past and current exposures to formaldehyde in the reconstituted wood panel industry in Quebec.

OBJECTIVES: Past and present formaldehyde measurements made in facilities manufacturing reconstituted wood panels in Quebec have been collected in order to assess formaldehyde exposure and its determinants in this industry. METHODS: All 12 plants manufacturing Oriented-strand board (OSB), Medium density fibreboard (MDF) and Particle board (PB) in Quebec were visited by a research team which took area and personal measurements. Past measurements taken by governmental occupational health teams in these plants were also collected. Log-transformed formaldehyde concentrations were analysed with extended linear mixed-effects models. RESULTS: During 2001-2002, 275 measurements were taken by the research team, while 590 measurements dating back to 1984 were collected from governmental files. The area measurements had a global geometric mean (GM) of 0.28 p.p.m. [geometric standard deviation (GSD): 3.1]. The GM of the personal measurements was 0.17 p.p.m. (GSD: 2.3). The fixed-effects of the models for personal and area measurements explained 61 and 57% of the variance, respectively. Job (working area for area concentrations), process (PB, MDF, OSB), season of sampling, origin of the data (research, governmental) and year of sampling were significant determinants of exposure. Proximity to the press, winter conditions, PB and MDF processes and governmental data resulted in the highest exposures. Significant within-sampling campaign correlation was found for both personal and area models. The final models include different residual variances by process for personal measurements and by working area for area measurements. CONCLUSIONS: Several determinants of exposure to formaldehyde in the reconstituted wood panel industry were successfully identified. Higher levels found in governmental data as compared to research data may be explained by a 'worst-case' strategy bias. The observed intra-sampling campaign correlation supports existing results suggesting that measurements taken in a small time frame tend to be correlated. Exposures in this sector are low compared to most 8 h-TWA occupational exposure limits (e.g. 1 p.p.m.) but close to the most demanding ones (e.g. 0.3 p.p.m.).