Endotoxin and Hydrogen Sulphide Exposure and Effects on the Airways Among Waste Water Workers in Sewage Treatment Plants and Sewer Net System.

BACKGROUND: The purpose of this study is to investigate whether airborne exposure to endotoxins, hydrogen sulphide (H2S), and inhalable particles negatively impacts the respiratory system and inflammatory blood proteins in sewage plant and sewer net system workers and, further, to determine dose-response associations between exposure and health outcomes. METHODS: In total, 148 waste water workers (WWWs) from urban and rural sewage plants and the sewer net system participated. One hundred and twenty-one workers were exposed to sewage, 46 from sewage plants and 75 from the sewer net system. Twenty-seven workers were characterized as little or not exposed and served as an internal reference group. Personal inhalable samples were analysed for endotoxins (Limulus assay), particle dust (gravimetrically) and Salmonella and Yersinia spp. (polymerase chain reaction method, PCR). Levels of H2S were measured using personal electro chemical sensors. Intercellular adhesion molecule 1 (ICAM-1), interleukin 8 (IL-8), surfactant protein D (SP-D), club cell protein 16 (CC16), and macrophage inflammatory protein (MIP) were determined by enzyme-linked immunosorbent assay and C-reactive protein (CRP) by an HS-MicroCRP assay in blood samples. RESULTS: Workers in sewage plants were exposed to significantly higher levels of endotoxins compared to workers in the sewer net system [median 55 EU m-3 (4-262 EU m-3) and median 27 EU m-3 (1-304 EU m-3), respectively]. The estimated H2S index showed higher values when working in the sewer net system [median 3.1 (0.5-78.1)] compared to workers at the sewage plants [median 1.3 (0.5-9.3)], and the most excessive exposure was collecting sewage from cesspools (273 p.p.m.). No viable airborne Salmonella and Yersinia spp. were detected. The exposed workers had significantly higher CRP compared to the referents [1.2 µg ml-1 (0.1-19.0 µg ml-1) and 0.8 µg ml-1 (0.1-5.0 µg ml-1), respectively] and lower forced expiratory volume in 1 s (FEV1)% [92.6%, standard deviation (SD) 14.6 and 102.0%, SD 10.1, respectively], with numbers given as mean and SD. The serum concentration of CRP was significantly and negatively associated with FEV1% (ß = -7.7, R2 = 0.05) and forced vital capacity % (ß = -8.5, R2 = 0.08), and the serum concentration of ICAM-1 with the estimated exposure to H2S (ß = -19.9, R2 = 0.07). CONCLUSION: Despite moderate levels of endotoxin and H2S exposure, the results indicate an impact of these agents on lung function and the adhesion molecule ICAM-1, and a low-grade systemic inflammation was indicated in increased levels of CRP.

Pneumoproteins and markers of inflammation and platelet activation in the blood of grain dust exposed workers.

PURPOSE: To investigate if blood biomarkers could indicate early signs of lung damage or cardiovascular risk due to exposure to grain dust. MATERIALS AND METHODS: Pneumoproteins and markers of inflammation and platelet activation were analysed in blood samples of 102 grain elevator and compound feed mill workers. Differences between exposed (n = 67) and controls (n = 35), and associations with exposure measurements and respiratory health were investigated by multiple linear regression analyses. RESULTS: Concentrations of CC-16 and IL-6 were higher in exposed workers compared with controls (p < 0.001 for both), whereas fibrinogen was lower (p = 0.005). Concentrations of CRP, TNF-α, sCD40L and sP-selectin were similar in both groups. Serum CC-16 was significantly higher in workers with farm childhood, regardless of exposure. The impact of farm childhood on CC-16 interacted with smoking. None of the biomarkers were associated with exposure measurements or any of the tested respiratory health parameters. CONCLUSION: Dust exposure induced inflammatory and anti-inflammatory reactions, but did not induce systemic inflammation and had no effect on platelet activation. No cause-effect relationship could be established in spite of relatively high exposure levels, particularly to endotoxin. Whether increased serum CC-16 is an early sign of lung damage or a reversible defense reaction remains unclear.

Hydrogen sulphide exposure in waste water treatment.

BACKGROUND: The aims of this study was to assess exposure to hydrogen sulphide (H2S) among waste water treatment workers (WWWs), and achieve a better measure of the risks of H2S exposure than only using the eight-hour average value and the ceiling value because the exposure pattern of H2S for WWWs is dominated by short-term peaks. METHODS: Ninety-three measurements of H2S from 56 WWWs in three cities and three rural areas were collected. All exposure measurements were carried out from the start of the day until lunch time (sampling time 4-5 h) when most of the practical work was performed. The type of tasks and extent of flushing were registered. H2S was measured using direct-reading instruments with logging: OdaLog L2/LL, Dräger X-am 5000 and Dräger Pac 7000 (0.1-200 ppm). Number and duration of peaks for different work tasks, seasons, places and extent of flushing were combined in an exposure index (IN), and evaluated in a mixed-model analysis, building a model aimed to predict exposure for different job tasks. RESULTS: Nine Percent (8 of 93) of all H2S measurements have peaks above 10 ppm; in addition, 15% (14 of 93) have peaks of 5-10 ppm, 35% (33 of 93) have peaks of 1-5 ppm and 65% (62 of 93) have peaks of 0.1-1 ppm. 29% of the measurements of hydrogen sulphide showed no registered level > 0.1 ppm.From the mixed-model analyses we see that exposure level, expressed as H2S index IN, varied between places, work type, season and degree of flushing. For the work in a plant in the capital, the exposure index varied from 0.02 for working in spring doing some flushing, to 0.7 for working at the same plant in winter doing flushing more than three times or more than 10 min. Collecting sewage from cesspools in city 2 in winter doing a lot of flushing gave a hydrogen sulphide index of 230. CONCLUSIONS: The use of a H2S index, taking into consideration peak height, duration and number of peaks, could be a tool for exposure assessment for H2S.

Profiling of 3-hydroxy fatty acids as environmental markers of endotoxin using liquid chromatography coupled to tandem mass spectrometry.

3-Hydroxy acids are constituents of the lipid A part of lipopolysaccharides and may potentially be used as chemical markers of endotoxin. While commercial enzymatic assays, such as the widely used Limulus amebocyte lysate (LAL) assay, commonly detect merely the water-soluble fraction of the bioactive endotoxin, the chemical approach aims to estimate the total amount of endotoxin present in a sample. Our objective was to develop a simple method for quantitative profiling of 3-hydroxy fatty acids in occupational and environmental samples based on detection with HPLC-MS/MS. We included eleven 3-hydroxy fatty acids (3-hydroxyoctanoic acid to 3-hydroxyoctadecanoic acid) in the HPLC-MS/MS based method, which involved base hydrolysis of filter samples using 1M sodium hydroxide and removal of the base as well as concentration of the fatty acids using solid-phase extraction on a functionalized polystyrene-divinylbenzene polymer. Recovery trials from spiked glass fiber filters, using threo-9,10-dihydroxyhexadecanoic acid as internal standard, gave an overall recovery of 54-86% for 3-hydroxy fatty acids of medium chain length (3-hydroxynonanoic to 3-hydroxypentadecanoic acid). 3-Hydroxyoctanoic acid and the longer chain fatty acids were more problematic yielding overall spike recoveries of 11-39%. While the 3-hydroxy fatty acid profile of pure lipopolysaccharides was dominated by 3-hydroxydecanoic, 3-hydroxydodecanoic and 3-hydroxytetradecanoic acid the aqueous phase from drilling mud contained in addition relatively high amounts of 3-hydroxyoctanoic and 3-hydroxynonanoic acid. Endotoxin activity as measured by the LAL assay was reasonably correlated (R(2)=0.54) to the sum of 3-hydroxydecanoic acid, 3-hydroxydodecanoic acid and 3-hydroxytetradecanoic acid in these samples.