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PubMed2002

[A prospective cohort study on the effect of occupational dust exposure and smoking on mortality].

OBJECTIVE: To study the effect of dust exposure and smoking on mortality. METHODS: Based on the Guangzhou Occupational Health Surveillance Record System established in 1989-1992, 61,648 factory workers, aged > or = 30, occupationally exposed to dust and non-exposure to dust or any other hazardous substances(controls), were included in a prospective cohort study. RESULTS: (1) 28 were lost to follow-up. Malignant neoplasm was most common among 1,186 deaths. (2) Most subjects were male workers, aged 35 to 44, with secondary education, and married. 42.2% had ever smoked and 32.8% were ever-drinkers. (3) To compare with non-exposure, non-smoking + non-smoking and non-exposure respectively, the adjusted RR of death from all causes, malignant neoplasm and respiratory diseases were 1.24, 1.34 and 1.96 respectively for dust exposed workers(compared to control, P < 0.01), 1.16, 1.37 and 1.63 respectively for those smoking(compared to non-smoker except RR of death from respiratory diseases, P < 0.01), and 1.48, 1.85 and 3.12 respectively for those smoking and dust exposure, which were far greater than those either smoked or exposed to dust alone(P < 0.01). (4) The influence of dust exposure on death was mainly showed in occupational exposure to silica dust and wood dust. CONCLUSION: Both dust exposure and smoking may increase the mortality, and they had synergistic effect.

Adult↗
PubMed2005

[Free crystalline silica: a comparison of methods for its determination in total dust].

BACKGROUND: The major objective of the study was to compare and investigate the usefulness of quantitative analyses of free crystalline silica (FCS) in the assessment of dust exposure in samples of total dust of varied composition, using three methods: chemical method in common use in Poland; infrared spectrometry; and x-ray powder diffraction. MATERIALS AND METHODS: Mineral composition and FCS contents were investigated in 9 laboratory samples of raw materials, materials, and industrial wastes, containing from about 2 to over 80% of crystalline silica and reduced to particles of size corresponding with that of total dust. Sample components were identified using XRD and FT-IR methods. Ten independent determinations of FCS with each of the three study methods were performed in dust samples. An analysis of linear correlation was applied to investigate interrelationship between mean FCS determinations. RESULTS: In analyzed dust samples, along with silica dust there were numerous minerals interfering with silica during the quantitative analysis. Comparison of mean results of FCS determinations showed that the results obtained using the FT-IR method were by 12-13% lower than those obtained with two other methods. However, the differences observed were within the limits of changeability of results associated with their precision and dependence on reference materials used. CONCLUSIONS: Assessment of occupational exposure to dusts containing crystalline silica can be performed on the basis of quantitative analysis of FCS in total dusts using each of the compared methods. The FT-IR method is most appropriate for the FCS determination in samples of small amount of silica or collected at low dust concentrations; the XRD method for the analysis of multicomponent samples; and the chemical method in the case of medium and high FCS contents in samples or high concentrations of dusts in the work environment.

Air Pollutants, Occupational↗
PubMed2006

[A prospective cohort study on comparison of risk of death of respiratory system diseases between occupational dust exposure and smoking].

OBJECTIVE: To compare the effects of dust exposure and smoking on mortality of respiratory system diseases (RSD). METHODS: Based on the Guangzhou Occupational Health Surveillance Record System established between 1989 and 1992, 80,987 factory workers, aged 30 years old or older, occupationally exposed or not exposed to dusts, were included in a prospective cohort study. RESULTS: (1) The mean age of the cohort was 43.5. Most subjects were workers, had secondary education, and almost all were married. The dust exposure rate was 16.3%, the smoking rate 43.7% and the alcohol-drinking rate 33.5%. (2) The cohort was followed up for 8 years on average, but 35 people (0.04%) were lost for follow up. Among the 1593 deaths, 219 and 90 people died of lung cancer and non-cancer respiratory system diseases (NCRSD) respectively. (3) The adjusted relative risk (RR) of death of lung cancer for smokers, 3.32, was 2.2 times of that for dust exposed workers, 1.53, and the RR of death of NCRSD for dust exposed workers, 2.41, 1.28 times of that for smokers, 1.89, especially for silica dust-exposed workers, 5.72, 3.03 times of that for smokers. Dust exposure combined with smoking caused significantly higher RR of death of RSD. (4) In male, the death risks of RSD were increased with the amount of smoking per day and years of smoking. CONCLUSION: Occupational dust exposure and smoking may cause excessive lung cancer and NCRSD death with synergistic effects. Smoking has higher RR of Lung cancer death than dust exposure. However, the dust exposure contributes to higher RR of NCRSD death. There is a significant dose-effect relationship between smoking and the death risk of RSD.

Adult↗
PubMed2006

[Effects of dusts on workers' health in enzyme production plants].

OBJECTIVE: To assess the health effects of dusts in enzyme production plants. METHODS: The concentration of enzyme-containing dusts, the enzyme and the wheat-containing dusts and their health effects on workers were investigated in three enzyme production plants. Air samples were collected by high volume sampler and personal sampler. Total dust was weighed and its content of enzyme was analyzed by enzyme activity method. Health effects were assessed by the questionnaire, the pulmonary function and the skin prick test. RESULTS: It was found that the geometric mean of enzyme-containing dust was 8.91 mg/m(3), the industrial enzyme was 1.68 mg/m(3), and the wheat-containing dust was 6.93 mg/m(3). The enzyme-containing dust higher than 20 mg/m(3) caused eye symptoms. The wheat-containing dust at 6.93 mg/m(3) might result in skin and nose symptoms. The sensitization could be observed in enzyme and wheat exposed workers. CONCLUSION: Adverse effects may arise for the health of the workers if the concentration of enzyme-containing dusts and the wheat-containing dusts is up to a certain limit and it is necessary to make the limit of these indexes.

Adolescent↗
PubMed1991

[The temporal variation of fine dust concentration in the air in fattening pig housing. Hygienic and occupational medicine aspects].

The temporal variation of airborne dust concentration (less than or equal to microns) was examined with an instrument operating on the nephelometer principle combined with a specifically adapted data processor in two pig fattening houses at night, at day and during feeding. Activities and factors affecting the dust level were noted. The measurement system allows the uptake and storage of values in the stable. For further processing, the data can be transmitted to a personal computer. In our experience the instrument is very suitable for the registration of airborne dust concentration in animal confinement buildings. Peak concentrations ranging up to 100 mg/m3 in intervals of 10 seconds could be measured. The data of a longer trial were averaged over 1.5 minutes. Animal activity has a great influence on the dust concentration. The highest mean concentration of dust with maximally 2.5 mg/m3 were determined at feeding time and when pigs were disturbed. The concentration of airborne dust particles was obviously lower at night than at day. A defect of the ventilation system, referable to the emission of feed dust, was disclosed by the continuous registration of air dust concentration, in one of the pig fattening houses. During the feeding periods, for a short time of less than 20 seconds, the dust concentration rises to 100 mg/m3 resp. 27 mg/m3 by dry resp. wet feeding. About 30 minutes after feeding the dust concentration was again in the average of 0.67 mg/m3. In conclusion the results were considered under hygienic and medical aspects.

Air Pollution↗
PubMed1987

Dust exposure in piggeries.

The aim of this study was to measure the total concentrations of dust in piggeries and to analyze the components of the dust. Dust samples were taken from 15 fattening pig and/or sow farms situated in southern Finland. Total concentrations of dust were measured by the gravimetric method; the organic portion of the total dust was determined by ashing, mass distribution determined by Cascade Centripeter sampler, count distribution by optical analyzer, and toxic metals of the total dust by atomic absorption spectrophotometer. The mean concentrations of total dust at stationary sampling sites were higher on fattening pig farms (9.4 +/- 1.7 mg/m3) (mean +/- SE) than on sow farms (5.2 +/- 1.2 mg/m3). The concentrations in the breathing zone were 8.6 +/- 2.7 mg/m3 and 7.9 +/- 3.2 mg/m3, respectively. The proportion of organic dust was about 90% in the dust of pig units. The mass median aerodynamic diameter of the dust particles in pig fattening units was 11 micron. Concentrations of toxic metals (nickel, cobalt, copper, zinc, chromium, cadmium) were very low.

Agricultural Workers' Diseases↗
PubMed1985

House dust mites in Colorado.

Sixty-four samples of house dust from 16 long-established households in the Denver, Colorado area were analyzed for the presence of house dust mites (Dermatophagoides sp.). No mites were found in house dust from 12 of the sampled houses and small numbers (10 to 40 mites/g of house dust) were found from the other four. In an additional four houses which contained furniture recently imported from other areas, 100 to 360 mites/g of dust were found, and 2 years later up to 200 mites/g were still present. Twenty-eight percent of the mites in repeat collections from the latter homes were alive. The mite allergen content of house dust samples was analyzed by RAST inhibition against pooled sera from mite allergic patients. When dust from four long-established Denver households where no mites were found was employed, there was an average binding of 37.2%; with dust from the four Denver households with low levels of mites and no imported furniture, binding averaged 39.5%. In contrast, with house dust from four "positive control" homes in California and New York there was only 26.1% binding (P less than .005). The results of this study suggest that there are small numbers of nonintroduced house dust mites in some Denver houses, but that they contribute little mite antigen and are probably of minimal clinical significance in mite-sensitive patients. Large numbers of mites can be introduced with furnishings and may persist for at least 2 years. Similar small mite populations might be expected in other areas with comparable relative humidity.

Allergens↗
PubMed1996

Analysis of the allergenic composition of rat dust.

BACKGROUND: Allergy to rats is an important occupational health problem. The allergens of rat urine have been well defined but those in rat room dust, a potentially important source of inhalant exposure, have not. OBJECTIVE: To describe the allergens present in rat room dust and to identify a suitable marker protein which may be used to quantify airborne rat allergen. METHODS: Dust collected from the air-conditioning system (bulk dust, 'bd') and with an air sampler (airborne dust, 'ad') were analysed by radioallergosorbent test (RAST) inhibition, immunoblotting and immunoblot inhibition techniques and comparisons made with hair and urine extracts prepared from adult male Wistar rats. RESULTS: Extensive crossreactivity was found between the extracts by RAST inhibition under different experimental conditions. Dust was more potent as an inhibitor than other extracts. The immunoblotting patterns of both dusts were similar although 'ad' contained an allergen at 29 kDa not found in 'bd'. Forty-two sera from rat allergic subjects were used to identify 18 allergens in 'bd'. Three 'major' allergens were found; 100% of subjects had immunoglobulin (Ig)E to a 44 kDa allergen and 74% and 88% of subjects had IgE with bound to the 20.5 and 17 kDa allergens respectively. Immunoblot inhibition experiments identified the 17 kDa dust allergen as alpha 2u-globulin (Rat nI). CONCLUSIONS: Rat dust is a complex allergenic source. The 17 kDa dust allergen has immunological identity with Rat nI and is a suitable marker protein for the quantitation of airborne rat allergen.

Air Pollutants↗
PubMed1996

Low-level exposure to house dust mites stimulates T-cell responses during early childhood independent of atopy.

BACKGROUND: The immune responses which underlie the expression of allergic symptoms in childhood are believed to be initiated in infancy and early childhood. The kinetics of this response have hardly been researched. OBJECTIVE: To analyse, in an environment with low house dust mite (HDM) exposure levels, the relationship between house dust mite (HDM)-specific T-cell reactivity as expressed by in vitro proliferation of blood mononuclear cells. METHODS: The study comprised a prospective analysis of patterns of allergen-specific T-cell reactivity in a cohort of 19 children, from whom blood samples were obtained in the spring during their second and third years of life. Blood mononuclear cell cultures were established in 200 microL AIM-V serum free medium. Crude house dust mite (HDM) and purified Der p 1 and Der p 2 extracts were used at optimal concentrations, i.e. 100 micrograms/mL for HDM and 30 micrograms/mL for the purified allergens. Tetanus toxoid (0.5 microgram/mL) and ovalbumin (10 micrograms/mL) served as positive controls. A clinical diagnosis of allergy was verified with skin-prick tests. Dust samples were collected from a mattress and/or carpet or sofa in homes, day care centres and day care homes. Major mite allergen levels (Der p 1/Der f 1) in dust were analysed by an enzyme linked immunosorbent assay (ELISA). RESULTS: Specific T-cell responses were seen in the majority of the children against house dust mite (crude HDM extract, Der p 1 and Der p 2). The levels of the house dust mite allergens Der p 1 and Der f 1 were low, i.e. < 0.68 microgram/g fine dust in the homes of the children and the day care centres that they were attending. This indicates that doses of mite antigen well below the suggested sensitization threshold level of 2 micrograms/g dust can induce mite-specific T-cell responses in young children. None of them showed clinical reactivity to house dust mites as indicated by negative skin-prick tests. CONCLUSIONS: The findings suggest that active immunological recognition of environmental allergens and the ensuing initiation of allergen-specific T-cell responses, is a normal part of the 'education' of the immune system in early childhood and can occur even at very low exposure levels. Priming per se does not imply clinically significant sensitivity, however.

Animals↗
PubMed1996

Chronic exposure of pigs to airborne dust and endotoxins in an environmental chamber: technical note.

A new experimental setup was developed to expose pigs to dust and airborne endotoxins in an environmental chamber, at levels liable to be encountered in pig farm buildings. The following parameters were evaluated in a chamber containing two pigs of 10 kg body-weight: inhalable and respirable dust gravimetric concentrations were measured using area samplers and expressed as mg/m3. The respirable dust concentration was also measured using a "TM digital microP respirable dust-measuring instrument', which has been shown to give similar results to the gravimetric method. The endotoxin concentration was evaluated using the Limulus-assay and expressed as ng/m3 of air containing the inhalable or respirable dust or as ng/mg of inhalable and respirable dust. Feed flour dust was introduced into the chamber to obtain different concentrations of inhalable and respirable dust ranging from 3.62 to 76.66 mg/m3 and from 0.24 to 1.40 mg/m3, respectively. The endotoxin concentration was modulated by mixing the feed flour with Escherichia coli endotoxins before blowing it into the chamber. The endotoxin concentrations in the air containing inhalable or respirable dust ranged from 28.9 to 270.0 ng/m3 and from 2.22 to 36.38 ng/m3, respectively, depending on the amount of endotoxins added to the dust. Data were also obtained in a piggery. The experimental setup detailed in this paper could be used to study the significance of air contaminants in the development of pig respiratory diseases.

Air Pollution, Indoor↗
PubMed1996

[Dust and microorganism count at delivery, sorting and composting of home refuse and home refuse-like industrial waste].

The exposure of employees to airborne dust and microorganisms was assessed in a waste processing plant established to recover reusable materials from unsorted domestic and industrial waste. Exposure criteria considered relevant were the quantity of the individual size-selected particle fractions, the morphological properties of the particles, their heavy metal content, and the degree of their contamination with various microorganisms and mold. In addition, separate microbiological analyses to determine potential pathogen concentrations in the air were made. The highest concentrations of total and fine dust were measured in the waste delivery area. A close correlation between the frequency of deliveries and the level of dust exposure was observed. In this area, fine dust concentrations exceeded the threshold limit value of 6 mg/m3 repeatedly for shorter periods. The average fine dust concentration during an entire work-shift, however, was considerably lower than this value. Particles with an aerodynamic diameter of 2 to 7 microns predominated both in the waste delivery and the processing areas. Fibrous dust particles were present in smaller numbers than spherical particles and consisted mainly of organic materials. Natural and artificial inorganic fibers were found only occasionally. The concentrations of lead, cadmium, nickel and mercury were considerably lower than the corresponding MAK and TRK values, and were--with the exception of lead--in the range of the respective metal concentrations in the atmosphere of urban areas. Microscopical examinations of used protective masks (protection category P2) revealed that dust particles were deposited even on the inner side of the masks. Most of the particles on this side were very small and carried nickel or titanium. Microorganism concentrations measured in air from the highly dust-exposed areas of the plant showed values up to 6.9 x 10(5) cfu/m3, with a mold content of 6.6 x 10(4) cfu/m3. Approximately 90% of the microorganisms were deposited on particles of the fine dust fraction (particle size < 7 microns), and more than 50% contaminated particles with an aerodynamic diameter of 2 to 4.7 microns. In the compost facility, mold concentrations of up to 8.4 x 10(5) cfu/m3 were measured. In contrast, the level of microbial contamination in the filtered air from the compost facility did not exceed the concentration measured in air outside the plant. The data which were obtained during the winter months are probably at the lower end of the average exposure range over the entire year. In regard to exposure assessment, it should be mentioned that particles with a size of 4 to 7 microns are not really "inert" particles, since they are preferential carriers for heavy metals and microorganisms. More studies in the future should be performed to establish, whether the level of exposure to microorganisms can be estimated indirectly by the determination of dust exposure.

Air Microbiology↗
PubMed1997

Seasonal variation of skin reactivity and specific IgE antibody to house dust mite.

BACKGROUND: House dust mite is an important cause of bronchial asthma worldwide. While the allergen is present all year-round, a seasonal variation of house dust mite allergen levels has been found. There have been few reports, however, on seasonal variation of specific immune response to house dust mite. OBJECTIVE: We studied the changes in skin reactivity and specific IgE antibody to house dust mite associated with seasonal variation of house dust mite allergen levels in houses of mite-sensitive asthmatic patients. METHODS: In 14 mite-sensitive asthmatic patients, house dust mite allergen (Der f 1) contents in bedding were measured monthly. Skin reactivity on prick test and specific IgE antibody to house dust mite, Dermatophagoides farinae (D. farinae), were determined every 3 months from july to December. RESULTS: The concentration of Der f 1 in dust from bedding reached maximum levels in August and September, and significantly decreased in November and December compared with August and September (P < .05). Skin reactivity (a ratio of mean wheal diameter of allergen to histamine) to D. farinae decreased significantly in December compared with September (P < .05). Serum levels of total IgE and specific IgE antibody to D. farinae decreased significantly in December compared with September (P < .05). CONCLUSION: These findings suggest that seasonal changes in natural exposure to house dust mite allergen might lead to concurrent changes in skin reactivity and specific IgE antibody to house dust mite in mite-sensitive asthmatic patients.

Adolescent↗
PubMed2005

Extreme collisions between planetesimals as the origin of warm dust around a Sun-like star.

The slow but persistent collisions between asteroids in our Solar System generate a tenuous cloud of dust known as the zodiacal light (because of the light the dust reflects). In the young Solar System, such collisions were more common and the dust production rate should have been many times larger. Yet copious dust in the zodiacal region around stars much younger than the Sun has rarely been found. Dust is known to orbit around several hundred main-sequence stars, but this dust is cold and comes from a Kuiper-belt analogous region out beyond the orbit of Neptune. Despite many searches, only a few main-sequence stars reveal warm (> 120 K) dust analogous to zodiacal dust near the Earth. Signs of planet formation (in the form of collisions between bodies) in the regions of stars corresponding to the orbits of the terrestrial planets in our Solar System have therefore been elusive. Here we report an exceptionally large amount of warm, small, silicate dust particles around the solar-type star BD+20,307 (HIP 8920, SAO 75016). The composition and quantity of dust could be explained by recent frequent or huge collisions between asteroids or other 'planetesimals' whose orbits are being perturbed by a nearby planet.

Journal Article↗
PubMed1986

Relation between dust exposure and lung function in miners and ex-miners.

A sample of men working in the British coal industry in the 1950s has been followed up and examined 22 years later. The relations between lung function and individual cumulative exposure to respirable dust have been studied in 1867 men who were still working in the industry at the time of follow up and 2192 men who had left. Levels of forced expired volume in one second (FEV1), forced vital capacity (FVC), and FEV1/FVC ratio at follow up were found to be inversely related to exposure to respirable dust after allowing for other factors, even in men without pneumoconiosis. The magnitude of this estimated effect was equivalent to a loss of 228 ml FEV1 in response to an exposure of 300 gh/m3, a moderately high exposure for this group. Ex-miners aged under 65 had worse lung function than miners on average, suggesting that ill health had encouraged some of these men to leave the industry. Whereas a more severe response to dust exposure among ex-miners under 65 was suggested, this difference could easily have arisen by chance. The presence of symptoms of chronic bronchitis was associated with reduced levels of lung function, however, and, additionally, ex-miners under 65 with chronic bronchitis showed a more severe response of the FVC to dust exposure than miners without these symptoms. Among these ex-miners with chronic bronchitis a small group of men who had taken other jobs showed a much more severe effect of dust exposure on their lung function than the average, likely in heavily exposed men to contribute importantly to disability. Men in this group who had given up smoking showed and even more severe effect of dust exposure, equivalent to a loss of 940 ml FEV1 in response to an exposure of 300 gh/m3. These results indicate that exposure to respirable dust can occasionally cause severe respiratory impairment in the absence of progressive massive fibrosis. Dust exposure was related to a parallel reduction of FEV1 and FVC, implying that the pathology of dust induced lung damage differs form that induced by smoking. This pattern of abnormality was shown by some non-smokers, whereas smokers and ex-smokers apparently severely affected by dust showed a classic obstructive pattern of abnormality with pronounced reduction of the FEV1/FVC ratio.

Aged↗
PubMed1982

Electron microscopic investigations on dust penetration into the pulmonary interstitium in experimental pneumoconioses.

Pneumoconioses produced by intratracheal applications of various dusts (quartz, coal, cadmium and lead sulfide) in rats were investigated by electron microscopy in order to follow the pathway of the dust particles from the alveoli into the pulmonary interstitium. As postulated by Spencer in 1977 on the basis of light microscopic investigations, the dust particles produce necroses of the alveolar septae ('alveolar ulcers'). TWo forms of necroses appear to occur: with a less severe dust exposure, individual pneumocytes and their basement membrane are destroyed by dust particles. Dust-laden, macrophages are deposited here which are displaced into the stroma after re-epithelization of the alveolar defect. On the other hand, with massive dust exposure, almost all pneumocytes of the affected alveoli become necrotic. The affected alveoli collapse and are replaced by connective tissue, so that the dust is situated in the connective tissue stroma. A transcellular penetration of the dust particles into the pulmonary interstitium or an immigration of dust-laden macrophages into the pulmonary stroma through the intercellular junctions of intact pneumocytes was not observed in any of the pneumoconiosis models.

Animals↗
PubMed1980

[Biological and histological changes induced by cement dust].

In animal experiments pneumoconiogenic properties of metallurgic and Portland cement dust, produced in Poland, were investigated. Experimental pneumoconiosis was developed by intratracheal single administration, to white rats, of 50 mg of dust suspended in 0.6 ml of NaCl physiological solution. The control groups were composed of animals to whom intratracheally physiological NaCl solution, TiO2 dust and two quartz dusts of varying fibrogenic properties--weak and mild, were administered. The content of crystalline silica, as determined chemically, was approx. 3% in both cement samples. X-ray diffraction did not show any content of crystalline phases in the cements, TiO2 dust contained rutile, whereas both quartz dusts contained about 100% alpha-quartz. After 3 months the animals were sacrificed. Wet lungs weight and hydroxyproline content in lungs were determined. In addition, mediastinal nodes and lungs were examined histologically. Cement dust was found to exhibit weak fibrogenic properties, not different significantly from fibrogenic properties of inert TiO2. Nevertheless increases in fibrogenic effect of cement dusts were significantly higher as compared to the control group (geometric mean hydroxyproline content in the control group was 2.52 +/- 0.06 mg, 4.50 +/- 0.09 in the Portland cement and 4.88 +/- 0.06 in metallurgic cement. Histological changes in lungs, due to cement effect are not progressive, expressing merely inflammatory reaction to dust. Nevertheless despite weak fibrogenic properties the cement dust provokes lesions of macrophages in lungs.

Animals↗
PubMed1999

Cotton dust and endotoxin exposure and long-term decline in lung function: results of a longitudinal study.

BACKGROUND: To evaluate the relationship between long-term exposure to cotton dust and Gram-negative bacterial endotoxin on lung function, we conducted an 11-year follow-up study of cotton textile workers in Shanghai, China. METHODS: Workers at a nearby silk-thread manufacturing mill were used as a referent population. Ninety percent of the original cohort of 445 cotton and 467 silk textile workers--both active and retired--were identified for testing in the 11th year. Questionnaires and spirometric testing were performed, as well as cotton dust and endotoxin sampling at three points over the 11-year follow-up period: at baseline, at Year 5, and at Year 11. After excluding deaths and subjects on sick-leave, 84% of the original cohort had complete health and environmental data. RESULTS: The data were reanalyzed using generalized estimating equations feedback model which allow for subject transfer over time between work areas, various exposure levels to dust and endotoxin, and FEV1. Cotton workers had a larger loss of FEV1 during the first 5 years of study (-40 mls/yr) as compared with the second 6 years of follow-up (-18 mls/yr). During the same periods, the average decline among silk workers was slightly higher in the first period, but was more consistent (-30 mls/yr vs. -27 mls/yr), and these differences could not be explained by worker selection or dropout. When cumulative exposure to dust and endotoxin were estimated and used in a multivariate model (GEE) for FEV1 loss, cumulative dust, but not endotoxin, was associated with 11-year loss in FEV1 after adjustments for confounders. There was evidence of feedback between dust-exposure levels and FEV1, indicating the existence of a healthy-worker survivor effect. After accounting for a healthy-worker survivor effect, we found a significant relationship between dust exposure and FEV1 decline. CONCLUSIONS: Our results suggest that cotton dust is more strongly associated with chronic airflow limitation than associated endotoxins. Further work is needed to clarify potential reversibility after cessation of exposure, and the relative contributions of dust, endotoxin, and tobacco to chronic respiratory impairment in cotton and other vegetable-exposed workers.

Case-Control Studies↗
PubMed1993

Relationship of respiratory health status to grain dust in a Witwatersrand grain mill: comparison of workers' exposure assessments with industrial hygiene survey findings.

Objective measures of exposure furnished by dust monitoring are both costly and time consuming and require a sufficient level of technology. However, they are important in demonstrating exposure-response relationships, in furnishing information necessary to establish environmental control levels, and to assess if interventions, for instance, improving dust control, have been effective. In this paper respiratory symptoms and cross-shift changes in spirometric lung function were related to dust exposure level in a grain mill assessed in two ways, subjectively (by workers themselves on a four point scale) and objectively (by personal dust monitoring). Health indicators that depend on the individual's perception (e.g., symptoms) correlated more closely with the subjectively assessed dust category, while health indicators that were measured objectively (e.g., cross-week FVC and FEV1 change) correlated more closely with the objectively assessed dust category. However, the patterns of relationship of respiratory health indicators to either dust category were similar, and exposure assessed by one method was, to a large extent, a proxy for the other. The most significant predictor of workers' choice of dust exposure category was the measured dust level. These findings indicate that exposure categories based on workers' assessment of dustiness can be a useful tool in etiologic research, in particular in establishing exposure-response relationships.

Dust↗