The effect of exposure to organic dust on the change in lung function over time, study results
| Exposure, first author (year) | Exposure | Results, adjusted exposed versus controls | Results, adjusted exposure–response (ER) | Main findings | Results summarised |
| Cotton workers | |||||
| Glindmeyer (1991)30 | Cotton textile workers versus synthetic textile workers (controls) | Cotton workers had smaller decline in lung function than controls. FEV1: +13.14 mL/year±3.13 (p<0.01); FVC: +6.45 mL/year±3.72 (NS) | Only subgroup showed ER per 100 µg/m3 cotton dust increase: FEV1: −16.2 mL/year±3.27, (p<0.01); FVC: −18.0 mL/year±3.94 (p<0.01) | Significant positive association (smaller lung function decline among cotton workers); overall no ER | + pos. W versus C for FEV1; − ER |
| Wang (2003)31 | Newly hired cotton workers, no controls | N/A | Endotoxin was not associated to change in FEV1 and FVC, but dust was marginally significant for FVC: −103.8 mL/year±58.8, (p=0.08) | Cotton dust was not associated with changes in lung function after 1-year follow-up | − ER |
| Wang (2005)14 | Cotton workers/silk workers (controls) | Cotton workers had greater decline in FEV1 compared with controls: −18 mL/year±8.8 (p<0.01) | Greater loss in FEV1 with increasing endotoxin: highest versus lowest level: −7.8 mL/year±3.8 (p<0.05) | Cotton work and increasing endotoxin was associated with greater decline in FEV1. | + neg. W versus C for FEV1; +ER for FEV1 |
| Grain workers | |||||
| Huy (1991)32 | Grain elevator workers/controls | Grain workers and controls showed same annual changes in FEV1 and FVC (NS) | Grain dust (mg/m3) was associated with FEV1 % pred.: −0.89±0.39 (p<0.05), FVC % pred.: −0.73±0.35 (p<0.05) | Both level and duration of dust exposure were associated with excess decline in lung function. | − W versus C; +ER for FEV1 and FVC |
| Olfert (2005)33 | Young grain workers | N/A | Exp. weeks were associated with decline in FEV1: coeff. (95% CI) −0.6 mL (−0.8 to −0.3); FVC: −0.7 mL (−1.0 to −0.3) | Exp. weeks were associated with lung function decline. | +ER for FEV1 and FVC |
| Pahwa (2008)15 | Grain workers; no controls | N/A | Years in grain industry was associated with decline in FEV1: −4.0 mL±0.2 (p<0.0001); FVC −6.0 mL±0.3 (p<0.0001) | Years in the grain industry was associated with decline in lung function. Grain dust control was effective in reducing this decline. | +ER for FEV1 and FVC |
| Post (1998)34 | Grain processing and animal feed workers | No difference in decline in lung function between >5 years of exp. versus no exp. <5 years (no size of estimate) | Decline in FEV1: high dust exp.: −58.2 mL/year versus low dust exp.: −35.8 mL/year (p<0.05) | Dust exp. was associated with excess decline in FEV1. | +ER for FEV1 |
| Senthilselvan (2010)35 | Grain farmers/controls | Grain farmers had an excess annual decline in FVC of 9.2 mL/year (95% CI 2.7 to 15.8, p=0.006) compared with controls. | No significant ER between change in FEV1 or FVC per year and years of grain farming (no size of estimate) | Excess decline of 9.2 mL/year in FVC in grain farmers compared with controls | + neg. W versus C for FVC; − ER |
| Farmers | |||||
| Bolund (2015)36 | Farmer/control; dust and endotoxin during the follow-up period | Change in lung function: ΔzFEV1: ex-farmer: 0.05 (−0.07 to 0.16) NS; current farmer: −0.07 (−0.19 to 0.05) NS; similar for FVC | No ER for either dust (ΔzFEV1: 4th quart vs 1st quart: −0.02, p=0.733) or endotoxin (ΔzFEV1: 4th quart vs 1st quart: −0.03, p=0.662) among farmers; similar for FVC | No differences in change in lung function between farmers and controls | − W versus C; − ER |
| Gainet (2007)37 | Farmers/controls | Farmers versus controls: FEV1: −1.75 mL/year±4.08 (NS); FVC: 2.92 mL/year±5.02 (NS) | The duration of exposure was significantly associated with excess decline in FEV1 (−28.7 mL/year, p<0.05). | No difference in lung function change between farmers and controls, but ER between work duration and FEV1 decline | − W versus C; + ER for FEV1 |
| Iversen (2000)20 | Pig farmers/dairy farmers (controls) | Decline in FEV1 for pig farmers versus dairy farmers: −11.0 mL/year±6.33 (p=0.084, NS) | N/A | No difference in lung function change between farmers and controls | − W versus C |
| Mauny (1997)38 | Barn-drying farmers (BD)/traditional drying farmers (TD) | No difference in decline in lung function between BD farmers and TD farmers for VC or for FEV1 | Cumulated exp. (bale-years) was not correlated with the changes in lung function, VC: 6.4 mL±6.9, NS; FEV1: 2.09 mL±5.5, NS | The mode of fodder drying did not significantly influence the decline in lung function. | − W versus C; − ER |
| Schwartz (1995)21 | Swine confinement workers and neighbourhood control farmers | Swine confinement work was associated with decline in FEV1: −38 mL/year±12 (p<0.01) compared with control farmers | Total endotoxin (EU/m3) was associated with decline in FEV1: −26 mL/year±8 (p<0.01). | Significant association between swine work and accelerated lung function decline; ER for endotoxin on FEV1 | + neg. W versus C for FEV1; +ER for FEV1 |
| Senthilselvan (1997)39 | Swine farmers/controls | Swine confinement workers had excess annual decline of 26.1 mL in FEV1 (p=0.0005) and 33.5 mL in FVC (p=0.0002) compared with controls. | N/A | Accelerated yearly loss in lung function seen among swine confinement workers compared with controls | + neg. W versus C for FEV1 and FVC |
| Thaon (2011)16 | Dairy farmers/non-dairy agricultural workers/controls | Dairy farmers had no increased loss in FEV1 or FVC compared with controls (p>0.10). Greater decline in FEV1/FVC (−0.21%/year±0.08, p=0.01) was seen for dairy farmers. | An increased decline in FEV1 for all agricultural workers was associated with years of exp. with animal feed handling (−0.71±0.32, p=0.03). | Years of exp. with animal feed handling was associated with decline in FEV1. | + neg. W versus C for FEV1/FVC only; +ER for FEV1 |
| Vogelzang (1998)40 | Pig farmers; no controls | N/A | Endotoxin exp. (factor 2 increase) associated with FEV1: −19.4 mL/year±10.9 (p=0.04); FVC: −40.7 mL/year±14.2 (p=0.002); dust associated with FVC: −41.2 mL/year±21.0 (p=0.03) | Exp. to endotoxin was associated with decline of FEV1 and FVC; exp. to dust was associated with decline of FVC alone. | +ER for FEV1 and FVC |
| Paper workers | |||||
| Sigsgaard (2004)19 | Paper workers/controls | The lung function decline among the controls was comparable with that of the exposed (NS). | Endotoxin exp. was not associated with FEV1 (no size of estimate) but with increase in FVC: high exp.: 23.4 mL/year±8.9 (p=0.009) (opposite of expected). | No significant excess loss of lung function was seen among workers exposed to paper dust. | − W versus C; + pos. ER for FVC |
| Wood workers | |||||
| Glindmeyer (2008)41 | Wood processing workers; no controls | N/A | Exp. to wood solids was not associated with significant adverse effects on lung function (no size of estimate). | No association between wood solids and change in lung function. | − ER |
| Jacobsen (2008)42 | Woodworkers/controls. | Only female woodworkers had a larger decline in FEV1 than controls: −10.6 mL/year±4.97 (p=0.03); male: 6.1±3.3 (p=0.07) | ER between cumulative wood dust exp. (mg/m3) and annual decline in lung function for female workers FEV1: −3.1 mL/year (p=0.01); FVC: −3.0 mL/year (p=0.02) | Females, but not males, had an accelerated decline in lung function in a cohort exp. to relatively low concentrations of wood dust. | + neg. W versus C for FEV1; +ER for FEV1 and FVC (females only) |
| Noertjojo (1996)43 | Western red cedar sawmills workers/controls | Sawmill workers had a greater decline in FEV1: −12.1 mL/year (p=0.01) and FVC: −14.6 mL/year (p<0.05) compared with the control subjects. | ER between wood dust exp. and annual decline in FVC: high exp.: −21.3 mL/year±10.3 (p<0.05); annual decline in FEV1 was significant only for medium wood dust: −16.9±6.0 (p<0.05). | Sawmill workers had a greater decline in FEV1 and FVC than controls. | + neg. W versus C for FEV1 and FVC; +ER for FVC |
Results given as coefficient±SEM unless otherwise specified.
+ pos., significant positive association; + neg., significant negative association; C, control; ER, exposure–response for dust/endotoxin level or exposure time; exp., exposure; FEV1, forced expiratory volume in the 1st s; FVC, forced vital capacity; NS, non-significant; VC, vital capacity; W, worker; -, No association.