Surfactant protein-D and exposure to bioaerosols in wastewater and garbage workers.
OBJECTIVE
Bioaerosols and their constituents, such as endotoxins, are capable of causing an inflammatory reaction at the level of the lung-blood barrier, which becomes more permeable. Thus, it was hypothesized that occupational exposure to bioaerosols can increase leakage of surfactant protein-D (SP-D), a lung-specific protein, into the bloodstream.


METHODS
SP-D was determined by ELISA in 316 wastewater workers, 67 garbage collectors, and 395 control subjects. Exposure was assessed with four interview-based indicators and by preliminary endotoxin measurements using the Limulus amoebocyte lysate assay. Influence of exposure on serum SP-D was assessed by multiple linear regression considering smoking, glomerular function, lung diseases, obesity, and other confounders.


RESULTS
Overall, mean exposure levels to endotoxins were below 100 EU/m(3). However, special tasks of wastewater workers caused higher endotoxin exposure. SP-D concentration was slightly increased in this occupational group and associated with the occurrence of splashes and contact to raw sewage. No effect was found in garbage collectors. Smoking increased serum SP-D. No clinically relevant correlation between spirometry results and SP-D concentrations appeared.


CONCLUSIONS
These results support the hypothesis that inhalation of bioaerosols, even at low concentrations, has a subclinical effect on the lung-blood barrier, the permeability of which increases without associated spirometric changes.
Daneshzadeh Tabrizi
R
R
Occupational and Environmental Medicine Unit, University of Zurich, Med. Poliklinik USZ, Rämistrasse 100, 8091, Zurich, Switzerland.
Bernard
A
A
Thommen
A M
AM
De Winter
F
F
Oppliger
A
A
Hilfiker
S
S
Tschopp
A
A
Hotz
P
P
D000328:Adult; D000336:Aerosols / Q000009:adverse effects* / Q000032:analysis; D016022:Case-Control Studies; D004391:Dust / Q000032:analysis; D004731:Endotoxins / Q000009:adverse effects / Q000032:analysis; D004784:Environmental Monitoring / Q000379:methods; D004797:Enzyme-Linked Immunosorbent Assay; D062665:Epidemiological Monitoring; D005260:Female; D005735:Garbage; D006801:Humans; D007407:Interviews as Topic; D016014:Linear Models; D008297:Male; D008875:Middle Aged; D016273:Occupational Exposure / Q000009:adverse effects* / Q000032:analysis; D009790:Occupations / Q000145:classification / Q000706:statistics & numerical data; D037663:Pulmonary Surfactant-Associated Protein D / Q000097:blood*; D018570:Risk Assessment; D012307:Risk Factors; D012722:Sewage / Q000009:adverse effects / Q000032:analysis; D012907:Smoking / Q000009:adverse effects / Q000453:epidemiology; D013557:Switzerland / Q000453:epidemiology; D014865:Waste Disposal, Fluid; D055815:Young Adult
D000336:Aerosols; D004391:Dust; D004731:Endotoxins; D037663:Pulmonary Surfactant-Associated Protein D; D012722:Sewage