Endotoxin exposure as a major determinant of lung function decline in pig farmers - Vogelzang,P.F.; Joost,W.J.; v d Gulden,H.F.; Kolk,J.J.; Heederik,D.; Preller,L.; Thiel,M.J.; v Schayck,C.P. (Am J Resp Crit Care Med, 1998)