[Review of risks of biological agents and preventive measures to safeguard the health of compost production workers]. / Rassegna dei rischi da agenti biologici e interventi preventivi per la tutela della salute degli addetti agli impianti di produzione del compost.

A review of studies made in the compost production industry showed the biological agents posing a risk for workers were fungi and thermophile bacteria, gram-negative bacteria and endotoxins, with a prevalent inhalation exposure to airborne contaminated dusts. Medical examinations revealed cases of extrinsic allergic alveolitis due to A. fumigatus, and more frequently irritative and infectious disorders occurring especially in conditions of poor environmental hygiene and macroscopic dust pollution. For the evaluation of the air dispersion of microorganisms, which is high in compost transport and turning operations, at present no exposure limit values are available for biological agents; nevertheless, the concentrations measured were often higher than the limit values proposed for other manufacturing sectors by individual authors and by regulatory agencies in Europe, and were comparable to values observed in other industrial settings for which adverse health effects have been shown. Although the number of studies available are few in number, the results suggest that the hazards posed by microorganisms and the poor environmental hygiene conditions often encountered can undoubtedly be a source of risk for workers, which at present is difficult to establish but significant considering the high airborne concentrations of contaminated dust. Besides technical measures to avoid environmental macroscopic dispersion of dusts, measurement of airborne microbiological contaminants is also recommended. Health surveillance needs to be aimed at identifying subjects with hypersusceptibility to the infectious action of the pathogenetic and/or allergenic agents or with hypersensitivity to the same, and also to periodic control of respiratory organs.

Generation of vasoactive peptide bradykinin from human umbilical vein endothelium-bound high molecular weight kininogen by plasma kallikrein.

High molecular weight kininogen (HK) is a multifunctional plasma glycoprotein that occupies a critical position in pathways that link inflammation and coagulation. It is an inhibitor of sulfhydryl proteases and has procoagulant properties. It is also a source of the vasoactive peptide bradykinin (BK). It has been previously shown that HK binds to human umbilical vein endothelial cells (HUVEC) in culture. We have further characterized that interaction herein. Immunohistochemical experiments have indicated that when freshly obtained umbilical vein segments were treated with HK, washed, and probed with anti-HK antibodies, HK was localized on the endothelium. We next determined whether HUVEC-bound HK can be cleaved by plasma kallikrein to release BK. Cultured HUVEC were incubated with unlabeled HK for varying times, washed, and the kinetics of BK release by plasma kallikrein were assayed by radioimmunoassay. Results indicated that kallikrein released BK from HUVEC in proportion to the initial amount of bound HK. No release of BK occurred in the absence of kallikrein. Also, there was no BK release upon kallikrein treatment of the HUVEC not treated with exogenous HK. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis and autoradiography of HUVEC-bound 125I-HK indicated that addition of kallikrein resulted in cleavage of HK, thus corroborating the BK release experiments. Comparison of cleavage patterns has also indicated that cell-bound HK is slightly less susceptible to digestion by kallikrein than free HK. Therefore, our data suggest that human HK can bind to vascular endothelium in situ and that plasma kallikrein can recognize endothelial-bound HK as a substrate and liberate the vasoactive peptide BK.