Objective Bioprotein or bacterial single-cell protein (SCP) consists of dry bacterial biomass mainly of a single gram-negative species, which contains endotoxins. Used as animal feed, bioprotein was produced in a biotechnology plant in Norway from 1999 until 2006, when the plant was closed down. This paper summarizes four previously published studies, where we aimed to explore the inflammatory effects of endotoxin exposure from bacterial SCP on the plant employees.

Methods Most of the 28 workers that were examined in 2003 and 2005, among them five women, worked full-time at the plant. We collected blood, measured lung function, and performed sputum analysis.

Results Our previous findings showed that exposure to endotoxins exceeded 200 endotoxin units/m³ in 80% of the measurements. During a work shift in 2003, significant decreases in forced vital capacity (FVC) and forced expiratory volume in one second (FEV₁) were detected along with an increase in the white blood cell count and serum IL-6 (interleukin-6). In 2005, compared to a control group, an abundance of neutrophils was detected in the sputum of the workers handing bioprotein in addition to circulating lipopolysaccharides (LPS) and increased inflammatory markers in plasma.

Conclusion Prolonged exposure to bacterial SCP, resulting in inhalation of endotoxin into the blood, is probably the cause of inflammatory responses in the lung and blood.

Key terms bacteria; bacterial single cell protein; bioprotein; discussion paper; endotoxin; endotoxin exposure; exposure; lung; lung function; pulmonary function; SCP; single cell protein; systemic inflammation; worker