ORIGINAL ARTICLE

Short term changes in lung function, leukocytosis in blood, and lachrymal fluid among bacterial single cell protein workers after an episode with high exposure to endotoxins

M Skogstad¹, W Eduard¹, J Holme², T Qvenild² and E Einarsdottir¹

¹ National Institute of Occupational Health, PO Box 8149 Dep, NO-0033 Oslo, Norway
² Occupational Department, St Olavs Hospital, NO-7000 Trondheim, Norway

Correspondence to:
Correspondence to:
Dr M Skogstad
National Institute of Occupational Health, PO Box 8149 Dep, N-0033 Oslo, Norway; Marit.Skogstad{at}stami.no

Aims: To study possible effects of endotoxin exposure among bacterial single cell protein workers on pulmonary function, blood parameters, and lachrymal fluid before and after a work shift.

Methods: The study included 23 men and five women who were examined at the start and at the end of a work shift. Most workers performed a task with unusually high exposure levels. Twelve of the workers were re-examined the day after. The workers were divided into three exposure groups: production workers with the highest assumed exposure levels (n = 18), engineers (n = 5), and clerks (n = 2). The median endotoxin level during a work shift was 34000 EU/m³ in the high exposure group (range 3300–89000 EU/m³ ), 11000 EU/m³ (range 350–27000 EU/m³) among the engineers, and 180 EU/m³ (range 60–300 EU/m³) for the clerks. The workers answered a questionnaire about work related symptoms. Assessment of lung function included dynamic lung volumes and flows. The blood analysis included cell count of leukocytes and mediators of inflammation, fibrinogen, interleukin-6 (IL-6), D-dimer, and C-reactive protein (CRP). Cells in lachrymal fluid were counted with a microscope.

Results: The forced vital capacity (FVC) changed significantly (p<0.05) from 5.34 l (SD 0.9) to 5.25 l (SD 0.9) and forced expired volume in one second (FEV1) from 4.15 l (SD 0.7) to 4.07 l (SD 0.7) during the work shift. The leukocytes increased significantly (p<0.05) from 6.9 10⁹/l (SD 1.2) to 7.7 10⁹/l (SD 1.5) and IL-6 from 1.5 ng/l (SD 0.6) to 3.31 ng/l (SD 2.7). Except for fibrinogen, which had a borderline increase and PEF that decreased, the parameters were normalised the day after. Four of the workers had an increase of neutrofile granulocytes in the lachrymal fluid during the shift. There was a significant association between the endotoxin concentration and decrease of FEV1 despite the use of powered respirators.

Conclusions: During a work shift with unusual high levels of endotoxins at a plant manufacturing bacterial single cell protein the results show that FVC and FEV1 were reduced. Mediators of inflammation increased along with leucocytosis in blood and lachrymal fluid among the workers.

Abbreviations: CRP, C-reactive protein; EU, endotoxin unit; FVC, forced vital capacity; FEV1, forced expiratory volume in 1 second; IL-6, interleukin-6; SCP, single cell protein

Keywords: endotoxins; short term exposure; pulmonary function; inflammation; single cell protein; bacteria

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