RR1043 – Endotoxin in metal working fluid (MWF) mist

The risks to respiratory health from exposure to bacterial endotoxins are well established. The aims of this
research were to:

  • Review the evidence used to develop the health based recommended occupational exposure limit (HBROEL) for endotoxin of 90 endotoxin units per cubic metre (EU/m3) over an 8-hour period proposed
    by the Health Council for the Netherlands (DECOS); and to assess its relevance as a ‘benchmark’ to
    assess risks to respiratory health caused by endotoxin in metal working fluid mists.
  • Assess whether the published evidence on endotoxin concentration in metal working fluids provides
    sufficient evidence that concentrations in mist are sufficient to cause harm to human health

The research concluded that there was a large discrepancy between concentrations of endotoxin and viable bacteria in mist compared to the concentrations in bulk fluid with airborne endotoxin levels generally falling close to or beneath the DECOS recommended level , whilst sump levels generally exceeded these by 100 to 1000 fold. Levels of viable bacteria captured in air were low compared to the levels in the sumps.

Further research is required to determine whether the discrepancy between bulk endotoxin and airborne levels is real or whether this is due to the impact of sampling or analytical methodology

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Article source: http://www.hse.gov.uk/research/rrhtm/rr1043.htm