A cluster of hypersensitivity pneumonitis associated with exposure to metalworking fluids

Abstract

Background: Workers exposed to metalworking fluids (MWF) can develop respiratory illnesses including hypersensitivity pneumonitis (HP). These respiratory manifestations are likely due to microbial contamination of aerosolized MWF. This paper reports a cluster of HP and respiratory symptoms at a manufacturing plant where MWF and workplace air were contaminated with bacterial endotoxin despite frequent negative bacterial cultures of MWF. Methods: A pulmonologist assessed and treated three workers with respiratory symptoms. The Occupational Safety and Health Administration (OSHA) inspected the plant. OSHA's investigation included bacterial culture of MWF, measurement of endotoxin concentrations in MWF and workplace air, review of the employer's fluid management program, and distribution of a cross-sectional symptom questionnaire.Results: Three workers had biopsy-confirmed HP. In addition, 30.8% of questionnaire respondents reported work-related respiratory symptoms. OSHA detected endotoxin levels as high as 92,000 endotoxin units (EU)/ml in MWF and 3200 EU/m 3 in air. Endotoxin concentrations and risk of MWF inhalation were highest near an unenclosed multistation computer numerical control machine. A contractor had tested this machine's MWF for bacterial growth weekly during the preceding three years, and most (96.0%) of those tests were negative.Conclusions: Contaminated MWF can cause severe occupational lung disease even if microorganisms do not grow in fluid cultures. Endotoxin testing can increase the sensitivity of detection of microbial contamination. However, employers should not rely solely upon MWF testing data to protect workers. Medical surveillance and meticulous source control, such as engineering controls to suppress MWF mist and prevent its inhalation, can reduce the likelihood of respiratory disease.

Microbial Community Establishment, Succession, and Temporal Dynamics in an Industrial Semi-Synthetic Metalworking Fluid Operation: A 50-Week Real-Time Tracking

“…Over the years, it has been recognized that significant health and safety risks exist for machine workers exposed to microbially contaminated MWFs [ 18 , 19 , 20 , 21 , 22 , 23 , 24 , 25 , 26 , 67 , 68 , 69 , 70 , 71 ]. In terms of the etiology of health effects, while the infectivity of MWF microbes may be dependent on viability, the immunogenicity is independent of their viability status as non-viable cells may carry the causal antigens repertoire; hence, there is a need to determine the load of both viable as well as non-viable populations of the microbial community in the metalworking fluid.…”

“…SDA meant for the growth of fungi did not yield any fungal colonies from the first three DCR samples (before dump, neat, and non-circulated) and SS#1. However, fungal population was detected in the subsequent samples except SS#6, 7, 12,13,14,17,18,21,23,24,28,29,31,33,34, and 37 at levels varying from 1 to 3.25 × 10 3 cfu/mL. The typical fungal colonies were identified as N. haematococca based on ITS sequencing.…”

“…Occupational exposure to microbially contaminated MWFs has been associated with various cutaneous and respiratory illnesses such as asthma, hypersensitivity pneumonitis, bacterial pneumonia, among others [ 15 , 16 , 17 , 18 , 19 , 20 , 21 , 22 , 23 , 24 , 25 , 26 ]. Studies have implied cross-pollination of microbial agents between MWF and human cases of respiratory disease [ 19 , 23 ].…”

Novel occupational causes of hypersensitivity pneumonitis

“…James et al [51] used molecular techniques and phylogenetics to identify and measure microbial burden and described a close spatial relationship between nontuberculous mycobacteria and an outbreak of HP related to contamination of MWF, which had been recirculated via a common sump. Tustin et al [52] recently described 3 sentinel cases of HP from MWF and undertook a cross-sectional investigation that revealed a third of workers had work-related symptoms. There were high levels of endotoxin in MWF and air, which the authors inferred signified microbial contamination.…”