Clinical investigation of an outbreak of alveolitis and asthma in a car engine manufacturing plant

Abstract

Background: Exposure to metal working fluid (MWF) has been associated with outbreaks of extrinsic allergic alveolitis (EAA) in the USA, with bacterial contamination of MWF being a possible cause, but is uncommon in the UK. Twelve workers developed EAA in a car engine manufacturing plant in the UK, presenting clinically between December 2003 and May 2004. This paper reports the subsequent epidemiological investigation of the whole workforce. The study had three aims: (1) to measure the extent of the outbreak by identifying other workers who may have developed EAA or other work-related respiratory diseases; (2) to provide case detection so that those affected could be treated; and (3) to provide epidemiological data to identify the cause of the outbreak. Methods: The outbreak was investigated in a three-phase cross-sectional survey of the workforce. In phase I a respiratory screening questionnaire was completed by 808/836 workers (96.7%) in May 2004. In phase II 481 employees with at least one respiratory symptom on screening and 50 asymptomatic controls were invited for investigation at the factory in June 2004. This included a questionnaire, spirometry and clinical opinion. 454/481 (94.4%) responded and 48/50 (96%) controls. Workers were identified who needed further investigation and serial measurements of peak expiratory flow (PEF). In phase III 162 employees were seen at the Birmingham Occupational Lung Disease clinic. 198 employees returned PEF records, including 141 of the 162 who attended for clinical investigation. Case definitions for diagnoses were agreed. Results: 87 workers (10.4% of the workforce) met case definitions for occupational lung disease, comprising EAA (n = 19), occupational asthma (n = 74) and humidifier fever (n = 7). 12 workers had more than one diagnosis. The peak onset of work-related breathlessness was Spring 2003. The proportion of workers affected was higher for those using MWF from a large sump (27.3%) than for those working all over the manufacturing area (7.9%) (OR = 4.39, p,0.001). Two workers had positive specific provocation tests to the used but not the unused MWF solution. Conclusions: Extensive investigation of the outbreak of EAA detected a large number of affected workers, not only with EAA but also occupational asthma. This is the largest reported outbreak in Europe. Mist from used MWF is the likely cause. In workplaces using MWF there is a need to carry out risk assessments, to monitor and maintain fluid quality, to control mist and to carry out respiratory health surveillance.

Respiratory symptoms and conditions related to occupational exposures in machine shops

“…Previous studies focusing on specific workplaces, mainly in the automobile industry, have linked exposure to metalworking fluids with respiratory symptoms, lung function changes, and occupational asthma, bronchitis or allergic alveolitis (10)(11)(12)(13)(14)(15)(16)(17)(18)(19)(20). Most of these studies were conducted in North America.…”

Factors Influencing the Microbial Composition of Metalworking Fluids and Potential Implications for Machine Operator's Lung

“…Although asthma and dermatitis seem to be caused by the chemical toxicity of MWFs due to additional components (e.g., biocides, defoamers, corrosion inhibitors, or dyes) (22,33,38), MOL has been related to microorganisms that frequently contaminate MWFs, especially Mycobacterium immunogenum, a recently described, fast-growing mycobacterium included in the Mycobacterium chelonae-Mycobacterium abscessus complex (18,24,37,48,52,54). Arguments in favor of this etiology are the presence of specific precipitins in MWF-related HP cases (5,14,32) and/or the presence of M. immunogenum in their environment (4,18,42,52). The ability to induce HP in mice exposed intranasally to M. immunogenum (16,40) is evidence of the role of this microorganism.…”

Hypersensitivity pneumonitis and metalworking fluids contaminated by mycobacteria

“…Barber and colleagues evoke the elusive nature of the exact aetiology of MWF-HP whilst noting that, in the UK investigation at the Powertrain UK metalworking site (Birmingham, UK), it was not possible to culture any opportunistic mycobacteria or find any evidence of mycobacterial DNA by PCR of 125 MWF samples [2,4]. In our series, similarly to a number of US outbreaks, Mycobacterium immunogenum has been implicated as the cause of the MWF-HP.…”

“…It is widely recognised that cases of hypersensitivity pneumonitis (HP) occurring in metalworking fluids (MWFs) workers in the literature tend to be more often described in Europe [1,2]. In certain cases, difficulty in gaining access to the samples of some companies (related to the reluctance of employers) and the lack of knowledge of MWF-HP can also lead to underdiagnosis.…”