Systematic review of respiratory outbreaks associated with exposure to water-based metalworking fluids

DNA damage in workers exposed to mineral oils

Mineral oils, untreated or mildly treated, have been classified in group 1 as a potential source of cancer by the International Agency for Research on Cancer (IARC). Although numerous studies have implicated metalworking fluids (MWFs) as human carcinogens, toxicology data regarding the mechanism of carcinogenicity are limited. This study is intended to examine the systemic effects of machining workers' exposure to MWFs. The potential toxicity of mineral oils was investigated in 65 lathe workers compared to controls (66 men). The occupational exposure was measured by the National Institute for Occupational Safety and Health (NIOSH) 5026. The DNA damage has been examined by the comet assay method. According to the field assessments, the time-weighted average (TWA) exposure to mineral oil mist was 7.67 ± 3.21 mg/m3. A comet assay of peripheral blood cells showed that tail length (TL) and olive moment (OM) were significantly higher in the exposed group (p < 0.05). A multiple logistic regression analysis revealed that, within subjects with over 10 years of exposure, the odds ratio of worker with high TL, percent of DNA in tail, OM, and tail moment (TM) were 1.68, 1.41, 1.71, and 2.71, respectively. DNA strand break in exposed workers was associated with higher exposure time in years. Mineral oil toxicity could be altered in the presence of by-products and impurities. For a better understanding of genotoxicity, further studies are required.

Characterization of occupational inhalation exposures to particulate and gaseous straight and water-based metalworking fluids

Exposure assessments to metalworking fluids (MWF) is difficult considering the complex nature of MWF. This study describes a comprehensive exposure assessment to straight and water-based MWFs among workers from 20 workshops. Metal and organic carbon (OC) content in new and used MWF were determined. Full-shift air samples of inhalable particulate and gaseous fraction were collected and analysed gravimetrically and for metals, OC, and aldehydes. Exposure determinants were ascertained through observations and interviews with workers. Determinants associated with personal inhalable particulate and gaseous fractions were systematically identified using mixed models. Similar inhalable particle exposure was observed for straight and water-based MWFs (64-386 µg/m3). The gaseous fraction was the most important contributor to the total mass fraction for both straight (322-2362 µg/m3) and water-based MWFs (101-699 µg/m3). The aerosolized particles exhibited low metal content irrespective of the MWF type; however, notable concentrations were observed in the sumps potentially reaching hazardous concentrations. Job activity clusters were important determinants for both exposure to particulate and gaseous fractions from straight MWF. Current machine enclosures remain an efficient determinant to reduce particulate MWF but were inefficient for the gaseous fraction. Properly managed water-based MWF meaning no recycling and no contamination from hydraulic fluids minimizes gaseous exposure. Workshop temperature also influenced the mass fractions. These findings suggest that exposures may be improved with control measures that reduce the gaseous fraction and proper management of MWF.

A cluster of hypersensitivity pneumonitis associated with exposure to metalworking fluids

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/m³ 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.

Identification and Remediation of Environmental Exposures in Patients With Interstitial Lung Disease: Evidence Review and Practical Considerations

A relationship between inhalational exposure to materials in the environment and development of interstitial lung disease (ILD) is long recognized. Hypersensitivity pneumonitis is an environmentally -induced diffuse parenchymal lung disease. In addition to hypersensitivity pneumonitis, domestic and occupational exposures have been shown to influence onset and progression of other ILDs, including idiopathic interstitial pneumonias such as idiopathic pulmonary fibrosis. A key component of the clinical evaluation of patients presenting with ILD includes elucidation of a complete exposure history, which may influence diagnostic classification of the ILD as well as its management. Currently, there is no standardized approach to environmental evaluation or remediation of potentially harmful exposures in home or workplace environments for patients with ILD. This review discusses evidence for environmental contributions to ILD pathogenesis and draws on asthma and occupational medicine literature to frame the potential utility of a professional evaluation for environmental factors contributing to the development and progression of ILD. Although several reports suggest benefits of environmental assessment for those with asthma or certain occupational exposures, lack of information about benefits in broader populations may limit application. Determining the feasibility, long-term outcomes, and cost-effectiveness of environmental evaluation and remediation in acute and chronic ILDs should be a focus of future research.

Evidence for Environmental-Human Microbiota Transfer at a Manufacturing Facility with Novel Work-related Respiratory Disease

Rationale: Workers' exposure to metalworking fluid (MWF) has been associated with respiratory disease.Objectives: As part of a public health investigation of a manufacturing facility, we performed a cross-sectional study using paired environmental and human sampling to evaluate the cross-pollination of microbes between the environment and the host and possible effects on lung pathology present among workers.Methods: Workplace environmental microbiota were evaluated in air and MWF samples. Human microbiota were evaluated in lung tissue samples from workers with respiratory symptoms found to have lymphocytic bronchiolitis and alveolar ductitis with B-cell follicles and emphysema, in lung tissue samples from control subjects, and in skin, nasal, and oral samples from 302 workers from different areas of the facility. In vitro effects of MWF exposure on murine B cells were assessed.Measurements and Main Results: An increased similarity of microbial composition was found between MWF samples and lung tissue samples of case workers compared with control subjects. Among workers in different locations within the facility, those that worked in the machine shop area had skin, nasal, and oral microbiota more closely related to the microbiota present in the MWF samples. Lung samples from four index cases and skin and nasal samples from workers in the machine shop area were enriched with Pseudomonas, the dominant taxa in MWF. Exposure to used MWF stimulated murine B-cell proliferation in vitro, a hallmark cell subtype found in the pathology of index cases.Conclusions: Evaluation of a manufacturing facility with a cluster of workers with respiratory disease supports cross-pollination of microbes from MWF to humans and suggests the potential for exposure to these microbes to be a health hazard.

Ways to improve biocides for metalworking fluid

Metalworking fluids (MWF) are mainly emulsions of oil in water containing additives such as corrosion inhibitors, emulsifiers, defoamers, and biocides. Microbial contamination of MWF is almost systematic, and some of their constituents serve as nutrients for contaminating microorganisms. Biocides for MWF are protection products used to counter microbial contaminations and growth. Ideally, a biocide for MWF should have the following non-exhaustive criteria: have a broad-spectrum activity, be usable at low concentrations, be compatible with the formulation and the physical-chemical properties of MWF, be stable over time, retain its effectiveness in the presence of soiling, have no corrosive action on metals, present no danger to humans and the environment, be inexpensive. The future lies in the development of new molecules with biocidal activity corresponding to these ideal specifications, but in the meantime, it is possible to improve the performance of existing molecules currently on the market. Different strategies for potentiation of the activity of existing biocides are possible. The compatibility of the potentiation strategies with their use in metal working fluids is discussed.

Microbial contamination in water-based metalworking fluid as trigger for occupational hypersensitivity pneumonitis - development of specific IgG tools for a suspected clinical case

Microbially contaminated metal-working fluid (MWF) can cause respiratory symptoms in exposed workers in the form of exogenous allergic alveolitis/hypersensitivity pneumonitis (HP). The diagnosis of HP is based, among others, on the identification of the culprit and the detection of corresponding specific IgG antibodies (sIgG) in the patient's serum. Commercial antigen tools for the detection of these HP triggers are rarely available; therefore, antigens from contaminated MWF workplace samples were isolated exemplarily for diagnosis of a suspected HP case. Various MWF-specific bacteria were identified in the workplace samples, including Pseudomonas oleovorans, Pseudomonas alcaliphila, Pseudomonas spec., Paenibacillus glucanolyticus, and Corynebacterium amycolatum. The sIgG antigen binding, detected by ImmunoCAP system against MWF antigens from workplace samples and against the identified bacterial antigens, was much stronger in the patient serum compared to selected reference sera. The highest sIgG concentrations in the patient's serum could be determined against Pseudomonas antigens. Inhibition tests showed cross-reactions of MWF and Pseudomonas antigens, whereby the Pseudomonas antigens cross-reacted less with each other. For in-vitro diagnosis in case of suspected HP caused by contaminated MWF, workplace-related antigens are now available.

Work-related adverse respiratory health outcomes at a machine manufacturing facility with a cluster of bronchiolitis, alveolar ductitis and emphysema (BADE)

OBJECTIVES

Four machine manufacturing facility workers had a novel occupational lung disease of uncertain aetiology characterised by lymphocytic bronchiolitis, alveolar ductitis and emphysema (BADE). We aimed to evaluate current workers' respiratory health in relation to job category and relative exposure to endotoxin, which is aerosolised from in-use metalworking fluid.

METHODS

We offered a questionnaire and spirometry at baseline and 3.5 year follow-up. Endotoxin exposures were quantified for 16 production and non-production job groups. Forced expiratory volume in one second (FEV₁) decline ≥10% was considered excessive. We examined SMRs compared with US adults, adjusted prevalence ratios (aPRs) for health outcomes by endotoxin exposure tertiles and predictors of excessive FEV₁ decline.

RESULTS

Among 388 (89%) baseline participants, SMRs were elevated for wheeze (2.5 (95% CI 2.1 to 3.0)), but not obstruction (0.5 (95% CI 0.3 to 1.1)). Mean endotoxin exposures (range: 0.09-28.4 EU/m³) were highest for machine shop jobs. Higher exposure was associated with exertional dyspnea (aPR=2.8 (95% CI 1.4 to 5.7)), but not lung function. Of 250 (64%) follow-up participants, 11 (4%) had excessive FEV₁ decline (range: 403-2074 mL); 10 worked in production. Wheeze (aPR=3.6 (95% CI 1.1 to 12.1)) and medium (1.3-7.5 EU/m³) endotoxin exposure (aPR=10.5 (95% CI 1.3 to 83.1)) at baseline were associated with excessive decline. One production worker with excessive decline had BADE on subsequent lung biopsy.

CONCLUSIONS

Lung function loss and BADE were associated with production work. Relationships with relative endotoxin exposure indicate work-related adverse respiratory health outcomes beyond the sentinel disease cluster, including an incident BADE case. Until causative factors and effective preventive strategies for BADE are determined, exposure minimisation and medical surveillance of affected workforces are recommended.

Severe lung disease characterized by lymphocytic bronchiolitis, alveolar ductitis, and emphysema (BADE) in industrial machine-manufacturing workers

BACKGROUND

A cluster of severe lung disease occurred at a manufacturing facility making industrial machines. We aimed to describe disease features and workplace exposures.

METHODS

Clinical, functional, radiologic, and histopathologic features were characterized. Airborne concentrations of thoracic aerosol, metalworking fluid, endotoxin, metals, and volatile organic compounds were measured. Facility airflow was assessed using tracer gas. Process fluids were examined using culture, polymerase chain reaction, and 16S ribosomal RNA sequencing.

RESULTS

Five previously healthy male never-smokers, ages 27 to 50, developed chest symptoms from 1995 to 2012 while working in the facility's production areas. Patients had an insidious onset of cough, wheeze, and exertional dyspnea; airflow obstruction (mean FEV₁  = 44% predicted) and reduced diffusing capacity (mean = 53% predicted); and radiologic centrilobular emphysema. Lung tissue demonstrated a unique pattern of bronchiolitis and alveolar ductitis with B-cell follicles lacking germinal centers, and significant emphysema for never-smokers. All had chronic dyspnea, three had a progressive functional decline, and one underwent lung transplantation. Patients reported no unusual nonoccupational exposures. No cases were identified among nonproduction workers or in the community. Endotoxin concentrations were elevated in two air samples; otherwise, exposures were below occupational limits. Air flowed from areas where machining occurred to other production areas. Metalworking fluid primarily grew Pseudomonas pseudoalcaligenes and lacked mycobacterial DNA, but 16S analysis revealed more complex bacterial communities.

CONCLUSION

This cluster indicates a previously unrecognized occupational lung disease of yet uncertain etiology that should be considered in manufacturing workers (particularly never-smokers) with airflow obstruction and centrilobular emphysema. Investigation of additional cases in other settings could clarify the cause and guide prevention.

Risk Assessment for Metalworking Fluids and Respiratory Outcomes

Background

Metalworking fluids (MWFs) are mixtures with inhalation exposures as mists, dusts, and vapors, and dermal exposure in the dispersed and bulk liquid phase. A quantitative risk assessment was performed for exposure to MWF and respiratory disease.

Methods

Risks associated with MWF were derived from published studies and NIOSH Health Hazard Evaluations, and lifetime risks were calculated. The outcomes analyzed included adult onset asthma, hypersensitivity pneumonitis, pulmonary function impairment, and reported symptoms. Incidence rates were compiled or estimated, and annual proportional loss of respiratory capacity was derived from cross-sectional assessments.

Results

A strong healthy worker survivor effect was present. New-onset asthma and hypersensitivity pneumonitis, at 0.1 mg/m³ MWF under continuous outbreak conditions, had a lifetime risk of 45%; if the associated microbiological conditions occur with only 5% prevalence, then the lifetime risk would be about 3%. At 0.1 mg/m³, the estimate of excess lifetime risk of attributable pulmonary impairment was 0.25%, which may have been underestimated by a factor of 5 or more by a strong healthy worker survivor effect. The symptom prevalence associated with respiratory impairment at 0.1 mg/m³ MWF was estimated to be 5% (published studies) and 21% (Health Hazard Evaluations).

Conclusion

Significant risks of impairment and chronic disease occurred at 0.1 mg/m³ for MWFs in use mostly before 2000. Evolving MWFs contain new ingredients with uncharacterized long-term hazards.

Risk assessment for metalworking fluids and cancer outcomes

BACKGROUND

Metalworking fluids (MWF) are complex mixtures with dermal and inhalation exposure. Published reports reveal excess cancer risk.

METHODS

Using published findings exposure response was derived for each attributable cancer site. Aggregate excess lifetime risk was estimated by applying a lifetable calculation.

RESULTS

Cancer sites contributing the most attributable cases were larynx, esophagus, brain, female breast, and uterine cervix. With constant workplace MWF exposure of 0.1 mg/m³ over a 45 years working life, the risk of attributable cancer was 3.7% or, excluding the less certain female cancers, 3.1%.

CONCLUSION

Substantial cancer risks occurred at 0.1 mg/m³ MWF, one fourth of the current NIOSH recommended exposure limit for MWF total particulate. Because ingredients in current MWF remain from earlier formulations, it is likely that some MWF carcinogenicity persists today. Although important changes have occurred, newer agents are being continually introduced with little or no knowledge of chronic health risks.

Hypersensitivity Pneumonitis Due to Metalworking Fluid Aerosols

PURPOSE OF REVIEW

This review summarises the clinical knowledge of hypersensitivity pneumonitis in workers exposed to aerosols of metalworking fluid, reviewing published outbreaks and clinical cases.

RECENT FINDINGS

Metalworking fluid exposure has become the commonest recognised cause of occupational hypersensitivity pneumonitis, having been rare before 2000. There are many possible agents in the metalworking fluid which may be the cause of disease including bacteria, mycobacteria, fungae, biocides, emulsifiers, reodorants and dissolved chrome and cobalt. Causes are likely to be different in different outbreaks. Mycobacteria growing in the metalworking fluid have generated immune responses in some workers, but their role in disease causation is not yet established. Many outbreaks have been identified in large workplaces using common sumps. It is not possible to prevent microbial contamination of metalworking fluids in use. Disease prevention should focus on stopping inhalation of aerosols, particularly by re-engineering to remove recirculation.

Early immunopathological events in acute model of mycobacterial hypersensitivity pneumonitis in mice

Prolonged exposure to antigens of non-tuberculous mycobacteria species colonizing industrial metalworking fluid (MWF), particularly Mycobacterium immunogenum (MI), has been implicated in chronic forms of hypersensitivity pneumonitis (HP) in machinists based on epidemiology studies and long-term exposure of mouse models. However, a role of short-term acute exposure to these antigens has not been described in the context of acute forms of HP. This study investigated short-term acute exposure of mice to MI cell lysate (or live cell suspension) via oropharyngeal aspiration. The results showed there was a dose- and time-dependent increase (peaking at 2 h post-instillation) in lung immunological responses in terms of the pro- (TNFα, IL-6, IL-1β) and anti-inflammatory (IL-10) cytokines. Bronchoalveolar lavage and histology showed neutrophils as the predominant infiltrating cell type, with lymphocytes <5% at all timepoints or concentrations. Granulomatous inflammation peaked between 8 and 24 h post-exposure, and resolved by 96 h. Live bacterial challenge, typically encountered in real-world exposures, showed no significant differences from bacterial lysate except for induction of appreciable levels of interferon (IFN)-γ, implying additional immunogenic potential. Collectively, the short-term mycobacterial challenge in mice led to a transient early immunopathologic response, with little adaptive immunity, which is consistent with events associated with human acute forms of HP. Screening of MWF-originated mycobacterial genotypes/variants (six of MI, four of M. chelonae, two of M. abscessus) showed both inter- and intra-species differences, with MI genotype MJY10 being the most immunogenic. In conclusion, this study characterized the first short-term mycobacterial exposure mouse model that mimics acute HP in machinists; this could serve as a potentially useful model for rapid screening of field MWF-associated mycobacteria for routine and timely occupational risk assessment and for investigating early biomarkers and mechanisms of this understudied immune lung disease.

Epidemiology of occupational hypersensitivity pneumonitis; reports from the SWORD scheme in the UK from 1996 to 2015

Objective

To estimate the reported incidence of occupational hypersensitivity pneumonitis (OHP) in the UK and to consider whether the pattern of attributed causation has changed over time.

Methods

All cases of OHP reported to the SWORD scheme between January 1996 and December 2015 were classified into 1 of 10 categories of the suspected agent. Cases were grouped into four 5-year time periods to examine any changing pattern in incidence or suspected causation. For each time period, the annual incidence was calculated using the estimated number of reported cases and the working population of the UK.

Results

Between 1996 and 2015, there were 202 actual cases of OHP reported to SWORD, equating to an estimated 818 cases, when adjusting for the sampling ratio. Over this period, the annual UK incidence was 1.4 per million workers. The mean (SD) age of reported cases was 52 (13) years, and cases were four-times more likely to be men than women. Over the study period, there was a fall in the proportion of cases reported to be due to agricultural exposures (44–12%), and an increase in cases due to metalworking fluids (MWFs, 2–45%).

Conclusions

Over the last 20 years, the incidence of OHP in the UK has been ∼1–2 cases per million workers per year. Working with water-based MWFs is now the most commonly suspected causative exposure for OHP cases reported to the SWORD scheme in the UK.

Investigating a persistent odor at an aircraft seat manufacturer

An aircraft seat manufacturing company requested a NIOSH health hazard evaluation to help identify a strong odor that had persisted throughout the facility for over a year. Employees reported experiencing health effects thought to be related to the odor. We collected and analyzed area air samples for volatile organic compounds, endotoxin, bacterial and fungal metagenome, and metalworking fluid aerosol. Bulk metalworking fluid samples were analyzed for endotoxin, bacterial and fungal metagenome, and viable bacteria and fungus. We also evaluated the building ventilation systems and water diversion systems. Employees underwent confidential medical interviews about work practices, medical history, and health concerns. Based on our analyses, the odor was likely 2-methoxy-3,5-dimethylpyrazine. This pyrazine was found in air samples across the facility and originated from bacteria in the metalworking fluid. We did not identify bacteria known to produce the compound but bacteria from the same Proteobacteria order were found as well as bacteria from orders known to produce other pyrazines. Chemical and biological contaminants and odors could have contributed to health symptoms reported by employees, but it is likely that the symptoms were caused by several factors. We provided several recommendations to eliminate the odor including washing and disinfecting the metalworking machines and metalworking fluid recycling equipment, discarding all used metalworking fluid, instituting a metalworking fluid maintenance program at the site, and physically isolating the metalworking department from other departments.

Endotoxin in Size-Separated Metal Working Fluid Aerosol Particles

Patients with airway symptoms working in metal working industries are increasing, despite efforts to improve the environmental air surrounding the machines. Our aim was to analyse the amount of endotoxin in size-separated airborne particles of metal working fluid (MWF) aerosol, by using the personal sampler Sioutas cascade impactor, to compare filter types, and to compare the concentration of airborne endotoxin to that of the corresponding MWFs. In a pilot field study, aerosols were collected in two separate machine halls on totally 10 occasions, using glass fibre and polytetrafluoroethylene (PTFE) filters in parallel at each station. Airborne endotoxin was distributed over all size fractions. While a major part was found in the largest size fraction (72%, 2.5-10 µm), up to 8% of the airborne endotoxin was detected in the smallest size fraction (<0.25 µm). Comparing the efficiency of the filter types, a significantly higher median endotoxin level was found with glass fibres filters collecting the largest particle-size fraction (1.2-fold) and with PTFE filters collecting the smallest ones (5-fold). The levels of endotoxin in the size-separated airborne particle fractions correlated to those of the MWFs supporting the aerosol-generating machines. Our study indicates that a significant part of inhalable aerosols of MWFs consists of endotoxin-containing particles below the size of intact bacteria, and thus small enough to readily reach the deepest part of the lung. Combined with other chemical irritants of the MWF, exposure to MWF aerosols containing endotoxin pose a risk to respiratory health problems.

Occupational hypersensitivity pneumonitis: an EAACI position paper

The aim of this document was to provide a critical review of the current knowledge on hypersensitivity pneumonitis caused by the occupational environment and to propose practical guidance for the diagnosis and management of this condition. Occupational hypersensitivity pneumonitis (OHP) is an immunologic lung disease resulting from lymphocytic and frequently granulomatous inflammation of the peripheral airways, alveoli, and surrounding interstitial tissue which develops as the result of a non-IgE-mediated allergic reaction to a variety of organic materials or low molecular weight agents that are present in the workplace. The offending agents can be classified into six broad categories that include bacteria, fungi, animal proteins, plant proteins, low molecular weight chemicals, and metals. The diagnosis of OHP requires a multidisciplinary approach and relies on a combination of diagnostic tests to ascertain the work relatedness of the disease. Both the clinical and the occupational history are keys to the diagnosis and often will lead to the initial suspicion. Diagnostic criteria adapted to OHP are proposed. The cornerstone of treatment is early removal from exposure to the eliciting antigen, although the disease may show an adverse outcome even after avoidance of exposure to the causal agent.

Hypersensitivity pneumonitis in workers exposed to metalworking fluids

Background

This study used data from a large UK outbreak investigation, to develop and validate a new case definition for hypersensitivity pneumonitis due to metalworking fluid exposure (MWF-HP).

Methods

The clinical data from all workers with suspected MWF-HP were reviewed by an experienced panel of clinicians. A new MWF-HP Score was then developed to match the “gold standard” clinical opinion as closely as possible, using standard diagnostic criteria that were relatively weighted by their positive predictive value.

Results

The new case definition was reproducible, and agreed with expert panel opinion in 30/37 cases. This level of agreement was greater than with any of the three previously utilized case definitions (agreement in 16–24 cases). Where it was possible to calculate, the MWF-HP Score also performed well when applied to 50 unrelated MWF-HP cases.

Conclusions

The MWF-HP Score offers a new case definition for use in future outbreaks. Am. J. Ind. Med. 57:872–880, 2014. © 2014 The Authors. American Journal of Industrial Medicine Published by Wiley Periodicals, Inc.

Investigation of respiratory and dermal symptoms associated with metal working fluids at an aircraft engine manufacturing facility

BACKGROUND

Each year, 1.2 million metalworkers are exposed to metalworking fluids (MWFs), which can cause dermal and respiratory disease. The National Institute for Occupational Safety and Health (NIOSH) conducted a health hazard evaluation of MWF exposures at an aircraft engine manufacturing facility. The objectives were to determine employee exposures to endotoxin and MWFs in the air, characterize symptoms experienced by employees working with MWFs, compare them to symptoms of employees unexposed to MWFs, and make recommendations for reducing exposures based on results.

METHODS

Four hundred seven workers were categorized as MWF exposed or MWF unexposed and completed questionnaires. Estimated prevalence ratios (PR) of dermatitis, asthma, and work-related asthma (WRA) symptoms were calculated. Airborne concentrations of MWF and endotoxin were measured, and work practices observed.

RESULTS

MWF exposed workers had a significantly higher prevalence of dermatitis on wrists/forearms (PR 2.59; 95% CI 1.22, 5.46), asthma symptoms (PR 1.49; 95% CI 1.05, 2.13), and WRA symptoms (PR 2.10; 95% CI 1.22, 3.30) than unexposed workers. Airborne concentrations of MWF were below the NIOSH recommended exposure limit (REL) for MWF aerosols (thoracic particulate mass).

CONCLUSIONS

Despite MWF exposures below the NIOSH REL, exposed workers had a higher prevalence of asthma, WRA, and dermatitis symptoms than unexposed workers. Recommendations to reduce exposure included configuring mist collectors to automatically turn on when the machine is in use, and enforcing enclosure use.

New occupational and environmental causes of asthma and extrinsic allergic alveolitis

Asthma and extrinsic allergic alveolitis (EAA) remain prevalent respiratory diseases and the cause of a significant disease burden. This article reviews the recent occupational and environmental causes described for these conditions. Even over the limited time spam addressed by this article, novel agents and new data relating to already suggested causes have been described. Various types of work tasks or exposures are described that appear to cause both asthma and EAA. Isocyanates, the best example of dual potential to cause asthma and EAA are discussed, as is the new understanding of the role metal-working fluids play when causing respiratory diseases.

Microorganisms in metalworking fluids: current issues in research and management

The microbial contamination of water miscible metalworking fluids (MWFs) is a serious problem in metal industry. A good maintenance of MWF re-circulation systems can extend the lifetime of coolants and ensure the quality of the tools produced. In MWFs, as in the other water-based environments, microorganisms usually live in the form of biofilms, the communities of bacteria and fungi attached to the surface of sumps, metal parts and also to each other. Biofilms exhibit very high resistance to biocides. The effect of biocides that are used as additives to MWFs to control the growth of the bacterial and fungal microbiomes (microorganisms characteristic to the individual coolant system) have become the subject of research only in recent years. There are also only sparse reports on the impact of biocides on microorganisms growing in biofilms in MWF installations. Fast growing mycobacteria are important members of these biofilm communities. Their presence has recently been linked with the occurrence of cases of hypersensitivity pneumonitis, a serious respiratory disorder in the metal industry employees. The new, relatively fast and inexpensive techniques to assess the species diversity within MWF microbiomes and their population size should be developed in order to control the microorganisms' proliferation in MWFs and to diminish the occupational exposure to harmful bioaerosols in metal industry.