Synthetic Metalworking Fluids Research Articles

Exposure to Metalworking Fluids and Cancer Incidence in the United Auto Workers-General Motors Cohort.

In previous studies, investigators have reported increased risks of specific cancers associated with exposure to metalworking fluids (MWFs). In this report we broadly examine the incidence of 14 types of cancer, with a focus on digestive, respiratory, and hormonal cancers, in the United Auto Workers-General Motors (UAW-GM) cohort, a cohort of workers exposed to MWFs (1973-2015). The cohort included 39,132 workers followed for cancer incidence. Cox models yielded estimates of adjusted hazard ratios, with categorical variables for lagged cumulative exposure to 3 types of MWF (straight, soluble, and synthetic). We fitted penalized splines to examine the shape of the exposure-response relationships. There were 7,809 incident cancer cases of interest. Oil-based straight and soluble MWFs were each modestly associated with all cancers combined. Exposure-response patterns were consistent with prior reports from this cohort, and results for splined exposures generally reflected their categorically modeled counterparts. We found significantly increased incidence of stomach and kidney cancer with higher levels of straight MWF exposure and increased rectal and prostate cancer with increasing water-based synthetic MWF exposure. Only non-Hodgkin lymphoma and prostate cancer were associated with soluble MWF. All results for colon and lung cancers were null. Our results provide updated evidence for associations between MWF exposure and incidence of several types of cancer.

Sustainable Lubrication/Cooling Systems for Efficient Turning Operations of γ-TiAl Parts from the Aeronautic Industry

This paper presents the study of the finishing, repair, and maintenance turning operations of gamma titanium aluminide (γ-TiAl) parts from the aeronautic industry, with the aim to evaluate different sustainable lubrication/cooling environments, including a newly developed synthetic ester water-based metalworking fluid (EcoMWF) to replace mineral-based MWF (MWF). The systems considered in this work are dry, cold-compressed air, minimum quantity lubrication (MQL), cryogenic, and flood on turning of a new and relatively low explored titanium alloy, γ-TiAl. Therefore, the influence of machining parameters and insert type on tool wear, surface roughness, roundness, and cutting temperature have been investigated for each environment. Results detailed in this study showed a significant influence of the lubrication/cooling systems on the machinability of γ-TiAl. The study also revealed that the sustainability of turning γ-TiAl could be improved under the cryogenic system and the new EcoMWF, keeping the same machining performance as common mineral-based MWF.Graphical abstract

Metalworking Fluid Exposure and Stroke Mortality Among US Autoworkers.

Although air pollution is an important risk factor for stroke, few studies have considered the impact of workplace exposure to particulate matter (PM). We examined implications of exposure to PM composed of metalworking fluids (MWFs) for stroke mortality in the United Autoworkers-General Motors cohort. Cox proportional hazards models with age as the timescale were used to estimate the association of cumulative straight, soluble, and synthetic MWF exposure with stroke mortality, controlling for sex, race, plant, calendar year, and hire year. Among 38,553 autoworkers followed during 1941-1995, we identified 114 ischemic stroke deaths and 113 hemorrhagic stroke deaths. Overall stroke mortality risk was increased among workers in the middle exposure category for straight MWF (hazard ratio (HR) = 1.31, 95% confidence interval (CI): 0.87, 1.98) and workers in the highest exposure category for synthetic MWF (HR = 1.94, 95% CI: 1.13, 3.16) compared with workers who had no direct exposure. Ischemic stroke mortality risk was increased among workers in the highest exposure categories for straight MWF (HR = 1.45, 95% CI: 0.83, 2.52) and synthetic MWF (HR = 2.39, 95% CI: 1.39, 4.50). We observed no clear relationship between MWF exposure and hemorrhagic stroke mortality. Our results support a potentially important role for occupational PM exposures in stroke mortality and indicate the need for further studies of PM exposure and stroke in varied occupational settings.

Adapting Decision Rules to Estimate Occupational Metalworking Fluid Exposure in a Case-Control Study of Bladder Cancer in Spain.

We adapted previously developed decision rules from the New England Bladder Cancer Study (NEBCS) to assign occupational exposure to straight, soluble, and synthetic metalworking fluids (MWFs) to participants of the Spanish Bladder Cancer Study (SBCS). The SBCS and NEBCS are case-control studies that used the same lifetime occupational history and job module questionnaires. We adapted published decision rules from the NEBCS that linked questionnaire responses to estimates of the probability (<5, ≥5 to <50, ≥50 to <100, and 100%), frequency (in h week-1), and intensity (in mg m-3) of exposure to each of the three broad classes of MWFs to assign exposure to 10 182 reported jobs in the SBCS. The decision rules used the participant's module responses to MWF questions wherever possible. We then used these SBCS module responses to calculate job-, industry-, and time-specific patterns in the prevalence and frequency of MWF exposure. These estimates replaced the NEBCS-specific estimates in decision rules applied to jobs without MWF module responses. Intensity estimates were predicted using a previously developed statistical model that used the decade, industry (three categories), operation (grinding versus machining), and MWF type extracted from the SBCS questionnaire responses. We also developed new decision rules to assess mineral oil exposure from non-machining sources (possibly exposed versus not exposed). The decision rules for MWF and mineral oil identified questionnaire response patterns that required job-by-job expert review. To assign MWF exposure, we applied decision rules that incorporated participant's responses and job group patterns for 99% of the jobs and conducted expert review of the remaining 1% (145) jobs. Overall, 14% of the jobs were assessed as having ≥5% probability of exposure to at least one of the three MWFs. Probability of exposure of ≥50% to soluble, straight, and synthetic MWFs was identified in 2.5, 1.7, and 0.5% of the jobs, respectively. To assign mineral oil from non-machining sources, we used module responses for 49% of jobs, a job-exposure matrix for 41% of jobs, and expert review for the remaining 10%. We identified 24% of jobs as possibly exposed to mineral oil from non-machining sources. We demonstrated that we could adapt existing decision rules to assess exposure in a new population by deriving population-specific job group patterns.

Metalworking Fluids and Colon Cancer Risk

Background:Metalworking fluids (MWFs) are a class of complex mixtures of chemicals and oils, including several known carcinogens that may pose a cancer hazard to millions of workers. Reports on the relation between MWFs and incident colon cancer have been mixed.Methods:We investigated the relation between exposure to straight, soluble, and synthetic MWFs and the incidence of colon cancer in a cohort of automobile manufacturing industry workers, adjusting for time-varying confounding affected by prior exposure to reduce healthy worker survivor bias. We used longitudinal targeted minimum loss-based estimation (TMLE) to estimate the difference in the cumulative incidence of colon cancer comparing counterfactual outcomes if always exposed above to always exposed below an exposure cutoff while at work. Exposure concentration cutoffs were selected a priori at the 90th percentile of total particulate matter for each fluid type: 0.034, 0.400, and 0.003 for straight, soluble, and synthetic MWFs, respectively.Results:The estimated 25-year risk differences were 3.8% (95% confidence interval [CI] = 0.7, 7.0) for straight, 1.3% (95% CI = −2.3, 4.8) for soluble, and 0.2% (95% CI = −3.3, 3.7) for synthetic MWFs, respectively. The corresponding risk ratios were 2.39 (1.12, 5.08), 1.43 (0.67, 3.04), and 1.08 (0.51, 2.30) for straight, soluble, and synthetic MWFs, respectively.Conclusions:By controlling for time-varying confounding affected by prior exposure, a key feature of occupational cohorts, we were able to provide evidence for a causal effect of straight MWF exposure on colon cancer risk that was not found using standard analytical techniques in previous reports.

The influence of modified vegetable oils on tool failure mode and wear mechanisms when turning AISI 1045

Abstract A newly developed bio-based metalworking fluid (MWF) from Jatropha oil is evaluated in this study as part of the research purposes for ‘greener’ machining activity. This work focuses on the machinability effects of using ionic liquids (ILs) added Jatropha-based MWFs of different weight concentrations (1, 5 and 10%). The machining performance on AISI 1045 steel was analyzed based on the lubrication effects of the novel modified Jatropha-based lubricants (MJO). Experimental results for the ILs added MJOs, depending on the ILs treat rate, were superior to the synthetic ester-based MWF. In addition, MJO + AIL10% outperformed all the other lubricant samples on cutting force and temperature, surface roughness, wear mechanisms and tool life of the uncoated cermet inserts during the machining process.

Modeling and simulation of colonization of water-based metalworking fluid by Mycobacterium immunogenum

The water-borne human pathogen Mycobacterium immunogenum (MI) originating from industrial wastewater contaminated with metalworking fluid (MWF), may pose serious public health risks. This warrants a front-of-the-pipe approach so as to control its growth in these fluids; this requires an understanding of its initial colonization process in pristine MWF. In this direction, using a synthetic MWF formulation, quadratic modeling of colonization was performed using response surface methodology (RSM) to understand parameter effects and interactions followed by in-silico simulation of optimal and inhibitory growth conditions using Genetic Algorithm (GA), and experimental validation. The experimental parameters that supported optimal growth of MI in culture included an alkaline pH (9.4) coupled with ambient temperature (30 °C), starter nutrient (OADC 2.028% v/v) and tramp oil (0.4% v/v.) Though OADC seemed to play an important role, tramp oil was found to be crucial for the colonization process. However, combinations of higher pH and lower temperature (∼23 °C) and lower pH and high temperature (∼37 °C) completely arrested the growth even in the presence of OADC and tramp oil. Collectively, the results provide critical information needed for achieving simulated laboratory culture of this pathogen for further research; this may facilitate development of novel biocide-independent strategies to effectively control this pathogen and its disposal-related hazards in aqueous streams.

Lung cancer mortality and exposure to synthetic metalworking fluid and biocides: controlling for the healthy worker survivor effect

ObjectivesSynthetic metalworking fluids (MWFs), widely used to cool and lubricate industrial machining and grinding operations, have been linked with increased risk of several cancers. Estimates of their relation with lung...

Metalworking Fluid Exposure and Consequences on Skin Health in a Metal Machining Factory: Review Article

Metalworking fluids (MWFs) are a variety of substances can be used during machining of metals such as cutting, turning, grinding, milling and drilling. National Institute of Occupational Safety and Health (NIOSH) in United States of America has stated that MWFs available in different forms such as straight oil (neat oil), soluble oil (emulsifiable oil), semisynthetic MWFs, and synthetic MWFs and during the machining processes worker can be exposed to MWFs through skin contact and inhalation. MWFs in machining factory allow significant bacterial growth in the fluids and aerosols which cause dermatological and respiratory adverse health effects among exposed workers. skin diseases that MWF exposure can cause various morphology of skin disorders such as skin scaling or dryness. Semi-quantitative dermal exposure assessment methods (DREAM) in both occupational and epidemiological survey. The prevention of the health effects of MWF on skin systems would probably by enhancing the awareness of the workers towards the health effects of MWF and the appropriate safety methods need to apply regularly all along their working time.

Breast Cancer Incidence and Exposure to Metalworking Fluid in a Cohort of Female Autoworkers.

Breast cancer is the leading cancer diagnosed among women, and environmental studies have produced few leads on modifiable risk factors for breast cancer. Following an Institute of Medicine recommendation for occupational studies of women highly exposed to potential breast cancer risk factors, we took advantage of an existing cohort of 4,503 female autoworkers in Michigan exposed to metalworking fluid (MWF), complex mixtures of oils and chemicals widely used in metal manufacturing worldwide. Cox proportional hazards models were fit to estimate hazard ratios for incident breast cancer (follow-up, 1985-2013) and cumulative exposure (20-year lag) to straight mineral oils (a known human carcinogen) and water-based soluble and synthetic MWF. Because the state cancer registry began decades after the cohort was defined, we restricted our analyses to subcohorts of women hired closer to the start of follow-up. Among those hired after 1969, the hazard ratio associated with a 1 interquartile-range increase in straight MWF exposure was 1.13 (95% confidence interval: 1.03, 1.23). In separate analyses of premenopausal breast cancer, defined by age at diagnosis, the hazard ratio was elevated for exposure to synthetic MWF (chemical lubricants with no oil content), possibly suggesting a different mechanism in the younger women with breast cancer. This study adds to the limited literature regarding quantitative chemical exposures and breast cancer risk.

Assessment of the healthy worker survivor effect in cancer studies of the United Autoworkers-General Motors cohort

ObjectiveThe healthy worker survivor effect (HWSE) can affect the validity of occupational studies when data are analysed incorrectly. HWSE depends on three underlying conditions: (1) leaving work predicts future exposure,...

Influence of minimal quantity lubrication (MQL) technique in achining evolution: A review and applications

Metal working fluids (MWFs) are one of the types of lubricants, which are extensively used in machining operations. Most of the MWFs are mineral oil based fluids. Due to their advantages, the consumption of MWFs is increasing in machining industry. Mineral, synthetic and semi-synthetic MWFs involve in the ecological cycle with air, soil and water and their toxicity effects damages the ecosystem. Vegetable oil lubricants are potential substitutes for mineral oil not only because they are renewable raw materials but also because they are biodegradable and non-toxic. Currently, there is a wide-scale evaluation of the use of metal working fluids (MWFs) in machining. Industries are looking for ways to reduce the amount of lubricants in metal removing operations due to the ecological and economical aspects. By implementing near-dry machining or a minimal quantity of lubrication (MQL), MWFs consumption can be reduced. The MQL technique involves the application of a small quantity of lubricant dispensed to the tool–work piece interface by compressed air flow. This paper gives a review on the mechanical performance of minimum quantity lubrication compared to completely dry and flood lubrication for various machining operations.

Estimation of the Probability of Exposure to Machining Fluids in a Population-Based Case-Control Study

We describe an approach for estimating the probability that study subjects were exposed to metalworking fluids (MWFs) in a population-based case-control study of bladder cancer. Study subject reports on the frequency of machining and use of specific MWFs (straight, soluble, and synthetic/semi-synthetic) were used to estimate exposure probability when available. Those reports also were used to develop estimates for job groups, which were then applied to jobs without MWF reports. Estimates using both cases and controls and controls only were developed. The prevalence of machining varied substantially across job groups (0.1–>0.9%), with the greatest percentage of jobs that machined being reported by machinists and tool and die workers. Reports of straight and soluble MWF use were fairly consistent across job groups (generally 50–70%). Synthetic MWF use was lower (13–45%). There was little difference in reports by cases and controls vs. controls only. Approximately, 1% of the entire study population was assessed as definitely exposed to straight or soluble fluids in contrast to 0.2% definitely exposed to synthetic/semi-synthetics. A comparison between the reported use of the MWFs and U.S. production levels found high correlations (r generally >0.7). Overall, the method described here is likely to have provided a systematic and reliable ranking that better reflects the variability of exposure to three types of MWFs than approaches applied in the past.[Supplementary materials are available for this article. Go to the publisher's online edition of Journal of Occupational and Environmental Hygiene for the following free supplemental resources: a list of keywords in the occupational histories that were used to link study subjects to the metalworking fluids (MWFs) modules; recommendations from the literature on selection of MWFs based on type of machining operation, the metal being machined and decade; popular additives to MWFs; the number and proportion of controls who reported various MWF responses by job group; the number and proportion of controls assigned to the MWF types by job group and exposure category; and the distribution of cases and controls assigned various levels of probability by MWF type.]

Skin absorption of six performance amines used in metalworking fluids.

Every year, 10 million workers are exposed to metalworking fluids (MWFs) that may be toxic. There are four types of MWFs: neat oils and three water-based MWFs (soluble oil, semisynthetic and synthetic), which are diluted with water and whose composition varies according to the mineral oils ratio. MWFs also contain various additives. To determine the absorption of six amines used as corrosion inhibitors and biocides in MWFs, porcine skin flow-through diffusion cell experiments were conducted with hydrophilic ethanolamines (mono-, di- and triethanolamine, MEA, DEA and TEA respectively) and a mixture of lipophilic amines (dibutylethanolamine, dicyclohexylamine and diphenylamine). The six amines were dosed in four vehicles (water and three generic water-based MWF formulations) and analyzed using a scintillation counter or gas chromatography/mass spectrometry. These 24 h studies showed that dermal absorption significantly (P < 0.05) increased from water for the six amines (e.g. 1.15 ± 0.29% dose; DEA in water) compared to other formulations (e.g. 0.13 ± 0.01% dose; DEA in semisynthetic MWF) and absorption was greatest for dibutylethanolamine in all the formulations. The soluble oil formulation tended to increase the dermal absorption of the hydrophilic amines. The permeability coefficient was significantly higher (P < 0.05) with TEA relative to the other hydrophilic amines (e.g. 4.22 × 10(-4) ± 0.53 × 10(-4) cm h(-1) [TEA in synthetic MWF] vs. 1.23 × 10(-4) ± 0.10 × 10(-4) cm h(-1) [MEA in synthetic MWF]), except for MEA in soluble oil formulation. Future research will confirm these findings in an in vivo pig model along with dermatotoxicity studies. These results should help MWF industries choose safer additives for their formulations to protect the health of metalworkers.

0224 Direct exposure to metalworking fluid aerosols and chronic obstructive pulmonary disease in a cohort of U.S. automotive industry workers

ObjectivesExposure to metalworking fluid (MWF) causes respiratory outcomes such as asthma and chronic bronchitis, as well as symptoms including phlegm and wheezing. Chronic obstructive pulmonary disease (COPD) encompasses these outcomes,...

0084 A Case-Control Study of Occupational Exposure to Metalworking Fluids and Bladder Cancer Risk among Men

ObjectivesMetalworking has been associated with bladder cancer risk in many studies. Metalworking fluids (MWFs) are suspected as the putative exposure, but epidemiologic data are limited. Based on state-of-the-art, quantitative exposure...

Extended tracking of the microbial community structure and dynamics in an industrial synthetic metalworking fluid system

Understanding of the occupational exposure risk scenario and disease etiology associated with industrial metalworking fluids (MWFs) requires knowledge of the development and composition of their microbial diversity in relation to the underlying fluid management factors. In this study, a managed synthetic MWF operation freshly recharged following the dumping, cleaning, and recharge (DCR) process was tracked in real time for microbial community changes over a period of 1.25 years (65 weeks). The recharged fluid developed very high bacterial counts (viable and nonviable) fairly quickly after the DCR process, indicating its inadequacy. Genus-/group-specific real-time qPCR confirmed the prevalence of six potentially pathogenic/immunogenic microbial genera/groups, viz. pseudomonads, enterics, mycobacteria, legionellae, actinomycetes, and fungi. Selective culturing revealed Acinetobacter and Bacillus as the most frequently isolated Gram-negative and Gram-positive genera, respectively, in addition to the presence of fungi and actinomycetes. Endotoxin perturbations (< 1000 to > 100000 EU mL⁻¹) coincided with temporal increases in Gram-negative bacteria and/or periodic biocide additions. PCR-DGGE-sequencing revealed an expanded estimated bacterial richness (up to 23 bands per sample). Of the 16 dominant bacterial phylotypes identified, the majority were detected for the first time in MWF. Interestingly, the study revealed a crucial role for MWF brand, among other fluid factors, in modulating the community structure and dynamics.

Metalworking fluid exposure and cancer risk in a retrospective cohort of female autoworkers

Metalworking fluids (MWFs) have been associated with cancer of several sites, but the risks have been primarily examined in men or in studies that adjusted for gender in analyses. To evaluate whether risks were similar in women, we report cancer mortality risk among 4,825 female autoworkers within the united autoworkers-general motors autoworkers cohort. Standardized mortality rates (SMRs) were calculated based on Michigan death rates (1980-2004). Internal comparisons (1941-2004) were examined using Cox regression for straight, soluble, and synthetic MWFs, and their corresponding oil- and water-based fractions. MWF exposure levels in the female cohort were generally less than two-third the MWF levels in the male cohort. Female autoworkers had an excess of cancer from all sites (SMR, 1.10; 95 % confidence interval (CI), 0.98-1.22) and lung cancer (SMR, 2.08; 95 % CI, 1.71-2.52). Colon cancer risk increased with straight (mineral oil) MWF exposure (exposure > median; hazard ratio = 3.1; 95 % CI, 1.2-8.0). A protective effect was observed for ovarian cancer with the soluble MWFs and water-based MWF metrics. Although bladder, rectal, and laryngeal cancers and malignant melanoma have been associated with straight MWF exposure and pancreatic cancer with synthetic MWF in men, there were too few deaths in this female subcohort to examine exposure-response relations for these sites. Results were null for lung and breast cancer. Our findings support an association between colon cancer and straight MWFs, but we found limited evidence of risk for other tumor sites at the lower exposure levels experienced by the female autoworkers.

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

Hypersensitivity pneumonitis, also known as "machine operator's lung" (MOL), has been related to microorganisms growing in metalworking fluids (MWFs), especially Mycobacterium immunogenum. We aimed to (i) describe the microbiological contamination of MWFs and (ii) look for chemical, physical, and environmental parameters associated with variations in microbiological profiles. We microbiologically analyzed 180 MWF samples from nonautomotive plants (e.g., screw-machining or metal-cutting plants) in the Franche-Comté region in eastern France and 165 samples from three French automotive plants in which cases of MOL had been proven. Our results revealed two types of microbial biomes: the first was from the nonautomotive industry, showed predominantly Gram-negative rods (GNR), and was associated with a low risk of MOL, and the second came from the automotive industry that was affected by cases of MOL and showed predominantly Gram-positive rods (GPR). Traces of M. immunogenum were sporadically detected in the first type, while it was highly prevalent in the automotive sector, with up to 38% of samples testing positive. The use of chromium, nickel, or iron was associated with growth of Gram-negative rods; conversely, growth of Gram-positive rods was associated with the absence of these metals. Synthetic MWFs were more frequently sterile than emulsions. Vegetable oil-based emulsions were associated with GNR, while mineral ones were associated with GPR. Our results suggest that metal types and the nature of MWF play a part in MWF contamination, and this work shall be followed by further in vitro simulation experiments on the kinetics of microbial populations, focusing on the phenomena of inhibition and synergy.

Risk of cervical cancer among female autoworkers exposed to metalworking fluids

Cervical cancer is caused by human papilloma virus (HPV). However, only a small proportion of women infected with HPV, progress to cervical cancer. Other co-factors must therefore be necessary to cause cervical cancer. We examined cervical cancer in relation to occupational exposure to metalworking fluids (MWF), which are complex mixtures containing several known carcinogens. A cohort of 4374 female autoworkers was followed from 1985-2004 for cancer diagnosis. Based on standardized incidence rates (SIR), we focused on cervical cancer in an internal analysis. Pooled logistic regression was used to model the relationship between exposure to three different types of MWF, selected constituents, and incidence of cervical cancer. Based on 40 cases, SIR were statistically significantly elevated for both race specific subgroups: 3.30 and 2.43, respectively for Caucasian and black women. The standard mortality ratio (SMR) was also statistically significantly elevated for Caucasian women (3.44) based on seven observed deaths. There was no association with oil-based straight fluid. Relative risks for soluble and synthetic MWF and nitrosamines were modestly elevated but not statistically significant. Water-based MWF may play a role in the etiology of cervical cancer. Further studies in larger cohorts of women are needed to clearly establish this relationship.