Comparative pulmonary toxicity of inhaled metalworking fluids in rats and mice

Cell toxicity assessment in co-treatment to metalworking fluids and vibration: an in vitro study of occupational exposure setting

This study was designed to study dual risk of MWFs and vibration according to exposure simulation of selected industry. Air samples of two types MWFs were evaluated according to NIOSH 5026. Vibration acceleration exposure was assessed based on the ISO 8041:2005 standard. Cell treatment of both MWF air samples and vibration as the same as dual exposure to MWF airborne and vibration was assessed. There is a potency of nitrosamine formation in airborne samples of ethylamine containing MWF, while heterocyclic including bore is found in airborne bore containing MWF. DNA breaks caused by boron-containing MWF were higher than nitrosamine air samples. Oxidative stress production and chronic inflammation were highlighted in the response to cell treatments. The risk of cell toxicity in machining workers was evaluated at a level lower than the occupational exposure limit for MWFs and vibration.

Prediction of size-selective permitted daily exposures for mineral oil mist based on an in vitro study in different scenarios

The incidence of DNA damage from exposure to specific types of metalworking fluids has been reported. In this research, size-selective permissible limits to prevent genotoxic damage in A549 cell lines exposed to two types of mineral oil were estimated for the first time using a benchmark dose approach and extrapolated to workers. The comet assay was performed based on Olive and Banath protocol to determine DNA damage. Then, the Benchmark Dose, the 95% lower bound confidence limit BMD, and the 95% upper-bound confidence limit BMD were determined using continuous response data. Finally, the four Benchmark Dose levels reported in the A549 cell line were extrapolated to the human population in occupational settings in two phases. This study showed when determining the permissible limits, the type used or unused, the type of injury, the organ affected in the body and the size of the particles should also be considered.

Release of Interleukin-1β evaluation among mineral oil mist–exposed workers

Exposure to aerosols has been found to be linked to respiratory impairment. Although the effects of both indoor and outdoor exposures to particulates have been extensively reported, exposures to mists are less studied. Herein, we reported a survey of mineral oil mist toxicity in an occupational exposure scenario. For the purpose of this study, 65 lathe workers of the metal processing industry, as mineral oil mist–exposed population, were studied. Thereafter, the participants’ age, smoking habits and work experience were matched with those of the control workers ( n = 65) who were not occupationally exposed to mist. Thereafter, air samples were evaluated from the breathing zone of the workers using NIOSH method 5026. Plasma Interleukin-1β as a pro-inflammatory indicator was assessed in all the studied subjects. Mean ± standard deviation of mineral oil mist time-weighted average exposure in lathe workers was 7.10± 3.49 mg/m3. IL-1β cytokine levels were significantly higher in the lathe groups compared to the control group. The mean level of Interleukin-1β in the control subjects (2922 pg/L) was selected as the cut-off point of the inflammation effect. Based on this pro-inflammatory point, the results of monitoring showed that 60% of the exposed were affected. A Spearman correlation was also found between mineral oil mist exposure and inflammation in the affected subjects. Our findings highlighted the immunological potential of mineral oil mist in occupational exposure. Overall, the results of this study suggested that Interleukin-1β evaluation in mineral oil mist exposure could be considered as both an acute and chronic inflammation marker.

Early Effect Markers and Exposure Determinants of Metalworking Fluids Among Metal Industry Workers: Protocol for a Field Study

Background

Exposure to aerosols from metalworking fluids (MWF) has previously been related to a series of adverse health outcomes (eg, cancer, respiratory diseases). Our present epidemiological study focuses on occupational exposures to MWF and a panel of exposure and effect biomarkers. We hypothesize that these health outcomes are caused by particle exposure that generates oxidative stress, leading to airway inflammation and ultimately to chronic respiratory diseases. We aimed to assess whether MWF exposure, in particular as characterized by its oxidative potential, is associated with biomarkers of oxidative stress and inflammation as well as genotoxic effects.

Objective

The ultimate goal is to develop exposure reduction strategies based on exposure determinants that best predict MWF-related health outcomes. The following relationships will be explored: (1) exposure determinants and measured exposure; (2) occupational exposure and preclinical and clinical effect markers; (3) exposure biomarkers and biomarkers of effect in both exhaled breath condensate and urine; and (4) biomarkers of effect, genotoxic effects and respiratory symptoms.

Methods

At least 90 workers from France and Switzerland (30 controls, 30 exposed to straight MWF and 30 to aqueous MWF) were followed over three consecutive days after a nonexposed period of at least two days. The exposure assessment is based on MWF, metal, aldehyde, and ultrafine particle number concentrations, as well as the intrinsic oxidative potential of aerosols. Furthermore, exposure biomarkers such as metals, metabolites of polycyclic aromatic hydrocarbons and nitrosamine are measured in exhaled breath condensate and urine. Oxidative stress biomarkers (malondialdehyde, 8-isoprostane, 8-hydroxy-2’-deoxyguanosine, nitrates, and nitrites) and exhaled nitric oxide, an airway inflammation marker, are repeatedly measured in exhaled breath condensate and urine. Genotoxic effects are assessed using the buccal micronucleus cytome assay. The statistical analyses will include modelling exposure as a function of exposure determinants, modelling the evolution of the biomarkers of exposure and effect as a function of the measured exposure, and modelling respiratory symptoms and genotoxic effects as a function of the assessed long-term exposure.

Results

Data collection, which occurred from January 2018 until June 2019, included 20 companies. At the date of writing, the study included 100 subjects and 29 nonoccupationally exposed controls.

Conclusions

This study is unique as it comprises human biological samples, questionnaires, and MWF exposure measurement. The biomarkers collected in our study are all noninvasive and are useful in monitoring MWF exposed workers. The aim is to develop preventative strategies based on exposure determinants related to health outcomes.

International Registered Report Identifier (IRRID)

DERR1-10.2196/13744