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

Prostate cancer incidence and mortality linked to metalworking fluid exposure: a systematic review and meta-analysis

Background

Prostate cancer is the second most diagnosed cancer in men globally, with high prevalence in North America, Europe, and Australia. Occupational exposures, including metalworking fluids (MWFs), have emerged as a potential risk factor for prostate cancer, yet comprehensive studies on this association are limited.

Objective

This study aims to systematically review and conduct a meta-analysis to examine the incidence and mortality of prostate cancer linked to MWF exposure.

Methods

A systematic review and meta-analysis were conducted following the PRISMA guidelines. A comprehensive search strategy was developed to identify relevant studies from PubMed, Scopus, Embase, and Web of Science. Inclusion criteria encompassed studies reporting on the association between MWF exposure and prostate cancer incidence or mortality. Data extraction and risk of bias assessment were performed independently by two reviewers, with discrepancies resolved by a third reviewer. Statistical analyses were conducted using STATA version 17.

Results

The search identified 1376 unique references, with 5 studies meeting the inclusion criteria for the meta-analysis. These studies, conducted in the USA, primarily involved auto workers and reported Standardized Mortality Ratio (SMR), Relative Risk (RR) and 95% Confidence Interval (95%CI) measures. Meta-analysis revealed an overall RR of 1.06 (95% CI: 1.01-1.11) for prostate cancer incidence and an overall SMR of 1.20 (95% CI: 1.09-1.31) for prostate cancer mortality, indicating a statistically significant increased risk and mortality among MWF-exposed workers.

Conclusions

These findings carry significant implications for workplace safety regulations. Given the observed association between MWF exposure and prostate cancer risk, it is imperative to minimize occupational exposure through the implementation of effective engineering controls, personal protective equipment, and substitution of less hazardous fluids. Regular health surveillance and education programs for workers in industries utilizing MWFs are also essential to mitigate risk. Additionally, regulatory agencies should consider revising exposure limits and safety guidelines to account for emerging evidence on the carcinogenic potential of newer MWF formulations.

Health Outcomes Related to Multiple Exposures in Occupational Settings: A Review

Individuals are constantly exposed to hazardous factors that can affect their health, the hazards encountered in the workplace can lead to the development of occupational diseases. Risk mitigation measures help to reduce the risks, but they are often designed without consideration of interactions between occupational exposures. Therefore, there is a need for research and it resulted in international research plans and programmes. The aim of this scoping review is to provide an overview of the scientific results related to the link between multiple occupational exposures and human health outcomes. Sixty-three articles were reviewed. Research articles were included only if they mentioned: several combined exposures, the direct characterisation of each exposure, and exposure/health outcome associations. Seven activity sectors were identified: 'extraction and energy production and distribution', 'health care', 'banks, public administration and defence', 'chemical production', 'manufacturing industry', 'agriculture and food industry' and 'transport and logistics'. Six multiple exposures scenarios were identified: chemical (n = 35), chemical/physical-biomechanical (n = 22), chemical/psychosocial-organisational (n = 6), physical-biomechanical (n = 9), physical-biomechanical/psychosocial-organisational (n = 13), and psychosocial-organisational (n = 12). The health problems identified concern nervous, mental, respiratory, musculoskeletal, auditory and other systems. Eighty-eight of 97 (91%) multiple exposure/health problem associations were reported to be statistically significant. Twenty studies (32%) provided specific risk prevention advice for multiple exposures. Prevention aimed at reducing risks to workers' health is still underdeveloped, further research is needed to improve prevention methods. No study was related to biological risk, and some other multiple exposures known to have health effects were not identified as well. This highlights the need for more multiple exposures research.

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.

Revisiting the g-null Paradox

The (noniterative conditional expectation) parametric g-formula is an approach to estimating causal effects of sustained treatment strategies from observational data. An often-cited limitation of the parametric g-formula is the g-null paradox: a phenomenon in which model misspecification in the parametric g-formula is guaranteed in some settings consistent with the conditions that motivate its use (i.e., when identifiability conditions hold and measured time-varying confounders are affected by past treatment). Many users of the parametric g-formula acknowledge the g-null paradox as a limitation when reporting results but still require clarity on its meaning and implications. Here, we revisit the g-null paradox to clarify its role in causal inference studies. In doing so, we present analytic examples and a simulation-based illustration of the bias of parametric g-formula estimates under the conditions associated with this paradox. Our results highlight the importance of avoiding overly parsimonious models for the components of the g-formula when using this method.

Liposome encapsulated electron donor strategy for signal-on CYFRA 21-1 photoelectrochemical analysis

A novel electron donor controlled-release system is proposed based on liposome encapsulated L-cysteine for the sensitive determination of cytokeratin 19 fragment 21-1 (CYFRA 21-1). On the one hand, a defective TiO₂ modified with methylene blue was employed as a photoactive platform which exhibited a high photoelectrochemical (PEC) response owing to the introduction of oxygen vacancies and the high  photosensitivity of the dye. On the other hand, L-cysteine as the sacrificial electron donor was encapsulated in the vesicles of liposomes, and this composite was used as the signal amplification factor, which is labeled on the secondary antibody of CYFRA 21-1 to further improve the photocurrent sensitivity. The excellent electron transfer path in photoactive materials coupled with the skilful electron donor controlled-release system, contributed to the sensitive  PEC analysis of CYFRA 21-1 underoptimum conditions. The PEC immunoassay showed a linear current response in the range 0.0001-100 ng/mL with a detection limitof 37 fg/mL. Enhanced stability and satisfactory reproducibility were also achieved. The proposed concept  provides a novel signal-on strategy for the sensitive detection of other cancer markers in the electrochemical sensing field.

Metalworking fluids and cancer mortality in a US autoworker cohort (1941-2015)

Objectives This report describes the extended follow-up (1941-2015) of a cohort of 38 549 automobile manufacturing workers with potential exposure to metalworking fluids (MWF). The outcomes of interest were mortality from cancers of the esophagus, stomach, intestine, rectum, bladder, liver, pancreas, larynx, lung, skin, prostate, brain, and female breast, as well as leukemia. This report includes 5472 deaths from cancer, more than ten times the numbers of deaths in our last summary report published 20 years ago. Methods Standardized mortality ratios were computed for the entire study period. Adjusted hazard ratios (HR) were estimated in Cox proportional hazard models with categorical variables for cumulative exposure to each type of MWF. Results Exposure-response patterns are consistent with prior mortality reports from this cohort. We found increased risk of skin and female breast cancer with straight fluids. For the first time, we found elevated risk of stomach cancer mortality. Overall, many of the exposure-response results did not suggest an association with MWF. Conclusions Mortality is a poor proxy for cancer diagnosis for treatable cancers and not the optimal outcome measure in etiological studies. Although the HR presented here handle bias from the healthy worker hire effect and left truncation, they do not handle bias from healthy worker survivor effect, which likely results in underestimates of the health impacts of MWF. Although this updated summary provides some information on the risk of cancer from MWF, targeted future analyses will help clarify associations.