A Practical Approach for Uncertainty Management in Rubber Manufacturing Processes Using Physics-Informed Real-Time Models

Industrial manufacturing management can benefit from the use of modeling. For a correct representation of the manufacturing process and the subsequent management, the models must incorporate the effect of the uncertainty propagation throughout the stages considered. In this paper, the proposed methodology for uncertainty management uses a nonintrusive method that is based on building a deterministic physics-informed real-time model for the a posteriori computation of output uncertainties. This model is built using tensor factorization as the Model Order Reduction technique. It includes as model parameters: material properties, process operations, and those random and epistemic uncertainties of known variables. The resulting model is used off-line to identify sensitivities and therefore to unify uncertainty management across the material transformation process. This method is presented by its direct application to an automotive door seal manufactured by continuous co-extrusion of several rubbers and reinforcement (metal strip and glass fiber thread).

Prediction of lung cancer risk using circulating pro-surfactant protein B and high-sensitivity C-reactive protein among Egyptian workers in the rubber industry

OBJECTIVE

For several decades, there has been increasing evidence for excess incidence of lung cancer among workers in the rubber industry. The purpose of this study was to assess the risk of lung cancer occurrence among Egyptian workers involved in the rubber industry using two circulating protein biomarkers.

METHODS

This study was performed in a rubber manufacturing factory in Shubra El-Kheima region in Greater Cairo, Egypt. Environmental assessment for the suspended particulate matter of size 10 µm (PM10) concentrations was done. Levels of plasma pro-surfactant protein B (pro-SFTPB) and serum high-sensitivity C-reactive protein (HsCRP) were measured among the studied population (n = 155) who were divided into two groups. The first group included 75 workers exposed to rubber manufacturing process while the control group involved 80 administrative subjects.

RESULTS

The levels of PM10 neither exceeded the Egyptian nor the international permissible limits where the highest levels were observed in the mixing department. However, through medical history and clinical examination, it was observed that some general and respiratory manifestations were more prevalent among the exposed group when compared with their controls. Laboratory investigations revealed that the mean values of pro-SFTPB and HsCRP levels among exposed workers were significantly higher than those of the control group. These increased circulating proteins levels were strongly and positively correlated with each other and with the duration of employment of exposed workers.

CONCLUSION

The study results support the conclusion that prolonged occupational exposure to rubber manufacturing process is associated with an elevated risk of lung cancer.

Job-exposure matrix for historical exposures to rubber dust, rubber fumes and n-Nitrosamines in the British rubber industry

OBJECTIVES

To develop a quantitative historical job-exposure matrix (JEM) for rubber dust, rubber fumes and n-Nitrosamines in the British rubber industry for 1915-2002 to estimate lifetime cumulative exposure (LCE) for a cohort of workers with 49 years follow-up.

METHODS

Data from the EU-EXASRUB database-rubber dust (n=4157), rubber fumes (n=3803) and n-Nitrosamines (n=10 115) collected between 1977 and 2002-were modelled using linear mixed-effects models. Sample year, stationary/personal measurement, industry sector and measurement source were included as fixed explanatory variables and factory as random intercept. Model estimates and extrapolations were used to construct a JEM covering all departments in both sectors of the rubber manufacturing industries for the years 1915-2002. JEM-estimates were linked to all cohort members to calculate LCE. Sensitivity analyses related to assumptions about extrapolation of time trends were also conducted.

RESULTS

Changes in rubber dust exposures ranged from -6.3 %/year (crude materials/mixing) to -1.0 %/year (curing) and -6.5 %/year (crude materials/mixing) to +0.5 %/year (finishing, assembly and miscellaneous) for rubber fumes. Declines in n-Nitrosamines ranged from -17.9 %/year (curing) to -1.3 %/year (crude materials and mixing). Mean LCEs were 61 mg/m3-years (rubber dust), 15.6 mg/ m3-years (rubber fumes), 2483.2 µg/m3-years (n-Nitrosamines sum score), 18.6 µg/m3-years (N-nitrosodimethylamine) and 15.0 µg/m3-years (N-itrosomorpholine).

CONCLUSIONS

All exposures declined over time. Greatest declines in rubber dust and fumes were found in crude materials and mixing and for n-Nitrosamines in curing/vulcanising and preprocessing. This JEM and estimated LCEs will allow for evaluation of exposure-specific excess cancer risks in the British rubber industry.