Researchers are in the process of analyzing data collected in the past years. They are combining data from the occupational exposure study with data from the health studies to more clearly understand the lung health of workers in the taconite industry. The researchers remain committed to conducting rigorous, scientific research through a process that is open and engaging of the stakeholders.
An analysis of the occupational exposure measurements leads to the following preliminary conclusions: (a) The amphibole elongated mineral particles (EMP) concentration was much less than the total EMP concentration, a result indicating that amphibole EMP are not major components of taconite EMP; (b) The respirable dust measurements are nearly all below the regulatory limit; (c) Silica measurements were frequently over the regulatory limit. This is similar to Mine Safety and Health Administration (MSHA) findings. Further analysis of the silica exposures is expected to be completed later this year.
Preliminary analysis of the mortality (cause of death) data for workers based on number of years they worked in the industry confirms, as expected, elevated standardized mortality ratios (SMRs) from mesothelioma and lung cancer. Several other causes of death were evaluated, and these were not elevated but determined to be as expected (i.e. no higher risk for taconite workers). Cause of death from several common diseases of other major organs/systems (cancer of esophagus, stomach, breast; diabetes, COPD, kidney disease and neurological diseases such as Parkinson’s, etc.) were also found to be similar for those living in Minnesota and not working in the taconite industry. However, heart disease (hypertension and ischemic) was higher than is normally seen in a working population. This is an area that warrants further investigation but is not within the scope of this research project.
Incidence studies for mesothelioma, lung cancer, and nonmalignant respiratory diseases (NMRD) are progressing. The work records for all cases and controls are being collected in detail, including all job titles with the worker’s respective start and stop dates. The next major effort in this area will be combining work history data with the exposure information. This will help define the role of the workplace in each of the diseases of interest, (mesothelioma, lung cancer, and non-malignant respiratory diseases).
The research team is continuing to conduct analysis of the lung function tests and the chest X-rays collected during the Respiratory Health Survey of Taconite Workers and Spouses research clinics. The data for spouses has yet to be analyzed but preliminary spirometry results indicate that approximately 17% of workers tested have lower amounts of forced exhaled air volume than expected (an abnormality commonly seen in people with asthma or emphysema) and that 4-6% of workers had lower than expected amounts of inhaled and exhaled air volume (an abnormality more commonly seen from dust exposure). The X-ray results indicate 15-17% of the workers have abnormalities in the tissue surrounding the lung (pleural) and the 4-6% of the workers have abnormalities in the tissue of the lung (parenchymal). Combining the breathing tests results with the chest X-rays interpretations while incorporating the exposure information will enhance the accuracy of determining the presence of dust-related lung disease.
The study of airborne particulates being conducted by NRRI is in the final stages of analytical work. All community and in-plant sampling has been completed. Laboratory analyses need to be integrated, and physical, chemical, mineralogical and spatial evaluations must be completed before the results can be released. The study team is developing aids in which to help with the interpretation and reporting of the results which are expected later this year, after rigorous review by the Science Advisory Board.