Porphyrin metabolism in lymphocytes of miners exposed to diesel exhaust at oil shale mine

Human Biomonitoring in the Oil Shale Industry Area in Estonia-Overview of Earlier Programmes and Future Perspectives

Ida-Viru County, in Eastern Estonia, features industrially contaminated sites–where oil shale has been mined and used for electricity generation, and shale oil extraction. Higher prevalence of respiratory and cardiovascular disease has been found in the region due to high quantities of air pollution. Within the framework of “Studies of the health impact of the oil shale sector—SOHOS,” this analysis aimed to map earlier human biomonitoring (HBM) studies and identify the suitable biomarkers for upcoming HBM in Estonia. Altogether, three studies have been conducted among residents: first, among adults in the 1980's; second, among children in the 1990's; and third, among employees, with a focus on workers and miners in the oil shale chemistry industry in the late 1990's and 2000's. In some of those studies, increased levels of biomarkers in blood and urine (heavy metals, 1-OHP) have appeared; nevertheless, in last 20 years, there has been no population-wide HBM in Estonia. According to air pollution monitoring and emission analysis, the pollutants of concern are benzene, PM₁₀, PM_2.5, and PAHs. In general, there is a decreasing trend in air pollutant levels, with the exception of a slight increase in 2018. One of the aims of HBM is to be analyzed if this trend can be identified in HBM, using similar biomarkers as applied earlier. The future perspective HBM could be divided into two Tiers. Tier 1 should focus on exposure biomarkers as heavy metals, PAH, and BTEX metabolites and Tier 2, in later stage, on effect biomarkers as Ox LDL, TBARS, etc.

Cancer Incidence Trends in the Oil Shale Industrial Region in Estonia

Large oil shale resources are found in Eastern Estonia, where the mineral resource is mined, excavated, and used for electricity generation and shale oil extraction. During industrial activities in the last 100 years, pollutants have been emitted in large amounts, some of which are toxic and carcinogenic. The current study aims to analyse time trends in cancer incidence in the oil shale industry-affected areas and compare them with overall cancer incidence rates and trends in Estonia. We analysed Estonian Cancer Registry data on selected cancer sites that have been previously indicated to have relationships with industrial activities like oil shale extraction. We included lung cancer, kidney cancer, urinary bladder cancer, leukaemia, breast cancer, and non-Hodgkin's lymphoma. A statistically significantly higher lung cancer age-standardized incidence rate (ASIR) was found during the study period (1992-2015) only in males in the oil shale areas as compared to males in Estonia overall: 133.6 and 95.5 per 100,000, respectively. However, there appeared to be a statistically significant (p < 0.05) decrease in the lung cancer ASIR in males in the oil shale areas (overall decrease 28.9%), whereas at the same time, there was a significant increase (p < 0.05) in non-oil shale areas (13.3%) and in Estonia overall (1.5%). Other cancer sites did not show higher ASIRs in the oil shale industrial areas compared to other areas in Estonia. Possible explanations could be improved environmental quality, socio-economic factors, and other morbidities.

Residents' Self-Reported Health Effects and Annoyance in Relation to Air Pollution Exposure in an Industrial Area in Eastern-Estonia

Eastern Estonia has large oil shale mines and industrial facilities mainly focused on electricity generation from oil shale and shale oil extraction, which produce high air pollution emissions. The "Study of the health impact of the oil shale sector-SOHOS" was aimed at identifying the impacts on residents' health and annoyance due to the industrial processing. First, a population-wide survey about health effects and annoyance was carried out. Second, the total and oil shale sectors' emitted concentrations of benzene, phenol, and PM2.5 were modelled. Third, the differences between groups were tested and relationships between health effects and environmental pollution studied using multiple regression analysis. Compared to the control groups from non-industrial areas in Tartu or Lääne-Viru, residents of Ida-Viru more frequently (p < 0.05) reported wheezing, chest tightness, shortness of breath, asthma attacks, a long-term cough, hypertension, heart diseases, myocardial infarction, stroke, and diabetes. All health effects except asthma were reported more frequently among non-Estonians. People living in regions with higher levels of PM2.5, had significantly higher odds (p < 0.05) of experiencing chest tightness (OR = 1.13, 95% CI 1.02-1.26), shortness of breath (1.16, 1.03-1.31) or an asthma attack (1.22, 1.04-1.42) during the previous year. People living in regions with higher levels of benzene had higher odds of experiencing myocardial infarction (1.98, 1.11-3.53) and with higher levels of phenol chest tightness (1.44, 1.03-2.00), long-term cough (1.48, 1.06-2.07) and myocardial infarction (2.17, 1.23-3.83). The prevalence of adverse health effects was also higher among those who had been working in the oil shale sector. Next to direct health effects, up to a quarter of the residents of Ida-Viru County were highly annoyed about air pollution. Perceived health risk from air pollution increased the odds of being annoyed. Annoyed people in Ida-Viru had significantly higher odds of experiencing respiratory symptoms during the last 12 months, e.g., wheezing (2.30, 1.31-4.04), chest tightness (2.88, 1.91-4.33 or attack of coughing (1.99, 1.34-2.95).

Early hematological and immunological alterations in gasoline station attendants exposed to benzene

INTRODUCTION

Elucidation of effective biomarkers may provide tools for the early detection of biological alterations caused by benzene exposure and may contribute to the reduction of occupational diseases. This study aimed to assess early alterations on hematological and immunological systems of workers exposed to benzene.

METHODS

Sixty gasoline station attendants (GSA group) and 28 control subjects were evaluated. Environmental and biological monitoring of benzene exposure was performed in blood and urine. The potential effect biomarkers evaluated were δ-aminolevulinate dehydratase (ALA-D) activity, CD80 and CD86 expression in lymphocytes and monocytes, and serum interleukin-8 (IL-8). The influence of confounding factors and toluene co-exposure were considered.

RESULTS

Although exposures were below ACGIH (American Conference of Governmental Industrial Hygienists) limits, reduced ALA-D activity, decreased CD80 and CD86 expression in monocytes and increased IL-8 levels were found in the GSA group compared to the control subjects. Furthermore, according to multiple linear regression analysis, benzene exposure was associated to a decrease in CD80 and CD86 expression in monocytes.

CONCLUSIONS

These findings suggest, for the first time, a potential effect of benzene exposure on ALA-D activity, CD80 and CD86 expression, IL-8 levels, which could be suggested as potential markers for the early detection of benzene-induced alterations.

Commentary: Flawed scientific-evidence standards delay diesel regulations

Of 188 government-monitored air toxics, diesel particulate matter (DPM) causes seven times more cancer than all the other 187 air toxics combined, including benzene, lead, and mercury. Yet, DPM is the only air toxic not regulated more stringently under the Clean Air Act, as a hazardous air pollutant (HAP). One reason is that regulators use flawed standards of scientific evidence. The article argues (1) that DPM meets all six specified evidentiary criteria, any one of which is sufficient for HAP regulation and (2) that regulators' standards of evidence for denying HAP status to DPM (no DPM unit-risk estimate, inadequate dose-response data, alleged weak mechanistic data) err logically and scientifically, set the evidence bar too high, delay regulation, and allow 21,000 avoidable DPM deaths annually in the U.S.

Weight of the evidence or wait for the evidence? Protecting underground miners from diesel particulate matter

A coalition of mine operators has used a variety of tactics to obstruct scientific inquiry and impede public health action designed to protect underground miners from diesel particulate matter. These workers are exposed to the highest level of diesel particulate matter compared with any other occupational group. This case study profiles a decade-long saga of the Methane Awareness Resource Group Diesel Coalition to impede epidemiological studies on diesel exhaust undertaken by the National Institute for Occupational Safety and Health and the National Cancer Institute, and to derail a health standard promulgated by the Mine Safety and Health Administration. The case study highlights the coalition's mastery of legislative, judicial, and executive branch operations and the reaction of policymakers.

Genotoxic damage in mine workers exposed to diesel exhaust, and the effects of glutathione transferase genotypes

This study was performed in an Estonian shale-oil mine with the purpose to develop and apply a number of biomarkers for occupational diesel-exhaust exposure monitoring. Increased breathing-zone exposures to exhaust from operators of diesel-powered trucks in the mine was confirmed in the environmental monitoring part of the study, showing a 7.5-fold higher exposure to particle-associated 1-nitropyrene (1-NP) in 50 underground workers compared with 42 surface workers [P.T.J. Scheepers, D. Coggon, L.E. Knudsen, R. Anzion, H. Autrup, S. Bogovski, R.P. Bos, D. Dahmann, P. Farmer, E.A. Martin, V. Micka, V. Muzyka, H.-G. Neumann, J. Poole, A. Schmidt-Ott, F. Seiler, J. Volf, I. Zwirner-Baier, Biomarkers for occupational diesel exhaust exposure monitoring (BIOMODEM)-a study in underground mining, Toxicol. Lett. 134 (2002) 305-317; P.T.J. Scheepers, V. Micka, V. Muzyka, R. Anzion, D. Dahmann, J. Poole, R.P. Bos, Exposure to dust and particle-associated 1-nitropyrene of drivers of diesel-powered equipment in underground mining, Ann. Occp. Hyg. 47 (2003) 379-388]. Analysis of DNA damage by the Comet assay on frozen blood samples was performed on the total study group and showed significantly higher levels (p=0.003) in underground workers (smokers) driving diesel-powered excavation machines (median 155 on a scale from 0 to 400, among 47 persons), compared with surface workers who smoked (median of 90, among 46 persons). The level of DNA damage in underground smokers was significantly higher (p=0.04) than in non-smokers. Samples from 2 of the 3 sampling weeks had significantly lower DNA damage compared with the third week, probably due to timely processing and freezing. These samples also showed significant differences (p<0.001) between underground workers (median 145, among 41 persons) and surface workers (median 60, among 30 persons). An HPLC method was developed for the analysis of (32)P-postlabelled 1-NP-DNA-adducts, and was applied to a sub-sample of 20 workers. No significant differences between surface and underground workers were found in this sub-sample with respect to the minor, unidentified adducts that had similar chromatographic properties to 1-NP adducts, and smoking did not have any effect on adduct levels. No significant effects of the genotypes of GSTM1, GSTP1 and GSTT1 on DNA-adducts and on DNA damage as measured by the Comet assay were found in the total study group. The study confirms an increased level of DNA damage in workers exposed to exhaust from truck-driving in the mine. However, the results of the environmental and biological monitoring of 1-NP did not correlate, suggesting that inhalation exposure to diesel exhaust is not reflected by an increase in 1-NP-DNA-adduct levels and/or that factors other than occupational exposure to diesel exhaust are primary determinants of these DNA-adduct levels.