Risk of Lung Cancer among Japanese Coal Miners on Hazard Risk and Interaction between Smoking and Coal Mining

Coal Miners and Lung Cancer: Can Mortality Studies Offer a Perspective on Rat Inhalation Studies of Poorly Soluble Low Toxicity Particles?

Inhalation studies involving laboratory rats exposed to poorly soluble particles (PSLTs), such as carbon black and titanium dioxide, among others, have led to the development of lung cancer in conditions characterized as lung overload. Lung overload has been described as a physiological state in which pulmonary clearance is impaired, particles are not effectively removed from the lungs and chronic inflammation develops, ultimately leading to tumor growth. Since lung tumors have not occurred under similar states of lung overload in other laboratory animal species, such as mice, hamsters and guinea pigs, the relevance of the rat as a model for human risk assessment has presented regulatory challenges. It has been suggested that coal workers' pneumoconiosis may reflect a human example of apparent "lung overload" of poorly soluble particles. In turn, studies of risk of lung cancer in coal miners may offer a valuable perspective for understanding the significance of rat inhalation studies of PSLTs on humans. This report addresses whether coal can be considered a PSLT based on its composition in contrast to carbon black and titanium dioxide. We also review cohort mortality studies and case-control studies of coal workers. We conclude that coal differs substantially from carbon black and titanium dioxide in its structure and composition. Carbon black, a manufactured product, is virtually pure carbon (upwards of 98%); TiO2 is also a manufactured product. Coal contains carcinogens such as crystalline silica, beryllium, cadmium and iron, among others; in addition, coal mining activities tend to occur in the presence of operating machinery in which diesel exhaust particles, a Type I Human carcinogen, may be present in the occupational environment. As a result of its composition and the environment in which coal mining occurs, it is scientifically inappropriate to consider coal a PSLT. Despite coal not being similar to carbon black or TiO2, through the use of a weight of evidence approach-considered the preferred method when evaluating disparate studies to assess risk- studies of coal-mine workers do not indicate a consistent increase in lung cancer risk. Slight elevations in SMR cannot lead to a reliable conclusion about an increased risk due to limitations in exposure assessment and control of inherent biases in case-control studies, most notably confounding and recall bias. In conclusion, the weight of the scientific literature suggests that coal mine dust is not a PSLT, and it does not increase lung cancer risk.

Cancer and mortality in coal mine workers: a systematic review and meta-analysis

Coal mine workers are exposed to a number of workplace hazards which may increase the risk of cancer and mortality. We conducted a systematic review and meta-analysis to investigate cancer and mortality in coal mine workers We searched in Ovid Medline, PubMed, Embase and Web of Science databases using keywords and text words related to coal mines, cancer and mortality and identified 36 full-text articles using predefined inclusion criteria. Each study's quality was assessed using the Newcastle-Ottawa Scale. We performed random-effect meta-analyses including 21 of the identified articles evaluating cancer and/or mortality of coal mine workers. The meta-analysis showed an increased risk of all-cause mortality (SMR 1.14, 95% CI 1.00 to 1.30) and mortality from non-malignant respiratory disease (NMRD) (3.59, 95% CI 3.00 to 4.30) in cohorts with coal workers' pneumoconiosis (CWP). We found a somewhat increased risk of stomach cancer (1.11, 95% CI 0.97 to 1.35) and of mortality from NMRD (1.26, 95% CI 0.99 to 1.61) in the cohorts of coal miners with unknown CWP status. The meta-analysis also showed a decreased risk of prostate cancer and cardiovascular and cerebrovascular mortality among coal miners. This may be a result of the healthy worker effect and possible lower smoking rates, and perhaps also reflect the physically active nature of many jobs in coal mines. The meta-analysis for lung cancer did not show increased risk in coal miners with CWP (1.49, 95% CI 0.70 to 3.18) or for coal miners of unknown CWP status (1.03, 95% CI 0.91 to 1.18). Lower smoking rates in coal mine workers could explain why case-control studies where smoking was controlled for showed higher risks for lung cancer than were seen in cohort studies. Coal mine workers are at increased risk of mortality from NMRD but decreased risk of prostate cancer and cardiovascular and cerebrovascular mortality. Studies of coal mine workers need long-term follow-up to identify increased mortality and cancer incidence.

Mortality in Miners with Coal-Workers' Pneumoconiosis in the Czech Republic in the Period 1992-2013

While working underground, miners are exposed to a number of risk factors that have a negative impact on their health and may be a cause of an increased mortality in miners. The aim of the study was to compare total and specific mortality in black coal miners with acknowledged coal-workers’ pneumoconiosis (CWP) and without CWP, and the mortality of the general male population in the Czech Republic in the period 1992–2013. The sample consisted of 3476 coal miners with CWP and 6687 ex-coal miners without CWP, who were removed after achieving the maximum permissible exposure (MPE). The mortality risk differences were analyzed with the use of the standardized mortality ratio (SMR) and 95% confidence interval. Significantly higher total mortality (SMR = 1.10; 95% CI: 1.02–1.17), and mortality from malignant neoplasm (SMR = 1.16; 95% CI: 1.03–1.30), lung cancers (SMR = 1.70; 95% CI: 1.41–2.04), and non-malignant respiratory diseases (SMR = 2.78; 95% CI: 2.32–3.31) were found in the sample of coal miners with CWP. In this sample, the severity of CWP was assessed, and the SMR increased with the severity of CWP. The total (SMR = 0.86; 95% CI: 0.82–0.91) and specific mortality of miners without CWP were not higher compared with the general population. In the case where the miners were removed from underground work after achieving the MPE (without CWP), their mortality was not higher than that of the general population, but the mortality of miners with CWP was higher compared to the general population. This mortality was affected by malignant and non-malignant respiratory diseases.

Is Helicobacter pylori infection a risk factor for acute coronary syndromes?

OBJECTIVES

To elucidate risk factors for acute coronary syndromes (ACS), the present study examined whether Helicobacter pylori infection is a risk factor for patients with ACS.

METHODS

We studied 33 male patients with acute coronary syndromes (ACS). All patients were incidence cases of ACS that they did not have a past history of IHD and were at the first onset of ACS. A control group was consisted of 66 males. Controls were at random selected from outpatients. All controls had normal resting electrocardiogram and had no history of IHD. H. pylori seropositivity was determined by an IgG-specific enzyme linked immunosorbent assay (ELISA). We serologically confirmed the presence of antibodies specific to the antigen CagA of H. pylori, using CagA ELISA.

RESULTS

Seropositive rate of IgG antibodies in patients with ACS was 87.9%. A rate of in controls was 66.7%. After adjustment for age, a statistically significant association was found in H. pylori seropositivity between ACS and controls (OR, 3.74; 95% CI, 1.15-12.13). This relation was also significant after adjusted for potential confounding factors (OR, 4.09; 95% CI, 1.10-15.17). Anti-CagA positive H. pylori were significantly recognized in ACS (adjusted OR, 3.58; 95% CI, 1.08-11.82). However, this significant association was disappeared after adjusted for potential confounding factors (P=0.054).

CONCLUSIONS

We confirmed a significant link between H. pylori infection and ACS. H. pylori infection is likely to be a risk factor for ACS.