Epidemiology of coal miners’ pneumoconiosis and its social determinants: An ecological study from 1949 to 2021 in China

Pneumoconiosis is the most widely distributed occupational disease worldwide. China is currently the largest coal producer and consumer and the country with the most coal miners and cases of coal workers' pneumoconiosis (CWP). Despite more than 70 years of effort, the problem of CWP and silicosis remains serious. There is a lack of analysis of direct data on coal miners’ pneumoconiosis from all over the country. This study aimed to describe the epidemiology of coal miners’ pneumoconiosis and reveal some important clues regarding its social determinants. The annual incidence rate, 20-year prevalence rate, and incidence rate of coal miners’ pneumoconiosis per million tons in China from 1949 to 2021 were calculated by using the data of annual number of coal miners’ pneumoconiosis diagnosed and reported from the coal mining and dressing industry, the number of coal miners, and the raw coal production, and the relationship between the incident cases of coal miners’ pneumoconiosis and the death toll from coal mine safety accidents was analyzed using Pearson correlation analysis, with the aim of exploring the relationship between the incident cases of coal miners’ pneumoconiosis and its social determinants with an ecological study. From 1949 to 2021, there have been more than 462,000 patients with coal miners’ pneumoconiosis in China, showing double U-shaped distributions with an increasing trend, accounting for about 50.5% (462,000/915,000) of all diagnosed pneumoconiosis in China, while the incidencet rate of coal miners’ pneumoconiosis presents a large W shaped distribution with three peaks over a time span of more than 50 years. From 1949 to 1986, there was a strong correlation between the incident cases of coal miners’ pneumoconiosis and raw coal production, the number of coal miners, and the number of deaths from coal mine accidents (r = 0.849, P < 0.001; r = 0.817, P < 0.001; r = 0.697, P < 0.001, respectively), but there was no such correlation found from 1987 to 2006. It was estimated that the annual incidence rate of coal miners’ pneumoconiosis in China from 2016 to 2020 was 3.4‰ (95% CI: 2.6–4.3‰), and the prevalence rate across the recent 20-year observation period was 4.8% (95% CI: 4.6–4.9%), both measured at the peak or around the peak over the 70 years. In particular, 1963, 1986, 2006, and 2009 were the four important turning points in time. There was a sustained high level of incident cases of coal miners’ pneumoconiosis with double U-shaped curve in China, which may be affected by a variety of social determinants and risk factors.