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Abstract: Objectives: Nanoparticles (NPs), including hazardous substances, are generated in crematoriums due to the high temperatures during the combustion process. NPs are reported to greatly impact animals' health by reaching the alveoli and being carried to the entire body through the blood stream. However, studies in crematoriums have yet to assess workers' exposure to the generated NPs. The purpose of this study is to assess workers' exposure to NPs released in crematoriums. Methods: Field surveys were conducted in three crematoriums with an emphasis on cremation, bone rearrangement and cleaning processes. The NP concentrations and size distributions were analyzed. The deposition of NPs in each respiratory region during each working process was calculated based on the measured data using the Human Respiratory Tract Model. Results: The mean particle number concentration was maximized momentarily during the bone rearrangement process. The concentration at the time a crematory's door was opened was 500,000 particle/cm3. NPs aggregated to micro-sized particles within a few minutes, dust generated by the bone rearrangement, or both. As a result of model calculation, the mean ratios (alveolar per the other regions by a crematory) were approximately 3.0 (bronchus and bronchioles regions: except for the first survey in crematorium A which had the obstruction of measurement) and 4.3 (extrathoracic airways). The ratios were similar for all crematoriums. Conclusions: These results can be used for health risk assessments in crematoriums. In addition, these results should be applicable to estimate the inhalation unit risk of each respiratory organ such as lungs and nose.
(J Occup Health 2017; 59: 572-580)
doi: 10.1539/joh.17-0008-FS
Key words: Crematorium, Exposure assessment, Human Respiratory Tract Model, Nanoparticle, Risk assessment
Introduction
The number of crematoriums has increased globally in the past few decades1,2). In particular, the death population of Japan is increasing every year and reached 1.3 million deaths per year as of 2015 (total death population, including still-born infants). Atmospheric pollution from crematoriums is becoming more serious: the cremation ratio in Japan is approximately 99.9%3). The studied pollutants are mainly polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs)4-6), heavy metals (especially mercury released from amalgam fillings in teeth7-11)), combustion gases (NOx, SOx, CO, HCl), and particulate matter (PM)12-15). Soot dust produced during cremation includes the abovementioned substances.
The concentration range of PCDD/Fs depends greatly...