---
title: "Probabilistic assessment of respirable dust and lifetime cancer risk in Thai stone carvers"
id: "plos-one-20-probabilistic-health-risk-assessment-of-respirable-dust-exposure-among-stone"
canonical_url: "https://medichelpline.com/clinical-feed/plos-one-20-probabilistic-health-risk-assessment-of-respirable-dust-exposure-among-stone"
content_type: "clinical_feed_article"
specialty: "General"
source_name: "PLOS ONE (Medicine)"
source_url: "https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0359706"
published_at: "2026-10-05T14:00:00.000Z"
evidence_level: "Journal Feed"
license: "CC-BY-NC-4.0 / Informational Use"
---
# Probabilistic assessment of respirable dust and lifetime cancer risk in Thai stone carvers
## Provenance & Clinical Metadata
- **Canonical URL:** https://medichelpline.com/clinical-feed/plos-one-20-probabilistic-health-risk-assessment-of-respirable-dust-exposure-among-stone
- **Specialty:** [General](https://medichelpline.com/clinical-feed/general.md)
- **Primary Source:** PLOS ONE (Medicine)
- **Source URL:** [Original Journal Publication](https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0359706)
- **Published At:** 2026-10-05T14:00:00.000Z
- **Evidence Rating:** Journal Feed
## Executive GIST (TL;DR)
- This cross-sectional study assessed **respirable dust (RD)** exposure and probabilistic cancer risk among informal stone workers in Sikhio District, Nakhon Ratchasima, Thailand, across five task categories: mining, cutting, splitting, knocking, and stone carving. - A total of 243 workers were enrolled for questionnaires and exposure-related information; 83 personal air samples were collected using the NIOSH 7601 method and SKC personal sampling equipment to measure time-weighted average (TWA) RD concentrations. - Monte Carlo simulation with 10,000 iterations was used to estimate the **Incremental Lifetime Cancer Risk (ILCR)** based on average daily dose (ADD)/lifetime average daily dose (LADD) and U.S. EPA guidance; the analysis focused on carcinogenic outcomes and did not quantify non-cancer respiratory risks. - Mean RD concentrations did not exceed the Thai occupational exposure limit (8-h TWA 5 mg/m3) or common TLVs in any occupational category; the highest mean RD was in stone carvers at 0.051 mg/m3. - All occupational groups produced ILCR estimates below the commonly used acceptable threshold of 1.00 × 10−6; the highest mean ILCR was in stone carvers (3.325 × 10−7). - Results indicate that, although measured RD levels and ILCRs were within regulatory thresholds, potential health risks remain, particularly in the stone carving group with the highest exposures and cancer risk estimates. - The authors highlight the need for enhanced regulatory enforcement and comprehensive exposure controls: engineering controls, respiratory protection, and targeted worker health education and surveillance. - Study strengths include use of probabilistic risk modeling (Monte Carlo) to address input variability and uncertainty; limitations noted include dependence on input data quality and that non-cancer outcomes (e.g., silicosis) were not quantified using RfD/RfC due to lack of established values from the EPA. - Funding was provided by the Thai Health Promotion Foundation; data access is managed through the Human Research Ethics Committee of Thammasat University (contact details provided in the source).
## Clinical Analysis & Structured Key Points
Probabilistic health risk assessment of respirable dust exposure among stone carvers in Thailand using average daily dose and Monte Carlo simulation | PLOS One Browse Subject Areas ? Click through the PLOS taxonomy to find articles in your field. For more information about PLOS Subject Areas, click here . Article Authors Metrics Comments Media Coverage Reader Comments Figures Figures Abstract Respirable dust (RD) exposure represents a significant occupational health concern in stone processing settings, particularly among stone carvers who are at elevated risk due to high levels of dust generation. Prolonged exposure to RD is associated with serious adverse health outcomes, including lung cancer. This study aimed to evaluate the probabilistic risk associated with RD exposure using Monte Carlo simulation and to estimate the Incremental Lifetime Cancer Risk (ILCR) among stone carvers. A cross-sectional study was conducted across five occupational categories: mining, cutting, splitting, knocking, and stone carving. Personal air sampling was performed in accordance with the NIOSH 7601 method to determine time-weighted average (TWA) RD concentrations. ILCR was estimated using Monte Carlo simulation with 10,000 iterations, incorporating exposure parameters and health risk assessment models based on U.S. EPA guidelines. The mean RD concentrations did not exceed either the Thai occupational exposure limit (OEL) or the threshold limit value (TLV) in any of the five occupational categories, with the highest level observed among stone carvers (0.051 mg/m 3 ). Although ILCR values for all groups were within the acceptable threshold of 1.00 × 10 −6 , the highest mean ILCR was identified in the stone carving group (3.325 × 10 −7 ). These findings suggest that, despite being within acceptable limits, workers may still face potential health risks from RD exposure. The results underscore the need for strengthened regulatory enforcement and comprehensive control strategies, including engineering controls, respiratory protection, and targeted health education, to mitigate exposure and prevent silica-related diseases in this high-risk population. Citation: Ketsakorn A, Chaiyadej R (2026) Probabilistic health risk assessment of respirable dust exposure among stone carvers in Thailand using average daily dose and Monte Carlo simulation. PLoS One 21(10): e0359706. https://doi.org/10.1371/journal.pone.0359706 Editor: Benedetto Schiavo, National Autonomous University of Mexico Institute of Geophysics: Universidad Nacional Autonoma de Mexico Instituto de Geofisica, MEXICO Received: May 19, 2026; Accepted: September 17, 2026; Published: October 5, 2026 Copyright: © 2026 Ketsakorn, Chaiyadej. This is an open access article distributed under the terms of the Creative Commons Attribution License , which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. Data Availability: Data requests may be directed to the Human Research Ethics Committee of Thammasat University, No. 3, which serves as the official non-author point of contact. Their contact information is as follows: Human Research Ethics Committee of Thammasat University, No. 3; Email: ecsctu3@tu.ac.th ; Phone: +66 2564 4441-79 ext. 1815; Website: https://research.tu.ac.th/ethics3 This committee will securely maintain the dataset and respond to external data access requests in accordance with institutional and ethical guidelines. In addition, our institution has established long-term archiving policies to ensure persistent storage and accessibility of research data, even in the event of changes in author affiliations or availability. Funding: This research project was supported by the Thai Health Promotion Foundation (ThaiHealth) (Grant No. 000705/64). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript. Competing interests: The authors have declared that no competing interests exist. Introduction Respirable dust (RD) is an important occupational hazard that can adversely affect the human respiratory system. Prolonged inhalation of RD may result in respiratory irritation, pulmonary inflammation, and reduced lung function. The severity of these health effects depends on the dust composition, particle size, airborne concentration, and duration of exposure. Therefore, exposure to RD generated during stone-processing activities represents an important occupational health concern among stone carvers. The body’s defense mechanisms trigger alveolar macrophages to engulf and attempt to remove the deposited particles; however, this process induces fibrotic changes in the lung tissue (pulmonary fibrosis). Consequently, the efficiency of gas exchange in the alveoli is reduced, impairing oxygen transfer into the bloodstream. Affected individuals may experience symptoms such as shortness of breath, fatigue, chronic cough, and difficulty breathing, which can ultimately lead to death [ 1 ]. Although respirable dust (RD) as a general category has not been classified by the International Agency for Research on Cancer (IARC) as a Group 1 carcinogen, prolonged and repeated exposure to RD may still pose significant occupational health risks, including respiratory irritation, pulmonary inflammation, and impaired lung function [ 2 ]. The World Health Organization (WHO) and the International Labour Organization (ILO) have emphasized the importance of preventing and controlling occupational exposure to airborne and respirable dust (RD). Prolonged and repeated inhalation of RD may cause respiratory irritation, pulmonary inflammation, pneumoconiosis, reduced pulmonary function, and other occupational respiratory diseases [ 3 , 4 ]. The health risks associated with RD exposure depend on the physical and chemical characteristics of the dust, its airborne concentration, and the duration and frequency of exposure. In Thailand, occupational exposure to RD remains an important issue for workers in industries involving mining, construction, stone processing, manufacturing, and other dust-generating activities. Therefore, effective occupational health program should include exposure assessment, workplace dust monitoring, engineering and administrative controls, appropriate respiratory protection, worker training, and health surveillance. Medical surveillance may include respiratory symptom assessment, pulmonary function testing, and chest radiography when appropriate to the worker’s exposure history and clinical risk. In addition, the Department of Labour Protection and Welfare has issued regulations specifying occupational exposure limits for respirable dust. The permissible exposure limit for respirable dust, expressed as an 8-hour time-weighted average (TWA), must not exceed 5 mg/m 3 [ 5 ]. These regulatory measures are intended to ensure that employers implement appropriate monitoring and preventive strategies to reduce respirable dust exposure in the workplace. Respirable dust (RD) consists of fine airborne particles that can penetrate deeply into the lungs and reach the alveolar region. When RD contains crystalline silica, prolonged and repeated inhalation may lead to silicosis, a chronic fibrotic lung disease associated with persistent pulmonary inflammation and progressive scarring of lung tissue. The risk of developing silicosis depends on the crystalline silica content of the dust, airborne dust concentration, particle size, duration of exposure, and cumulative exposure. Therefore, occupational exposure to RD containing crystalline silica is an important risk factor for silicosis. The public health significance of this exposure is reflected in the surveillance data reported in Thailand. According to the Health Data Center (HDC), a centralized national health database maintained by the Ministry of Public Health, surveillance data on silicosis have been systematically collected since 2013. Between 2013 and 2022, a total of 1,779 cumulative silicosis cases were reported nationwide [ 6 ]. Nakhon Ratchasima Province recorded the highest cumulative number of cases, with 538 cases, accounting for approximately 30% of all reported cases in the country. Since 2016, Nakhon Ratchasima has consistently ranked among the top three provinces with the highest reported incidence rates of silicosis per 100,000 population. In 2022, the province reported 66 new cases, corresponding to an incidence rate of 3.44 per 100,000 population, approximately 6.7 times higher than the national average. This placed Nakhon Ratchasima second among the provinces in terms of incidence rate, after Saraburi Province, which reported the highest rate at 4.38 per 100,000 population. These findings highlight the importance of assessing and controlling occupational exposure to RD, particularly RD containing crystalline silica, together with appropriate exposure monitoring and health-surveillance program. Sikhio District in Nakhon Ratchasima Province has been identified as a sandstone resource area dating approximately 140–65 million years ago. The sandstone found in this region is highly resistant to weathering, which has supported the development of local wisdom in utilizing available raw materials for stone processing and carving. The sandstone found in this region is highly resistant to weathering, which has supported the development of local knowledge in utilizing available raw materials for stone processing and carving. These materials are commonly crafted into a variety of products, including decorative wall stones, paving stones, and Buddha statues, and over time, stone carving has become a primary occupation and a significant source of income for local communities. In Thailand, such stone processing and carving activities represent an important economic sector, particularly within local and small-scale enterprises. However, occupational health and safety measures in these settings are often inadequate, leading to elevated exposure risks among workers. Despite the establishment of occupational exposure limits (OELs) and threshold limit values (TLVs) to control RD containing crystalline silica exposure, several studies have reported that actual exposure levels frequently exceed these standards, especially in developing and informal sectors [ 7 , 8 ]. Traditional health risk assessments of RD exposure have typically relied on deterministic approaches, which may not adequately capture variability and uncertainty in exposure conditions and individual susceptibility [ 9 ]. In contrast, probabilistic risk assessment methods, such as Monte Carlo simulation, provide a more robust framework by incorporating distributions of input parameters and generating a range of possible risk outcomes. This approach allows for a more comprehensive evaluation of health risks, particularly in complex occupational environments. One of the key advantages of Monte Carlo simulation is its ability to explicitly account for variability and uncertainty in model inputs, thereby producing probabilistic risk estimates that better reflect real-world exposure scenarios. It also enables sensitivity analysis to identify the most influential parameters affecting risk outcomes, which is valuable for targeted risk management. Furthermore, the method supports decision-making by providing confidence intervals and risk distributions rather than single-point estimates [ 10 , 11 ]. However, Monte Carlo simulation also has several limitations. The accuracy of the results depends heavily on the quality and appropriateness of the input data and assumed probability distributions. In cases where empirical data are limited, assumptions may introduce bias or uncertainty into the model outputs. Additionally, the method can be computationally intensive and may require specialized expertise to implement and interpret correctly [ 12 , 13 ]. Despite these limitations, Monte Carlo simulation remains a powerful tool for enhancing the robustness of health risk assessments in occupational settings. Respirable dust (RD) is an important occupational health hazard, particularly when it contains respirable crystalline silica. Exposure to silica-containing RD may cause silicosis, a progressive non-cancerous occupational lung disease. Although the U.S. Environmental Protection Agency (EPA) has not yet established a reference dose (RfD) or reference concentration (RfC) for quantitative assessment of the non-carcinogenic effects of RD containing crystalline silica, the cancer risk can be estimated using the Incremental Lifetime Cancer Risk (ILCR), a widely accepted measure that estimates the probability of developing cancer over a lifetime due to chronic exposure. ILCR values are calculated using either the average daily dose (ADD) or the lifetime average daily dose (LADD) combined with the cancer slope factor from inhalation (CSF), based on the linear, no-threshold assumption that even low levels of exposure may contribute to cancer risk [ 14 ]. Therefore, this study focused solely on carcinogenic outcomes by evaluating ILCR and did not attempt to quantify the risk of lung cancer or other non-cancerous respiratory diseases. Despite the well-established health risks associated with RD exposure, there remains a notable lack of probabilistic health risk assessment studies focusing on stone workers in Thailand. Most existing research has primarily concentrated on exposure assessment, disease prevalence, or health outcome evaluation, without integrating these findings into comprehensive quantitative risk models. For instance, Chaiyadej and Ketsakorn (2024) developed a rapid prediction model for silicosis risk among stone carvers in Nakhon Ratchasima, providing valuable insights into risk screening; however, the model did not incorporate probabilistic approaches to address variability and uncertainty in exposure parameters [ 8 ]. Similarly, Saiphoklang et al. investigated silicosis and pulmonary function among residents exposed to dust in Saraburi [ 15 ], while Silanun et al. reported the prevalence of silicosis among stone carving workers in Sikhio District, Nakhon Ratchasima [ 16 ]. Although these studies provide valuable epidemiological evidence and data on exposure, they do not quantify the potential lifetime cancer risk of RD exposure using standardized probabilistic risk assessment frameworks. Therefore, a critical research gap remains in the application of Monte Carlo simulation combined with ILCR estimation to characterize the uncertainty and variability of lifetime lung cancer risk among stone workers in Thailand. Materials and methods Study area and work processes This study was conducted in Sikhio District, Nakhon Ratchasima Province, Thailand, a region recognized as a significant sandstone resource area. The sandstone deposits in this area were formed during the Mesozoic Era, specifically from the Late Jurassic to Early Cretaceous periods (approximately 140–65 million years ago), providing an abundant and readily accessible source of raw materials for stone processing and architectural carving [ 17 ]. As a result, stone carving has become a primary occupation and an important source of income for local communities. The study area is characterized by small-scale and informal production systems, where stone processing activities are typically performed in household-based settings. Stone processing and carving activities in the study area were classified into five main occupational categories based on task characteristics and exposure potential: mining, cutting, splitting, knocking, and stone carving, as described by Chaiyadej and Ketsakorn (2024) [ 8 ]. Mining involves sandstone extraction through mechanical and manual methods, generating high dust levels from drilling and material handling. Cutting uses electric saws to shape stone, producing substantial fine dust due to abrasion. Splitting breaks stone into smaller pieces using mechanical force, resulting in airborne dust during impact. Knocking involves surface refinement with hand tools, causing intermittent dust exposure. Stone carving, the final finishing process, entails continuous grinding and shaping, leading to prolonged exposure to fine dust and representing the highest risk for RD exposure. Study design and participations This study employed a cross-sectional design to assess occupational exposure to RD and associated health risks among stone informal workers in Sikhio District, Nakhon Ratchasima Province, Thailand. The study focused on informal workers engaged in five main occupational categories, including mining, cutting, splitting, knocking, and stone carving. Eligible participants were individuals aged between 18 and 60 years who had been actively engaged in stone processing or carving activities for at least one year. A total of 243 participants were randomly selected for inclusion in the study. The total number of informal stone carvers in the study area was estimated to be approximately 310 individuals [ 18 ]. The required sample size was calculated using the Krejcie and Morgan (1970) formula [ 19 ] for a finite population with a 95% confidence level, a margin of error of 5%, and an estimated prevalence of 25.4% based on the study of Silanun et al. (2017) [ 20 ]. The calculated sample size was 242.88, which was rounded up to 243 participants. These participants were included in the questionnaire survey and collection of individual exposure-related information. For workplace exposure assessment, 83 personal air samples were collected according to the Similar Exposure Group (SEG) strategy to represent workers with comparable exposure characteristics rather than sampling every participant individually. Participants were selected using a proportionate stratified sampling method based on the distribution of workers across three subdistricts: Nongnamsai (n = 121), Khlong Phai (n = 147), and Khlong Tabaek (n = 42). A total sample size of 243 participants was obtained and proportionally allocated to each area, including Nongnamsai (n = 95), Khlong Phai (n = 115), and Khlong Tabaek (n = 33) [ 19 ]. Within each subdistrict, participants were recruited using purposive sampling to ensure representation of informal workers engaged in stone processing and carving activities. Data collection and instruments Data collection was conducted using a combination of standardized questionnaires and personal air sampling to assess exposure to RD. The questionnaire was developed based on relevant literature and occupational health guidelines and consisted of three main sections: (1) demographic characteristics and work information (gender, age, marital status, education level, financial status, duration of employment in the area, weight, height, BMI, job functions, second job, working hour per day, working day per week, job experience, job before stone carving, workplace characteristics, and separation of residence from workplace), (2) basic health information, health behavior data, and prevention and control of occupational respiratory diseases (basic health information, working hours, duration of exposure), and (3) concentration of RD and exposure assessment. The content validity of the questionnaire was assessed using the Index of Item-Objective Congruence (IOC), and its reliability was tested prior to data collection. The questionnaire was administered through face-to-face interviews to ensure completeness and accuracy of responses. RD concentrations in the workplace were measured using personal air sampling pumps (Universal PCXR8, SKC Inc., USA) equipped with 10-mm nylon cyclones (GS-1 Conductive Plastic Cyclone, SKC Inc., USA) and mixed cellulose ester (MCE) filters with a pore size of 0.8 µm (SKC Inc., USA). The sampling pumps were calibrated and operated at a flow rate of 1.7 L/min. Each sample was collected over a duration of 240 minutes in accordance with the National Institute for Occupational Safety and Health m
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