Potential Health Risk of Dust from Stone Mill Industries

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

Abstract:

1. It would be beneficial to add a brief description of methods in the abstract.
2. “The study was found that elevated levels of 16 Total Suspended Particulate (TSP) and Particulate Matter-10 micron (PM10) were found in 17 the ambient air, particularly during winter.” Please improve the language expression.
3. Most information in the abstract is subjective/qualitative since authors used the words like “elevated”, “significant”, “major”, “meteorological”, “higher”, “highest”, “stricter”, “effective”, “stronger”, etc. for example, what is the meaning of significant impact? What kind of parameters were included in the meteorological factors? What kind of strategies are effective ones? Please convey the real/specific findings from your research.

Introduction:

1. Line 41-46, repeated information was mentioned about “respiratory issues”. There are double commas.
2. Line 55-57, what are those guidelines/standards set by WHO?

Methods:

1. What is the meaning/unit of monitoring frequency in table 1? Adding a note will improve readability.
2. What is the rationale and uncertainties by using ambient concentrations to represent the inhalation concentration?
3. Considering that TSP already covers PM10, is it still reasonable to use Equation (3)?
4. It seems that the names and specification of monitoring instruments/devices are missing.
5. What are the results of questionnaires? Please detail each variable for calculating HQ. you could refer to this article (https://doi.org/10.1016/j.scitotenv.2024.170734), which provides all the HQ calculation details in the supporting information.

Results:

 

1. Regarding the air quality section, only providing the maximum data (which exceeded the threshold) is not sufficient to conclude the air quality conditions. Instead of Table 5, I would recommend to use box plot or present more details of the data.

Author Response

Reviewer 1

I’m appreciate to thank you for all valuable comments from the reviewers which guide the missing points of the original manuscript. These help us to improve the quality of this work. The revision was complied, as following.

Comment 1:Abstract: To add methods in the abstract, To improve the language (The study was found that elevated….during winter), To consider the subjective/qualitative information

Response: Done: The abstract was rewritten and added the method, accordingly

Stone mill operations contribute significantly to air pollution and increase health risks not only workers but also nearby communities. This study aimed to assess the health impacts of stone mill industries highlighted on nearby residents. The research was conducted in two areas: a primary region with a high number of stone mills and an area without stone mills. A questionnaire-based survey was employed, and potential health risks were evaluated using the Hazard Quotient (HQ) method. Total Suspended Particulate (TSP) and Particulate Matter-10 micron (PM10) were analyzed as hazard factors based on monitoring data from sevven stone mills collected between 2008 and 2021. The study was found that residents in major stone mill areas reported higher hazard quotients (HQ) than those living farther from the mills, with a statistically significant association (P < 0.01). Seasonal variations also influenced dust distribution, with the highest TSP and PM10 levels recorded during winter, exacerbating health risks for local populations. The needs for improved community settlement planning, consideration of meteorological conditions, regulatory interventions by relevant agencies, and enhancements in environmental monitoring systems to mitigate the adverse health effects of stone mill operations were recommended.

Comment 2: Introduction: L41-46 repeated information about respiratory issues

Response: Rewritten L 42-44 as following

The health impacts from milling can pose health risks for workers in the milling facility, causing respiratory issues if inhaled over prolonged periods, especially in poorly ventilated environments

Comment 3: L 55-57: What are those WHO guideline?

Response: Done: added guideline details L55 as following

Global Ambient Air Quality Guidelines set by the World Health Organization (WHO).

Comment 4: Methods: To add note monitoring frequencies unit in Table 1

Response:

Table 1

Monitoring Frequencies were performed 2 or 1 times per annum for each monitoring station.

Comment 5: The rationale and uncertainties by using ambient concentration to represent the inhalation concentration

Response: 1)Add explanation:

L 149-155

The rationale for utilizing monitoring results for ambient concentration measurements is that these data were continuously collected and encompassed the areas surrounding the stone mills. Additionally, the monitoring stations were established based on impact assessments for each stone mill, thereby reflecting the potential ambient concentration levels to which the local population was exposed. However, factors such as individual lifestyles, property characteristics, and topographical variations may introduce uncertainties in the actual exposure levels experienced by the sampled population.

2) Add duration period of monitoring data used in this study (2008-2021) in the abstract and highlighted in Table 1

Comment 6: To add the name and specific of monitoring instruments/ device

Response: Done

L 140-142

The measurement of TSP and PM10 was conducted using the gravimetric method with a high-volume air sampler. This method complies with the requirements established under Thailand’s Environmental Act (NEQA, 1992).

Comment 7: To provide more details regarding the results of questionnaire used to calculate HQ

Response: Done

1. More explanation

L 183-186

The ET, EF, ED, BW, and AT factors were specific to each individual [21]. These factors were calculated using respondent data obtained from the questionnaire results.

Add and refer to j.scitotenv.2024.170734

Comment 8: TSP cover PM10, is it still reasonable to use EQ3?

Response: Thank you for this valuable suggestion, It was our missing error. The reason was that both TSP and PM 10 were performed for monitoring data. In order to correct this error, we removed Eq3 and change HI to HQ.

Comment 9: Recommend to use box plot instead Table 5

Response: Done

Air quality data were presented by box plot (Figure 4, new figure) Instead previous Table 5

 

 

Author Response File: Author Response.pdf

Reviewer 2 Report

Comments and Suggestions for Authors

The article deals with an important environmental health issue in Thailand, but also in other low and middle-income countries where mining is an important economic sector and environmental control is not very efficient or even non-existent. This can be highlighted to improve the interest of readers on the article.

In line 70. Please better explain the "complexities and gaps in legislation remain a concern".

In Methods it is described that 226 out of 542 households were selected, with 150 participants from Moo 3 and 76 from Moo 6 (adding to 226 participants in the sample). I can infer that there was 1 person from each household that anserwed the questionnaire. There need to be an explanation how the selection of the houses was done and who in each house was chosen to answer the questionnaire.

It is also important to describe the questionnaire used in the research and how it was approved by the Ethics commitee.

Study area: Authors should inform the latitude of the area. In line 118 they describe that Thailand has 3 seasons: winter November to February, summer March to May and rainy June to October. As these are not in line with the regular climate seasons year round, a further explanation is needed for readers who are not familiar with Thailand´s geography. Is this a scientific or a popular classification?

In table 1 line 124. Monitoring frequencies. The number refers to frequency/year or in total.

References are up to date and relevant. Similar studies undeertaken in other areas or countries could be mentioned in the discussion.

In the discussion of the results, the study liminations should be presented, in special the use of questionnaires for calculating exposure time, frequency, duration, body weight and time period. Many bias can result from this technique....

HI - Hazard Index was based on USEPA´s guidelines for health risk assessment.  This might also be a limitation of the study as Thai population might be more vulnerable for historical social reasons.

The long term effects of exposure to high PM10 levels might be significant and more important then the results obtained for short term and season of the year.

All those aspects could be discussed in the manuscript and the results compared to other similar studies found in the literature.

Comments on the Quality of English Language

In general the English is clear and easy to understand. However, there are few sentences that need re-writing. Examples:

line 61: Since 2024 there has been 436 stone industries in Thailand.

line 82: many studies have been focused.....(missing on)

line 243: settlement paaterns were tremendous factor that have an effected by stone mills operation

line 276: together with controlled by competent agencies

 

Author Response

Reviewer 2

I’m appreciate to thank you for all valuable comments from the reviewers which guide the missing points of the original manuscript. These help us to improve the quality of this work. The revision was complied, as following.

Comment 1: For more interesting, to highlight an important environmental health issue

Response: Add

L59-60

As a middle-income country where mining constitutes a significant economic sector, environmental control measures remain insufficient.

Comment 2: To explain “complexities and gaps in legislation remain concern”

Response: more explanation

L71-74 (Introduction)

Legislative enforcement for stone mills in Thailand is not managed by a single regulatory agency. Instead, multiple agencies are involved in overseeing the environmental control of project operations. The complexities and gaps in the enforcement of regulations among these agencies remain a significant concern.

L309-315 (discussion)

The legislation governing stone mill industry activities in Thailand is only marginally interconnected, often leading to regulatory conflicts among controlling agencies. Specifically, for stone mill industries—the focus of this research—DPIM holds full authority under the Mineral Act B.E. 2560 (2017). However, the Pollution Control Department (PCD) typically intervenes only when significant environmental damage to natural resources has already occurred. Moreover, the EISs included in project evaluations have proven ineffective in preventing environmental degradation.

Comment 3: To explain the method to calculate  sampling population and the representative of respondent in each house

Response: More explanation

Previous: Representative households were selected using [16], with 150 from 360 households in Moo 3 and 76 from 182 households in Moo 6, totaling 226 out of 542 households.

Change to (L105-113)

         The population frame consists of households located in the vicinity of stone grinding mills in Na Phra Lan Subdistrict, Chaloem Phra Kiat District, Saraburi Province. It includes Village Moo 3, which has the highest number of stone grinding mills, and Village Moo 6, which has the lowest number. The total population consists of 542 households. The sample size was determined using [16] formula, with a sampling error of 0.05 and a confidence level of 95%, resulting in a sample size of 226 households. The sample was then proportionally allocated based on the number of households in each village, resulting in 150 households from Moo 3 and 76 households from Moo 6. The samples were selected using simple random sampling from the population frame.

Comment 4: To describe questionnaire used and how it was approved by the Ethic committee

Response: Add section 2.2 Questionnaire L119-130

The questionnaire consisted of two main sections. The first section gathered baseline information about the interviewees, including gender, age, occupation, weight, duration of residence in the area, underlying health conditions, and behaviors related to health. The second section focused on environmental factors associated with the respondents' properties, such as house location, distance from roads and stone mills, road characteristics, potential impacts from stone mill operations, and other nearby activities contributing to TSP.

Each household was represented by a single sample, with only the household head or primary income earner selected as the respondent. The questionnaire and study protocol were reviewed and approved by the Ethics Committee of Silpakorn University in accordance with the Declaration of Helsinki.

Comment 5: To inform the latitude of the areas

Response: Add in L.93 the manuscript

14° 36´ 9.0" N 100° 54´ 5.0" E

Comment 6: To provide more information regarding  Thailand season

Response: Rewritten from :Thailand has three seasons: winter (November–February), summer (March–May), and rainy (June–October).

To L145-147

Thailand has three seasons: winter (November–February), summer (March–May), and rainy (June–October). Thailand is situated in the tropical zone and experiences three distinct seasons: winter (November–February), summer (March–May), and rainy (June–October), as classified by [17] based on earth tilted and axis.

Comment 7: To add monitoring frequency

Response: Add more explanation in Table 1

Monitoring frequencies (per year)**

**Monitoring Frequencies were performed 2 or 1 times per annum for each monitoring station.

Comment 8: To provide the limitation of study

Response: Add limitation of study in L345-362

This study acknowledges several limitations. First, unintentional bias may have been encountered during data collection, as interviewees’ responses could have been influenced by their attitudes or past experiences. To mitigate such biases, the questionnaire was designed to emphasize objective questions while avoiding subjective or opinion-based inquiries.

Second, the Hazard Quotient (HQ) was used to assess risk following USEPA guidelines. However, as these indices were originally developed for different population conditions, their applicability to the Thai population may be limited. To address this concern, ET, EF, ED, BW, and AT factors in this study were derived from actual data collected from the sampled population.

Lastly, the study's health risk assessment focused on TSP and PM10 levels from stone mill monitoring data. However, population health is influenced by multiple factors beyond these specific pollutants. Other pollutants from additional sources that may contribute to cumulative health effects were beyond the study's scope.

Despite these limitations, the findings provide valuable insights into previously overlooked factors contributing to health risks. These insights can serve as a basis for improving regulatory measures and developing guidelines for more sustainable stone mill operations.

Comment 9: suggest rewriting these sentences

Since 2024, there have been 436 stone mill industries operated in Thailand, 60 of which are located in Saraburi province, the central part of the country [9].

Response: Done

L61-63

As of 2024, a total of 436 stone mill industries have been operating in Thailand, with 60 located in Saraburi Province, situated in the central region of the country [9].

Comment 10: suggest rewriting these sentences

Many studies have been focused health impacts from stone mills to stone mill workers [13,14] due to prolonged exposure to stone dust, including a high prevalence of chronic obstructive pulmonary diseases [15], 

Response: Done

L85-87

Numerous studies have focused on the health impacts of stone mills on workers [13,14], primarily due to prolonged exposure to stone dust, which has been associated with a high prevalence of chronic obstructive pulmonary diseases [15].

Comment 11: suggest rewriting these sentences

Firstly, community settlement patterns were tremendous factor that have an effected by stone mills operation.

Response: Done

L282

Firstly, community settlement patterns were a significant factor influenced by stone mill operations.

 Remark: Lines specified were based on the complete version.

 

 

Author Response File: Author Response.pdf

Round 2

Reviewer 1 Report

Comments and Suggestions for Authors

thanks authors for revising the article. the paper has been improved significantly. i have no further questions.

Reviewer 2 Report

Comments and Suggestions for Authors

The authors have addressed all the suggestions made in the reviewing process.