Human Risk from Exposure to Heavy Metals and Arsenic in Water from Rivers with Mining Influence in the Central Andes of Peru
, Walter Cuadrado 2, Richard Peñaloza 1, Raúl Montalvo 1, Salomé Ochoa 1 and Jocelyn Quispe 1Round 1
Reviewer 1 Report
The manuscript needs a revision focusing on a critical review of the results and discussion in the context of the aims of the study. English editing is recommended.
Abstract and introduction: Please note that this study is timely, important and innovative. In this work the state of the art is not given at all and, hence, it is not clear if and how this study is timely, important and novel. On the other hand, too many details are given as findings and thus the highlights of the research are not clearly underlined.
The limitations of the study are not stated, recommendations for future work not provided and there is no wider context or relevance of the work given.
Conclusions: Please clarify the conclusions. In their present form conclusions are rather a summary.
Author Response
Response to Reviewer 1 Comments
Point 1: Abstract and introduction: Please note that this study is timely, important and innovative. In this work the state of the art is not given at all and, hence, it is not clear if and how this study is timely, important and novel. On the other hand, too many details are given as findings and thus the highlights of the research are not clearly underlined.
Response 1:
Abstract
Water pollution by heavy metals is one of the main concerns of today's society due to the strong anthropogenic pressure on the aquatic environment; this constitutes a great risk to the human rights of access to drinking water. In this context, the risk to humans from exposure to heavy metals and arsenic in water from rivers with mining influence in the central Andes of Peru was assessed. Water samples were collected from seven rivers at 63 sampling sites and concentrations of Cu, Fe, Pb, Zn and As were determined by the method of flame atomic absorption spectrophotometry. The cluster analysis grouped the 21 sampling sectors into four groups with similar chemical characteristics. The PCA showed a total percentage change of 86 %. The percentage contribution distribution revealed that Fe, Zn and As had higher contribution percentages. The hazard quotient for ingestion was the most significant for the dermal hazard quotient, in children and adults. The hazard index for ingestion was higher than the threshold value (HIing>1). The HIing of 43% of the rivers evaluated indicated that the adult population is at risk of non-carcinogenic effects and the HIing of 14% of the rivers revealed a very high health risk. The risk of cancer by ingestion for children varied from medium to high risk and for adults from low to high risk.
Introduction
Rapid population growth, increasing urbanization and rapid industrial development have accelerated water pollution. Many researches on water quality, health risks and human rights point out that different development activities; mainly mining, constitute a great risk for human rights to access clean drinking water. Fan et al. [11] analyzed river water quality in the Pearl River Delta in China using multivariate statistical techniques showing that water quality is increasingly deteriorating due to anthropogenic pollution and accelerated economic development. Abdel-Satar et al. [12] evaluated the water quality of the Nile River in Egypt using environmental indices (HPI and Cd) revealing that Nile waters are significantly contaminated with heavy metals. Othman et al. [13] investigated the distribution, source and environmental risk of heavy metals in the Selangor river basin in Malaysia finding elevated concentrations of As, Fe and Mn that exceeded standard values and possible sources of heavy metals to industries located in this basin. Saha et al. [14] evaluated heavy metal contamination of the Bangshi River in Bangladesh showing heavy metal concentrations above drinking water quality guidelines and an average non-carcinogenic risk (HI > 1).
In Latin America, Flores et al. [15] analyzed the concentrations of heavy metals in water and surface sediment of the Ilusiones Lagoon in Mexico finding that the heavy metals in water do not exceed the standard values of the Mexican regulations. In contrast, the heavy metals determined in sediment exceed the limit values of the Canadian and U.S. standards, posing a risk to biota. Salazar-Lugo et al. [16] studied heavy metals in the Orinoco River aquatic environment showing concentrations within limits for unpolluted water and sediment; however, in fish the concentrations of Cd and Pb were high. Barra-Rocha et al. [17] monitored the concentration of heavy metals in the waters of the main tributaries of the São Mateus stream basin in Brazil showing pollution rates that are of concern due to high contents of Hg, Cu, Pb and Zn that violate environmental regulations. In Peru, mining has been one of the main economic activities for more than a century with negative effects on the quality of water bodies. Gammons et al. [18] monitored the levels of mercury and other heavy metals in the headwaters of the Ramis River finding very high concentrations of Hg and other heavy metals in the headwaters streams near the mining centers. Monroy et al. [19] determined the concentrations of heavy metals in Lake Titicaca showing high concentrations of Pb and most of the metals in the water at the discharge points of the main tributary rivers exceeding the safety thresholds established by international legislation. Guittard et al. [20] characterized the variability of trace metals in the Santa River Basin from large-scale synoptic sampling revealing higher Mn concentrations than international standards that could affect human and ecosystem health.
Point 2: The limitations of the study are not stated, recommendations for future work not provided and there is no wider context or relevance of the work given.
Response 2:
The study is limited spatially to the Mantaro River basin in central Peru and temporally to the autumn season (dry season).
Further studies of the dynamics of other heavy metals in the Mantaro River and tributary rivers are recommended. As well as, in suspended sediment during seasonal periods of high flow.
Point 3: Conclusions: Please clarify the conclusions. In their present form conclusions are rather a summary.
Response 3:
The rivers of the Mantaro river watershed in central Peru are exposed to contamination by heavy metals and metalloids from natural and anthropogenic sources; among the latter, the mining-metallurgical industry, agricultural activity and manufacturing industry, mainly. The magnitude of contamination by heavy metals and arsenic in the rivers evaluated requires more frequent monitoring and supervision of the mining-metallurgical industries (which discharge their liquid waste into water bodies) by the competent entities. As well as agricultural and other anthropogenic activities with an impact on water quality. Of the rivers evaluated, the Mantaro river has the highest concentrations of heavy metals and arsenic, which exceed the environmental water quality standards of Peru, the WHO and USEPA.
The assessment of carcinogenic and non-carcinogenic risks due to exposure to heavy metals and arsenic through the routes of ingestion and dermal contact showed that in both children and adults the route of ingestion contributed most to the non-carcinogenic and carcinogenic risk. These findings demonstrate the urgent need for effective policies to control and reduce the pollution levels of the rivers evaluated, whose waters are destined for a variety of uses. Therefore, further studies of the dynamics of other heavy metals in the Mantaro River and tributary rivers are recommended. As well as, in suspended sediment during seasonal periods of high flow.
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Author Response File: 
Author Response.docx
Reviewer 2 Report
The study by Custodio and Co-authors present their results on heavy metals analysis from river water samples from Montaro river basin. Mainly, heavy metals such as Cu, Fe, Pb, Zn and As were determined using atomic absorption spectrophotometry. Usage of multivariate analysis was added to the support the data. The study is very interesting towards environmental risk assessment and human health risk assessment. Overall, the manuscript is very well crafted and the results are useful for risk assessment.
Other comments:
Abstract: It would be better to include the range of concentrations obtained in this study in the abstract.
Introduction: References [15-20] – range of concentrations can be presented.
Line 53: consider modifying health toxicity to ‘health effects’
Conclusions: the highest concentration of heavy metal concentrations obtained can be listed here.
Author Response
Response to Reviewer 2 Comments
Point 1: Abstract: It would be better to include the range of concentrations obtained in this study in the abstract.
Response 1:
Abstract
Water pollution by heavy metals is one of the main concerns of today's society due to the strong anthropogenic pressure on the aquatic environment; this constitutes a great risk to the human rights of access to drinking water. In this context, the risk to humans from exposure to heavy metals and arsenic in water from rivers with mining influence in the central Andes of Peru was assessed. Water samples were collected from seven rivers at 63 sampling sites and concentrations of Cu, Fe, Pb, Zn and As were determined by the method of flame atomic absorption spectrophotometry. The cluster analysis grouped the 21 sampling sectors into four groups with similar chemical characteristics. The PCA showed a total percentage change of 86 %. The percentage contribution distribution revealed that Fe, Zn and As had higher contribution percentages. The hazard quotient for ingestion was the most significant for the dermal hazard quotient, in children and adults. The hazard index for ingestion was higher than the threshold value (HIing>1). The HIing of 43% of the rivers evaluated indicated that the adult population is at risk of non-carcinogenic effects and the HIing of 14% of the rivers revealed a very high health risk. The risk of cancer by ingestion for children varied from medium to high risk and for adults from low to high risk.
Point 2: Introduction: References [15-20] – range of concentrations can be presented.
Response 2:
In Latin America, Flores et al. [15] analyzed the concentrations of heavy metals in water and surface sediment of the Ilusiones Lagoon in Mexico finding that the heavy metals in water do not exceed the standard values of the Mexican regulations. In contrast, the heavy metals determined in sediment exceed the limit values of the Canadian and U.S. standards, posing a risk to biota. Salazar-Lugo et al. [16] studied heavy metals in the Orinoco River aquatic environment showing concentrations within limits for unpolluted water and sediment; however, in fish the concentrations of Cd and Pb were high. Barra-Rocha et al. [17] monitored the concentration of heavy metals in the waters of the main tributaries of the São Mateus stream basin in Brazil showing pollution rates that are of concern due to high contents of Hg, Cu, Pb and Zn that violate environmental regulations. In Peru, mining has been one of the main economic activities for more than a century with negative effects on the quality of water bodies. Gammons et al. [18] monitored the levels of mercury and other heavy metals in the headwaters of the Ramis River finding very high concentrations of Hg and other heavy metals in the headwaters streams near the mining centers. Monroy et al. [19] determined the concentrations of heavy metals in Lake Titicaca showing high concentrations of Pb and most of the metals in the water at the discharge points of the main tributary rivers exceeding the safety thresholds established by international legislation. Guittard et al. [20] characterized the variability of trace metals in the Santa River Basin from large-scale synoptic sampling revealing higher Mn concentrations than international standards that could affect human and ecosystem health.
Point 3: Line 53: consider modifying health toxicity to ‘health effects’.
Response 3:
Line 53: Heavy metals have the ability to replace some cations in the water, resulting in health effects.
Point 4: Conclusions: the highest concentration of heavy metal concentrations obtained can be listed here.
Response 4:
The rivers of the Mantaro river watershed in central Peru are exposed to contamination by heavy metals and metalloids from natural and anthropogenic sources; among the latter, the mining-metallurgical industry, agricultural activity and manufacturing industry, mainly. The magnitude of contamination by heavy metals and arsenic in the rivers evaluated requires more frequent monitoring and supervision of the mining-metallurgical industries (which discharge their liquid waste into water bodies) by the competent entities. As well as agricultural and other anthropogenic activities with an impact on water quality. Of the rivers evaluated, the Mantaro river has the highest concentrations of heavy metals and arsenic, which exceed the environmental water quality standards of Peru, the WHO and USEPA.
The assessment of carcinogenic and non-carcinogenic risks due to exposure to heavy metals and arsenic through the routes of ingestion and dermal contact showed that in both children and adults the route of ingestion contributed most to the non-carcinogenic and carcinogenic risk. These findings demonstrate the urgent need for effective policies to control and reduce the pollution levels of the rivers evaluated, whose waters are destined for a variety of uses. Therefore, further studies of the dynamics of other heavy metals in the Mantaro River and tributary rivers are recommended. As well as, in suspended sediment during seasonal periods of high flow.
Author Response File: Author Response.docx
Round 2
Reviewer 1 Report
The manuscript has been greatly improved.
Author Response
Distinguished Reviewer
The article was submitted to the English edition.
Author Response File: 
Author Response.pdf
This manuscript is a resubmission of an earlier submission. The following is a list of the peer review reports and author responses from that submission.
Round 1
Reviewer 1 Report
The manuscript presents the content of some metals (Cu, Zn, Fe, Pb) and metalloids (As) in river waters from Peru and the non-carcionogenic and carcinogenic health risk associated to ingestion and dermal exposure of humans to contaminated waters. The paper study an important issue in the context of good quality water shortage and raise attention of possible health effects that could appear after the use of surface waters with inappropriate quality. However, the results are of regional interest and a comparison with similar cases in the world (use of surface waters impacted by mining or other anthropogenic activities) could raise the manuscript value. I recommend the manuscript publication after revision. Please find bellow some specific comments:
- Please revise the grammar and typing errors through the whole manuscript. Some examples: L34- bioaccumulate instead of bioaccumulation, L109- 100 ml phial? probably vial, L152 HI<1 instead of H<1, L323-324 please rephrase, L364-368 please rephrase and eliminate duplicate sentence.
- Introduction-please mention the most important results of recent published studies regarding the human health risk through contaminated waters consumption.
- L86-87. Please revise the sentence
- Section 2.2. please add details on quality control and quality assurance. Please add date on limit of detection, limit of quantification, repeatability and reproducibility of the method. How do you are assured that the As was not volatilized from the samples during sample preparation (evaporation through boiling)?
- Section 2.2. Why only Fe, Cu, Pb, Zn, As were determined?
- Table 2 and 3 please differentiate HI for ingestion (Tab 2) from HI for dermal (Tab 3), Similar with HQ (e.g. HIing ?)
- Section 4.1 please compare results with similar recent studies all over the world (e.g. Hoagia et al. Analytical Letters 52(8), 2019).
- Section 4.2. refer/ compare to HQ values in other mining regions ? As water is only a low part of the daily basket, the risk is much higher if we consider also the ingested foods (e.g. Miclean et al., Journal of Environmental Science and Health, Part B, 2018;53(9):595-601)
Author Response
Distinguished Reviewer
Previously, we appreciate your comments and notes. I would like to inform you that your request has been answered.
Thank you very much
_________________
Author Response File: Author Response.pdf
Reviewer 2 Report
The manuscript presented a very straight forward work, however some comments are needed to easier the understanding about the paper importance. Some issues need to be clarified or corrected before publication.
English editing is recommended.
Abstract and introduction: Please note that this study is timely, important and innovative. Introduction would be improved by more comprehensive quotes from the timely literature about the health effects of heavy metal contamination of water.
Material and Methods: why you selected only autumn season? Please, describe this accordingly.
Conclusions: Please clarify the conclusions. In their present form conclusions are rather a summary.
Author Response
Revisor distinguido
Anteriormente, apreciamos sus comentarios y notas. Me gustaría informarle que su solicitud ha sido respondida.
Muchas gracias...
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Author Response File: Author Response.pdf
Round 2
Reviewer 2 Report
The manuscript has been greatly improveed.
