Pa ge 1 Pa ge 1 American Journal of Environment and Climate (AJEC) Ecological and Health Risks of Heavy Metals to the Residents affected by a Volcanic Eruption in the Philippines Genevee M. Banta1*, Cristina C. Salibay1 Volume 4 Issue 2, Year 2025 ISSN: 2832-403X (Online) DOI: https://doi.org/10.54536/ajec.v4i2.4212 https://journals.e-palli.com/home/index.php/ajec Article Information ABSTRACT Received: December 12, 2024 Accepted: January 16, 2025 Published: April 25, 2025 Volcanic eruption can be a source of heavy metal contamination and such contamination may cause certain risks to the environment and to those who are exposed to the volcanic contents. This study aimed to determine the ecological and health risks from heavy metal exposure in the soil after a volcanic eruption. The agricultural soil samples were collected from Cuenca and Talisay, Batangas and Tagaytay City, Cavite, and were processed for arsenic, cadmium and mercury detection and quantification. The detected metal concentrations were compared to the standard values of the Department of Environmental and Natural Resources for arsenic and United States Environmental Protection Agency for cadmium and mercury while the ecological and human health risks were assessed by computing for the potential ecological risk, hazard quotient and hazard index, respectively. Arsenic was the only heavy metal with high mean concentration in the soil samples of Talisay, Batangas and Tagaytay City, Cavite while cadmium and mercury in the soil were within the acceptable level in the three municipalities. The soil from Talisay, Batangas had two-fold arsenic increase while the samples from Tagaytay City, Cavite had one-fold arsenic elevation. The soil’s post- volcanic eruption’s arsenic contamination was probably due to the direction of the wind during the eruption and groundwater contamination. Low ecological risk and no human health risk were observed despite the recent arsenic concentration in the soil. A two-fold increase in arsenic concentration in the soil will not yet cause ecological and human health risk. Keywords Metal Contamination, Natural Calamity, Soil Pollution 1 De La Salle Medical and Health Sciences Institute, Philippines * Corresponding author’s e-mail: geneveebanta@gmail.com INTRODUCTION Volcanic eruption as a source of heavy metals is less recognized than anthropogenic sources since it is less commonly observed and experienced. Volcanic eruptions caused deleterious effects on humans and the environment, such as burns, respiratory problems, destruction of houses and buildings and damaged crops (Horwell et al., 2020). The gases from a volcanic eruption and the elements in the volcanic ash may contaminate the environment and subsequently affect the health of living organisms. Acid rain is usually observed during and after a volcanic eruption. Its acidity promotes plant uptake of metals (Kim et al., 2010; Jenkins et al., 2015). Most of the local studies about heavy metals in the environment are related to anthropogenic sources (Buagas et al., 2024; Cortez & Ching, 2014). Due to the limited local studies about the assessment of heavy metals after a natural calamity, the study aimed to determine the potential ecological and human health risks from heavy metal exposure in the soil of the municipalities that were affected by Taal Volcano eruption. LITERATURE REVIEW The ashes contain several heavy metals that may alter the normal growth and development of crops and animals. It may even accumulate in these organisms and may affect the food chain. Cadmium, mercury, arsenic and lead were detected in the environment. They can be ingested and taken up by fishes and other living organisms. Increasing environmental concentration of these heavy metals contributes to the accumulation and transfer in the food chain (Martinez et al., 2011). The common routes of entry of heavy metals in the human body are through the inhalation, ingestion and skin penetration (WHO, 2007). Mercury, lead, cadmium and arsenic are the known toxic heavy metals. Mercury has several forms and each form has its own modes of entry in the body. Elemental mercury is the vapor form that may gain access to the brain and kidneys after its initial injury to the respiratory system. Inorganic mercury is the metallic mercury that mainly accumulates in the kidneys. Methylmercury is the most significant form of mercury since it may cause illness through any of the following routes: inhalation, ingestion and skin penetration (ATSDR, 1999). Aside from mercury, arsenic is also a toxic heavy metal that causes health effects after its ingestion. It acute effects are mainly gastrointestinal manifestations such as difficulty in swallowing, vomiting and organ injury. In chronic arsenic exposure, carcinogenic effects are observed in the skin, lungs, kidneys and bladder (US EPA, 2001). Another metal that affects gastrointestinal tract is cadmium. Cadmium may cause gastrointestinal and/or neurologic symptoms when an individual ingests contaminated vegetables and foods (Sharma et al., 2015). Respiratory and renal problems are also detected in individuals with exposure to cadmium. Prolonged cadmium exposure may even lead to cancer since its biological half-life is 30 years (ATSDR, 1990). Pa ge 2 https://journals.e-palli.com/home/index.php/ajec Am. J. Environ. Clim. 4(2) 1-6, 2025 In the Philippines, provinces with significant heavy metal exposure are those that are exposed to mining industries (BanToxics, 2011). Aside from anthropogenic activities, heavy metal exposure after volcanic eruption should also be performed to determine the level of pollutant contamination after the calamity. MATERIALS AND METHODS This study evaluated the ecological and health risks from exposure to mercury, arsenic, and cadmium after the 2020 Taal volcanic eruption. The soil samples were collected from seven locations in Talisay, Batangas, six locations in Tagaytay City, Cavite and one location in Cuenca, Batangas. The latter has the least number of collection sites for soil assessment since it represented the municipalities that are less affected by the 2020 Taal volcano eruption. The soil samples were collected from either the garden or backyard of the house of a resident. A total of 1,000 grams of soil were collected in each location from an approximate depth of 10cm. The samples were placed in a properly labelled polyethylene bag containers. Three replicate soil samples were collected from each location and were sent to a laboratory for processing and quantification of mercury, arsenic and cadmium. The soil samples were stored at room temperature and were dried prior to its processing in a laboratory. The soil samples was processed and underwent cold vapor atomic absorption spectrometry for mercury detection and quantification while Manual hydride generation Atomic absorption spectrophotometry (AAS) and direct air-acetylene flame were used in the detection and measurement of arsenic and cadmium in the soil samples, respectively. The results were presented in mean concentration. Mathematical Expressions and Symbols Ecological Risk Assessment The geoaccumulation index, enrichment factor and potential ecological risk index were used in assessing the ecological risk in the polluted soil. The geoaccumulation index (Igeo) was used to determine the degree of heavy metal pollution or contamination in the agricultural soil (Muller 1969). It was computed using this equation Igeo = log2 (Cn/1.5 Bn) where Cn refers to the estimated concentration of heavy metals n and Bn as the background value in the soil. The background values in the soil were based on DENR AO2019-17 standard values for arsenic and based on the local studies of Posadas et al. (2022) and Nolos et al. (2022) for mercury and cadmium concentration and it is as follows: mercury=2.19 ppm, arsenic=2.0 ppm and cadmium=0 ppm. Meanwhile, the enrichment factor (EF) was also determined, and was identified the degree of metal enrichment in the soil- from natural or anthropogenic activities. It was computed using this equation (Barbieri 2016): EF= (Metal/RE)soil/(Metal/RE)background where RE refers to the value of reference element based on DENR AO 2019-17 standard values for arsenic and the cadmium and mercury concentration of a local study. An EF value of <2 indicated deficiency to minimal enrichment, 240 extremely high enrichment. Since this study has detected a single element in the soil, potential ecological risk factor for a specific element was computed but not the potential ecological risk index. The computation and toxic response factor were based on Hakanson (1980) using the following equation: Potential ecological risk factors (Eri) for a specific element Eri=Tri x Ci f where EEri, potential ecological risk factor for a specific heavy metal i, were computed using the toxic response factor Tri and contamination factor Ci f. The Tri of the heavy metals were as follows: Mercury= 40, Arsenic= 10 and Cadmium= 30. The results were interpreted using the geoaccumulation index, Eri and PERI classification of Hakanson (1980) as seen in Table 1. Table 1: Classification of ecological risk based on geoaccumulation index, potential ecological risk factor and index Igeo value Risk classification Eri value Risk classification PERI value Risk classification Igeo ≤ 0 Practically unpolluted <40 Low risk ≤150 Low risk 0 ≤ Igeo ≤ 1 Unpolluted to moderately 40–80 Moderate risk 150 < PER ≤ 300 Moderate risk 1 ≤ Igeo ≤ 2 Moderately polluted 80–160 Considerable Risk 300 < PER ≤ 600 Considerable risk 2 ≤ Igeo ≤ 3 Moderately to strongly polluted 160–320 High risk PER > 600 High risk 3 ≤ Igeo ≤ 4 Strongly polluted ≥320 Very high Risk 4 ≤ Igeo ≤ 5 Strongly to extremely polluted Igeo > 5 Extremely polluted *Eri and PERI classification of Hakanson (1980) Pa ge 3 https://journals.e-palli.com/home/index.php/ajec Am. J. Environ. Clim. 4(2) 1-6, 2025 Human Risk Assessment Non-Carcinogenic Risk Assessment The noncarcinogenic risk of heavy metals in soil was established by computing for hazard quotient (HQ) and hazard index (HI). HQ was computed using this equation (Chonokhuu et al., 2019): HQ= average daily dose or ADD/RfD or reference dose of heavy metals in mg/kg/day where average daily dose (ADD) referred to the daily dose of heavy metal exposure in contaminated soil while reference dose of heavy metals in mg/kg/day (RfD) referred to estimate of persistent heavy metal exposure by the affected residents. The RfD of arsenic was based on Ma et al. (2019) and the RfD per pathway were as follows: ingestion = 3.00 x 10-4 , inhalation= 5.00 x 10-5 and dermal= 3.00 x 10-4. If the hazard quotient <1, there was no potential health effects but if the value was >1, there was potential health effects from exposure to contaminated soil. Aside from hazard quotient, hazard index (HI) was also computed to determine the total noncarcinogenic risk for each metal. It was computed by adding the hazard quotient for each metal and the study used this equation: HImetal1=HQing + HQdermal + HQinh The hazard quotients for each metal were added and were interpreted as follows: An HI value equal to or less than 1 signified the absence of non-carcinogenic risk from heavy metal exposure in contaminated soil but an HI value of more than 1 indicated that there was a potential noncarcinogenic risks from an exposure to contaminated soil. Carcinogenic Risk Assessment of the Soil Carcinogenic risk from heavy metal exposure in the soil was also determined and it was computed using this equation (Ma et al., 2019): CR= ADD x SF where CR referred to the carcinogenic risk from an exposure to a specific metal while SF was the cancer slope factor of a specific metal. The SF of arsenic based on pathway (Ma et al. 2019) were the following: ingestion= 1.5, inhalation= 15.1 and dermal= 3.66. It was interpreted as follows: (a) CR less than 1 x 10-6 was interpreted as having no carcinogenic risk; (b) a CR value of more than 1 x 10-6 but less than 1 x 10-4 or 1 x 10- 61 x 10-4 indicated that there was significant potential of carcinogenic risk from an exposure in contaminated soil. It was computed using Microsoft excel. RESULTS AND DISCUSSION Heavy Metal Concentration in the Soil The arsenic concentration in the soil of Talisay, Batangas and Tagaytay, Cavite have two- to three-fold increase and one- to two-fold elevation than the reference value, respectively, while the arsenic in the soil of Cuenca, Batangas is maintained within the reference value (Table 2). Meanwhile, cadmium and mercury concentration in the soil of the three municipalities remains within the reference value. Martinez-Villegas et al. (2022) reported that volcanic contents were carried by the wind towards the northeast side of Taal volcano, where Talisay, Batangas is situated, during the 2020 volcano eruption. However, the direction of the wind redirected towards the southwest side of the volcano and it blew lesser ash content than the actual volcanic eruption. The volcanic contents are known to be comprised of elements and even heavy metals that can be harmful to those who will be exposed (Jenkins et al., 2015). Since volcanic contents is blown towards the northeastern side of the volcano during the actual eruption, most of the ashes might have settled on the ground of Talisay, Batangas. Meanwhile, Tagaytay City, Cavite is the municipality that is located beside Talisay, Batangas and it has also been exposed during the eruption. Given this information, these municipalities had been greatly exposed during the volcanic eruption but it is Talisay, Batangas which is likely to have obtained more ashes than Tagaytay City, Cavite. Aside from the direction of the wind, earthquakes were also observed during the eruption and such event may have disturbed the other soil contents. Broken glasswares were observed in some of the collection sites in Talisay, Batangas. Between Talisay and Tagaytay, Talisay has a significantly high arsenic concentration, and these glasswares may have also contributed to the soil contamination. The heat from the environment may react with the glasswares which will trigger the release of arsenic. This concept may also explain the arsenic in the soil of the municipality. Aside from the actual observation of the soil, the groundwater of Talisay, Batangas was discovered to be contaminated by arsenic in the study of Apostol et al. (2022). They discussed that it is possible that these water from wells have access to the volcanic contents. This contaminated groundwater may also have contributed in the arsenic contamination in the soil of Talisay, Batangas as it flows through the land. The direction of the wind, the shaking of the ground during earthquakes and groundwater contamination are the possible sources of the elevated arsenic in the soil of the two municipalities especially Talisay, Batangas. Anthropogenic sources is also a source of metal contamination and may have contributed in the elevated arsenic concentration in the soil of the two municipalities. Fertilizers have been applied in some of the soil collection sites of Talisay, Batangas. Wuana and Okieiman (2011) mentioned that fertilizers and pesticides are made-up of arsenic and such chemicals may take several months before it is eliminated from the land. In the same study, they also discussed that burning of fuels may produce dust particles that contains arsenic. In relation to the study, the soil in some of the collection sites in Talisay, Batangas have been treated with fertilizers. Moreover, the soil collection sites in Talisay, Batangas and Pa ge 4 https://journals.e-palli.com/home/index.php/ajec Am. J. Environ. Clim. 4(2) 1-6, 2025 Tagaytay, Cavite is located at least 50 meters away from the roadside. These factors may have also enhanced the arsenic concentration in the soil of the two municipalities aside from the natural sources. Table 2: Comparison of detected heavy metal concentration in the soil of different municipalities to and its reference values Municipality Arsenic Cadmium Mercury Mean (ppm) Reference value (ppm) Mean (ppm) Reference value (ppm) Mean (ppm) Reference value (ppm) Talisay, Batangas 5.26 2.0 (DENR) <0.03 0.075 (USEPA) <0.08 1.8 (US EPA)Tagaytay, Cavite 3.94 <0.03 <0.08 Cuenca, Batangas 1.92 <0.03 <0.08 Table 3: Comparison of the ecological risk assessment of arsenic-contaminated soil of the affected municipalities of Taal volcano eruption Cuenca Tagaytay Talisay Igeo -0.64 0.40 0.81 Interpretation of Igeo Practically unpolluted Unpolluted to moderately polluted Unpolluted to moderately polluted Enrichment factor (EF) 0.96 1.98 2.63 Interpretation of EF Deficiency to minimal enrichment Deficiency to minimal enrichment Moderate enrichment Potential ecological risk of arsenic (Eri) 9.6 19.75 26.3 Interpretation of Eri Low risk Low risk Low risk Ecological Risk Assessment The soil samples of Tagaytay, Cavite (Igeo=0.40) and Talisay, Batangas (Igeo=0.81) were classified as unpolluted to moderately polluted while Cuenca, Batangas has practically unpolluted soil (Igeo=-0.64). In terms of enrichment factor, the soil of Cuenca, Batangas and Tagaytay City, Cavite were classified as having deficient to minimal enrichment because its enrichment factor is 0.96 and 1.98, respectively, which are less than <2 (reference value). Despite having the minimal differences in other aspects of ecological risk assessment, the soil from all three municipalities has low ecological risk for having arsenic in its soil (Table 3). The metals that were recognized to have moderately to strongly polluted the environment were cadmium, chromium, mercury, lead and arsenic, with their maximum Igeo ranging between 2.7 to 6.2 (Radomirovic et al., 2020). In contrary, Chen et al. (2021) discovered that arsenic concentration from different lands with plant species regardless of abundance and from a soil that is located in residential area demonstrated a non-polluted soil. Moreover, a strong to severe ecological risks is observed in a land with significant vehicular exposure and land manipulation. Like the result of Chen et al. (2021), the finding of this study also has a low ecological risk in arsenic-contaminated soil In this study, the soil samples were collected from a land that is located from either of the following: with minimal vehicular exposure and/or directly from the backyard of a residential house. Moreover, no industrial companies were located nearby or surrounding the collection sites. The study of Radomirovic et al. (2020) showed an increased enrichment factor (2.4 to 12) when compared to the reference value of less than 2 and their soil were collected from an area with industrial leakage. Meanwhile, Ahmad et al. (2021) also detected a moderately heavy metal- contaminated and -polluted soil from a landfill. This signifies that the possibility of heavy metal contamination and pollution in the soil will depend on the location of soil collection and the amount of exposure to chemicals or discharges from industrial companies. In relation to the study, the soil collection site of Cuenca is close to Taal Lake and it would require 1,500 steps before reaching the roadside. Due to the absence of exposure to anthropogenic activities, the enrichment factor in Cuenca, Batangas and Tagaytay City, Cavite demonstrate that the arsenic can be from the earth’s crust. Meanwhile, the moderate enrichment in Talisay, Batangas was due to the natural and anthropogenic sources that have been identified. The identified anthoropogenic sources of arsenic in the soil of Talisay, Batangas were fertilizers, glassware and smoke from vehicles. This study showed that there is still low ecological risk despite an arsenic concentration of up to three-fold elevation in the soil. This demonstrates that such concentration is not yet harmful to the environment. Human Health Risk Assessment Non-carcinogenic risks from an exposure to the soil of the three municipalities demonstrated a hazard quotient and hazard index values of <1 and they signified that an exposure to arsenic-contaminated soil do not pose Pa ge 5 https://journals.e-palli.com/home/index.php/ajec Am. J. Environ. Clim. 4(2) 1-6, 2025 a potential health effect and risk to both adult and children regardless of point of entry in the body (Table 4). Moreover, there is still no possibility for residents to develop cancer from an exposure to arsenic-contaminated soil based on the carcinogenic value of less than 1 from the soil of Cuenca, Tagaytay and Talisay. Table 4: Non-carcinogenic and carcinogenic risk assessments from a possible exposure to arsenic-contaminated soil after the Taal volcano eruption Non-Carcinogenic Risk Age group Cuenca Tagaytay Talisay Hazard index (HI) Adult 1.7 x 10-4 3.3 x 10-4 4.5 x 10-4 Children 1.0 x 10-4 2.1 x 10-4 2.8 x 10-4 Interpretation Absence of non-carcinogenic risks Carcinogenic Risk Adult 1.2 x 10-9 2.4 x 10-9 3.2 x 10-9 Children 3.5 x 10-8 7.2 x 10-8 9.6 x 10-8 Interpretation No chances of carcinogenic risks Health risk from an exposure to arsenic is most likely to occur through ingestion and less of the other pathways. However, it is through ingestion of arsenic-contaminated water that both non-carcinogenic and carcinogenic health risks are identified and most likely to be observed. Children are more exposed than adults especially when they are in an area near a roadside and/or industrial companies and oral route is considered as the common pathway of their exposure (Riaz et al., 2022). Arsenic exposure cannot cause an immediate effect in the health of a living organism, instead, it would require a prolonged exposure to it (Lou et al., 2010). In the study of Apostol et al. (2022), the groundwater was discovered to be contaminated with arsenic. Given this information, the groundwater can be one of the means of human exposure. In terms of arsenic-contaminated soil, the only way for humans to ingest arsenic is through the crops that grew in it. The current arsenic concentration in the soil of Tagaytay City, Cavite and Talisay, Batangas will not yet pose noncarcinogenic and carcinogenic risks which means that it is still not harmful to the exposed residents. CONCLUSION The study discovered that the soil from Cuenca, Talisay and Tagaytay were unpolluted to moderately polluted, have low to moderate contamination and have low potential ecological risk from arsenic. The location of the soil collection contributed to this result. There is lesser possibility for the soil to cause a potential ecological risk, to be polluted and contaminated by arsenic when the soil is taken from an area that is devoid and distant from anthropogenic sources. The soil samples of Talisay had other environmental factors such as fertilizers, broken glasswares and minimal exposure to vehicular smoke that led to moderate enrichment of the soil. Thus, a combination of environmental exposure to chemicals and actual soil collection sites affect the enrichment factor of an area. The soil may not directly cause a non-carcinogenic and carcinogenic risks to a person but we cannot totally eliminate the possibility of arsenic exposure through ingestion of the crops. The current arsenic concentration in the soil of Talisay, Batangas and Tagaytay City, Cavite will not yet cause any significant harm to the environment and to the exposed residents. Acknowledgements I would like to give my deepest gratitude to the barangay health workers and local officials for their assistance during the soil collection; and to Atty. Percival Mendoza and Mrs. Charlene Edgel Mendoza for their help and assistance during the sample collection and other related technical assistance; and to Dr Darylle Cesar Hilapo for his assistance during the ocular inspection. REFERENCES Ahmad, W., Alharthy, R., Zubair, M., Ahmed, M., Hameed, A., & Rafique, S. (2021). Toxic and heavy metals contamination assessment in soil and water to evaluate human health risk. Scientific Reports, 11(1), Article 12489. https://doi.org/10.1038/s41598-021-94616-4 Apostol, G., Valenzuela, S., & Seposo, X. (2022). Arsenic in groundwater sources from selected communities surrounding Taal Volcano, Philippines: An exploratory study. Earth, 3(1), 448–459. https://doi.org/10.3390/ earth3010027 Agency for Toxic Substances and Disease Registry. (1990). Case studies in environmental medicine: Cadmium toxicity. https://www.atsdr.cdc.gov Agency for Toxic Substances and Disease Registry. (1999). Public health statement: Mercury (CAS#: 7439-97- 6). https://www.atsdr.cdc.gov Ban Toxics. (2011). Chasing mercury: Measuring mercury levels in the air across the Philippines. https://www.bantoxics. org Barbieri, M., Sappa, G., & Nigro, A. (2015). Soil contamination evaluation by enrichment factor (EF) and geoaccumulation index (Igeo). Senses Sci. https:// iris.uniroma1.it/retrieve/e383531e-668d-15e8-e053- a505fe0a3de9/Barbieri%20et%20al.%2C%202015. pdf Pa ge 6 https://journals.e-palli.com/home/index.php/ajec Am. J. Environ. Clim. 4(2) 1-6, 2025 Buagas, D., Megraso, C., Namata, J., Lim, P., Gatus, K., & Canete, A. (2014). Tracking quicksilver: Estimation of mercury waste from consumer products and subsequent verification by analysis of soil, water, sediment, and plant samples from the Cebu City, Philippines, landfill. Environmental Monitoring and Assessment, 187(138). https://doi.org/10.1007/ s10661-014-3577-9 Chen, W., Zhu, K., Yankun, C., Yuelin, W., & Yingping, L. (2021). Distribution and ecological risk assessment of arsenic and some trace elements in soil of different land use types, Tianba Town, China. Environmental Technology & Innovation, 22, 102041. https://doi. org/10.1016/j.eti.2021.102041 Chonokhuu, S., Batbold, C., Chuluunpruev, B., Battsengel, E., Dorjsuren, B., & Byambaa, B. (2019). Contamination and health risk assessment of heavy metals in the soil of major cities in Mongolia. International Journal of Environmental Research and Public Health, 16(14), 2552. https://doi.org/10.3390/ ijerph16142552 Cortez, L., & Ching, J. (2014). Heavy metal concentration of dumpsite soil and accumulation in Zea mays (corn) growing in a closed dumpsite in Manila, Philippines. International Journal of Environmental Science and Development, 5(1), 77–80 Department of Environmental and Natural Resources. (2019). DENR Administrative Order no. 2019-17: Chemical control order for arsenic and arsenic compounds. h t tps ://chemica l .emb.g ov.ph/w p-content/ uploads/2019/11/DAO201917Arsenic.pdf Hakanson, L. (1980). An ecological risk index for aquatic pollution control: A sedimentological approach. Water Research, 14, 975–1001. Horwell, C., Baxter, P., & Kamanyire, R. (2020). Health impacts of volcanic eruption. In Volcanic health hazards (pp. 15–29). Cambridge University Press. https://doi. org/10.1017/CBO9781316276273.015 Jenkins, S., Wilson, T., Magill, C., Miller, V., Blong, S., Marzocchi, W., & Boulton, M. (2015). Volcanic ash fall hazard and risks. In Volcanic health hazards (pp. 5–15). Cambridge University Press. https://doi. org/10.1017/CBO9781316276273.005 Kim, A., Kim, J., Ko, M., & Kim, K. (2010). Acid rain impact on phytoavailability of heavy metals in soil. Geosystem Engineering, 13(4), 133–138. Lou, W., Lu, Y., Wang, T., Hu, W., Jiao, W., Naile, J., Khim, J., & Giesy, J. (2010). Ecological risk assessment of arsenic and metals in sediments of coastal areas of northern Bohai and Yellow Seas, China. AMBIO, 39(5), 367–375. Ma, Q., Han, L., Zhang, J., Zhang, Y., Lang, Q., Li, F., & Han, A. (2019). Environmental risk assessment of metals in the volcanic soil of Changbai Mountain. International Journal of Environmental Research and Public Health, 16(20), 3903. https://doi.org/10.3390/ ijerph16203903 Martinez, F., Mijares, M., & Galera, T. (2011). Assessment of the water quality of Mamba river of Mts. Palay Palay/Mataas na Gulod, Southern Luzon, Philippines. Laguna Lake Development Authority. http://llda.gov.ph/ wp-content/uploads/dox/waterqualityrpt/rivers/ sb.pdf Martinez-Villegas, M., Reniva, P., Sanico, L., Loza, A., Seda, R., Doloiras, D., & Pidlaoan, A. (2022). Perspectives on the 12 January 2020 Taal Volcano eruption: An analysis of residents’ narrative accounts. Frontiers in Earth Science. https://doi.org/10.3389/ feart.2022.923224 Muller, G. (1969). Index of geo-accumulation in sediments of the Rhine River. GeoJournal, 2(2), 108–118. Nolos, R., Agarin, C., Domino, M., Bonifacio, P., Chan, E., Mascarenas, D., & Senoro, D. (2022). Health risks due to metal concentration in soil and vegetables from the six municipalities of the island province in the Philippines. International Journal of Environmental Research and Public Health, 19(3), 1587. https://doi. org/10.3390/ijerph19031587 Posadas, R., Salting, A., Yamas, J., & Patayon, E. (2022). Mercury concentration of the soil profiles of the abandoned mercury mine in Sta. Lourdes, Puerto Princesa City, Palawan, Philippines. Philippine Journal of Science, 151(3), 895–899. Radomirovic, M., Cirovic, Z., Maksin, D., Bakic, T., Lukic, J., Stankovic, S., & Onjia, A. (2020). Heavy metals in the soil at a former painting industry facility. Frontiers in Environmental Science, 8, 560415. https://doi. org/10.3389/fenvs.2020.560415 Riaz, R., Murtaza, G., Farooqi, Z., Ali, S., Aziz, H., Mahboob, S., Al-Ghanim, K., Owens, G., Ahmad, H., & Riaz, U. (2022). Assessment of arsenic contamination in groundwater and associated human health risk. Sustainability, 14(19), 12460. https://doi. org/10.3390/su141912460 Sharma, H., Rawal, N., & Mathew, B. (2015). The characteristics, toxicity, and effects of cadmium. International Journal of Nanotechnology and Nanoscience, 3, 1–9. United States Environmental Protection Agency. (2001). Exposure and health effects. https://www.who.int/ water_sanitation_health/dwq/arsenicun3.pdf World Health Organization. (2007). Natural disasters: Coping with the health impact. https://www.eird.org/ isdr-biblio/PDF/Natural%20disasters%20coping. pdf Wuana, R., & Okieimen, F. (2011). Heavy metals in contaminated soils: A review of sources, chemistry, risks, and best available strategies for remediation. ISRN Environmental Chemistry, 2011, 402647. https:// doi.org/10.5402/2011/402647