Health Risk Assessment of Trace Metals in the Vicinity of an Abandoned Mercury Mine in Puerto Princesa City, Philippines

Abstract

Abandoned mines pose high risks to human health and the environment due to the disturbed and exposed metal-laden soils and sediments. In this study, soils and sediments in an abandoned mercury (Hg) mine in Puerto Princesa City, Philippines were analyzed to assess the potential adverse health effects of the exposure to trace metals associated with the mine wastes. A total of 63 soil and sediment samples were collected in the area and analyzed for Hg concentration using a direct Hg analyzer and inductively coupled plasma–mass spectrometry (ICP-MS) for other trace metals. Analysis results showed that aside from Hg, there are anomalous concentrations of Ni (nickel), Cr (chromium), and Mn (manganese) in the area brought by the value of the mineralogy of the ores that were mined. The measured trace metal concentrations, together with the United States (US) Environmental Protection Agency’s (EPA) exposure parameters and the US Department of Energy’s (DOE) toxicity values were used to calculate the dose contacted from different exposure pathways. The result of the health risk assessment showed that Hg was considered as the main contributor of non-carcinogenic risk in the area with a hazard index of > 1 for both children and adults. Inhalation of Hg vapor from the soils and sediments is found to be a significant addition to the health risks in the area. Other trace metals such as Co (cobalt), Fe (iron), Ni (nickel), and Tl (thallium) were calculated with a hazard index greater than 1, which poses a health risk to children due to the ingestion pathway. All carcinogenic trace metals assessed were below the guidance value, indicating no significant carcinogenic health risks for both adults and children in the area. This work serves as an initial step of the country in the assessment of the risks to human health and the environment brought by Hg contaminated areas, as stated in the Minamata Convention on Mercury.

Ecological and health risks from heavy metal sources surrounding an abandoned mercury mine in the island paradise of Palawan, Philippines

“…The mean CR contribution of the heavy metals to LCR for both adults and children is Cr (91.8%) > As (8.1%) > other heavy metals (0.1%). The results of the health risk analyses differ significantly from the work of [ 43 ] that discounted in their calculations the carcinogenic effects of Co, Cr, and Ni. Surprisingly, it was found that these three heavy metals contribute 92% to the LCR for both adults and children.…”

“…Ultramafic rocks like the harzburgites have Cr and Ni concentrations reaching 2980 mg kg −1 and 10,900 mg kg −1 , respectively [ 41 , 42 ]. Meanwhile, Mn is related to the occurrence of red chert and dark manganiferous chert located northeast of the study area [ 43 ]. Majority of PC3 or the natural source is apportioned to PQMI pit lake and Tagburos River.…”

Modelling the Origin, Fate, and Ecological and Health Impacts of Heavy Metals from an Abandoned Mercury Mine in a Paradise Island in the Philippines

“…The results of our health risk analyses differ significantly from the work of [45] that didn't account the carcinogenicity of Co, Cr, and Ni which we found to cause high to very high risk CR to both adults and children. As the hazards caused by multiple heavy metals is also interactive, their failure to account the carcinogenic effects of all the possible metals through the LCR led them to conclude that there is no overall risk for the population to develop cancer that we've shown here otherwise.…”

“…The area surrounding the abandoned mine is home to more than 12,200 people in 2015. Our findings suggest a very strong potential to cause adverse health effects to residents due to heavy metal exposure which is supported by a recent work of [45]. Here, we present some key recommendations that the government through the Department of Environment and Natural Resources (DENR) and the local government of Palawan can adopt to mitigate the harmful effects of the heavy metals to the environment and the population:  Land use plan in the affected areas should be reviewed to mitigate potential harm to the community without affecting key sources of employment.…”

“…Ultramafic rocks like the harzburgites have Cr and Ni concentrations reaching 2980 mg kg -1 and 10,900 mg kg -1 , respectively [43,44]. Meanwhile, Mn is related to the occurrence of red chert and dark manganiferous chert located northeast of the study areas [45]. The fifth cluster consisting of Hg and other heavy metals can be attributed to calcine from historical Hg mining and processing.…”