Environmental pollution caused by mercury (Hg) has been of much concern in recent times particularly in areas where artisanal gold mining is predominant. Sources of mercury are natural sources (weathering of rocks, eroded soil particles, volcanic emissions, forest fires, plant litters etc) and anthropogenic sources (industrial emission, vehicular emission, discharge from mining, agricultural and medical waste) of which anthropogenic activities contributes 50–75% of global emission (Nazarpour et al., 2018; Solgi et al., 2014).
Mercury is present in water, sediments, soil, dust, and the atmosphere (Cobbina et al., 2015; Coker et al., 2022; Nugraha et al., 2023) and in the forms of gaseous elemental Hg, Inorganic Hg2+ compounds and methyl mercury (the most toxic form of organic mercury). Mercury, particularly methyl mercury, is one of the most toxic heavy metals studied in recent times due to its adverse health effects in humans and the environment (Sun et al., 2013). High mercury levels have serious adverse effects on the brain, liver, and heart muscle (Frazin et al.,2008). As a result, it is of higher concern to international organizations such as World Health Organization (WHO), Food and Agricultural organization (FAO) and United Nation Environmental Programme (UNEP) (Nazarpour et al.,2018).
Artisanal and small-scale gold mining (ASGM) as an anthropogenic source is a major contributor of Hg (UNEP, 2013). Globally, 37% of anthropogenic Hg emissions come from ASGM (Nakazawa et al., 2016). Many researchers have recorded elevated levels of Hg in soil in artisanal and small-scale gold mining communities. (Bortey-Sam et al., 2015; Gyamfi et al., 2020; Pateda et al., 2021; Addai-Arhin et al., 2022; Coker et al., 2022). In Dunggilata (Indonesia), 63–577 mg/kg of Hg in dust was recorded (Pateda et al., 2021).
Ghana is one of the major users of Hg for ASGM in Africa. Despite the ban on Hg stemming by government from its negative effect on the environment (Addai-Arhin et al., 2022), it is still used in Ghana by illegal miners due to lack of direct engagement of miners, lack of alternative source of income, high value of gold in the market, low cost of Hg and limited knowledge about mercury usage. In gold extraction, 2 g of mercury is used in forming an amalgam with 1 g of gold (Gyamfi et al., 2022). The amalgam is heated to get pure gold. This is usually performed on the field, gold shops and in and around various residences. The impact of Hg pollution may affect the miners and nearby communities. Mercury contamination through mining is slow but spreads with time.
Dust is a heterogenous mixture of organic and inorganic particles which can absorb heavy metals including mercury (Cheng et al., 2018). Adults spend about 88% while children spend 71–79% of their time indoor (Tashakor et al., 2022). Mercury elevation in indoor dust depends on outdoor dust and human activities indoor. Mercury in dust has recently been studied, particularly in the developed countries (Sun et al., 2013; Nazarpour et al., 2018; Zhang et al., 2019).
Although a lot of studies have focused on Hg pollution in air, food, and water but not dust in ASGM. Much focus has been on other heavy metals (As, Cr, Cu, Fe, Mn, Ni, Pb, and Zn) in the urban areas notably in Ghana, not Hg (Blankson-Arthur et al., 2011; Gordon et al., 2012). This is first study of Hg in indoor and outdoor dust in Artisanal small gold mining area in Ghana. It is necessary to understand further Hg contamination in outdoor dust and indoor dust in residential areas in ASGM communities particularly Amansie West district in the Ashanti Region of Ghana.
Mercury exposure through ingestion, inhalation of re-suspended dust, dermal contact, and inhalation of Hg vapour of polluted dust is likely to pose health risks to residents, particularly children(Sun et al., 2013). As such the current study aimed to investigate the levels of Hg in outdoor and indoor dust in two mining communities in Amansie West District in Ghana, to assess the health risks (Hazard Quotient) of Hg among residents of the area and to estimate the extent of contamination using hazard index (Igeo). Findings from this study would inform the government of the need to alleviate Hg pollution in mining communities and reduce harm to humans, particularly children.