Table 3 Toxic Hazards

Various toxicological hazards occur in different types of mining. 50–100 million women, infants, children and men in ASM settings are exposed to mercury [18, 19]. Concentrations of mercury in biological matrices of individuals living in mining settings are measured to be at toxic levels [20, 21]. Processing gold after extraction entails the smelting of amalgams, hence, research has shown that especially in artisanal and small-scale gold mining exposure to mercury is high among miners and communities [22, 23]. Thereby, highly toxic elementary mercury vapor is inhaled [19]. Consequently, several adverse health effects, especially neurological effects are observed [24, 25]. An estimated 25 to 33% of ASGM miners show the symptoms of chronic mercury vapor intoxication, meaning 3.3–6.5 million miners globally [20]. In ASGM 10 to 19 million miners are exposed to mercury [26]. The WHO identifies elemental mercury as hazardous to the nervous system [27]. In particular mercury vapor, as seen in ASGM, is also harmful to the kidney, the digestive and the immune system, potentially causing fatal organ failures. Additionally, behavioral and neurological effects are described after any mode of exposure to mercury [4].

The WHO [10] points out that lead poisoning in mining areas increases mortality and morbidity rates. Varying levels of lead, determined by geological factors, can be found in former and current ASM settings. In Kabwe/Zambia a former zinc-lead mine is a constant source of lead exposure for the children playing and living nearby the old tailing hill, thousands of children have very high lead levels in their blood, so the exposure from the uncovered tailing hill and the lead containing soil in the settlements have to be stopped urgently [28,29,30,31]. Scavengers are still exploring the old mining side and expose themselves as well [28]. Since 2010, several authors describe that children in a gold mine in Nigeria are highly intoxicated; approximately 400 fatalities due to lead poisoning among those children were reported [32,33,34,35,36,37,38]. Exposure to lead at many toxic sites in Low- and Lower-middle-income countries is a well-known risk factor for the cognitive development during pregnancy [39], an “estimated 820,000 women of childbearing age are at risk for lead exposure at these sites” [40]. Lead is an IARC 2A carcinogen with strengthening evidence more recently [41].

Arsenic is released from mining and processing. Arsenic is an IARC 1 carcinogen depending on the route of exposure and species associated with skin, bladder, lung, kidney, and liver cancer [42]. Arsenic can adversely affect adults and children. Depending on exposure levels and circumstances, various health consequences are observed, such as skin rashes and pulmonary and cardiovascular diseases. Children and infants exposed to arsenic frequently develop neuro-developmental and -behavioral disorders [43, 44].

Cadmium is a by-product of mining. Cadmium is an IARC 1 carcinogen, mainly associated with lung cancer, but also with cancer of the kidney and the prostate [45]. Additionally cadmium deteriorates the renal function, immune responses, cardiovascular and skeletal health [46].

The demand for cobalt sharply increases due to technological developments. Batteries used in novel electric vehicles and other technologies require cobalt as an essential resource. Mines in the Katanga Copperbelt in the Democratic Republic of Congo (DRC) are producing 60% of the metal used worldwide [47]. 15–30% are estimated to originate from ASM [47,48,49]. Environmental pollution in mining areas and lack of separation of living and working spaces, sets not only miners themselves but entire communities at risk of experiencing adverse health effects. Cobalt exposure was found to be correlated with dust exposure causing long-term damage of inter alia, the cardiovascular- and pulmonary system [50]. Additionally, DNA damage of children living in mining areas in the DRC was found, indicated by high levels of 8OHdG in urine biomonitoring [47]. Indication exists that birth defects of children are related to cobalt and copper mining [51]. Increased sustainability of cobalt mining in terms of environment and health is urgently needed to protect the most vulnerable. Not counting as a so-called blood metal, which are related to high rates of conflict and violence, cobalt nowadays remains unregulated. Unlivable and hazardous conditions cannot continue to affect an increasing number of individuals who are supplying minerals which are classified as essential to sustain western economies [47].

Cyanide is used as an alternative to mercury in ASGM and adversely affects respiratory and cardiovascular health and is known to adversely affect the central nervous system [52]. Specific data and knowledge about the health risks related to cyanide exposure in mining settings is lacking [53].