THE NEUROTOXIC EFFECTS OF MERCURY VAPOR EXPOSURE FROM ARTISANAL AND SMALL- SCALE GOLD MINING Mackenzie Kennedy ‘16 ES366: The Environment and Human Health,Environmental Studies Program, Colby College POLICY: The Minamata Convention on Mercury ratified October 10 th 2013 Goal: reduce global mercury emissions in the interest of human and environmental health  Bans mercury in battery and gold mining but not in artisanal and small-scale gold mining  Encourages ASGM countries to reduce their own use, without providing targets or dates Conclusion: Considers the health of populations globally exposed to mercury but fails to enforce measures protecting vulnerable populations who face significantly higher exposures within the ASGM trade (1). MERCURY VAPOR EXPOSURE LEVELS: Cross-sectional assessment of 103 residents in an artisanal gold mining town of Huaypetue, Peru in July 2010 US EPA reference dose urine total mercury levels: 5.8 ųg/L assumed level without adverse health effects; >5.8 ųg/L risk of adverse health effects  13 participants (13%) reported having kidney dysfunction or a neurological disorder  Those who heated gold amalgams had a 4.32 higher total urine level (8.81>4.49) and a risk of adverse health effects MERCURY VAPOR MAPPING: Mercury mapping data analysis systems can be used to characterize the behavior of mercury vapors emissions in urban areas, monitor the distribution of human exposure, and increase awareness of the health hazard produced by artisanal gold shops and urban mercury emissions that indirectly affect urban residents living in close proximity but not involved in the amalgamation processing (5). Average concentrations measured by mobile mercury vapor analyzers:  On average, concentrations in the residential area of Andacollo exceed WHO tolerable levels (>0.2 ųg m -3 ) (World Health Organization, 2000) and in the urban core of Segovia they exceed the WHO hazard level 1 ųg m -3. As a result, the average resident of these areas is at risk of mercury poisoning.  During pilot testing of the EPA and Argonne National Laboratory’s Gold Shop Mercury Capture System (MCS), gold shops that did not have the MCS technology installed had mean ambient mercury vapor concentrations that were five to 20 times higher than those shops that had the mercury control system installed (8). Average mercury concentrations in the streets of Segovia, Colombia, 1.26 ųg m -3 (5) Average mercury concentrations in the streets of Andacollo, Chile ųg m - 3. The white dashed line marks the limits of the urban area used to compute average mercury concentration and encloses all gold shops in this study. Satellite image courtesy of Google Earth, (5). NEUROCOGNITIVE DEFICITS AND CHILD LABOR:  Many children in ASGM countries come from households living on $1-2 a day, pressuring them to miss school to either work in tunnels, pan ore, or even burn amalgam.  In a biomonitoring study of 166 children in Indonesia and Zimbabwe, the source of mercury exposure was liquid mercury used to bind gold, forming an amalgam.  Matchbox testing for neuromotor functions: Mean values: 17.2 s/21.3 s/ 20.4 s, Extreme: none of 52 control children needed longer than 29 seconds to sort the 20 matches; Burdened group lasted up to 43 s.  Pencil tapping test for intentional tremor and coordination: Mean values: 53.7 s/ 47.6 s/ 48.7 s, slowest child of control group tapped 27 times with a pencil on the paper within 10 seconds; The lowest of the burdened group just 17 times.  In Zimbabwe, 4 of 14 children living in mercury exposed areas were intoxicated (29%) and 16 of 29 children working with mercury were found to be intoxicated (55%) *diagnosis of chronic mercury intoxication based on the UNIDO health assessment protocol (3). FUTURE RESEARCH/ACTION:  Eliminate amalgam burning and processing centers from populated areas (3)  Expand the EPA and Argonne National Laboratory’s Gold Shop Mercury Capture System (MCS), as tests indicate the technology can reduce airborne mercury in gold shops by 80% (8).  Maintain a continual presence of trainers and field technicians to monitor and encourage proper installation, usage and maintenance in the short term, and to train municipal officials in long-term regulation enforcement, working with national governments in meeting national action plans on mercury reduction and elimination from ASGM (5).  Determine DALYs for the neurotoxic effects of mercury vapor, specifically for children living in ASGM areas whose productivity later in life is a function of neurocognitive development EXPOSURE MECHANISM: Amalgam is heated, and the smelting amalgam releases elemental mercury vapor in addition to the wanted gold through tailings (2). Pictured above: An amalgamation mill in Colombia where miners are directly exposed to highly toxic amounts of mercury vapor INTRODUCTION:  Artisanal and Small-Scale Gold Mining (ASGM) is the world’s second largest source of atmospheric mercury pollution behind coal combustion (UNEP 2012).  An estimated 10 to 15 million people in 70 countries work in the ASGM trade and are exposed to the toxic effects of mercury from an inexpensive yet effective gold processing technique (7). NEUROTOXICITY OF MERCURY VAPOR:  As a highly lipophilic substance, mercury vapor crosses the blood-brain barrier easily, targeting the cerebellum in the brain. Zero-valent mercury vapor is rapidly oxidized to Hg ++ -ions in human blood and tissues. Mercury is trapped in the brain as the formed Hg ++ ions cannot diffuse easily back from the brain to the blood due to the blood-brain barrier (Drasch et al., 2004) (2). Adult mercury exposure produces localized damage to the cerebellum, visual cortex, and motor strip, leading to visuospatial problems and effects on executive functioning, mood, and memory. Early life exposure, however, is most harmful because increased exposure can damage the whole brain. In its organic form, methylmercury is considered the most toxic mercury form among children, who may experience neurodevelopment deficits, IQ losses, and delayed speech from exposure.  While pregnant women and children experience the greatest risk of neurotoxic effects from methylmercury exposure, these vulnerable populations also participate in the ASGM trade and are at a greater risk of neurotoxic effects from amalgam-induced mercury vapor exposure (9). BIBLIOGRAPHY: *please see separate source list provided *