Abstract:
Background: Mercury is a highly dangerous neuro-toxicant, affecting over 2 million people in Tanzania. High exposures in artisanal gold mining have significant health and environmental impacts. Burning of mercury amalgamate is of great concern as it emits mercury directly to the atmosphere affecting miners and nearby residents. We assessed environmental and occupational exposure to mercury in miners and their families from Handeni District, north-east Tanzania.
Objectives: We aimed to determine mercury exposure levels among miners and their families by testing urine, blood and hair, as well as determining the relationship between exposure biomarker and signs and symptoms of mercury intoxication. We also aimed to determine the concentration of mercury in water and vegetables, in the areas surrounding the gold mining community. Moreover, we aimed to assess the health effects of mercury exposure on miners and their families
Methods: A cross sectional descriptive study was conducted among 292 miners and their families. Interviews and medical examinations were conducted on all participants. A sample of 30 participants with history of mercury use, provided hair, urine and blood, residential ground water and vegetable samples for mercury analysis by Inductively Coupled Plasma Optical Emission Spectrometry. Data analysis was done using Epi-Info.
Results: We enrolled 292 participants with a mean age of 31.8 years.. The mean mercury levels in urine and blood from selected participants were 46.3µg/L and 14.5µg/L respectively. Out of 21 urine samples, 10 (47.6%) exceeded the maximum acceptable level of 50 µg/L provided by the World Health Organization (WHO). Additionally, out of 25 blood samples, 13 (52%) exceeded the WHO normal range of 5- 10µg/L. All hair samples were below the detection limit of 0.01ppm. Miners engaged in amalgamation and burning of amalgam had higher mean mercury levels in urine (53.7µg/L, p=0.02) and blood (27.6µg/L, p= 0.6). Mercury levels in groundwater were below Tanzanian standards of 1µg/L. Tremor of the eyelid (30%) was significantly higher (p<0.005) in miners than non-miners. Other signs recorded on examination of miners were blue line in gums (34%), blue coloured ring in periphery of iris (11%), dysmetria (9%), gingivitis (7%), intention tremor (5%), decreased mental labial reflex (5%) and decreased Babinski reflex (5%)
Conclusion and recommendation: High mercury concentrations in urine and blood were found in mining community of Handeni District. Miners, who are known to have a high occupational exposure, have higher mercury concentrations than non-miners. In addition; signs of mercury intoxication were also identified in miners. Immediate efforts should be directed into reducing occupational and residential exposures to mercury in communities near gold mines. Larger studies should be carried out to better characterize exposures found while control measures are implemented
