Exposure of Small Scale Gold Miners in Prestea to Mercury, Ghana

Abstract

Background: Mercury is commonly used in Artisanal Small-Scale Gold Mining (ASGM) to amalgamate gold. Mercury use in ASGM is a global public health problem, since it is the world’s fastest source of mercury contamination. Mercury is toxic even at low concentration and exposure is of great concern since it is a potent neurotoxicant. Mercury poisoning among small scale gold miners has been observed in many small scale gold mining regions across the world. ASGM is a rapidly growing industry in Prestea where miners handle mercury without personal protective equipment (PPE). This study seeks to assess occupational exposure of small scale gold miners in Prestea to mercury. Method: Morning urine samples were collected from 343 consenting small scale gold miners at their work sites in Prestea. A structured questionnaire was used to collect information from the miners. A work place assessments and interviews were conducted at the small scale gold mines. Urine samples were analyzed at the laboratory for elemental mercury. Univariate analysis was expressed as frequencies, percentages, mean±SD, tables and figures. Association between mercury exposure; adverse health effects and occupational exposure was determined at 95% CL. Results: Of the 343 participants urine samples, 160(46.65%) of them exceeded the guideline value for individuals not occupationally exposed to mercury (<5.0ug/L). Of the 160 (46.65%) participants exposed to mercury, 122 (35.57%) of them, their urine mercury level was between (5.00-20.00ug/L), while the remaining 38(11.08%) had urine mercury level (>20.00ug/L). There were no significant association between mercury exposure; and complaints of skin rashes (χ 2 =3.49, p=0.062), red eyes (χ 2 =3.22, p=0.073), and metallic taste (χ 2 =3.72, p=0.054). Complaints of numbness, however, were significantly associated with mercury exposure among participants who have previously worked at other small scale gold mines before moving to Prestea (χ 2 =4.96, p=0.026). Standing in a pool of water or stream whiles working at the mining site (OR: 1.31, 95% CI: 0.81-2.09), sucking of excess mercury from the amalgam for re-use with the mouth (OR: 1.37, 95% CI: 0.78-2.39) and amalgamating with mercury (OR: 2.14, 95% CI: 0.77- 5.94) were associated with mercury exposure; however, these were not significant. Majority 335 (97.7%) had no occupational safety training in handling mercury and the use of PPE among the participants was very low. Retorts for burning amalgam was not found at mining sites visited. Conclusion: Small scale gold miners in Prestea are experiencing mercury exposure in excess of occupational exposure guidelines, and are at risk of mercury intoxication. Prestea Huni-Valley District Health Directorate, the Environmental Protection Agency and the Minerals Commission should organize regular medical screening and occupational safety training in handling mercury; and also mobilize retorts for burning gold amalgam for the small scale gold mining communities in Prestea.