Mercury Exposure Among Artisanal and Small-Scale Gold Miners in Four Regions in Uganda

Abstract

Background. Artisanal and small-scale gold mining is a human health concern, especially in low-income countries like Uganda due to the use of mercury (Hg) in the mining process. Objective. The aim of the present study was to assess Hg exposure among artisanal and small-scale gold miners in Uganda through biologic monitoring parameters and Hg-related clinical manifestations. Methods. A cross-sectional study was conducted from June to July 2018 among 183 miners from Ibanda (Western region), Mubende (Central region), Amudat (Karamoja region) and Busia (Eastern region) in Uganda. An interviewer-administered questionnaire and health assessment were used to collect socio-demographic, exposure and self-reported Hg poisoning symptoms. In addition, 41 urine, 41 blood and 26 environment samples were assessed. Descriptive statistics, Kruskal-Wallis test and Wilcoxon signed-rank test for comparison of Hg levels in urine and blood among miners were performed while logistic regression was used to assess associations between exposure and Hg poisoning-related symptoms. Results: The miners ranged from 15 to 65 years old and were primarily male (72.6%). The majority (73.3%) had worked directly with Hg for an average duration of 5.3 years. Symptoms associated with working directly with Hg included chest pain (odds ratio (OR)=9.0, confidence interval (CI)=3.3 to 24.6), numbness (OR=8.5, CI=2.1 to 34.4), back pain (OR=6.2, CI= 2.2 to 17.5), fatigue and stress (OR=5.4, 2.0 to CI=14.9), headache (OR=4.7, CI=1.9 to 11.3), dizziness (OR=3.8, CI=1.5 to 9.7) joint pain (OR=3.2, CI=1.3 to 8.3) and respiratory problems (3.2, 1.0 to 10.1). Statistically significant differences in Hg levels with p-values less than 0.05 were observed across district, gender and type of work. Mubende had the highest blood and urine levels (136 μg/l and 105.5 μg/l) in comparison with Busia (60 μg/l and 70.6 μg/l) and Ibanda (43 μg/l and 58 μg/l). Females (84.7 μg/l), panners (109 μg/l) and those with knowledge of occupational health and safety measures (95.6 μg/l) reported higher levels of Hg in urine. The average levels of Hg in water and soil samples were 23.79 μg/l and 0.21 μg/l, respectively. Conclusions. Variation in Hg levels were attributed to varied duration of exposure across geographical sites. There was considerable exposure to Hg as indicated by both clinical manifestations and biologic parameters among miners in Uganda with Hg in urine exceeding the recommended thresholds. Participant Consent. Obtained Ethics Approval. Ethical approval was obtained from the Makerere University School of Health Science Institutional Review Board (reference number SHSREC REF 2018–2019) and Uganda National Council for Science and Technology (reference number SS 4577) Competing Interests. The authors declare no competing financial interests.

Mercury Exposure and Its Health Effects in Workers in the Artisanal and Small-Scale Gold Mining (ASGM) Sector—A Systematic Review

“…The subsequent evaluation of the remaining 103 full-texts resulted in the exclusion of 84 articles due to their failure to fulfil the following eligibility criteria: study population ( n = 55), outcome ( n = 16), exposure ( n = 6), study design ( n = 4), language ( n = 2) or context ( n = 1). Eventually, 19 publications were included in this systematic review [ 43 , 44 , 45 , 46 , 47 , 48 , 51 , 52 , 53 , 54 , 55 , 56 , 57 , 58 , 59 , 60 , 61 , 62 , 63 ] ( Figure 1 ).…”

“…The included studies also differed in terms of data collection and diagnostic procedures [43][44][45][46][47][48][51][52][53][54][55][56][57][58][59][60][61][62][63]. The data were mainly collected through measurements of defined parameters [43][44][45][46][47][48][51][52][53][54][55][56][57][58][59][60][61][62][63], surveys [43][44][45][46][47][48][51][52][53][56][57][58]…”

“…The selected articles included 18 cross-sectional studies [43][44][45][46][47][51][52][53][54][55][56][57][58][59][60][61][62][63] and 1 case series [48], whose publication years ranged from 1993 to 2020 [43][44][45][46][47][48][51][52][53][54][55][56][57][58][59][60][61][62][63]. The following geographical regions were covered:…”

“…A statistically significant positive association was observed between the mercury values in urine with problems to grab as well as with thoracic pain [56]. Uganda Wanyana et al described that observed symptoms showed a significant different distribution according to sex: males reported more frequently about headache, while females reported more frequently about psychiatric disorders or memory problems [57]. In addition, mercury exposure was statistically significantly associated with neuro-psychological disorders (such as headache, numbness, dizziness), certain kinds of pain and respiratory symptoms [57].…”

Documenting Environmental Contamination in Vulnerable Populations

“…We are proud to have published articles from countries very underrepresented in the scientific literature, including Algeria, 7 Armenia, 8 Belize, 9 Botswana, 10 Jamaica, 11 – 14 Liberia, 15 Mongolia, 16 Myanmar/Burma, 17 , 18 Nepal, 19 , 20 Sri Lanka, 21 Sudan, 22 , 23 Tajikistan, 24 Tanzania, 25 – 27 Togo, 28 , 29 Uganda 30 – 33 and Zimbabwe. 34 …”