Tremor among Artisanal Small-scale Gold Mining Workers and its Related factors in Indonesia’s West Nusa Tenggara and Banten Provinces

Background. Artisanal and small-scale gold mining (ASGM) workers are at risk of mercury exposure, particularly through inhalation of mercury vapor during gold amalgam smelting. Tremor is one of the earliest and most common neurological manifestations of mercury intoxication; however, its prevalence and associated risk factors among Indonesian ASGM workers remain poorly characterized. 

Objective. This study determined the prevalence of tremor among ASGM workers and identified factors associated with its occurrence.

Methods. A cross-sectional study was conducted among ASGM workers in West Nusa Tenggara and Banten Provinces, Indonesia. Eligible participants had worked in ASGM for at least three months. Tremor was assessed using the finger-to-nose test performed by trained physicians. Urinary mercury concentration, measured from first-morning spot urine samples using inductively coupled plasma–mass spectrometry (ICP-MS), was used as a biomarker of mercury exposure. Demographic, occupational, and exposure-related variables were collected using the WHO-UNEP mercury health assessment questionnaire. Associations between tremor and potential risk factors were analyzed using Chi-square or Fisher's exact tests, while urinary mercury levels between groups were compared using the Mann-Whitney test.

Results. A total of 209 ASGM workers were included in the analysis. The prevalence of tremor was 8.6% (18/209), with most cases classified as mild to moderate. Thirty-four point nine percent of workers had urinary mercury concentrations exceeding the Biological Exposure Index (>20 µg/g creatinine), while 7.2% had levels ≥100 µg/g creatinine. Workers aged >40 years had significantly higher odds of tremor compared with those aged <32 years (OR = 5.09, 95% CI: 1.05–24.48; p = 0.02). No significant associations were observed between tremor and smoking status, duration of employment, occupational exposure category, pesticide handling, or urinary mercury concentrations using either 20 or 100 µg/g creatinine thresholds. Median urinary mercury levels were higher among workers with tremor than those without, although the difference was not statistically significant (13.78 vs. 10.75 µg/g creatinine; p = 0.678).

Conclusions. Tremor prevalence was 8.5% higher than the general population. Older age was the only factor significantly associated with tremor, whereas occupational mercury exposure indicators were not significantly associated in this study. Smoking habit, workers’ job type, exposure to elemental mercury vapor, and pesticide exposure had no significant association with tremor.