Toxic exposure and kidney function: Urinary creatinine and glomerular filtration rate in traditional sulfur miners

The Ijen Crater Volcano, recognized by UNESCO as a biosphere reserve, has a high sulfur content and is the main source of traditional sulfur mining work. However, exposure to natural sulfur in this area can cause health problems, especially in kidney function. This study aims to evaluate the relationship between exposure to toxic natural pollution and impaired kidney function. The study focuses on investigation of the toxic natural pollutants, namely SO₂ and heavy metals in the air. Urine samples were collected from 60 respondents who were divided into two groups: 30 sulfur miners as the exposure group (cases) and 30 local residents (control) who were not engaged in mining activities. Urine samples were collected for creatinine level analysis, and glomerular filtration rate (GFR) was calculated to assess kidney function. In the case group, 66% (20 out of 30) had urinary creatinine levels above the normal limit (≥1.3 mg/dL), while in the control group, only 30% (9 out of 30) exceeded this value. GFR analysis showed that only two respondents (6.7%) in the case group had normal kidney function (GFR ≥90 mL/min), while 53.3% (16 respondents) were in the moderate kidney function decline category (GFR 30-59 mL/min) and 13.3% (4 respondents) had severe kidney function decline (GFR 15-29 mL/min). In contrast, the control group had eight respondents (26.7%) with normal kidney function as well as a lower prevalence of moderate (23.3%) and severe (3.3%) kidney function decline. Exposure to toxic natural pollution in Ijen Crater Volcano was significantly associated with an increased risk of kidney function impairment, as indicated by higher urinary creatinine levels and lower GFR values in the case group. These results emphasize the importance of health surveillance and implementation of preventive measures for mine workers in this biosphere reserve area.