A 30 years follow-up study in the cadmium former polluted area in Japan: the relationship between cadmium exposure and β2-microglobulin in the urine of Japanese

Abstract Cadmium (Cd) is an environmental pollutant. Long-term exposure to Cd may lead adverse health effects in humans. Our epidemiological studies showed that urinary Cd (U-Cd) concentrations increased from 2008 to 2014, although they were reduced from 1986 until 2008. This aim of this study was to elucidate the long-term effects of the changing trend of cadmium exposure levels (U-Cd) on residents' renal function within 30 years after Cd-exposure ceased. In 2016, urine samples were collected from each participant by visiting 20 elderly Japanese (9 female and 11 male) living in the Kakehashi river basin; a previously Cd-polluted area in Ishikawa, Japan. The geometric means of the β2-microglobulin (β2-MG) and urinary Cd (U-Cd) continued increase to 2014 until 2016. Furthermore, Cd concentration and β2-MG in urine were still higher than those in the non-polluted areas in Japan. Significant correlations were found among age, U-Cd and β2-MG, and these were clearer in females than in males. In summary, we propose that three decades after Cd-exposure ceased, age has been more strongly associated with β2-MG than Cd body burden. Moreover, renal tubular dysfunction is irreversible and worsens after exposure to Cd, with females being more sensitive to exposure.