A 28‐year observational study of urinary cadmium and β₂‐microglobulin concentrations in inhabitants in cadmium‐polluted areas in Japan

Abstract

The biological half-life of cadmium (Cd) is as long as 10-30 years. Exposure to this element induces renal tubular dysfunction, which is considered irreversible. β -microglobulin (β -MG) is a low-molecular-weight protein, and urinary β -MG is one of the most useful and critical indicators for the early detection of renal tubular dysfunction. However, very little research has been published concerning the long-term observation of Cd-induced adverse health effects. As such, this follow-up study was conducted for 28 years to clarify the relationship between the concentration of Cd and β -MG in the urine of 28 inhabitants (14 male and 14 female) living in the Kakehashi River basin, Ishikawa prefecture (Japan), previously one of the most highly Cd-polluted regions in this country. All subjects were over 60 years old in 2014 and participated in all six health examinations conducted over 28 years (1986-2014). Urine was collected at the appropriate time and kept frozen to analyze urinary Cd and β -MG concentrations. The urinary Cd concentration was found to decrease by nearly half between 1986 and 2008 in both male and female subjects, whereas it increased significantly from 2008 to 2014 in males. In contrast, urinary β -MG concentrations tended to increase over the 28-year study period in both sexes. Urinary Cd and β -MG concentrations in females were significantly higher than those in males in this Cd-polluted region. Age is more strongly associated with urinary β -MG concentration than recent Cd body burden. Copyright © 2016 John Wiley & Sons, Ltd.

Hair Metal Levels and Childhood Weight Gain

“…In addition, some researchers have revealed higher blood levels of manganese, copper, arsenic, cadmium and selenium in females than males ( 38 – 40 ). Similar to hair and blood, higher levels of urinary cadmium in females than in males was shown ( 33 ). On the other hand, some studies on children have reported lower blood levels of lead in girls than in boys ( 32 , 34 ).…”

“…The current study results showed higher levels of some metals in girls’ than boys’ hair. Previous studies have reported accumulation of metals related to participants’ gender ( 33 – 36 ). For example, studies in Iran and Italy have reported higher level of scalp hair elements (i.e., lead, cobalt, cadmium, copper, and zinc) in girls than in boys ( 36 , 37 ).…”

An assessment of sensitivity biomarkers for urinary cadmium burden

“…Clinically ascertaining threshold concentrations of UCd is greatly important and aids understanding of the health risks. Sensitivity indexes for the UCd burden have been a topic of wide concerned [ 15 , 21 ]. In response to our questionnaire, more than 50% of respondents indicated their awareness of suffering high Cd exposure for a certain time.…”

“…Long-term Cd exposure has been reported, and renal dysfunction has already been proven [ 45 , 46 ]. Uβ 2 -MG and UNAG are in use as biomarkers for clinical diagnosis [ 15 , 21 ] and animal experiments [ 47 , 48 ]. In the later stages of Cd-induced renal injury, the tubular epithelial cells may shrink, fall off, and even disappear, and the tissue source of UNAG is lost [ 49 , 50 ].…”

“…A range of factors (including age, years of exposure, and gender) that affect the relationship between Cd burden and the prevalence of kidney dysfunction have been determined to contribute the Cd threshold [ 12 – 14 ], but the interaction mechanism remains unclear. A range of biomarkers of renal dysfunction have been used diagnostically in this context [ 15 , 16 ], including urinary N-acetyl-β-D-glucosidase (UNAG), urinary β 2 -microglobulin (Uβ 2 -MG), and urinary retinol binding protein (URBP) [ 17 – 19 ]. These three are likely valid biomarkers due to their origin in the renal tubules or in glomeruli breakage under urinary (UCd) pressure [ 20 – 22 ].…”