Abstract
BackgroundItai-itai disease primarily results from cadmium (Cd) exposure and is known as one of the four major pollution diseases in Japan. Cd pollution is more serious in several areas of China than in Japan. However, there is still a lack of information regarding the threshold level of Cd exposure for the adverse health effects in the general Chinese population. This study aims to evaluate the reference value of urinary Cd (UCd) for renal dysfunction in a Chinese population as the benchmark dose lower confidence limit (BMDL) based on a large sample survey.MethodsA total of 6103 participants who lived in five Cd polluted areas of China participated in this study. We analyzed UCd levels as a biomarker of exposure and urinary β2-microglobulin (Uβ2-MG) levels as a renal tubular effect biomarker. The BMD studies were performed using BMD software. The benchmark response (BMR) was defined as a 10 % additional risk above the background.ResultsThere was a positive correlation between the UCd levels and the prevalence of Uβ2-MG. The BMD of UCd for Uβ2-MG was estimated for each province. The findings showed that the BMD levels were related to the participants’ geographic region, which may be partially due to the large differences in Cd exposure level, ethnic group, lifestyle and diet of the sample population in these study areas. The reference level of UCd for the renal effects was further evaluated by combining the five sets of data from all 6103 subjects. The overall BMDLs of UCd for Uβ2-MG with an excess risk of 10 % were 2.00 μg/g creatinine (μg/g cr) in males and 1.69 μg/g cr in females, which were significantly lower than the World Health Organization (WHO) threshold level of 5 μg/g cr for Cd-related renal effects.ConclusionsThe selection of the sample population and geographic region affected the BMDL evaluation. Based on the findings of this survey of a large sample population, the UCd BMDLs for Uβ2-MG in males with BMRs at 10 % were 2.00 μg/g cr. The BMD was slightly lower in females, which indicated that females may be relatively more sensitive to Cd exposure than males.
Highlights
Itai-itai disease primarily results from cadmium (Cd) exposure and is known as one of the four major pollution diseases in Japan
The threshold value of 5 μg/g cr that was set by the World Health Organization (WHO) [29] was used as the cut-off value to calculate the prevalence of the elevated urinary Cd (UCd) levels
The benchmark dose (BMD) of UCd for renal dysfunction in the population of five different Chinese provinces was assessed individually using urinary β2-microglobulin (Uβ2-MG) as the effect indicator, and the results showed that the estimated BMD value was significantly affected by the participants’ geographic region and gender
Summary
Itai-itai disease primarily results from cadmium (Cd) exposure and is known as one of the four major pollution diseases in Japan. This study aims to evaluate the reference value of urinary Cd (UCd) for renal dysfunction in a Chinese population as the benchmark dose lower confidence limit (BMDL) based on a large sample survey. Cadmium (Cd) is a non-essential element in the human body, and long-term exposure to sufficiently high Cd levels through food and water consumption, skin contact and inhalation may cause adverse health effects, such as renal dysfunction and osteoporosis [1,2,3,4]. Compared with the NOAEL, the BMD method is not constrained as one of the experimental doses and makes better use of the dose–response information This method more appropriately reflects the sample size and is regarded as a better approach than NOAEL to estimate the reference point for a continuous outcome variable [12]
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