Application of benchmark dose (BMD) in estimating biological exposure limit (BEL) to cadmium.

OBJECTIVE: To estimate the biological exposure limit (BEL) using benchmark dose (BMD) based on two sets of data from occupational epidemiology. METHODS: Cadmium-exposed workers were selected from a cadmium smelting factory and a zinc product factory. Doctors, nurses or shop assistants living in the same area served as a control group. Urinary cadmium (UCd) was used as an exposure biomarker and urinary beta2-microgloburin (B2M), N-acetyl-13-D-glucosaminidase (NAG) and albumin (ALB) as effect biomarkers. All urine parameters were adjusted by urinary creatinine. Software of BMDS (Version 1.3.2, EPA.U.S.A) was used to calculate BMD. RESULTS: The cut-off point (abnormal values) was determined based on the upper limit of 95% of effect biomarkers in control group. There was a significant dose response relationship between the effect biomarkers (urinary B2M, NAG; and ALB) and exposure biomarker (UCd). BEL value was 5 microg/g creatinine for UB2M as an effect biomarker, consistent with the recommendation of WHO. BEL could be estimated by using the method of BMD. BEL value was 3 microg/g creatinine for UNAG as an effect biomarker. The more sensitive the used biomarker is, the more occupational population will be protected. CONCLUSION: BMD can be used in estimating the biological exposure limit (BEL). UNAG is a sensitive biomarker for estimating BEL after cadmium exposure.

[Application of Benchmark dose (BMD) in estimating biological exposure limit (BEL)].

OBJECTIVE: Based on two sets of data from occupational epidemiology, Benchmark dose (BMD) was applied to estimate biological exposure limit (BEL). METHODS: Cadmium exposed workers were selected from a cadmium smelting and a zinc products factory and control group was selected from doctors or nurses and staff from shops living in the same area; Urinary cadmium (UCd) was used as exposure biomarker and urinary beta(2) microglobulin (UBM), NAG (UNAG) and albumin (UALB) were as effect biomarkers. All urine parameters were adjusted by urinary creatinine. Software of BMDS (Version 1.3.2, EPA.U.S) was used to calculate BMD. RESULTS: Calculated abnormal prevalence was based on the upper limit of 95% of effect biomarkers in control group; There are significant dose response relationship between the prevalence of effect biomarkers (UBM, UNAG and UALB) and exposure biomarker (UCd); BEL was 5 microg/g creatinine for UBM as effect biomarker, It consists with the recommendation of WHO; BEL was 3 microg/g creatinine for UNAG as effect biomarker; BEL can be estimated by using the method of BMD; the more sensitive biomarker would used, the more occupational people would protected. CONCLUSION: The application of BMD in estimating biological exposure limit (BEL) is proper. UNAG is suggested as most sensitive biomarker to be used to estimate BEL for cadmium exposure.

[Application of benchmark dose (BMD) in a bone-effect study on a general population environmentally exposed to cadmium].

OBJECTIVE: To estimate the benchmark dose for osteoporosis caused by cadmium exposure in a Chinese general population with an epidemiological study. METHODS: The inhabitants living in both cadmium polluted and non-polluted areas served as the exposure group and the control group. Urinary cadmium (UCd) and Blood cadmium (BCd) were used as exposure biomarkers while the Z score was used as effect biomarker for the osteoporosis. RESULTS: The UCd and BCd in the habitants of the polluted areas were significantly higher than those in the habitants of the control area on average (P < 0.05) and the UCd and BCd in the habitants of the highly polluted areas were significantly higher than those in the habitants of the moderately polluted area on average (P < 0.05). The bone mineral density was significantly decreased in the groups of the highest UCd and BCd level compared with the 5 microg/g Cr group with the significant difference (P < 0.05). The morbidity of the osteoporosis would increase significantly with the increase of the cadmium exposure (P < 0.05) with the linear correlation (P < 0.05). BMDs were calculated using BMDS Version l.3.2 software and BMDLs were also determined. The BMDL of UCd for cadmium-induced osteoporosis was higher than those representing cadmium-induced renal dysfunction. CONCLUSION: High level of cadmium exposure can induce osteoporosis, which occurs later than renal damage related to cadmium exposure. The BMD is a practical method.