A follow-up study on renal tubular dysfunction in inhabitants of a cadmium-polluted area : Considerations for risk assessment for environmental exposure to cadmium

1)对富山金足河流域居民近端肾小管功能障碍(PRTD)的进展情况进行了17年的随访研究。尿中β_2-微球蛋白(β_2-MG)和α_1-MG排泄量的显著增加表明，尽管过去17年来镉暴露减少，但早衰是不可逆的和进行性的。2)在镉污染的金祖江流域，未对镉致早衰的中年妇女进行充分的骨代谢检查。对自1934年起出生的8例β_2-MGURA超过1 mg/g Cr的妇女进行了临床和生化检查。3)对12例β_2-MGuria患者(6名女性和6名男性)的20年临床回顾显示，在女性中，最初研究中β_2-MGuria<1 mg/g Cr的患者没有发生PRTD，但β_2-MGuria>30 mg/g Cr的患者20年后发展为慢性肾功能衰竭。1例诊断为骨软化症，表现为低磷血症，血清碱性磷酸酶活性升高，右侧股骨假性骨折。在男性中，最初研究中β_2-MGURIA低于3毫克/克铬的受试者因患有膀胱癌或输尿管结石而患上生殖器功能障碍。4)1946年至1955年出生的居民中，尿镉排泄水平(Cd在肾脏中积累的指标)随着在镉污染的金祖河流域居住时间(年数)的增加而显著增加。男性和女性均未发现β_2-Muria病例，与β_2-Muria在老年人群中的高患病率形成鲜明对比。

1)A seventeen-year follow-up study was carried out to elucidate the progress of proximal renal tubular dysfunction (PRTD) in inhabitants of the cadmium (Cd)-polluted Jinzu River basin in Toyama. Significantly increased levels of urinary excretion of β_2-microglobulin (β_2-MG) and α_1-MG indicate that PRTD was irreversible and progressive, despite the fact that Cd exposure had decreased over the past 17 years.2)Bone metabolism in Cd-induced PRTD has not been fully examined in middle-aged women of the Cd-polluted Jinzu River basin. Clinical and biochemical examination was carried out in 8 women with β_2-MGuria exceeding 1 mg/g Cr and were born from 1934 on. Of the 8 women, three subjects were diagnosed as PRTD, and two of them had vertebral fractures, and moreover, one of these two subjects suffered a fracture of the right femoral neck.3)A twenty-year clinical review of 12 patients (6 women and 6 men) with β_2-MGuria showed that, in women, subjects having β_2-MGuria less than 1 mg/g Cr in the initial study did not develop PRTD but subjects having β_2-MGuria more than 30 mg/g Cr developed chronic renal failure after 20 years. One patient was diagnosed as osteomalacia showing hypophosphatemia, increased serum alkaline phosphatase activity and pseudo fracture of right femur. In men, subjects having β_2-MGuria less than 3 mg/g Cr in the initial study developed PRTD because of having bladder cancer or ureteral stone as a complication.4)Urinary Cd excretion level, an indicator of Cd accumulation in the kidney, significantly increased with increased duration (years) of residence in the Cd-polluted Jinzu River basin in inhabitants born between 1946 and 1955. There was no case of β_2-MGuria in both men and women, in contrast to the high prevalence of β_2-MGuria observed in older generations.