Yang G, Yin S, Zhou R, Gu L, Yan B, Liu Y, Liu Y
Department of Communal Nutrition, Chinese Academy of Preventive Medicine, Beijing.
J Trace Elem Electrolytes Health Dis. 1989 Sep;3(3):123-30.
Selenosis occurs in areas of Enshi county because of the high Se content of the food. Morphological changes in finger-nails were used as the main criterion for clinical diagnosis of selenosis. Pathological nails were observed to occur almost only in adults, not at all in young children and very seldom in teenagers. Symptoms of selenosis in susceptible patients were found at or above an Se-intake of 910 micrograms/d, corresponding to a blood Se level of 1.05 mg/L. There was no evidence for an increased susceptibility to dental caries due to high Se consumption, and an increase in Se-intake seems unlikely to reduce the beneficial effects of fluoride on caries. No abnormalities of liver or heart were seen by supersonic B or electrocardiographic examinations. The biochemical investigations showed that with increasing whole blood Se the ratio of plasma Se to erythrocyte Se tended to decrease. As Se-intake increases to over 750 micrograms daily, the ratio decreases to near a minimal level. Reduced glutathione in whole blood decreases within a blood Se range of 1.01 to 2.28 micrograms in the high Se area. The amount of trimethylselenonium ion excreted in urine increased with the increase of urinary Se. Cases with prolonged prothrombin time occurred as blood Se increased to a level above 1 mg/L. The white blood cell count also increased significantly. Quantitative values were obtained only for ratio of plasma-Se to erythrocyte-Se for prothrombin time and for maintenance of nail Symptoms of susceptible patients. The overall results indicated that a daily Se-intake of 750-850 micrograms [corrected] might be the marginal level of safe intake. When other variable factors are also taken into consideration a daily Se-intake of 400 micrograms [corrected] is suggested as the maximum daily safe intake. At this level of Se-intake the corresponding approximate tissue Se levels are: whole blood 0.559 mg/L, plasma 0.327 mg/L, urine excretion 173 micrograms/d, hair 3.60 mg/kg, toe-nails 4.25 mg/kg, and finger-nails 4.70 mg/kg.
由于食物中硒含量高，恩施县部分地区出现了硒中毒现象。指甲的形态变化被用作硒中毒临床诊断的主要标准。病理性指甲几乎只出现在成年人中，幼儿中完全没有，青少年中也很少见。易感患者出现硒中毒症状时，硒摄入量达到或超过910微克/天，相应的血硒水平为1.05毫克/升。没有证据表明高硒摄入会增加患龋齿的易感性，而且增加硒摄入量似乎不太可能降低氟化物对龋齿的有益作用。超声B检查或心电图检查未发现肝脏或心脏有异常。生化研究表明，随着全血硒含量的增加，血浆硒与红细胞硒的比值趋于下降。当硒摄入量增加到每天超过750微克时，该比值降至接近最低水平。在高硒地区，全血中还原型谷胱甘肽在血硒范围为1.01至2.28微克时会减少。尿中排出的三甲基硒离子量随尿硒的增加而增加。当血硒增加到1毫克/升以上时，会出现凝血酶原时间延长的病例。白细胞计数也显著增加。仅获得了血浆硒与红细胞硒比值、凝血酶原时间以及易感患者指甲症状维持情况的定量值。总体结果表明，每天摄入750 - 850微克[校正后]的硒可能是安全摄入的临界水平。当考虑其他可变因素时，建议每天摄入400微克[校正后]作为每日最大安全摄入量。在这个硒摄入水平下，相应的近似组织硒水平为：全血0.559毫克/升，血浆0.327毫克/升，尿排泄173微克/天，头发3.60毫克/千克，趾甲4.25毫克/千克，指甲4.70毫克/千克。
