非必需微量元素

非必需微量元素如铅、镉、铝在各组中都明显超过正常值水平（P均<001）。

Pb , Cd , Al in hair were all higher than the normal level ( P < 0 01 ) .

目的研究必需和非必需微量元素在正常产妇毛发、静脉血及胎儿脐血间的分布规律，探讨胎盘屏障对母体和胎儿间微量元素转运的影响。

Objective To study the distribution of selected nutritional and toxic trace elements in mother 's hair , venous blood , and cord blood , and the blocking effects of the placental barrier to the transportation of trace elements from mother to her baby .

Cd是植物非必需的微量元素，对植物有很强的毒性。

Cadmium ( Cd ) is a non-essential trace element for plants , and has strong toxicity at low concentrations .

镉是一种生物体非必需的有害微量元素，也是水产品中重要的持久性污染物之一。

Not as an essential but as a harmful microelement to creatures , cadmium is one of the grave enduring pollutants in aquatic products .

目前大规模使用的生物医用材料镁合金有AZ31、WE43等。Al可能引起透析性脑病综合征、老年性痴呆等一些退行性神经疾病，被认为是一种非必需性的低毒微量元素。

At present , a large-scale used biomedical magnesium alloys mainly include AZ31 、 WE43 etc. However , the Al element may cause dialysis encephalopathy syndrome , alzheimer s disease and other degenerative neurological diseases , which is considered as a non-essential trace element of low toxicity .

研究人员说，这可能归因于存在于锌补充剂中的非必需的潜在有害微量元素，例如致癌物质镉。

This " could be due to nonessential , potentially harmful trace elements contained in zinc supplements , such as cadmium , a known carcinogen ," the researchers said .