环境中哪一种污染物不易引起持续性蓄积危害

A:DDT B:氰化物 C:PCBs D:镉 E:铅

下列是环境中易引起持续性蓄积危害的污染物，哪项除外（）。

A:DDT B:氰化物 C:PCBs D:镉 E:铅

气相色谱法测定海水中PCBs时，富集样品中多氯联苯所用的国产1300（I）型树脂（相当于AmberliteDAX-2）属于（）吸附剂。

A:键合硅胶类 B:有机聚合物 C:碳基 D:正相固相

气相色谱法测定海水中PCBs时，采用（）方法提取样品中的PCBs。

A:液液萃取 B:固相萃取 C:索氏提取 D:连续液液萃取

气相色谱法测定海水中PCBs时，活性炭在使用前需经（）℃烘4h，装具塞玻璃瓶中，置于干燥器保存。

A:200 B:280 C:360

多氯联苯（PCBs）

持久的有毒物质包括农药、PCBs和其他有毒有机化合物、重金属、（）

（）是表示生化需氧量。

A:BOD B:PAH C:PCBs D:ABS

In 2005 scientists in Spain reported that the more pesticides children were exposed to as fetuses (胚胎), the greater their risk of being overweight as toddlers. And last January scientists in Belgium found that children exposed to higher levels of PCBs and DDE ( the breakdown product of the pesticide DDT) before birth were fatter than those exposed to lower levels. Neither study proves causation, but they "support the findings in experimental animals," says Newbold. They "show a link between exposure to environmental chemicals...and the development of obesity. "
In the paragraph the writer intends to convey to the reader that

A:there might be a link between exposure to environmental chemicals and the development of obesity. B:there is a cause - effect relation between exposure to environmental chemicals and obesity. C:children who are exposed to pesticides are likely to develop obesity in their adulthood. D:scientists have done experiments to see the link between environmental chemicals and obesity for years.