Miss Carson and other scientists were very concerned about the harmful effects of DDT and other insect-killing chemicals called pesticides.

VOA: special.2010.03.14

Or it can the kind of change we talked about before, where during division there are some chemicals that are trapped in one cell and not in the other, and that could lead to a difference we already talked about.

可能是我们之前说过的,在分裂过程中可能发生的,不对称分裂的现象,并导致我们已经讲过的某些不同

耶鲁公开课 - 生物医学工程探索课程节选

It can also contain other pollutants like chemicals from agriculture and industry.

VOA: special.2010.07.19

In studying babies' brains, the researchers found that babies who died of SIDS had 25 percent less serotonin and related chemicals than the babies who died of other causes.

VOA: standard.2010.02.08