To subscribe, E-mail the words . . The environmental movement is taking a historic step forward as we speak. Other examples of persistent chemicals would include DDT, which has a half-life of roughly 20 years in the environment. There are thousands of persistent toxic chemicals and they are dangerous because they remain available for such a long time to poison plants, animals and humans. See Figure 1, which shows how the concentration of DDT is magnified 10 million times between water and birds in Long Island Sound.
Dots represent DDT and arrows show small losses through respiration and excretion.
The adverse consequences of bioaccumulative toxins may become understood only after it is too late. It is important to note that many of the most toxic, persistent, and bioaccumulative chemicals are formed by the use of the element chlorine. DDT, PCBs, dioxins, CFCs, and many pesticides are chlorine compounds. Most people know of chlorine because it disinfects their drinking water, kills germs in the local swimming pool, or bleaches their clothes in the washing machine. Unfortunately, when it is used by industry, chlorine produces a broad spectrum of toxins that persist in the environment and bioaccumulate.