Milestones in Biology 6: Test Your Knowledge

On the origins of DDT:

a. When was the chemical DDT first widely used, and what was its intended purpose?

b. How effective was it for that purpose?

On the mechanism of DDT:

a. How does DDT kill insects?

b. How does DDT harm top predator birds?

What is biomagnification?

PCBs (polychlorinated biphenyls), a type of chlorinated hydrocarbon, were used for a variety of purposes (including electrical insulation), until their use was banned in 1979. A 2000 survey of top predator fish in the Great Lakes showed that the concentration of PCBs in these fish ranged from 0.8 to 1.6 ppm. The wildlife protection value (the concentration that should not be exceeded in order to protect the safety of wildlife) is 0.16 ppm. How could there be such high levels of PCBs in top predator fish 21 years after PCBs were banned?

In 2013, a group of beekeepers launched a lawsuit against the EPA concerning the use of neonicotinoid pesticides and possible unintended impacts on honey bees (see Chapter 22). From what you have read here, what kinds of testing would you want the EPA to require before approving a pesticide applied widely to crops such as corn or soybeans?