1. DDT and the Environment Adapted from information at http://www.chem.duke.edu/~jds/cruise_chem/pest/ddtup. html http://www.chem.duke.edu/~jds/cruise_chem/pest/ddtup. html

2. DDT is an extremely persistent chemical. It gets into the fats of organisms, and it stays there. But what makes it so dangerous to organisms?

3. All cells, including nerve cells, have a plasma membrane, which is the cell's outer boundary. Like an egg shell, the plasma membrane separates the inside of the cell from the outside. The plasma membrane allows special substances to enter and leave the cell, (food, oxygen, water, etc.).

4. The plasma membrane is made up mostly of lipids (fats). DDT is fat soluble, and so it will dissolve easily into the plasma membrane. In order to get into the plasma membrane, the DDT must open up the membrane slightly to make room for itself. DDT, unfortunately, opens up the membrane a little too much and causes the cell to leak.

5. For a nerve cell, the concentration of Na+ and K+ inside and outside of a cell are especially important, because they help determine when the nerve cell will fire its signals. After DDT gets into the plasma membrane, nerve impulses (signals) no longer fire when they are supposed to.

6. Even small amounts of DDT can affect small microorganisms. This is especially true for microorganisms that live in the water (i.e. algae, and plankton), because the aquatic environment can bring more DDT in contact with these organisms. As an example of this high sensitivity, water that contains only 0.1 (g (micrograms) of DDT per liter can slow down growth and photosynthesis in green algae.

7. To get an idea of how dilute this water is, think about a paper clip, which weighs about one gram. Take that mass, and divide it by TEN million! Let's say that this tiny amount of DDT was dissolved in a quarter gallon of water. Remarkably, microorganism growth will be affected because of this!

8. Birds DDT is most famous for its effect on birds. Some research have shown that for certain species, DDT causes the thinning of eggshells.

9. Biological Magnification Biomagnification is an increase in concentration of a substance up the food chain.

10. One scientific study showed that in a species of predatory fish, the mass of mercury is 11 mg. The average mass of the fish is 2 000 g. What is the concentration of mercury in the fish in parts per million?

11. A scientific study reported that seabirds living in a particular lagoon contained 25 ppm of DDT, although DDT-sprayed water contained only 3 ppm of the insecticide. What mass of DDT would be present in a 4.0 kg seabird containing this concentration of DDT?