PCBs are extremely persistent in the environment because they are very stable, non-reactive, and highly heat resistant. PCB use and sale was banned in 1979 with the passage of the Toxic Substances Control Act. PCBs are known to bioaccumulate in fatty tissues and believed to cause liver damage from chronic exposure. Pesticide - Any chemical designed to kill or inhibit the growth of an organism that people consider undesirable. The chemicals are used as raw materials in the manufacture of most industrial chemicals, fertilizers, pesticides, plastics, synthetic fibers, paints, medicines, and many other products.
Examples are a smokestack, sewer, ditch, or pipe.
Pollution - A change in the physical, chemical, or biological characteristics of the air, water, or soil that can affect the health, survival, or activities of humans in an unwanted way. Some expand the term to include harmful effects on all forms of life. Population Density - The number of persons living in a one square mile area of land. The inability to meet basic needs. People in different societies differ in what they consider to be basic needs.