The use of DDT as an insecticide in the United States has been outlawed since 1971, yet is still a problem for certain top-level carnivores in the United States. Which of the following choices best explains this apparent incongruity?
A) DDT is still used for mosquito control in tropical countries, and certain migratory predators can be affected by a seasonal biomagnification.
B) DDT is persistent in the environment and all of the pre-1971 DDT is still available in toxic form to poison top-level carnivores.
C) Pre-1971 DDT has been deposited in certain habitats, particularly wetlands and estuaries, so predators in these ecosystems are vulnerable to biomagnifications of DDT.
D) Whereas most DDT-susceptible species have become resistant to persistent DDT, others are still vulnerable.
E) All of the options are correct.
Several species of squirrels have melanistic phases. In large parts of United States and Canada, the
Prevalence of Obesity in the United States
Change in Emotional States During Adolescence Average emotional state becomes teadilyi more negativ
The United States and Its Territories, 1787–1802
How Urban Is Your State? The Rural-Urban Makeup of the United States
Guide to Major Massage Therapy Organizations in the United States*