Pollution Run-Off 
Although the tumors on the turtle's flippers above are not said to be a direct result of malathion, there is very strong evidence that pesticide runoff may play a significant part in causing the cancers on the turtles.

Our Tampa Bay and river systems are currently stressed severely by the impact of pesticides and chemicals from lawn spray applications and conventional citrus grove run-off.  Fish and other aquatic organisms (especially shrimp) have been reported as experiencing mutations in development and alterations in important behaviors critical to the survival of the organism. 

50-65% of turtles throughout sections of Florida's rivers are being found with tumors over their bodies (note the whitish growths along the front of the turtle's flippers). Although the tumors are believed to result from viral infections, the fact that only turtles in polluted waters have the tumors raises questions to the potential for pesticides and chemicals to weaken the immune systems of the turtles. It is our immune system that must function properly to constantly remove cancer cells as they develop. When the immune system is weakened enough in any living mammal, cancer cells can then grow more rapidly. 

In an article on the increased number of tumors being found on turtles, appearing in the April 21, 1996 Vero Beach, Press Journal, Florida biologist Liew Ehrhart stated pollution is the"one common thread." Dr. Ehrhart went on to say, 

"It only crops up in populations in degraded water. In bays, sounds and lagoons that have runoff, either urban or agricultural. In pristine water, they don't have the disease."