Carson stated that chemicals treatment of soils led to the destruction of beneficial biological species, and that such destruction resulted in imbalance to the ecosystem. Also, wildlife that ate chemically killed worms also dies. She noted the long-term persistence of chlorinated hydrocarbons in soil and the possible transfer of chemicals into plants grown in such soils. She stated that government officials had aerially sprayed areas without notifying the public, and that these officials underestimated the safety problems of chemicals . Carson highly praised the desirability and great potential of using biological controls in place of chemicals, as well as use of natural products and less toxic chemicals (e.g., pyrethrins). She pointed out that scientists' and government officials' concerns addressed only classical toxicity of pesticides and that no testing was done on effects to wildlife. Regarding residues in food, she stated that government protection through the Food and Drug Administration was minimal and that tolerances