But the approach evolved in the 1950's to continue the microscopic analysis with less use of chemicals.
And we offer some alternatives for those who want to reduce their use of chemicals.
Obesity rates started rising just as the use of industrial chemicals took off 40 years ago.
These problems usually occur during the hot summer months, and are partially brought under control by the use of safe chemicals.
It also does not make use of toxic chemicals or catalysts.
The director will also personally approve the use of chemicals at the zoo, he said.
The use of chemicals in agriculture is not limited to pesticides.
It does not limit the use of the other 2 000 or so chemicals used in cigarettes.
These include, among other things, the use of chemicals in agriculture and forestry management.
The use of agricultural chemicals is not likely to end any time soon.