The greatest risk to our environment and our health comes from .....

The greatest risk to our environment and our health comes from the chemical pesticides. In spite of the dangers, the government maintains its approval of the use of toxic chemicals to make pesticides. And science is constantly developing variations of poisons.
Two classes are broad-spectrum and narrow-spectrum pesticides. Broad-spectrum pesticides kill many kinds of pests, while narrow-spectrum pesticides do just the opposite. Narrow-spectrum pesticides are developed to kill specific organism types. Examples are algicides for algai, avicides for birds, fungicides for fungi and oomycetes (also called water molds, they use surface water including preciptiation on plants, to move around). Most pesticides kill pests directly on contact. Systemic pesticides work differently. They penetrate to the inside of a plant traveling along its absorption path. These poisons work by poisoning the pollen and nectar of flowers and this can kill needed pollinators like butterflies and bees.