There is concern over the use of 2,4-D, a synthetic plant hormone, as a weed killer because the by-product dioxin
◦ weakens the shells of the eggs of predatory birds, resulting in the death of their offspring.
◦ causes fruit to drop prematurely from plants.
◦ can cause irreversible mutations in crop plants.
◦ can cause birth defects and leukemia in mammals.