Pastinaca sativa can overwhelm locations where native vegetation hasn't fully established. Wild parsnips are very persistent along edges and disturbed areas, and are found commonly in bare locations, like paths, roadsides, and utility right of ways, and are aggresively competitive where native plants aren't well established. Because of being so prominent in disturbed areas, they can easily be spread by animals, and by humans that are working, hiking, or harvesting, and are often accidentally spread through clothing and equipment. It can also have substantial effects on human health. Some are sensitive to the plant and can develop a burning, blistering, discolored rash if they come in contact with the leaves or the sap and are exposed to direct sunlight. Skin sensitivity can last for up to a year after initial contact. This occurs most frequently in June and July, when the plant is in bloom.