People who apply the pesticides suffer the greatest risk, which must be minimized by applicator training and use of protective clothing and equipment. Park visitors experience far less exposure than applicators. Environmental Risks . Herbicides have killed birds and fish, usually as a result of misapplications or accidental spills. Long-term exposure could have the same consequences for animals as for humans.
Some herbicides are very persistent and mobile and can contaminate ground and surface water.
This can impair ecosystem functions and threaten human health. The National Park Service uses Integrated Weed Management. Often, more than one method of weed control is used, and each method is carefully matched to the biology of the weed and the local environment. Spraying bittersweet with backpack equipment in Rock Creek Park, Maryland. Photograph by Rosa Wilson .