Herbicides are incredibly useful chemicals. Farmers, ranchers, gardeners and landscapers can use herbicides to selectively eliminate undesirable plants, saving themselves from the laborious and time-consuming chore of weeding. Yet the use of herbicides comes at a price. Herbicides are toxic and have a variety of unwanted effects on the people who use them and the environment around them.
Many herbicides and other pesticides are carcinogenic. According to Environmental Health Perspectives, the International Agency for Research on Cancer classified 26 pesticides as "having sufficient evidence of carcinogenicity in animals" and another 19 as "having limited evidence in animals" as of 1997. This includes six herbicides registered in the United States. Children are particularly likely to be exposed to herbicides, since they spend more time on the ground and playing in the dirt. According to the Tails a Waggin' website, dogs are also at increased risk, with the dogs of owners who spray the herbicide 2,4-Dichlorophenoxyacetic acid twice as likely to get cancer. A study published in 1990 in the journal "Epidemiology" by Shelia Hoar Zahm and others also found significantly higher cancer rates for farmers who use 2,4-Dichlorophenoxyacetic acid.
Many farmers and gardeners spray their crops with a single herbicide year after year. Over time, pests can develop an immunity to the herbicide. Either the herbicide will cease to work on a particular pest or higher and higher amounts will be required to get the same effect. According to the World Bank, the risk of herbicide resistance can be decreased by using a combination of different herbicides rather than a single one.
Harm to Wildlife
The use of herbicides can harm wildlife as well as humans and domestic animals. Some herbicides are moderately toxic to fish and other animals and can harm them directly. More significantly, however, herbicides harm animals by altering their environment. Goatweed, pigweed and many other plants usually seen as weeds are essential to wildlife. Eliminating them completely with herbicide use can harm birds and other animals that rely on them for food.