Medically reviewed by Timothy Rebbeck, PhD
Lawn care can help grass become and stay full, green, and healthy, but are the chemicals and fertilizers that you use to take care of your lawn increasing your cancer risk?
Fertilizers, herbicides, and pesticides are common lawn care products. Although frequent exposure to chemicals in these products can have negative effects on a person’s health, the average exposure isn’t enough to increase your cancer risk.
Fertilizers often contain nitrates that increase nutrients in plants, allowing them to properly develop foliage and produce flowers and seeds. While nitrates occur naturally, they can also be also added to fertilizer to boost plant growth. High amounts of nitrates are found in lettuce, beets, spinach, and other root vegetables.
Vegetables are one of the biggest sources of human exposure to nitrates. However, vegetables also contain compounds that prevent the formation of N-nitroso compounds (NOCs), which are known to cause cancer in animals and may cause cancer in humans. N-nitroso compounds are formed when nitrates react with other natural chemicals in the body.
Human exposure to these nitrates often comes through drinking water; however, this is more common in agricultural areas where nitrates are used in large amounts near water supplies. According to the National Cancer Institute, higher ingestion of water nitrate in agricultural areas (and therefore increased NOC formation) might increase risk of colon, kidney, and stomach cancer, compared to lower intakes. Another common side effect of human exposure to nitrates is the development of a blood disorder in infants called methemoglobinemia, but this is rare.
Often referred to as weed killers, herbicides are used to control unwanted weeds, grasses, and other vegetation. The most common chemicals in herbicides include glyphosate, N-(Phosphonomethyl)glycine (2,4-D), and methylchlorophenoxypropionic acid (MCPP).
Glyphosate is the most widely used herbicide in the United States. Found in popular weed killers, the chemical blocks enzymes that regulate plant growth. Its widespread use means that human exposure to glyphosate is common in water, food, and dust.
While recent news alleges a link between glyphosate and cancer from chronic use of the chemical, and in 2017, the World Health Organization’s International Agency for Research on Cancer determined that glyphosate is a “probable human carcinogenic”; the Environmental Protection Agency (EPA) continues to find that glyphosate is not a carcinogen when used as directed by the label.
2,4-D is used to control plant growth and most often applied to prevent the growth of weeds. Chronic exposure to 2,4-D can be possibly carcinogenic, but the evidence is limited. There is also insufficient evidence that MCPP increases cancer risk, as it has not been thoroughly evaluated for its human carcinogenic potential.
Pesticides are used to destroy weeds, control insects, prevent the growth of mold and bacteria, and deter mice and rats. Dicamba is one of the most widely used pesticides; it is also used to control unwanted plant growth. Brief exposure to dicamba, such as using it in your lawn or garden, may cause side effects such as dizziness. However, it is low in toxicity; there is no clear link between dicamba and an increased risk of cancer.
Some pesticides contain arsenic, a naturally occurring element and known carcinogen that is found in soils and minerals. Arsenic is commonly used as a weed killer; most forms of the chemical tend to stick to soil, but some can dissolve in water. Pesticides that contain arsenic have been linked to increased cancer risk in agricultural workers who are chronically exposed, but not to the average person. It is largely difficult to measure human exposure to arsenic, so despite these studies, the data are inconclusive.
Tips for protection
While there is no conclusive evidence that lawn care products and infrequent exposure cause cancer, here are some ways you can protect yourself while caring for your lawn or garden:
- Wear gloves and masks while using chemicals and pesticides.
- Follow directions on the packaging.
- Limit time spent in the yard immediately after applying lawn care treatments.
Tools such as rakes and garden hoes, and manual labor, can offer an alternative to chemicals when it comes to maintaining your lawn or garden.