Lawn Fertilizers
Most popular brands of lawn fertilizer contain more nitrogen than is needed to grow and support healthy, strong grass plants. They are also often contaminated with per- and polyfluoroalkyl substances ("PFAS" - the 'forever' chemicals), as well as plastic. These lawn products pose a threat to our environment and our health.
Excess Nitrogen
Most of the top selling brands of lawn fertilizers contain large amounts of water-soluble synthetic nitrogen (more than 12%). During irrigation or a rain event, only a small portion of the nitrogen settles in the root zone of grass plants where it is needed. Much of it either washes away with the rain into nearby surface waters or migrates down past the root zone and into underground aquifers where it can contaminate drinking water.
Nitrogen is a proven hazard in drinking water sources. Excess nitrogen can be harmful for infants, leading to "blue baby syndrome," where the blood's ability to carry oxygen is impaired. Long-term exposure to nitrogen in drinking water may also be associated with thyroid problems, adverse pregnancy outcomes, and certain cancers.
Fast Facts
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Most commercial lawn fertilizers contain high levels of synthetic nitrogen (above 12%) which contaminate our ground and surface waters.
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Some popular fertilizers also contain plastic coatings and PFAS "forever" chemicals that endanger health.
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Natural (organic) fertilizers work just as well and require smaller amounts to produce great results.
In surface waters, excess nitrogen can lead to algal blooms and fish kills. Contact with blue green algae can cause skin irritation and mild respiratory effects, and can be lethal to dogs. Emerging science is linking airborne toxins from blue-green algae with serious health conditions, including ALS. Ingesting algae toxins can cause gastroenteritis symptoms, such as vomiting, diarrhea, fever and headaches.
Synthetic nitrogen fertilizers also contribute significantly to greenhouse gas emissions. Especially while they are being applied, they release carbon dioxide (CO2), methane (CH4), and nitrous oxide (N2O). About 300 times more potent than carbon dioxide, but less abundant in the atmosphere, nitrous oxide released from fertilizer applications plays an important role in climate change.
Plastic
To address the rapid solubility problem, fertilizer companies encapsulate some of their synthetic nitrogen in a plastic coating so that it breaks down slowly with sunlight and rain. Eventually the plastic deteriorates, the nitrogen is released, and the plastic is left in environment, where it breaks down further into micro- and nanoplastics, endangering human health.
Recent studies have found microplastics in every human organ studied, with highest levels found in the brain. Exposure to microplastics has been linked to a range of adverse health effects, including oxidative stress, inflammation, neurological disorders and potential damage to the digestive, respiratory, and reproductive systems.
PFAS
Some lawn fertilizers contain PFAS-laden municipal sewage sludge (also known as "biosolids") as a primary source of inexpensive nitrogen. PFAS is also commonly used in the production of fertilizer to facilitate the manufacturing process.
PFAS chemicals are being linked to a growing list of human health conditions, including liver damage, thyroid disease, obesity, decreased fertility, and cancer. PFAS can be toxic in tiny amounts, and legal limits are being set at parts-per-trillion, although researchers have found harm at levels in parts-per-quadrillion.
Most natural (organic) fertilizers don't contain PFAS, plastic, or high levels of water-soluble nitrogen. Instead, their naturally occurring nitrogen is broken down over time by soil microbiology to make nutrients available to plants. There is no waste, and less of the product is needed to achieve the same result on your lawn. For more information, please​ see our page on natural lawn fertilizers that won't harm humans or the environment.
More Resources on Lawn Fertilizers
• Our Long Island Water program contains lots of information and scientific studies on nitrogen, plastic, and PFAS in lawn fertilizers and their impact on the environment.
• See the Digest of Studies and Reports on Impacts to Ground and Surface Waters from Turf Fertilizers
• See a list of retailers in Westchester County who carry natural lawn fertilizers.
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• See draft legislation for Westchester County regarding excess nitrogen, PFAS, and plastic in lawn fertilizers.